JP2018001106A - Electrodeionization device and method for operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeionization device having reduced increase of voltage even if being operated at a high current density of 500 mA/dm, capable of improving a boron removal rate, and further capable of preventing the reduction of the device life.SOLUTION: Provided is an electrodeionization device 1 in which the ratio between the anion exchange resin and the cation exchange resin in an ion exchange resin filled into a desalination chamber 7 is (80:20) to (60:40). In the ion exchange resin, at least, as the cation exchange resin, the one beforehand subjected to conditioning (cleaning) so as to control a TOC elution amount to 1 ppb or lower is used. Further, in an anion exchange membrane 4 and a cation exchange membrane 5, at least as the anion exchange membrane 4, a heterogeneous membrane is adopted.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrodeionization apparatus and an operation method thereof, and more particularly to an electrodeionization apparatus and an operation method thereof that can improve the boron removal rate and improve the service life of the apparatus.

  Conventionally, ultrapure water used in the field of electronic industries such as semiconductors is processed raw water with an ultrapure water production system composed of a pretreatment system, a primary pure water system, and a subsystem for processing primary pure water. It is manufactured by. In particular, in ultrapure water for the electronics industry, it may be required to suppress the boron concentration to 0.1 ppt or less, and it is desirable to reduce the boron concentration of treated water in the primary pure water system.

  This primary pure water system is not limited to the use of ultrapure water as described above, and is a general-purpose system that can be used as a pure water production apparatus for pharmaceuticals and foods without using a subsystem. As the system configuration, a system composed of a reverse osmosis membrane (RO membrane) device and an electrodeionization device having a one-stage or two-stage structure is generally used. In this primary pure water system, the RO membrane device removes silica and salts, and removes ionic and colloidal TOC. Furthermore, various other inorganic or organic anions and cations are removed with an electrodeionization exchanger. Therefore, in order to reduce the boron concentration of primary pure water, it is important to increase the boron removal rate in the electrodeionization apparatus.

  Here, the electrodeionization apparatus generally arranges a cation exchange membrane and an anion exchange membrane alternately between a cathode and an anode, and forms a partition by the cation exchange membrane and the anion exchange membrane, thereby forming a demineralization chamber and a concentration chamber. The desalting chamber and the concentrating chamber are filled with an ion exchange resin.

  In this electrodeionization apparatus, when water to be treated is passed through the desalting chamber and concentrated water is passed through the concentrating chamber, and an electric current is passed between the cathode and the anode in this state, the ion exchange resin is removed from the desalting chamber. Through the anion exchange membrane and the cation exchange membrane, ions in the water to be treated move to the concentration chamber, whereby deionized water (treated water) is obtained from the desalting chamber. Further, the concentrated drainage in which the ions flowing through the concentration chamber are concentrated is discarded or partially recycled.

The boron removal rate in the electrodeionization apparatus as described above depends on the boron concentration in the water to be treated. For example, high-performance electrodeionization such as “KCDI-UPz” (trade name) manufactured by Kurita Kogyo Co., Ltd. Even in the apparatus, it is about 99% under normal operating conditions with a current density of 300 mA / dm ² or less. Therefore, for the purpose of improving the boron removal rate of the electrodeionization apparatus, there has been an operation method for improving the ion removal rate by increasing the current supplied to the electrodeionization apparatus (increasing the current density). For example, by setting the current density of the current supplied to the electrodeionization apparatus to 500 mA / dm ² or more, boron can be removed by 99.95% or more, further 99.99% or more.

However, the electrodeionization apparatus current density 500mA / dm ² or more (in particular 800 mA / dm ² or more, further 1000 mA / dm ² or more) When operating at the tendency of the electrical resistance of the electrodeionization apparatus is increased is intensified. That is, there is a problem that if the voltage value for flowing a necessary current increases and reaches the operation limit (600 V), the subsequent current cannot be secured. Furthermore, when operating at high current density, for example less current density is 500mA / dm ² in life 4 years during operation, 800 mA / dm In ² 2 years or less, a problem that becomes less 1000 mA / dm ² in 1 year There is. On the other hand, in order to make the service life of the electrodeionization apparatus 5 years or longer, it is necessary to operate at a current density of about 420 mA / dm ² or less. There is a problem that the removal rate is only about 99.95%.

