CN111954568B

CN111954568B - Saline water recovery system based on bipolar membrane

Info

Publication number: CN111954568B
Application number: CN201980010383.1A
Authority: CN
Inventors: 权秋红; 张建飞; 元西方; 赵庆
Original assignee: Bestter Group Co ltd
Current assignee: Bestter Group Co ltd
Priority date: 2018-10-17
Filing date: 2019-01-28
Publication date: 2022-04-15
Anticipated expiration: 2039-01-28
Also published as: WO2020077918A1; CN111954568A

Abstract

A bipolar membrane based brine recovery system comprising a first compartment (109), a second compartment (110) and a third compartment (111), wherein incoming water circulates in the form of electrode liquids in a third circulation path (8) defined by the first compartment (109), an anode compartment (203) of a primary electrodialyser (201) and a first intermediate water basin (3), and in a fourth circulation path (9) defined by the second compartment (110), a cathode compartment and the first intermediate water basin (3), respectively, wherein the first compartment (109) is configured in an operating mode for treating therewith a liquid in the third circulation path (8) and for treating therewith an acidic liquid formed, and the second compartment (110) is configured in an operating mode for treating therewith a liquid in the fourth circulation path (9) and for treating therewith a basic liquid formed, respectively.

Description

Saline water recovery system based on bipolar membrane

Technical Field

The invention belongs to the technical field of wastewater treatment devices, and particularly relates to a saline water recovery system based on a bipolar membrane.

Background

The bipolar membrane is an ion exchange membrane with special function, and the middle layer of the bipolar membrane is subjected to water dissociation under the action of an electric field to generate H⁺And OH^-Ions. The bipolar membrane electrodialysis technology is to combine the special function into common electrodialysis, so that the instant acid/alkali production/regeneration, or acidification and/or alkalization can be realized. The technique has been applied in inorganic processes, such as from NaCl, Na₂SO₄、KF、KNO₃、NH₄SO₄Salt solution or waste liquor to prepare corresponding acid and alkali. The bipolar membrane electrodialysis technology belongs to one of electrodialysis technologies, in the process of preparing acid or alkali by electrolysis of an aqueous solution containing halogen elements, halogen gas is inevitably generated at an anode, and under the condition that the generated gas is dissolved in water, the resistance and required voltage of the electrolytic solution are obviously increased, so that the energy consumption is increased. Meanwhile, the generated halogen gas is toxic gas, cannot be directly discharged outside, and a matched treatment device must be configured, so that the production cost is increased. When the electrode solution contains a halogen element, the pH of the anode chamber on the anode side tends to decrease, and the pH of the cathode chamber on the cathode side tends to increase. When the pH of the anode chamber decreases, chlorine gas is easily generated, and at this time, the pH of the electrode solution needs to be adjusted. The conventional method limits the type of the electrode solution used to adjust the pH by using an aqueous solution of sodium sulfate or an aqueous solution of sodium phosphate having a pH buffering function or an aqueous solution containing glycine and sodium hydroxide as the electrode solution, and the electrode solution generally needs to be supplied with a separate or added pH adjuster to control the pH thereof within a desired range.

Patent document No. CN107382737A discloses a method for preparing a bis-quaternary ammonium base, which comprises: the double quaternary ammonium salt is electrolyzed into double quaternary ammonium ions and corresponding anions by a bipolar membrane electrodialysis process, the bipolar membrane is simultaneously subjected to water dissociation to generate hydrogen ions and hydroxide ions, the double quaternary ammonium ions and the hydroxide ions are combined to generate double quaternary ammonium base under the action of an external electric field by utilizing the selective permeability of an ion exchange membrane, and the hydrogen ions and the anions generated by the electrolysis of the double quaternary ammonium salt are combined to generate acid. In the bipolar membrane electrodialysis process, no additional chemical substance is needed, and the acid liquor obtained in the process can be recycled and is environment-friendly. But the method has high energy consumption, poor quality of the obtained treated water and low desalination efficiency.

Meanwhile, in order to inhibit the scaling of the ion exchange membrane, the conventional operation is reverse polarity, namely in the running process of the electric desalting device, the polarity of the electrode of the device is periodically reversed, the original anode is changed into the cathode, the original cathode is changed into the anode, and the corresponding concentration chamber and the desalting chamber of the original electric desalting device are also reversed, so that the purposes of eliminating the concentration polarization of the membrane surface and inhibiting the scaling are achieved. However, the electrode inverting operation is not so called for the preparation of drinking water by brackish desalination or the preparation of pure water by tap water desalination, only some raw water is lost in the electrode inverting process, but raw material liquid is lost for organic material desalination, which is not allowed, so that the electrode inverting operation can be adopted only, the intermittent operation is adopted, the machine is stopped after one batch of desalination, and the system is subjected to acid washing, which inevitably brings negative effects of complex operation, unstable desalination performance, short service life of an ion exchange membrane and the like. Another conventional practice is to adjust the ion concentration of the recycled concentrate to a concentration level that reduces the concentration polarization and the potential for fouling.

Patent document CN101543730 discloses a system comprising an electrodialyzer, a stock solution storage tank and a desalting material storage tank, wherein the electrodialyzer comprises anion-cation exchange membranes alternately arranged between positive and negative electrodes, one side of the positive electrode is an anode chamber, one side of the negative electrode is a cathode chamber, desalting chambers and concentrating chambers are alternately formed between the anode chamber and the cathode chamber, the concentrating chambers and the anode chamber of the electrodialyzer are connected with a softened water tank, the other end of the anode chamber is communicated with one end of a softened water inlet of the concentrating chamber, and produced water of the desalting chambers is input into the desalting material storage tank. The cathode chamber, the concentration chamber and the anode chamber are all connected with an external softened water tank, softened water is input into the cathode chamber, the concentration chamber and the anode chamber, one part of fluid in the concentration chamber of the electrodialyzer is circularly supplied by concentrated solution, and the other part of fluid is supplied by the softened water tank, so that the scaling possibility is reduced, the structure is simple, and the operation is convenient. The outlet of the anode chamber is connected with a pipeline, the other end of the pipeline is connected with the inlet of the concentration chamber, and the circulating water in the anode chamber is input into the concentration chamber through the pipeline by utilizing the water pressure in the electrodialyzer to be used as a part of the fluid of the concentration chamber. The possibility of scaling is reduced by removing part of ions in the salt-containing wastewater in a manner of softening the wastewater, the ion exchange membrane does not fundamentally start from the ion exchange membrane, and the ion exchange membrane still has a large scaling risk.

Disclosure of Invention

In view of the deficiencies of the prior art, the present invention provides a brine recovery system based on bipolar membranes, comprising at least a bipolar membrane electrodialyzer located on the downstream side of a primary electrodialyzer. The bipolar membrane electrodialyzer is partitioned into at least a first compartment, a second compartment and a third compartment by at least three bipolar membranes in a direction along a line connecting an anode and a cathode of the bipolar membrane electrodialyzer. The fluid, upon entering the first intermediate reservoir, is treated according to at least the following steps: the fluid is desalted and desalted through a first circulation passage defined by the primary electrodialyzer and/or a second circulation passage defined by the primary electrodialyzer and the bipolar membrane electrodialyzer to obtain produced water. The fluid circulates in the form of an electrode liquid in a third circulation path defined by the first compartment, the anode compartment of the primary electrodialyser and the first intermediate water basin, and in a fourth circulation path defined by the second compartment, the cathode compartment of the primary electrodialyser and the first intermediate water basin, respectively, wherein the first compartment is configured in a working mode in which the fluid treated by it is able to neutralize, in the third circulation path, the fluid formed in acid by treatment of the anode compartment, and the second compartment is configured in a working mode in which the fluid treated by it is able to neutralize, in the fourth circulation path, the fluid formed in alkaline by treatment of the cathode compartment.

According to a preferred embodiment, the fluid in the first circulation path enters the fresh water chamber of the primary electrodialyzer in a manner of flowing in a first direction to perform desalination and desalination. The fluid in the second circulation path enters the concentrate chamber of the primary electrodialyzer in such a manner as to flow in a second direction for concentration treatment, wherein the first direction and the second direction are configured in parallel and opposite patterns to each other such that a concentration difference between the concentrate chamber and the dilute chamber is minimized within the same plane perpendicular to the first direction or the second direction.

According to a preferred embodiment, an anion exchange membrane and a cation exchange membrane are arranged between the two bipolar membranes, so that the bipolar membrane electrodialyzer takes the form of a first compartment, a third compartment, a fourth compartment, a fifth compartment, a sixth compartment and a second compartment in sequence in the direction from the anode to the cathode, wherein the fluid of the second circulation path is subjected to desalination treatment in the third direction in such a manner that the fluid flows through the concentrated water chamber, the third compartment and the fifth compartment in sequence to obtain the produced water. The produced water enters the fourth and sixth compartments in a fourth direction for treatment to obtain an acid product and a base product, respectively, wherein the third and fourth directions are parallel and opposite to each other.

