CN218262075U

CN218262075U - Dialysis membrane stack, electrodialysis equipment or bipolar membrane equipment and water treatment system thereof

Info

Publication number: CN218262075U
Application number: CN202220452996.XU
Authority: CN
Inventors: 李玉宽
Original assignee: Best Tech Water Treatment Environmental Technology Dalian Co ltd
Current assignee: Best Tech Water Treatment Environmental Technology Dalian Co ltd
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2023-01-10
Anticipated expiration: 2032-03-03

Abstract

The utility model provides a dialysis membrane stack, electrodialysis equipment or bipolar membrane equipment and a water treatment system thereof, wherein the membrane stack is arranged between an electrode positive plate and an electrode negative plate, and comprises a bipolar membrane and a nanofiltration membrane; or the membrane stack comprises a bipolar membrane sheet, a nanofiltration membrane sheet, and a positive membrane sheet and/or a negative membrane sheet; or the membrane stack comprises nanofiltration membrane sheets, and positive membrane sheets and/or negative membrane sheets. The novel membrane stack increases different kinds of functions of the membrane stack, and achieves special effects for the water quality of a specific treatment target aqueous solution and specific treatment purpose requirements.

Description

Dialysis membrane stack, electrodialysis equipment or bipolar membrane equipment and water treatment system thereof

Technical Field

The utility model belongs to the water treatment field, concretely relates to dialysis membrane stack, electrodialysis equipment or bipolar membrane equipment and water treatment system thereof.

Background

The effect produced by a conventional electrodialysis device was concentration, with which the concentration was performed, with the following results for treating the following influent water quality:

however, given the special needs of the people, for example, the treated water contains univalent cations, univalent anions and divalent cations, the people can not obtain 2 products (the concentration chamber is a salt formed by univalent cations and univalent anions, and the concentration chamber is mainly a salt formed by univalent anions and divalent cations) by using electrodialysis equipment.

One of the conventional bipolar membranes (a three-compartment bipolar membrane) gave the following results for treating the following influent water quality:

however, given the special requirements, such as the water to be treated containing monovalent cation, monovalent anion and divalent cation, we can't obtain 3 products (alkali corresponding to monovalent cation in the first alkali chamber, alkali corresponding to divalent cation in the second alkali chamber, and acid corresponding to monovalent anion in the acid chamber) with bipolar membrane equipment.

Another of the conventional bipolar membranes (two-compartment bipolar membrane) when the bipolar membrane and the anode membrane combination were selected, the following inlet water quality results were obtained for the treatment:

however, given the special requirements, such as the water to be treated containing monovalent cation, monovalent anion and divalent cation, we can't obtain 2 products (the alkali corresponding to monovalent cation in the first alkali chamber and the alkali corresponding to divalent cation in the second alkali chamber) by using bipolar membrane equipment.

Another of the conventional bipolar membranes (two-compartment bipolar membrane) when the bipolar membrane and the negative membrane combination are selected, the following inlet water quality results are obtained for the treatment:

however, given the special requirements of the bipolar membrane device, such as the water to be treated containing monovalent cations, monovalent anions and divalent anions, the bipolar membrane device is not capable of obtaining 2 products (acid chamber one is acid corresponding to monovalent anions, and acid chamber two is mainly acid corresponding to divalent anions).

SUMMERY OF THE UTILITY MODEL

The ions in water can be classified into four types according to their positive and negative valence states: <xnotran> ( , , , , ), ( , , , , , , , , ), ≥ ( , , , , , , , , , , , , , ), ≥ ( , , , , , , ), "≥ " , ＞ ; </xnotran> Similarly, all "divalent anions" include divalent anions as well as trivalent, tetravalent, etc. > divalent anions, and valency refers to valence.

For solving prior art's problem, the utility model provides a dialysis membrane stack, electrodialysis equipment or bipolar membrane equipment and water treatment system thereof, this membrane stack has increased the different kind's of membrane stack function, to the quality of water and the specific treatment purpose needs of specific treatment target aqueous solution, reaches special effect through this neotype membrane stack, electrodialysis equipment or bipolar membrane equipment and water treatment system thereof.

A dialysis membrane stack, the membrane stack being disposed between a positive electrode plate and a negative electrode plate:

the membrane stack comprises a bipolar membrane and a nanofiltration membrane;

or the membrane stack comprises a bipolar membrane sheet, a nanofiltration membrane sheet, and a positive membrane sheet and/or a negative membrane sheet;

or the membrane stack comprises nanofiltration membrane sheets, and positive membrane sheets and/or negative membrane sheets.

Based on the above membrane stack, it is preferable that the order of arrangement of the membrane sheets from the electrode positive plate to the electrode negative plate is:

membrane stack I-1: the membrane stack I-1 at least comprises a group of combinations formed by the bipolar membrane, the negative membrane and the nanofiltration membrane;

or a membrane stack I-2: the membrane stack I-2 at least comprises a group of combinations formed by the bipolar membrane, the nanofiltration membrane and the anode membrane;

or a membrane stack I-3: the membrane stack I-3 at least comprises a group of combinations formed by the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane;

Or a membrane stack I-4: the membrane stack I-4 at least comprises a group of combinations formed by the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane;

or a membrane stack I-5: the membrane stack I-5 at least comprises a group of combinations formed by the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane;

or a membrane stack I-6: the membrane stack I-6 at least comprises a group of combinations formed by the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane;

or a membrane stack II-1: the membrane stack II-1 at least comprises a group of combinations formed by the bipolar membranes and the nanofiltration membranes;

or a membrane stack II-2: the nanofiltration membrane and the bipolar membrane are combined, and the membrane stack II-2 at least comprises a group of combinations formed by the nanofiltration membrane and the bipolar membrane;

Or a membrane stack II-3: the membrane stack II-3 at least comprises a group of combinations formed by the bipolar membrane, the anode membrane and the nanofiltration membrane;

or a membrane stack II-4: the membrane stack II-4 at least comprises a group of combinations formed by the negative membrane, the bipolar membrane and the nanofiltration membrane;

or a membrane stack III-1: the nanofiltration membrane and the positive membrane are combined, and the membrane stack III-1 at least comprises a group of combinations formed by the nanofiltration membrane and the positive membrane;

or a membrane stack III-2: the membrane stack III-2 at least comprises a group of combinations formed by the negative membrane and the nanofiltration membrane;

or a membrane stack III-3: the membrane stack III-3 at least comprises a group of combinations formed by the negative membrane, the positive membrane and the nanofiltration membrane;

or a membrane stack III-4: the membrane stack III-4 at least comprises a group of combinations formed by the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane.

Based on the above film stack, it is preferable that the order of arranging the film sheets in the direction from the electrode positive plate → the electrode negative plate is:

membrane stack I-1: the bipolar membrane, the cathode membrane and the nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are in the forms of a bipolar membrane, a negative membrane, a nanofiltration membrane, a bipolar membrane, a negative membrane and a nanofiltration membrane in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack I-2: the electrode comprises a bipolar membrane, a nanofiltration membrane and an anode membrane which are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are combined, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the bipolar membrane, the nanofiltration membrane, the anode membrane, the bipolar membrane, the nanofiltration membrane and the anode membrane are formed in a sheet form in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

Or a membrane stack I-3: the electrode negative plate is characterized in that a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are sequentially in the form of a bipolar membrane, a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack I-4: the electrode comprises a bipolar membrane, a nanofiltration membrane, a negative membrane and a positive membrane which are sequentially combined, wherein when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are sequentially in the form of a bipolar membrane, a nanofiltration membrane, a negative membrane, a positive membrane, a bipolar membrane, a nanofiltration membrane, a negative membrane and a positive membrane; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

Or a membrane stack I-5: the electrode comprises a bipolar membrane, a negative membrane, a positive membrane and a nanofiltration membrane which are sequentially used as a combination, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are in the forms of a bipolar membrane, a negative membrane, a positive membrane, a nanofiltration membrane, a bipolar membrane, a negative membrane, a positive membrane and a nanofiltration membrane in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack I-6: the electrode comprises a bipolar membrane, a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane which are sequentially combined, wherein when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are sequentially in the form of a bipolar membrane, a first nanofiltration membrane, a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

Or a membrane stack II-1: the bipolar membrane and the nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are sequentially in the forms of a bipolar membrane, a nanofiltration membrane, a bipolar membrane and a nanofiltration membrane; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack II-2: the nanofiltration membrane and the bipolar membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and arranged between the former combination and the electrode negative plate, and the method specifically comprises the following steps: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the combination is in the form of a nanofiltration membrane, a bipolar membrane, a nanofiltration membrane and a bipolar membrane in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

Or a membrane stack II-3: the electrode comprises a bipolar membrane, an anode membrane and a nanofiltration membrane which are sequentially used as a combination, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the two combinations are in the forms of a bipolar membrane, an anode membrane, a nanofiltration membrane, a bipolar membrane, an anode membrane and a nanofiltration membrane in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack II-4: the negative membrane, the bipolar membrane and the nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the negative membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane are formed in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

Or a membrane stack III-1: the nanofiltration membrane and the anode membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and arranged between the former combination and the electrode negative plate, and the method specifically comprises the following steps: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the combination is in a nanofiltration membrane, an anode membrane, a nanofiltration membrane and an anode membrane sheet form in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack III-2: the negative membrane and the nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the combination is in the form of a negative membrane, a nanofiltration membrane, a negative membrane and a nanofiltration membrane in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

Or a membrane stack III-3: the negative membrane, the positive membrane and the nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are set, the latter combination is close to the former combination and arranged between the former combination and the electrode negative plate, and the method specifically comprises the following steps: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the combination is in the form of a negative membrane, a positive membrane, a nanofiltration membrane, a negative membrane, a positive membrane and a nanofiltration membrane in sequence; when the number of the combinations is more than two, the latter combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like;

or a membrane stack III-4: the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane are sequentially used as a combination, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the specific steps are as follows: when two combinations are adopted, the second combination is arranged between the first combination and the electrode negative plate close to the first combination, and the combination is in the form of a negative membrane, a positive membrane, a first nanofiltration membrane, a second nanofiltration membrane, a negative membrane, a positive membrane, a first nanofiltration membrane and a second nanofiltration membrane in sequence; when the number of the combinations is more than two, the subsequent combinations are arranged between the former combination and the electrode negative plate close to the former combination, and the like.

Based on the membrane stack, the membrane stack I-1 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations and univalent anions, the alternating combination of a bipolar membrane, a negative membrane, a nanofiltration membrane, a bipolar membrane, a negative membrane and a nanofiltration membrane (a combination unit of the bipolar membrane, the negative membrane and the nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to a diagram I-1):

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the nanofiltration membrane (because the monovalent cations can not be intercepted by the nanofiltration membrane) and enter the alkali chamber, and are blocked by the bipolar membrane when moving towards the direction of the electrode negative plate, so that the monovalent cations are left in the alkali chamber;

the divalent cations in the water inlet chamber move towards the electrode negative plate and cannot pass through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent cations) and cannot enter the alkali chamber, and the divalent cations are left in the water inlet chamber;

Monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the acid chamber, and monovalent anions in the acid chamber move towards the direction of the electrode positive plate and are blocked by the bipolar membrane, so that the monovalent anions are remained in the acid chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxide radical moves to the positive electrode plate direction and enters the alkali chamber to form corresponding alkali with the univalent cation in the alkali chamber (the hydroxide radical can permeate the nanofiltration membrane again, but for the electroneutrality of the univalent cation in the alkali chamber, the hydroxide radical can be paired with the univalent cation in the alkali chamber in equal mol equivalent to generate the alkali);

the hydrogen ions move towards the negative electrode plate of the electrode and enter the acid chamber to form corresponding acid with univalent anions in the acid chamber.

And finally, the alkali corresponding to the monovalent cation is obtained in the alkali chamber, the acid corresponding to the monovalent anion is obtained in the acid chamber, namely, the alkali chamber product obtained from the aqueous solution containing the monovalent cation, the divalent cation and the monovalent anion only contains the alkali corresponding to the monovalent cation through the treatment of the membrane stack I-1.

(2) When the aqueous solution to be treated contains monovalent cation, divalent cation, monovalent anion and divalent anion, the alternating combination (the combination unit of bipolar membrane, negative membrane and nanofiltration membrane can be repeated for many times) comprising bipolar membrane, negative membrane, nanofiltration membrane, bipolar membrane, negative membrane and nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to the drawing I-1-1):

monovalent anions and anions not less than divalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the acid chamber, and the monovalent anions and anions not less than divalent anions in the acid chamber move towards the direction of the electrode positive plate and are blocked by the bipolar membrane, so that the monovalent anions and anions not less than divalent anions are remained in the acid chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

The hydrogen ions move towards the direction of the negative electrode plate of the electrode and enter the acid chamber to form corresponding acid with univalent anions and anions not less than divalent anions in the acid chamber.

And finally, the alkali corresponding to the monovalent cation is obtained in the alkali chamber, the acid corresponding to the monovalent anion and the divalent anion is obtained in the acid chamber, namely, the alkali chamber product obtained from the aqueous solution containing the monovalent cation, the divalent cation, the monovalent anion and the divalent anion only contains the alkali corresponding to the monovalent cation through the treatment of the membrane stack I-1.

(3) When the aqueous solution to be treated contains univalent cations, divalent anions and univalent anions, the alternating combination of a bipolar membrane, a negative membrane, a nanofiltration membrane, a bipolar membrane, a negative membrane and a nanofiltration membrane (a combination unit of the bipolar membrane, the negative membrane and the nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate of the electrode, an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane: the effect achieved at the moment is the same as that of the conventional three-compartment bipolar membrane, the alkali chamber generates alkali corresponding to univalent cations, the acid chamber generates univalent anions and acid corresponding to anions which are not less than divalent anions, and even if the cost of the nanofiltration membrane is much lower than that of the anode membrane, the cost is reduced and the method is beneficial to replace the anode membrane with the nanofiltration membrane of the three-compartment bipolar membrane.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination (the combination unit of the bipolar membrane, the negative membrane and the nanofiltration membrane can be repeated for many times) of the bipolar membrane, the negative membrane, the nanofiltration membrane, the bipolar membrane, the negative membrane and the nanofiltration membrane is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, an acid chamber is formed between the bipolar membrane and the negative membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane: the effect achieved at this time is the same as that of the conventional three-compartment bipolar membrane, the base chamber generates base corresponding to monovalent cation, and the acid chamber generates acid corresponding to monovalent anion, even if so, the cost of the nanofiltration membrane is much lower than that of the anode membrane, so that the cost is reduced and the method is beneficial to replace the anode membrane with the nanofiltration membrane of the three-compartment bipolar membrane.

Based on the membrane stack, the membrane stack I-2 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent anions and univalent anions, the alternating combination of a bipolar membrane, a nanofiltration membrane, an anode membrane, a bipolar membrane, a nanofiltration membrane and an anode membrane (a combination unit of the bipolar membrane, the nanofiltration membrane and the anode membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, an acid chamber is formed between the bipolar membrane and the nanofiltration membrane, a water inlet chamber is formed between the nanofiltration membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane (the specific connection mode and the principle refer to a diagram I-2):

Monovalent cations in the water inlet chamber move towards the electrode negative plate and pass through the anode diaphragm to enter the alkali chamber, and the monovalent cations in the alkali chamber are blocked by the bipolar diaphragm when moving towards the electrode negative plate, so that the monovalent cations are left in the alkali chamber;

monovalent anions in the water inlet chamber move towards the direction of the positive electrode plate of the electrode and pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) to enter the acid chamber, and the monovalent anions in the acid chamber move towards the direction of the positive electrode plate of the electrode and are blocked by the bipolar membrane, so that the monovalent anions are remained in the acid chamber;

divalent anions or more in the water inlet chamber move towards the direction of the positive electrode plate of the electrode and cannot penetrate through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) and cannot enter the acid chamber, so that the divalent anions or more are remained in the water inlet chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode and enters the alkali chamber, and corresponding alkali is formed by univalent cations in the alkali chamber;

the hydrogen ions move towards the electrode negative plate and enter the acid chamber to form corresponding acid with the monovalent anions in the acid chamber (although the hydrogen ions can permeate the nanofiltration membrane again, the hydrogen ions and the monovalent anions in the acid chamber are equivalent-matched with each other in an equimolar way to generate acid in the acid chamber for the purpose of electric neutrality of the monovalent anions in the acid chamber).

And finally, the base corresponding to the monovalent cation is obtained in the base chamber, the acid corresponding to the monovalent anion is obtained in the acid chamber, namely, the acid chamber product obtained from the aqueous solution containing the monovalent cation, the divalent anion and the monovalent anion only contains the acid corresponding to the monovalent anion through the treatment of the membrane stack I-2.

(2) When the aqueous solution to be treated contains monovalent cation, divalent cation, monovalent anion and divalent anion, the alternating combination (the combination unit of bipolar membrane, nanofiltration membrane and anode membrane can be repeated for many times) comprising bipolar membrane, nanofiltration membrane, anode membrane, bipolar membrane, nanofiltration membrane and anode membrane is arranged in the membrane stack from the direction of the electrode positive plate to the direction of the electrode negative plate, an acid chamber is formed between the bipolar membrane and the nanofiltration membrane, a water inlet chamber is formed between the nanofiltration membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane (the specific connection mode and the principle refer to the drawing I-2-1):

monovalent cations and divalent cations in the water inlet chamber move towards the electrode negative plate direction and penetrate through the anode diaphragm to enter the alkali chamber, and the monovalent cations and the divalent cations in the alkali chamber are blocked by the bipolar diaphragm when moving towards the electrode negative plate, so that the monovalent cations and the divalent cations are left in the alkali chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode and enters an alkali chamber, and corresponding alkali is formed by univalent cations and divalent cations which are not less than the univalent cations in the alkali chamber;

And finally, the alkali chamber obtains alkali containing univalent cations and corresponding to the bivalent cations, the acid chamber obtains acid corresponding to the univalent anions, namely, the acid chamber product obtained from the aqueous solution containing the univalent cations, the bivalent cations, the univalent anions and the bivalent anions only contains the acid corresponding to the univalent anions through the treatment of the membrane stack I-2.

(3) When the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the alternating combination of a bipolar membrane, a nanofiltration membrane, an anode membrane, a bipolar membrane, a nanofiltration membrane and an anode membrane (a combination unit of the bipolar membrane, the nanofiltration membrane and the anode membrane can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, an acid chamber is formed between the bipolar membrane and the nanofiltration membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the nanofiltration membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane: the effect achieved at the moment is the same as that of the conventional three-compartment bipolar membrane, the alkali chamber generates monovalent cations and alkali corresponding to the divalent cations, and the acid chamber generates acid corresponding to the monovalent anions.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination of the bipolar membrane, the nanofiltration membrane, the anode membrane, the bipolar membrane, the nanofiltration membrane and the anode membrane (a combination unit of the bipolar membrane, the nanofiltration membrane and the anode membrane can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, an acid chamber is formed between the bipolar membrane and the nanofiltration membrane according to the sequence of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the nanofiltration membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane: the effect achieved at this time is the same as that of the conventional three-compartment bipolar membrane, the base chamber generates base corresponding to monovalent cation, and the acid chamber generates acid corresponding to monovalent anion, even if the cost of the nanofiltration membrane is much lower than that of the negative membrane, so that the cost reduction is beneficial compared with the replacement of the negative membrane by the nanofiltration membrane for the three-compartment bipolar membrane.

Based on the membrane stack, the membrane stack I-3 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the alternating combination of a bipolar membrane, a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane (a combination unit of 'the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane' can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, an acid chamber is formed between the bipolar membrane and the first nanofiltration membrane, a water inlet chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and an alkali chamber is formed between the second nanofiltration membrane and the bipolar membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate (the specific connection mode and the principle refer to the drawing I-3):

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the second nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent cations) and enter the alkali chamber, and are blocked by the bipolar membrane when moving towards the direction of the electrode negative plate, so that the monovalent cations are left in the alkali chamber;

The divalent cations in the water inlet chamber move towards the direction of the electrode negative plate and cannot pass through the second nanofiltration membrane (the nanofiltration membrane can intercept the divalent cations) and cannot enter the alkali chamber, so that the divalent cations are remained in the water inlet chamber;

monovalent anions in the water inlet chamber move towards the direction of the positive electrode plate of the electrode, pass through the first nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions), enter the acid chamber, and then move towards the direction of the positive electrode plate of the electrode and are blocked by the bipolar membrane, so that the monovalent anions are remained in the acid chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxide radical moves to the positive electrode plate direction and enters the alkali chamber to form corresponding alkali with the univalent cation in the alkali chamber (the hydroxide radical can penetrate the second nanofiltration membrane again, but for the electroneutrality of the univalent cation in the alkali chamber, the hydroxide radical can be paired with the univalent cation in an equivalent weight manner in the alkali chamber to generate the alkali);

the hydrogen ions move towards the electrode negative plate and enter the acid chamber to form corresponding acid with the monovalent anions in the acid chamber (although the hydrogen ions can permeate the first nanofiltration membrane again, the hydrogen ions and the monovalent anions in the acid chamber are equivalent pairs in an equal molar ratio to generate acid in the acid chamber for the purpose of electric neutrality of the monovalent anions in the acid chamber).

And finally, the alkali chamber obtains the alkali corresponding to the monovalent cation, the acid chamber obtains the acid corresponding to the monovalent anion, namely, the alkali chamber product obtained from the aqueous solution containing the monovalent cation, the divalent cation and the monovalent anion only contains the alkali corresponding to the monovalent cation through the treatment of the membrane stack I-3.

(2) When the aqueous solution to be treated contains univalent cations, divalent anions or more and univalent anions, the alternating combination of a bipolar membrane, a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane (a combination unit of 'the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane' can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, an acid chamber is formed between the bipolar membrane and the first nanofiltration membrane, a water inlet chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and an alkali chamber is formed between the second nanofiltration membrane and the bipolar membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate (the specific connection mode and the principle refer to the drawing I-3-1):

divalent anions or more in the water inlet chamber move towards the direction of the positive electrode plate of the electrode and cannot pass through the first nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) and cannot enter the acid chamber, so that the divalent anions or more are remained in the water inlet chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

And finally, the base corresponding to the monovalent cation is obtained in the base chamber, the acid corresponding to the monovalent anion is obtained in the acid chamber, namely, the acid chamber product obtained from the aqueous solution containing the monovalent cation, the divalent anion and the monovalent anion only contains the acid corresponding to the monovalent anion through the treatment of the membrane stack I-3.

(3) When the aqueous solution to be treated contains monovalent cation, divalent cation, monovalent anion and divalent anion, the alternating combination of a bipolar membrane, a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane (a combination unit of the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate to the direction of an electrode negative plate, an acid chamber is formed between the bipolar membrane and the first nanofiltration membrane, a water inlet chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and an alkali chamber is formed between the second nanofiltration membrane and the bipolar membrane according to the sequence of the direction of the electrode positive plate to the direction of the electrode negative plate (the specific connection mode and the principle refer to the drawing I-3-2):

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

Finally, the base corresponding to univalent cations is obtained in the base chamber, the acid corresponding to univalent anions is obtained in the acid chamber, namely, the acid chamber product obtained from the aqueous solution containing univalent cations, divalent cations, monovalent anions and divalent anions only contains the acid corresponding to univalent anions through the treatment of the membrane stack I-3; the resulting base compartment product is a base containing only monovalent anions.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination of the bipolar membrane, the first nanofiltration membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane (a combination unit of the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, an acid chamber is formed between the bipolar membrane and the first nanofiltration membrane, a water inlet chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and an alkali chamber is formed between the second nanofiltration membrane and the bipolar membrane: the effect that reaches this moment is the same with conventional three compartment bipolar membrane, and all be that the alkali room has produced the alkali that monovalent cation corresponds, and the acid room has produced the acid that monovalent anion corresponds, even so, because the nanofiltration membrane cost is much lower than positive membrane, negative membrane, so it is beneficial to cost reduction to change positive membrane, negative membrane with the nanofiltration membrane for three compartment bipolar membrane.

Based on the membrane stack, the membrane stack I-4 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent anions and univalent anions, the alternating combination (the combination unit of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane can be repeated for many times) of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane is distributed in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, an acid chamber I is formed between the bipolar membrane and the nanofiltration membrane, an acid chamber II is formed between the nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, and an alkali chamber is formed between the positive membrane and the bipolar membrane (the specific connection mode and the principle refer to a picture I-4):

Monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the acid chamber II, monovalent anions in the acid chamber II move towards the direction of the electrode positive plate and pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) to enter the acid chamber I, and monovalent anions in the acid chamber I move towards the direction of the electrode positive plate and are blocked by the bipolar membrane, so that monovalent anions are remained in the acid chamber I and the acid chamber II (mainly in the acid chamber I);

divalent anions or more in the water inlet chamber move towards the direction of the electrode positive plate and penetrate through the negative membrane to enter the acid chamber II, and divalent anions or more in the acid chamber II move towards the direction of the electrode positive plate and cannot penetrate through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) and cannot enter the acid chamber I, so that the divalent anions or more are remained in the acid chamber II;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

hydrogen ions move towards the direction of the electrode negative plate and enter the acid chamber I and the acid chamber II, and the hydrogen ions and monovalent anions in the acid chamber I form corresponding acids; the hydrogen ions form corresponding acid with the divalent anions (mainly the divalent anions form corresponding acid, and also contain a small amount of acid corresponding to monovalent anions) in the acid chamber II.

Finally, the base corresponding to univalent cations is obtained in the base chamber, the acid corresponding to univalent anions is obtained in the acid chamber I, the acid corresponding to divalent anions or more is obtained in the acid chamber II (mainly the acid corresponding to the divalent anions or more is formed, and a small amount of acid corresponding to the univalent anions is also contained), namely, the acid chamber I obtained from the aqueous solution containing the univalent cations, the divalent anions or more and the univalent anions through the treatment of the membrane stack I-4 is the acid corresponding to the univalent anions only; the acid chamber II obtains the acid corresponding to the divalent anion (mainly the acid corresponding to the divalent anion is formed, and the acid corresponding to the monovalent anion is also contained in a small amount).

(2) When the aqueous solution to be treated contains monovalent cation, divalent cation, monovalent anion and divalent anion, the alternating combination of a bipolar membrane, a nanofiltration membrane, an anion membrane, an anode membrane, a bipolar membrane, a nanofiltration membrane, an anion membrane and an anode membrane (a combination unit of the bipolar membrane, the nanofiltration membrane, the anion membrane and the anode membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate to the direction of the electrode negative plate, an acid chamber I is formed between the bipolar membrane and the nanofiltration membrane, an acid chamber II is formed between the nanofiltration membrane and the cathode membrane, a water inlet chamber is formed between the anion membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane (the specific connection mode and the principle refer to the drawing I-4-1):

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

Finally, the base chamber obtains univalent cations and bases corresponding to the bivalent cations, the acid chamber I obtains acids corresponding to the univalent anions, the acid chamber II obtains acids corresponding to the bivalent anions (mainly the acids corresponding to the bivalent anions are formed by the bivalent anions and contain a small amount of acids corresponding to the univalent anions), namely, the acid chamber I product obtained from the aqueous solution containing the univalent cations, the bivalent cations, the univalent anions and the bivalent anions through the treatment of the membrane stack I-4 only contains the acids corresponding to the univalent anions; the acid chamber II obtains the acid corresponding to the divalent anion (mainly the acid corresponding to the divalent anion is formed, and the acid corresponding to the monovalent anion is also contained in a small amount).

Based on the membrane stack, the membrane stack I-5 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) When the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the alternating combination (the combination unit of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane can be repeated for many times) of the bipolar membrane, the negative membrane, the positive membrane, the nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, a first alkali chamber is formed between the positive membrane and the nanofiltration membrane, and a second alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to the figure I-5):

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the anode membrane and enter the first alkali chamber, monovalent cations in the first alkali chamber move towards the direction of the electrode negative plate, pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent cations) and enter the second alkali chamber, and monovalent cations in the second alkali chamber are blocked by the bipolar membrane when moving towards the direction of the electrode negative plate, so that monovalent cations are left in the first alkali chamber and the second alkali chamber (mainly in the second alkali chamber);

The divalent cations in the water inlet chamber move towards the electrode negative plate direction, pass through the anode membrane and enter the first alkali chamber, and the divalent cations in the first alkali chamber move towards the electrode negative plate direction and cannot pass through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent cations) and enter the second alkali chamber, so that the divalent cations are remained in the first alkali chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxide radical moves towards the positive electrode plate of the electrode and enters the first alkali chamber and the second alkali chamber, and the hydroxide radical and monovalent cations in the second alkali chamber form corresponding alkali; the hydroxide radical and the divalent cation (more than or equal to the divalent cation) in the first alkali chamber form corresponding alkali (mainly the alkali which corresponds to the divalent cation is formed, and the alkali which corresponds to the monovalent cation with low concentration is also contained);

the hydrogen ions move towards the negative electrode plate of the electrode and enter the acid chamber, and the hydrogen ions and monovalent anions in the acid chamber form corresponding acid.

Finally, the acid corresponding to monovalent anions is obtained in the acid chamber, the alkali corresponding to monovalent cations is obtained in the alkali chamber II, the alkali corresponding to more than or equal to divalent cations is obtained in the alkali chamber I (mainly the alkali corresponding to more than or equal to divalent cations is formed, and the alkali corresponding to low-concentration monovalent cations is also contained), namely, the alkali chamber II product obtained from the water solution containing the monovalent cations, more than or equal to divalent cations and monovalent anions is only the alkali corresponding to monovalent cations after the treatment of the membrane stack I-5; the first alkali chamber obtains alkali corresponding to divalent cation (mainly alkali corresponding to divalent cation formation, and alkali corresponding to low-concentration monovalent cation).

(2) When the aqueous solution to be treated contains univalent cations, bivalent cations, univalent anions and bivalent anions, the alternating combination (the combination unit of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane can be repeated for many times) of the bipolar membrane, the negative membrane, the positive membrane, the nanofiltration membrane, the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate of the electrode to the direction of the negative electrode plate, an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, an alkali chamber is formed between the positive membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to a diagram I-5-1):

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

Finally, the acid chamber obtains acid containing univalent anions and acids corresponding to the bivalent anions or more, the alkali chamber II obtains alkali corresponding to univalent cations, the alkali chamber I obtains alkali corresponding to the bivalent cations or more (mainly the alkali corresponding to the bivalent cations or more is formed, and also contains alkali corresponding to low-concentration univalent cations), namely, through the treatment of the membrane stack I-5, the alkali chamber II product obtained from the aqueous solution containing the univalent cations, the bivalent cations or more, the univalent anions and the bivalent anions or more is only the alkali corresponding to the univalent cations; the first alkali chamber obtains alkali corresponding to divalent cation (mainly alkali corresponding to divalent cation formation, and alkali corresponding to low-concentration monovalent cation).

Based on the membrane stack, the membrane stack I-6 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains monovalent cation, divalent cation or more and monovalent anion, the alternating combination of the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane (the combination unit of the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the electrode positive plate direction → the electrode negative plate direction, an acid chamber II is formed before the bipolar membrane and the first nanofiltration membrane in the sequence of the electrode positive plate direction → the electrode negative plate direction, an acid chamber I is formed between the first nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, an alkali chamber I is formed between the positive membrane and the second membrane, and an alkali chamber II is formed between the second nanofiltration membrane and the bipolar membrane (the specific connection mode and the reference diagram I-6):

Monovalent cations in the water inlet chamber move towards the electrode negative plate direction, pass through the anode membrane and enter the first alkali chamber, monovalent cations in the first alkali chamber move towards the electrode negative plate direction, pass through the second nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent cations) and enter the second alkali chamber, and monovalent cations in the second alkali chamber are blocked by the bipolar membrane when moving towards the electrode negative plate direction, so that monovalent cations are left in the first alkali chamber and the second alkali chamber (mainly in the second alkali chamber);

the divalent cations in the water inlet chamber move towards the electrode negative plate direction, pass through the anode membrane and enter the first alkali chamber, and the divalent cations in the first alkali chamber move towards the electrode negative plate direction and cannot pass through the second nanofiltration membrane (the nanofiltration membrane can intercept the divalent cations) and cannot enter the second alkali chamber, so that the divalent cations are remained in the first alkali chamber;

monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the first acid chamber, monovalent anions in the first acid chamber move towards the direction of the electrode positive plate and pass through the first nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) to enter the second acid chamber, and monovalent anions in the second acid chamber move towards the direction of the electrode positive plate and are blocked by the bipolar membrane, so that monovalent anions are remained in the first acid chamber and the second acid chamber;

The bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydrogen ions move towards the electrode negative plate and enter the acid chamber I and the acid chamber II, and the hydrogen ions and monovalent anions in the acid chamber I and the acid chamber II form corresponding acids.

Finally, the acid corresponding to the monovalent anion is obtained in the acid chamber I and the acid chamber II, the alkali corresponding to the monovalent cation is obtained in the alkali chamber II, the alkali corresponding to the divalent cation or more is obtained in the alkali chamber I (mainly the alkali corresponding to the formation of the divalent cation or more and also the alkali corresponding to the low-concentration monovalent cation is contained), namely, the alkali chamber II product obtained from the aqueous solution containing the monovalent cation, the divalent cation or more and the monovalent anion is the alkali corresponding to the monovalent cation only through the treatment of the membrane stack I-6; the first alkali chamber obtains alkali corresponding to divalent cation (mainly alkali corresponding to divalent cation formation, and alkali corresponding to low-concentration monovalent cation).

(2) When the aqueous solution to be treated contains monovalent cation, divalent anion or more and monovalent anion, the alternating combination of the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane (the combination unit of the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, an acid chamber II is formed before the bipolar membrane and the first nanofiltration membrane in the sequence of the direction of the positive electrode plate → the direction of the negative electrode plate, an acid chamber I is formed between the first nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, a base chamber I is formed between the positive membrane and the second nanofiltration membrane, and a base chamber II is formed between the second nanofiltration membrane and the bipolar membrane (the specific connection mode and the reference picture-6-1):

univalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the anode membrane and enter the first alkali chamber, univalent cations in the first alkali chamber move towards the direction of the electrode negative plate, pass through the second nanofiltration membrane (the nanofiltration membrane cannot intercept univalent cations) and enter the second alkali chamber, and the univalent cations in the second alkali chamber are blocked by the bipolar membrane when moving towards the direction of the electrode negative plate, so the univalent cations are left in the first alkali chamber and the second alkali chamber;

Monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the first acid chamber, monovalent anions in the first acid chamber move towards the direction of the electrode positive plate and pass through the first nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) to enter the second acid chamber, and monovalent anions in the second acid chamber move towards the direction of the electrode positive plate and are blocked by the bipolar membrane, so that monovalent anions are remained in the first acid chamber and the second acid chamber (mainly in the second acid chamber);

divalent anions or more in the water inlet chamber move towards the direction of the electrode positive plate and penetrate through the negative membrane to enter the first acid chamber, and the divalent anions or more in the first acid chamber move towards the direction of the electrode positive plate and cannot penetrate through the first nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) and cannot enter the second acid chamber, so that the divalent anions or more are remained in the first acid chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode to enter the first alkali chamber and the second alkali chamber, and the hydroxyl and monovalent cations in the first alkali chamber and the second alkali chamber form corresponding alkali;

hydrogen ions move towards the direction of the electrode negative plate and enter the acid chamber I and the acid chamber II, and the hydrogen ions and monovalent anions in the acid chamber II form corresponding acid; the hydrogen ions form corresponding acids with the divalent anions (mainly the acid corresponding to the divalent anions and containing low concentration of acid corresponding to the monovalent anions) in the acid chamber I.