The present invention has been made in view of the above-mentioned problems, and even when operated at a high current density of 500 mA / dm ² or more, the voltage increase is small and the boron removal rate can be improved and the lifetime of the apparatus is prevented from decreasing. It is an object of the present invention to provide an electrodeionization apparatus and a method for operating the same.

  In order to achieve the above object, first, the present invention is partitioned by a cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and these cation exchange membrane and anion exchange membrane. A desalting chamber and a concentrating chamber, wherein the desalting chamber and the concentrating chamber are filled with an ion exchange resin, and the concentrated water passing means for passing concentrated water through the concentrating chamber and the desalting chamber An electric deionization device for passing deionized water that has passed through the demineralization chamber as concentrated water. At least the cation exchange membrane of the cation exchange membrane and the anion exchange membrane is a heterogeneous membrane, and the ion exchange resin filled in the desalting chamber has an anion exchange resin: cation exchange resin volume ratio of 80: 20-60. : 40 At least the cation exchange resin of the exchange resin to provide electrodeionization apparatus is obtained by pre-washed to be equal to or less than TOC elution amount 1 ppb (water flow conditions SV = 50 / h) (invention 1).

According to this invention (invention 1), even if the current (current density) supplied to the electrodeionization apparatus is increased, the increase in voltage can be suppressed and the boron removal rate can be increased. This is thought to be due to the following reasons. That is, dissociation of water (H ₂ O → H ⁺ + OH ⁻ ) occurs at the interface between the anion exchange resin and the cation exchange resin or at the interface between the anion exchange membrane and the cation exchange resin when the electrodeionization apparatus is operated. The higher the density, the more active the water dissociation. The more active the water dissociation, the more elution of the PSA (polystyrene sulfonic acid) component from the cation exchange resin. And it is estimated that the electrical resistance of an electrodeionization apparatus rises because the component with comparatively large molecular weight adheres and accumulates in an ion exchange membrane little by little among PSA components. For this reason, as the current density during operation of the electrodeionization device increases, the electrical resistance increases, and the voltage for flowing the necessary current increases.

Thus, as a result of various studies on methods for suppressing an increase in electric resistance (voltage increase), the present inventor has found that the following three means are effective. (1) The elution amount of organic substances from ion exchange resins, particularly cation exchange resins, and PSA elution quantities have a correlation, and the smaller the elution quantity of organic substances, the smaller the elution quantity of PSA. It is effective to use an exchange resin, at least a cation exchange resin having a low PSA elution, and specifically, by washing the ion exchange resin in advance, the TOC elution amount is 1 ppb or less (SV = 50 / h). Reduced water flow conditions). (2) The ratio of the cation exchange resin and the anion exchange resin in the ion exchange resin (mixed resin) filled in the electrodeionization apparatus decreases from the point of elution of the PSA component as the ratio of the anion exchange resin increases. If the amount is too large, the removal rate of the cation component decreases, so the anion exchange resin ratio is set to 80 to 60%. In addition, (3) ion exchange membranes are generally classified into homogeneous membranes and heterogeneous membranes, but there is a difference in the increase in electrical resistance of the electrodeionization apparatus due to the difference between the two, and the homogeneous membrane has a uniform surface and PSA. Since the components must pass through the membrane, the PSA component having a relatively large molecular weight is difficult to pass through and tends to accumulate, while the heterogeneous membrane has a structure in which a pulverized ion exchange resin is embedded in the base material. Therefore, even if it does not pass through the ion exchange resin, it can pass near the interface with the base material through the surface of the ion exchange resin, and PSA is unlikely to accumulate. For this reason, when an ion exchange membrane, at least a cation exchange membrane is a heterogeneous membrane, an increase in electrical resistance can be suppressed. By combining these three means, the electrodeionization apparatus can be operated with a high current density of 500 mA / dm ² or more to improve the boron removal rate, and the voltage increase with time is small. It was confirmed that the service life of can be set as long as 5 years or more. Based on these, the present invention (Invention 1) was conceived.