According to a preferred embodiment, a pH sensor for monitoring the pH of the fluid is provided in the first intermediate water tank, wherein, when the fluid of the third circulation path and the fourth circulation path flows back to the first intermediate water tank, the acid product or the alkali product can flow back to the first intermediate water tank to adjust the pH of the fluid when the pH monitored by the pH sensor is out of a set range.

According to a preferred embodiment, the brine recovery system further comprises a water quality monitor arranged in the second intermediate water basin, wherein the water quality monitor is configured in an operation mode capable of monitoring at least chloride ion concentration, heavy metal ion concentration and/or suspended matter content. And the fluid in the second intermediate water tank is circularly treated in a mode of following the first circulation path and/or the second circulation path until the effluent index of the fluid meets the preset standard of the water quality monitor.

According to a preferred embodiment, a liquid level monitor is provided in the second intermediate reservoir. Under the circumstances that the liquid level monitor monitored the liquid level of fluid in the middle pond of second and was less than first preset height, the pond is according to with the mode that first middle pond switched on is supplemented to the pond in the middle of the second fluid, cuts off under the circumstances that the liquid level of pond fluid is greater than second preset height in the middle of the second first middle pond with the intercommunication in the middle of the pond of second, wherein, first middle pond with under the circumstances that the pond is not communicated in the middle of the second, fluid in the pond is according to following first circulation route and/or circulation processing is carried out to the mode of second circulation route until the play water index of fluid satisfies the predetermined standard of water quality monitor.

The present invention also provides a scale-inhibiting brine recovery system comprising at least the primary electrodialyzer and the bipolar membrane electrodialyzer, wherein the bipolar membrane electrodialyzer is configured to: the fluid treated by the first compartment is capable of neutralizing in the third circulation path the fluid formed by treatment of the anodic compartment in an acid mode of operation, and the second compartment is configured in the fourth circulation path to neutralize in the fourth circulation path the fluid formed by treatment of the cathodic compartment in an alkaline mode of operation. The primary electrodialyser is configured to: fluid enters the concentrate and dilute chambers, respectively, with a pressure differential, wherein the anion exchange membrane and/or the cation exchange membrane between adjacent concentrate and dilute chambers can be offset a first distance in a first direction parallel to the line connecting the cathode and the anode based on the pressure differential to form a first operating configuration. The ion exchange membrane is further capable of being shifted a second distance in a second direction parallel to a line connecting the cathode and the anode based on a change in the pressure difference to form a second operating configuration, wherein switching between the first operating configuration and the second operating configuration is achieved in the event that the conductivity of the concentrate chamber and/or the conductivity of the dilute chamber is above a set threshold.

According to a preferred embodiment, the ion exchange membranes delimiting the dilute chambers are displaced in a deviating manner in the first and second direction, respectively, to form a first width from each other and in an opposing manner in the first and second direction, respectively, in the presence of a positive pressure difference between the dilute chambers and the concentrate chambers, and the ion exchange membranes delimiting the concentrate chambers are displaced in the opposing manner in the first and second direction, respectively, to form a second width from each other, wherein the first operating configuration is defined by the first and second widths.

According to a preferred embodiment, the ion exchange membranes delimiting the concentrate chambers are displaced in a deviating manner in the first and second direction, respectively, to form a fourth width from each other in the case of a negative pressure difference between the dilute and concentrate chambers, and the ion exchange membranes delimiting the dilute chambers are displaced in an opposing manner in the first and second direction, respectively, to form a third width from each other, wherein the second operating configuration is defined by the fourth and third widths.

The present invention also provides a brine recovery system capable of automatically cleaning an ion exchange membrane, using at least a primary electrodialyzer and a bipolar membrane electrodialyzer of one of the preceding claims, wherein a fluid is capable of entering the primary electrodialyzer and/or the bipolar membrane electrodialyzer in such a way that the direction of flow thereof is perpendicular to the filtration and permeation direction of the ion exchange membrane, wherein the primary electrodialyzer and the bipolar membrane electrodialyzer each have disposed therein a number of bio-inert particle balls having a density less than the density of the fluid, the bio-inert particle balls being configured to: the fluid drives the primary electrodialyzer to move from the water inlet to the water outlet in a sinking mode, and the fluid drives the primary electrodialyzer to move from the water outlet to the water inlet in a floating mode based on buoyancy. Or the fluid drives the bipolar membrane electrodialyzer to move from the water inlet of the bipolar membrane electrodialyzer to the water outlet of the bipolar membrane electrodialyzer in a sinking mode, and drives the bipolar membrane electrodialyzer to move from the water outlet of the bipolar membrane electrodialyzer to the water inlet of the bipolar membrane electrodialyzer in a floating mode based on buoyancy.

According to a preferred embodiment, the brine recovery system further comprises a waste water reduction unit configured to: obtaining at least a first concentration of concentrated brine and a second concentration of concentrated brine having different salt contents from each other based on a first reverse osmosis unit, a second reverse osmosis unit, and/or a combination thereof, the fluids including at least the first concentration of concentrated brine and the second concentration of concentrated brine, wherein the fluids are capable of entering the primary electrodialyzer at least with different flow rates and/or different densities such that there is a pressure difference between adjacent concentrated and dilute chambers thereof, wherein, in case at least two ion exchange membranes defining a concentrated or dilute chamber move in an opposite manner to form a minimum distance based on the pressure difference, the fluid entering the respective reaction chamber has a greater density than the fluid in the reaction chamber adjacent thereto such that bio-inert particle balls therein float at a greater velocity.

According to a preferred embodiment, the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer located on the downstream side thereof each have at least one third compartment, wherein the third compartment and the first compartment are adjacent to each other, and the fluid treated in the concentrate chamber in the second circulation path flows through the third compartment and the fifth compartment in sequence in such a manner as to first enter the second bipolar membrane electrodialyzer for desalination and desalination.

According to a preferred embodiment, the brine recovery system further comprises a water softening module, an oxidation treatment module and a pretreatment module, raw water is treated in a manner of sequentially flowing through the water softening module, the oxidation treatment module and the pretreatment module to obtain the fluid entering the first intermediate water tank, wherein the raw water is softened and filtered by the water softening treatment module in a manner of sequentially flowing through the homogenizing tank, the coagulation tank, the flocculation tank, the sedimentation tank and the sand filter tank to obtain the first treatment liquid.

According to a preferred embodiment, the second oxidation treatment module comprises at least an ozone generator for producing ozone and an ozone contact tank for carrying out an oxidation reaction, wherein the first treatment liquid is subjected to oxidation treatment in such a way that it is passed into the ozone contact tank simultaneously with the ozone to obtain the second treatment liquid.

According to a preferred embodiment, the second pretreatment module at least comprises an ultrafiltration membrane device, a cartridge filter and a reverse osmosis device, wherein the second treatment liquid is filtered by the ultrafiltration membrane device and the cartridge filter in sequence and then subjected to reverse osmosis concentration treatment by the reverse osmosis device to obtain the fluid.

The invention has the beneficial technical effects that:

(1) the invention is provided with a primary electrodialyzer and a bipolar membrane electrodialyzer, wherein electrode liquids of the primary electrodialyzer and the bipolar membrane electrodialyzer are concentrated brine obtained by processing by upstream equipment, a bipolar membrane on one side of the bipolar membrane electrodialyzer close to an anode chamber is configured into a working mode for generating hydroxide ions with higher efficiency, a bipolar membrane on the side of the bipolar membrane electrodialyzer close to a cathode chamber is configured into a working mode for generating hydrogen ions with higher efficiency, and the electrode liquids in the bipolar membrane electrodialyzer can be neutralized with weakly acidic or weakly alkaline electrode liquids generated by the primary electrodialyzer in a circulation process, so that the pH of the electrodes can be kept in an ideal range level all the time. Meanwhile, the degree of gas generation of the electrode chambers based on oxidation reduction can be effectively reduced by controlling the pH of the electrode liquid, the increasing trend of the resistance of the electrode liquid can be reduced, and the unit energy consumption of the electrodialyzer can be further reduced.

(2) The invention can eliminate the scaling substances accumulated on the ion exchange membrane in time by dynamically adjusting the form of the ion exchange membrane, can eliminate the scaling substances accumulated when the distance between the ion membranes of the concentrated water chamber or the fresh water chamber is smaller by increasing the distance between the ion membranes of the concentrated water chamber or the fresh water chamber, and can effectively inhibit the scaling of the ion exchange membrane. Meanwhile, when the form of the filtering membrane changes, the filtering membrane is mechanically scraped based on the biological inert particle balls, so that the scaling period of the filtering membrane can be effectively reduced.

