JP2003001258A - Electrolytic deionizing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic deionizing apparatus capable of sufficiently removing even weak electrolytes such as silica and boron and capable of obtaining high quality treated water having a high specific resistance by a single apparatus. SOLUTION: Raw water is introduced from raw water supply piping 5 into primary desalting chambers 1 and treated water (primarily desalted water) in the chambers 1 is introduced from piping 6 into secondary desalting chambers 2. Treated water (secondarily desalted water) in the chambers 2 is drawn as treated water. Part of the primarily desalted water is drawn by piping 8 from the piping 6 and fed to concentration chambers 3, 4, a cathode chamber 18 and an anode chamber 17, and waste water from the concentration chambers 3, 4, the cathode chamber 18 and the anode chamber 17 is drawn as concentrated waste water through piping 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric deionization apparatus for producing deionized water used in various industries in the fields of semiconductors, liquid crystals, pharmaceuticals, foods, electric power, etc., for consumer use or in research facilities, and in particular, TECHNICAL FIELD The present invention relates to an electric deionization device capable of dramatically improving the removal rates of weak electrolytes such as silica and boron and organic substances, and capable of producing high-quality deionized water having a specific resistance value of 18.0 MΩ · cm or more. .

[0002]

2. Description of the Related Art Conventionally, in the production of deionized water used in various industries such as a semiconductor manufacturing factory, a liquid crystal factory, a food industry, an electric power industry, and a consumer or research facility, as shown in FIG. A plurality of anion exchange membranes 13 and cation exchange membranes 14 are alternately arranged between the electrodes (anode 11 and cathode 12) to alternately form a concentrating chamber 15 and a desalting chamber 16, and the desalting chamber 16 is ion-exchanged. An electric deionization device in which an anion exchanger composed of a resin, an ion exchange fiber, a graft exchange or the like and a cation exchanger are mixed or filled in a multi-layered form is frequently used (Japanese Patent Nos. 1782943 and 27).
51090, Japanese Patent No. 2699256). Reference numeral 17 is an anode chamber and 18 is a cathode chamber.

In general, an electric deionization apparatus produces H ⁺ ions and OH − ions by water dissociation, and continuously regenerates an ion exchanger filled in a desalting chamber to efficiently perform deionization. Salt treatment is possible. Electrodeionization equipment does not require regeneration treatment using chemicals such as ion exchange resin equipment, which has been widely used for desalination treatment, and enables complete continuous water sampling, producing highly pure water. It has the advantage of being able to

In order to remove weak electrolytic substances such as carbon dioxide (CO ₂ ), silica and boron with such an electric deionization device, the following ionization reaction is caused in the demineralization chamber to generate ions. Need to occur. CO ₂ + OH ⁻ → HCO ₃ ⁻ (pKa = 6.35) SiO ₂ + OH ⁻ → HSiO ₃ ⁻ (pKa = 9.86) H ₃ BO ₃ + OH ⁻ → B (OH) ₄ ⁻ (pKa = 9.24)

Among these weak electrolytic substances, substances such as CO ₂ having a low dissociation constant pKa value can be completely removed by a conventional electric deionization apparatus by increasing the applied voltage to cause water dissociation. However, substances having a high dissociation constant such as silica and boron can be removed only up to about 60 to 90% even if the applied voltage is increased.

In order to solve such problems, the following methods have been conventionally proposed. A method in which the ion-exchange layer in the desalting chamber is filled with multiple layers including an anion-exchange layer and a cation-exchange layer, and the anion-exchange layer is temporarily made alkaline (JP-A-4-71624). pH 9.5 to 11.5
(USP 4,298,442) In order to remove silica, a conventional electrodeionization device is provided in multiple stages to allow water to pass therethrough, or a RO membrane device in the previous stage is provided in multiple stages.

[0007]

In the method of filling the ion exchange layer in the desalting chamber with a multi-layered packing, the silica concentration required in the semiconductor field etc. <0.1 ppb cannot be achieved.