  In the said invention (invention 1), it is preferable that the said concentrated water flow means is a part which flows a part of deionized water which flowed through the said demineralization chamber as concentrated water by counterflow (invention 2). ).

  According to this invention (invention 2), the difference in the concentration gradient of ions in the demineralization chamber and the concentration chamber of the electrodeionization apparatus can be alleviated, so that the boron removal rate can be further improved.

  In the above inventions (Inventions 1 and 2), both the cation exchange membrane and the anion exchange membrane are heterogeneous membranes, and both the anion exchange resin and the cation exchange resin filled in the desalting chamber have a TOC elution amount of 1 ppb. It is preferably washed in advance so as to satisfy the following conditions (SV = 50 / h water flow condition) (Invention 3).

  According to this invention (Invention 3), by making both the cation exchange membrane and the anion exchange membrane heterogeneous and making both the anion exchange resin and the cation exchange resin highly washed resin, The effect of suppressing the increase (voltage increase) can be maximized.

In addition, secondly, the present invention provides a cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, a desalting chamber partitioned by the cation exchange membrane and the anion exchange membrane, and A concentrating chamber, wherein the desalting chamber and the concentrating chamber are filled with an ion exchange resin, and the concentrated water passing means for passing the condensate through the concentrating chamber and the water to be treated are passed through the desalting chamber. Means for removing deionized water by water, and passing the deionized water that has passed through the demineralization chamber as the concentrated water by the concentrated water passing means, and at least of the cation exchange membrane and the anion exchange membrane. The cation exchange membrane is a heterogeneous membrane, and the volume ratio of anion exchange resin: cation exchange resin of the ion exchange resin filled in the desalting chamber is 80: 20-60: 40, and at least of the ion exchange resins Cation exchange resin OC elution amount 1ppb following method of operating a (SV = 50 / h of water flow conditions) and a way prewashed those were electrodeionization apparatus, the current supplied to the electrodeionization apparatus 500mA / dm Provided is a method for operating an electrodeionization apparatus for passing water through the desalting chamber at a current density of ² or more (Invention 4).

According to this invention (Invention 4), with the electrodeionization apparatus configured as described above, even if the boron removal rate is kept high by operating at a current density of 500 mA / dm ² or more, the increase in voltage is suppressed. can do.

  In the said invention (invention 4), it is preferable that the said concentrated water flow means is a part which flows a part of deionized water which flowed through the said demineralization chamber as concentrated water by counterflow (invention 5). ).

  According to this invention (invention 5), the difference in ion concentration gradient between the demineralization chamber and the concentration chamber of the electrodeionization apparatus can be alleviated, so that the boron removal rate can be further improved.

  In the above inventions (Inventions 4 and 5), both the cation exchange membrane and the anion exchange membrane are heterogeneous membranes, and both the anion exchange resin and the cation exchange resin filled in the desalting chamber have a TOC elution amount of 1 ppb. It is preferable that the substrate is washed in advance so as to satisfy the following condition (SV = 50 / h water flow condition) (Invention 6).

  According to this invention (Invention 6), by making both the cation exchange membrane and the anion exchange membrane a heterogeneous membrane and making both the anion exchange resin and the cation exchange resin highly washed resin, The effect of suppressing the increase (voltage increase) can be maximized.

  According to the present invention, a highly washed ion exchange resin to be filled in the demineralization chamber of the electrodeionization apparatus is adopted, and more anion exchange resin is blended than cation exchange resin, and the ion exchange resin is not used as an ion exchange membrane. Since a homogeneous film is used, voltage rise can be suppressed even when operating at a high current density in order to maintain a high boron removal rate, and the service life of the electrodeionization apparatus can be prolonged. .