Drawings

FIG. 1 is a schematic view of the modular connection relationship of a preferred bipolar membrane process module of the present invention;

FIG. 2 is a schematic view of the structure of a bipolar membrane electrodialyzer preferred in the present invention;

FIG. 3 is a schematic view of the modular connection relationship of another preferred bipolar membrane treatment module of the present invention;

FIG. 4 is a schematic view of the modular connections of the preferred brine recovery system of the present invention;

FIG. 5 is a schematic diagram showing the connection of the electronic modules of the preferred brine recovery system of the present invention;

FIG. 6 is the operating configuration of the ion-exchange membrane of the preferred primary electrodialyser of the invention;

FIG. 7 is another operating configuration of the ion-exchange membrane of the preferred primary electrodialyser of the invention; and

fig. 8 is a schematic diagram of the working principle of the preferred bio-inert particle balls of the present invention.

List of reference numerals

1: bipolar membrane treatment module 2: electrodialysis treatment module 3: first intermediate pool

4: second intermediate pool 5: the control valve 6: first circulation path

7: second circulation path 8: third circulation path 9: the fourth circulation path

10: third intermediate pool 11: fourth intermediate pool 12: water quality monitor

13: liquid level monitor 14: pH value sensor 15: water softening module

16: oxidation treatment module 17: the preprocessing module 18: medicine adding module

19: the control module 20: bio-inert particle ball 21: water inlet

22: water outlet 23: first reverse osmosis device 24: second reverse osmosis device

101: first bipolar membrane electrodialyzer 102: the second bipolar membrane electrodialyzer 103: pole frame

104: anode 105: cathode 106: bipolar membrane

107: anion exchange membrane 108: cation exchange membrane 109: the first compartment

110: the second compartment 111: third compartment 112: the fourth compartment

113: fifth compartment 114: sixth compartment 201: primary electrodialyser

202: cathode chamber 203: anode chamber 204: fresh water chamber

205: the concentrated water chamber 301: the homogenizing tank 302: coagulation tank

303: a flocculation tank 304: the sedimentation tank 305: sand filter

401: the air compressor 402: the ozone generator 403: tail gas destructor

404: ozone contact cell 405: oxygen generator 406: cold drying machine

407: the suction dryer 501: ultrafiltration membrane apparatus 502: safety filter

503: reverse osmosis unit 801: the first water supply pipe 802: a first water discharge pipe

901: the second water supply pipe 902: a second water supply pipe

D₁: first width D₂: second width D₃: third width

D₄: fourth width

Detailed Description

The following detailed description is made with reference to the accompanying drawings.

To facilitate understanding, identical reference numerals have been used, where possible, to designate similar elements that are common to the figures.

As used throughout this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words "include", "including", and "includes" mean including, but not limited to.

The phrases "at least one," "one or more," and/or "are open-ended expressions that encompass both association and disassociation in operation. For example, each of the expressions "at least one of A, B and C", "at least one of A, B or C", "one or more of A, B and C", "A, B or C" and "A, B and/or C" refers to a alone a, a alone B, a alone C, A and B together, a and C together, B and C together, or A, B and C together, respectively.

The terms "a" or "an" entity refer to one or more of that entity. As such, the terms "a" (or "an"), "one or more," and "at least one" are used interchangeably herein. It should also be noted that the terms "comprising," "including," and "having" may be used interchangeably.

As used herein, the term "automated" and variations thereof refer to any process or operation that is completed without substantial manual input when the process or operation is performed. However, if the input is received before the process or operation is performed, the process or operation may be automatic, even if the process or operation is performed using substantial or insubstantial manual input. Such manual input is considered to be material if such input affects the manner in which the process or operation is performed. Manual input that grants permission to perform the procedure or operation is not considered "material".

Example 1

The invention provides a saline water recovery system based on a bipolar membrane, which at least comprises a bipolar membrane treatment module 1. The bipolar membrane treatment module is used for treating the aqueous solution entering the bipolar membrane treatment module in an electrodialysis mode to obtain an acid solution, an alkali solution and a concentrated salt aqueous solution. The bipolar membrane treatment module comprises at least one bipolar membrane electrodialyzer. Fig. 2 shows a schematic view of a preferred structure of a bipolar membrane electrodialyzer, as shown in fig. 2, comprising at least a polar frame 103, an anode 104, a cathode 105, at least three bipolar membranes 106, at least one anion exchange membrane 107 and at least one cation exchange membrane 108, wherein the anode and the cathode are fixed at left and right ends of the polar frame in such a manner as to face each other. On the side close to the anode, two bipolar membranes are arranged in a side-by-side manner to form in sequence a first compartment 109 and a second compartment 110 in a direction along the anode towards the cathode. And the bipolar membrane closest to the anode side is provided with a cation exchange membrane at the side close to the first compartment and an anion exchange membrane at the side close to the second compartment, so that hydrogen ions generated by the bipolar membrane can enter the first compartment to reduce the pH increase of the bipolar membrane. The side of the other bipolar membrane slightly remote from the anode in contact with the second compartment is a cation exchange membrane, so that the second compartment is capable of receiving hydrogen ions and hydroxide ions from the two bipolar membranes, respectively.

Referring again to fig. 2, at least one bipolar membrane is provided on the side close to the cathode to form at least one third compartment 111, wherein the side of the bipolar membrane in contact with the third compartment is a cation exchange membrane, such that hydrogen ions generated by ionization of the bipolar membrane can enter the third compartment. The first compartment on the anode side is the anode compartment and the third compartment on the cathode side is the cathode compartment, and during the preparation of acids and bases by means of a bipolar membrane electrodialyzer, the pH of the anode compartment tends to decrease and the pH of the cathode compartment tends to increase. When the pH in the anode chamber is lowered to a predetermined threshold value, the amount of halogen gas such as chlorine gas generated at the anode is significantly increased. Leading to the need to avoid a continuous drop or increase in pH by, for example, switching the cathode and anode. The invention arranges corresponding bipolar membranes on the cathode side and the anode side, so that hydroxide ions are generated on the anode side to prevent the pH value of the anode chamber from decreasing, and hydrogen ions are generated on the cathode side to prevent the pH value of the cathode chamber from increasing.

Preferably, at least one anion exchange membrane and at least one cation exchange membrane are further arranged in the region between the second compartment and the third compartment, wherein in the direction pointing along the anode towards the cathode, the anion exchange membrane and the cation exchange membrane are arranged in sequence to define a fourth compartment 112, a fifth compartment 113 and a sixth compartment 114. The compartment between the second and third compartments is arranged in the manner of a three-compartment bipolar membrane cell, i.e. the fourth compartment is the acid compartment, the fifth compartment is the desalination compartment and the sixth compartment is the base compartment. The third compartment is used for recovering halogen ions such as chloride ions from the acid chamber on the adjacent side of the third compartment, so that the chloride ions are subjected to desalination treatment in the subsequent desalination and desalination chambers, and chlorine gas can be effectively prevented from being generated in the acid chamber and the anode chamber by the chloride ions. Compared with the flow mode that the fluid sequentially passes through the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyser, the fluid can better recover chloride ions in the acid chamber of the second bipolar membrane electrodialyser on the downstream side, so that the quality of desalted water in the desalting chamber of the second bipolar membrane electrodialyser can be improved, the continuous increase of the concentration of the chloride ions in the acid chamber and the anode chamber under the condition that the fluid is used as an electrode liquid is effectively inhibited, the quality degradation caused by the chloride ions is avoided, and the quality stability of the effluent is ensured.

Preferably, as shown in fig. 1, the bipolar membrane treatment module comprises at least a first bipolar membrane electrodialyzer 101 and a second bipolar membrane electrodialysis 102, and at least one electrodialysis treatment module 2 is further disposed upstream of the bipolar membrane treatment module, wherein the electrodialysis treatment module comprises at least a primary electrodialyzer 201. The primary electrodialyzer 201 is defined by at least two anion exchange membranes and at least two cation exchange membranes disposed between the anode and the cathode thereof to have a cathode compartment 202, an anode compartment 203, a fresh water compartment 204, and a concentrated water compartment 205. For example, in the direction pointing towards the cathode along the anode of the primary electrodialyser, are arranged in succession an anion exchange membrane, a cation exchange membrane, an anion exchange membrane and a cation exchange membrane. Preferably, the structure of the first and second bipolar membrane electrodialysers can be identical, or can be designed in a pattern with a different number of compartments from each other, depending on the actual situation. The first bipolar membrane electrodialyzer is arranged at the downstream of the second bipolar membrane electrodialyzer to further perform concentration treatment on the concentrated salt solution obtained by the treatment of the first bipolar membrane electrodialyzer, and the equipment cost can be reasonably reduced under the condition of ensuring the water treatment quality by arranging the two stages of bipolar membrane electrodialyzers.