In the method of raising the pH of the raw water, the removal efficiency of silica is improved by about 5 to 10%, but a chemical injection facility such as caustic soda is required for adjusting the pH. Hardness components such as Ca ²⁺ and Mg ^{2+ in} raw water generate scale, so it is necessary to completely remove them with a softening device, etc.
Equipment costs increase.

In the method of (1), since the water treated by the electric deionization apparatus contains silica and boron in an amount of 0.5 to 1.0 ppb or more, the non-regeneration type mixed bed ion exchange apparatus is provided at the subsequent stage of the electric deionization apparatus. Need to be placed.

The present invention solves the above-mentioned conventional problems, does not inject a chemical solution such as caustic soda, does not produce scale, and has an extremely high removal rate of weak electrolytes such as silica and boron. The purpose is to provide.

Another object of the present invention is to provide an electrodeionization device capable of removing organic substances.

[0012]

The electrodeionization device of the present invention (claim 1) is alternated by arranging a cathode, an anode, and a plurality of cation exchange membranes and anion exchange membranes between the cathode and the anode. In an electric deionization apparatus having a concentrating chamber and a demineralizing chamber formed in the above, and an ion exchanger filled in the demineralizing chamber, the demineralizing chamber has a large thickness and a primary demineralizing chamber. Small secondary desalination chambers are alternately arranged, raw water is introduced into the primary desalination chamber, primary deionized water flowing out from the primary desalination chamber is introduced into the secondary desalination chamber, The secondary demineralized water from the secondary demineralization chamber is taken out as treated water, and a part of the primary demineralized water is passed to each of the concentration chambers.

The electrodeionization device of the present invention (claim 2) is formed alternately by arranging a cathode, an anode, and a plurality of cation exchange membranes and anion exchange membranes between the cathode and the anode. In an electric deionization apparatus having a concentrating chamber, a demineralizing chamber, and an ion exchanger filled in the demineralizing chamber, the demineralizing chamber includes a primary demineralizing chamber having a large thickness and a secondary demineralizing chamber having a small thickness. The salt chambers are alternately arranged, the raw water is introduced into the primary demineralizing chamber, and the primary demineralized water flowing out from the primary demineralizing chamber is used in the second
The secondary demineralized water is introduced into the secondary demineralizing chamber, the secondary demineralized water from the secondary demineralizing chamber is taken out as treated water, and raw water is stored in the concentrating chamber in which the primary demineralizing chamber is arranged on the cathode side through the anion exchange membrane. Water is passed,
A feature is that a part of the primary demineralized water is passed through a concentrating chamber in which a secondary demineralizing chamber is arranged on the cathode side via an anion exchange membrane. In addition, the present invention (Claim 2) can increase the amount of the primary demineralized water introduced into the secondary demineralization chamber as compared with the above-mentioned invention (Claim 1), so that more secondary demineralized water can be obtained. Is advantageous.

Generally, in the electric deionization apparatus, the limiting current density is
Demineralization is performed by passing the above current, but at this time, as described above.
Water dissociation occurs in OH⁻, H⁺Will occur and carry the charge
Growls This H⁺The ion mobility of ions is 349.7.
cm^TwoΩ^-1eq^-1And the ion mobility of other ions
(30-70 cm^TwoΩ^-1eq^-1) Compared to
Fast (ion mobility data for infinitely diluted solutions, day
(See "Chemical Handbook" edited by the Chemical Society of Japan). For this reason, especially in the desalting chamber
When the thickness W of the
The difference in movement speed due to the difference in mobility spreads, and H⁺Is fast
Crab is discharged to the concentration chamber side, OH⁻Ions are taken into the desalting chamber
It is easy to be left behind. Also, Ca²⁺, Mg²⁺Such as multivalent
Cations and anions are relatively easily discharged to the concentration chamber side.
But Na ⁺, K⁺Is monovalent and H⁺Ion
Since it plays a role of carrying electric charges, it is easy to remain in the desalination chamber. This
As a result of the
Alkali metal hydroxide is added, treated water
The pH of (deionized water) becomes alkaline.