Finally, the acid corresponding to the monovalent anion is obtained in the acid chamber II, the acid corresponding to the formation of the divalent anion is obtained in the acid chamber I (mainly the acid corresponding to the formation of the divalent anion is obtained in the acid chamber I, and the acid corresponding to the monovalent anion also contains low-concentration acid corresponding to the monovalent anion), the alkali corresponding to the monovalent cation is obtained in the alkali chamber I and the alkali chamber II, namely, the acid corresponding to the monovalent anion is obtained from the aqueous solution containing the monovalent cation, the divalent anion and the monovalent anion through the treatment of the membrane stack I-6; the acid chamber I obtains the acid corresponding to the divalent anion (mainly the acid corresponding to the divalent anion is formed, and the acid corresponding to the monovalent anion with low concentration is also obtained).

(3) When the aqueous solution to be treated contains monovalent cation, divalent cation, monovalent anion and divalent anion, the alternating combination of a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane and a second nanofiltration membrane (a combination unit of the bipolar membrane, the first nanofiltration membrane, the anion membrane, the anode membrane and the second nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate to the direction of an electrode negative plate, an acid chamber II is formed before the bipolar membrane and the first nanofiltration membrane in the sequence of the direction of the electrode positive plate to the direction of the electrode negative plate, an acid chamber I is formed between the first nanofiltration membrane and the anion membrane, a water inlet chamber I is formed between the anode membrane and the second nanofiltration membrane, and an alkali chamber II is formed between the second nanofiltration membrane and the bipolar membrane (a specific connection mode and a principle reference diagram I-6-2):

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode to enter the first alkali chamber and the second alkali chamber, and the hydroxyl and monovalent cations in the second alkali chamber form corresponding alkali; the hydroxide radical and the divalent cation or more in the first alkali chamber form corresponding alkali (mainly the alkali which forms the corresponding divalent cation or more and also contains alkali corresponding to low-concentration monovalent cation);

Finally, the acid chamber II obtains acid corresponding to monovalent anions, the acid chamber I obtains acid corresponding to formation of divalent anions or more (mainly acid corresponding to formation of divalent anions or more and also acid corresponding to low-concentration monovalent anions), the alkali chamber II obtains alkali corresponding to monovalent cations only, the alkali chamber I obtains alkali corresponding to divalent cations or more (mainly alkali corresponding to formation of divalent cations or more and also alkali corresponding to low-concentration monovalent cations) or more, namely, the alkali chamber II product obtained from aqueous solution containing monovalent cations, divalent cations, monovalent anions and divalent anions or more through the treatment of the membrane stack I-6 only contains alkali corresponding to monovalent cations; the alkali chamber I obtains alkali corresponding to more than or equal to divalent cations (mainly takes alkali corresponding to more than or equal to divalent cations and also contains alkali corresponding to low-concentration monovalent cations); the acid chamber II only contains the acid corresponding to the monovalent anion, and the acid chamber I obtains the acid corresponding to the formation of the divalent anion (mainly the acid corresponding to the formation of the divalent anion is obtained, and the acid corresponding to the monovalent anion is also contained in low concentration).

Based on the membrane stack, the membrane stack II-1 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the alternating combination of a bipolar membrane, a nanofiltration membrane, a bipolar membrane and a nanofiltration membrane (a combination unit of the bipolar membrane and the nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, a water inlet chamber is formed between the bipolar membrane and the nanofiltration membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to a figure II-1):

the divalent cations in the water inlet chamber move towards the electrode negative plate and cannot penetrate through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent cations) to enter the alkali chamber, and the divalent cations are left in the water inlet chamber;

Monovalent anions in the water inlet chamber move towards the positive electrode plate of the electrode and are blocked by the bipolar membrane, so the monovalent anions are remained in the water inlet chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydrogen ions move towards the negative electrode plate of the electrode and enter the water inlet chamber to form corresponding acid (a mixture of acid and salt in the inlet water, namely a small amount of univalent cations and bivalent or more cations) with the remaining anions in the water inlet chamber.

And finally, obtaining the alkali corresponding to the monovalent cation in the alkali chamber, namely obtaining an alkali chamber product from the aqueous solution containing the monovalent cation, the divalent cation and the monovalent anion by treating the membrane stack II-1, wherein the alkali chamber product only contains the alkali corresponding to the monovalent cation.

(2) When the aqueous solution to be treated contains univalent cations, divalent anions, univalent anions and divalent cations, the alternating combination of a bipolar membrane, a nanofiltration membrane, a bipolar membrane and a nanofiltration membrane (a combination unit of the bipolar membrane and the nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate to the direction of an electrode negative plate, a water inlet chamber is formed between the bipolar membrane and the nanofiltration membrane in the sequence of the direction of the electrode positive plate to the direction of the electrode negative plate, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to a diagram II-1-1):

monovalent anions and anions not less than divalent anions in the water inlet chamber move towards the positive electrode plate of the electrode and are blocked by the bipolar membrane, so that the monovalent anions and the anions not less than divalent anions are remained in the water inlet chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydrogen ions move towards the negative electrode plate of the electrode and enter the water inlet chamber to form corresponding acid (a mixture of acid and salt in the inlet water, namely a small amount of univalent cations and bivalent or more cations) with the univalent anions and bivalent or more anions remained in the water inlet chamber.

And finally, obtaining the alkali corresponding to the monovalent cation in the alkali chamber, namely obtaining an alkali chamber product from the aqueous solution containing the monovalent cation, the divalent anion, the monovalent anion and the divalent cation only by treating the membrane stack II-1.

(3) When the aqueous solution to be treated contains univalent cations, divalent anions or more and univalent anions, the alternating combination of a bipolar membrane, a nanofiltration membrane, a bipolar membrane and a nanofiltration membrane (a combination unit of the bipolar membrane and the nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, a water inlet chamber is formed between the bipolar membrane and the nanofiltration membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane: the alkaline chamber generates alkaline corresponding to univalent cation, the water inlet chamber is internally provided with univalent anion, acid and salt corresponding to more than or equal to divalent anion, the achieved effect is the same as that of the conventional bipolar membrane with two compartments, even if the cost of the nanofiltration membrane is much lower than that of the anode membrane, the cost is reduced by using the nanofiltration membrane for replacing the anode membrane compared with the bipolar membrane with two compartments.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination (the combination unit of the bipolar membrane and the nanofiltration membrane can be repeated for many times) of the bipolar membrane, the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the bipolar membrane and the nanofiltration membrane according to the sequence of the electrode positive plate direction → the direction of the electrode negative plate, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane: the base corresponding to univalent cations is generated in the base chamber, the acid and salt corresponding to univalent anions are in the water inlet chamber, the obtained effect is the same as that of the conventional two-compartment bipolar membrane, and even if the cost of the nanofiltration membrane is much lower than that of the anode membrane, the cost is reduced and the advantage is achieved compared with the method that the anode membrane is replaced by the nanofiltration membrane for the two-compartment bipolar membrane.

Based on the membrane stack, the membrane stack II-2 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent anions or more and univalent anions, the alternating combination of nanofiltration membranes, bipolar membranes, nanofiltration membranes and bipolar membranes (a combination unit of 'nanofiltration membranes and bipolar membranes' can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the nanofiltration membranes and the bipolar membranes in the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and an acid chamber is formed between the bipolar membranes (the specific connection mode and the principle refer to a picture II-2):

Univalent cations in the water inlet chamber move towards the direction of the negative electrode plate of the electrode and cannot pass through the bipolar membrane, so the univalent cations are left in the water inlet chamber;

monovalent anions in the water inlet chamber move towards the positive electrode plate of the electrode and pass through the nanofiltration membrane (because the nanofiltration membrane cannot intercept the monovalent anions) to enter the acid chamber;

divalent anions or more in the water inlet chamber move towards the positive electrode plate of the electrode and cannot pass through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) and cannot enter the acid chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode to enter the water inlet chamber, and forms corresponding alkali (a mixture of the alkali and salt in the inlet water, namely a small amount of univalent anions and more than or equal to divalent anions) with the remaining cations in the water inlet chamber;

The acid chamber finally obtains the acid containing the corresponding univalent anions, namely the acid chamber product obtained from the water solution containing univalent cations, divalent anions and univalent anions through the treatment of the membrane stack II-2 only contains the acid corresponding to the univalent anions.

(2) When the aqueous solution to be treated contains monovalent cation, divalent anion, monovalent anion and divalent cation, the alternating combination of nanofiltration membrane, bipolar membrane, nanofiltration membrane and bipolar membrane (the combination unit of nanofiltration membrane and bipolar membrane can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate of the electrode, a water inlet chamber is formed between the nanofiltration membrane and the bipolar membrane in the sequence of the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate of the electrode, and an acid chamber is formed between the bipolar membrane and the nanofiltration membrane (the specific connection mode and the principle refer to the drawing II-2-1):

monovalent anions in the water inlet chamber move towards the direction of the positive electrode plate of the electrode, pass through the nanofiltration membrane (because the monovalent anions can not be intercepted by the nanofiltration membrane) and enter the acid chamber, and are blocked by the bipolar membrane when moving towards the direction of the positive electrode plate of the electrode, so the monovalent anions are remained in the acid chamber;

divalent anions or more in the water inlet chamber move towards the positive electrode plate of the electrode and cannot penetrate through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) to enter the acid chamber, and the divalent anions or more are remained in the water inlet chamber;

Monovalent cations and divalent cations which are not less than the monovalent cations in the water inlet chamber move towards the direction of the negative electrode plate of the electrode and are blocked by the bipolar diaphragm, so that the monovalent cations and the divalent cations which are not less than the monovalent cations are left in the water inlet chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode and enters the water inlet chamber, and corresponding alkali (a mixture of the alkali and salt in the water inlet chamber, namely a small amount of monovalent anion and divalent anion) is formed by the monovalent cation and the divalent cation in the water inlet chamber;

And finally, the acid corresponding to the monovalent anion is obtained in the acid chamber, namely the acid chamber product obtained from the aqueous solution containing the monovalent cation, the divalent anion, the monovalent anion and the divalent cation only contains the acid corresponding to the monovalent anion through the treatment of the membrane stack II-2.

(3) When the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the alternating combination of nanofiltration membranes, bipolar membranes, nanofiltration membranes and bipolar membranes (a combination unit of 'nanofiltration membranes and bipolar membranes' which can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the nanofiltration membranes and the bipolar membranes according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and an acid chamber is formed between the bipolar membranes and the nanofiltration membranes: the acid corresponding to monovalent anion is generated in the acid chamber, the monovalent cation and alkali and salt corresponding to divalent cation are in the water inlet chamber, the obtained effect is the same as that of the conventional bipolar membrane with two compartments, even if the cost of the nanofiltration membrane is much lower than that of the negative membrane, the cost is reduced and the advantage is achieved compared with the method that the nanofiltration membrane is used for replacing the negative membrane for the bipolar membrane with two compartments.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination of nanofiltration membranes, bipolar membranes, nanofiltration membranes and bipolar membranes (a combination unit of 'nanofiltration membranes and bipolar membranes' which can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the nanofiltration membranes and the bipolar membranes according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and an acid chamber is formed between the bipolar membranes and the nanofiltration membranes: the acid corresponding to univalent anions is generated in the acid chamber, the alkali and salt corresponding to univalent cations are in the water inlet chamber, the obtained effect is the same as that of the conventional bipolar membrane with two compartments, and even if the cost of the nanofiltration membrane is much lower than that of the cathode membrane, the cost is reduced and the method is beneficial compared with the method that the nanofiltration membrane is used for replacing the cathode membrane by the bipolar membrane with two compartments.

Based on the membrane stack, the membrane stack II-3 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations and univalent anions, the alternating combination of a bipolar membrane, an anode membrane, a nanofiltration membrane, a bipolar membrane, an anode membrane and a nanofiltration membrane (a combination unit of the bipolar membrane, the anode membrane and the nanofiltration membrane can be repeated for many times) is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate, a water inlet chamber is formed between the bipolar membrane and the anode membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, an alkali chamber I is formed before the anode membrane and the nanofiltration membrane, and an alkali chamber II is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to a picture II-3):

Monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate and pass through the anode membrane to enter the first alkali chamber, monovalent cations in the first alkali chamber move towards the direction of the electrode negative plate and pass through the nanofiltration membrane (monovalent cations cannot be intercepted by the nanofiltration membrane) to enter the second alkali chamber, and monovalent cations in the second alkali chamber are blocked by the bipolar membrane when moving towards the direction of the electrode negative plate, so that monovalent cations are left in the first alkali chamber and the second alkali chamber (mainly in the second alkali chamber);

the divalent cations in the water inlet chamber move towards the electrode negative plate and pass through the anode membrane to enter the first alkali chamber, the divalent cations in the first alkali chamber move towards the electrode negative plate and cannot pass through the nanofiltration membrane (the nanofiltration membrane can intercept the divalent cations) and cannot enter the second alkali chamber, and the divalent cations are left in the first alkali chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode to enter a second alkali chamber, and corresponding alkali is formed by univalent cations in the second alkali chamber; the hydroxide in the second alkali chamber moves towards the positive electrode plate of the electrode to enter the first alkali chamber, and corresponding alkali is formed by the divalent cations (mainly the alkali formed by the divalent cations and a small amount of alkali corresponding to the monovalent cations) in the first alkali chamber;

And finally, the alkali corresponding to the univalent cation is obtained in the second alkali chamber, namely, the second alkali chamber product obtained from the aqueous solution containing the univalent cation, the bivalent cation or more and the univalent anion through the treatment of the membrane stack II-3 only contains the alkali corresponding to the univalent cation, and the first alkali chamber product contains the alkali corresponding to the bivalent cation or more (mainly alkali corresponding to the bivalent cation and a small amount of alkali corresponding to the univalent cation).

(2) When the aqueous solution to be treated contains univalent cations, divalent anions, univalent anions and divalent cations, the alternating combination (the combination unit of the bipolar membrane, the anode membrane and the nanofiltration membrane can be repeated for many times) of the bipolar membrane, the anode membrane, the nanofiltration membrane, the bipolar membrane, the anode membrane and the nanofiltration membrane is arranged in the membrane stack from the direction of the electrode positive plate to the direction of the electrode negative plate, a water inlet chamber is formed between the bipolar membrane and the anode membrane according to the sequence of the electrode positive plate to the electrode negative plate, a first alkali chamber is formed between the anode membrane and the nanofiltration membrane, and a second alkali chamber is formed between the nanofiltration membrane and the bipolar membrane (the specific connection mode and the principle refer to the drawing II-3-1):

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

And finally, obtaining the alkali corresponding to only the monovalent cation in the alkali chamber II, namely treating the membrane stack II-3 to obtain the alkali corresponding to only the monovalent cation in the alkali chamber II from the aqueous solution containing the monovalent cation, divalent anion, monovalent anion and divalent cation, wherein the alkali corresponding to only the monovalent cation is contained in the alkali chamber II, and the alkali corresponding to divalent cation is contained in the alkali chamber I (mainly the alkali corresponding to the divalent cation is formed, and a small amount of alkali corresponding to the monovalent cation is also contained in the alkali chamber I).

Based on the membrane stack, the membrane stack II-4 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent anions and univalent anions, the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate is arranged to contain an alternate combination of a negative membrane, a bipolar membrane, a nanofiltration membrane, a negative membrane, a bipolar membrane and a nanofiltration membrane (a combination unit of the negative membrane, the bipolar membrane and the nanofiltration membrane can be repeated for many times), a water inlet chamber is formed between the negative membrane and the bipolar membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, an acid chamber I is formed before the bipolar membrane and the nanofiltration membrane, and an acid chamber II is formed between the nanofiltration membrane and the negative membrane (the specific connection mode and the principle refer to a figure II-4):

Monovalent cations in the water inlet chamber are blocked by the bipolar diaphragm when moving towards the negative plate of the electrode, so that the monovalent cations are left in the water inlet chamber;

monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the acid chamber II, monovalent anions in the acid chamber II move towards the direction of the electrode positive plate and pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) to enter the acid chamber I, and monovalent anions in the acid chamber I are blocked by the bipolar membrane towards the direction of the electrode positive plate, so that monovalent anions are remained in the acid chamber I and the acid chamber II (mainly in the acid chamber I);

divalent anions or more in the water inlet chamber move towards the direction of the electrode positive plate and penetrate through the negative membrane to enter the acid chamber II, and divalent anions or more in the acid chamber II move towards the direction of the electrode positive plate and cannot penetrate through the nanofiltration membrane (the nanofiltration membrane intercepts the divalent anions or more) and cannot enter the acid chamber I;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode to enter the water inlet chamber, and monovalent cations in the water inlet chamber and corresponding alkali (a mixture of the alkali and salt in the inlet water, namely a small amount of divalent anions or more and monovalent anions) are formed;

Hydrogen ions move towards the direction of the electrode negative plate and enter an acid chamber I and an acid chamber II, and the hydrogen ions and univalent anions form acid corresponding to the univalent anions in the acid chamber I; in the acid chamber II, the hydrogen ions and the divalent anions form acids corresponding to the divalent anions (the acids corresponding to the divalent anions are taken as the main materials, and a small amount of acids corresponding to the monovalent anions are also contained).

And finally, the acid corresponding to the univalent anions is obtained in the first acid chamber, namely the first acid chamber product obtained from the water solution containing the univalent cations, the bivalent anions and the univalent anions through the treatment of the membrane stack II-4 only contains the acid corresponding to the univalent anions, and the second acid chamber product contains the acid corresponding to the bivalent anions and the bivalent anions (mainly containing the acid corresponding to the bivalent anions and the small amount of the acid corresponding to the univalent anions).

(2) When the aqueous solution to be treated contains univalent cations, divalent anions, univalent anions and divalent cations, the membrane stack from the direction of the positive electrode plate of the electrode to the direction of the negative electrode plate is distributed to comprise an alternating combination of a negative membrane, a bipolar membrane, a nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane (a combination unit of the negative membrane, the bipolar membrane and the nanofiltration membrane can be repeated for many times), a water inlet chamber is formed between the negative membrane and the bipolar membrane according to the sequence of the direction of the positive electrode plate of the electrode to the direction of the negative electrode plate, an acid chamber I is formed between the bipolar membrane and the nanofiltration membrane, and an acid chamber II is formed between the nanofiltration membrane and the negative membrane (the specific connection mode and the principle refer to the figure II-4-1):

Monovalent cations and divalent cations are blocked by the bipolar diaphragm when moving towards the electrode negative plate, so that the monovalent cations and the divalent cations are left in the water inlet chamber;

the bipolar membrane operates to generate hydroxyl and hydrogen ions:

the hydroxyl moves towards the positive electrode plate of the electrode to enter the water inlet chamber, and monovalent cations and divalent cations in the water inlet chamber form corresponding alkali (a mixture of the alkali and salt in inlet water, namely, a small amount of divalent anions and monovalent anions);

And finally, the acid corresponding to the univalent anions is obtained in the first acid chamber, namely, the first acid chamber product obtained from the aqueous solution containing the univalent cations, the bivalent anions, the univalent anions and the bivalent cations through the treatment of the membrane stack II-4 only contains the acid corresponding to the univalent anions, and the second acid chamber product contains the acid corresponding to the bivalent anions (mainly containing the acid corresponding to the bivalent anions and a small amount of the acid corresponding to the univalent anions).

Based on the membrane stack, the membrane stack III-1 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, univalent anions and bivalent anions or more, the alternating combination of nanofiltration membranes, positive membranes, nanofiltration membranes and positive membranes (a combination unit of 'nanofiltration membranes and positive membranes' can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate of the electrode, a water inlet chamber is formed between the nanofiltration membranes and the positive membranes in the sequence of the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate of the electrode, and a concentration chamber is formed between the positive membranes and the nanofiltration membranes (the specific connection mode and the principle refer to the figure III-1):

Monovalent anions in the water inlet chamber move towards the direction of the positive electrode plate of the electrode and pass through the nanofiltration membrane (because the monovalent anions can not be intercepted by the nanofiltration membrane) to enter the concentration chamber, and the monovalent anions in the concentration chamber are blocked by the positive membrane when moving towards the direction of the positive electrode plate of the electrode, so the monovalent anions are remained in the concentration chamber;

divalent anions or more in the water inlet chamber move towards the direction of the positive electrode plate of the electrode and cannot penetrate through the nanofiltration membrane to be blocked by the nanofiltration membrane (the nanofiltration membrane can intercept the divalent anions or more) and cannot enter the concentration chamber, so that the divalent anions or more are remained in the water inlet chamber;

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate and pass through the anode membrane sheet to enter the concentration chamber, and monovalent cations in the concentration chamber do not have the barrier effect when moving towards the direction of the electrode negative plate, but cations corresponding to mol equivalent are left in the concentration chamber in order to achieve the electric balance of monovalent anions in the concentration chamber;

the final concentrating chamber obtains a concentrated solution containing univalent cations and univalent anions.

(2) When the aqueous solution to be treated contains monovalent cation, divalent cation, monovalent anion and divalent anion, the alternating combination of the nanofiltration membrane, the positive membrane, the nanofiltration membrane and the positive membrane (the combination unit of the nanofiltration membrane and the positive membrane can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode to the direction of the negative electrode plate of the electrode, a water inlet chamber is formed between the nanofiltration membrane and the positive membrane in the sequence of the direction of the positive electrode plate of the electrode to the direction of the negative electrode plate of the electrode, and a concentration chamber is formed between the positive membrane and the nanofiltration membrane (the specific connection mode and the principle refer to the figure III-1-1):

the divalent cations in the water inlet chamber move towards the electrode negative plate and pass through the anode membrane sheet to enter the concentration chamber, and the divalent cations in the concentration chamber are blocked by the nanofiltration membrane sheet when moving towards the electrode negative plate, so that the divalent cations are remained in the concentration chamber;

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate and pass through the anode membrane sheet to enter the concentration chamber, the nanofiltration membrane sheet has no barrier effect when the monovalent cations in the concentration chamber move towards the direction of the electrode negative plate, but in order to achieve the electric balance of the monovalent anions in the concentration chamber, the sum of the corresponding mol equivalent of monovalent cations + divalent cations larger than or equal to the mol equivalent of monovalent cations needs to be left in the concentration chamber;

The final concentration chamber obtains a concentrated solution containing univalent cations, bivalent cations and univalent anions.

(3) When the aqueous solution to be treated contains univalent cations, univalent anions and bivalent cations, the alternating combination of nanofiltration membranes, positive membranes, nanofiltration membranes and positive membranes (a combination unit of 'nanofiltration membranes and positive membranes' which can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, a water inlet chamber is formed between the nanofiltration membranes and the positive membranes according to the sequence of the direction of the positive electrode plate → the direction of the negative electrode plate, and a concentration chamber is formed between the positive membranes and the nanofiltration membranes: the final concentration chamber obtains a concentrated solution containing univalent cations, divalent cations and univalent anions, the effect is the same as that achieved by the conventional electrodialysis, and even if the cost of the nanofiltration membrane is much lower than that of the negative membrane, the cost is reduced and the method is beneficial to replacing the negative membrane with the nanofiltration membrane of the electrodialysis equipment.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination of nanofiltration membranes, positive membranes, nanofiltration membranes and positive membranes (a combination unit of 'nanofiltration membranes and positive membranes' which can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, a water inlet chamber is formed between the nanofiltration membranes and the positive membranes according to the sequence of the direction of the positive electrode plate → the direction of the negative electrode plate, and a concentration chamber is formed between the positive membranes and the nanofiltration membranes: the final concentration chamber obtains a concentrate containing monovalent cations and monovalent anions, which has the same effect as the conventional electrodialysis, even though the cost of the nanofiltration membrane is much lower than that of the negative membrane, so the cost is reduced and the cost is beneficial to replace the negative membrane with the nanofiltration membrane of the electrodialysis equipment.

Based on the membrane stack, the membrane stack III-2 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the alternating combination of the negative membrane, the nanofiltration membrane, the negative membrane and the nanofiltration membrane (the combination unit of the negative membrane and the nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane in the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and a concentration chamber is formed between the nanofiltration membrane and the negative membrane (the specific connection mode and the principle refer to a figure III-2):

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the nanofiltration membrane (because the monovalent cations can not be intercepted by the nanofiltration membrane) and enter the concentration chamber, and are blocked by the negative membrane when moving towards the direction of the electrode negative plate, so the monovalent cations are remained in the concentration chamber;

the divalent cations (more than or equal to) in the water inlet chamber move towards the direction of the electrode negative plate and cannot pass through the nanofiltration membrane (because the nanofiltration membrane can intercept the divalent cations) and cannot enter the concentration chamber, and the divalent cations (more than or equal to) are left in the water inlet chamber;

Monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the concentration chamber, and monovalent anions in the concentration chamber do not have the blocking effect when moving towards the direction of the electrode positive plate, but corresponding mol equivalent anions are remained in the concentration chamber in order to ensure that monovalent cations in the concentration chamber reach the electric balance;

(2) When the aqueous solution to be treated contains monovalent cation, monovalent anion, divalent anion or divalent cation, the membrane stack comprising an anion membrane, a nanofiltration membrane, an anion membrane and a nanofiltration membrane which are alternately combined (the combination unit of the anion membrane and the nanofiltration membrane can be repeated for many times) is arranged in the direction from the electrode positive plate to the electrode negative plate, a water inlet chamber is formed between the anion membrane and the nanofiltration membrane in the sequence from the electrode positive plate to the electrode negative plate, and a concentration chamber is formed between the nanofiltration membrane and the anion membrane (the specific connection mode and the principle refer to the figure III-2-1):

the divalent anions or more in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the concentration chamber, and the divalent anions or more in the concentration chamber are blocked by the nanofiltration membrane when moving towards the direction of the electrode positive plate, so that the divalent anions or more are remained in the concentration chamber;

monovalent anions in the water inlet chamber move towards the direction of the positive electrode plate of the electrode and pass through the negative membrane to enter the concentration chamber, and when the monovalent anions in the concentration chamber move towards the direction of the positive electrode plate of the electrode, although the nanofiltration membrane has no barrier effect, in order to achieve the electrical balance of monovalent cations in the concentration chamber, the sum of the corresponding mol equivalent of monovalent anions and the divalent anions which are more than or equal to the mol equivalent of monovalent anions needs to be left in the concentration chamber;

the final concentration chamber obtains a concentrated solution containing univalent cations, univalent anions and anions not less than divalent.

(3) When the aqueous solution to be treated contains univalent cations, divalent anions or more and univalent anions, the alternating combination of the negative membrane, the nanofiltration membrane, the negative membrane and the nanofiltration membrane (the combination unit of the negative membrane and the nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the electrode positive plate → the direction of the electrode negative plate, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane according to the sequence of the direction of the electrode positive plate → the direction of the electrode negative plate, and a concentration chamber is formed between the nanofiltration membrane and the negative membrane: the final concentration chamber obtains a concentrated solution containing univalent cations, divalent anions and univalent anions, the effect is the same as that achieved by the conventional electrodialysis, and even if the cost of the nanofiltration membrane is much lower than that of the positive membrane, the cost is reduced and the cost is beneficial to replacing the positive membrane with the nanofiltration membrane of the electrodialysis equipment.

(4) When the aqueous solution to be treated contains univalent cations and univalent anions, the alternating combination of the negative membrane, the nanofiltration membrane, the negative membrane and the nanofiltration membrane (a combination unit of the negative membrane and the nanofiltration membrane which can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane in the sequence of the direction of the positive electrode plate → the direction of the negative electrode plate, and a concentration chamber is formed between the nanofiltration membrane and the negative membrane: the final concentration chamber obtains a concentrate containing monovalent cations and monovalent anions, which has the same effect as the conventional electrodialysis, even though the cost of the nanofiltration membrane is much lower than that of the positive membrane, so the cost is reduced by replacing the positive membrane with the nanofiltration membrane of the electrodialysis equipment.

Based on the membrane stack, the membrane stack III-3 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations and univalent anions, the alternating combination of the negative membrane, the positive membrane, the nanofiltration membrane, the negative membrane, the positive membrane and the nanofiltration membrane (a combination unit of the negative membrane, the positive membrane and the nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate, a water inlet chamber is formed between the negative membrane and the positive membrane according to the sequence of the direction of the positive electrode plate → the direction of the negative electrode plate, a first concentration chamber is formed between the positive membrane and the nanofiltration membrane, and a second concentration chamber is formed between the nanofiltration membrane and the negative membrane (the specific connection mode and the principle refer to the figure III-3):

The divalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the anode membrane and enter the first concentration chamber, and are blocked by the nanofiltration membrane (the nanofiltration membrane can block the divalent cations) when the divalent cations in the first concentration chamber move towards the direction of the electrode negative plate, so that the divalent cations are remained in the first concentration chamber and cannot enter the second concentration chamber;

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the anode membrane and enter the first concentration chamber, monovalent cations in the first concentration chamber pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent cations) when moving towards the direction of the electrode negative plate, and enter the second concentration chamber, and monovalent cations in the second concentration chamber are blocked by the cathode membrane when moving towards the direction of the electrode negative plate, so that monovalent cations exist in the first concentration chamber and the second concentration chamber, and monovalent cations are mainly concentrated in the second concentration chamber;

monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the second concentrating chamber, and the monovalent anions in the second concentrating chamber do not have the blocking effect when moving towards the direction of the electrode positive plate, but monovalent anions corresponding to mol equivalent are remained in the first concentrating chamber and the second concentrating chamber in order that cations in the first concentrating chamber and the second concentrating chamber reach the electric balance;

The first final concentration chamber is a concentrated solution mainly containing divalent cations (a small amount of monovalent cations can be mixed) and monovalent anions; and the final concentration chamber II obtains a concentrated solution containing univalent cations and univalent anions.

(2) When the aqueous solution to be treated contains univalent cations, univalent anions and bivalent anions which are not less than two, the membrane stack arranged in the direction from the electrode positive plate to the electrode negative plate comprises an alternating combination of an anion membrane, an anode membrane, a nanofiltration membrane, an anion membrane, an anode membrane and a nanofiltration membrane (a combination unit of the anion membrane, the anode membrane and the nanofiltration membrane can be repeated for many times), a water inlet chamber is formed between the anion membrane and the anode membrane in the sequence from the electrode positive plate to the electrode negative plate, a concentration chamber I is formed between the anode membrane and the nanofiltration membrane, and a concentration chamber II is formed between the nanofiltration membrane and the cathode membrane (the specific connection mode and the principle refer to the figure III-3-1):

the divalent anions or more in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the second concentration chamber, and the divalent anions or more in the second concentration chamber are blocked by the nanofiltration membrane (the nanofiltration membrane can block the divalent anions or more) when moving towards the direction of the electrode positive plate, so that the divalent anions or more are remained in the second concentration chamber and cannot enter the first concentration chamber;

Monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate, pass through the negative membrane and enter the second concentration chamber, monovalent anions in the second concentration chamber pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) when moving towards the direction of the electrode positive plate and enter the first concentration chamber, and monovalent anions in the first concentration chamber are blocked by the positive membrane when moving towards the direction of the electrode positive plate, so that monovalent anions exist in the first concentration chamber and the second concentration chamber and are mainly concentrated in the first concentration chamber;

monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate and pass through the anode membrane sheet to enter the first concentration chamber, the nanofiltration membrane sheet has no barrier effect when the monovalent cations in the first concentration chamber move towards the direction of the electrode negative plate, but monovalent cations corresponding to mol equivalent are left in the first concentration chamber and the second concentration chamber in order that anions in the first concentration chamber and the second concentration chamber reach electrical balance;

the final concentration chamber II obtains a concentrated solution containing more than or equal to divalent anions (a small amount of monovalent anions can be mixed) and monovalent cations; the first final concentrating chamber obtains a concentrated solution containing univalent cations and univalent anions.

(3) When the aqueous solution to be treated contains monovalent cation, monovalent anion, divalent anion or divalent cation, the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate is arranged to contain an alternating combination of negative membrane, positive membrane, nanofiltration membrane, negative membrane, positive membrane and nanofiltration membrane (the combination unit of negative membrane, positive membrane and nanofiltration membrane can be repeated for many times), a water inlet chamber is formed between the negative membrane and the positive membrane in the sequence of the direction of the positive electrode plate → the direction of the negative electrode plate, a concentration chamber I is formed between the positive membrane and the nanofiltration membrane, and a concentration chamber II is formed between the nanofiltration membrane and the negative membrane (the specific connection mode and the principle refer to the figure III-3-2):

monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate, pass through the negative membrane and enter the second concentration chamber, monovalent anions in the second concentration chamber pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent anions) when moving towards the direction of the electrode positive plate and enter the first concentration chamber, monovalent anions in the first concentration chamber are blocked by the positive membrane when moving towards the direction of the electrode positive plate, monovalent anions exist in the first concentration chamber and the second concentration chamber, and monovalent anions are mainly concentrated in the first concentration chamber;

Monovalent cations in the water inlet chamber move towards the direction of the electrode negative plate and pass through the anode membrane and enter the first concentration chamber, monovalent cations in the first concentration chamber pass through the nanofiltration membrane (the nanofiltration membrane cannot intercept monovalent cations) when moving towards the direction of the electrode negative plate and enter the second concentration chamber, monovalent cations in the second concentration chamber are blocked by the cathode membrane when moving towards the direction of the electrode negative plate, monovalent cations exist in the first concentration chamber and the second concentration chamber, and monovalent cations are mainly concentrated in the second concentration chamber;

in order to achieve the electrical balance of the first concentrating chamber and the second concentrating chamber, the first concentrating chamber is mainly concentrated solution of divalent cations and monovalent anions; the second concentration chamber is mainly concentrated solution of divalent anions and monovalent cations.

Based on the membrane stack, the membrane stack III-4 is preferably used for treating the water solution to be treated with the following water quality, and the effects are achieved as follows:

(1) when the aqueous solution to be treated contains univalent cations, divalent cations or more and univalent anions, the combination of the negative membrane sheet, the positive membrane sheet, the first nanofiltration membrane sheet, the second nanofiltration membrane sheet, the negative membrane sheet, the positive membrane sheet, the first nanofiltration membrane sheet and the second nanofiltration membrane sheet (the combination unit of the negative membrane sheet, the positive membrane sheet, the first nanofiltration membrane sheet and the second nanofiltration membrane sheet can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate of the electrode in the concentration chamber, and the two nanofiltration membrane sheets and one nanofiltration membrane sheet have the same function.

(2) When the aqueous solution to be treated contains monovalent cation, monovalent anion and divalent anion, the combination of the negative membrane sheet, the positive membrane sheet, the first nanofiltration membrane sheet, the second nanofiltration membrane sheet, the negative membrane sheet, the positive membrane sheet, the first nanofiltration membrane sheet and the second nanofiltration membrane sheet (the combination unit of the negative membrane sheet, the positive membrane sheet, the first nanofiltration membrane sheet and the second nanofiltration membrane sheet can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode to the direction of the negative electrode plate, and the two nanofiltration membrane sheets and one nanofiltration membrane sheet have the same function.