Preferably, a first intermediate water tank 3 is arranged at the upstream of the electrodialysis treatment module, and a second intermediate water tank 4 is arranged at the downstream of the electrodialysis treatment module, wherein the first intermediate water tank is used for temporarily storing the concentrated salt solution generated after treatment by the upstream equipment, and the second intermediate water tank is used for temporarily storing the fresh water subjected to desalination by the electrodialysis treatment module.

Referring again to fig. 1, the first intermediate reservoir and the second intermediate reservoir are communicated through a pipeline so that the concentrated salt solution in the first intermediate reservoir can enter the second intermediate reservoir through the pipeline, wherein a control valve 5 is arranged on the pipeline communicating the first intermediate reservoir and the second intermediate reservoir to control the pipeline to be capable of performing a closing operation under the condition that the pipeline needs to be closed. The second middle water pool is provided with at least two water outlet pipes which are respectively communicated with the concentrated water chamber and the fresh water chamber of the primary electrodialyzer, wherein the water outlet of the fresh water chamber is communicated with the first middle water pool through a pipeline, so that fresh water in the fresh water chamber can flow back to the first middle water pool and then can be input into the fresh water chamber for multiple times to be subjected to multi-stage treatment to obtain the fresh water with lower salt content. The water outlet of the concentrated water chamber is communicated with the water inlet of the second compartment of the second bipolar membrane electrodialyzer through a pipeline, the water outlet of the second compartment of the second bipolar membrane electrodialyzer is communicated with the water inlet of the second compartment of the first bipolar membrane electrodialyzer, the water outlet of the second compartment of the first bipolar membrane electrodialyzer is communicated with the water inlet of the fifth compartment of the first bipolar membrane electrodialyzer, and the water outlet of the fifth compartment of the first bipolar membrane electrodialyzer is communicated with the fifth compartment of the second bipolar membrane electrodialyzer. The water outlet of the fifth compartment of the second bipolar membrane electrodialyzer is communicated with the second intermediate water tank through a pipeline. The water outlet of the first middle water tank is also respectively communicated with the water inlet of the anode chamber from which the first bipolar membrane electrodialysis, the second bipolar membrane electrodialyzer and the primary electrodialyzer are fed through pipelines, and the water outlet of the anode chamber from which the first bipolar membrane electrodialysis, the second bipolar membrane electrodialyzer and the primary electrodialyzer are fed through pipelines is communicated with the first middle water tank. The water outlet of the first intermediate water tank is also communicated with the water inlet of the cathode chamber from which the first bipolar membrane electrodialysis, the second bipolar membrane electrodialyzer and the primary electrodialyzer are fed through pipelines respectively, wherein the water outlet of the cathode chamber from which the first bipolar membrane electrodialysis, the second bipolar membrane electrodialyzer and the primary electrodialyzer are fed is communicated with the first intermediate water tank through a pipeline.

For ease of understanding, the water treatment flow of the bipolar membrane treatment module and the electrodialysis treatment module are discussed in detail.

After the treatment liquid obtained by the treatment of the equipment at the upstream of the bipolar membrane treatment module is transferred to the first intermediate water tank, the control valve on the pipeline for communicating the first intermediate water tank and the second intermediate water tank with each other is opened, and the treatment liquid in the first intermediate water tank can be conveyed to the second intermediate water tank through a lifting pump, for example. The second intermediate water tank is provided with a liquid level monitor, for example, and the control valve is closed to stop the continuous filling of the second intermediate water tank with the treatment liquid when the liquid level monitor monitors that the liquid level in the second intermediate water tank reaches a set value. The second intermediate water tank has two chambers, left and right, and the treatment liquid can be supplied to the first chamber located on the left side, for example.

After the control valve of the second intermediate water tank is closed, the treatment liquid in the first chamber on the left side in the second intermediate water tank can be circulated between the electrodialysis treatment module and the second chamber on the right side in the second intermediate water tank in such a manner that the first circulation path 6 is formed. Specifically, the treatment liquid in the first chamber enters a fresh water chamber of the primary electrodialyzer through a pipeline, and fresh water subjected to desalination and desalination in the fresh water chamber can be transmitted to the second chamber through the pipeline for temporary storage. The treatment liquid in the first chamber can also be conveyed to a concentrated water chamber of the primary electrodialyzer through a pipeline, and the treatment liquid is further concentrated in the concentrated water chamber and then conveyed to a bipolar membrane treatment module located at the downstream of the concentrated water chamber for further treatment. Preferably, the processing liquid enters the concentrate chamber with a flow direction in a first direction, and simultaneously enters the dilute chamber with a flow direction in a second direction, wherein the first direction and the second direction are opposite directions parallel to each other. For example, as shown in fig. 1, the flow direction of the treatment liquid in the concentrate chamber is from right to left, and the flow direction of the treatment liquid in the dilute chamber is from left to right. In the process of flowing the processing liquid in the concentrated water chamber, ions ionized in the fresh water chamber enter the concentrated water chamber, and a concentration trend of gradually increasing ion concentration is formed along the flowing direction of the processing liquid, namely, the concentration of the processing liquid at the right side of the concentrated water chamber is lower than that of the processing liquid at the left side of the concentrated water chamber. Similarly, the concentration of the solution on the inlet side of the dilute chamber will be higher than the concentration of the solution on the outlet side along the direction of flow of the process fluid in the dilute chamber. In the case where the first direction and the second direction are opposite, taking the right side of the primary electrodialyzer as an example, the portion corresponds to the outlet side of the fresh water chamber, the ion concentration of the solution on the outlet side of the fresh water chamber is smaller than that of the other portions of the fresh water chamber, the portion corresponds to the inlet side of the concentrate chamber, and the ion concentration of the solution on the inlet side of the concentrate chamber is also smaller than that of the other portions of the concentrate chamber, so that the concentration difference between the concentrate chamber and the fresh water chamber is minimized on the same plane perpendicular to the first direction or the second direction, the amount of water molecules in the fresh water chamber diffusing into the concentrate chamber due to the concentration difference can be reduced, and the water production efficiency of the primary electrodialyzer can be effectively improved. When the liquid level monitor detects that the liquid level in the first chamber is lower than a set threshold, a control valve between the first intermediate water tank and the second intermediate water tank is opened to replenish the new processing liquid. Similarly, in the case of the first direction and the second direction being opposite, taking the right side of the primary electrodialyzer as an example, during the desalination process, the fluid in the dilute chamber is stripped of ions so that the conductivity of the fluid tends to decrease, the fluid in the concentrate chamber tends to increase gradually due to the ions obtained from the adjacent dilute chamber, and the first direction and the second direction being opposite, the conductivity between the adjacent compartments can be in the same plane perpendicular to the first direction or the second direction, and the difference between the conductivity of the concentrate chamber and the conductivity of the dilute chamber is smaller. Smaller differences in conductivity can avoid polarization and excessive water splitting, and can effectively control the generation of scale.

The processing liquid in the first chamber on the left side of the second intermediate reservoir can be circulated and communicated with the second intermediate reservoir in such a manner as to form a second circulation path 7. Specifically, the treatment liquid in the first chamber enters a concentrated water chamber through a pipeline for concentration treatment to obtain a concentrated liquid, the concentrated liquid is sequentially conveyed to a second compartment of a second bipolar membrane electrodialyzer and a second compartment of a first bipolar membrane electrodialyzer through the pipeline, and the concentrated liquid after being treated by the second compartment of the first bipolar membrane electrodialyzer is conveyed to a fifth compartment of the first bipolar membrane electrodialyzer for first-stage desalination treatment to obtain a first-stage desalinated liquid. The first stage desalting liquid is conveyed to a fifth compartment of the first bipolar membrane electrodialyzer through a pipeline to be subjected to second stage desalting treatment to obtain second stage desalting liquid. And conveying the second-stage desalting solution to a second chamber of a second intermediate water pool through a pipeline for temporary storage.