For the same reason, the pH of the concentrated water is conversely acidic.

For this reason, in the electric deionization apparatus of the present invention, the primary deionization chamber having a large thickness becomes alkaline, and weak electrolytic substances such as silica and boron are ionized and efficiently removed. The primary demineralized water is passed through a secondary demineralization chamber (a demineralization chamber having a small thickness as in the conventional case) to remove strong electrolytic substances, and as a result, the treated water of high specific resistance and good water quality. Can be obtained.

Since the primary demineralized water containing almost no weak electrolytic substance is passed to the concentrating chamber adjacent to the secondary demineralizing chamber through the anion exchange membrane, the secondary demineralizing chamber is concentrated. The weak electrolyte does not come back into the chamber.

Further, according to the present invention, it is possible to obtain the treated water of high quality with one apparatus without connecting the electric deionization apparatus in multiple stages.

In the present invention, at least one of the primary desalination chamber and the secondary desalination chamber may contain a substance having an organic substance decomposing ability.

As a substance having this organic substance decomposing ability,
Examples include granular carriers carrying metal and activated carbon. It is presumed that the substance having the ability to decompose organic matter probably decomposes the organic matter into organic acid, and the organic acid is dissociated into ions and discharged to the concentration chamber.

In the present invention, a high-order demineralization chamber through which secondary demineralized water flows may be provided.

In the present invention, the desalting chamber has a primary desalting chamber having a property that the pH of the desalinated water is increased by 1 or more as compared with the raw water by passing the raw water through the desalting chamber, and an anion exchanger layer. The secondary desalting chambers in which the cation exchanger layers are alternately filled may be alternately arranged. In this case, it is preferable that the primary desalination chamber has a thickness of 7 mm or more, or has a configuration in which only an anion exchanger is filled as an ion exchanger through which raw water is first passed.

[0023]

DETAILED DESCRIPTION OF THE INVENTION Embodiments will be described below with reference to the drawings. 1 and 2 are schematic configuration diagrams of the electric deionization apparatus according to the embodiment. First,
In any of the drawings, a plurality of anion exchange membranes A and cation exchange membranes C are alternately arranged between the anode 11 and the cathode 12 to alternately form a concentration chamber and a desalting chamber. Two
Further, an anion exchanger and an anion exchanger made of an ion exchange resin, an ion exchange fiber, a graft exchange or the like are mixed or packed in a multi-layered manner. Anode 11 and cathode 12
An anode chamber 17 and a cathode chamber 18 are provided along the above.

The desalination chamber comprises a primary desalination chamber 1 having a thickness of 7 mm or more and a secondary desalination chamber 2 having a thickness of less than 7 mm. The thickening chambers 3 and 4 have the same thickness.

A primary demineralization chamber 1 having a large thickness is arranged in the cathode chamber 18 via a cation membrane C, and thereafter, a concentrating chamber 3, a secondary demineralizing chamber 2, a concentrating chamber 4, and a primary chamber are directed toward the anode 11. Desalination chamber 1,
The concentrating chamber 3 and the secondary desalting chamber 2 are arranged in this order. In addition,
In FIGS. 1 and 2, two primary demineralization chambers 1 and two secondary demineralization chambers 2 are arranged, but the number of arrangements is not limited to this.

The reference numeral 3 is attached to the concentration chamber in which the primary deionization chamber 1 is arranged on the cathode side through the anion exchange membrane A,
The reference numeral 4 is attached to the concentrating chamber in which the secondary desalting chamber 2 is arranged on the cathode side via the anion exchange membrane A.

In FIG. 1, the raw water is the raw water supply pipe 5.
Is introduced into the primary desalination chamber 1, and the treated water in the primary desalination chamber 1 (primary desalination water) is introduced from the pipe 6 into the secondary desalination chamber 2. Treated water (secondary demineralized water) in the secondary desalination chamber 2 is taken out as treated water through the pipe 7.