(3) When the aqueous solution to be treated contains monovalent cation, monovalent anion, divalent anion or divalent cation, the combination of the negative membrane, the positive membrane, the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane (the combination unit of the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane can be repeated for many times) is arranged in the membrane stack from the direction of the positive electrode plate of the electrode → the direction of the negative electrode plate, a water inlet chamber is formed between the negative membrane and the positive membrane, a first concentration chamber is formed between the positive membrane and the first nanofiltration membrane, a second concentration chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and a third concentration chamber is formed between the second nanofiltration membrane and the negative membrane (the specific connection mode and the principle refer to the diagram III-4):

The divalent anions or more in the water inlet chamber move towards the direction of the electrode positive plate and pass through the negative membrane to enter the third concentration chamber, and the divalent anions or more in the third concentration chamber are blocked by the second nanofiltration membrane (the second nanofiltration membrane can block the divalent anions or more) when moving towards the direction of the electrode positive plate, so that the divalent anions or more are remained in the third concentration chamber and cannot enter the second concentration chamber;

the divalent cations in the water inlet chamber move towards the direction of the electrode negative plate, pass through the anode membrane and enter the first concentration chamber, and are blocked by the first nanofiltration membrane when moving towards the direction of the electrode negative plate, so that the divalent cations are remained in the first concentration chamber and cannot enter the second concentration chamber;

monovalent anions in the water inlet chamber move towards the direction of the electrode positive plate, pass through the negative membrane and enter the third concentration chamber, monovalent anions in the third concentration chamber pass through the second nanofiltration membrane (the second nanofiltration membrane cannot intercept monovalent anions) and enter the second concentration chamber when moving towards the direction of the electrode positive plate, monovalent anions in the second concentration chamber pass through the first nanofiltration membrane (the first nanofiltration membrane cannot intercept monovalent anions) and enter the first concentration chamber when moving towards the direction of the electrode positive plate, and monovalent anions in the first concentration chamber are blocked by the positive membrane when moving towards the direction of the electrode positive plate;

Univalent cations in the water inlet chamber move towards the direction of the electrode negative plate and pass through the anode membrane to enter a first concentration chamber, univalent cations in the first concentration chamber pass through a first nanofiltration membrane (the first nanofiltration membrane cannot intercept univalent cations) when moving towards the direction of the electrode negative plate to enter a second concentration chamber, univalent cations in the second concentration chamber pass through a second nanofiltration membrane (the second nanofiltration membrane cannot intercept univalent cations) when moving towards the direction of the electrode negative plate to enter a third concentration chamber, and univalent cations in the third concentration chamber are blocked by the cathode membrane when moving towards the direction of the electrode negative plate;

the first concentrating chamber is mainly a concentrated solution of monovalent anions and bivalent cations; the third concentrating chamber is mainly a concentrated solution of monovalent cations and divalent anions; the second concentrating chamber mainly comprises monovalent cations and monovalent anions.

Based on the above film stack, it is preferable that the direction from the electrode positive plate to the electrode negative plate includes:

membrane stack I-1-1: nanofiltration membranes, bipolar membranes, negative membranes and nanofiltration membranes (the types and the principles of which are the same as those of the membrane stack I-1 and can be penetrated by ions in the membrane stack I-1-1); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane, the negative membrane and the nanofiltration membrane is replaced by the positive membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane, and the effect is the same; the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-1-2: a negative membrane, a nanofiltration membrane, a bipolar membrane and a negative membrane (the types and the principles of which that each membrane in the membrane stack I-1-2 can transmit ions are the same as those of the membrane stack I-1); or the negative membrane, the nanofiltration membrane, the bipolar membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane: when the anions contained in the aqueous solution to be treated are only monovalent anions, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane; or when the aqueous solution to be treated contains more than or equal to divalent anions, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the negative membrane close to the negative electrode plate with the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

or a membrane stack I-2-1: the membrane comprises an anode membrane, a bipolar membrane, a nanofiltration membrane and an anode membrane (the types and the principles of which are the same as those of the membrane stack I-2 in the membrane stack I-2-1 in a manner that ions can penetrate through the membranes); or the anode membrane, the bipolar membrane, the nanofiltration membrane and the anode membrane close to the electrode positive plate and/or the electrode negative plate in the anode membrane are replaced by the nanofiltration membrane: when the cation contained in the water solution to be treated is only monovalent cation, replacing the positive membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane; or when the aqueous solution to be treated contains more than or equal to divalent cations, replacing the positive membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the positive membrane close to the positive electrode plate with the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-2-2: nanofiltration membranes, positive membranes, bipolar membranes and nanofiltration membranes (the types and the principles of which can be used for penetrating ions in the membrane stack I-2-2 are the same as those of the membrane stack I-2); or the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate in the nanofiltration membrane, the anode membrane, the bipolar membrane and the nanofiltration membrane is replaced by the cathode membrane: when the anions contained in the aqueous solution to be treated are only monovalent anions, replacing the nanofiltration membrane close to the electrode positive plate and/or the electrode negative plate by a negative membrane; or when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

or a membrane stack I-3-1: a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane (the types of ions which can be penetrated by the membranes in the membrane stack I-3-1 are the same as those in the membrane stack I-3 in principle); or the second nanofiltration membrane close to the electrode positive plate and/or the second nanofiltration membrane close to the electrode negative plate in the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane is replaced by an anode membrane: when the cation contained in the aqueous solution to be treated is only monovalent, the second nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the second nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane, and the effect is the same; the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-3-2: a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane and a first nanofiltration membrane (the types and the principles of which are the same as those of the membrane stack I-3 in the membrane stack I-3-2 in which ions can penetrate through the membranes); or the first nanofiltration membrane, the second nanofiltration membrane, the bipolar membrane and the first nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate of the first nanofiltration membrane are replaced by negative membranes: when the anions contained in the aqueous solution to be treated are only monovalent anions, the first nanofiltration membrane close to the electrode positive plate and/or the first nanofiltration membrane close to the electrode negative plate is replaced by a negative membrane; or when the aqueous solution to be treated contains more than or equal to divalent anions, only the first nanofiltration membrane close to the electrode negative plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

or a membrane stack I-4-1: the membrane comprises an anode membrane, a bipolar membrane, a nanofiltration membrane, a cathode membrane and an anode membrane (the types of ions which can be penetrated by the membranes in a membrane stack I-4-1 are the same as those in the membrane stack I-4 in principle); or the positive membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane close to the positive electrode plate and/or the negative electrode plate of the positive membrane are replaced by the nanofiltration membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent cations, replacing the positive membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the positive membrane close to the positive electrode plate with the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-4-2: a negative membrane, a positive membrane, a bipolar membrane, a nanofiltration membrane and a negative membrane (the types and the principles of which are the same as those of the membrane stack I-4 in the membrane stack I-4-2 that can penetrate ions); or the negative membrane, the positive membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent anions, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the negative membrane close to the negative electrode plate with the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

or a membrane stack I-4-3: a nanofiltration membrane, a negative membrane, a positive membrane, a bipolar membrane and a nanofiltration membrane (each membrane in the membrane stack I-4-3 can permeate the types of ions, and the principle is the same as that of the membrane stack I-4); or the nanofiltration membrane, the negative membrane, the positive membrane, the bipolar membrane and the nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate in the nanofiltration membrane are replaced by the negative membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; or when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-5-1: nanofiltration membrane, bipolar membrane, negative membrane, positive membrane and nanofiltration membrane (the types and the principles of which can be used for penetrating ions in the membrane stack I-5-1 are the same as those of the membrane stack I-5); or the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate in the nanofiltration membrane, the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane is replaced by the positive membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; or when the water solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive electrode plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-5-2: a positive membrane, a nanofiltration membrane, a bipolar membrane, a negative membrane and a positive membrane (each membrane in the membrane stack I-5-2 can permeate the types of ions, and the principle is the same as that of the membrane stack I-5); or the positive membrane sheet close to the positive electrode plate and/or the positive membrane sheet close to the negative electrode plate in the positive membrane sheet, the nanofiltration membrane sheet, the bipolar membrane sheet, the negative membrane sheet and the positive membrane sheet are replaced by the nanofiltration membrane sheet: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent cations, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane (but only the positive membrane close to the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-5-3: a negative membrane, a positive membrane, a nanofiltration membrane, a bipolar membrane and a negative membrane (the types and the principles of which are the same as those of the membrane stack I-5 in the membrane stack I-5-3 that can penetrate ions); or the negative membrane, the positive membrane, the nanofiltration membrane, the bipolar membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane (but the negative membrane close to the negative electrode plate can not be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

or a membrane stack I-6-1: a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane and a second nanofiltration membrane (the types and the principles of which are the same as those of the membrane stack I-6 in the membrane stack I-6-1 in a manner that each membrane can permeate ions); or the second nanofiltration membrane close to the electrode positive plate and/or the second nanofiltration membrane close to the electrode negative plate in the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane is replaced by the positive membrane: when the cation contained in the aqueous solution to be treated is only monovalent, the second nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; or when the water solution to be treated contains divalent cations or more, only the second nanofiltration membrane close to the positive electrode plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-6-2: the membrane comprises an anode membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, a cathode membrane and an anode membrane (the types and the principles of which are the same as those of the membrane stack I-6 in the membrane stack I-6-2 in which ions can penetrate through the membranes); or the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate in the positive membrane sheet, the second nanofiltration membrane sheet, the bipolar membrane sheet, the first nanofiltration membrane sheet, the negative membrane sheet and the positive membrane sheet close to the positive electrode plate are replaced by nanofiltration membrane sheets: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; or when the water solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the positive electrode plate can be replaced by the nanofiltration membrane (but the positive membrane close to the positive electrode plate can not be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-6-3: a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a negative membrane (the types of ions which can be penetrated by the membranes in the membrane stack I-6-3 are the same as those in the membrane stack I-6 in principle); or the negative membrane close to the positive electrode plate and/or the negative membrane close to the negative electrode plate in the negative membrane is replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the negative membrane close to the negative electrode plate can not only be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-6-4: the membrane stack comprises a first nanofiltration membrane, a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane and a first nanofiltration membrane (the types and the principles of which are the same as those of the membrane stack I-6 in the membrane stack I-6-4 in a manner that the membranes can permeate ions); or the first nanofiltration membrane, the negative membrane, the positive membrane, the second nanofiltration membrane, the bipolar membrane and the first nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate are replaced by the negative membrane: when the aqueous solution to be treated contains only monovalent anions, the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent anions, the first nanofiltration membrane only close to the electrode negative plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

or a membrane stack II-1-1: nanofiltration membranes, bipolar membranes and nanofiltration membranes (the types and the principles of which can be penetrated by the membranes in the membrane stack II-1-1 are the same as those of the membrane stack II-1); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is replaced by an anode membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane, and the effect is the same; the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack II-2-1: nanofiltration membranes, bipolar membranes and nanofiltration membranes (the types and the principles of which can be penetrated by the membranes in the membrane stack II-2-1 are the same as those of the membrane stack II-2); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is replaced by a negative membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate of the electrode can be replaced by a negative membrane, and the effect is the same; the polar water can be acid corresponding to univalent anion;

or a membrane stack II-3-1: a nanofiltration membrane, a bipolar membrane, an anode membrane and a nanofiltration membrane (the types and the principles of which can be used for penetrating ions by each membrane in the membrane stack II-3-1 are the same as those of the membrane stack II-3); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane, the positive membrane and the nanofiltration membrane is replaced by the positive membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by a positive membrane; the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack II-3-2: the membrane comprises an anode membrane, a nanofiltration membrane, a bipolar membrane and an anode membrane (the types and the principles of which are the same as those of the membrane stack II-3 in the membrane stack II-3-2 in which ions can penetrate through the membranes); or the anode membrane, the nanofiltration membrane, the bipolar membrane and the anode membrane close to the electrode positive plate and/or the electrode negative plate in the anode membrane are replaced by the nanofiltration membrane: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the positive membrane close to the edge of the positive electrode plate can not be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

or a membrane stack II-4-1: a negative membrane, a bipolar membrane, a nanofiltration membrane and a negative membrane (the types and the principles of which that each membrane in the membrane stack II-4-1 can transmit ions are the same as those of the membrane stack II-4); or the negative membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the electrode positive plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the negative membrane close to the edge of the electrode negative plate can not be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

Or a membrane stack II-4-2: a nanofiltration membrane, a negative membrane, a bipolar membrane and a nanofiltration membrane (each membrane in the membrane stack II-4-2 can be used for transmitting the ion type and the principle are the same as those of the membrane stack II-4); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane is replaced by the negative membrane: when the water solution to be treated only contains univalent anions, the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate of the electrode can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

or a membrane stack III-1-1: a positive membrane, a nanofiltration membrane and a positive membrane (the types of ions which can be penetrated by the membranes in the membrane stack III-1-1 are the same as those in the membrane stack III-1 in principle); or the positive membrane sheet close to the positive electrode plate and/or the positive membrane sheet close to the negative electrode plate in the positive membrane sheet, the nanofiltration membrane sheet and the positive membrane sheet are replaced by the nanofiltration membrane sheet: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the positive membrane close to the edge of the positive electrode plate can not be replaced by the nanofiltration membrane); the polar water can be a base corresponding to a monovalent cation or a salt formed by the monovalent anion;

Or a membrane stack III-1-2: a nanofiltration membrane, a positive membrane and a nanofiltration membrane (the types and the principles of which are the same as those of the membrane stack III-1 in the membrane stack III-1-2 which can penetrate ions); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the positive membrane and the nanofiltration membrane is replaced by a negative membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate of the electrode is replaced by a negative membrane; the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

or a membrane stack III-2-1: a negative membrane, a nanofiltration membrane and a negative membrane (the types and the principles of which are the same as those of the membrane stack III-2 in that each membrane in the membrane stack III-2-1 can transmit ions); or the negative membrane, the nanofiltration membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate of the negative membrane are replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the negative membrane close to the negative electrode plate can not be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

Or a membrane stack III-2-2: nanofiltration membranes, negative membranes and nanofiltration membranes (the types and the principles of which are the same as those of the membrane stack III-2 and can be penetrated by ions in the membrane stack III-2-2); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane and the nanofiltration membrane is replaced by the positive membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

or a membrane stack III-3-1: a nanofiltration membrane, a negative membrane, a positive membrane and a nanofiltration membrane (the types and the principles of which are the same as those of the membrane stack III-3 in the membrane stack III-3-1 in which the membranes can permeate ions); or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane, the positive membrane and the nanofiltration membrane is replaced by the positive membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by a positive membrane, and the polar water can be alkali corresponding to monovalent cations or salt formed by monovalent anions; or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane, the positive membrane and the nanofiltration membrane is replaced by the negative membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the polar water can be acid corresponding to monovalent anions or salt formed by monovalent cations;

Or a membrane stack III-3-2: the membrane comprises a positive membrane sheet, a nanofiltration membrane sheet, a negative membrane sheet and a positive membrane sheet (each membrane sheet in a membrane stack III-3-2 can be used for transmitting the types and the principles of ions are the same as those of the membrane stack III-3); or the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate in the positive membrane sheet, the nanofiltration membrane sheet, the negative membrane sheet and the positive membrane sheet close to the positive electrode plate are replaced by the nanofiltration membrane sheet: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent cations, the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate can be replaced by a nanofiltration membrane (but only the positive membrane close to one group of the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

or a membrane stack III-3-3: a negative membrane, a positive membrane, a nanofiltration membrane and a negative membrane (the types and the principles of which that each membrane in the membrane stack III-3-3 can transmit ions are the same as those of the membrane stack III-3); or the negative membrane close to the positive electrode plate and/or the negative membrane close to the negative electrode plate in the negative membrane, the positive membrane, the nanofiltration membrane and the negative membrane are replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but only the negative membrane close to one group of the negative electrode plates can be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

Or a membrane stack III-4-1: a negative membrane, a positive membrane, a first nanofiltration membrane, a second nanofiltration membrane and a negative membrane (each membrane in a membrane stack III-4-1 can be used for transmitting the ion type and the principle are the same as those of the membrane stack III-4); or the negative membrane, the positive membrane, the first nanofiltration membrane, the second nanofiltration membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by nanofiltration membranes: when the water solution to be treated only contains univalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but only the negative membrane close to one group of the negative electrode plates can be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

or a membrane stack III-4-2: the membrane stack comprises a positive membrane, a first nanofiltration membrane, a second nanofiltration membrane, a negative membrane and a positive membrane (the types and the principles of ions which can be penetrated by the membranes in the membrane stack III-4-2 are the same as those of the membrane stack III-4); or the positive membrane sheet close to the positive electrode plate and/or the negative membrane sheet close to the negative electrode plate in the positive membrane sheet, the first nanofiltration membrane sheet, the second nanofiltration membrane sheet, the negative membrane sheet and the positive membrane sheet are replaced by nanofiltration membrane sheets: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent cations, the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate can be replaced by a nanofiltration membrane (but only the positive membrane close to one group of the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

Or a membrane stack III-4-3: a first nanofiltration membrane, a second nanofiltration membrane, a negative membrane, a positive membrane and a first nanofiltration membrane (each membrane in a membrane stack III-4-3 can be used for transmitting the ion type and the principle are the same as those of the membrane stack III-4); or the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate in the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane, the positive membrane and the first nanofiltration membrane are replaced by positive membrane sheets: when the aqueous solution to be treated contains cations only monovalent cations, the first nanofiltration membrane sheet close to the electrode positive plate and/or close to the electrode negative plate can be replaced by an anode membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the first nanofiltration membrane close to the positive plate of the electrode can be replaced by an anode membrane, and the polar water can be alkali corresponding to monovalent cations or salt formed by monovalent anions; or the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate in the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane, the positive membrane and the first nanofiltration membrane is replaced by the negative membrane: when the aqueous solution to be treated contains only monovalent anions, the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, the effect is the same, and the polar water can be acid corresponding to monovalent anions or salt formed by monovalent cations;

Or a membrane stack III-4-4: a second nanofiltration membrane, a negative membrane, a positive membrane, a first nanofiltration membrane and a second nanofiltration membrane (each membrane in a membrane stack III-4-4 can be used for transmitting the ion type and the principle is the same as that of the membrane stack III-4); or the second nanofiltration membrane close to the positive electrode plate and/or the second nanofiltration membrane close to the negative electrode plate in the second nanofiltration membrane, the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane is replaced by the positive membrane: when the aqueous solution to be treated contains cations only monovalent cations, the second nanofiltration membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by an anode membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the second nanofiltration membrane close to the positive electrode plate and/or the second nanofiltration membrane close to the negative electrode plate can be replaced by an anode membrane, the effect is the same, and the polar water can be alkaline corresponding to monovalent cations or salt formed by monovalent anions; or the second nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate in the second nanofiltration membrane, the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane is replaced by the negative membrane: when the aqueous solution to be treated contains only monovalent anions, the second nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the water solution to be treated contains more than or equal to divalent anions, only the second nanofiltration membrane close to the negative electrode plate of the electrode can be replaced by a negative membrane, and the polar water can be acid corresponding to monovalent anions or salt formed by monovalent cations.

Based on the above film stack, preferably, in the direction from the electrode positive plate to the electrode negative plate:

membrane stack I-1: a nanofiltration membrane is added between the positive electrode plate and the first bipolar membrane, the negative membrane and the nanofiltration membrane; or after the nanofiltration membrane is added between the electrode positive plate and the first bipolar membrane, the first negative membrane and the nanofiltration membrane, replacing the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate by the positive membrane: when the cation contained in the water solution to be treated is only monovalent cation, the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane, and the effect is the same; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-1: a negative membrane and a nanofiltration membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the negative membrane and the nanofiltration membrane, and a bipolar membrane and a negative membrane are sequentially added between the last combination of the bipolar membrane, the negative membrane and the nanofiltration membrane and the negative electrode plate; or after the negative membrane and the nanofiltration membrane are sequentially added between the electrode positive plate and the first bipolar membrane, the negative membrane and the nanofiltration membrane, and the negative membrane are sequentially added between the last bipolar membrane, the negative membrane and the nanofiltration membrane and the electrode negative plate, the negative membrane close to the electrode positive plate and/or the negative membrane close to the electrode negative plate is replaced by the nanofiltration membrane: when the anions contained in the aqueous solution to be treated are only monovalent anions, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane; or when the aqueous solution to be treated contains more than or equal to divalent anions, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the negative membrane close to the negative electrode plate with the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-2: an anode membrane is added between the positive electrode plate and the first bipolar membrane, nanofiltration membrane and anode membrane; or after the anode membrane is added between the electrode positive plate and the first bipolar membrane, nanofiltration membrane and anode membrane combination, replacing the anode membrane close to the electrode positive plate and/or the anode membrane close to the electrode negative plate with the nanofiltration membrane: when the cation contained in the water solution to be treated is only monovalent cation, replacing the positive membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane; or when the aqueous solution to be treated contains more than or equal to divalent cations, replacing the positive membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the positive membrane close to the positive electrode plate with the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-2: a nanofiltration membrane and an anode membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the nanofiltration membrane and the anode membrane, and a bipolar membrane and a nanofiltration membrane are sequentially added between the last combination of the bipolar membrane, the nanofiltration membrane and the anode membrane and the negative electrode plate; or the nanofiltration membrane and the anode membrane are sequentially added between the electrode positive plate and the first bipolar membrane, the nanofiltration membrane and the anode membrane, and after the bipolar membrane and the nanofiltration membrane are sequentially added between the last bipolar membrane, the nanofiltration membrane and the anode membrane and the electrode negative plate, the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by the cathode membrane: when the anions contained in the aqueous solution to be treated are only monovalent anions, replacing the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate by a negative membrane; or when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-3: a second nanofiltration membrane is added between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane; or after a second nanofiltration membrane is added between the electrode positive plate and the combination of the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane, the second nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by an anode membrane: when the cation contained in the aqueous solution to be treated is only monovalent, the second nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the second nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane, and the effect is the same; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-3: a first nanofiltration membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane, and a bipolar membrane and a first nanofiltration membrane are sequentially added between the combination of the last bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate; or the first nanofiltration membrane and the second nanofiltration membrane are sequentially added between the electrode positive plate and the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane, the last bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane are sequentially added between the electrode negative plate and the first nanofiltration membrane close to the electrode positive plate and/or the first nanofiltration membrane close to the electrode negative plate after the bipolar membrane and the first nanofiltration membrane are sequentially added: when the anions contained in the aqueous solution to be treated are only monovalent anions, the first nanofiltration membrane close to the electrode positive plate and/or the first nanofiltration membrane close to the electrode negative plate is replaced by a negative membrane; or when the water solution to be treated contains more than or equal to divalent anions, only the first nanofiltration membrane close to the electrode negative plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-4: an anode membrane is added between the positive electrode plate and the first bipolar membrane, nanofiltration membrane, cathode membrane and anode membrane; or after the anode membrane is added between the positive electrode plate and the first bipolar membrane, nanofiltration membrane, cathode membrane and anode membrane combination, replacing the anode membrane close to the positive electrode plate and/or the anode membrane close to the negative electrode plate with the nanofiltration membrane: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent cations, replacing the positive membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the positive membrane close to the positive electrode plate with the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-4: a negative membrane and a positive membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane, and a bipolar membrane, a nanofiltration membrane and a negative membrane are sequentially added between the last combination of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane and the negative electrode plate; or the negative membrane and the positive membrane are sequentially added between the electrode positive plate and the first bipolar membrane, nanofiltration membrane, negative membrane and positive membrane, and the negative membrane and the positive membrane are sequentially added between the last bipolar membrane, nanofiltration membrane, negative membrane and positive membrane and the electrode negative plate, and then the negative membrane close to the electrode positive plate and/or the negative membrane close to the electrode negative plate is replaced by the nanofiltration membrane: when the water solution to be treated only contains univalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent anions, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane (but not replacing only the negative membrane close to the negative electrode plate with the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-4: a nanofiltration membrane, a negative membrane and a positive membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane, and a bipolar membrane and a nanofiltration membrane are sequentially added between the last combination of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane and the negative electrode plate; or the nanofiltration membrane, the negative membrane and the positive membrane are sequentially added between the positive electrode plate and the first bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane, and the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate is replaced by the negative membrane after the bipolar membrane and the nanofiltration membrane are sequentially added between the last bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane and the negative electrode plate: when the water solution to be treated only contains univalent anions, the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate can be replaced by a negative membrane, and the effect is the same; or when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-5: a nanofiltration membrane is added between the positive electrode plate and the first bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane; or after a nanofiltration membrane is added between the electrode positive plate and the first bipolar membrane, negative membrane, positive membrane and nanofiltration membrane, replacing the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate with a positive membrane: when the cation contained in the water solution to be treated is only monovalent cation, the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate can be replaced by an anode membrane, and the effect is the same; or when the water solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive electrode plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-5: an anode membrane and a nanofiltration membrane are sequentially added between the electrode positive plate and the first combination of the bipolar membrane, the cathode membrane, the anode membrane and the nanofiltration membrane, and a bipolar membrane, a cathode membrane and an anode membrane are sequentially added between the last combination of the bipolar membrane, the cathode membrane, the anode membrane and the nanofiltration membrane and the electrode negative plate; or the positive membrane and the nanofiltration membrane are sequentially added between the electrode positive plate and the first combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane, and the positive membrane close to the electrode positive plate and/or the positive membrane close to the electrode negative plate is replaced by the nanofiltration membrane after the last combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane and the electrode negative plate are sequentially added: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent cations, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane (but only the positive membrane close to the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-5: a negative diaphragm, a positive diaphragm and a nanofiltration diaphragm are sequentially added between the positive electrode plate and the first combination of the bipolar diaphragm, the negative diaphragm, the positive diaphragm and the nanofiltration diaphragm, and a bipolar diaphragm and a negative diaphragm are sequentially added between the last combination of the bipolar diaphragm, the negative diaphragm, the positive diaphragm and the nanofiltration diaphragm and the negative electrode plate; or the negative membrane, the positive membrane and the nanofiltration membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane, and the negative membrane and the negative electrode plate are sequentially added between the last combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane and the negative electrode plate, and then the negative membrane close to the positive electrode plate and/or the negative electrode plate is replaced by the nanofiltration membrane: when the water solution to be treated only contains univalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; or when the water solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane (but the negative membrane close to the negative electrode plate cannot be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-6: a second nanofiltration membrane is added between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane; or after a second nanofiltration membrane is added between the electrode positive plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the cathode membrane, the anode membrane and the second nanofiltration membrane, the second nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by the anode membrane: when the aqueous solution to be treated contains cations only monovalent cations, the second nanofiltration membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by an anode membrane sheet, and the effect is the same; or when the water solution to be treated contains divalent cations or more, only the second nanofiltration membrane close to the positive electrode plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack I-6: a positive membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and a bipolar membrane, a first nanofiltration membrane, a negative membrane and a positive membrane are sequentially added between the last combination of the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate; or the positive membrane and the second nanofiltration membrane are sequentially added between the electrode positive plate and the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and the positive membrane close to the electrode positive plate and/or the positive membrane close to the electrode negative plate is replaced by the nanofiltration membrane after the bipolar membrane, the first nanofiltration membrane, the negative membrane and the positive membrane are sequentially added between the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the electrode negative plate: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent cations, the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate can be replaced by a nanofiltration membrane (but not only the positive membrane close to the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack I-6: a negative membrane, a positive membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and a bipolar membrane, a first nanofiltration membrane and a negative membrane are sequentially added between the combination of the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate; or a negative membrane, a positive membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and the negative membrane close to the positive electrode plate and/or the negative electrode plate is replaced by the nanofiltration membrane after the bipolar membrane, the first nanofiltration membrane and the negative membrane are sequentially added between the last bipolar membrane, the combination of the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate: when the water solution to be treated only contains univalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; or when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane (but the negative membrane close to the negative electrode plate cannot be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

Or a membrane stack I-6: a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and a bipolar membrane and a first nanofiltration membrane are sequentially added between the combination of the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate; or after the bipolar membrane and the first nanofiltration membrane are sequentially added between the electrode positive plate and the electrode negative plate, the first nanofiltration membrane and the first negative membrane and the second nanofiltration membrane, the first nanofiltration membrane and the second nanofiltration membrane are replaced by the negative membrane: when the aqueous solution to be treated contains only monovalent anions, the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; or when the water solution to be treated contains more than or equal to divalent anions, the first nanofiltration membrane close to the electrode negative plate can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

Or a membrane stack II-1: a nanofiltration membrane is added between the positive electrode plate and the first bipolar membrane and the first nanofiltration membrane; or replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane after adding the nanofiltration membrane between the positive electrode plate and the first bipolar membrane and nanofiltration membrane combination: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane, and the effect is the same; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack II-2: a nanofiltration membrane is added between the combination of the nanofiltration membrane and the bipolar membrane and the negative electrode plate; or after the nanofiltration membrane is added between the last nanofiltration membrane and the combination of the bipolar membranes and the electrode negative plates, replacing the nanofiltration membrane close to the electrode positive plates and/or close to the electrode negative plates by the negative membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; the polar water can be acid corresponding to univalent anion;

Or a membrane stack II-3: a nanofiltration membrane is added between the positive electrode plate and the first bipolar membrane, the positive membrane and the nanofiltration membrane; or after a nanofiltration membrane is added between the electrode positive plate and the first bipolar membrane, the anode membrane and the nanofiltration membrane, replacing the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate with an anode membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation;

or a membrane stack II-3: an anode membrane and a nanofiltration membrane are sequentially added between the positive electrode plate and the first combination of the bipolar membrane, the anode membrane and the nanofiltration membrane, and a bipolar membrane and an anode membrane are sequentially added between the last combination of the bipolar membrane, the anode membrane and the nanofiltration membrane and the negative electrode plate; or the positive membrane and the nanofiltration membrane are sequentially added between the electrode positive plate and the first bipolar membrane, the positive membrane and the nanofiltration membrane, and the positive membrane close to the electrode positive plate and/or the positive membrane close to the electrode negative plate is replaced by the nanofiltration membrane after the bipolar membrane and the positive membrane are sequentially added between the last bipolar membrane, the positive membrane and the nanofiltration membrane and the electrode negative plate: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the positive membrane close to the edge of the positive electrode plate can not be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation;

Or a membrane stack II-4: a negative membrane is added between the last negative membrane, the combination of the bipolar membrane and the nanofiltration membrane and the negative electrode plate of the electrode; or after the last negative membrane, the combination of the bipolar membrane and the nanofiltration membrane and the negative electrode plates are added, replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the electrode positive plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the negative membrane close to the edge of the electrode negative plate can not be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion;

or a membrane stack II-4: a nanofiltration membrane is added between the positive electrode plate and the combination of the first negative membrane, the bipolar membrane and the nanofiltration membrane; or after the nanofiltration membrane is added between the electrode positive plate and the first negative membrane, the bipolar membrane and the nanofiltration membrane, the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by the negative membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate of the electrode can be replaced by a negative membrane; the polar water can be acid corresponding to univalent anion;

Or a membrane stack III-1: an anode membrane is added between the positive electrode plate and the combination of the first nanofiltration membrane and the anode membrane; or the positive membrane sheet close to the positive electrode plate and/or close to the negative electrode plate after the positive membrane sheet is added between the positive electrode plate and the first nanofiltration membrane sheet and positive membrane sheet combination is replaced by a nanofiltration membrane sheet: when the cation contained in the aqueous solution to be treated is only monovalent cation, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the positive membrane close to the edge of the positive electrode plate can not be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

or a membrane stack III-1: a nanofiltration membrane is added between the combination of the nanofiltration membrane and the anode membrane and the negative electrode plate; or after the nanofiltration membrane is added between the last nanofiltration membrane and the anode membrane and the electrode negative plate, replacing the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate by a cathode membrane: when the water solution to be treated contains only univalent anions, the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate of the electrode is replaced by a negative membrane; the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

Or a membrane stack III-2: a negative membrane is added between the combination of the last negative membrane and the nanofiltration membrane and the negative electrode plate; or after the last negative membrane sheet is added between the combination of the negative membrane sheet and the nanofiltration membrane sheet and the negative electrode plate, replacing the negative membrane sheet close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane sheet: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but the negative membrane close to the negative electrode plate can not be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

or a membrane stack III-2: a nanofiltration membrane is added between the positive electrode plate and the first negative membrane and nanofiltration membrane; or the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by an anode membrane after the nanofiltration membrane is added between the electrode positive plate and the first combination of the cathode membrane and the nanofiltration membrane: when the cation contained in the aqueous solution to be treated is only monovalent cation, the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate can be replaced by an anode membrane, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by the positive membrane; the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

Or a membrane stack III-3: a nanofiltration membrane is added between the positive electrode plate and the first negative membrane, the first positive membrane and the first nanofiltration membrane; or the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by the positive membrane after the nanofiltration membrane is added between the electrode positive plate and the combination of the first negative membrane, the positive membrane and the nanofiltration membrane: when the cation contained in the water solution to be treated is only monovalent cation, the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate can be replaced by an anode membrane, and the effect is the same; when the water solution to be treated contains divalent cations or more, only the nanofiltration membrane close to the positive plate of the electrode can be replaced by an anode membrane, and the polar water can be alkali corresponding to monovalent cations or salt formed by monovalent anions; or the nanofiltration membrane close to the electrode positive plate and/or close to the electrode negative plate is replaced by a negative membrane after the nanofiltration membrane is added between the electrode positive plate and the first negative membrane, the first positive membrane and the nanofiltration membrane: when the water solution to be treated only contains univalent anions, the nanofiltration membrane close to the electrode positive plate and/or the nanofiltration membrane close to the electrode negative plate can be replaced by a negative membrane, and the effect is the same; when the water solution to be treated contains more than or equal to divalent anions, only the nanofiltration membrane close to the negative electrode plate of the electrode can be replaced by a negative membrane, and the polar water can be acid corresponding to monovalent anions or salt formed by monovalent cations;

Or a membrane stack III-3: an anode membrane and a nanofiltration membrane are sequentially added between the positive electrode plate and the first negative membrane, the first positive membrane and the first nanofiltration membrane, and a negative membrane and a positive membrane are sequentially added between the last negative membrane, the last positive membrane and the last nanofiltration membrane and the negative electrode plate; or the positive membrane and the nanofiltration membrane are sequentially added between the positive electrode plate and the first negative membrane, the first positive membrane and the first nanofiltration membrane, and the negative membrane, the last positive membrane and the last nanofiltration membrane and the positive membrane close to the positive electrode plate and/or the negative electrode plate are sequentially added between the negative electrode plate and the last negative membrane and the last positive membrane close to the positive electrode plate are replaced by the nanofiltration membrane: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate can be replaced by a nanofiltration membrane (but only the positive membrane close to one group of the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

Or a membrane stack III-3: a negative membrane is added between the combination of the last negative membrane, the last positive membrane and the last nanofiltration membrane and the negative electrode plate of the electrode; or after the last negative membrane sheet, the combination of the positive membrane sheet and the nanofiltration membrane sheet and the negative electrode plate are added between the negative membrane sheets, replacing the negative membrane sheet close to the positive electrode plate and/or the negative electrode plate with the nanofiltration membrane sheet: when the water solution to be treated only contains univalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but only the negative membrane close to one group of the negative electrode plates can be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

or a membrane stack III-4: a negative membrane is added between the combination of the last negative membrane, the last positive membrane, the first nanofiltration membrane and the last second nanofiltration membrane and the negative electrode plate; or after the last negative membrane, the positive membrane, the combination of the first nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate are added between the negative membrane and the negative electrode plate, the negative membrane close to the positive electrode plate and/or the negative electrode plate is replaced by the nanofiltration membrane: when the water solution to be treated contains only univalent anions as anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the negative membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a nanofiltration membrane (but only the negative membrane close to one group of the negative electrode plates can be replaced by the nanofiltration membrane); the polar water can be acid corresponding to univalent anion or salt formed with univalent cation;

Or a membrane stack III-4: an anode membrane, a first nanofiltration membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first cathode membrane, the first anode membrane, the first nanofiltration membrane and the second nanofiltration membrane, and a cathode membrane and an anode membrane are sequentially added between the combination of the last cathode membrane, the last anode membrane, the last nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate; or the positive electrode plate and the first negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane are sequentially added between the combination of the positive electrode plate and the negative electrode plate, and the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane are sequentially added between the combination of the negative electrode plate and the negative electrode plate, and the negative membrane, the positive membrane and the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate after the positive membrane are sequentially added between the negative electrode plate and the negative electrode plate are replaced by nanofiltration membranes: when the cation contained in the water solution to be treated is only monovalent cation, the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by the nanofiltration membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate can be replaced by a nanofiltration membrane (but only the positive membrane close to one group of the positive electrode plate can be replaced by the nanofiltration membrane); the polar water can be alkaline corresponding to univalent cation or salt formed by univalent anion;

Or a membrane stack III-4: a first nanofiltration membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first negative membrane, the first positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, and a negative membrane, a positive membrane and a first nanofiltration membrane are sequentially added between the combination of the last negative membrane, the last positive membrane, the last first nanofiltration membrane and the last second nanofiltration membrane and the negative electrode plate; or a first nanofiltration membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first negative membrane, the first positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, and the combination of the last negative membrane, the last positive membrane, the last first nanofiltration membrane and the last second nanofiltration membrane and the positive electrode plate are sequentially added between the negative electrode plate and the first nanofiltration membrane which is close to the positive electrode plate and/or the first nanofiltration membrane which is close to the negative electrode plate and is replaced by the positive membrane: when the aqueous solution to be treated contains cations only monovalent cations, the first nanofiltration membrane sheet close to the electrode positive plate and/or close to the electrode negative plate can be replaced by an anode membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, only the first nanofiltration membrane close to the positive plate of the electrode can be replaced by an anode membrane, and the polar water can be alkali corresponding to monovalent cations or salt formed by monovalent anions; or a first nanofiltration membrane and a second nanofiltration membrane are sequentially added between the positive electrode plate and the combination of the first negative membrane, the first positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, and the combination of the last negative membrane, the last positive membrane, the last first nanofiltration membrane and the last second nanofiltration membrane and the negative electrode plate are sequentially added between the negative electrode plate and the first nanofiltration membrane which is close to the positive electrode plate and/or the negative electrode plate and is replaced by the negative membrane: when the aqueous solution to be treated contains only monovalent anions, the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the aqueous solution to be treated contains more than or equal to divalent anions, the first nanofiltration membrane close to the positive electrode plate and/or the first nanofiltration membrane close to the negative electrode plate can be replaced by a negative membrane, the effect is the same, and the polar water can be acid corresponding to monovalent anions or salt formed by monovalent cations;

Or a membrane stack III-4: a second nanofiltration membrane is added between the positive electrode plate and the combination of the first negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane; or after a second nanofiltration membrane is added between the positive electrode plate and the combination of the first negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, the second nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate is replaced by the positive membrane: when the aqueous solution to be treated contains cations only monovalent cations, the second nanofiltration membrane sheet close to the positive electrode plate and/or the negative electrode plate can be replaced by an anode membrane sheet, and the effect is the same; when the aqueous solution to be treated contains divalent cations or more, the second nanofiltration membrane close to the positive electrode plate and/or the second nanofiltration membrane close to the negative electrode plate can be replaced by an anode membrane, the effect is the same, and the polar water can be alkaline corresponding to monovalent cations or salt formed by monovalent anions; or after a second nanofiltration membrane is added between the positive electrode plate and the combination of the first negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, the second nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate is replaced by a negative membrane: when the aqueous solution to be treated contains only monovalent anions, the second nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate can be replaced by a negative membrane, and the effect is the same; when the water solution to be treated contains more than or equal to divalent anions, only the second nanofiltration membrane close to the negative electrode plate of the electrode can be replaced by a negative membrane, and the polar water can be acid corresponding to monovalent anions or salt formed by monovalent cations.