The first intermediate water tank also supplies the required electrode liquid to the anode chamber and the cathode chamber of the bipolar membrane treatment module and the electrodialysis treatment module respectively through a third circulation path 8 and a fourth circulation path 9. Specifically, the third circulation path at least includes a first water supply pipe 801 and a first water discharge pipe 802, the first water supply pipe is directly communicated with the first intermediate water tank, water inlets of the anode chambers of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are respectively connected to the first water supply pipe through pipes, water outlets of the anode chambers of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are respectively communicated with the first water discharge pipe through pipes, and the first water discharge pipe is directly connected to the first intermediate water tank. The fourth circulation path includes at least a second water supply pipe 901 and a second water discharge pipe 902, the second water supply pipe is directly communicated with the first intermediate water tank, water inlets of the cathode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are respectively connected to the second water supply pipe through pipes, water outlets of the cathode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are respectively communicated with the second water discharge pipe through pipes, wherein the second water discharge pipe is directly connected to the first intermediate water tank. Based on the characteristics of the anode and cathode chambers, an oxidation reaction occurs in the anode chamber to generate hydrogen ions, and a reduction reaction occurs in the cathode chamber to generate hydroxyl ions. The bipolar membranes of the first and second bipolar membrane electrodialysers near their respective anode chambers are configured in an operation mode to generate hydroxide ions with greater efficiency, so that in the anode chambers, a part of the hydroxide ions can be remained after neutralization reaction of the hydroxide ions and hydrogen ions to control the electrode fluid discharged from the anode chambers to be in a weakly alkaline state. The primary electrodialyzer has no bipolar membrane, and hydrogen ions generated by oxidation of the primary electrodialyzer cannot be neutralized, so that the electrode solution discharged from the anode chamber of the primary electrodialyzer is weakly acidic. Weakly alkaline electrode solution discharged from the anode chamber of the bipolar membrane electrodialyzer and weakly acidic electrode solution discharged from the anode chamber of the primary electrodialyzer can be subjected to neutralization reaction in the first water discharge pipe and flow back to the first intermediate water tank. The bipolar membranes of the first and second bipolar membrane electrodialysers adjacent to their respective cathode compartments are configured in an operation mode to produce hydrogen ions with greater efficiency, so that in the cathode compartments, the hydroxide ions and hydrogen ions are neutralized and reacted, and then the remaining hydrogen ions are used to control the electrode fluid discharged from the cathode compartments to be in a weakly alkaline state. The primary electrodialyzer, without the bipolar membrane, cannot neutralize the hydroxide ions produced by its reduction, so that the electrode solution discharged from its cathode compartment is weakly alkaline. The weakly acidic electrode solution discharged from the cathode chamber of the bipolar membrane electrodialyzer and the weakly alkaline electrode solution discharged from the cathode chamber of the primary electrodialyzer can be subjected to neutralization reaction in the second water discharge pipe and flow back to the first intermediate water tank. The independent electrode liquid supply system is not separately arranged, the structural complexity of the bipolar membrane treatment module is reduced, and meanwhile, a neutralizing agent for keeping the pH value of the electrode liquid does not need to be additionally added, so that the cost of water treatment is reduced.

The fourth and sixth compartments of the first and second bipolar membrane electrodialysers are respectively an acid compartment and an alkali compartment through which the desired acid and alkali can be prepared, wherein, for example, fresh water, organic acid or inorganic acid can be prepared in such a manner that they enter the fourth compartment of the first and second bipolar membrane electrodialysers in sequence to prepare the corresponding acid product, which can be transferred to the third intermediate water basin 10 for temporary storage. For example fresh water or a low concentration of base, can be fed in sequence into the sixth compartment of the first bipolar membrane electrodialyser and into the sixth compartment of the second bipolar membrane electrodialyser to produce the corresponding base product, which can be transferred to the fourth intermediate water basin 11 for temporary storage. Preferably, the third intermediate water tank and the fourth intermediate water tank are also connected with the fourth compartment and the sixth compartment of the first bipolar membrane electrodialyzer respectively through pipes, and the concentrations of the acid product and the alkali product can be gradually increased by continuous circulation flow.

Preferably, the fourth intermediate water basin may be further connected to the respective first and second compartments of the first and second bipolar membrane electrodialysers, respectively, through pipes to adjust the pH thereof. A decrease in the pH of the first and second compartments can be avoided to some extent by adding the base product in the fourth intermediate water basin.

Example 2

This embodiment is a further improvement of embodiment 1, and repeated contents are not described again.

As shown in fig. 3, the second intermediate water tank has only one chamber, and a water quality monitor 12 is further disposed in the second intermediate water tank, wherein the water quality monitor may include a first ion detector for monitoring the concentration of chloride ions, a second ion detector for monitoring the concentration of heavy metal ions, and a micro-particle detector for monitoring the content of colloid and suspended matter, and in case that one of the water quality monitor indexes is not met, the fluid in the second intermediate water tank is subjected to a second circulation process through the first circulation path and the second circulation path. The predetermined standards for the water quality monitor can be set according to actual conditions, for example, when the fluid in the second intermediate water tank is used for industrial water or irrigation water, the metal ion concentration, the suspended matter content and the chloride ion concentration can be slightly higher than the standard of domestic water.

Preferably, a pH value sensor 14 for monitoring the pH value of the treatment liquid in the chamber of the first intermediate water tank is further arranged in the first intermediate water tank, wherein the first intermediate water tank is also communicated with the third intermediate water tank and the fourth intermediate water tank respectively through pipelines, and control valves are arranged on the pipelines communicated with each other so as to control the communication and disconnection of the first intermediate water tank and the third intermediate water tank and/or the fourth intermediate water tank. In the case where the pH sensor detects that the pH of the treatment liquid in the first intermediate tank exceeds the set range, the pH can be easily controlled within a desired range by opening the control valve to adjust the pH, for example, by introducing the alkaline product prepared in the fourth intermediate tank into the first intermediate tank when the pH of the treatment liquid in the first intermediate tank is detected to be too small.

Preferably, the desalted liquid treated by the fifth compartment of the second bipolar membrane electrodialyzer may be communicated with the fourth compartment and the fifth compartment of the first bipolar membrane electrodialyzer through pipes, respectively, wherein the fourth compartment of the first bipolar membrane electrodialyzer is connected with the fourth compartment of the second bipolar membrane electrodialyzer, and the sixth compartment of the first bipolar membrane electrodialyzer is connected with the sixth compartment of the second bipolar membrane electrodialyzer.

Example 3

This embodiment is a further improvement of the foregoing embodiment, and repeated contents are not described again.

As shown in fig. 4 and 5, the present invention provides a bipolar membrane-based brine recycling system, which is equipped with a bipolar membrane treatment module and an electrodialysis treatment module in the foregoing embodiments, wherein the brine recycling system further comprises a water softening module 15 for softening the fluid, an oxidation treatment module 16 for oxidizing the softened wastewater to eliminate harmful microorganisms such as bacteria in the wastewater, a pretreatment module 17, and a dosing module 18. The pretreatment module carries out primary concentration treatment on the wastewater according to a reverse osmosis treatment mode to obtain wastewater treatment liquid with certain salt content and concentration.

Preferably, the water softening module at least comprises a homogenizing tank 301, a coagulation tank 302, a flocculation tank 303, a sedimentation tank 304 and a sand filter 305, wherein the transfer flow of the wastewater among the homogenizing tank, the coagulation tank, the flocculation tank, the sedimentation tank and the sand filter can provide transfer driving force through a plurality of lifting pumps. The homogenizing tank is used for improving the non-uniformity of the components of the dispersed substances in the wastewater, and the wastewater can be subjected to relative motion in the homogenizing tank by stirring or ultrasonic vibration and the like to form a mixing and stirring effect. Preferably, the wastewater can be softened and pretreated by adding sodium hydroxide or sodium carbonate into the homogenizing tank, and preferably, the homogenizing tank is connected with the third intermediate water tank and the fourth intermediate water tank through pipelines, and the purpose of softening the wastewater can be achieved by adding acid or alkali. The coagulation tank is used for coagulation treatment of wastewater, and specifically, a large amount of flocculation clusters can be formed after the coagulant is fully mixed with the wastewater by adding the coagulant and combining with sufficient stirring. The flocculation tank is used for carrying out flocculation treatment on the wastewater, and particularly, a large amount of flocculation groups in the wastewater treated by the coagulation tank can generate large and compact alum flocs by adding a flocculating agent. The sedimentation tank is used for standing and settling the wastewater so as to enable large granular substances in the wastewater to sink to the bottom of the sedimentation tank, and then sludge is formed after uniform collection and is discharged from the original wastewater so as to achieve the purpose of purifying the water quality. The sand filter can carry out the preliminary filtration with the cleanliness factor of improving waste water with impurity such as suspended solid, colloid in the waste water for membrane element in the difficult pollution follow-up workshop section of waste water is in order to cause membrane scale deposit or jam. The dosing module is used for providing required medicament for the water softening module, and the dosing module is respectively communicated with the coagulation tank, the flocculation tank and the homogenizing tank through dosing pipelines. A dosing control valve can be arranged in the dosing pipeline to control the addition amount of the required medicament.