A part of the primary demineralized water is collected from the pipe 6 by the pipe 8 and is passed through the concentration chambers 3, 4 and the cathode chamber 18 and the anode chamber 17, respectively. Wastewater from the cathode chamber 18 and the anode chamber 17 is taken out as concentrated wastewater through the pipe 9. This concentrated wastewater is, for example, reverse osmosis (RO)
Sent to the processing system.

In FIG. 2, raw water is passed to the concentrating chamber 3 through the pipe 8b branched from the raw water supply pipe 5,
The concentrated waste water from the concentrating chamber 3 is taken out from the pipe 9b and sent to, for example, a reverse osmosis treatment device. Concentration chamber 4, cathode chamber 18
The primary demineralized water is introduced into the anode chamber 17 via the pipe 8a branched from the pipe 6, and the drainage thereof is taken out via the pipe 9a and sent to, for example, a separate electric deionization device.

In such an electric deionization apparatus, the primary deionization chamber 1 has a large thickness, and its internal pH becomes alkaline which is preferably higher than that of raw water by 1 or more, and weak electrolytes such as silica and boron are ionized and concentrated. It is discharged to the chamber 3. In the secondary deionization chamber 2 having a small thickness, the strong electrolyte is efficiently deionized, and the secondary deionized water has a high specific resistance. 2
Since the primary demineralized water from which silica, boron, etc. have been removed is passed through the concentrating chamber 4 and the anode chamber 17 which are adjacent to the secondary demineralizing chamber 2 via the anion exchange membrane A, the anode chamber 1
7 and the weak electrolytic substance do not reversely mix into the secondary desalination chamber 2 from the concentration chamber 4.

Next, a more preferable embodiment of the device of the present invention and the operating method thereof will be described.

(1) The thickness of the primary deionization chamber 1 is 7 to 300.
mm Particularly preferably 8 to 30 mm. The thickness of the secondary desalination chamber 2 is 1.0 mm or more and less than 7 mm, and particularly preferably 2 to 5 mm. However, when the ion exchanger filled in the desalination chamber comprises anion exchange resin and cation exchange resin arranged alternately, or when the contact efficiency with the ion exchange resin is improved, etc. The thickness of the desalting chamber can be up to 15 mm if the treated water has a high specific resistance even if it is thick.

(2) As the ion exchange membrane, either a homogeneous membrane or a heterogeneous membrane can be used.

(3) The ion exchanger filled in the desalting chamber is most preferably a mixed layer of anion and cation resin, and when the applied voltage is increased, the primary desalting chamber 1 can have the same effect even if it is an anion single layer. To be However, Ca ²⁺ in the primary desalination chamber,
A mixed layer is preferable to remove Mg ²⁺ .
The volume ratio of the anion resin to the cation resin is 6: 4 to 9: 1, preferably about 7.5: 2.5. The cationic resin is necessary for removing Ca ^2+, which is a factor of scale generation, in the primary desalting chamber. In this case, the volume ratio of the ion exchanger is measured by the regeneration type (OH type, H type).

(4) Examples of the type of ion exchanger include a bead-shaped or fibrous ion-exchange resin, and a graft polymerization exchanger in which an exchange group is introduced into a fiber or a nonwoven fabric by utilizing graft polymerization. In order to obtain good water quality, a beaded ion exchange resin having a uniform size is preferable. "Ion exchange resin of uniform size" refers to those in which 90% of the beads are within 10% of the average bead size and the relative average size of the anion exchange resin and cation exchange resin in the bead mixture is at least 0.8.

(5) In FIGS. 1 and 2, the concentrated water is made to flow in parallel in the same direction as the desalting chamber, but the concentrated water is made to flow in the opposite direction to the desalting chamber (the desalting chamber). Is downward flow,
Upflow may be used in the concentrating chamber).