It is typical sectional drawing which shows the structure of the electrodeionization apparatus by one Embodiment of this invention. It is a systematic diagram which shows the electrodeionization apparatus of FIG.

  Hereinafter, an electrodeionization apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing the configuration of an electrodeionization apparatus according to an embodiment of the present invention. In FIG. 1, an electrodeionization apparatus 1 includes a plurality of anion exchange membranes 4 and cation exchange membranes 5 arranged alternately between electrodes (anode 2 and cathode 3), and alternately a concentration chamber 6 and a demineralization chamber 7. The desalting chamber 7 is filled with ion exchange resins (anion exchange resin and cation exchange resin) in a mixed or multi-layered manner. The concentration chamber 6, the anode chamber 8, and the cathode chamber 9 are also filled with ion exchange resin.

  In the electrodeionization apparatus 1, water passing means (not shown) for passing the treated water W through the demineralization chamber 7 and taking out the treated water (deionized water) W <b> 1, and the concentrated water W <b> 2 in the concentration chamber 6. Concentrated water passage means (not shown) for passing water is provided, and in this embodiment, the concentrated water W2 is introduced into the concentration chamber 6 from the side of the desalting chamber 7 close to the outlet of the treated water W1. At the same time, the concentrated water W2 flows out from the side close to the inlet of the desalting chamber 7, that is, the concentrated water W2 is introduced into the concentrating chamber 6 from the direction opposite to the flow direction of the treated water W in the desalting chamber 7, and the concentrated waste water W3 is discharged. It has a configuration.

  Specifically, as shown in FIG. 2, part of the treated water W <b> 1 obtained from the desalting chamber 7 is introduced into the concentration chamber 6 and the anode chamber 8. In this way, the concentrated water W2 having a reduced ion concentration is circulated using the treated water W1 as the concentrated water W2.

  In such an electrodeionization apparatus, the ratio of anion exchange resin: cation exchange resin of the ion exchange resin filled in the desalting chamber 7 is 80: 20-60: 40, preferably 80: 20-70: 30. When the proportion of the anion exchange resin exceeds 80% by volume, the elution of the PSA component derived from the cation exchange resin is reduced, but the removal rate of the cation component in the treated water W1 is lowered. On the other hand, when the proportion of the anion exchange resin is less than 60% by volume, the elution of the PSA component derived from the cation exchange resin increases, the electric resistance of the electrodeionization apparatus increases, and the voltage required for operation increases. The service life of the electrodeionization apparatus 1 is easily shortened. In addition, the ratio of the ion exchange resin may be different between the upper side (inlet side) and the lower side (outlet side) of the desalting chamber 7, and in this case, the upper side (inlet side) within the above ratio range. It is preferable to increase the ratio of the anion exchange resin.

  In addition, at least the cation exchange resin among the ion exchange resins filled in the desalting chamber 7 is previously conditioned (washed) so that the TOC elution amount is 1 ppb or less. When the TOC elution amount of the cation exchange resin exceeds 1 ppb, the elution amount of PSA resulting from the ion exchange resin increases, the electric resistance of the electrodeionization apparatus increases, the voltage required for operation increases, and thus the electrodeionization rate increases. The service life of the ion device 1 is easily shortened. In the present specification, the TOC elution amount is measured with a TOC meter (Anatel A-1000) after passing ultrapure water for 120 minutes at SV = 50 / h with respect to the amount of 2 L of ion exchange resin. This is the amount of TOC elution (increase). In this conditioning, for example, an acid cleaning process, an acid extrusion process using ultrapure water, a warm water cleaning process using warm ultrapure water, a finishing process using ultrapure water, and the like under appropriate conditions (concentration, concentration, etc.) so that the TOC elution amount is 1 ppb or less. Time and flow rate) may be performed sequentially. Note that it is preferable to use an anion exchange resin that has been conditioned (washed) in advance so that the TOC elution amount is 1 ppb or less by conditioning (washing).