Preferably, the oxidation treatment module can effectively eliminate harmful microorganisms in the wastewater, and comprises at least an air compressor 401, an ozone generator 402, a tail gas destructor 403, an ozone contact tank 404, an oxygen generator 405, a refrigeration dryer 406 and a suction dryer 407. Ozone can be produced by, for example, one of electrolytic, nuclear radiation, ultraviolet, plasma, and corona discharge methods. For example, air enters the freeze-drying machine and the suction-drying machine in sequence through the air compressor, is dried and then is transmitted into the oxygen generator to prepare oxygen. The prepared oxygen can be transmitted into an ozone generator after dust filtration and pressure reduction and stabilization, and is converted into ozone under the condition of medium-frequency high-voltage discharge. The generated ozone can enter the ozone contact tank from the exhaust port of the ozone generator after being monitored and adjusted by temperature, pressure and flow. The bottom of the ozone contact tank may be supplied with ozone by means of an aeration tray. Ozone contact tank adopts inclosed mode setting to prevent that ozone from revealing, and wherein, ozone contact tank can include water inlet, outlet, air inlet and gas vent, and the waste water through the processing of pretreatment unit can get into ozone contact tank through the water inlet, and ozone passes through the air inlet and gets into ozone contact tank, and the tail gas destructor is connected in order to receive remaining ozone with the gas vent. The tail gas destructor promotes the decomposition of ozone in a heating catalysis mode so that the concentration of ozone in decomposed gas is less than 0.1 ppm.

Preferably, the pretreatment module at least comprises an ultrafiltration membrane device 501, a cartridge filter 502 and a reverse osmosis device 503, wherein the ultrafiltration membrane device is connected with the reverse osmosis device through the cartridge filter. The ultrafiltration membrane device can adopt, for example, a GTN-55-FR ultrafiltration membrane component, and the wastewater is filtered based on the ultrafiltration membrane component. Preferably, the membrane column of the ultrafiltration membrane device can adopt an internal pressure type, water flows in a positive pressure mode from inside to outside, raw water enters the membrane column from a water inlet positioned at the upper part of the membrane column, the raw water enters the outer side of the membrane thread through the membrane thread filtering membrane under the action of pressure at the inner side of the membrane thread, the permeated clean water is collected from a clean water outlet at the bottom end of the membrane column and enters the ultrafiltration water tank in a centralized mode after entering the collecting pipe. And the residual concentrated water which does not permeate the ultrafiltration membrane is refluxed and collected at the downstream of the membrane and is recycled to the water inlet through a circulating pump at the bottom of the membrane column. And the wastewater treated by the ultrafiltration membrane device is filtered again by the cartridge filter and then is conveyed to a reverse osmosis device for reverse osmosis treatment.

Preferably, the brine recycling treatment system further comprises a control module 19, wherein the control module is electrically connected with the control valve, the water quality monitor, the liquid level monitor, the pH value sensor and the dosing module, and generates a control command through corresponding signals to control the corresponding modules to execute corresponding actions. For example, when the water quality monitor detects that the water quality is not qualified, the treatment fluid in the second intermediate water tank can be circularly transferred into the bipolar membrane treatment module and the electrodialysis treatment module by controlling a device such as a lifting pump. When the water quality monitor detects that the water quality reaches the standard, the treatment fluid in the second intermediate water tank can be discharged out of the brine recovery system by controlling a device such as a lifting pump.

Preferably, the salt-containing wastewater flows through the water softening module, the oxidation treatment module, the pretreatment module, the electrodialysis treatment module and the bipolar membrane treatment module in sequence to prepare water, acid products and alkali products.

Example 4

Fig. 6 and 7 show the operating modes of two different modalities of the primary electrodialyser. As shown in fig. 6 and 7, the distance between the anion-exchange membrane 107 and the cation-exchange membrane 108 of the primary electrodialyzer can be adjusted. As shown in fig. 6, in the first configuration, both the anion exchange membrane and the cation exchange membrane defining the fresh water chamber exhibit convex configurations such that the fresh water chamber has a maximum first width D₁The adjacent concentrated water chambers have the smallest second width D₂Wherein the first width D₁Is greater than the second width D₂. As shown in FIG. 7, in the second configuration, both the anion exchange membrane and the cation exchange membrane defining the dilute chamber are recessed such that the dilute chamber has a minimum third width D₃The adjacent concentrated water chambers have the maximum fourth width D₄Wherein the fourth width D₄Is greater than the third width D₃. Preferably, the first width, the second width, the third width and the fourth width satisfy the relation D₁+D₂＝D₃+D₄. Based on the difference of the pressure difference between the water inlet and the water outlet, the anion exchange membrane or the cation exchange membrane is not in an ideal symmetrical parabolic shape after being bent, but is in an asymmetrical bent shape. For the above reasons, it can be understood that the relation D₁+D₂＝D₃+D₄There can be some error.

Preferably, the distance between the anion exchange membrane and the cation exchange membrane can be adjusted by controlling the pressure difference applied thereto. For example, in the first configuration, the pressure of the fluid in the dilute chamber is higher than the pressure in the concentrate chamber adjacent to it. The higher pressure in the dilute chamber causes its anion and cation exchange membranes to bulge out into the concentrate chamber to assume a convex configuration. The switching between the first and second configurations can be achieved by having a positive or negative pressure differential between two compartments adjacent to each other.

Preferably, the degree of curvature of the anion-exchange membrane or the cation-exchange membrane can be determined by the following method based on the theory of sheet mechanics

Depending on a constant of the ratio of the width to the length of the compartment, for example, C may be directly equal to the width/length of the dilute chamber. P represents the pressure difference to which the ion exchange membrane is subjected. W represents the width of the dilute chamber. H denotes the length of the dilute chamber. E represents the elastic modulus of the corresponding ion-exchange membrane. The width direction of the compartment refers to the direction parallel to the line connecting the anode and the cathode. The lengthwise direction of the compartment refers to the flow direction of the wastewater therein. Preferably, the pressure difference over the ion exchange membrane can be obtained by controlling the flow rate of the water inlet and/or the water outlet of the compartment. For example, when the ion exchange membrane is required to be protruded to the concentrated water chamber, the water inlet speed of the fresh water chamber can be increased and the water outlet speed of the fresh water chamber can be kept unchanged, so that the pressure of the fresh water chamber is higher than that of the adjacent compartment, and the ion membrane is protruded to the concentrated water chamber under the action of the pressure difference. Similarly, when it is desired to have the ion exchange membrane assume a concave configuration toward the dilute chamber, the outlet rate of the dilute chamber can be increased and the inlet rate can be maintained such that the pressure in the dilute chamber is lower than the pressure in the adjacent compartment. Preferably, the pressure difference of the ion-exchange membranes can be applied by a booster pump before the concentrated brine of different concentration enters the bipolar membrane electrodialyzer.

Preferably, the pressure difference applied to the ion exchange membrane can be dynamically adjusted according to at least the type of wastewater to be treated, the elastic modulus of the ion exchange membrane and the structure of the ion exchange membrane, so as to avoid shortening the service life of the ion exchange membrane due to an excessively high pressure difference. Preferably, the pressure difference of the ion exchange membrane may be set in a range of 10Pa to 2500 Pa.

Preferably, the morphological change of the ion-exchange membrane can be based on the time period T₁The process is carried out. I.e. every time T₁Ion exchange membraneThe ion exchange membrane is changed from the outward convex state to the inward concave state, or the ion exchange membrane is changed from the inward concave state to the outward convex state. Each time of the form change of the ionic membrane can be carried out in a mode of applying different pressure differences, so that the convex amount of the convex state of two adjacent times is different. For example, when the ion exchange membrane is first switched from the convex state to the concave state, the applied pressure difference is P₁Then, when the ion exchange membrane is switched from the inward concave state to the outward convex state, the applied pressure difference is P₂。P₁And P₂Different from each other, so that the amount of the outward protrusion of the ion exchange membrane is different. Preferably, the time period T for the morphological change of the ion-exchange membrane₁The formulation may be based on measuring the electrical resistance of the fluid in the compartment. For example, the change of the ion exchange membrane morphology can be realized by adjusting the water inlet pressure, the water outlet pressure, the exchange electrode and/or the exchange water inlet type through the control unit when the resistance of the concentrated brine in the concentrated brine chamber is monitored in real time and is smaller than a certain threshold value. The dynamic automatic adjustment of the ion exchange membrane form is realized through monitoring, and the scaling can be effectively inhibited.

Preferably, the morphology of the ion-exchange membrane can also be adjusted on the basis of the difference in concentration of the fluid between two compartments adjacent to each other. For example, a first reverse osmosis device 23 and a second reverse osmosis device 24 having different osmotic pressures may be provided on the first circulation path 6 and the second circulation path 7, respectively, and fluids having different concentration degrees are generated by the first reverse osmosis device 23 and the second reverse osmosis device 24 to enter the concentrate chamber and the fresh water chamber, respectively.