(6) It is preferable to fill the concentrating chamber, through which the low-conductivity primary demineralized water is passed, with an ionic conductor or an electronic conductor. Ion conductor is an ion exchange resin,
Ion exchange fibers, and those obtained by introducing functional groups into the nonwoven fabric by graft polymerization, etc. The electronic conductor means granular, fibrous activated carbon, metal beads and the like. As a result, 50μ
Even if water having a low conductivity of s / cm or less is passed through the concentrating chamber, it is possible to secure a current value necessary for removing the weak electrolytic substance without adding a chemical such as sodium chloride.

(7) In the electrode chamber (cathode chamber and anode chamber)
Ion exchange resin, ion exchange fiber, activated carbon, etc.
It is preferable to fill the conductor. Especially large surface area
Activated carbon fiber is the most preferred because it is easy to handle.
Yes. Even in the past, it was possible to fill the electrode chamber with an ionic conductor.
However, some of the water to be treated was branched and passed through the electrode chamber.
It was common to do. This is Ca scale in the electrode chamber.
Or chlorine ions on the anode side_TwoIn
Therefore, there is a problem that the oxidative deterioration of the ion exchanger is severe. Two
Cl⁻→ Cl_Two+ 2e⁻ As shown in Figs. 1 and 2, Ca²⁺,
Cl⁻Passing primary demineralized water that does not contain ions to the electrode chamber
As a result, deterioration of the filling is prevented and stable operation for a long time is possible.
can do.

(8) Examples of the substance capable of decomposing organic substances include activated carbon (or granular activated carbon), and metal or metal oxide. The metal or metal oxide is preferably supported on activated carbon, ion exchange resin, ion exchange fiber or the like. Examples of the metal include platinum and cobalt. The substance having this organic matter decomposing ability is placed in one or both of the primary desalination chamber and the secondary desalting chamber, but considering that eluate may occur, it is placed only in the primary desalting chamber. Preferably. The substance having the organic substance decomposing ability may be mixed and filled with the ion exchanger, or may be filled so as to form a packed layer separate from the ion exchanger. As a result of various experiments, it was found that about 30 to 50% of the TOC component can be removed by filling with a substance having this organic substance decomposing ability.

(9) When the apparatus of the present invention is operated, the oxidation aid is added in an amount of 2 to 20 times, preferably 10 times the TOC concentration in the water to be treated, with respect to the raw water introduced into the primary desalting chamber. Then, the removal rate of the nonionic organic matter is improved by 20 to 40% as compared with the case where no addition is made. Examples of the oxidation aid include hydrogen peroxide, ozone, and oxidizing agents such as potassium permanganate. Considering impurities and durability of constituent members,
Hydrogen peroxide is preferred.

(10) By introducing a TOC decomposition device such as an ultraviolet oxidation device between the primary desalination chamber and the secondary desalination chamber, organic substances can be stably removed.

[0042]

EXAMPLES In the following examples and comparative examples, the following (1) to
The equipment of (4) was connected in series to treat city water. That is,
City water was treated with activated carbon, then subjected to RO (reverse osmosis) treatment, membrane degassing treatment, and then passed through an electric deionization device. (1) Activated carbon device: "Kurikoru KW10-30" manufactured by Kurita Industry Co., Ltd. (2) RO device: "Membrane Ace KN200" manufactured by Kurita Industry Co., Ltd. (3) Membrane deaerator: SEPARELEF040P (4) Electrodeionization Equipment: "Pure Ace PA-200" manufactured by Kurita Water Industries Ltd.