  Further, the ratio of the anion exchange resin and the cation exchange resin in the ion exchange resin to be filled in the concentration chamber 6 is not particularly limited, and it is preferable that both are equivalent or the cation exchange resin is increased to some extent. The ratio of the exchange resin may be 60:40 to 50:50 in volume ratio. Furthermore, it is preferable to use the ion-exchange resin filled in the concentrating chamber 6 after conditioning as described above.

  Furthermore, at least the anion exchange membrane 4 of the anion exchange membrane 4 and the cation exchange membrane 5 as an ion exchange membrane uses a heterogeneous membrane. Here, the heterogeneous membrane refers to an ion exchange membrane formed by casting, for example, by combining a suspension of fine particles of an ion exchange resin (here, anion exchange resin) with a binder. Since this heterogeneous membrane has a structure in which a pulverized anion exchange resin is embedded in the base material, it passes through the anion exchange resin surface near the interface with the base material without passing through the anion exchange resin. Therefore, PSA accumulation is unlikely to occur, and an increase in electrical resistance can be suppressed. The cation exchange membrane 5 may be a homogeneous membrane, but similarly, a heterogeneous membrane is preferably used.

Next, an operation method of the electrodeionization apparatus 1 having the above-described configuration will be described. First, the water to be treated W such as RO treated water is treated by the electrodeionization apparatus 1. At this time, the electrodeionization apparatus 1 is operated at a current density of 500 mA / dm ² or more. When the current density is less than 500 mA / dm ² , a sufficient effect of improving the boron removal rate cannot be obtained. The operation is preferably performed at a current density of 800 mA / dm ² or more. If the current density is less than 800 mA / dm ² , it is difficult to obtain a boron removal rate exceeding 99.95%. In particular, by operating at a current density of 1000 mA / dm ² or more, a boron removal rate of 99.99% can be achieved. On the other hand, operating the electrodeionization apparatus 1 at a current density exceeding 1500 mA / dm ² not only provides an effect of improving the boron removal rate beyond that, but also increases the electric resistance value. This is not preferable because the voltage applied to the device 1 increases excessively and the life of the device is reduced. In addition, as for the water flow rate of the to-be-processed water W in the demineralization chamber 7 of the electrodeionization apparatus 1, LV = 50-200 m / h is preferable, and space velocity is SV = 50-200 / h. Furthermore, the electrodeionization apparatus 1 is preferably operated at a water recovery rate of 80 to 90%.

  Thereby, the to-be-processed water W is introduce | transduced into the desalting chamber 7, and the treated water (deionized water) W1 is obtained from the desalting chamber 7. FIG. In the present embodiment, a part of the treated water W1 is concentrated water W2 and is passed through the concentration chamber 6 in a counter-current transient manner in a direction opposite to the flow direction of the desalting chamber 7, and concentrated from the concentration chamber 6. Waste water W3 is discharged out of the system. That is, in this embodiment, the concentrating chamber 6 and the desalting chamber 7 are alternately arranged in parallel, and serves as an inlet of the concentrating chamber 6 on the extraction side of the treated water W1 in the desalting chamber 7 and the desalting chamber 7. The outlet of the concentrating chamber 6 is on the raw water inflow side. A part of the treated water (deionized water) W 1 is fed to the inlet side of the anode chamber 8, and the outflow water of the anode chamber 8 is fed to the inlet side of the cathode chamber 9. The effluent is discharged out of the system as wastewater.

  In this way, the treated water W1 is passed through the concentration chamber 6 as the concentrated water W2 in a counter-current and transient manner with respect to the desalting chamber 7, so that the concentrated water W2 in the concentration chamber 6 is closer to the desalting chamber 7 on the extraction side. Since the concentration of ions therein is low, the influence on the desalting chamber 7 due to concentration diffusion is reduced, and the ion removal rate, particularly the boron removal rate, can be dramatically increased.

  By operating the electrodeionization apparatus 1 in this manner, the boron removal rate can be increased to 99.9% or more, particularly 99.95%, and further to about 99.99%.