Example 5

Preferably, the anion exchange membrane and the cation exchange membrane in the bipolar membrane electrodialysis are also configured to have a first morphology and a second morphology of operation mode. Several biologically inert beads can also be arranged in the bipolar membrane electrodialyser. Fig. 8 shows a schematic view of the working principle of the bio-inert particle ball of the present invention. Taking the primary electrodialyzer as an example, as shown in fig. 8, the primary electrodialyzer is configured in an operation mode in which the flow direction of the fluid in the concentrate and fresh water chambers is perpendicular to the ground, and in an operation mode in which the height of the water inlet 21 from the ground is greater than the height of the water outlet 22 from the ground. A plurality of pellets 20 of biologically inert particles in the form of round balls are placed in a compartment defined by an anion exchange membrane and a cation exchange membrane. Taking the concentrate chamber 205 as an example, fluid enters the concentrate chamber through the inlet 21 and exits the concentrate chamber through the outlet 22. The shape of the bio-inert pellet sphere 20 can be defined by a spherical, cylindrical or lenticular shape, wherein the surface roughness of the bio-inert pellet sphere is less than 40 μm. The density of the bio-inert particle balls is less than the density of the fluid in the incoming concentrate chamber so that they can float up automatically based on buoyancy. The water inlet and the water outlet can be provided with filter screens, and the mesh size of the filter screens is smaller than the diameter of the biological inert particle balls so that the filter screens are always positioned in the concentrated water chamber. Under the condition that fluid enters the concentrated water chamber and the concentrated water chamber is filled, the biological inert particle balls at the water inlet sink to the water outlet under the drive of the fluid entering from the water inlet at a certain flow rate, and after the biological inert particle balls reach the water outlet, the biological inert particle balls move to the water inlet from the water outlet in a floating mode under the drive of buoyancy. The scraping and cleaning of the ion exchange membrane are finished in the process of continuous sinking and floating of the biological inert particle balls. Preferably, biologically inert particle spheres are provided in each compartment of the bipolar membrane electrodialyser and the primary electrodialyser. The bio-inert particle balls can be formed by foaming polyurethane. The density of the foam can be effectively reduced through foaming treatment, so that the density of the foam is smaller than that of the fluid.

For ease of understanding, the process of cleaning the ion exchange membrane with biologically inert particle balls is discussed.

The bio-inert particle balls can form physical and chemical cleaning to the ion exchange membrane during the displacement in the compartment. The water inlet and the water outlet of the compartment are positioned in the middle of the compartment in the width direction, and fluid is always in a flowing state from top to bottom in the direction from top to bottom of the compartment, so that the bio-inert particle balls move to the water outlet of the compartment from the center line position of the compartment. When the biological inert particle balls move to the water outlet at the bottom of the compartment, the biological inert particle balls move towards the ion exchange membrane with smaller water flow impact force respectively and move from bottom to top at the ion exchange membrane based on the action of buoyancy and the impact action of water flow. The inside of the compartment forms anticlockwise and clockwise circulating water flow, specifically, a connecting line of a water inlet and a water outlet of the compartment divides the compartment into a left part and a right part, wherein the left side of the compartment forms clockwise circulating water flow, the right side of the compartment forms anticlockwise circulating water flow, and the pellets of the bio-inert particles flow along the flowing direction of the circulating water flow respectively. Under the condition that the form of the ion exchange membrane can be dynamically changed, for example, under the form that the ion exchange membrane is concave, the bio-inert particle balls can better collide with the ion exchange membrane in the floating process to generate a scraping effect, and then scaling substances on the ion exchange membrane can be timely removed.

The bio-inert particle ball is also set to be in a working mode with an acidic or alkaline cleaning agent being arranged in the bio-inert particle ball, wherein the cleaning agent arranged in the bio-inert particle ball is discharged to the compartment through the discharge channel of the bio-inert particle ball at a set discharge speed, for example, the bio-inert particle ball is provided with a hollow cavity, the hollow cavity is used for storing the acidic or alkaline cleaning agent, and the hollow cavity is communicated with the external environment through a through hole with a set size. The cleaning agent in the hollow mould cavity is arranged in a concentration greater than the waste water in the compartment so that the cleaning agent can enter the compartment by diffusion. The size of the through hole can be set according to the actual wastewater condition and the concentration of the added cleaning agent so as to meet the continuous working time of the bio-inert particle ball, for example, the combination of the small through hole and the high concentration cleaning agent can lead to longer working time than the combination of the large through hole and the low concentration cleaning agent. The biological inert particle balls continuously release the cleaning agent in the process of attaching and moving with the ion exchange membrane, so that the scaling of the filtering membrane can be effectively inhibited.

Although the present invention has been described in detail, modifications within the spirit and scope of the invention will be apparent to those skilled in the art. Such modifications are also considered to be part of this disclosure. In view of the foregoing discussion, relevant knowledge in the art, and references or information discussed above in connection with the background, all of which are incorporated herein by reference, further description is deemed unnecessary. Further, it should be understood that aspects of the invention and portions of the various embodiments may be combined or interchanged both in whole or in part. Also, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

The foregoing discussion of the disclosure has been presented for purposes of illustration and description. It is not intended to be limited to the form disclosed herein. In the foregoing detailed description, for example, various features of the disclosure are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. Features of the embodiments, configurations or aspects may be combined in alternative embodiments, configurations or aspects to those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. Thus the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the disclosure.

Moreover, although the description of the present disclosure has included description of one or more embodiments, configurations, or aspects and certain variations and modifications, other variations, combinations, and modifications are within the scope of the disclosure, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments, configurations, or aspects to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.

Claims

1. A bipolar membrane based brine recovery system comprising at least a bipolar membrane electrodialyser located downstream of a primary electrodialyser (201), characterised in that said bipolar membrane electrodialyser is divided into at least a first compartment (109), a second compartment (110) and a third compartment (111) by at least three bipolar membranes (106) in a direction along the line connecting the anode (104) and the cathode (105) of the bipolar membrane electrodialyser, the fluid being treated at least according to the following steps, upon entering a first intermediate water basin (3):

the fluid is subjected to desalination and desalination treatment by a first circulation passage (6) defined by the primary electrodialyzer (201) and/or a second circulation passage (7) defined by the primary electrodialyzer (201) and the bipolar membrane electrodialyzer together to obtain produced water;

said fluid circulating in the form of an electrode liquid in a third circulation path (8) defined by said first compartment (109), the anode compartment (203) of the primary electrodialyser and said first intermediate water basin (3), and in a fourth circulation path (9) defined by said second compartment (110), the cathode compartment (202) of the primary electrodialyser and said first intermediate water basin (3), respectively, wherein,

the first compartment (109) is configured in a working mode in which the fluid treated by it can neutralize, in the third circulation path (8), the fluid formed by treatment of the anode compartment (203) and the second compartment (110) is configured in a working mode in which the fluid treated by it can neutralize, in the fourth circulation path (9), the fluid formed by treatment of the cathode compartment (202);

a number of bio-inert particle balls (20) with a density less than the fluid density are embedded in each of the primary electrodialyser (201) and the bipolar membrane electrodialyser, the bio-inert particle balls (20) being configured to: moving from the water inlet (21) of the primary electrodialyser to the water outlet (22) thereof in a sinking manner by the entrainment of the fluid, and moving from the water outlet (22) thereof to the water inlet thereof in a floating manner by the entrainment based on buoyancy; or the water inlet (21) of the bipolar membrane electrodialyzer moves to the water outlet (22) thereof in a sinking mode through the driving of the fluid, and the water outlet (22) moves to the water inlet (21) thereof in a floating mode through the driving of buoyancy; the brine recovery system further comprises a waste water reduction unit (2), the waste water reduction unit (2) being configured to: obtaining at least a first concentration of concentrated brine and a second concentration of concentrated brine having different salt contents from each other based on the first reverse osmosis unit (23), the second reverse osmosis unit (24) and/or a combination of both, the fluid comprising at least the first concentration of concentrated brine and the second concentration of concentrated brine, wherein,

said fluid being able to enter the primary electrodialyser (201) in a manner such as to have at least a different flow rate and/or a different density, so as to have a pressure difference between its adjacent concentrate (205) and fresh water (204) chambers, wherein,

in the case where at least two ion exchange membranes defining the concentrate or dilute chambers move in an opposite manner to form a minimum distance based on the pressure difference, the fluid entering the respective reaction chamber has a greater density than the fluid in the reaction chamber adjacent thereto so that the bio-inert particle balls (20) therein float at a greater velocity.