Based on the above stack, it is preferable that the positive electrode plate and the negative electrode plate function as a power supply for supplying a voltage of a dc power supply.

Based on the above membrane stack, it is preferred that, for between the individual membrane sheets:

the membrane stack I-1, the membrane stack I-1-1 or the membrane stack I-1-2 is characterized in that the membrane stack I-1, the membrane stack I-1-1 or the membrane stack I-1-2 is formed by the following steps in the direction of an electrode positive plate → the direction of an electrode negative plate: an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the film stack I-2, the film stack I-2-1 or the film stack I-2-2 is arranged in the direction of the electrode positive plate → the direction of the electrode negative plate: an acid chamber is formed between the bipolar membrane and the nanofiltration membrane, a water inlet chamber is formed between the nanofiltration membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane;

or the film stack I-3, the film stack I-3-1 or the film stack I-3-2 is arranged according to the direction of the electrode positive plate → the direction of the electrode negative plate: an acid chamber is formed between the bipolar membrane and the first nanofiltration membrane, a water inlet chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and an alkali chamber is formed between the second nanofiltration membrane and the bipolar membrane;

or the membrane stack I-4, the membrane stack I-4-1, the membrane stack I-4-2 or the membrane stack I-4-3 are arranged in the direction of an electrode positive plate → the direction of an electrode negative plate: an acid chamber I is formed between the bipolar membrane and the nanofiltration membrane, an acid chamber II is formed between the nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, and an alkali chamber is formed between the positive membrane and the bipolar membrane;

Or the membrane stack I-5, the membrane stack I-5-1, the membrane stack I-5-2 or the membrane stack I-5-3 are arranged in the direction of an electrode positive plate → the direction of an electrode negative plate: an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, a first alkali chamber is formed between the positive membrane and the nanofiltration membrane, and a second alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the membrane stack I-6, the membrane stack I-6-1, the membrane stack I-6-2, the membrane stack I-6-3 or the membrane stack I-6-4 are arranged in the direction of an electrode positive plate → the direction of an electrode negative plate: an acid chamber II is formed between the bipolar membrane and the first nanofiltration membrane, an acid chamber I is formed between the first nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, an alkali chamber I is formed between the positive membrane and the second nanofiltration membrane, and an alkali chamber II is formed between the second nanofiltration membrane and the bipolar membrane;

or the film stack II-1-1 is arranged according to the direction of the electrode positive plate → the direction of the electrode negative plate: a water inlet chamber is formed between the bipolar membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the film stack II-2-1 is arranged according to the direction of the electrode positive plate → the direction of the electrode negative plate: a water inlet chamber is formed between the nanofiltration membrane and the bipolar membrane, and an acid chamber is formed between the bipolar membrane and the nanofiltration membrane;

Or the film stack II-3, the film stack II-3-1 or the film stack II-3-2 is arranged in the direction of the electrode positive plate → the direction of the electrode negative plate: a water inlet chamber is formed between the bipolar membrane and the positive membrane, a first alkali chamber is formed between the positive membrane and the nanofiltration membrane, and a second alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the film stack II-4, the film stack II-4-1 or the film stack II-4-2 is arranged in the direction of the electrode positive plate → the direction of the electrode negative plate: a water inlet chamber is formed between the negative membrane and the bipolar membrane, an acid chamber I is formed in front of the bipolar membrane and the nanofiltration membrane, and an acid chamber II is formed between the nanofiltration membrane and the negative membrane;

or the film stack III-1, the film stack III-1-1 or the film stack III-1-2 is arranged in the direction of the electrode positive plate → the direction of the electrode negative plate: a water inlet chamber is formed between the nanofiltration membrane and the positive membrane, and a concentration chamber is formed between the positive membrane and the nanofiltration membrane;

or the film stack III-2, the film stack III-2-1 or the film stack III-2-2 is arranged in the direction of the electrode positive plate → the direction of the electrode negative plate: a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and a concentration chamber is formed between the nanofiltration membrane and the negative membrane;

or the film stack III-3, the film stack III-3-1, the film stack III-3-2 or the film stack III-3-3 is arranged in the direction of the electrode positive plate → the electrode negative plate: a water inlet chamber is formed between the negative membrane and the positive membrane, a first concentration chamber is formed between the positive membrane and the nanofiltration membrane, and a second concentration chamber is formed between the nanofiltration membrane and the negative membrane;

Or the membrane stack III-4, the membrane stack III-4-1, the membrane stack III-4-2, the membrane stack III-4-3 or the membrane stack III-4-4 are arranged in the direction of an electrode positive plate → the direction of an electrode negative plate: a water inlet chamber is formed between the negative diaphragm and the positive diaphragm, a first concentration chamber is formed between the positive diaphragm and the first nanofiltration membrane, a second concentration chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and a third concentration chamber is formed between the second nanofiltration membrane and the negative diaphragm;

or an electrode water chamber I is formed between the electrode positive plate and a membrane closest to the electrode positive plate, and an electrode water chamber II is formed between the electrode negative plate and a membrane closest to the electrode negative plate (here, the closest membrane is not limited to be a bipolar membrane, an anode membrane, a cathode membrane, a nanofiltration membrane, and the like, and the closest membrane can be referred to as a bipolar membrane, an anode membrane, a cathode membrane, a nanofiltration membrane, and the like as long as the closest membrane is located at the position closest to the electrode positive plate or the electrode negative plate).

Based on the above membrane stack, it is preferable that,

the membrane is closest to the electrode positive plate, ions contained in the water solution in the direction of the electrode negative plate at the joint of the membranes can also penetrate through the membrane to enter the electrode water chamber I according to the valence state of the ions and the characteristic that the negative and positive of the ions correspond to the membrane; similarly, the ion species which can penetrate through the membrane can enter the electrode water chamber II through the membrane according to the ion valence state and the characteristic that the membrane corresponds to the cathode and the anode of the ion contained in the water solution in the direction of the electrode positive plate at the joint of the membrane and the membrane which is closest to the electrode negative plate.

Based on the above membrane stack, it is preferable that,

the most is close to a diaphragm of electrode positive plate and/or is the most close to a diaphragm of electrode negative plate has taken place the replacement of the kind of diaphragm, do not lead to the kind of its room to change, specific:

the membrane type is still the water inlet chamber after the replacement if the position is originally the water inlet chamber, the membrane type is still the concentration chamber after the replacement if the position is originally the concentration chamber, the membrane type is still the concentration chamber one after the replacement if the position is originally the concentration chamber one, the membrane type is still the concentration chamber two after the replacement if the position is originally the concentration chamber three, the membrane type is still the concentration chamber three after the replacement if the position is originally the acid chamber, the membrane type is still the acid chamber one after the replacement if the position is originally the acid chamber one, the membrane type is still the acid chamber two after the replacement if the position is originally the acid chamber two, the membrane type is still the alkali chamber after the replacement if the position is originally the alkali chamber, the membrane type is still the alkali chamber one after the replacement if the position is originally the alkali chamber one, the membrane type is still the alkali chamber two after the replacement if the position is originally the alkali chamber two, the membrane type is still the pole water chamber i after the replacement if the position is originally the pole water chamber i, the membrane type is still the pole water chamber ii after the replacement if the position is pole water chamber ii.

The utility model also discloses an electrodialysis device or a bipolar membrane device, which comprises the membrane stack,

wherein the bipolar membrane equipment is equipment applying a membrane stack containing bipolar membranes, and the membrane stack is as follows:

the membrane stack I-1, the membrane stack I-1-2, the membrane stack I-2-1, the membrane stack I-2-2, the membrane stack I-3-1, the membrane stack I-3-2, the membrane stack I-4-1, the membrane stack I-4-2, the membrane stack I-4-3, the membrane stack I-5-1, the membrane stack I-5-2, the membrane stack I-4-3, the membrane stack I-4-2 the device comprises a film stack I-5-3, a film stack I-6-1, a film stack I-6-2, a film stack I-6-3, a film stack I-6-4, a film stack II-1, a film stack II-2-1, a film stack II-3-1, a film stack II-3-2, a film stack II-4-1 or a film stack II-4-2;

wherein the electrodialysis device is a device applying a membrane stack without bipolar membranes, the membrane stack being:

the membrane stack III-1, the membrane stack III-1-2, the membrane stack III-2-1, the membrane stack III-2-2, the membrane stack III-3-1, the membrane stack III-3-2, the membrane stack III-3-3, the membrane stack III-4-1, the membrane stack III-4-2, the membrane stack III-4-3 or the membrane stack III-4-4.

Based on the above electrodialysis apparatus or bipolar membrane apparatus, it is preferable,

For the water inlet chamber, an outlet of the water inlet chamber is connected to an inlet of the water inlet tank, an outlet of the water inlet tank is connected to the water inlet circulating pump, and an outlet of the water inlet circulating pump is connected to an inlet of the water inlet chamber to form circulation;

or for the concentration chamber, the outlet of the concentration chamber is connected to the inlet of a concentration tank, the outlet of the concentration tank is connected to a concentration circulating pump, and the outlet of the concentration circulating pump is connected to the inlet of the concentration chamber to form a circulation;

or for the first concentration chamber, the outlet of the first concentration chamber is connected to the inlet of the first concentration tank, the outlet of the first concentration tank is connected to the first concentration circulating pump, and the outlet of the first concentration circulating pump is connected to the inlet of the first concentration chamber to form a circulation;

or for the second concentration chamber, the outlet of the second concentration chamber is connected to the inlet of the second concentration tank, the outlet of the second concentration tank is connected to the second concentration circulating pump, and the outlet of the second concentration circulating pump is connected to the inlet of the second concentration chamber to form circulation;

or for the third concentration chamber, the outlet of the third concentration chamber is connected to the inlet of the third concentration tank, the outlet of the third concentration tank is connected to the third concentration circulating pump, and the outlet of the third concentration circulating pump is connected to the inlet of the third concentration chamber to form circulation;

or for the acid chamber, the outlet of the acid chamber is connected to the inlet of the acid tank, the outlet of the acid tank is connected to the acid circulating pump, and the outlet of the acid circulating pump is connected to the inlet of the acid chamber to form a circulation;

Or for the first acid chamber, the outlet of the first acid chamber is connected to the inlet of the first acid tank, the outlet of the first acid tank is connected to the first acid circulating pump, and the outlet of the first acid circulating pump is connected to the inlet of the first acid chamber to form a circulation;

or for the second acid chamber, the outlet of the second acid chamber is connected to the inlet of the second acid tank, the outlet of the second acid tank is connected to the second acid circulating pump, and the outlet of the second acid circulating pump is connected to the inlet of the second acid chamber to form circulation;

or for the alkali chamber, the outlet of the alkali chamber is connected to the inlet of the alkali tank, the outlet of the alkali tank is connected to the alkali circulating pump, and the outlet of the alkali circulating pump is connected to the inlet of the alkali chamber to form a circulation;

or for the first alkali chamber, the outlet of the first alkali chamber is connected to the inlet of the first alkali tank, the outlet of the first alkali tank is connected to the first alkali circulating pump, and the outlet of the first alkali circulating pump is connected to the inlet of the first alkali chamber to form a circulation;

or for the second alkali chamber, the outlet of the second alkali chamber is connected to the inlet of the second alkali tank, the outlet of the second alkali tank is connected to the second alkali circulating pump, and the outlet of the second alkali circulating pump is connected to the inlet of the second alkali chamber to form circulation;

or for the polar water chamber I, the outlet of the polar water chamber I is connected to the inlet of the polar water tank I, the outlet of the polar water tank I is connected to the polar water circulating pump I, and the outlet of the polar water circulating pump I is connected to the inlet of the polar water chamber I to form circulation;

Or for the polar water chamber II, the outlet of the polar water chamber II is connected to the inlet of the polar water tank II, the outlet of the polar water tank II is connected to the polar water circulating pump II, and the outlet of the polar water circulating pump II is connected to the inlet of the polar water chamber II to form circulation;

or for the polar water chamber I, the outlet of the polar water chamber I is connected to the inlet of the polar water tank, the outlet of the polar water tank is connected to the polar water circulating pump, and the outlet of the polar water circulating pump is connected to the inlet of the polar water chamber I to form circulation; for the polar water chamber II, the outlet of the polar water chamber II is connected to the inlet of the polar water tank, the outlet of the polar water tank is connected to the polar water circulating pump, the outlet of the polar water circulating pump is connected to the inlet of the polar water chamber II to form circulation, and the polar water chamber I and the polar water chamber II share one set of the polar water tank and the polar water pump.

the polar water chamber I can be independently provided with a set of polar water tank and a polar water pump; the polar water chamber II can be independently provided with a set of polar water tank and a polar water pump, namely polar water in the polar water chamber I is not mixed with polar water in the polar water chamber II;

or the polar water chamber I and the polar water chamber II can share one set of polar water tank and polar water pump, namely polar water in the polar water chamber I is mixed with polar water in the polar water chamber II.

to concentrated jar, concentrated jar one, concentrated jar two or concentrated jar three, be provided with inlet tube, discharge port (generally the overflow mouth), to concentrated jar, concentrated jar one, concentrated jar two or concentrated jar three replenishment pure water, discharge the concentrate: because ions are continuously input into the concentration chamber, the first concentration chamber, the second concentration chamber or the third concentration chamber, the concentration of the concentrated solution in the concentration tank, the first concentration tank, the second concentration tank or the third concentration tank is higher and higher, the concentrated solution needs to be discharged as a concentrated solution product, in order to control the concentration of the concentrated solution of the product with stable concentration, the general design is to add pure water into the concentration tank, the first concentration tank, the second concentration tank or the third concentration tank to control the water quantity, ensure the fixed volume expansion of the concentration of the concentrated solution in the concentration tank, the first concentration tank, the second concentration tank or the third concentration tank, and overflow the concentrated solution of the product with fixed concentration as the product in an overflow mode of the concentration tank, the first concentration tank, the second concentration tank or the third concentration tank;

or the acid tank, the first acid tank or the second acid tank is provided with a water inlet pipe and a discharge port (generally an overflow port), pure water is supplemented to the acid tank, the first acid tank or the second acid tank, and acid liquor is discharged: because ions continuously come into the acid chamber, the acid chamber I or the acid chamber II to combine into acid, the concentration of the acid in the acid tank, the acid tank I or the acid tank II is higher and higher, the acid needs to be discharged to be used as an acid product, in order to control the concentration of the product acid with stable concentration, the general design is to add pure water into the acid tank, the acid tank I or the acid tank II by controlling the water quantity, ensure the concentration of the acid in the acid tank, the acid tank I or the acid tank II to be expanded in a fixed volume, and collect the product acid overflow with fixed concentration as a product in an overflow mode of the acid tank, the acid tank I or the acid tank II;

Or to alkali jar, alkali jar one or alkali jar two, be provided with inlet tube, discharge port (generally be the overflow mouth), to alkali jar, alkali jar one or two supplementary pure water in alkali jar, discharge out alkali lye: the method is characterized in that ions are continuously fed into an alkali chamber, an alkali chamber I or an alkali chamber II to combine into alkali, so that the concentration of the alkali in an alkali tank, an alkali tank I or an alkali tank II is higher and higher, the alkali needs to be discharged to be used as an alkali product, in order to control the concentration of the product alkali with stable concentration, pure water is generally added into the alkali tank, the alkali tank I or the alkali tank II by controlling the water quantity, the alkali concentration in the alkali tank, the alkali tank I or the alkali tank II is ensured to be expanded in a fixed volume, and the product alkali overflow with fixed concentration is collected as a product in an overflow mode of the alkali tank, the alkali tank I or the alkali tank II;

or for the water inlet tank, a water inlet pipe and a discharge port (generally an overflow port) are provided, the water inlet tank is supplemented with a target aqueous solution to be treated, the supplemented aqueous solution is also supplemented with ions, and a part of treated aqueous solution is discharged from the water inlet tank, specifically:

(1) <xnotran> Ⅰ -1, Ⅰ -1-1, Ⅰ -1-2, Ⅰ -2, Ⅰ -2-1, Ⅰ -2-2, Ⅰ -3, Ⅰ -3-1, Ⅰ -3-2, Ⅰ -4, Ⅰ -4-1, Ⅰ -4-2, Ⅰ -4-3, Ⅰ -5, Ⅰ -5-1, Ⅰ -5-2, Ⅰ -5-3, Ⅰ -6, Ⅰ -6-1, Ⅰ -6-2, Ⅰ -6-3, Ⅰ -6-4, Ⅲ -1, Ⅲ -1-1, Ⅲ -1-2, Ⅲ -2, Ⅲ -2-1, Ⅲ -2-2, Ⅲ -3, Ⅲ -3-1, Ⅲ -3-2, Ⅲ -3-3, Ⅲ -4, Ⅲ -4-1, Ⅲ -4-2, Ⅲ -4-3, Ⅲ -4-4 , , , , , , </xnotran> Therefore, a part of the light salt water with reduced ion concentration is overflowed from the water inlet tank in an overflow mode;

(2) For the water inlet chambers corresponding to the membrane stack II-1, the membrane stack II-1-1, the membrane stack II-2-1, the membrane stack II-3-1, the membrane stack II-3-2, the membrane stack II-4-1 or the membrane stack II-4-2, because some ions in the water inlet chambers are reduced and lost all the time (for example, univalent anions are reduced and replaced by equal mol of hydroxide ions or monovalent cations are reduced and replaced by equal mol of hydrogen ions), although the total ion concentration of the water inlet chambers is not obviously changed (the electric conductivity is not changed greatly and can not be obviously reduced), the ions in the water inlet chambers and even some ions in the water inlet tank are reduced and lost and must be supplemented all the time, the target aqueous solution to be treated needs to be supplemented, so as to supplement the amount of the lost ions, and the overflow of the target aqueous solution to be treated can expand after the volume of the target aqueous solution to be treated, the overflow tank needs to be partially reduced the overflow of the aqueous solution;

or the polar water tank, the polar water tank I or the polar water tank II is provided with a water inlet pipe.

a partition plate is arranged in the water inlet tank, a water inlet pipe (for supplementing water solution to be treated) of the water inlet tank is arranged at one side, a backwater and an overflow port of the water inlet chamber are arranged at the other side, and ions are supplemented into the water inlet tank by the water inlet pipe, so that the ion concentration of the water solution to be treated, which is supplemented into the water inlet pipe, is higher, the ion concentration of the backwater of the water inlet chamber is low, the partition plate has the function of separating the high-concentration water solution, which is supplemented into the water inlet pipe, from the backwater of the low-concentration water inlet chamber (overflow overflows from the backwater side of the water inlet chamber), so that the direct overflow discharge of the high-concentration water solution, which is just supplemented into the water inlet pipe, is avoided, and the two sides are locally communicated (refer to figure IV-1 specifically);

Or the concentration tank, the first concentration tank, the second concentration tank or the third concentration tank is provided with a partition board, the water inlet pipe (for supplementing pure water or for supplementing water solution to be treated) of the first concentration tank, the second concentration tank or the third concentration tank is arranged on one side, the backwater and the overflow port of the concentration chamber, the first concentration chamber, the second concentration chamber or the third concentration chamber are arranged on the other side, the ion concentration of the backwater supplemented from the water inlet pipe is low, and the ion concentration of the backwater of the concentration chamber, the first concentration chamber, the second concentration chamber or the third concentration chamber is high (the overflow overflows from the backwater side of the concentration chamber, the first concentration chamber, the second concentration chamber or the third concentration chamber), so that concentrated solution is obtained, the partition board aims to avoid direct overflow discharge of the low-concentration water supplemented from the water inlet pipe, reduce the concentration of the concentrated solution, and the two sides are locally communicated (refer to figure IV-2, figure IV-3, figure IV-4 and figure IV-5);

the acid tank, the first acid tank or the second acid tank are internally provided with a partition plate, a pure water inlet pipe of the acid tank, the first acid tank or the second acid tank is arranged on one side, a backwater and an overflow port of the acid chamber, the first acid chamber or the second acid chamber are arranged on the other side, pure water is supplied from the water inlet pipe, the ion concentration of the backwater of the acid chamber, the first acid chamber or the second acid chamber is high (overflow overflows from the backwater side of the acid chamber, the first acid chamber or the second acid chamber), and the aim is to obtain concentrated acid liquor, so that the partition plate aims to avoid direct overflow discharge of the pure water supplied by the water inlet pipe, the concentration of the acid liquor is reduced, and the two sides are locally communicated (specifically refer to an IV-6 graph, an IV-7 graph and an IV-8 graph);

The partition plate is arranged in the alkali tank, the first alkali tank or the second alkali tank, a pure water inlet pipe of the first alkali tank or the second alkali tank is arranged on one side, a backwater and an overflow port of the first alkali chamber or the second alkali chamber are arranged on the other side, pure water is supplied from the water inlet pipe, the ion concentration of the backwater of the first alkali chamber or the second alkali chamber is high (overflow overflows from the backwater side of the first alkali chamber or the second alkali chamber), concentrated alkali liquor is obtained, the purpose of the partition plate is to avoid direct overflow discharge of the pure water supplied by the water inlet pipe, the concentration of the alkali liquor is reduced, and two sides are locally communicated (specifically refer to the figures IV-9, IV-10 and IV-11).

Based on the technical scheme, preferably, the left side and the right side of any membrane are provided with the partition boards between the membranes; the purpose of the partition is to separate the devices (such as the membrane and the membrane, and the membrane and the electrode plate) on both sides of the partition into a space, and the partition is provided with a water flow.

Based on the technical scheme, preferably, the nanofiltration membrane allows monovalent anions and monovalent cations to permeate through the membrane, and has the function of blocking (intercepting) the divalent cations and divalent anions, for example, hydrogen ions and hydroxyl ions are monovalent ions and can permeate through the nanofiltration membrane; according to the operation principle of the nanofiltration membrane, some nanofiltration membranes only aim at intercepting divalent or more cations, and some nanofiltration membranes only aim at intercepting divalent or more anions.

Based on the technical scheme, preferably, the cation membrane is a cation exchange membrane which allows cations to permeate and has the function of blocking (intercepting) anions; the anion membrane is an anion exchange membrane which allows anions to permeate and has the function of obstructing (intercepting) cations;

based on the technical scheme, preferably, the hydrogen ions can permeate the positive membrane but cannot permeate the negative membrane and the bipolar membrane; the hydroxide ions can permeate the negative membrane but can not permeate the positive membrane and the bipolar membrane.

Based on the technical scheme, preferably, the positive electrode plate can attract anions including hydroxide ions; the electrode negative plates are capable of attracting cations, including hydrogen ions.

Based on the technical scheme, preferably, the positive electrode plate is connected to a direct current positive power supply; the negative electrode plate is connected to a direct current negative power supply to supply power.

Based on the above technical solutions, preferably, the membrane stack further includes conventional components such as a fixing member, a pressing member, a sealing member, etc., common components, existing components, etc. (i.e., the membrane stack further includes common components used in a conventional electrodialysis membrane stack, a conventional two-compartment bipolar membrane stack, and a conventional three-compartment bipolar membrane stack), so as to complete the assembly of the membrane stack.

Based on the technical scheme, preferably, for the water inlet chamber, the acid chamber, the alkali chamber, the acid chamber I, the acid chamber II, the alkali chamber I, the alkali chamber II, the concentration chamber I, the concentration chamber II or the concentration chamber III, insoluble substances cannot be crystallized and separated out from the water solution to be treated or products in each chamber generated in the treatment process, and an applicable membrane stack and equipment need to be selected according to the materials to be treated and the properties of the products.

The utility model also discloses a water treatment system, which comprises the electrodialysis equipment or the bipolar membrane equipment; the electrodialysis equipment or bipolar membrane equipment is the electrodialysis equipment or bipolar membrane equipment corresponding to various membrane stacks.

Based on the above water treatment system, it is preferable that,

the water solution supply pipeline is connected to a water inlet pipe of a water inlet tank of the electrodialysis device, namely, the electrodialysis device treats the water solution provided by the water solution supply pipeline;

or the water solution supply pipeline is connected to the water inlet pipe of the water inlet tank of the bipolar membrane equipment, namely the bipolar membrane equipment of the utility model is used for treating the water solution provided by the water solution supply pipeline;

or the water treatment system is: an aqueous solution supply pipe (supplying an aqueous solution to be treated) is connected to an inlet pipe of a water inlet tank of the electrodialysis apparatus, a discharge port of a concentration tank two or a discharge port of a concentration tank three of the electrodialysis apparatus, an inlet pipe of a water inlet tank of the bipolar membrane apparatus or an inlet pipe of the bipolar membrane apparatus'. The bipolar membrane equipment of the utility model is new bipolar membrane equipment constructed by various membrane stacks; the bipolar membrane equipment' refers to conventional bipolar membrane equipment, and a membrane stack of the bipolar membrane equipment comprises a bipolar membrane and a negative membrane and/or a positive membrane (the membrane stack of the utility model is not applied);

Or the water treatment system is: the water solution supply line is connected to the water inlet of concentrated unit, the concentrate exit linkage of concentrated unit is in the inlet tube of the water inlet jar of bipolar membrane equipment, bipolar membrane equipment is referring to having applied the utility model discloses a bipolar membrane equipment of various membrane piles.

Based on the above water treatment system, it is preferable that the aqueous solution treated by the water treatment system is an aqueous solution containing divalent cations and/or divalent anions.

Based on the above water treatment system, it is preferable that a tail gas absorption device (such as a tail gas washing tower, a tail gas spray tower, etc.) is further provided,

the water solution discharge pipeline of the tail gas absorption device is connected to the water solution supply pipeline, namely, the target object treated by the water treatment system is the water solution discharged by the water solution discharge pipeline of the tail gas absorption device.

Based on the above water treatment system, preferably, the tail gas absorption equipment may be a tail gas absorption tank (tail gas directly contacts with absorption liquid in the tank), a tail gas absorption tower (tail gas directly contacts with absorption liquid in the tower), a tail gas spray absorption tower (tail gas is sprayed with absorption liquid), a tail gas circulation spray absorption tower (tail gas is sprayed with absorption liquid, and absorption liquid is circulated and sprayed with a pump), and the like.

Based on the above water treatment system, it is preferable that the absorption of a part of the substances in the exhaust gas by the absorption liquid forms an aqueous solution in the exhaust gas absorption device, and the absorption liquid comprises: an alkaline absorption liquid, an acidic absorption liquid or water is used as the absorption liquid, and the alkaline absorption liquid or water is generally used as the absorption liquid when the substance contained in the exhaust gas reacts with the alkaline substance to generate salt (for example, when the water treatment contains the acidic substance); generally, when the substance contained in the tail gas reacts with the acidic substance to generate salt (for example, when the tail gas contains the alkaline substance), the acidic absorption liquid or water is used as the absorption liquid;

based on the above water treatment system, it is preferable that the common alkaline absorption liquid is an aqueous solution of hydroxide, carbonate, bicarbonate, or the like;

based on the above water treatment system, it is preferable that cations of common hydroxides, carbonates, bicarbonates, such as sodium ions, potassium ions, and the like.

Based on the above water treatment system, common acidic absorption liquids are preferably organic acids, hydrochloric acid, sulfuric acid, nitric acid, and the like.

Based on above water treatment system, preferably, still be equipped with and add alkali unit or heating unit:

the outlet of the alkali adding unit is connected to the aqueous solution supply pipeline; or the aqueous solution supply pipeline is provided with an alkalization tank, and an outlet of the alkalization unit is connected to an inlet of the alkalization tank; the alkali adding unit can be an alkali adding pipeline (providing alkali liquor), an alkali adding tank matched with an alkali adding pump and the like, and the source of the alkali liquor can be fresh alkali liquor or alkali liquor generated by the bipolar membrane equipment or the bipolar membrane equipment; the purpose of adding alkali is to convert bicarbonate in the aqueous solution into carbonate by adding alkali, wherein the carbonate is divalent anion and forms a compound state difference with the conventional monovalent anion;

Based on the above water treatment system, preferably, the inlet of the alkali adding unit is connected to an alkali tank or an alkali pipeline, an alkali tank overflow port of the bipolar membrane equipment, an alkali tank first overflow port, an alkali tank second overflow port or an alkali generating tank of the bipolar membrane equipment';

based on the above water treatment system, it is preferable that,

the pH value of the aqueous solution after the alkali addition is used for automatically monitoring and controlling the amount of the added alkali.

Based on the above water treatment system, preferably, a stirring device is arranged in the alkalization tank.

Based on the above water treatment system, it is preferable that the stirring means include a stirrer, compressed gas stirring, or the like.

Or a heating unit is arranged on the water solution supply pipeline, and the purpose of heating is to convert bicarbonate in the water solution into carbonate by heating when the bicarbonate is contained in the water solution, wherein the carbonate is divalent anion and forms a difference of chemical states with the conventional monovalent anion.

Based on the above water treatment system, preferably, the heating unit can be a heating heat exchanger or a heating tank, a heater is arranged in the heating tank, and the upper part of the heating tank is evacuated.

Based on the above water treatment system, it is preferable that the heating unit is followed by a decarbonizing tower, or a decarbonizing tower and a cooler.

Based on above water treatment system, it is preferred, still be equipped with the acidification unit:

the outlet of the acidification unit is connected to a pipeline between the aqueous solution supply pipeline and the water inlet pipe of the water inlet tank of the bipolar membrane device; or an acidification tank is arranged on a pipeline between the aqueous solution supply pipeline and a water inlet pipe of a water inlet tank of the bipolar membrane equipment, and an outlet of the acidification unit is connected to an inlet of the acidification tank;

or the outlet of the acid adding unit is connected to a pipeline between the concentrated solution outlet of the concentrating unit and the water inlet pipe of the water inlet tank of the bipolar membrane device; or an acidification tank is arranged on a pipeline between the concentrated solution outlet of the concentration unit and the water inlet pipe of the water inlet tank of the bipolar membrane equipment, and the outlet of the acid adding unit is connected to the inlet of the acidification tank;

or the outlet of the acid adding unit is connected to a pipeline between the discharge outlet of a concentration tank, a discharge outlet of a concentration tank II or a discharge outlet of a concentration tank III of the electrodialysis equipment and the water inlet pipe of the water inlet tank of the bipolar membrane equipment; or an acidification tank is arranged on a pipeline between a discharge port of a concentration tank, a discharge port of a concentration tank II or a discharge port of a concentration tank III of the electrodialysis equipment and a water inlet pipe of a water inlet tank of the bipolar membrane equipment, and an outlet of an acid adding unit is connected to an inlet of the acidification tank;

Or the outlet of the acid adding unit is connected to a pipeline between the discharge outlet of the concentration tank, the discharge outlet of the concentration tank II or the discharge outlet of the concentration tank III of the electrodialysis device and the water inlet of the bipolar membrane device'; or an acidification tank is arranged on a pipeline between a discharge port of a concentration tank, a discharge port of the concentration tank, a discharge port of a concentration tank II or a discharge port of a concentration tank III of the electrodialysis equipment and a water inlet of the bipolar membrane equipment, and an outlet of an acid adding unit is connected to an inlet of the acidification tank;

the acid source can be fresh acid or acid liquor generated by the bipolar membrane device or the bipolar membrane device'; the purpose of adding acid is that if the aqueous solution entering the bipolar membrane device or the bipolar membrane device ' contains carbonate or bicarbonate, carbon dioxide gas can be generated in an acid chamber, an acid chamber I or an acid chamber II in the operation of the bipolar membrane device or the bipolar membrane device ', and the operation stability of the bipolar membrane device or the bipolar membrane device ' can be influenced.

The acid adding unit is used for adding acid, the purpose of adding acid is to neutralize a small amount of carbonate and bicarbonate radical remained in the water solution by acid, and the pH value is controlled to be 1-7 generally;

Based on the above water treatment system, preferably, the inlet of the acid adding unit is connected to an acid tank or an acid pipeline, an acid tank overflow port of the bipolar membrane device, an acid tank one overflow port, an acid tank two overflow port or an acid generating tank of the bipolar membrane device';

based on the above water treatment system, it is preferable to automatically monitor the pH of the aqueous solution after the addition of acid, and to control the amount of acid added in a chain manner.

Based on the above water treatment system, it is preferable that the acid adding unit is followed by a decarbonizing tower, or a decarbonizing tower and a cooler:

based on the above water treatment system, preferably, the decarbonizing tower is operated to spray the aqueous solution from top to bottom, and the compressed air is convected with the aqueous solution from bottom to top to blow out the free carbon dioxide in the aqueous solution into the air.