Comparative Example 1 The following was used as the ion exchange membrane, and the following anion exchange resin and cation exchange resin were used as the ion exchange resin to be filled in the primary deionization chamber: anion exchange resin: cation exchange resin = 7 The ratio of 6: 4 (volume ratio) was used for the secondary deionization chamber and the concentration chamber, and the ratio was 6: 4. Assembled. Anion Exchange Membrane: “Neoceptor AH” manufactured by Tokuyama Corporation
A "cation exchange membrane:" Neoceptor CM "manufactured by Tokuyama Corporation
B "Anion exchange resin: Dow Chemical's" Marathon A "Cation exchange resin: Dow Chemical's" Marathon C "

In FIG. 3, the pipe 8 in FIG. 1 is branched from the raw water pipe 5 instead of the primary demineralized water pipe 6, and raw water is passed through the electrode chambers 17 and 18 and the concentration chambers 3 and 4. The other configurations are exactly the same as those in FIG.

The thickness and vertical and horizontal dimensions of the desalination chamber and the concentration chamber are as follows. Primary desalination chamber thickness: 15 mm, width: 150 mm, height: 5
00 mm, secondary desalination chamber thickness: 5 mm, width: 150 mm, height: 50
0 mm, concentration chamber thickness: 5 mm, width: 150 mm, height: 500 m
m, the number of primary desalination chambers and the number of secondary desalination chambers are two as shown in FIG.

As the anion exchange resin and the cation exchange resin, those thoroughly washed with ultrapure water were used. The electrode chamber was filled with activated carbon fiber Cractive FT manufactured by Kuraray Chemical Co., Ltd.

Water was passed through this electric deionization apparatus under the following conditions, and the specific resistance value of treated water, the measurement result of silica, boron and other ions and the removal rate were examined. The results are shown in Table 1. . Water flow rate: 200 L / h Voltage: 30 V Current: 3 A Recovery rate: 80%

Example 1 The same treatment as in Comparative Example 1 was carried out except that the pipe 8 was connected to the primary deionized water pipe 6 as shown in FIG. The specific resistance value of the treated water, the measurement results of silica, boron and other ions and the removal rate were examined, and the results are shown in Table 1.

Example 2 The pipes 8a, 8b, 9a and 9b are connected as shown in FIG.
The measurement was performed by passing water in the same manner as in Comparative Example 1 and Example 1 except that the applied voltage was 25V. The results are shown in Table 1.

Example 3 Water was passed in the same manner as in Example 2 except that the thickness of the primary deionization chamber was set to 7 mm and all the ion exchange resins to be filled were anion exchange resins. The results are shown in Table 1.

[0051]

[Table 1]

As shown in Table 1, according to the examples of the present invention, treated water having high specific resistance from which silica and boron are sufficiently removed can be obtained.

Example 4 20% of granular activated carbon supporting platinum in the primary deionization chamber
added. Other configurations were the same as those in the first embodiment.

To this electric deionization apparatus, city water to which isopropyl alcohol (IPA) was added so as to be 100 ppb as C was passed in the same manner as in Example 1 to obtain T
The OC concentration was measured. The results are shown in Table 2.

For comparison, the above-mentioned Examples 1, 2,
The TOC concentration was measured by passing city water containing IPA to the apparatus of No. 3, and the results are shown in Table 2.

Further, in this Example 4, H was added to the raw water.
Water was passed in the same manner except that 1 ppm of ₂ O ₂ was added,
The TOC concentration was measured. The results are shown in Table 2.

[0057]

[Table 2]

As shown in Table 2, the TOC component can be decomposed by adding activated carbon to the ion exchange resin in the primary desalting chamber. At this time, by adding H ₂ O ₂ ,
Decomposition is accelerated. In this case, the processing load can be reduced when the TOC decomposition ultraviolet oxidation device is also used.

[0059]

As described above, according to the present invention, silica,
Weak boron, etc. can be removed sufficiently, high specific resistance,
Provided is an electric deionization device capable of obtaining high-quality treated water with one device. In the present invention, it is also possible to remove the organic substance by filling the desalting chamber with a substance having the ability to decompose the organic substance.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electrodeionization device according to an embodiment.

FIG. 2 is a configuration diagram of an electric deionization apparatus according to another embodiment.