As mentioned above, although one Embodiment of this invention has been demonstrated with reference to an accompanying drawing, if this invention employ | adopts the predetermined structure mentioned above to the electrodeionization apparatus 1, and it drive | operates with a current density of 500 mA / dm < ² > or more. The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the present embodiment, the electrode ionization apparatus 1 can have a service life of 5 years or more and a boron removal rate of 99.99% by adopting the best mode, but the required water quality and service life can be increased. Accordingly, the current density during operation, the type of cation exchange membrane, or the conditioning conditions of the anion exchange resin can be appropriately set.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.

[Example 1]
The following were used as the electrodeionization apparatus 1 and ion exchange resin.
Electrodeionization device: KCDI-UPz (manufactured by Kurita Kogyo Co., Ltd.), as shown in FIGS. 1 and 2, a part of deionized water W1 that has passed through the desalting chamber 7 is concentrated as concentrated water W2 in a counterflow Adopting a method of passing water through the chamber 6 Ion exchange resin: KR-UM1 (manufactured by Kurita Kogyo Co., Ltd.), an anion that has been conditioned so that the TOC elution amount is 1 ppb or less (SV = 50 / h water passing condition) Mixed resin of exchange resin and cation exchange resin

  In the electrodeionization apparatus 1 described above, the conditioned ion exchange resin is filled with 80% by volume of the anion exchange resin and 20% by volume of the cation exchange resin in the upper half (inlet side) of the desalting chamber 7, and the anion in the lower area. It filled so that it might become 60 volume% of exchange resins, and 40 volume% of cation exchange resins, and it filled so that it might become 60 volume% of anion exchange resins, and 40 volume% of cation exchange resins in the concentration chamber 6. Furthermore, the electrodeionization apparatus 1 was configured using heterogeneous membranes as the anion exchange membrane 4 and the cation exchange membrane 5.

The city water (raw water) in Yoshida-cho, Kashihara-gun, Shizuoka Prefecture was treated with a pretreatment system consisting of an agglomeration / pressure flotation device, a filtration device and an activated carbon tower, and then treated with a two-stage RO membrane device. The silica concentration of the two-stage RO treated water (treated water) W was 1 ppb or less, and the boron concentration was 1 to 5 ppb. Subsequently, the treated water W was passed through the above-described electrodeionization apparatus 1 (KCDI-UPz manufactured by Kurita Kogyo Co., Ltd.) at a flow rate of 15 m ³ / h and operated at a current density of 1000 mA / dm ² . The SV in this electrodeionization apparatus was 100 / h, and the water recovery rate was 85%.

  When the operation of the electrodeionization apparatus was continued, the initial voltage was 300V, whereas the voltage after five years of operation increased to 500V, but the boron removal rate of the treated water W1 of the electrodeionization apparatus was 99. The electrodeionization apparatus of Example 1 had a service life of 5 years or more.

[Comparative Example 1]
In Example 1, a resin that was not conditioned (TOC elution amount of about 10 ppb, hereinafter the same) was used to fill the desalting chamber 7 and the concentration chamber 6 with 50% by volume of anion exchange resin and 50% by volume of cation exchange resin. Furthermore, the electrodeionization apparatus 1 was configured using homogeneous membranes as the anion exchange membrane 4 and the cation exchange membrane 5. When the treated water W was treated with the electrodeionization apparatus 1 under the same operating conditions as in Example 1, the initial voltage was 300 V, whereas the voltage after one year of operation reached an operating limit of 600 V, which is a comparison. The service life of the electrodeionization apparatus of Example 1 was about 1 year.

[Comparative Example 2]
In Example 1, a resin that was not conditioned was used to fill the demineralization chamber 7 and the concentration chamber 6 with 50% by volume of anion exchange resin and 50% by volume of cation exchange resin, thereby configuring the electrodeionization apparatus 1. The treated water W was treated with this electrodeionization apparatus 1 under the same operating conditions as in Example 1. The initial voltage was 300V, whereas the voltage after two years of operation reached the operating limit of 600V. The service life of the electrodeionization apparatus of Example 2 was about 2 years.