Based on the above water treatment system, it is preferable that the discharge port of the water inlet tank of the electrodialysis device (discharged low concentration aqueous solution), the discharge port of the water inlet tank of the bipolar membrane device (discharged low concentration aqueous solution), or the weak brine discharge port of the bipolar membrane device '(discharged low concentration aqueous solution) be directly discharged, connected to the water inlet of the concentration unit, or connected to the water inlet of the concentration unit'.

Based on above water treatment system, it is preferred, concentration unit or concentration unit ' contains conventional evaporation concentration equipment (for example evaporation tower), reverse osmosis concentration equipment (contain reverse osmosis membrane shell, reverse osmosis membrane, high-pressure pump etc.), electrodialysis concentration equipment ' (the utility model discloses electrodialysis equipment means has used the utility model the new electrodialysis equipment that various membrane stacks were founded, electrodialysis equipment ' is conventional electrodialysis equipment, and its membrane stack contains negative membrane piece, positive membrane piece, does not use the utility model the membrane stack).

Based on above water treatment system, preferably, be equipped with except that hardness device:

when the treated aqueous solution contains hardness, a hardness removing device is arranged at any position before the water inlet of the electrodialysis device, the bipolar membrane device 'or the concentration unit (referring to any position before the water inlet of the electrodialysis device, the bipolar membrane device' or the concentration unit in the sequence of the flow direction of the treated aqueous solution).

Based on the above water treatment system, preferably, the hardness removing device may be a resin column filled with a resin for removing calcium and magnesium ions in water.

Based on the above water treatment system, preferably, the resin for removing calcium and magnesium ions in water is subjected to salt regeneration or acid regeneration after being saturated.

Based on the technical scheme, preferably, the tail gas is the tail gas of a terephthalic acid production device; or the tail gas of the terephthalic acid production device is subjected to organic matter removal (such as an RTO incineration method, a catalytic oxidation method and the like).

Has the advantages that:

the utility model provides a novel dialysis membrane stack, this membrane stack have increased different kinds of functions, to the quality of water and the specific treatment purpose needs of specific treatment target aqueous solution, reach special effect through this neotype membrane stack, the process is most important the utility model discloses on the basis of current electrodialysis, bipolar membrane equipment effect, turn into more pure material aqueous solution with source aqueous solution to do benefit to the resourceful application of the aqueous solution that obtains.

For example, when the existing three-compartment bipolar membrane equipment is used for treating sodium sulfate and sodium chloride, a mixed acid product of a sodium hydroxide product and hydrochloric acid and sulfuric acid can be obtained, after the treatment of the membrane stack I-4, three products of the sodium hydroxide product, the hydrochloric acid product and the sulfuric acid product can be obtained, and the mixed acid product of hydrochloric acid and sulfuric acid belongs to hazardous waste, but the resource utilization or the takeout can be realized by respectively obtaining the hydrochloric acid product and the sulfuric acid product after the treatment of the membrane stack I-4, so that the enterprise benefit is greatly increased;

When the existing two-compartment bipolar membrane equipment is used for treating sodium sulfate and sodium chloride, a mixed acid product of hydrochloric acid and sulfuric acid can be obtained, after the treatment of the membrane stack II-4, two products of a hydrochloric acid product and a sulfuric acid product can be obtained, and the mixed acid product of hydrochloric acid and sulfuric acid belongs to hazardous waste, but the hydrochloric acid product and the sulfuric acid product which are respectively obtained after the treatment of the membrane stack II-4 can be recycled or sold, so that the enterprise benefit is increased greatly;

the existing electrodialysis equipment can obtain concentrated sodium sulfate and sodium chloride mixed solution products when processing sodium sulfate and sodium chloride, and after the membrane stack III-3 is processed by the utility model, two products of concentrated sodium sulfate products and concentrated sodium chloride products can be obtained, which belongs to dangerous waste for the concentrated sodium sulfate and sodium chloride mixed solution products, but the concentrated sodium sulfate products and the concentrated sodium chloride products can be respectively obtained after the membrane stack III-3 is processed by the utility model, so that the resource utilization or the takeout can be realized, and the enterprise benefit is greatly increased;

meanwhile, the cost of the nanofiltration membrane is lower than that of the positive membrane and the negative membrane, namely, if the positive membrane and the negative membrane are replaced by the nanofiltration membrane, the equipment cost is greatly reduced.

For example: the price of the currently marketed Yangmi or Yin diaphragm is about 800 to 1000 Yuan RMB/square meter; relatively low cost compared to nanofiltration membranes, e.g. Film ^TM Fortilife ^TM XC-N nanofiltration membrane 34 square meters, commercially available 7000 Yuan RMB, reduced to 200 Yuan RMB/square meters, and nanofiltration membrane FilmTec ^TM NF270-400/34i, nanofiltration membrane FilmTec ^TM NF90-400/34i is cheaper and has a conversion of less than 200 yuan per square meter.

And simultaneously, utilize the utility model discloses the water treatment system of constituteing uses electrodialysis equipment to reach concentrated purpose simultaneously and separates the purpose of target ion, and an equipment reaches 2 effects, and is simple and with low costs.

Drawings

FIG. I-1: the principle schematic diagram of treating an aqueous solution containing univalent cations, divalent cations and univalent anions by alternately combining a bipolar membrane, an anion membrane, a nanofiltration membrane, a bipolar membrane, an anion membrane and a nanofiltration membrane is arranged in a membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate;

FIGS. I-1-1: the principle schematic diagram of treating an aqueous solution containing univalent cations, divalent cations, univalent anions and divalent anions is arranged in a membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate and comprises a bipolar membrane, an anionic membrane, a nanofiltration membrane, a bipolar membrane, an anionic membrane and a nanofiltration membrane in an alternating combination manner;

FIG. I-2: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent anions and univalent anions by the alternate combination of the bipolar membrane, the nanofiltration membrane, the anode membrane, the bipolar membrane, the nanofiltration membrane and the anode membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIG. I-2-1: the membrane stack is arranged in the direction from the positive electrode plate of the electrode → the negative electrode plate of the electrode and comprises a bipolar membrane, a nanofiltration membrane, an anode membrane, the bipolar membrane, the nanofiltration membrane and the anode membrane which are alternately combined to process an aqueous solution containing univalent cations, divalent cations, univalent anions and divalent anions;

FIGS. I-3: the membrane stack is arranged in the direction from the positive electrode plate of the electrode → the direction from the negative electrode plate of the electrode and comprises a bipolar membrane, a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane which are alternately combined to process an aqueous solution containing univalent cations, divalent cations and univalent anions;

FIG. I-3-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent anions and univalent anions by the alternating combination of a bipolar membrane, a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIGS. I-3-2: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations, univalent anions and divalent anions by the alternating combination of the bipolar membrane, the first nanofiltration membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIGS. I-4: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent anions and univalent anions by the alternate combination of the bipolar membrane, the nanofiltration membrane, the negative membrane, the positive membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane is distributed in the membrane stack from the direction of the positive plate of the electrode → the direction of the negative plate of the electrode;

FIG. I-4-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations, univalent anions and divalent anions by the alternate combination of the bipolar membrane, the nanofiltration membrane, the negative membrane, the positive membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIGS. I-5: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations and univalent anions by the alternate combination of the bipolar membrane, the negative membrane, the positive membrane, the nanofiltration membrane, the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIG. I-5-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations, univalent anions and divalent anions by the alternate combination of the bipolar membrane, the negative membrane, the positive membrane, the nanofiltration membrane, the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIGS. I-6: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations and univalent anions by the alternating combination of a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane and a second nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIG. I-6-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent anions and univalent anions by the alternating combination of a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane and a second nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIGS. I-6-2: the principle schematic diagram of processing an aqueous solution containing univalent cations, divalent cations, univalent anions and divalent anions by the alternating combination of a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, an anion membrane, an anode membrane and a second nanofiltration membrane is distributed in the membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate;

FIG. II-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations and univalent anions by the alternate combination of the bipolar membrane, the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIG. II-1-1: the principle schematic diagram of processing the aqueous solution containing monovalent cation, divalent anion, monovalent anion and divalent cation by the alternate combination of the bipolar membrane, the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIG. II-2: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent anions and univalent anions by the alternating combination of a nanofiltration membrane, a bipolar membrane, a nanofiltration membrane and a bipolar membrane is distributed in the membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate;

FIG. II-2-1: the membrane stack is arranged in the direction from the positive electrode plate of the electrode → the direction from the negative electrode plate of the electrode and comprises a nanofiltration membrane, a bipolar membrane, a nanofiltration membrane and the bipolar membrane which are alternately combined, and the principle schematic diagram of treating the aqueous solution containing univalent cations, divalent anions, univalent anions and divalent cations is shown;

FIG. II-3: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations and monovalent anions by the alternate combination of a bipolar membrane, an anode membrane, a nanofiltration membrane, a bipolar membrane, an anode membrane and a nanofiltration membrane is arranged in the membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate;

FIG. II-3-1: the membrane stack is arranged in the direction from the positive electrode plate of the electrode → the direction from the negative electrode plate of the electrode and comprises a bipolar membrane, an anode membrane, a nanofiltration membrane, the bipolar membrane, the anode membrane and the nanofiltration membrane which are alternately combined to process an aqueous solution containing univalent cations, divalent anions, univalent anions and divalent cations;

FIGS. II-4: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent anions and univalent anions by the alternate combination of the negative membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIG. II-4-1: the membrane stack is arranged in the direction from the positive electrode plate of the electrode → the direction from the negative electrode plate of the electrode, and comprises an anion membrane, a bipolar membrane, a nanofiltration membrane, an anion membrane, a bipolar membrane and a nanofiltration membrane which are alternately combined to process an aqueous solution containing univalent cations, divalent anions or more, univalent anions or divalent cations or more;

FIG. III-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, univalent anions and anions which are more than or equal to divalent anions by the alternating combination of a nanofiltration membrane, an anode membrane, a nanofiltration membrane and an anode membrane is distributed in the membrane stack from the direction of an electrode positive plate → the direction of an electrode negative plate;

FIG. III-1-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, bivalent or more cations, univalent anions and bivalent or more anions by the alternating combination of the nanofiltration membrane, the anode membrane, the nanofiltration membrane and the anode membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIG. III-2: the principle schematic diagram of treating the aqueous solution containing monovalent cation, divalent cation and monovalent anion by the alternate combination of the negative membrane, the nanofiltration membrane, the negative membrane and the nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIG. III-2-1: the principle schematic diagram of processing the aqueous solution containing univalent cations, univalent anions, anions greater than or equal to divalent anions and cations by the alternate combination of the negative membrane, the nanofiltration membrane, the negative membrane and the nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate of the electrode;

FIGS. III-3: the principle schematic diagram of processing the aqueous solution containing univalent cations, divalent cations and univalent anions by the alternate combination of an anion membrane, an anode membrane, a nanofiltration membrane, an anion membrane, an anode membrane and a nanofiltration membrane is distributed in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIG. III-3-1: the membrane stack is arranged in the direction from the positive electrode plate of the electrode to the negative electrode plate of the electrode, and comprises an alternating combination of an anion membrane, an anode membrane, a nanofiltration membrane, an anion membrane, an anode membrane and a nanofiltration membrane, and the principle schematic diagram of treating the aqueous solution containing univalent cations, univalent anions and bivalent anions not less than the univalent anions is shown;

FIG. III-3-2: the membrane stack is arranged in the direction from the positive electrode plate of the electrode → the negative electrode plate of the electrode and comprises an anion membrane, an anode membrane, a nanofiltration membrane, an anion membrane, an anode membrane and a nanofiltration membrane which are alternately combined to process an aqueous solution containing univalent cations, univalent anions, bivalent anions or more and bivalent cations;

FIGS. III-4: the principle schematic diagram of processing the aqueous solution containing univalent cations, bivalent or more cations, univalent anions and bivalent or more anions by the combination of an anion membrane, an anode membrane, a first nanofiltration membrane, a second nanofiltration membrane, an anion membrane, an anode membrane, a first nanofiltration membrane and a second nanofiltration membrane is arranged in the membrane stack from the direction of the positive electrode plate → the direction of the negative electrode plate;

FIG. IV-1: schematic diagrams of the water inlet tank and the water inlet chamber;

FIG. IV-2: schematic diagram of the concentration tank and the concentration chamber;

FIG. IV-3: a schematic diagram of a first concentration tank and a first concentration chamber;

FIG. IV-4: a schematic diagram of a second concentration tank and a second concentration chamber;

FIG. IV-5: a third concentrating tank and a third concentrating chamber;

FIGS. IV-6: schematic diagram of acid tank and acid chamber;

FIGS. IV-7: a schematic diagram of an acid tank I and an acid chamber I;

FIGS. IV-8: a schematic diagram of the acid tank II and the acid chamber II;

FIGS. IV-9: schematic diagram of alkali tank and alkali chamber;

FIGS. IV-10: a first alkali tank and a first alkali chamber;

FIG. IV-11: a second alkali tank and a second alkali chamber;

FIG. IV-12: schematic diagrams of a polar water tank I and a polar water chamber I;

FIGS. IV-13: a schematic diagram of a polar water tank II and a polar water chamber II;

FIG. IV-14: schematic diagrams of a polar water tank, a polar water chamber I and a polar water chamber II;

FIG. V-1: example I-1 schematic representation of a membrane stack;

FIG. V-2: example I-2 schematic representation of a membrane stack;

FIG. V-3: example I-3 schematic representation of a membrane stack;

FIG. V-4: example I-4 schematic of a membrane stack;

FIG. V-5: example I-5 schematic of a membrane stack;

FIG. V-6: examples I-6 schematic representation of the membrane stack;

FIG. V-7: example II-1 schematic of a membrane stack;

FIG. V-8: example II-2 schematic representation of a membrane stack;

FIG. V-9: example II-3 schematic representation of a membrane stack;

FIG. V-10: examples II-4 schematic diagrams of membrane stacks;

FIG. V-11: example III-1 schematic representation of a membrane stack;

FIG. V-12: example III-2 schematic representation of a membrane stack;

FIG. V-13: example III-3 schematic representation of a membrane stack;

FIG. V-14: example iii-4 schematic representation of a membrane stack.

FIG. VI: membrane stack and tank and pump combination schematic, wherein: the membrane stack needs to provide several sets of different tanks, pumps and different chambers in the membrane stack to form a circulation to operate according to the types of the chambers in the membrane stack, and the figure only shows a schematic circulation composition diagram of one set of tank, pump and corresponding chambers, that is, the tank, pump and corresponding chambers can be: the water inlet tank and the water inlet circulating pump correspond to the water inlet chamber of the membrane stack; the concentration tank and the concentration circulating pump correspond to the concentration chamber of the membrane stack; the first concentration tank and the first concentration circulating pump correspond to the first concentration chamber of the membrane stack; the concentration tank II and the concentration circulating pump II correspond to the concentration chamber II of the membrane stack; the concentration tank III and the concentration circulating pump III correspond to a concentration chamber III of the membrane stack; the acid tank and the acid circulating pump correspond to the acid chamber of the membrane stack; the acid tank I and the acid circulating pump correspond to the acid chamber I of the membrane stack; the acid tank II and the acid circulating pump II correspond to the acid chamber II of the membrane stack; the alkali tank and the alkali circulating pump correspond to the alkali chamber of the membrane stack; the first alkali tank and the first alkali circulating pump correspond to the first alkali chamber of the membrane stack; the second alkali tank and the second alkali chamber of the corresponding membrane stack of the alkali circulating pump are arranged; the polar water tank I and the polar water pump I correspond to a polar water chamber I of the membrane stack; the polar water tank II and the polar water pump II correspond to a polar water chamber II of the membrane stack; or the polar water tank and the polar water pump correspond to the polar water chamber I and the polar water chamber II of the membrane stack;

FIG. VII: example VII A schematic view of a water treatment system;

FIG. VIII: example viii schematic of a water treatment system.

Legend:

Detailed Description

The following non-limiting examples will allow one of ordinary skill in the art to more fully understand the present invention without limiting it in any way.

The bipolar membrane used in the following embodiments of the present invention is Hangzhou blue technologySingle sheet 1m supplied by Co., ltd ² A bipolar membrane; the sun sheet is 1m single sheet provided by Hangzhou blue technology corporation ² A male diaphragm; the negative diaphragm is a single 1m diaphragm provided by Hangzhou blue technology corporation ² A negative diaphragm; the partition board between the diaphragms is provided by Hangzhou blue technology GmbH; the nanofiltration membrane is Film ^TM Fortilife ^TM An XC-N nanofiltration membrane is disassembled and paved into a flat plate for use; the positive electrode plate and the negative electrode plate are provided by Hangzhou blue technology corporation; the electrodialysis equipment is EX-4S-ED provided by Hangzhou blue technology GmbH, and the bipolar membrane equipment is EX-4S provided by Hangzhou blue technology GmbH.

Examples I to 1

As shown in fig. v-1, fig. iv-6, fig. iv-9, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a bipolar membrane 21, a cathode membrane 11, and a nanofiltration membrane 3, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrometer control system, a pump, a tank, and the like.

The arrangement mode is that an electrode positive plate 33, a negative membrane 11, a

nanofiltration membrane

3, 10 repeated combinations of a bipolar membrane 21, the negative membrane 11 and the nanofiltration membrane 3, the bipolar membrane 21, the negative membrane 11 and an electrode negative plate 34 are arranged in sequence, and two sides of each membrane are respectively provided with a partition board 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the negative membrane 11, a water inlet chamber 5 is formed between the negative membrane 11 and the nanofiltration membrane 3, an alkali chamber 24 is formed between the nanofiltration membrane 3 and the bipolar membrane 21, and an acid chamber 25 is formed between the bipolar membrane 21 and the negative membrane 11, so that the electrode water chamber II 89 is formed between the last negative membrane 11 and the electrode negative plate 34 repeatedly.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the acid chamber 25, the outlet of the acid chamber 25 is connected to the inlet of the acid tank 54, the outlet of the acid tank 54 is connected to the acid circulating pump 55, the outlet of the acid circulating pump 55 is connected to the inlet of the acid chamber 25 to form a circulation, and the acid tank 54 is further provided with a water inlet pipe 77 and an overflow port 78; for the alkali chamber 24, the outlet of the alkali chamber 24 is connected to the inlet of an alkali tank 60, the outlet of the alkali tank 60 is connected to an alkali circulating pump 61, the outlet of the alkali circulating pump 61 is connected to the inlet of the alkali chamber 24 to form a circulation, and the alkali tank 60 is further provided with a water inlet pipe 83 and an overflow port 84; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; pure water enters the acid tank 54 from a water inlet pipe 77 of the acid tank 54, and the solution in the acid tank 54 returns to the acid tank 54 through the acid circulating pump 55 and the acid chamber 25 to form circulation and is discharged from an overflow port 78 in an overflow way; the pure water enters the alkali tank 60 from the water inlet pipe 83 of the alkali tank 60, and the solution in the alkali tank 60 returns to the alkali tank 60 through the alkali circulating pump 61 and the alkali chamber 24 to form circulation and is discharged from the overflow port 84 in an overflowing manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. I-1 and FIG. I-1 )

1mol/L hydrochloric acid is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; pure water is supplied from a water inlet pipe 77 of the acid tank 54, and the acid circulating pump 55 is started to circulate; supplying pure water from the water inlet pipe 83 of the alkali tank 60, and starting the alkali circulating pump 61 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V.

Experiment 1: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, divalent cations and univalent anions, pure water is used for preparing an aqueous solution containing 2% of sodium chloride and 2% of barium chloride, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44, so that the salt concentration = 0.2-0.25 mol/L equivalent (converted into univalent ions) in the water inlet tank 42 is ensured.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1.5-2 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.7mol/L, sodium ion is 3.9 percent, barium ion can not be detected, and chloride ion is 27ppm, and is alkali corresponding to univalent cation;

the hydrogen ion concentration of the acid tank 54 is detected to control the flow of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.2-1.5 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the hydrogen ion concentration was 1.4mol/L, sodium ion concentration was 103ppm, barium ion concentration was 25ppm, and chloride ion concentration was 4.9%, and the acid corresponded to monovalent anion.

Experiment 2: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, divalent anions and univalent anions, pure water is used for preparing an aqueous solution containing 2% of sodium chloride and 2% of sodium sulfate, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44, so that the salt concentration = 0.2-0.25 mol/L equivalent (converted into univalent ions) in the water inlet tank 42 is ensured.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.2mol/L, the concentration of sodium ion is 2.7 percent, sulfate radical can not be detected, and chloride ion is 34ppm, which is alkali corresponding to univalent cation;

the hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.5-1.8 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions is 1.6mol/L, the concentration of sodium ions is 25ppm, the concentration of sulfate radicals is 4 percent, and the concentration of chloride ions is 2.7 percent, and the hydrogen ions are monovalent anions and acids corresponding to anions not less than divalent anions.

Experiment 3: aqueous solution to be treated: contains univalent positive ions and univalent negative ions, sodium chloride with the concentration of 4 percent is prepared by pure water and is supplemented into a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44 so as to ensure that the salt concentration in the water inlet tank 42 is = 0.2-0.25 mol/L equivalent (converted into univalent ions).

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1.2-1.6 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.5mol/L, sodium ion is 3.5%, and chloride ion is 68ppm, which is alkali corresponding to univalent cation;

The hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.5-2 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: hydrogen ion concentration 1.9mol/L, sodium ion 46ppm, chloride ion 6.7% ppm, is monovalent anion corresponding acid.

Examples I to 2

As shown in fig. v-2, fig. iv-1, fig. iv-6, fig. iv-9, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a bipolar membrane 21, a nanofiltration membrane 3, and an anode membrane 4, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electricity meter control system, a pump, a tank, and the like.

The arrangement mode is that an electrode positive plate 33, an

anode membrane

4, 10 repeated bipolar membrane 21, a nanofiltration membrane 3, an anode membrane 4 combination and an electrode negative plate 34 are arranged in sequence, and separators 37 are arranged on two sides of each membrane.

The film stack forming equipment is utilized: according to the sequence of the direction of the electrode positive plate 33 → the direction of the electrode negative plate 34, a polar water chamber I68 is formed between the electrode positive plate 33 and the anode membrane 4, an alkali chamber 24 is formed between the anode membrane 4 and the bipolar membrane 21, an acid chamber 25 is formed between the bipolar membrane 21 and the nanofiltration membrane 3, and a water inlet chamber 5 is formed between the nanofiltration membrane 3 and the anode membrane 4, so that a polar water chamber II 89 is formed between the last anode membrane 4 and the electrode negative plate 34 repeatedly.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; pure water enters the acid tank 54 from a water inlet pipe 77 of the acid tank 54, and the solution in the acid tank 54 returns to the acid tank 54 through the acid circulating pump 55 and the acid chamber 25 to form circulation and is discharged from an overflow port 78 in an overflow way; the pure water enters the alkali tank 60 from the water inlet pipe 83 of the alkali tank 60, and the solution in the alkali tank 60 returns to the alkali tank 60 through the alkali circulating pump 61 and the alkali chamber 24 to form circulation and is discharged from the overflow port 84 in an overflowing manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water tank II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. I-2 and FIG. I-2-1 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; pure water is supplied from a water inlet pipe 77 of the acid tank 54, and the acid circulating pump 55 is started to circulate; supplying pure water from the water inlet pipe 83 of the alkali tank 60, and starting the alkali circulating pump 61 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.2mol/L, sodium ion is 1.3%, barium ion is 4.2%, and chloride ion is 55ppm, and the hydroxide radical is univalent cation and alkali corresponding to the bivalent cation;

the hydrogen ion concentration of the acid tank 54 is detected to control the flow of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.2-1.7 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.5mol/L, sodium ions were 36ppm, barium ions were not detected, and chloride ions were 5.3%, which is an acid corresponding to a monovalent anion.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.2mol/L, the concentration of sodium ion is 2.7%, the concentration of sulfate radical is 26ppm, the concentration of chloride ion is 22ppm, and the hydroxide radical is alkali corresponding to univalent cation;

the hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.5-2 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.6mol/L, sodium ions were 43ppm, sulfate groups were not detected, and chloride ions were 5.5% and were acids corresponding to monovalent anions.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1.3-1.7 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.5mol/L, sodium ion is 3.5%, and chloride ion is 57ppm, which is alkali corresponding to univalent cation;

The hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.5-2 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the hydrogen ion concentration was 1.6mol/L, sodium ion concentration was 24ppm, and chloride ion concentration was 5.7%, and the acid corresponded to a monovalent anion.

Examples I to 3

As shown in fig. v-3, fig. iv-1, fig. iv-6, fig. iv-9, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a bipolar membrane 21, a first nanofiltration membrane 15, and a second nanofiltration membrane 16, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electricity meter control system, a pump, a tank, and the like.

The arrangement mode comprises an electrode positive plate 33, a

second nanofiltration membrane

16, 10 repeated combinations of a bipolar membrane 21, a first nanofiltration membrane 15 and a second nanofiltration membrane 16 and an electrode negative plate 34 in sequence, and the two sides of each membrane are respectively provided with a partition board 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the second nanofiltration membrane 16, an alkali chamber 24 is formed between the second nanofiltration membrane 16 and the bipolar membrane 21, an acid chamber 25 is formed between the bipolar membrane 21 and the first nanofiltration membrane 15, and a water inlet chamber 5 is formed between the first nanofiltration membrane 15 and the second nanofiltration membrane 16, so that the steps are repeated, and an electrode water chamber II 89 is formed between the last second nanofiltration membrane 16 and the electrode negative plate 34.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; pure water enters the acid tank 54 from a water inlet pipe 77 of the acid tank 54, and the solution in the acid tank 54 returns to the acid tank 54 through the acid circulating pump 55 and the acid chamber 25 to form circulation and is discharged from an overflow port 78 in an overflowing manner; the pure water enters the alkali tank 60 from the water inlet pipe 83 of the alkali tank 60, and the solution in the alkali tank 60 returns to the alkali tank 60 through the alkali circulating pump 61 and the alkali chamber 24 to form circulation and is discharged from the overflow port 84 in an overflowing manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water tank II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. I-3, FIG. I-3-1, and FIG. I-3-2 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; pure water is supplied from a water inlet pipe 77 of the acid tank 54, and the acid circulating pump 55 is started to circulate; supplying pure water from the water inlet pipe 83 of the alkali tank 60, and starting the alkali circulating pump 61 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.2mol/L, the concentration of sodium ion is 2.8 percent, barium ion cannot be detected, and chloride ion is 74ppm, and is alkali corresponding to univalent cation;

the hydrogen ion concentration of the acid tank 54 is detected to control the flow of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.3-1.7 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.5mol/L, sodium ions were 48ppm, barium ions were not detected, and chloride ions were 5.2%, which is an acid corresponding to a monovalent anion.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.3mol/L, the concentration of sodium ion is 2.9 percent, sulfate radical can not be detected, and chloride ion is 32ppm, and is alkali corresponding to univalent cation;

the hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.5-2 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.6mol/L, sodium ions were 38ppm, sulfate groups were not detected, and chloride ions were 5.5% and were acids corresponding to monovalent anions.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.3mol/L, sodium ion is 3%, and chloride ion is 52ppm, which is alkali corresponding to univalent cation;

The hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.2-1.5 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the hydrogen ion concentration was 1.3mol/L, sodium ion concentration was 65ppm, and chloride ion concentration was 4.7%, and the acid corresponded to the monovalent anion.

Examples I to 4

As shown in fig. v-4, fig. iv-1, fig. iv-7, fig. iv-8, fig. iv-9, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a bipolar membrane 21, a nanofiltration membrane 3, a negative membrane 11, and a positive membrane 4, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrometer control system, a pump, a tank, and the like.

The arrangement mode is that an electrode positive plate 33, an

anode membrane

4, 10 repeated bipolar membranes 21, a nanofiltration membrane 3, a cathode membrane 11, an anode membrane 4 and an electrode negative plate 34 are arranged in sequence, and separators 37 are arranged on two sides of each membrane.

The film stack forming equipment is utilized: according to the sequence of the direction of the electrode positive plate 33 → the direction of the electrode negative plate 34, an electrode water chamber I68 is formed between the electrode positive plate 33 and the anode membrane 4, an alkali chamber 24 is formed between the anode membrane 4 and the bipolar membrane 21, an acid chamber I28 is formed between the bipolar membrane 21 and the nanofiltration membrane 3, an acid chamber II 29 is formed between the nanofiltration membrane 3 and the cathode membrane 11, a water inlet chamber 5 is formed between the cathode membrane 11 and the anode membrane 4, and accordingly, the last anode membrane 4 and the electrode negative plate 34 are repeated to form an electrode water chamber II 89.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the acid chamber I28, the outlet of the acid chamber I28 is connected to the inlet of the acid tank I56, the outlet of the acid tank I56 is connected to the acid circulating pump I57, the outlet of the acid circulating pump I57 is connected to the inlet of the acid chamber I28 to form a circulation, and the acid tank I56 is further provided with a water inlet pipe 79 and an overflow port 80; for the second acid chamber 29, the outlet of the second acid chamber 29 is connected to the inlet of the second acid tank 58, the outlet of the second acid tank 58 is connected to the second acid circulating pump 59, the outlet of the second acid circulating pump 59 is connected to the inlet of the second acid chamber 29 to form a circulation, and the second acid tank 58 is further provided with a water inlet pipe 81 and an overflow port 82; for the alkali chamber 24, the outlet of the alkali chamber 24 is connected to the inlet of an alkali tank 60, the outlet of the alkali tank 60 is connected to an alkali circulating pump 61, the outlet of the alkali circulating pump 61 is connected to the inlet of the alkali chamber 24 to form a circulation, and the alkali tank 60 is further provided with a water inlet pipe 83 and an overflow port 84; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; pure water enters the first acid tank 56 from a water inlet pipe 79 of the first acid tank 56, and the solution in the first acid tank 56 returns to the first acid tank 56 through a first acid circulating pump 57 and a first acid chamber 28 to form circulation and is discharged from an overflow port 80 in an overflow manner; the pure water enters the second acid tank 58 from the water inlet pipe 81 of the second acid tank 58, and the solution in the second acid tank 58 returns to the second acid tank 58 through the second acid circulating pump 59 and the second acid chamber 29 to form circulation and is discharged from the overflow port 82 in an overflow manner; the pure water enters the alkali tank 60 from the water inlet pipe 83 of the alkali tank 60, and the solution in the alkali tank 60 returns to the alkali tank 60 through the alkali circulating pump 61 and the alkali chamber 24 to form circulation and is discharged from the overflow port 84 in an overflowing manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. I-4 and FIG. I-4-1 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; supplying pure water from a water inlet pipe 79 of the first acid tank 56, and starting a first acid circulating pump 57 for circulation; supplying pure water from a water inlet pipe 81 of the second acid tank 58, and starting a second acid circulating pump 59 for circulation; supplying pure water from the water inlet pipe 83 of the alkali tank 60, and starting the alkali circulating pump 61 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

Experiment 1: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, divalent anions and univalent anions, pure water is used for preparing an aqueous solution containing 2% of sodium chloride and 2% of sodium sulfate, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44, so that the salt concentration = 0.2-0.25 mol/L equivalent (converted into univalent ions) in the water inlet tank 42 is ensured.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.3mol/L, the concentration of sodium ion is 2.9%, the concentration of sulfate radical is 25ppm, the concentration of chloride ion is 32ppm, and the hydroxide radical is alkali corresponding to univalent cation;

the hydrogen ion concentration of the first acid tank 56 is detected to control the flow of the water inlet pipe 79, so as to ensure that the hydrogen ion concentration of the first acid tank 56 is = 1.5-2 mol/L, and the product obtained by overflowing the first acid tank 56 from the overflow port 80 is analyzed as follows: the concentration of hydrogen ions is 1.6mol/L, the concentration of sodium ions is 6ppm, sulfate radicals cannot be detected, and chloride ions are 5.4 percent and are acids corresponding to univalent anions;

the hydrogen ion concentration of the second acid tank 58 is detected to control the flow of the water inlet pipe 81, so as to ensure that the hydrogen ion concentration of the second acid tank 58 is = 1-1.5 mol/L, and the product obtained by overflowing the second acid tank 58 from the overflow port 82 is analyzed as follows: the concentration of hydrogen ions is 1.3mol/L, the concentration of sodium ions is 65ppm, the concentration of sulfate radicals is 5.4 percent, the concentration of chloride ions is 0.8 percent, the acid corresponding to divalent anions is mainly formed, and the acid corresponding to a small amount of monovalent anions is also contained.

Examples I to 5

As shown in fig. v-5, fig. iv-1, fig. iv-6, fig. iv-10, fig. iv-11, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack and accessory equipment, the membrane stack mainly includes a bipolar membrane 21, a negative membrane 11, a positive membrane 4, and a nanofiltration membrane 3, the accessory equipment mainly includes an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member is used for clamping the membranes), a sealing member (in all embodiments, the sealing member is used for sealing each chamber formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrometer control system, a pump, a tank, and the like.

The membrane is sequentially arranged in a mode of combining an electrode positive plate 33, an anode membrane 4, a

nanofiltration membrane

3, 10 repeated bipolar membranes 21, a cathode membrane 11, an anode membrane 4 and a nanofiltration membrane 3, a bipolar membrane 21, a cathode membrane 11, an anode membrane 4 and an electrode negative plate 34, and the two sides of each membrane are respectively provided with a partition plate 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the anode membrane 4, an alkali chamber I26 is formed between the anode membrane 4 and the nanofiltration membrane 3, an alkali chamber II 27 is formed between the nanofiltration membrane 3 and the bipolar membrane 21, an acid chamber 25 is formed between the bipolar membrane 21 and the cathode membrane 11, a water inlet chamber 5 is formed between the cathode membrane 11 and the anode membrane 4, and accordingly, a water chamber II 89 is formed between the last anode membrane 4 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the acid chamber 25, the outlet of the acid chamber 25 is connected to the inlet of the acid tank 54, the outlet of the acid tank 54 is connected to the acid circulating pump 55, the outlet of the acid circulating pump 55 is connected to the inlet of the acid chamber 25 to form a circulation, and the acid tank 54 is further provided with a water inlet pipe 77 and an overflow port 78; for the first alkali chamber 26, the outlet of the first alkali chamber 26 is connected to the inlet of the first alkali tank 62, the outlet of the first alkali tank 62 is connected to the first alkali circulating pump 63, the outlet of the first alkali circulating pump 63 is connected to the inlet of the first alkali chamber 26 to form a circulation, and the first alkali tank 62 is further provided with a water inlet pipe 85 and an overflow port 86; for the second alkali chamber 27, the outlet of the second alkali chamber 27 is connected to the inlet of the second alkali tank 64, the outlet of the second alkali tank 64 is connected to the second alkali circulating pump 65, the outlet of the second alkali circulating pump 65 is connected to the inlet of the second alkali chamber 27 to form a circulation, and the second alkali tank 64 is further provided with a water inlet pipe 87 and an overflow port 88; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; pure water enters the acid tank 54 from a water inlet pipe 77 of the acid tank 54, and the solution in the acid tank 54 returns to the acid tank 54 through the acid circulating pump 55 and the acid chamber 25 to form circulation and is discharged from an overflow port 78 in an overflow way; the pure water enters the first alkali tank 62 from the water inlet pipe 85 of the first alkali tank 62, and the solution in the first alkali tank 62 returns to the first alkali tank 62 through the first alkali circulating pump 63 and the first alkali chamber 26 to form circulation and is discharged from the overflow port 86 in an overflow manner; the pure water enters the second alkali tank 64 from the water inlet pipe 87 of the second alkali tank 64, and the solution in the second alkali tank 64 returns to the second alkali tank 64 through the second alkali circulating pump 65 and the second alkali chamber 27 to form circulation and is discharged from the overflow port 88 in an overflow manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. I-5 and FIG. I-5-1 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; pure water is supplied from a water inlet pipe 77 of the acid tank 54, and the acid circulating pump 55 is started to circulate; supplying pure water from a water inlet pipe 85 of the first alkali tank 62, and circulating by using a first alkali circulating pump 63; pure water is supplemented from a water inlet pipe 87 of the second alkali tank 64, and the second alkali circulating pump 65 circulates; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V.