FIG. 3 is a configuration diagram of an electrodeionization device according to a comparative example.

FIG. 4 is a configuration diagram of a conventional electrodeionization device.

[Explanation of symbols]

1 Primary desalination chamber 2 Secondary desalination chamber 3,4 Concentration chamber 10 Ion exchanger 11 Anode 12 cathode 13, A Anion exchange membrane 14, C cation exchange membrane 15 Concentration room 16 Desalination chamber 17 Anode chamber 18 Cathode chamber

Continued front page    F-term (reference) 4D006 GA17 JA30Z JA41Z JA44B                       JA56Z KA26 KA31 KA33                       KA63 KB01 KB30 KD01 KD21                       KD22 MA03 MA13 MA14 MB07                       PA01 PB02 PC01 PC11 PC31                       PC42                 4D050 AA05 AB07 BB02 BB09 BB11                       BC05 BC06 BC10 BD02 CA03                       CA06 CA09                 4D061 DA02 DB13 EA09 EB04 EB13                       EB17 EB19 ED01 ED02 ED03                       FA08 FA16

Claims (7)

[Claims] 1. A cathode, an anode, a concentrating chamber and a desalting chamber alternately formed by arranging a plurality of cation exchange membranes and anion exchange membranes between the cathode and the anode, and filling the desalting chamber. In the electric deionization apparatus having a deionized ion exchanger, the deionization chamber has a large thickness of the primary deionization chamber and a small thickness of 2
Secondary demineralization chambers are alternately arranged, raw water is introduced into the primary demineralization chamber, primary demineralized water flowing out from the primary demineralization chamber is introduced into the secondary demineralization chamber, and secondary demineralization chamber is introduced. An electric deionization device, wherein secondary demineralized water from the demineralization chamber is taken out as treated water, and a part of the primary demineralized water is passed to each of the concentration chambers. 2. A cathode, an anode, a concentrating chamber and a desalting chamber alternately formed by arranging a plurality of cation exchange membranes and anion exchange membranes between the cathode and the anode, and filling the desalting chamber. In the electric deionization apparatus having a deionized ion exchanger, the deionization chamber has a large thickness of the primary deionization chamber and a small thickness of 2
Secondary demineralization chambers are alternately arranged, raw water is introduced into the primary demineralization chamber, primary demineralized water flowing out from the primary demineralization chamber is introduced into the secondary demineralization chamber, and secondary demineralization chamber is introduced. Secondary demineralized water from the desalination chamber is taken out as treated water, raw water is passed through the anion exchange membrane on the cathode side to the concentrating chamber where the primary desalination chamber is arranged, and anion exchange membrane is placed on the cathode side. An electric deionization device, wherein a part of the primary demineralized water is passed through a concentrating chamber in which a secondary demineralizing chamber is arranged via the. 3. The thickness of the primary desalination chamber according to claim 1 or 2, and the thickness of the secondary desalination chamber is 7 mm or more.
An electric deionization apparatus characterized by being less than m. 4. The method according to claim 1, wherein at least one of the primary desalination chamber and the secondary desalination chamber contains a substance having an organic substance decomposing ability. Electrodeionization equipment. 5. The high-order desalination chamber having a smaller thickness than that of the secondary desalination chamber according to claim 1, wherein the desalination chamber has a larger thickness and a smaller thickness. An electric deionization device characterized in that water is sequentially supplied to the deionization chamber. 6. The primary desalination chamber according to claim 1 or 2, wherein the desalination chamber has a property that when the raw water is passed through the desalination chamber, the pH of the desalinated water is increased by 1 or more than that of the raw water. , Anion exchanger layers and cation exchanger layers were alternately packed 2
An electric deionization device having a configuration in which secondary deionization chambers are alternately arranged. 7. The method according to claim 6, wherein the primary deionization chamber has a thickness of 7 mm or more, or has a structure in which only an anion exchanger is filled as an ion exchanger through which raw water is first passed. Characterized electric deionization device.