2. Brine recovery system according to claim 1, wherein the fluid in the first circulation path (6) is passed in a first direction of flow into the fresh water compartment (204) of the primary electrodialyzer (201) for desalination and desalination, and the fluid in the second circulation path (7) is passed in a second direction of flow into the concentrate compartment (205) of the primary electrodialyzer (201) for concentration,

the first direction and the second direction are configured in parallel and opposite configurations to each other such that a concentration difference between the concentrate chamber (205) and the dilute chamber (204) is minimized within the same plane perpendicular to the first direction or the second direction.

3. Brine recovery system according to claim 2, characterized in that an anion exchange membrane (107) and a cation exchange membrane (108) are arranged between two of said bipolar membranes (106) such that said bipolar membrane electrodialyser presents the morphology of a first compartment (109), a third compartment (111), a fourth compartment (112), a fifth compartment (113), a sixth compartment (114) and a second compartment (110) in that order, in the direction along its anode (104) directed towards its cathode (105),

the fluid of the second circulation channel (7) flows through the concentrated water chamber (205), the third compartment (111) and the fifth compartment (113) in sequence along a third direction to carry out desalination and desalination treatment so as to obtain the produced water;

the produced water enters the fourth compartment (112) and the sixth compartment (114) in a fourth direction for treatment to obtain an acid product and a base product, respectively, wherein the third direction and the fourth direction are parallel and opposite to each other.

4. Brine recovery system according to claim 3, wherein a pH sensor (14) is arranged in the first intermediate water basin (3) for monitoring the pH of the fluid, wherein,

in the case where the fluids of the third circulation path (8) and the fourth circulation path (9) are returned to the first intermediate water tank (3), the acid product or the base product can be returned to the first intermediate water tank (3) to adjust the pH of the fluids when the pH monitored by the pH sensor (14) is out of a set range.

5. Brine recovery system according to claim 4, further comprising a water quality monitor (12) arranged in the second intermediate basin (4), wherein,

the water quality monitor (12) is configured to be capable of monitoring at least the operating mode of chloride ion concentration, heavy metal ion concentration and/or suspended matter content;

and the fluid in the second intermediate water tank (4) is circularly treated in a mode of following the first circulation passage (6) and/or the second circulation passage (7) until the effluent index of the fluid meets the preset standard of the water quality monitor (12).

6. Brine recovery system according to claim 5, wherein a liquid level monitor (13) is arranged in the second intermediate water basin (4), wherein the second intermediate water basin (4) is replenished with fluid in communication with the first intermediate water basin (3) in case the liquid level monitor (13) monitors that the liquid level of the fluid in the second intermediate water basin (4) is lower than a first preset level, wherein the communication between the first intermediate water basin (3) and the second intermediate water basin (4) is cut off in case the liquid level of the fluid in the second intermediate water basin (4) is higher than a second preset level, wherein,

and under the condition that the first intermediate water tank (3) is not communicated with the second intermediate water tank (4), the fluid in the second intermediate water tank (4) is circularly treated in a mode of following the first circulating passage (6) and/or the second circulating passage (7) until the effluent index of the fluid meets the preset standard of the water quality monitor (12).

7. A saltwater recovery system for scale inhibition, comprising at least the primary electrodialyzer (201) of any one of claims 3 to 6 and the bipolar membrane electrodialyzer, wherein,

the bipolar membrane electrodialyzer is configured to: -the fluid treated by the first compartment (109) is capable of neutralizing in the third circulation path (8) the operating mode of the fluid formed by treatment of the anodic compartment (203) and acidic, the second compartment (110) is configured in such a way that the fluid treated by it is capable of neutralizing in the fourth circulation path (9) the operating mode of the fluid formed by treatment of the cathodic compartment (202) and basic;

the primary electrodialyser is configured to: fluid enters the concentrate (205) and the dilute (204) chambers respectively with a pressure difference, wherein the anion exchange membrane (107) and/or the cation exchange membrane (108) between adjacent concentrate (205) and dilute (204) chambers can be shifted a first distance in a first direction parallel to the line connecting the cathode (105) and the anode (104) based on the pressure difference to form a first working configuration, and the ion exchange membrane can be shifted a second distance in a second direction parallel to the line connecting the cathode and the anode based on the change of the pressure difference to form a second working configuration,

the conductivity in the concentrate chamber (205) and/or the conductivity in the dilute chamber (204) is above a threshold (M)₁) In the case of (2), switching between the first operation mode and the second operation mode is realized.

8. Brine recovery system according to claim 7, wherein the ion exchange membranes defining the dilute chamber (204) are moved in a diverging manner in the first and second directions, respectively, to form a first width (D) from each other in case of a positive pressure difference between the dilute chamber (204) and the concentrate chamber (205)₁) A second width (D) of the ion exchange membranes defining the concentrate chambers that are displaced in an opposing manner in the first and second directions, respectively, to form each other₂) Wherein, in the step (A),

by the first width (D)₁) And said second width (D)₂) Defining said first operating configuration.

9. Brine recovery system according to claim 8, wherein the ion exchange membranes defining the concentrate chambers are moved in a diverging manner in the first and second direction, respectively, to form a fourth width (D) from each other in case of a negative pressure difference between the fresh water chamber (204) and the concentrate chamber (205)₄) The ion exchange membranes defining the dilute chambers (204) are moved in an opposing manner along the first and second directions, respectively, to form a third width (D) therebetween₃) Wherein, in the step (A),

by the fourth width (D)₄) And the third width (D)₃) Defining said second operating configuration.

10. Brine recovery system capable of self-cleaning ion-exchange membranes, characterized in that at least a primary electrodialyser (201) and a bipolar membrane electrodialyser according to one of the preceding claims are used, wherein,

the fluid can enter the primary electrodialyzer (201) and/or the bipolar membrane electrodialyzer in such a way that the flow direction of the fluid is perpendicular to the filtration permeation direction of the ion exchange membrane, wherein a plurality of bio-inert particle balls (20) with a density less than the fluid density are arranged in each of the primary electrodialyzer (201) and the bipolar membrane electrodialyzer,

the bio-inert particle balls (20) are configured to: moving from the water inlet (21) of the primary electrodialyser to the water outlet (22) thereof in a sinking manner by the entrainment of the fluid, and moving from the water outlet (22) thereof to the water inlet thereof in a floating manner by the entrainment based on buoyancy; or the water inlet (21) of the bipolar membrane electrodialyzer moves to the water outlet (22) thereof in a sinking mode through the driving of the fluid, and the water outlet (22) moves to the water inlet (21) thereof in a floating mode through the driving of buoyancy;

the brine recovery system further comprises a waste water reduction unit (2), the waste water reduction unit (2) being configured to: obtaining at least a first concentration of concentrated brine and a second concentration of concentrated brine having different salt contents from each other based on the first reverse osmosis unit (23), the second reverse osmosis unit (24) and/or a combination of both, the fluid comprising at least the first concentration of concentrated brine and the second concentration of concentrated brine, wherein,

11. Brine recovery system according to one of the claims 1 to 10, wherein a first bipolar membrane electrodialyser (101) and a second bipolar membrane electrodialyser (102) located downstream thereof each have at least one of said third compartments (111), wherein,

the third compartment (111) and the first compartment (109) are adjacent to each other, and the fluid treated by the concentrated water chamber (205) in the second circulation passage (7) flows through the third compartment (111) and the fifth compartment (113) in sequence in a manner of firstly entering the second bipolar membrane electrodialyzer (102) to carry out desalination and desalination treatment.

12. The brine recovery system according to claim 11, further comprising a water softening module (15), an oxidation treatment module (16) and a pre-treatment module (17), raw water being treated in such a way that it flows through the water softening module (15), the oxidation treatment module (16) and the pre-treatment module (17) in sequence to obtain said fluid entering the first intermediate basin (3),

the raw water is softened and filtered by the water softening module (15) in a mode of sequentially flowing through a homogenizing tank (301), a coagulation tank (302), a flocculation tank (303), a sedimentation tank (304) and a sand filter (305) to obtain a first treatment liquid.

13. Brine recovery system according to claim 12, wherein said oxidation treatment module (16) comprises at least an ozone generator (402) for producing ozone and an ozone contact tank (404) for performing oxidation reactions, wherein,

the first treatment liquid is subjected to oxidation treatment in such a manner that the first treatment liquid and the ozone are simultaneously introduced into the ozone contact tank (404) to obtain a second treatment liquid.

14. The brine recovery system according to claim 13, wherein said pre-treatment module (17) comprises at least an ultrafiltration membrane device (501), a cartridge filter (502) and a reverse osmosis device (503), wherein,

and filtering the second treatment liquid by the ultrafiltration membrane device (501) and the cartridge filter (502) in sequence, and performing reverse osmosis concentration treatment by the reverse osmosis device (503) to obtain the fluid.