Experiment 1: aqueous solution to be treated: the water-soluble salt-free water-saving agent comprises univalent cations, divalent cations and univalent anions, pure water is prepared into an aqueous solution containing 2% of sodium chloride and 2% of barium chloride, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44 so as to ensure that the salt concentration = 0.2-0.25 mol/L equivalent (converted into univalent ions) concentration in the water inlet tank 42.

And (4) conclusion: the flow of the water inlet pipe 85 is controlled by detecting the hydroxyl concentration of the first alkali tank 62 to ensure that the hydroxyl concentration of the first alkali tank 62 = 0.7-1 mol/L, and the product obtained by overflowing the first alkali tank 62 from the overflow port 86 is analyzed as follows: 0.9mol/L hydroxide ion concentration, 4489ppm sodium ion, 5.2% barium ion, 45ppm chloride ion, mainly including a base corresponding to the formation of divalent cations or more, and also including a base corresponding to low-concentration monovalent cations;

the flow of the water inlet pipe 87 is controlled by detecting the hydroxide concentration of the second alkali tank 64 to ensure that the hydroxide concentration of the second alkali tank 64 is = 1-1.5 mol/L, and the product obtained by overflowing the second alkali tank 64 from the overflow port 88 is analyzed as follows: the concentration of hydroxide radical is 1.2mol/L, the concentration of sodium ion is 2.6 percent, barium ion cannot be detected, and chloride ion is 7ppm, and is alkali corresponding to univalent cation;

The hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.3-1.7 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.5mol/L, sodium ions were 65ppm, barium ions were not detected, and chloride ions were 5.3%, which is an acid corresponding to a monovalent anion.

Examples I to 6

As shown in fig. v-6, fig. iv-1, fig. iv-7, fig. iv-8, fig. iv-10, fig. iv-11, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly comprises a membrane stack and accessory equipment, wherein the membrane stack mainly comprises a bipolar membrane 21, a first nanofiltration membrane 15, a negative membrane 11, a positive membrane 4, and a second nanofiltration membrane 16, and the accessory equipment mainly comprises an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member is used for clamping the membranes), a sealing member (in all embodiments, the sealing member is used for sealing each chamber formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrical instrument control system, a pump, a tank, and the like.

The membrane is sequentially composed of an electrode positive plate 33, an anode membrane 4, a

second nanofiltration membrane

16, 10 repeated bipolar membranes 21, a first nanofiltration membrane 15, a cathode membrane 11, the anode membrane 4 and the second nanofiltration membrane 16, the bipolar membranes 21, the first nanofiltration membrane 15, the cathode membrane 11, the anode membrane 4 and an electrode negative plate 34, and the two sides of each membrane are provided with a partition plate 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the positive membrane 4, an alkali chamber I26 is formed between the positive membrane 4 and the second nanofiltration membrane 16, an alkali chamber II 27 is formed between the second nanofiltration membrane 16 and the bipolar membrane 21, an acid chamber II 29 is formed between the bipolar membrane 21 and the first nanofiltration membrane 15, an acid chamber I28 is formed between the first nanofiltration membrane 15 and the negative membrane 11, and a water inlet chamber 5 is formed between the negative membrane 11 and the positive membrane 4, so that a electrode water chamber II 89 is formed between the last positive membrane 4 and the electrode negative plate 34 repeatedly.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the acid chamber I28, the outlet of the acid chamber I28 is connected to the inlet of the acid tank I56, the outlet of the acid tank I56 is connected to the acid circulating pump I57, the outlet of the acid circulating pump I57 is connected to the inlet of the acid chamber I28 to form a circulation, and the acid tank I56 is further provided with a water inlet pipe 79 and an overflow port 80; for the second acid chamber 29, the outlet of the second acid chamber 29 is connected to the inlet of the second acid tank 58, the outlet of the second acid tank 58 is connected to the second acid circulating pump 59, the outlet of the second acid circulating pump 59 is connected to the inlet of the second acid chamber 29 to form a circulation, and the second acid tank 58 is further provided with a water inlet pipe 81 and an overflow port 82; for the first alkali chamber 26, the outlet of the first alkali chamber 26 is connected to the inlet of the first alkali tank 62, the outlet of the first alkali tank 62 is connected to the first alkali circulating pump 63, the outlet of the first alkali circulating pump 63 is connected to the inlet of the first alkali chamber 26 to form a circulation, and the first alkali tank 62 is further provided with a water inlet pipe 85 and an overflow port 86; for the second alkali chamber 27, the outlet of the second alkali chamber 27 is connected to the inlet of the second alkali tank 64, the outlet of the second alkali tank 64 is connected to the second alkali circulating pump 65, the outlet of the second alkali circulating pump 65 is connected to the inlet of the second alkali chamber 27 to form a circulation, and the second alkali tank 64 is further provided with a water inlet pipe 87 and an overflow port 88; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 passes through the water inlet circulating pump 43 and the water inlet chamber 5 and returns to the water inlet tank 42 to form circulation, and the water solution overflows from the overflow port 45 and is discharged; pure water enters the first acid tank 56 from a water inlet pipe 79 of the first acid tank 56, and the solution in the first acid tank 56 passes through the first acid circulating pump 57 and the first acid chamber 28 and then returns to the first acid tank 56 to form a circulation, and is overflowed and discharged from an overflow port 80; pure water enters the second acid tank 58 from a water inlet pipe 81 of the second acid tank 58, and the solution in the second acid tank 58 returns to the second acid tank 58 through a second acid circulating pump 59 and a second acid chamber 29 to form circulation and is discharged from an overflow port 82 in an overflowing manner; the pure water enters the first alkali tank 62 from a water inlet pipe 85 of the first alkali tank 62, and the solution in the first alkali tank 62 returns to the first alkali tank 62 through a first alkali circulating pump 63 and a first alkali chamber 26 to form circulation and is discharged from an overflow port 86 in an overflowing manner; the pure water enters the second alkali tank 64 from the water inlet pipe 87 of the second alkali tank 64, the solution in the second alkali tank 64 passes through the second alkali circulating pump 65 and the second alkali chamber 27 and then returns to the second alkali tank 64 to form circulation, and the circulation is overflowed and discharged from the overflow port 88; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. I-6, FIG. I-6-1, and FIG. I-6-2 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; supplying pure water from a water inlet pipe 79 of the first acid tank 56, and starting a first acid circulating pump 57 for circulation; supplying pure water from a water inlet pipe 81 of the second acid tank 58, and starting a second acid circulating pump 59 for circulation; supplying pure water from a water inlet pipe 85 of the first alkali tank 62, and circulating by using a first alkali circulating pump 63; pure water is supplemented from a water inlet pipe 87 of the second alkali tank 64, and the second alkali circulating pump 65 circulates; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V.

And (4) conclusion: the flow of the water inlet pipe 85 is controlled by detecting the hydroxyl concentration of the first alkali tank 62 to ensure that the hydroxyl concentration of the first alkali tank 62 is = 0.8-1.2 mol/L, and the product obtained by overflowing the first alkali tank 62 from the overflow port 86 is analyzed as follows: the concentration of hydroxide radical is 1mol/L, the concentration of sodium ion 4779ppm, the concentration of barium ion 5.1 percent and the concentration of chloride ion 56ppm are mainly alkali corresponding to the formation of divalent cation, and the alkali also contains alkali corresponding to low-concentration monovalent cation;

The flow of the water inlet pipe 87 is controlled by detecting the hydroxide concentration of the second alkali tank 64 to ensure that the hydroxide concentration of the second alkali tank 64 is = 1.3-1.7 mol/L, and the product obtained by overflowing the second alkali tank 64 from the overflow port 88 is analyzed as follows: the concentration of hydroxide radical is 1.5mol/L, sodium ion is 3.5%, barium ion cannot be detected, and chloride ion is 5ppm, and is alkali corresponding to univalent cation;

the hydrogen ion concentration of the first acid tank 56 is detected to control the flow of the water inlet pipe 79, so as to ensure that the hydrogen ion concentration of the first acid tank 56 is = 1.5-2 mol/L, and the product obtained by overflowing the first acid tank 56 from the overflow port 80 is analyzed as follows: the concentration of hydrogen ions is 1.8mol/L, the concentration of sodium ions is 39ppm, the concentration of barium ions is 22ppm, and the concentration of chloride ions is 6.3 percent, and the hydrogen ions are acids corresponding to univalent anions;

the hydrogen ion concentration of the second acid tank 58 is detected to control the flow rate of the water inlet pipe 81, so as to ensure that the hydrogen ion concentration of the second acid tank 58 is = 1-1.5 mol/L, and the product obtained by overflowing the second acid tank 58 from the overflow port 82 is analyzed as follows: the concentration of hydrogen ions was 1.4mol/L, sodium ions were 8ppm, barium ions were not detected, and chloride ions were 5% and were acids corresponding to monovalent anions.

And (4) conclusion: the flow of the water inlet pipe 85 is controlled by detecting the hydroxyl concentration of the first alkali tank 62 to ensure that the hydroxyl concentration of the first alkali tank 62 is = 1-1.5 mol/L, and the product obtained by overflowing the first alkali tank 62 from the overflow port 86 is analyzed as follows: the concentration of hydroxide radical is 1.3mol/L, the concentration of sodium ion is 2.9%, the concentration of sulfate radical is 33ppm, the concentration of chloride ion is 19ppm, and the hydroxide radical is alkali corresponding to univalent cation;

the flow of the water inlet pipe 87 is controlled by detecting the hydroxide concentration of the second alkali tank 64 to ensure that the hydroxide concentration of the second alkali tank 64 = 0.8-1.2 mol/L, and the product obtained by overflowing the second alkali tank 64 from the overflow port 88 is analyzed as follows: the concentration of hydroxide radical is 1mol/L, the concentration of sodium ion is 2.3 percent, sulfate radical can not be detected, and chloride ion is 7ppm, and is alkali corresponding to univalent cation;

the hydrogen ion concentration of the first acid tank 56 is detected to control the flow of the water inlet pipe 79, so as to ensure that the hydrogen ion concentration of the first acid tank 56 is = 1-1.5 mol/L, and the product obtained by overflowing the first acid tank 56 from the overflow port 80 is analyzed as follows: the concentration of hydrogen ions is 1.4mol/L, the concentration of sodium ions is 46ppm, the concentration of sulfate radicals is 5.6 percent, the concentration of chloride ions is 0.7 percent, the acid corresponding to divalent anions is mainly used, and the acid corresponding to a small amount of monovalent anions is also contained;

the hydrogen ion concentration of the second acid tank 58 is detected to control the flow of the water inlet pipe 81, so as to ensure that the hydrogen ion concentration of the second acid tank 58 is = 1.5-2 mol/L, and the product obtained by overflowing the second acid tank 58 from the overflow port 82 is analyzed as follows: the concentration of hydrogen ions was 1.6mol/L, sodium ions were 21ppm, sulfate groups were not detected, and chloride ions were 5.6% and were acids corresponding to monovalent anions.

Example II-1

As shown in fig. v-7, fig. iv-1, fig. iv-9, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a bipolar membrane 21 and a nanofiltration membrane 3, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electricity meter control system, a pump, a tank, and the like.

The arrangement mode is that an electrode positive plate 33, a

nanofiltration membrane

3, 10 repeated combinations of a bipolar membrane 21 and a nanofiltration membrane 3 and an electrode negative plate 34 are arranged in sequence, and two sides of each membrane are provided with a partition plate 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the nanofiltration membrane 3, an alkali chamber 24 is formed between the nanofiltration membrane 3 and the bipolar membrane 21, and a water inlet chamber 5 is formed between the bipolar membrane 21 and the nanofiltration membrane 3, so that a water chamber II 89 is formed between the last nanofiltration membrane 3 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the alkali chamber 24, the outlet of the alkali chamber 24 is connected to the inlet of an alkali tank 60, the outlet of the alkali tank 60 is connected to an alkali circulating pump 61, the outlet of the alkali circulating pump 61 is connected to the inlet of the alkali chamber 24 to form a circulation, and the alkali tank 60 is further provided with a water inlet pipe 83 and an overflow port 84; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 passes through the water inlet circulating pump 43 and the water inlet chamber 5 and returns to the water inlet tank 42 to form circulation, and the water solution overflows from the overflow port 45 and is discharged; the pure water enters the alkali tank 60 from the water inlet pipe 83 of the alkali tank 60, the solution in the alkali tank 60 returns to the alkali tank 60 through the alkali circulating pump 61 and the alkali chamber 24 to form circulation, and overflows and is discharged from the overflow port 84; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. II-1 and FIG. II-1 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; supplying pure water from the water inlet pipe 83 of the alkali tank 60, and starting the alkali circulating pump 61 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1.5-2 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.7mol/L, sodium ion is 3.9%, barium ion can not be detected, and chloride ion is 29ppm, which is alkali corresponding to univalent cation.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 1-1.5 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.3mol/L, the concentration of sodium ion is 2.8%, sulfate radical can not be detected, and chloride ion is 43ppm, and is alkali corresponding to univalent cation.

And (4) conclusion: the flow of the water inlet pipe 83 is controlled by detecting the hydroxyl concentration of the alkali tank 60 to ensure that the hydroxyl concentration of the alkali tank 60 is = 0.8-1.2 mol/L, and the product obtained by overflowing the alkali tank 60 from the overflow port 84 is analyzed as follows: the concentration of hydroxide radical is 1.0mol/L, the concentration of sodium ion is 2.3%, the concentration of chloride ion is 26ppm, and the alkali is corresponding to univalent cation.

Example II-2

As shown in fig. v-8, fig. iv-1, fig. iv-6, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a nanofiltration membrane 3 and a bipolar membrane 21, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electricity meter control system, a pump, a tank, and the like.

The arrangement mode is that an electrode

positive plate

33, 10 repeated ' nanofiltration membrane 3, bipolar membrane 21 ' combinations, nanofiltration membrane 3 and an electrode negative plate 34 ' are arranged in sequence, and two sides of each membrane are provided with a partition plate 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the nanofiltration membrane 3, a water inlet chamber 5 is formed between the nanofiltration membrane 3 and the bipolar membrane 21, and an acid chamber 25 is formed between the bipolar membrane 21 and the nanofiltration membrane 3, so that a water chamber II 89 is formed between the last nanofiltration membrane 3 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the acid chamber 25, the outlet of the acid chamber 25 is connected to the inlet of the acid tank 54, the outlet of the acid tank 54 is connected to the acid circulating pump 55, the outlet of the acid circulating pump 55 is connected to the inlet of the acid chamber 25 to form a circulation, and the acid tank 54 is further provided with a water inlet pipe 77 and an overflow port 78; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 passes through the water inlet circulating pump 43 and the water inlet chamber 5 and returns to the water inlet tank 42 to form circulation, and the water solution overflows from the overflow port 45 and is discharged; pure water enters the acid tank 54 from a water inlet pipe 77 of the acid tank 54, and the solution in the acid tank 54 returns to the acid tank 54 through the acid circulating pump 55 and the acid chamber 25 to form circulation and is discharged from an overflow port 78 in an overflowing manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. II-2 and FIG. II-2-1 )

1mol/L hydrochloric acid is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the aqueous solution to be treated from a water inlet pipe 44 of the water inlet tank 42 and starting a water inlet circulating pump 43 for circulation; pure water is supplied from a water inlet pipe 77 of the acid tank 54, and an acid circulating pump 55 is started to circulate; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

And (4) conclusion: the hydrogen ion concentration of the acid tank 54 is detected to control the flow of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.3-1.7 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.4mol/L, sodium ions were 54ppm, barium ions were not detected, and chloride ions were 5% and were acids corresponding to monovalent anions.

And (4) conclusion: the hydrogen ion concentration of the acid tank 54 is detected to control the flow rate of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 1.3-1.7 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the concentration of hydrogen ions was 1.6mol/L, sodium ions were 65ppm, sulfate groups were not detected, and chloride ions were 5.7% and were acids corresponding to monovalent anions.

And (4) conclusion: the hydrogen ion concentration of the acid tank 54 is detected to control the flow of the water inlet pipe 77, so as to ensure that the hydrogen ion concentration of the acid tank 54 is = 0.8-1.3 mol/L, and the product obtained by overflowing the acid tank 54 from the overflow port 78 is analyzed as follows: the hydrogen ion concentration was 1.0mol/L, the sodium ion concentration was 33ppm, and the chloride ion concentration was 3.5%, which is an acid corresponding to a monovalent anion.

Examples II to 3

As shown in fig. v-9, fig. iv-1, fig. iv-10, fig. iv-11, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly comprises a membrane stack and accessory equipment, the membrane stack mainly comprises a bipolar membrane 21, an anode membrane 4, and a nanofiltration membrane 3, the accessory equipment mainly comprises an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member is used for clamping the membranes), a sealing member (in all embodiments, the sealing member is used for sealing each chamber formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrical instrument control system, a pump, a tank, and the like.

The arrangement mode is that an electrode positive plate 33, an anode membrane 4, a

nanofiltration membrane

3, 10 repeated combinations of a bipolar membrane 21, an anode membrane 4 and a nanofiltration membrane 3, the bipolar membrane 21, the anode membrane 4 and an electrode negative plate 34 are arranged in sequence, and two sides of each membrane are respectively provided with a partition plate 37.

The film stack forming equipment is utilized: according to the sequence of the direction of the electrode positive plate 33 → the direction of the electrode negative plate 34, an electrode water chamber I68 is formed between the electrode positive plate 33 and the anode membrane 4, an alkali chamber I26 is formed between the anode membrane 4 and the nanofiltration membrane 3, an alkali chamber II 27 is formed between the nanofiltration membrane 3 and the bipolar membrane 21, and an inlet water chamber 5 is formed between the bipolar membrane 21 and the anode membrane 4, so that the last anode membrane 4 and the electrode negative plate 34 repeatedly form an electrode water chamber II 89.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the first alkali chamber 26, the outlet of the first alkali chamber 26 is connected to the inlet of the first alkali tank 62, the outlet of the first alkali tank 62 is connected to the first alkali circulating pump 63, the outlet of the first alkali circulating pump 63 is connected to the inlet of the first alkali chamber 26 to form a circulation, and the first alkali tank 62 is further provided with a water inlet pipe 85 and an overflow port 86; for the second alkali chamber 27, the outlet of the second alkali chamber 27 is connected to the inlet of the second alkali tank 64, the outlet of the second alkali tank 64 is connected to the second alkali circulating pump 65, the outlet of the second alkali circulating pump 65 is connected to the inlet of the second alkali chamber 27 to form a circulation, and the second alkali tank 64 is further provided with a water inlet pipe 87 and an overflow port 88; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; the pure water enters the first alkali tank 62 from the water inlet pipe 85 of the first alkali tank 62, and the solution in the first alkali tank 62 returns to the first alkali tank 62 through the first alkali circulating pump 63 and the first alkali chamber 26 to form circulation and is discharged from the overflow port 86 in an overflow manner; the pure water enters the second alkali tank 64 from the water inlet pipe 87 of the second alkali tank 64, and the solution in the second alkali tank 64 returns to the second alkali tank 64 through the second alkali circulating pump 65 and the second alkali chamber 27 to form circulation and is discharged from the overflow port 88 in an overflow manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. II-3 and FIG. II-3-1 )

1mol/L sodium hydroxide is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; supplementing pure water from a water inlet pipe 85 of the first alkali tank 62, and starting a first alkali circulating pump 63 for circulation; supplying pure water from a water inlet pipe 87 of the second alkali tank 64, and starting a second alkali circulating pump 65 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V. Experiment 1: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, divalent cations and univalent anions, pure water is used for preparing an aqueous solution containing 2% of sodium chloride and 2% of barium chloride, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44, so that the salt concentration = 0.2-0.25 mol/L equivalent (converted into univalent ions) in the water inlet tank 42 is ensured.

And (4) conclusion: the flow of the water inlet pipe 85 is controlled by detecting the hydroxyl concentration of the first alkali tank 62 to ensure that the hydroxyl concentration of the first alkali tank 62 is = 1-1.5 mol/L, and the product obtained by overflowing the first alkali tank 62 from the overflow port 86 is analyzed as follows: the concentration of hydroxide radical is 1.1mol/L, the concentration of sodium ion is 5102ppm, the concentration of barium ion is 6.1%, the concentration of chloride ion is 68ppm, which is mainly alkali corresponding to the formation of divalent cation, and also contains alkali corresponding to low-concentration monovalent cation;

the flow of the water inlet pipe 87 is controlled by detecting the hydroxide concentration of the second alkali tank 64 to ensure that the hydroxide concentration of the second alkali tank 64 is = 1-1.5 mol/L, and the product obtained by overflowing the second alkali tank 64 from the overflow port 88 is analyzed as follows: the concentration of hydroxide radical is 1.2mol/L, the concentration of sodium ion is 2.8%, barium ion can not be detected, and chloride ion is 15ppm, and is alkali corresponding to univalent cation.

Examples II to 4

As shown in fig. v-10, fig. iv-1, fig. iv-7, fig. iv-8, fig. iv-14, and fig. vi, a bipolar membrane apparatus mainly includes a membrane stack mainly including a negative membrane 11, a bipolar membrane 21, and a nanofiltration membrane 3, and an auxiliary apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electricity meter control system, a pump, a tank, and the like.

The arrangement mode is that an electrode

positive plate

33, 10 repeated negative membrane 11, a bipolar membrane 21, a nanofiltration membrane 3 combination, a negative membrane 11 and an electrode negative plate 34 are arranged in sequence, and two sides of each membrane are respectively provided with a clapboard 37.

The film stack forming equipment is utilized: according to the sequence of the direction of the electrode positive plate 33 → the direction of the electrode negative plate 34, an electrode water chamber I68 is formed between the electrode positive plate 33 and the negative membrane 11, a water inlet chamber 5 is formed between the negative membrane 11 and the bipolar membrane 21, an acid chamber I28 is formed between the bipolar membrane 21 and the nanofiltration membrane 3, and an acid chamber II 29 is formed between the nanofiltration membrane 3 and the negative membrane 11, so that the electrode water chamber II 89 is formed between the last negative membrane 11 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the acid chamber I28, the outlet of the acid chamber I28 is connected to the inlet of the acid tank I56, the outlet of the acid tank I56 is connected to the acid circulating pump I57, the outlet of the acid circulating pump I57 is connected to the inlet of the acid chamber I28 to form a circulation, and the acid tank I56 is further provided with a water inlet pipe 79 and an overflow port 80; for the second acid chamber 29, the outlet of the second acid chamber 29 is connected to the inlet of the second acid tank 58, the outlet of the second acid tank 58 is connected to the second acid circulating pump 59, the outlet of the second acid circulating pump 59 is connected to the inlet of the second acid chamber 29 to form a circulation, and the second acid tank 58 is further provided with a water inlet pipe 81 and an overflow port 82; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The bipolar membrane device described above operates as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; pure water enters the first acid tank 56 from a water inlet pipe 79 of the first acid tank 56, and the solution in the first acid tank 56 returns to the first acid tank 56 through a first acid circulating pump 57 and a first acid chamber 28 to form circulation and is discharged from an overflow port 80 in an overflow manner; the pure water enters the second acid tank 58 from the water inlet pipe 81 of the second acid tank 58, and the solution in the second acid tank 58 returns to the second acid tank 58 through the second acid circulating pump 59 and the second acid chamber 29 to form circulation and is discharged from the overflow port 82 in an overflow manner; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. II-4 and FIG. II-4-1 )

1mol/L hydrochloric acid is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the aqueous solution to be treated from a water inlet pipe 44 of the water inlet tank 42 and starting a water inlet circulating pump 43 for circulation; supplying pure water from a water inlet pipe 79 of the first acid tank 56, and starting a first acid circulating pump 57 for circulation; supplying pure water from a water inlet pipe 81 of the second acid tank 58, and starting a second acid circulating pump 59 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

And (4) conclusion: the hydrogen ion concentration of the first acid tank 56 is detected to control the flow of the water inlet pipe 79, so as to ensure that the hydrogen ion concentration of the first acid tank 56 is = 1.5-2 mol/L, and the product obtained by overflowing the first acid tank 56 from the overflow port 80 is analyzed as follows: the concentration of hydrogen ions is 1.6mol/L, the concentration of sodium ions is 9ppm, sulfate radicals cannot be detected, and chloride ions are 5.5 percent and are acids corresponding to univalent anions;

the hydrogen ion concentration of the second acid tank 58 is detected to control the flow of the water inlet pipe 81, so as to ensure that the hydrogen ion concentration of the second acid tank 58 is = 1.5-2 mol/L, and the product obtained by overflowing the second acid tank 58 from the overflow port 82 is analyzed as follows: the concentration of hydrogen ions is 1.7mol/L, the concentration of sodium ions is 45ppm, the concentration of sulfate radicals is 6.7 percent, the concentration of chloride ions is 1 percent, the acid corresponding to divalent anions or more is mainly used, and the acid corresponding to a small amount of monovalent anions is also contained.

Example III-1

As shown in fig. v-11, iv-1, iv-2, iv-14 and vi, an electrodialysis apparatus mainly comprises a membrane stack and accessory equipment, wherein the membrane stack mainly comprises nanofiltration membrane 3 and an anode membrane 4, the accessory equipment mainly comprises an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member is used for clamping the membranes), a sealing member (in all embodiments, the sealing member is used for sealing each chamber formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrical instrument control system, a pump, a tank and the like.

The arrangement mode is that an electrode positive plate 33, an

anode membrane

4, 10 repeated combinations of 'a nanofiltration membrane 3 and an anode membrane 4' and an electrode negative plate 34 are arranged in sequence, and two sides of each membrane are provided with a clapboard 37.

The film stack forming equipment is utilized: according to the sequence of the direction of the electrode positive plate 33 → the direction of the electrode negative plate 34, an electrode water chamber I68 is formed between the electrode positive plate 33 and the anode membrane 4, a concentration chamber 6 is formed between the anode membrane 4 and the nanofiltration membrane 3, and a water inlet chamber 5 is formed between the nanofiltration membrane 3 and the anode membrane 4, so that the electrode water chamber II 89 is formed between the last anode membrane 4 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the concentration chamber 6, the outlet of the concentration chamber 6 is connected to the inlet of a concentration tank 46, the outlet of the concentration tank 46 is connected to a concentration circulating pump 47, the outlet of the concentration circulating pump 47 is connected to the inlet of the concentration chamber 6 to form a circulation, and the concentration tank 46 is further provided with a water inlet pipe 69 and an overflow port 70; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The electrodialysis apparatus described above was operated as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; the pure water enters the concentration tank 46 from a water inlet pipe 69 of the concentration tank 46, the solution in the concentration tank 46 returns to the concentration tank 46 through the concentration circulating pump 47 and the concentration chamber 6 to form circulation, and overflows and is discharged from an overflow port 70; the polar water in the polar water tank 66 returns to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. III-1 and FIG. III-1 )

1mol/L sodium chloride is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the aqueous solution to be treated from a water inlet pipe 44 of the water inlet tank 42 and starting a water inlet circulating pump 43 for circulation; supplying pure water from a water inlet pipe 69 of the concentration tank 46, and starting the concentration circulating pump 47 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with DC power at a voltage of 48V.

Experiment 1: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, divalent cations and univalent anions, pure water is used for preparing an aqueous solution containing 1% of sodium chloride and 1% of barium chloride, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44, so that the salt concentration = 0.1-0.15 mol/L equivalent (converted into univalent ions) in the water inlet tank 42 is ensured.

And (4) conclusion: the conductivity of the concentration tank 46 is detected to control the flow rate of the water inlet pipe 69, so as to ensure that the salt concentration = 0.7-1 mol/L equivalent (reduced to monovalent ion) concentration in the concentration tank 46, and the product obtained by overflowing the concentration tank 46 from the overflow port 70 is analyzed as follows: sodium ion 1.2%, barium ion 2%, and chloride ion 2.8%, and is a concentrated solution containing monovalent cation, divalent cation, and monovalent anion.

Experiment 2: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, divalent anions and univalent anions, pure water is used for preparing an aqueous solution containing 1% of sodium chloride and 1% of sodium sulfate, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44, so that the salt concentration = 0.1-0.15 mol/L equivalent (converted into univalent ions) in the water inlet tank 42 is ensured.

And (4) conclusion: the conductivity of the concentration tank 46 is detected to control the flow rate of the water inlet pipe 69, so as to ensure that the salt concentration = 0.7-1 mol/L equivalent (reduced to monovalent ion) concentration in the concentration tank 46, and the product obtained by overflowing the concentration tank 46 from the overflow port 70 is analyzed as follows: sodium ion 1.8%, chloride ion 2.7%, sulfate was not detected, and the concentrate contained monovalent cation and monovalent anion.

Experiment 3: aqueous solution to be treated: contains univalent positive ions and univalent negative ions, 1 percent of sodium chloride is prepared by pure water and is supplemented into a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44 so as to ensure that the salt concentration = 0.05-0.1 mol/L equivalent (converted into univalent ions) concentration in the water inlet tank 42.

And (4) conclusion: the conductivity of the concentration tank 46 is detected to control the flow rate of the water inlet pipe 69, so as to ensure that the salt concentration = 0.8-1.2 mol/L equivalent (converted into monovalent ion) concentration in the concentration tank 46, and the product obtained by overflowing the concentration tank 46 from the overflow port 70 is analyzed as follows: sodium ion 2.4%, chloride ion 3.6%, monovalent cation, monovalent anion containing concentrate.

Example III-2

As shown in fig. v-12, fig. iv-1, fig. iv-2, fig. iv-14, and fig. vi, an electrodialysis apparatus mainly includes a membrane stack mainly including a negative membrane 11 and a nanofiltration membrane 3, and an accessory apparatus mainly including a positive electrode plate 33, a negative electrode plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrical instrument control system, a pump, a tank, and the like.

The arrangement mode is that an electrode

positive plate

33, 10 repeated negative membrane 11, nanofiltration membrane 3 combinations, a negative membrane 11 and an electrode negative plate 34 are arranged in sequence, and the two sides of each membrane are provided with a clapboard 37.

The film stack forming equipment is utilized: according to the sequence of the direction of the electrode positive plate 33 → the direction of the electrode negative plate 34, an electrode water chamber I68 is formed between the electrode positive plate 33 and the negative membrane 11, a water inlet chamber 5 is formed between the negative membrane 11 and the nanofiltration membrane 3, a concentration chamber 6 is formed between the nanofiltration membrane 3 and the negative membrane 11, and accordingly, a water chamber II 89 is formed between the last negative membrane 11 and the electrode negative plate 34.

The electrodialysis apparatus described above was operated as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; the pure water enters the concentration tank 46 from a water inlet pipe 69 of the concentration tank 46, the solution in the concentration tank 46 returns to the concentration tank 46 through the concentration circulating pump 47 and the concentration chamber 6 to form circulation, and overflows and is discharged from an overflow port 70; the polar water in the polar water tank 66 is returned to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form a circulation.

The experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. III-2 and FIG. III-2-1 )

1mol/L sodium chloride is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; pure water is supplied from a water inlet pipe 69 of the concentration tank 46, and a concentration circulating pump 47 is started to circulate; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

And (4) conclusion: the conductivity of the concentration tank 46 is detected to control the flow rate of the water inlet pipe 69, so as to ensure that the salt concentration = 1.5-2 mol/L equivalent (reduced to monovalent ion) concentration in the concentration tank 46, and the product obtained by overflowing the concentration tank 46 from the overflow port 70 is analyzed as follows: sodium ion 4.1%, chloride ion 6.2%, barium ion was not detected, and the concentrate contained monovalent cation and monovalent anion.

And (4) conclusion: the conductivity of the concentration tank 46 is detected to control the flow rate of the water inlet pipe 69, so as to ensure that the salt concentration = 2-2.5 mol/L equivalent (reduced to monovalent ion) concentration in the concentration tank 46, and the product obtained by overflowing the concentration tank 46 from the overflow port 70 is analyzed as follows: sodium ion 5.3%, chloride ion 3.5%, sulfate radical 6.2%, is a concentrated solution containing monovalent cation, monovalent anion, and divalent anion.

And (4) conclusion: the conductivity of the concentration tank 46 is detected to control the flow rate of the water inlet pipe 69, so as to ensure that the salt concentration = 1-1.3 mol/L equivalent (reduced to monovalent ion) concentration in the concentration tank 46, and the product obtained by overflowing the concentration tank 46 from the overflow port 70 is analyzed as follows: sodium ion 2.6%, chloride ion 4%, containing monovalent cation, monovalent anion concentrate.

Examples III to 3

As shown in fig. v-13, fig. iv-1, fig. iv-3, fig. iv-4, fig. iv-14, and fig. vi, an electrodialysis apparatus mainly includes a membrane stack mainly including a negative membrane 11, a positive membrane 4, and a nanofiltration membrane 3, and an auxiliary apparatus mainly including a positive electrode plate 33, a negative electrode plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrical instrument control system, a pump, a tank, and the like.

The arrangement mode is that an electrode

positive plate

33, 10 repeated negative membrane sheets 11, positive membrane sheets 4, nanofiltration membrane sheets 3, negative membrane sheets 11 and electrode negative plates 34 are arranged in sequence, and two sides of each membrane sheet are provided with a partition plate 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the negative membrane 11, a water inlet chamber 5 is formed between the negative membrane 11 and the positive membrane 4, a concentration chamber I12 is formed between the positive membrane 4 and the nanofiltration membrane 3, a concentration chamber II 13 is formed between the nanofiltration membrane 3 and the negative membrane 11, and accordingly, the steps are repeated, and an electrode water chamber II 89 is formed between the last negative membrane 11 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the first concentrating chamber 12, the outlet of the first concentrating chamber 12 is connected to the inlet of a first concentrating tank 48, the outlet of the first concentrating tank 48 is connected to a first concentrating circulating pump 49, the outlet of the first concentrating circulating pump 49 is connected to the inlet of the first concentrating chamber 12 to form a circulation, and the first concentrating tank 48 is further provided with a water inlet pipe 71 and an overflow port 72; for the second concentrating chamber 13, the outlet of the second concentrating chamber 13 is connected to the inlet of the second concentrating tank 50, the outlet of the second concentrating tank 50 is connected to a second concentrating circulating pump 51, the outlet of the second concentrating circulating pump 51 is connected to the inlet of the second concentrating chamber 13 to form a circulation, and the second concentrating tank 50 is further provided with a water inlet pipe 73 and an overflow port 74; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The electrodialysis apparatus described above was operated as follows:

the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 returns to the water inlet tank 42 through the water inlet circulating pump 43 and the water inlet chamber 5 to form circulation, and overflows and is discharged from the overflow port 45; the pure water enters the first concentration tank 48 from a water inlet pipe 71 of the first concentration tank 48, and the solution in the first concentration tank 48 passes through a first concentration circulating pump 49 and a first concentration chamber 12 and then returns to the first concentration tank 48 to form circulation and is discharged from an overflow port 72 in an overflow manner; the pure water enters the second concentration tank 50 from the water inlet pipe 73 of the second concentration tank 50, and the solution in the second concentration tank 50 returns to the second concentration tank 50 through the second concentration circulating pump 51 and the second concentration chamber 13 to form circulation and is discharged from the overflow port 74 in an overflow manner; the polar water in the polar water tank 66 returns to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form circulation;

the experiment was run using the apparatus consisting of the membrane stack described above: ( Diagram corresponding to the principle of action: FIG. III-3, FIG. III-3-1, FIG. III-3-2 )

1mol/L sodium chloride is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; supplying pure water from a water inlet pipe 71 of the first concentration tank 48, and starting a first concentration circulating pump 49 for circulation; supplying pure water from a water inlet pipe 73 of the second concentration tank 50, and starting a second concentration circulating pump 51 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

Experiment 1: aqueous solution to be treated: the water-soluble salt-free water-saving agent comprises univalent cations, divalent cations and univalent anions, pure water is prepared into an aqueous solution containing 1% of sodium chloride and 1% of barium chloride, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44 so as to ensure that the salt concentration = 0.1-0.15 mol/L equivalent (converted into univalent ions) concentration in the water inlet tank 42.