[Comparative Example 3]
In Example 1, the electrodeionization apparatus 1 was comprised similarly except having used resin which was not conditioned. When the treated water W was treated with this electrodeionization apparatus 1 under the same operating conditions as in Example 1, the initial voltage was 300V, whereas the voltage after three years of operation reached an operating limit of 600V. The service life of the electrodeionization apparatus of Example 3 was about 3 years.

[Comparative Example 4]
In Example 1, the electrodeionization apparatus 1 was configured in the same manner except that the demineralization chamber 7 and the concentration chamber 6 were filled with 50% by volume of the anion exchange resin and 50% by volume of the cation exchange resin. When the treated water W was treated with this electrodeionization apparatus 1 under the same operating conditions as in Example 1, the initial voltage was 300V, whereas the voltage after 4 years of operation reached an operating limit of 600V. The service life of the electrodeionization apparatus of Example 4 was about 4 years.

1 Electrodeionization equipment 2 Anode (electrode)
3 Cathode (electrode)
4 Anion exchange membrane (ion exchange membrane)
5 Cation exchange membrane (ion exchange membrane)
6 Concentration chamber 7 Desalination chamber 8 Anode chamber 9 Cathode chamber W Treated water W1 Treated water (deionized water)
W2 Concentrated water W3 Concentrated drainage

Claims (6)

A cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and a desalting chamber and a concentrating chamber defined by the cation exchange membrane and the anion exchange membrane, A means for passing concentrated water through the concentration chamber, and means for extracting deionized water by passing water to be treated into the demineralization chamber. The deionized water that the deionized water that has passed through the demineralization chamber passes as concentrated water,
At least the cation exchange membrane of the cation exchange membrane and the anion exchange membrane is a heterogeneous membrane,
The ion exchange resin filled in the desalting chamber has an anion exchange resin: cation exchange resin volume ratio of 80:20 to 60:40,
An electrodeionization apparatus in which at least the cation exchange resin of the ion exchange resin is washed in advance so as to have a TOC elution amount of 1 ppb or less (SV = 50 / h water flow condition).   2. The electrodeionization apparatus according to claim 1, wherein the concentrated water flow means passes a part of deionized water that has passed through the demineralization chamber as concentrated water in a counterflow.   Both the cation exchange membrane and the anion exchange membrane are heterogeneous membranes, and both the anion exchange resin and the cation exchange resin filled in the desalting chamber have a TOC elution amount of 1 ppb or less (SV = 50 / h water flow condition) The electrodeionization apparatus according to claim 1 or 2, which has been washed in advance so that A cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and a desalting chamber and a concentrating chamber defined by the cation exchange membrane and the anion exchange membrane, A means for passing concentrated water through the concentration chamber, and means for extracting deionized water by passing water to be treated into the demineralization chamber. The deionized water that has passed through the demineralization chamber is passed as concentrated water, and at least the cation exchange membrane and the anion exchange membrane are heterogeneous membranes. The volume ratio of the anion exchange resin to the cation exchange resin of the ion exchange resin filled in the desalting chamber is 80:20 to 60:40, and at least the cation exchange resin of the ion exchange resin has a TOC elution amount of 1 ppb or more. A (SV = 50 / water flow conditions h) and so as to method of operating an electrodeionization apparatus is obtained by pre-washed,
The operation method of the electrodeionization apparatus which water-processes to the said demineralization chamber as the electric current supplied to the said electrodeionization apparatus as a current density of 500 mA / dm < ² > or more.   The operation method of the electrodeionization apparatus according to claim 4, wherein the concentrated water flow means passes a part of deionized water that has passed through the demineralization chamber as concentrated water in a counterflow.   Both the cation exchange membrane and the anion exchange membrane are heterogeneous membranes, and both the anion exchange resin and the cation exchange resin filled in the desalting chamber have a TOC elution amount of 1 ppb or less (SV = 50 / h water flow condition) The method for operating the electrodeionization apparatus according to claim 4 or 5, wherein the electrodeionization apparatus has been previously cleaned so that

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