And (4) conclusion: the conductivity of the second concentration tank 50 is detected to control the flow rate of the water inlet pipe 73, so as to ensure that the salt concentration = 1.5-2 mol/L equivalent (converted into monovalent ion) concentration in the second concentration tank 50, and the product obtained by overflowing the second concentration tank 50 from the overflow port 74 is analyzed as follows: sodium ion 4%, chloride ion 6.2%, barium ion can not be detected, it is a concentrate containing univalent cation, univalent anion; the conductivity of the first concentration tank 48 is detected to control the flow rate of the water inlet pipe 71, so as to ensure that the salt concentration = 1-1.5 mol/L equivalent (converted into monovalent ion) concentration in the first concentration tank 48, and the product obtained by overflowing the first concentration tank 48 from the overflow port 72 is analyzed as follows: 2510ppm of sodium ion, 4.1 ppm of chloride ion and 6.9% of barium ion, and is a concentrated solution mainly containing divalent cations, a small amount of monovalent cations and corresponding monovalent anions;

Experiment 2: aqueous solution to be treated: the water-saving salt-free water-saving agent comprises univalent cations, divalent anions and univalent anions, pure water is prepared into an aqueous solution containing 1% of sodium chloride and 1% of sodium sulfate, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44 so as to ensure that the salt concentration = 0.1-0.15 mol/L equivalent (converted into univalent ions) concentration in the water inlet tank 42.

And (4) conclusion: the conductivity of the second concentration tank 50 is detected to control the flow rate of the water inlet pipe 73, so as to ensure that the salt concentration = 1-1.5 mol/L equivalent (converted into monovalent ion) concentration in the second concentration tank 50, and the product obtained by overflowing the second concentration tank 50 from the overflow port 74 is analyzed as follows: 3.1 percent of sodium ions, 3876ppm of chloride ions and 5.9 percent of sulfate radicals, and is a concentrated solution mainly containing more than or equal to divalent anions, a small amount of monovalent anions and corresponding monovalent cations; the conductivity of the first concentration tank 48 is detected to control the flow rate of the water inlet pipe 71, so as to ensure that the salt concentration = 1-1.5 mol/L equivalent (converted into monovalent ion) concentration in the first concentration tank 48, and the product obtained by overflowing the first concentration tank 48 from the overflow port 72 is analyzed as follows: sodium ion 3.2%, chloride ion 4.8%, sulfate was not detected, and the concentrate contained monovalent cation and monovalent anion.

Examples III to 4

As shown in fig. v-14, fig. iv-1, fig. iv-3, fig. iv-4, fig. iv-5, fig. iv-14, and fig. vi, an electrodialysis apparatus mainly includes a membrane stack mainly including a negative membrane 11, a positive membrane 4, a first nanofiltration membrane 15, and a second nanofiltration membrane 16, and an accessory apparatus mainly including an electrode positive plate 33, an electrode negative plate 34, a clamping member (in all embodiments, the clamping member functions to clamp the membranes), a sealing member (in all embodiments, the sealing member functions to seal respective chambers formed by the electrodes and the membranes to prevent leakage), a fixing member, a power supply, an electrometer control system, a pump, a tank, and the like.

The arrangement mode is that the

positive electrode plate

33, 10 repeated negative membrane 11, positive membrane 4, first nanofiltration membrane 15, second nanofiltration membrane 16 are combined, the negative membrane 11 and the negative electrode plate 34 are arranged, and the two sides of each membrane are provided with a partition board 37.

The film stack forming equipment is utilized: according to the sequence of the electrode positive plate 33 direction → the electrode negative plate 34 direction, an electrode water chamber I68 is formed between the electrode positive plate 33 and the negative membrane 11, a water inlet chamber 5 is formed between the negative membrane 11 and the positive membrane 4, a concentration chamber I12 is formed between the positive membrane 4 and the first nanofiltration membrane 15, a concentration chamber II 13 is formed between the first nanofiltration membrane 15 and the second nanofiltration membrane 16, a concentration chamber III 14 is formed between the second nanofiltration membrane 16 and the negative membrane 11, and accordingly, the electrode water chamber II 89 is formed between the last negative membrane 11 and the electrode negative plate 34.

For the water inlet chamber 5, the outlet of the water inlet chamber 5 is connected to the inlet of the water inlet tank 42, the outlet of the water inlet tank 42 is connected to the water inlet circulating pump 43, the outlet of the water inlet circulating pump 43 is connected to the inlet of the water inlet chamber 5 to form a circulation, and the water inlet tank 42 is further provided with a water inlet pipe 44 and an overflow port 45; for the first concentrating chamber 12, the outlet of the first concentrating chamber 12 is connected to the inlet of a first concentrating tank 48, the outlet of the first concentrating tank 48 is connected to a first concentrating circulating pump 49, the outlet of the first concentrating circulating pump 49 is connected to the inlet of the first concentrating chamber 12 to form a circulation, and the first concentrating tank 48 is further provided with a water inlet pipe 71 and an overflow port 72; for the second concentrating chamber 13, the outlet of the second concentrating chamber 13 is connected to the inlet of the second concentrating tank 50, the outlet of the second concentrating tank 50 is connected to a second concentrating circulating pump 51, the outlet of the second concentrating circulating pump 51 is connected to the inlet of the second concentrating chamber 13 to form a circulation, and the second concentrating tank 50 is further provided with a water inlet pipe 73 and an overflow port 74; for the third concentrating chamber 14, the outlet of the third concentrating chamber 14 is connected to the inlet of the third concentrating tank 52, the outlet of the third concentrating tank 52 is connected to the third concentrating circulating pump 53, the outlet of the third concentrating circulating pump 53 is connected to the inlet of the third concentrating chamber 14 to form a circulation, and the third concentrating tank 52 is further provided with a water inlet pipe 75 and an overflow port 76; for the polar water chamber I68, the outlet of the polar water chamber I68 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber I68 to form a cycle; for the polar water chamber II 89, the outlet of the polar water chamber II 89 is connected to the inlet of the polar water tank 66, the outlet of the polar water tank 66 is connected to the polar water pump 67, and the outlet of the polar water pump 67 is connected to the inlet of the polar water chamber II 89 to constitute a cycle.

The electrodialysis apparatus described above was operated as follows: the water solution to be treated enters the water inlet tank 42 from the water inlet pipe 44 of the water inlet tank 42, the water solution in the water inlet tank 42 passes through the water inlet circulating pump 43 and the water inlet chamber 5 and returns to the water inlet tank 42 to form circulation, and the water solution overflows from the overflow port 45 and is discharged; the pure water enters the first concentration tank 48 from a water inlet pipe 71 of the first concentration tank 48, and the solution in the first concentration tank 48 passes through a first concentration circulating pump 49 and a first concentration chamber 12 and then returns to the first concentration tank 48 to form circulation and is discharged from an overflow port 72 in an overflow manner; the pure water enters the second concentration tank 50 from the water inlet pipe 73 of the second concentration tank 50, and the solution in the second concentration tank 50 passes through the second concentration circulating pump 51 and the second concentration chamber 13 and returns to the second concentration tank 50 to form circulation and is discharged from the overflow port 74 in an overflowing manner; pure water enters the third concentration tank 52 from a water inlet pipe 75 of the third concentration tank 52, and the solution in the third concentration tank 52 passes through a third concentration circulating pump 53 and a third concentration chamber 14 and returns to the third concentration tank 52 to form circulation and is discharged from an overflow port 76 in an overflowing manner; the polar water in the polar water tank 66 returns to the polar water tank 66 through the polar water pump 67, the polar water chamber I68 and the polar water chamber II 89 to form circulation;

the experiment was run using the apparatus consisting of the membrane stack described above: (diagram corresponding to principle of action: FIG. III-4)

1mol/L sodium chloride is filled into the polar water tank 66 to start the polar water pump 67 to circulate; feeding the water solution to be treated from a water inlet pipe 44 of the water inlet tank 42, and starting a water inlet circulating pump 43 for circulation; supplying pure water from a water inlet pipe 71 of the first concentration tank 48, and starting a first concentration circulating pump 49 for circulation; supplying pure water from a water inlet pipe 73 of the second concentration tank 50, and starting a second concentration circulating pump 51 for circulation; supplying pure water from a water inlet pipe 75 of the third concentration tank 52, and starting a third concentration circulating pump 53 for circulation; the positive electrode plate 33 and the negative electrode plate 34 are supplied with a direct current at a voltage of 48V.

And (4) conclusion: the conductivity of the second concentration tank 50 is detected to control the flow of the water inlet pipe 73, so as to ensure that the salt concentration in the second concentration tank 50 is = 0.7-1 mol/L equivalent (converted into monovalent ion) concentration, and the product obtained by overflowing from the overflow port 74 by the second concentration tank 50 is analyzed as follows: 2% of sodium ions, 2.9% of chloride ions and barium ions which cannot be detected are concentrated solution containing univalent cations and univalent anions; the conductivity of the third concentration tank 52 is detected to control the flow of the water inlet pipe 75, so as to ensure that the salt concentration = 0.5-1 mol/L equivalent (reduced to monovalent ions) concentration in the third concentration tank 52, and the product obtained by overflowing the third concentration tank 52 from the overflow port 76 is analyzed as follows: 1.8% of sodium ions, 2.7% of chloride ions and barium ions which cannot be detected are concentrated solution containing univalent cations and univalent anions; detecting the conductivity of the first concentration tank 48 to control the flow of the water inlet pipe 71, so as to ensure that the salt concentration in the first concentration tank 48 is = 1-1.5 mol/L equivalent (converted into univalent ions), and analyzing the product obtained by overflowing the first concentration tank 48 from the overflow port 72 as follows: 3345ppm of sodium ions, 4.2 ppm of chloride ions and 7.1 percent of barium ions, and is a concentrated solution mainly containing more than or equal to divalent cations and also containing a small amount of monovalent cations and corresponding monovalent anions.

And (4) conclusion: the conductivity of the third concentrating tank 52 is detected to control the flow rate of the water inlet pipe 75, so as to ensure that the salt concentration = 0.7-1.3 mol/L equivalent (converted into monovalent ion) concentration in the third concentrating tank 52, and the product obtained by overflowing the third concentrating tank 52 from the overflow port 76 is analyzed as follows: 1.9 percent of sodium ions, 2785ppm of chloride ions and 3.9 percent of sulfate radicals, and is a concentrated solution mainly containing more than or equal to divalent anions, a small amount of monovalent anions and corresponding monovalent cations; the conductivity of the first concentration tank 48 is detected to control the flow of the water inlet pipe 71, so as to ensure that the salt concentration in the first concentration tank 48 is = 0.8-1.3 mol/L equivalent (converted into univalent ions), and the product obtained by overflowing the first concentration tank 48 from the overflow port 72 is analyzed as follows: 2.3% of sodium ions, 3.6% of chloride ions and 3.6% of sulfate radicals which can not be detected are concentrated solution containing univalent cations and univalent anions; the conductivity of the second concentration tank 50 is detected to control the flow rate of the water inlet pipe 73, so as to ensure that the salt concentration in the second concentration tank 50 is = 1-1.5 mol/L equivalent (converted into monovalent ion) concentration, and the product obtained by overflowing from the overflow port 74 by the second concentration tank 50 is analyzed as follows: sodium ion 3%, chloride ion 4.5%, sulfate was not detected, and the concentrate contained monovalent cation and monovalent anion.

Experiment 3: aqueous solution to be treated: the water-soluble salt-free water-saving agent contains univalent cations, bivalent anions and univalent anions, pure water is used for preparing an aqueous solution containing 2.34% of sodium chloride and 1.22% of magnesium sulfate, the aqueous solution is supplemented to a water inlet pipe 44 of a water inlet tank 42, and the conductivity of the water inlet tank 42 is detected to control the flow of the water inlet pipe 44 so as to ensure that the salt concentration = 0.05-0.1 mol/L equivalent (converted into univalent ions) in the water inlet tank 42.

And (4) conclusion: the conductivity of the third concentrating tank 52 is detected to control the flow rate of the water inlet pipe 75, so as to ensure that the salt concentration = 0.5-1 mol/L equivalent (converted into monovalent ion) concentration in the third concentrating tank 52, and the product obtained by overflowing the third concentrating tank 52 from the overflow port 76 is analyzed as follows: 1.6 percent of sodium ions, 3012ppm of chloride ions, 3.4 percent of sulfate radicals and a concentrated solution of magnesium ions which can not be detected, mainly containing more than or equal to divalent anions, a small amount of monovalent anions and corresponding monovalent cations; the conductivity of the first concentration tank 48 is detected to control the flow of the water inlet pipe 71, so as to ensure that the salt concentration in the first concentration tank 48 is = 0.8-1.3 mol/L equivalent (converted into univalent ions), and the product obtained by overflowing the first concentration tank 48 from the overflow port 72 is analyzed as follows: 2012ppm of sodium ions, 3.6 percent of chloride ions, 1.2 percent of magnesium ions and sulfate radicals which cannot be detected are mainly concentrated solution containing divalent cations or more and a small amount of monovalent cations and monovalent anions; the conductivity of the second concentration tank 50 is detected to control the flow rate of the water inlet pipe 73, so as to ensure that the salt concentration = 1-1.5 mol/L equivalent (converted into monovalent ion) concentration in the second concentration tank 50, and the product obtained by overflowing the second concentration tank 50 from the overflow port 74 is analyzed as follows: 2.8% of sodium ions, 4.3% of chloride ions, no sulfate ions and no magnesium ions, and is a concentrated solution containing monovalent cations and monovalent anions.

Example VII: (corresponding diagram: FIG. VII)

As shown in FIG. VII, a water treatment system mainly comprises an alkalization tank 102, an electrodialysis device 117 (corresponding to the electrodialysis device constructed by using the membrane stack described in example III-3), a bipolar membrane device' 118, and an acidification tank 109.

The connection mode is as follows: an aqueous solution discharge pipeline 101 of the tail gas absorption device is connected to an inlet of an alkalization tank 102, an outlet of the alkalization tank 102 is connected to a delivery pump I103, an outlet of the delivery pump I103 is connected to a water inlet pipe 44 of a water inlet tank 42 of an electrodialysis device 117 (the connection relationship of the components of the electrodialysis device 117 is the same as that of the embodiment III-3), an overflow port 45 of the water inlet tank 42 is connected to an inlet of a low-concentration water tank I104, an outlet of the low-concentration water tank I104 is connected to a high-pressure pump I105, an outlet of the high-pressure pump I105 is connected to a water inlet of a reverse osmosis membrane group I106, a fresh water discharge port 107 of the reverse osmosis membrane group I106 discharges, and a concentrated solution outlet 108 of the reverse osmosis membrane group I106 is connected to the water inlet pipe 44 of the water inlet tank 42 of the electrodialysis device 117;

the overflow port 72 of the first concentration tank 48 of the electrodialysis device 117 is connected to the inlet of the acidification tank 109, the outlet of the acidification tank 109 is connected to the delivery pump II 110, the outlet of the delivery pump II 110 is connected to the water inlet pipe 44 of the water inlet tank 42 of the bipolar membrane device '118 (conventional device), the overflow port 45 of the bipolar membrane device '118 is connected to the inlet of the low-concentration water tank II 122, the outlet of the low-concentration water tank II 122 is connected to the high-pressure pump II 123, the outlet of the high-pressure pump II 123 is connected to the water inlet of the reverse osmosis membrane group II 124, the fresh water discharge port 125 of the reverse osmosis membrane group II 124 discharges, and the concentrated solution outlet 126 of the reverse osmosis membrane group II 124 is connected to the water inlet pipe 44 of the water inlet tank 42 of the bipolar membrane device ' 118;

An overflow port 78 of an acid tank 54 of the bipolar membrane device' 118 is connected to an inlet of a product acid tank 111, an outlet of the product acid tank 111 is connected to an acid recycling pump 112 and an acid product pump 113, an outlet of the acid recycling pump 112 is connected to an inlet of an acidification tank 109 (namely, an acid adding unit), and an outlet of the acid product pump 113 is collected by a container;

an overflow port 84 of an alkali tank 60 of the bipolar membrane device' 118 is connected to an inlet of an alkali product tank 114, an outlet of the alkali product tank 114 is connected to an alkali recycling pump 115 and an alkali product pump 116, an outlet of the alkali recycling pump 115 is connected to an inlet of the alkalization tank 102 (namely, an alkali adding unit), and an outlet of the alkali product pump 116 is collected by a container;

the water treatment system described above operates as follows: after the aqueous solution to be treated provided by the aqueous solution discharge pipeline 101 of the tail gas absorption device enters the alkalization tank 102 and is added with alkali liquor provided by the alkali reuse pump 115 (when the device operates the alkali reuse pump 115 for the first time, fresh alkali is used for replacing the alkaline liquor), the pH value is adjusted, the aqueous solution is conveyed to the water inlet tank 42 of the electrodialysis device 117 through the conveying pump I103, the operation mode of the aqueous solution in the electrodialysis device 117 is the same as that of the embodiment III-3, in detail, the embodiment III-3 is shown in the embodiment III-3, the low-concentration aqueous solution discharged from the overflow port 45 of the water inlet tank 42 of the electrodialysis device 117 enters the low-concentration water tank I104 and is conveyed to the reverse osmosis membrane group I106 through the high-pressure pump I105 for concentration, the fresh water of the reverse osmosis membrane group I106 is discharged from the fresh water outlet 107, and the concentrated solution of the reverse osmosis membrane group I106 is conveyed to the water inlet tank 42 of the electrodialysis device 117 again, namely, the treatment is carried out through the electrodialysis device 117 again;

The concentrated solution in the concentration jar 48 of electrodialysis equipment 117 gets into acidizing jar 109 through overflow mouth 72, after acidizing jar 109 adds the acidizing fluid that acid retrieval and utilization pump 112 provided (device is run for the first time and is replaced with fresh acid when acid retrieval and utilization pump 112 does not have acidizing fluid) adjustment PH, carries the water inlet jar 42 of bipolar membrane equipment '118 through delivery pump II 110, and the running mode of aqueous solution is conventional prior art in bipolar membrane equipment' 118, also with the utility model discloses the similar no longer repeated description of the running mode of other bipolar membrane equipment;

the low-concentration water solution overflowing from the overflow port 45 of the water inlet tank 42 of the bipolar membrane device '118 enters the low-concentration water tank II 122, and is delivered to the reverse osmosis membrane group II 124 through the high-pressure pump II 123 for concentration, the fresh water discharge port 125 of the reverse osmosis membrane group II 124 discharges, and the concentrated solution at the concentrated solution outlet 126 of the reverse osmosis membrane group II 124 enters the water inlet tank 42 of the bipolar membrane device' 118; the product acid overflowing from the overflow port 78 of the acid tank 54 of the bipolar membrane device' 118 enters a finished product acid tank 111, and a part of the acid liquid in the finished product acid tank 111 is pumped to the acidification tank 109 for use through an acid recycling pump 112; another part of the acid liquid in the finished acid tank 111 is collected into a container (i.e. the finished acid) through an acid product pump 113; the product alkali overflowing from the overflow port 84 of the alkali tank 60 of the bipolar membrane device' 118 enters the finished product alkali tank 114, and a part of the alkali liquor in the finished product alkali tank 114 is pumped to the alkalization tank 102 for use through the alkali recycling pump 115; another portion of the alkali solution in the finished alkali tank 114 is collected into a container (i.e., the finished product alkali) by an alkali product pump 116.

The experiment was run using the apparatus consisting of the membrane stack described above: (corresponding diagram: FIG. VII)

For a tail gas washing tower in the terephthalic acid industry, an aqueous solution water sample to be treated is provided by an aqueous solution discharge pipeline 101 of a tail gas absorption device (namely, the tail gas washing tower uses sodium hydroxide as an absorption liquid to wash carbon dioxide, hydrogen bromide and the like in tail gas): PH =8.77, carbonate =1503ppm, bicarbonate =6528ppm, bromide =2373ppm, sodium =4415ppm;

the alkalization tank 102 is used for adding alkali to adjust the pH (adding fresh alkali at the initial stage, and then adding alkali of an alkali recycling pump 115) of the water sample: PH =10.5, carbonate =7245ppm, bicarbonate =105ppm, bromide =2135ppm, sodium =6647ppm;

the electrodialysis apparatus 117 was operated in the manner described in example III-3 (wherein the sodium bromide was charged in an aqueous polar tank at 1mol/L, the rest being the same), and the concentrate obtained in the first concentration tank 48 of the electrodialysis apparatus 117 was analyzed as follows: carbonate =87ppm, bicarbonate =487ppm, bromide =12013ppm, sodium =3745ppm;

sampling from an acidification tank 109: PH =2.5 (initial addition of fresh hydrobromic acid followed by addition of acid for reuse by pump 112), carbonate = undetectable, bicarbonate = undetected, bromide =14011ppm, sodium =3311ppm;

The polar water tank of the bipolar membrane equipment' 118 is filled with 1mol/L sodium hydroxide, and the voltage is 48V direct current.

The finished acid tank 111 was analyzed as follows: 1.5mol/L of hydrogen ions, 12.1% of bromide ions, and 212ppm of sodium ions, and hydrobromic acid is obtained;

the finished caustic tank 114 is analyzed as follows: hydroxide radical 1.1mol/L, sodium ion 2.5%, and bromide ion 177ppm to obtain sodium hydroxide.

Example viii: (corresponding diagram: FIG. VIII)

As shown in fig. vii, an aqueous solution treatment system mainly comprises a heating tank 121, a heater 120, a cooler 119, an electrodialysis device 117 (corresponding to the electrodialysis device constructed using the membrane stack described in example iii-3), a bipolar membrane device' 118, and an acidification tank 109.

The connection mode is as follows:

on the basis of the embodiment VII, the 'aqueous solution discharge pipeline 101 of the tail gas absorption device is connected to the inlet of the alkalization tank 102, the outlet of the alkalization tank 102 is connected to the delivery pump I103, the outlet of the delivery pump I103 is connected to the water inlet pipe 44 of the water inlet tank 42 of the electrodialysis device 117', instead, the 'aqueous solution discharge pipeline 101 of the tail gas absorption device is connected to the inlet of the heating tank 121, the heater 120 is arranged in the heating tank 121, the vent is arranged above the heater 120, the outlet of the heating tank 121 is connected to the delivery pump I103, the outlet of the delivery pump I103 is connected to the inlet of the cooler 119, and the outlet of the cooler 119 is connected to the water inlet pipe 44 of the water inlet tank 42 of the electrodialysis device 117'; the connection relationship of "the outlet of the product base tank 114 is connected to the base reuse pump 115 and the base product pump 116", the outlet of the base reuse pump 115 is connected to the inlet of the alkalization tank 102, the outlet of the base product pump 116 is collected by a container "instead of" the outlet of the product base tank 114 is connected to the base product pump 116, the outlet of the base product pump 116 is collected by a container ", and the rest of the connection relationship is the same as that of example vii.

The water treatment system described above operates as follows: on the basis of the example VII, after the pH value of the aqueous solution to be treated provided by the "aqueous solution discharge pipeline 101 of the tail gas absorption device" of the example VII is adjusted by adding lye provided by the alkali reuse pump 115 (the alkali reuse pump 115 is replaced by fresh alkali when the device operates for the first time without lye ") into the alkalization tank 102, the aqueous solution to be treated provided by the" aqueous solution discharge pipeline 101 of the tail gas absorption device "conveyed to the water inlet tank 42 of the electrodialysis device 117 through the conveying pump I103 is replaced by" the aqueous solution to be treated provided by the "aqueous solution discharge pipeline 101 of the tail gas absorption device is conveyed into the heating tank 121, the aqueous solution in the heating tank 121 is heated by the heater 120 (the generated gas is discharged from the vent above the heating tank 121), and the heated aqueous solution is pumped to the cooler 119 through the conveying pump I103 to be cooled and then conveyed to the water inlet tank 42 of the electrodialysis device 117"; part of the alkali liquor in the finished product alkali tank 114 of example VII is pumped into the alkalization tank 102 for use by an alkali recycling pump 115; the other part of the alkali liquor in the finished product alkali tank 114 is collected into the container through the alkali product pump 116 (namely, the final product alkali) is replaced by the operation of collecting the alkali liquor in the finished product alkali tank 114 into the container through the alkali product pump 116 (namely, the final product alkali), and the rest operation modes are the same as those in the embodiment VII.

The experiment was run using the apparatus consisting of the membrane stack described above: (corresponding diagram: FIG. VIII)

the temperature of the heating tank 121 is set to 95 ℃, the temperature of the outlet of the cooler 119 is set to 30 ℃ (cooled by 5 ℃ frozen water), and a water sample at the outlet of the cooler 119 is taken: carbonate =4612ppm, bicarbonate =1785ppm, bromide =2810ppm, sodium =5175ppm;

the electrodialysis apparatus 117 was operated in the manner described in example III-3 (wherein the sodium bromide was charged in an aqueous polar tank at 1mol/L, the rest being the same), and the concentrate obtained in the first concentration tank 48 of the electrodialysis apparatus 117 was analyzed as follows: carbonate =112ppm, bicarbonate =6859ppm, bromide =11856ppm, sodium =6128ppm;

sampling from an acidification tank 109: PH =2.5 (initial addition of fresh hydrobromic acid followed by addition of acid for reuse by pump 112), carbonate = undetectable, bicarbonate = undetectable, bromide =23856ppm, sodium =5513ppm;

The finished acid tank 111 was analyzed as follows: 1.3mol/L of hydrogen ions, 10.2% of bromide ions and 188ppm of sodium ions, and hydrobromic acid is obtained;

the finished caustic tank 114 is analyzed as follows: hydroxide radical 1.4mol/L, sodium ion 3.2%, bromide ion 151ppm, get sodium hydroxide.

Claims

1. A dialysis membrane stack, wherein the membrane stack is disposed between a positive electrode plate and a negative electrode plate:

the membrane stack comprises a bipolar membrane and a nanofiltration membrane, wherein the membranes in the membrane stack are arranged in the direction from an electrode positive plate to an electrode negative plate:

comprises at least one group of combination formed by a bipolar membrane and a nanofiltration membrane in turn;

or comprises at least one group of combination formed by nanofiltration membrane sheets and bipolar membrane sheets in turn;

or the membrane stack comprises a bipolar membrane, a nanofiltration membrane and an anode membrane and/or a cathode membrane, wherein the membranes in the membrane stack are arranged in the direction from an electrode positive plate to an electrode negative plate:

comprises at least one group of combination formed by a bipolar membrane, a negative membrane and a nanofiltration membrane in sequence;

or comprises at least one group of combination formed by a bipolar membrane, a nanofiltration membrane and an anode membrane in sequence;

Or comprises at least one group of combination formed by a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane in sequence;

or comprises at least one group of combination formed by a bipolar membrane, a nanofiltration membrane, a negative membrane and a positive membrane in sequence;

or comprises at least one group of combination formed by a bipolar membrane, a negative membrane, a positive membrane and a nanofiltration membrane in sequence;

or comprises at least one group of combination formed by a bipolar membrane, a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane in sequence;

or comprises at least one group of combination formed by a bipolar membrane, a positive membrane and a nanofiltration membrane in sequence;

or comprises at least one group of combination formed by a negative membrane, a bipolar membrane and a nanofiltration membrane in sequence;

or the membrane stack comprises nanofiltration membrane sheets and positive membrane sheets and/or negative membrane sheets, wherein the membrane sheets in the membrane stack are arranged in the direction from the electrode positive plate to the electrode negative plate:

comprises at least one group of combination formed by nanofiltration membrane and anode membrane in turn;

or comprises at least one group of combination formed by a negative membrane sheet and a nanofiltration membrane sheet in sequence;

or comprises at least one group of combination formed by a negative membrane, a positive membrane and a nanofiltration membrane in sequence;

or comprises at least one group of combination formed by a negative membrane sheet, a positive membrane sheet, a first nanofiltration membrane sheet and a second nanofiltration membrane sheet in sequence.

2. The membrane stack of claim 1, wherein the membrane sheets are arranged in order from the positive electrode plate to the negative electrode plate:

the membrane stack comprises at least one group of combinations formed by a bipolar membrane, a negative membrane and a nanofiltration membrane in sequence, wherein when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the membrane stack is a membrane stack I-1;

or the membrane stack comprises at least one group of combinations formed by a bipolar membrane, a nanofiltration membrane and an anode membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack I-2;

or the membrane stack comprises at least one group of combinations formed by a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack I-3;

or the membrane stack comprises at least one group of combinations formed by a bipolar membrane, a nanofiltration membrane, a negative membrane and a positive membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack I-4;

Or the membrane stack comprises at least one group of combinations formed by a bipolar membrane, a negative membrane, a positive membrane and a nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack I-5;

or the membrane stack comprises at least one group of combinations formed by a bipolar membrane, a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack I-6;

or the membrane stack comprises at least one group of combinations formed by the bipolar membrane and the nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, and the membrane stack is II-1;

or the membrane stack comprises at least one group of combinations formed by nanofiltration membranes and bipolar membranes in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack II-2;

or the membrane stack comprises at least one group of combinations formed by a bipolar membrane, an anode membrane and a nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack II-3;

Or the membrane stack comprises at least one group of combination formed by a negative membrane, a bipolar membrane and a nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack II-4;

or the membrane stack comprises at least one group of combinations formed by nanofiltration membranes and positive membranes in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack III-1;

or the membrane stack comprises at least one group of combinations formed by a negative membrane and a nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack III-2;

or the membrane stack comprises at least one group of combinations formed by a negative membrane, a positive membrane and a nanofiltration membrane in sequence, when more than or equal to two combinations are arranged, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack III-3;

or the membrane stack comprises at least one group of combinations formed by a negative membrane, a positive membrane, a first nanofiltration membrane and a second nanofiltration membrane in sequence, when the number of the combinations is more than or equal to two, the latter combination is close to the former combination and is arranged between the former combination and the electrode negative plate, namely the membrane stack III-4.

3. The membrane stack of claim 1, wherein:

the membrane stack comprises the following components in the direction from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the bipolar membrane, the negative membrane and the nanofiltration membrane are membrane stacks I-1-1;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the negative membrane, the nanofiltration membrane, the bipolar membrane and the negative membrane are membrane stacks I-1-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the bipolar membrane, the nanofiltration membrane and the positive membrane are the membrane stack I-2-1;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the anode membrane, the bipolar membrane and the nanofiltration membrane are membrane stacks I-2-2;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane are the membrane stack I-3-1;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the first nanofiltration membrane, the second nanofiltration membrane, the bipolar membrane and the first nanofiltration membrane are membrane stacks I-3-2;

Or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane are the membrane stack I-4-1;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the negative membrane, the positive membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane are the membrane stack I-4-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the negative membrane, the positive membrane, the bipolar membrane and the nanofiltration membrane are membrane stacks I-4-3;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane are membrane stacks I-5-1;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the nanofiltration membrane, the bipolar membrane, the negative membrane and the positive membrane are the membrane stack I-5-2;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: a negative membrane, a positive membrane, a nanofiltration membrane, a bipolar membrane and a negative membrane, namely a membrane stack I-5-3;

Or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane are membrane stacks I-6-1;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane and the positive membrane are the membrane stack I-6-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a negative membrane, namely a membrane stack I-6-3;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the membrane stack comprises a first nanofiltration membrane, a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane and a first nanofiltration membrane, namely a membrane stack I-6-4;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane are membrane stacks II-1-1;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane are membrane stacks II-2-1;

Or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the bipolar membrane, the anode membrane and the nanofiltration membrane are membrane stacks II-3-1;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the nanofiltration membrane, the bipolar membrane and the positive membrane are membrane stacks II-3-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the negative membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane are the membrane stack II-4-1;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane are membrane stacks II-4-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the nanofiltration membrane and the positive membrane are membrane stacks III-1-1;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the anode membrane and the nanofiltration membrane are membrane stacks III-1-2;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the negative membrane, the nanofiltration membrane and the negative membrane are membrane stacks III-2-1;

Or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the negative membrane and the nanofiltration membrane are membrane stacks III-2-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane, the negative membrane, the positive membrane and the nanofiltration membrane are membrane stacks III-3-1;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the nanofiltration membrane, the negative membrane and the positive membrane are membrane stacks III-3-2;

or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the negative membrane, the positive membrane, the nanofiltration membrane and the negative membrane are the membrane stack III-3-3;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: a negative membrane, a positive membrane, a first nanofiltration membrane, a second nanofiltration membrane and a negative membrane, namely a membrane stack III-4-1;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the positive membrane, the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane and the positive membrane are membrane stacks III-4-2;

or the membrane stack comprises the following components in sequence from the electrode positive plate to the electrode negative plate: the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane, the positive membrane and the first nanofiltration membrane are membrane stacks III-4-3;

Or the membrane stack comprises the following components arranged in sequence from the electrode positive plate to the electrode negative plate: the second nanofiltration membrane, the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane are membrane stacks III-4-4.

4. The membrane stack of claim 2, wherein: in the direction from the electrode positive plate to the electrode negative plate:

membrane stack I-1: a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane, the negative membrane and the nanofiltration membrane;

or a membrane stack I-1: a negative membrane and a nanofiltration membrane are sequentially arranged between the positive electrode plate and the first combination of the bipolar membrane, the negative membrane and the nanofiltration membrane, and a bipolar membrane and a negative membrane are sequentially arranged between the last combination of the bipolar membrane, the negative membrane and the nanofiltration membrane and the negative electrode plate;

or a membrane stack I-2: an anode membrane is arranged between the electrode positive plate and the combination of the first bipolar membrane, the nanofiltration membrane and the anode membrane;

or a membrane stack I-2: a nanofiltration membrane and an anode membrane are sequentially arranged between the positive electrode plate and the first combination of the bipolar membrane, the nanofiltration membrane and the anode membrane, and a bipolar membrane and a nanofiltration membrane are sequentially arranged between the last combination of the bipolar membrane, the nanofiltration membrane and the anode membrane and the negative electrode plate;

Or a membrane stack I-3: a second nanofiltration membrane is arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane;

or a membrane stack I-3: a first nanofiltration membrane and a second nanofiltration membrane are sequentially arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane, and a bipolar membrane and a first nanofiltration membrane are sequentially arranged between the combination of the last bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate;

or a membrane stack I-4: an anode membrane is arranged between the positive electrode plate and the first bipolar membrane, nanofiltration membrane, cathode membrane and anode membrane;

or a membrane stack I-4: a negative membrane and a positive membrane are sequentially arranged between the positive electrode plate and the first combination of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane, and a bipolar membrane, a nanofiltration membrane and a negative membrane are sequentially arranged between the last combination of the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane and the negative electrode plate;

or a membrane stack I-4: a nanofiltration membrane, a negative membrane and a positive membrane are sequentially arranged between the electrode positive plate and the first bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane, and a bipolar membrane and a nanofiltration membrane are sequentially arranged between the last bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane and the electrode negative plate;

Or a membrane stack I-5: a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane, the first negative membrane, the first positive membrane and the first nanofiltration membrane;

or a membrane stack I-5: the positive membrane and the nanofiltration membrane are sequentially arranged between the electrode positive plate and the first combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane, and the bipolar membrane, the negative membrane and the positive membrane are sequentially arranged between the last combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane and the electrode negative plate;

or a membrane stack I-5: a negative diaphragm, a positive diaphragm and a nanofiltration diaphragm are sequentially arranged between the positive electrode plate and the first combination of the bipolar diaphragm, the negative diaphragm, the positive diaphragm and the nanofiltration diaphragm, and a bipolar diaphragm and a negative diaphragm are sequentially arranged between the last combination of the bipolar diaphragm, the negative diaphragm, the positive diaphragm and the nanofiltration diaphragm and the negative electrode plate;

or a membrane stack I-6: a second nanofiltration membrane is arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane;

or a membrane stack I-6: a positive membrane and a second nanofiltration membrane are sequentially arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and a bipolar membrane, a first nanofiltration membrane, a negative membrane and a positive membrane are sequentially arranged between the combination of the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate;

Or a membrane stack I-6: a negative membrane, a positive membrane and a second nanofiltration membrane are sequentially arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and a bipolar membrane, a first nanofiltration membrane and a negative membrane are sequentially arranged between the combination of the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate;

or a membrane stack I-6: a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane are sequentially arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and a bipolar membrane and a first nanofiltration membrane are sequentially arranged between the combination of the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane and the negative electrode plate;

or a membrane stack II-1: a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane and the first nanofiltration membrane;

or a membrane stack II-2: a nanofiltration membrane is arranged between the combination of the last nanofiltration membrane and the bipolar membrane and the electrode negative plate;

Or a membrane stack II-3: a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane, the positive membrane and the nanofiltration membrane;

or a membrane stack II-3: the positive membrane and the nanofiltration membrane are sequentially arranged between the positive electrode plate and the first combination of the bipolar membrane, the positive membrane and the nanofiltration membrane, and the bipolar membrane and the positive membrane are sequentially arranged between the last combination of the bipolar membrane, the positive membrane and the nanofiltration membrane and the negative electrode plate;

or a membrane stack II-4: a negative membrane is arranged between the last negative membrane, the combination of the bipolar membrane and the nanofiltration membrane and the negative electrode plate;

or a membrane stack II-4: a nanofiltration membrane is arranged between the positive electrode plate and the first negative membrane, the bipolar membrane and the nanofiltration membrane;

or a membrane stack III-1: an anode membrane is arranged between the electrode positive plate and the combination of the first nanofiltration membrane and the anode membrane;

or a membrane stack III-1: a nanofiltration membrane is arranged between the combination of the last nanofiltration membrane and the anode membrane and the electrode negative plate;

or stack III-2: a negative membrane is arranged between the last negative membrane and the negative electrode plate;

Or a membrane stack III-2: a nanofiltration membrane is arranged between the positive electrode plate and the first negative membrane and nanofiltration membrane;

or a membrane stack III-3: a nanofiltration membrane is arranged between the positive electrode plate and the first negative membrane, the first positive membrane and the first nanofiltration membrane;

or a membrane stack III-3: an anode membrane and a nanofiltration membrane are sequentially arranged between the positive electrode plate and the first combination of the cathode membrane, the anode membrane and the nanofiltration membrane, and a cathode membrane and an anode membrane are sequentially arranged between the last combination of the cathode membrane, the anode membrane and the nanofiltration membrane and the negative electrode plate;

or a membrane stack III-3: a negative membrane is arranged between the last combination of the negative membrane, the positive membrane and the nanofiltration membrane and the negative electrode plate;

or a membrane stack III-4: a negative membrane is arranged between the last combination of the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate;

or a membrane stack III-4: an anode membrane, a first nanofiltration membrane and a second nanofiltration membrane are sequentially arranged between the electrode positive plate and the combination of the first cathode membrane, the first anode membrane, the first nanofiltration membrane and the second nanofiltration membrane, and an anode membrane are sequentially arranged between the combination of the last cathode membrane, the last anode membrane, the last first nanofiltration membrane and the last second nanofiltration membrane and the electrode negative plate;

Or a membrane stack III-4: a first nanofiltration membrane and a second nanofiltration membrane are sequentially arranged between the positive electrode plate and the combination of the first negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, and a negative membrane, a positive membrane and a first nanofiltration membrane are sequentially arranged between the combination of the last negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate;

or a membrane stack III-4: and a second nanofiltration membrane is arranged between the positive electrode plate and the combination of the first negative membrane, the first positive membrane, the first nanofiltration membrane and the second nanofiltration membrane.

5. The membrane stack of claim 2, 3 or 4, wherein for each membrane sheet:

the membrane stack I-1, the membrane stack I-1-1 or the membrane stack I-1-2 are arranged in the direction from the electrode positive plate to the electrode negative plate: an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the membrane stack I-2, the membrane stack I-2-1 or the membrane stack I-2-2 are arranged in the direction from the electrode positive plate to the electrode negative plate: an acid chamber is formed between the bipolar membrane and the nanofiltration membrane, a water inlet chamber is formed between the nanofiltration membrane and the anode membrane, and an alkali chamber is formed between the anode membrane and the bipolar membrane;

Or the film stack I-3, the film stack I-3-1 or the film stack I-3-2 are arranged in the direction from the electrode positive plate to the electrode negative plate: an acid chamber is formed between the bipolar membrane and the first nanofiltration membrane, a water inlet chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and an alkali chamber is formed between the second nanofiltration membrane and the bipolar membrane;

or the membrane stack I-4, the membrane stack I-4-1, the membrane stack I-4-2 or the membrane stack I-4-3 are arranged in the direction from the positive plate of the electrode to the negative plate of the electrode: an acid chamber I is formed between the bipolar membrane and the nanofiltration membrane, an acid chamber II is formed between the nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, and an alkali chamber is formed between the positive membrane and the bipolar membrane;

or the membrane stack I-5, the membrane stack I-5-1, the membrane stack I-5-2 or the membrane stack I-5-3 are arranged in the direction from the positive plate of the electrode to the negative plate of the electrode: an acid chamber is formed between the bipolar membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, a first alkali chamber is formed between the positive membrane and the nanofiltration membrane, and a second alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the membrane stack I-6, the membrane stack I-6-1, the membrane stack I-6-2, the membrane stack I-6-3 or the membrane stack I-6-4 are arranged in the direction from the positive electrode plate to the negative electrode plate of the electrode: an acid chamber II is formed between the bipolar membrane and the first nanofiltration membrane, an acid chamber I is formed between the first nanofiltration membrane and the negative membrane, a water inlet chamber is formed between the negative membrane and the positive membrane, an alkali chamber I is formed between the positive membrane and the second nanofiltration membrane, and an alkali chamber II is formed between the second nanofiltration membrane and the bipolar membrane;

Or the film stack II-1-1 is arranged from the direction of the electrode positive plate to the direction of the electrode negative plate: a water inlet chamber is formed between the bipolar membrane and the nanofiltration membrane, and an alkali chamber is formed between the nanofiltration membrane and the bipolar membrane;

or the film stack II-2-1 is arranged from the direction of the electrode positive plate to the direction of the electrode negative plate: a water inlet chamber is formed between the nanofiltration membrane and the bipolar membrane, and an acid chamber is formed between the bipolar membrane and the nanofiltration membrane;

or the film stack II-3, the film stack II-3-1 or the film stack II-3-2 is arranged from the direction of the electrode positive plate to the direction of the electrode negative plate: a water inlet chamber is formed between the bipolar membrane and the positive membrane, an alkali chamber I is formed between the positive membrane and the nanofiltration membrane, and an alkali chamber II is formed between the nanofiltration membrane and the bipolar membrane;

or the film stack II-4, the film stack II-4-1 or the film stack II-4-2 is arranged from the direction of the positive electrode plate to the direction of the negative electrode plate: a water inlet chamber is formed between the negative membrane and the bipolar membrane, an acid chamber I is formed in front of the bipolar membrane and the nanofiltration membrane, and an acid chamber II is formed between the nanofiltration membrane and the negative membrane;

or the film stack III-1, the film stack III-1-1 or the film stack III-1-2 is arranged from the direction of the electrode positive plate to the direction of the electrode negative plate: a water inlet chamber is formed between the nanofiltration membrane and the positive membrane, and a concentration chamber is formed between the positive membrane and the nanofiltration membrane;

Or the film stack III-2, the film stack III-2-1 or the film stack III-2-2 is arranged from the direction of the electrode positive plate to the direction of the electrode negative plate: a water inlet chamber is formed between the negative membrane and the nanofiltration membrane, and a concentration chamber is formed between the nanofiltration membrane and the negative membrane;

or the film stack III-3, the film stack III-3-1, the film stack III-3-2 or the film stack III-3-3 are arranged in the direction from the positive electrode plate to the negative electrode plate of the electrode: a water inlet chamber is formed between the negative membrane and the positive membrane, a first concentration chamber is formed between the positive membrane and the nanofiltration membrane, and a second concentration chamber is formed between the nanofiltration membrane and the negative membrane;

or the membrane stack III-4, the membrane stack III-4-1, the membrane stack III-4-2, the membrane stack III-4-3 or the membrane stack III-4-4 are arranged in the direction from the electrode positive plate to the electrode negative plate: a water inlet chamber is formed between the negative diaphragm and the positive diaphragm, a first concentration chamber is formed between the positive diaphragm and the first nanofiltration membrane, a second concentration chamber is formed between the first nanofiltration membrane and the second nanofiltration membrane, and a third concentration chamber is formed between the second nanofiltration membrane and the negative diaphragm;

or an electrode water chamber I is formed between the electrode positive plate and one membrane closest to the electrode positive plate, and an electrode water chamber II is formed between the electrode negative plate and one membrane closest to the electrode negative plate.

6. The membrane stack of claim 5, wherein:

when the membrane stack I-1-1 is sequentially provided with a nanofiltration membrane, a bipolar membrane, a cathode membrane and a nanofiltration membrane from an electrode positive plate to an electrode negative plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane, the negative membrane and the nanofiltration membrane is replaced by a positive membrane;

or when the membrane stack I-1-2 is sequentially provided with a negative membrane, a nanofiltration membrane, a bipolar membrane and a negative membrane from an electrode positive plate to an electrode negative plate: the negative membrane, the nanofiltration membrane, the bipolar membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane;

or when the membrane stack I-2-1 is sequentially provided with an anode membrane, a bipolar membrane, a nanofiltration membrane and an anode membrane from an electrode positive plate to an electrode negative plate: the positive membrane, the bipolar membrane, the nanofiltration membrane and the positive membrane close to the positive electrode plate and/or the negative electrode plate of the positive membrane are/is replaced by the nanofiltration membrane;

or when the membrane stack I-2-2 is sequentially provided with a nanofiltration membrane, an anode membrane, a bipolar membrane and a nanofiltration membrane from an electrode positive plate to an electrode negative plate: the nanofiltration membrane, the anode membrane, the bipolar membrane and the nanofiltration membrane close to the electrode positive plate and/or the electrode negative plate in the nanofiltration membrane are replaced by the cathode membrane;

Or when the membrane stack I-3-1 is sequentially provided with a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a second nanofiltration membrane from an electrode positive plate to an electrode negative plate: the second nanofiltration membrane close to the positive electrode plate and/or the second nanofiltration membrane close to the negative electrode plate in the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane is replaced by a positive membrane;

or when the membrane stack I-3-2 is provided with a first nanofiltration membrane, a second nanofiltration membrane, a bipolar membrane and a first nanofiltration membrane in sequence from the positive electrode plate to the negative electrode plate: the first nanofiltration membrane, the second nanofiltration membrane, the bipolar membrane and the first nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate of the first nanofiltration membrane are replaced by negative membranes;

or when the membrane stack I-4-1 is sequentially provided with an anode membrane, a bipolar membrane, a nanofiltration membrane, a cathode membrane and an anode membrane from an electrode positive plate to an electrode negative plate: the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate in the positive membrane, the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane are replaced by the nanofiltration membrane;

or when the membrane stack I-4-2 is sequentially provided with a negative membrane, a positive membrane, a bipolar membrane, a nanofiltration membrane and a negative membrane from an electrode positive plate to an electrode negative plate: the negative membrane, the positive membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane which is close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane;

Or when the membrane stack I-4-3 is sequentially provided with a nanofiltration membrane, a negative membrane, a positive membrane, a bipolar membrane and a nanofiltration membrane from the positive electrode plate to the negative electrode plate: the nanofiltration membrane, the negative membrane, the positive membrane, the bipolar membrane and the nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate of the nanofiltration membrane are replaced by the negative membrane;

or when the membrane stack I-5-1 is sequentially provided with a nanofiltration membrane, a bipolar membrane, a negative membrane, a positive membrane and a nanofiltration membrane from an electrode positive plate to an electrode negative plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane is replaced by the positive membrane;

or when the membrane stack I-5-2 is sequentially provided with an anode membrane, a nanofiltration membrane, a bipolar membrane, a cathode membrane and an anode membrane from an electrode positive plate to an electrode negative plate: the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate in the positive membrane, the nanofiltration membrane, the bipolar membrane, the negative membrane and the positive membrane are replaced by the nanofiltration membrane;

or when the membrane stack I-5-3 is sequentially provided with a negative membrane, a positive membrane, a nanofiltration membrane, a bipolar membrane and a negative membrane from an electrode positive plate to an electrode negative plate: the negative membrane, the positive membrane, the nanofiltration membrane, the bipolar membrane and the negative membrane which is close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane;

Or when the membrane stack I-6-1 is sequentially provided with a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, a negative membrane, a positive membrane and a second nanofiltration membrane from an electrode positive plate to an electrode negative plate: the second nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate in the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane is replaced by the positive membrane;

or when the membrane stack I-6-2 is sequentially provided with an anode membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane, a cathode membrane and an anode membrane from an electrode positive plate to an electrode negative plate: the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate in the positive membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane, the negative membrane and the positive membrane are replaced by nanofiltration membranes;

or when the membrane stack I-6-3 is sequentially provided with a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane, a first nanofiltration membrane and a negative membrane from an electrode positive plate to an electrode negative plate: the negative membrane, the positive membrane, the second nanofiltration membrane, the bipolar membrane, the first nanofiltration membrane and the negative membrane which is close to the positive electrode plate and/or close to the negative electrode plate in the negative membrane are replaced by nanofiltration membranes;

Or when the membrane stack I-6-4 is sequentially provided with a first nanofiltration membrane, a negative membrane, a positive membrane, a second nanofiltration membrane, a bipolar membrane and a first nanofiltration membrane from an electrode positive plate to an electrode negative plate: the first nanofiltration membrane, the negative membrane, the positive membrane, the second nanofiltration membrane, the bipolar membrane and the first nanofiltration membrane which is close to the positive electrode plate and/or the negative electrode plate of the first nanofiltration membrane are replaced by the negative membrane;

or when the membrane stack II-1-1 is provided with a nanofiltration membrane, a bipolar membrane and a nanofiltration membrane in sequence from the positive electrode plate to the negative electrode plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is replaced by an anode membrane;

or when the membrane stack II-2-1 is provided with a nanofiltration membrane, a bipolar membrane and a nanofiltration membrane in sequence from the positive electrode plate to the negative electrode plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane and the nanofiltration membrane is replaced by a negative membrane;

or when the membrane stack II-3-1 is provided with a nanofiltration membrane, a bipolar membrane, an anode membrane and a nanofiltration membrane in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the bipolar membrane, the positive membrane and the nanofiltration membrane is replaced by the positive membrane;

Or when the membrane stack II-3-2 is sequentially provided with an anode membrane, a nanofiltration membrane, a bipolar membrane and an anode membrane from the electrode positive plate to the electrode negative plate: the positive membrane, the nanofiltration membrane, the bipolar membrane and the positive membrane close to the positive electrode plate and/or the negative electrode plate in the positive membrane are replaced by the nanofiltration membrane;

or when the negative membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane are sequentially arranged in the direction from the positive electrode plate to the negative electrode plate of the membrane stack II-4-1: the negative membrane, the bipolar membrane, the nanofiltration membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane;

or when the nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane are sequentially arranged in the direction from the positive electrode plate to the negative electrode plate of the membrane stack II-4-2: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane, the bipolar membrane and the nanofiltration membrane are replaced by the negative membrane;

or when the membrane stack III-1-1 is sequentially provided with an anode membrane, a nanofiltration membrane and an anode membrane from the electrode positive plate to the electrode negative plate: the positive membrane, the nanofiltration membrane and the positive membrane close to the positive electrode plate and/or the negative electrode plate of the positive membrane are replaced by the nanofiltration membrane;

Or when the membrane stack III-1-2 is provided with a nanofiltration membrane, an anode membrane and a nanofiltration membrane in sequence from the electrode positive plate to the electrode negative plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the positive membrane and the nanofiltration membrane is replaced by a negative membrane;

or when the membrane stack III-2-1 is provided with a negative membrane, a nanofiltration membrane and a negative membrane in sequence from the positive electrode plate to the negative electrode plate: the negative membrane, the nanofiltration membrane and the negative membrane close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by the nanofiltration membrane;

or when the membrane stack III-2-2 is sequentially provided with a nanofiltration membrane, a negative membrane and a nanofiltration membrane from the positive electrode plate to the negative electrode plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane and the nanofiltration membrane is replaced by a positive membrane;

or when the membrane stack III-3-1 is sequentially provided with a nanofiltration membrane, a negative membrane, a positive membrane and a nanofiltration membrane from the positive electrode plate to the negative electrode plate: the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane, the positive membrane and the nanofiltration membrane is replaced by a negative membrane; or the nanofiltration membrane close to the positive electrode plate and/or the nanofiltration membrane close to the negative electrode plate in the nanofiltration membrane, the negative membrane, the positive membrane and the nanofiltration membrane is replaced by the positive membrane;

Or when the membrane stack III-3-2 is sequentially provided with an anode membrane, a nanofiltration membrane, a cathode membrane and an anode membrane from an electrode positive plate to an electrode negative plate: the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate in the positive membrane, the nanofiltration membrane, the negative membrane and the positive membrane are replaced by the nanofiltration membrane;

or when the membrane stack III-3-3 is sequentially provided with a negative membrane, a positive membrane, a nanofiltration membrane and a negative membrane from the positive electrode plate to the negative electrode plate: the negative membrane close to the positive electrode plate and/or the negative membrane close to the negative electrode plate in the negative membrane, the positive membrane, the nanofiltration membrane and the negative membrane are replaced by the nanofiltration membrane;

or when the membrane stack III-4-1 is sequentially provided with a negative membrane, a positive membrane, a first nanofiltration membrane, a second nanofiltration membrane and a negative membrane from an electrode positive plate to an electrode negative plate: the negative membrane, the positive membrane, the first nanofiltration membrane, the second nanofiltration membrane and the negative membrane which is close to the positive electrode plate and/or the negative electrode plate in the negative membrane are replaced by nanofiltration membranes;

or when the membrane stack III-4-2 is sequentially provided with an anode membrane, a first nanofiltration membrane, a second nanofiltration membrane, a cathode membrane and an anode membrane from an electrode positive plate to an electrode negative plate: the positive membrane close to the positive electrode plate and/or the positive membrane close to the negative electrode plate in the positive membrane, the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane and the positive membrane are replaced by nanofiltration membranes;

Or when the membrane stack III-4-3 is sequentially provided with a first nanofiltration membrane, a second nanofiltration membrane, a negative membrane, a positive membrane and a first nanofiltration membrane from the positive electrode plate to the negative electrode plate: the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane, the positive membrane and the first nanofiltration membrane which is close to the positive electrode plate and/or the negative electrode plate of the first nanofiltration membrane are replaced by the positive membrane; or the first nanofiltration membrane, the second nanofiltration membrane, the negative membrane, the positive membrane and the first nanofiltration membrane which is close to the positive electrode plate and/or the negative electrode plate of the first nanofiltration membrane are replaced by the negative membrane;

or when the membrane stack III-4-4 is sequentially provided with a second nanofiltration membrane, a negative membrane, a positive membrane, a first nanofiltration membrane and a second nanofiltration membrane from the positive electrode plate to the negative electrode plate: the second nanofiltration membrane close to the positive electrode plate and/or the second nanofiltration membrane close to the negative electrode plate in the second nanofiltration membrane, the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane is replaced by the positive membrane; or the second nanofiltration membrane close to the positive electrode plate and/or the negative electrode plate in the second nanofiltration membrane, the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane is replaced by the negative membrane;

Or when the membrane stack I-1: when a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane, the first negative membrane and the first nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane;

or when the membrane stack I-1: when the negative membrane, the nanofiltration membrane are sequentially arranged between the electrode positive plate and the first bipolar membrane, the negative membrane and the nanofiltration membrane, and the bipolar membrane, the negative membrane and the nanofiltration membrane are sequentially arranged between the last bipolar membrane, the negative membrane and the nanofiltration membrane and the electrode negative plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

or when the membrane stack I-2: when an anode membrane is arranged between the electrode positive plate and the first combination of the bipolar membrane, the nanofiltration membrane and the anode membrane: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

or when the membrane stack I-2: the electrode positive plate and the first are nanofiltration membrane and positive membrane are arranged between the combination of the bipolar membrane, the nanofiltration membrane and the positive membrane in sequence, and the last is the combination of the bipolar membrane, the nanofiltration membrane and the positive membrane and the electrode negative plate are arranged between the bipolar membrane and the nanofiltration membrane in sequence: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with a negative membrane;

Or when the membrane stack I-3: when a second nanofiltration membrane is arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane: the second nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate is replaced by an anode membrane sheet;

or when the membrane stack I-3: when the combination of the electrode positive plate and the first bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane is arranged between the electrode positive plate and the combination of the bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane in sequence, and the combination of the last bipolar membrane, the first nanofiltration membrane and the second nanofiltration membrane and the combination of the electrode negative plate are arranged between the electrode positive plate and the electrode negative plate in sequence: the first nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate is replaced by a negative membrane sheet;

or when the membrane stack I-4: when an anode membrane is arranged between the electrode positive plate and the first combination of the bipolar membrane, the nanofiltration membrane, the cathode membrane and the anode membrane: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

or when the membrane stack I-4: when the negative membrane, the positive membrane and the last bipolar membrane, nanofiltration membrane, negative membrane and positive membrane are sequentially arranged between the positive electrode plate and the first bipolar membrane, nanofiltration membrane, negative membrane and positive membrane, and the bipolar membrane, nanofiltration membrane and negative membrane are sequentially arranged between the negative electrode plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

Or when the membrane stack I-4: the electrode positive plate and the first bipolar membrane, nanofiltration membrane, negative membrane and positive membrane are sequentially arranged between the combination of the electrode positive plate and the bipolar membrane, the nanofiltration membrane, the negative membrane and the positive membrane, and the last bipolar membrane, nanofiltration membrane, negative membrane and positive membrane and the electrode negative plate are sequentially arranged between the combination of the bipolar membrane and the nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with a negative membrane;

or when the membrane stack I-5: when a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane, the first negative membrane, the first positive membrane and the first nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane;

or when the membrane stack I-5: when the positive membrane and the nanofiltration membrane are sequentially arranged between the positive electrode plate and the first combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane, and the last combination of the bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane and the negative electrode plate are sequentially arranged between the negative electrode plate and the positive electrode plate: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

Or when the membrane stack I-5: when the negative membrane, the positive membrane and the nanofiltration membrane are sequentially arranged between the positive electrode plate and the first bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane, the last bipolar membrane, the negative membrane, the positive membrane and the nanofiltration membrane and the bipolar membrane and the negative electrode plate are sequentially arranged between the negative electrode plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

or when the membrane stack I-6: when a second nanofiltration membrane is arranged between the positive electrode plate and the combination of the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane: the second nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate is replaced by an anode membrane sheet;

or when the membrane stack I-6: the electrode positive plate and the first positive membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane are sequentially arranged between the combination of the positive plate and the negative plate, and the last positive membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane are sequentially arranged between the negative plate and the positive plate: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

Or when the membrane stack I-6: when the negative membrane, the positive membrane and the second nanofiltration membrane are sequentially arranged between the positive electrode plate and the first bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane, and the last bipolar membrane, the first nanofiltration membrane, the negative membrane, the positive membrane and the second nanofiltration membrane are sequentially arranged between the negative electrode plate and the bipolar membrane, the first nanofiltration membrane and the negative membrane: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

or when the membrane stack I-6: the electrode positive plate and the first are set gradually between the combination of bipolar diaphragm, first nanofiltration diaphragm, negative diaphragm, positive diaphragm, second nanofiltration diaphragm and are received and strained the diaphragm, are received and is received the diaphragm, the second between the combination of bipolar diaphragm, first nanofiltration diaphragm, negative diaphragm, positive diaphragm, second nanofiltration diaphragm and when being set gradually bipolar diaphragm, first nanofiltration diaphragm between the electrode negative plate: the first nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate is replaced by a negative membrane sheet;

or when the membrane stack II-1: when a nanofiltration membrane is arranged between the positive electrode plate and the first bipolar membrane and nanofiltration membrane combination: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane;

Or when the membrane stack II-2: when a nanofiltration membrane is arranged between the combination of the last nanofiltration membrane and the bipolar membrane and the negative electrode plate: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with a negative membrane;

or when the membrane stack II-3: when a nanofiltration membrane is arranged between the electrode positive plate and the first combination of the bipolar membrane, the positive membrane and the nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane;

or when the membrane stack II-3: when the positive electrode plate and the first positive membrane, the positive membrane and the nanofiltration membrane are sequentially arranged between the combination of the positive electrode plate and the negative electrode plate, the positive membrane and the nanofiltration membrane, and the last positive membrane, the negative membrane and the nanofiltration membrane are sequentially arranged between the combination of the positive electrode plate and the negative electrode plate: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

or when the membrane stack II-4: when a negative membrane is arranged between the last combination of the negative membrane, the bipolar membrane and the nanofiltration membrane and the negative electrode plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

Or when the membrane stack II-4: when a nanofiltration membrane is arranged between the positive electrode plate and the first negative membrane, the bipolar membrane and the nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with a negative membrane;

or when the membrane stack III-1: when an anode membrane is arranged between the positive electrode plate and the combination of the first nanofiltration membrane and the anode membrane: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

or when the membrane stack III-1: when a nanofiltration membrane is arranged between the combination of the last nanofiltration membrane and the anode membrane and the electrode negative plate: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with a negative membrane;

or when the membrane stack III-2: when a negative membrane is arranged between the last combination of the negative membrane and the nanofiltration membrane and the negative electrode plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

or when the membrane stack III-2: when a nanofiltration membrane is arranged between the positive electrode plate and the first combination of the negative membrane and the nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane;

Or when the membrane stack III-3: when a nanofiltration membrane is arranged between the positive electrode plate and the first negative membrane, the first positive membrane and the first nanofiltration membrane: replacing the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane; or the nanofiltration membrane close to the positive electrode plate and/or close to the negative electrode plate is replaced by a negative membrane;

or when the membrane stack III-3: the electrode positive plate and the first positive membrane, receive and filter and have set gradually positive membrane, receive and filter the membrane between the combination of membrane, positive membrane, receive and filter the membrane, the last negative membrane, positive membrane, receive and filter the combination of membrane and when having set gradually negative membrane, positive membrane between the electrode negative plate: replacing the positive membrane sheet close to the positive electrode plate and/or close to the negative electrode plate with a nanofiltration membrane sheet;

or when the membrane stack III-3: when a negative membrane is arranged between the last combination of the negative membrane, the positive membrane and the nanofiltration membrane and the negative electrode plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

or when the membrane stack III-4: when a negative membrane is arranged between the last combination of the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane and the negative electrode plate: replacing the negative membrane close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane;

Or when the membrane stack III-4: the positive electrode plate and the first negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane are sequentially arranged between the combination of the positive electrode plate and the negative electrode plate, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane, and the last negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane is sequentially arranged between the combination of the negative electrode plate and the negative electrode plate: replacing the positive membrane sheet close to the positive electrode plate and/or the negative electrode plate with a nanofiltration membrane sheet;

or when the membrane stack III-4: when the combination of the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane and the combination of the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane are sequentially arranged between the positive electrode plate and the negative electrode plate, the combination of the negative membrane, the positive membrane, the first nanofiltration membrane and the second nanofiltration membrane and the combination of the negative membrane, the positive membrane and the first nanofiltration membrane are sequentially arranged between the negative electrode plate: replacing the first nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate with an anode membrane sheet; or the first nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate is replaced by a negative membrane sheet;

Or when the membrane stack III-4: when a second nanofiltration membrane is arranged between the positive electrode plate and the combination of the first negative membrane, the first positive membrane, the first nanofiltration membrane and the second nanofiltration membrane: the second nanofiltration membrane sheet close to the positive electrode plate and/or close to the negative electrode plate is replaced by an anode membrane sheet; or the second nanofiltration membrane sheet adjacent to the positive electrode plate and/or adjacent to the negative electrode plate is replaced by a negative membrane sheet.

7. An electrodialysis apparatus or bipolar membrane apparatus comprising a stack of membranes according to any one of claims 1 to 6.

8. Electrodialysis apparatus or bipolar membrane apparatus according to claim 7,

the outlet of the water inlet chamber is connected to the inlet of the water inlet tank, the outlet of the water inlet tank is connected to the water inlet circulating pump, and the outlet of the water inlet circulating pump is connected to the inlet of the water inlet chamber to form circulation;

or the outlet of the concentration chamber is connected to the inlet of the concentration tank, the outlet of the concentration tank is connected to the concentration circulating pump, and the outlet of the concentration circulating pump is connected to the inlet of the concentration chamber to form circulation;

or the outlet of the first concentration chamber is connected to the inlet of the first concentration tank, the outlet of the first concentration tank is connected to the first concentration circulating pump, and the outlet of the first concentration circulating pump is connected to the inlet of the first concentration chamber to form circulation;

Or the outlet of the second concentration chamber is connected to the inlet of the second concentration tank, the outlet of the second concentration tank is connected to the second concentration circulating pump, and the outlet of the second concentration circulating pump is connected to the inlet of the second concentration chamber to form circulation;

or the outlet of the third concentration chamber is connected to the inlet of the third concentration tank, the outlet of the third concentration tank is connected to the third concentration circulating pump, and the outlet of the third concentration circulating pump is connected to the inlet of the third concentration chamber to form circulation;

or the outlet of the acid chamber is connected to the inlet of the acid tank, the outlet of the acid tank is connected to the acid circulating pump, and the outlet of the acid circulating pump is connected to the inlet of the acid chamber to form circulation;

or the outlet of the first acid chamber is connected to the inlet of the first acid tank, the outlet of the first acid tank is connected to the first acid circulating pump, and the outlet of the first acid circulating pump is connected to the inlet of the first acid chamber to form a circulation;

or the outlet of the second acid chamber is connected to the inlet of the second acid tank, the outlet of the second acid tank is connected to the second acid circulating pump, and the outlet of the second acid circulating pump is connected to the inlet of the second acid chamber to form circulation;

or the outlet of the alkali chamber is connected to the inlet of the alkali tank, the outlet of the alkali tank is connected to the alkali circulating pump, and the outlet of the alkali circulating pump is connected to the inlet of the alkali chamber to form circulation;

or the outlet of the first alkali chamber is connected to the inlet of the first alkali tank, the outlet of the first alkali tank is connected to the first alkali circulating pump, and the outlet of the first alkali circulating pump is connected to the inlet of the first alkali chamber to form circulation;

Or the outlet of the second alkali chamber is connected to the inlet of the second alkali tank, the outlet of the second alkali tank is connected to the second alkali circulating pump, and the outlet of the second alkali circulating pump is connected to the inlet of the second alkali chamber to form circulation;

or the outlet of the polar water chamber I is connected to the inlet of the polar water tank I, the outlet of the polar water tank I is connected to the polar water circulating pump I, and the outlet of the polar water circulating pump I is connected to the inlet of the polar water chamber I to form circulation; an outlet of the polar water chamber II is connected to an inlet of the polar water tank II, an outlet of the polar water tank II is connected to a polar water circulating pump II, and an outlet of the polar water circulating pump II is connected to an inlet of the polar water chamber II to form circulation;

or the outlet of the polar water chamber I and the outlet of the polar water chamber II are connected to the inlet of the polar water tank, the outlet of the polar water tank is connected to the polar water circulating pump, and the outlet of the polar water circulating pump is connected to the inlet of the polar water chamber I and the inlet of the polar water chamber II to form circulation.

9. Electrodialysis apparatus or bipolar membrane apparatus according to claim 8,

the concentration tank is provided with a water inlet pipe and a discharge port;

or the first concentration tank is provided with a water inlet pipe and a discharge port;

or the second concentration tank is provided with a water inlet pipe and a discharge port;

or the third concentration tank is provided with a water inlet pipe and a discharge port;

Or the acid tank is provided with a water inlet pipe and a discharge port;

or the first acid tank is provided with a water inlet pipe and a discharge port;

or the acid tank II is provided with a water inlet pipe and a discharge port;

or the alkali tank is provided with a water inlet pipe and a discharge port;

or the first alkali tank is provided with a water inlet pipe and a discharge port;

or the second alkali tank is provided with a water inlet pipe and a discharge port;

or the water inlet tank is provided with a water inlet pipe and a discharge port;

or the polar water tank I is provided with a water inlet pipe, and the polar water tank II is provided with a water inlet pipe;

or the polar water tank is provided with a water inlet pipe.

10. A water treatment system comprising an electrodialysis device or bipolar membrane device according to any one of claims 7 to 9.

11. The water treatment system of claim 10,

an aqueous solution supply pipe is connected to a water inlet pipe of a water inlet tank of the electrodialysis device;

or the water solution supply pipeline is connected to the water inlet pipe of the water inlet tank of the bipolar membrane device;

or the aqueous solution supply pipeline is connected to a water inlet pipe of a water inlet tank of the electrodialysis device, a discharge port of a concentration tank II or a discharge port of a concentration tank III of the electrodialysis device, a water inlet pipe of the water inlet tank of the bipolar membrane device or a water inlet of the bipolar membrane device';

Or the water solution supply pipeline is connected to the water inlet of the concentration unit, and the concentrated solution outlet of the concentration unit is connected to the water inlet pipe of the water inlet tank of the bipolar membrane device.

12. The water treatment system of claim 11, further comprising an alkali addition unit or a heating unit:

the outlet of the alkali adding unit is connected to the aqueous solution supply pipeline; or the aqueous solution supply pipeline is provided with an alkalization tank, and an outlet of the alkalization unit is connected to an inlet of the alkalization tank;

or a heating unit is provided on the aqueous solution supply pipe.

13. The water treatment system of claim 11, further comprising an acid addition unit:

or the outlet of the acid adding unit is connected to a pipeline between the concentrated solution outlet of the concentrating unit and the water inlet pipe of the water inlet tank of the bipolar membrane device; or an acidification tank is arranged on a pipeline between the concentrated solution outlet of the concentration unit and the water inlet pipe of the water inlet tank of the bipolar membrane equipment, and the outlet of the acidification unit is connected to the inlet of the acidification tank;

or the outlet of the acid adding unit is connected to a pipeline between the discharge outlet of the concentration tank, the discharge outlet of the concentration tank II or the discharge outlet of the concentration tank III of the electrodialysis device and the water inlet of the bipolar membrane device'; or an acidification tank is arranged on a pipeline between a discharge port of a concentration tank, a discharge port of the concentration tank, a discharge port of a second concentration tank or a discharge port of a third concentration tank of the electrodialysis equipment and a water inlet of the bipolar membrane equipment, and an outlet of an acid adding unit is connected to an inlet of the acidification tank.

14. The water treatment system of claim 11, 12 or 13, further provided with a tail gas absorption device,

The tail gas absorption device is connected to the aqueous solution supply line.

15. A water treatment system as claimed in claim 11, 12 or 13, further comprising hardness removing means for:

the hardness removing device is positioned in front of the water inlet of the electrodialysis device, the bipolar membrane device' or the concentration unit.