JP2015080765A - Pure water production apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively exhibit treatment performance of an electric deionized water production device in a pure water production apparatus formed by combining RO membrane separation devices, a decarbonation device, and the electric deionized water production device.SOLUTION: A pure water production apparatus 1, which produces pure water by sequential treatment of water to be treated, includes a plurality of reverse osmosis membrane separation devices 2, 4, a decarbonation device 3, and an electric deionized water production device 10. The plurality of reverse osmosis membrane separation devices 2, 4 comprises a first reverse osmosis membrane separation device 2 and a second reverse osmosis membrane separation device 4. The decarbonation device 3 is serially connected to the first and second reverse osmosis membrane separation devices 2, 4 between them. The electric deionized water production device 10 is connected to the downstream side of the plurality of reverse osmosis membrane separation devices 2, 4 with respect to the flow direction of the water to be treated.

Description

  The present invention relates to a pure water production apparatus.

  As a method for producing pure water from raw water such as industrial water, well water, city water, etc., a method using a reverse osmosis (RO) membrane separator is known. In this method, permeated water (pure water) is obtained by subjecting raw water to pretreatment such as turbidity and dechlorination and then passing the water through an RO membrane. However, with the method using only the RO membrane separator, it is difficult to produce high-grade pure water required in the field of manufacturing semiconductors and pharmaceuticals. Therefore, in such a manufacturing field, a pure water production apparatus is used that produces deionized water (pure water) by further passing permeated water separated by the RO membrane through an ion exchanger. That is, a pure water production apparatus in which an RO membrane separation apparatus and a deionized water production apparatus are combined is used.

  In recent years, an electrical deionized water production apparatus that does not require regeneration of an ion exchanger with a chemical such as acid or alkali has been put to practical use as a deionized water production apparatus. In this apparatus, when the ion exchange group of the ion exchanger is saturated and the desalting performance is lowered, in order to replace cations and anions adsorbed on the ion exchange group with hydrogen ions or hydroxide ions, acid or alkali is used. There is no need to use drugs. Therefore, by using such an electric deionized water production apparatus for the above-described pure water production apparatus, it is possible to produce pure water with higher purity while suppressing the amount of chemicals used.

  On the other hand, the electric deionized water production apparatus generally has a problem that the performance of removing weakly acidic components such as silica and carbonic acid is low. For example, if silica or carbonic acid is present at a very high concentration in the water to be treated, they may not be sufficiently removed and leak into the treated water (deionized water). Therefore, depending on the quality of raw water, it is necessary to reduce the load on the electric deionized water production apparatus. Therefore, many pure water production systems employ a configuration in which a plurality of RO membrane separators are connected to the upstream side of the electrical deionized water production system, and decarbonation means for decarboxylating the water to be treated is connected. (For example, refer to Patent Document 1).

  By the way, the decarbonation means has a characteristic that it is difficult to remove the carbonic acid component unless the water to be treated is acidic. In addition, the decarbonation means has a demerit that slime is likely to propagate when water containing a high concentration of total organic carbon (TOC) is treated. From this point of view, in a pure water production apparatus that combines a plurality of RO membrane separators, decarbonation means, and electric deionized water production apparatus, dewatering is performed downstream of the plurality of RO membrane separation apparatuses connected in series. A structure in which a carbonic acid means is connected and an electric deionized water production apparatus is connected to the downstream side is suitably used. The permeated water separated by the RO membrane separator contains free carbonic acid as a main component. Therefore, according to the above-described configuration, the water to be treated that is inclined to be acidic by passing through a plurality of RO membrane separation devices can be supplied to the decarbonation means. Further, since the TOC is also sufficiently removed by the plurality of RO membrane separation devices, the problem that slime is generated in the decarbonation means is also avoided. Furthermore, since the amount of treated water in the decarbonation means is small, it is possible to realize cost reduction by downsizing.

JP 2004-167423 A

  Thus, in the pure water manufacturing apparatus which combined several RO membrane separation apparatus, the decarbonation means, and the electrical deionized water manufacturing apparatus, several RO membrane separation apparatus, a decarbonation means, and an electrical deionized water manufacturing apparatus A configuration in which and are connected in this order is preferably used. However, in such a configuration, as described above, the characteristics and problems of the decarbonation means are considered, but the treatment performance of the electric deionized water production apparatus is not considered at all. For this reason, the treatment performance of the electric deionized water production apparatus cannot be effectively exhibited, and a desired treated water quality may not be obtained.

  Therefore, an object of the present invention is to effectively demonstrate the processing performance of an electric deionized water production apparatus in a pure water production apparatus that combines a plurality of RO membrane separation devices, a decarbonation apparatus, and an electric deionized water production apparatus. It is to provide a configuration to be made.

  In order to achieve the above-described object, a pure water production apparatus of the present invention is a pure water production apparatus for producing pure water by sequentially treating water to be treated, which is a first reverse osmosis membrane separation device and a second one. Between the plurality of reverse osmosis membrane separation devices connected in series and the first reverse osmosis membrane separation device and the second reverse osmosis membrane separation device. A decarboxylation device connected in series to the osmosis membrane separation device and the second reverse osmosis membrane separation device, and an electric type connected to the downstream side of the plurality of reverse osmosis membrane separation devices with respect to the flow direction of the water to be treated A deionized water production apparatus.

  As mentioned above, according to this invention, in the pure water manufacturing apparatus which combined the several RO membrane separator, the decarbonation apparatus, and the electrical deionized water manufacturing apparatus, the processing performance of an electrical deionized water manufacturing apparatus is exhibited effectively. Can be made.

It is a block diagram which shows the structure of the pure water manufacturing apparatus by the 1st Embodiment of this invention. It is the schematic which shows the structure of the electrical deionized water manufacturing apparatus of this embodiment. It is the schematic which shows the structure of the electrical deionized water manufacturing apparatus by the 2nd Embodiment of this invention. It is the schematic which shows the structure of the electrical deionized water manufacturing apparatus by the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
The structure of the pure water manufacturing apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a block diagram showing the configuration of the pure water production apparatus of this embodiment.

  The pure water production apparatus 1 includes two reverse osmosis (RO) membrane separation apparatuses 2 and 4, a decarboxylation apparatus 3, and an electric deionized water production apparatus 10. In the present embodiment, the first RO membrane separation device 2, the decarboxylation device 3, the second RO membrane separation device 4, and the electric deionized water production device 10 are arranged in the direction of the water to be treated. Arranged in order. That is, the pure water production apparatus 1 is connected to the first RO membrane separation device 2, the decarboxylation device 3 connected to the downstream side of the first RO membrane separation device 2, and the downstream side of the decarbonation device 3. The second RO membrane separation device 4 and the electric deionized water production device 10 connected to the downstream side of the second RO membrane separation device 4 are provided. Furthermore, the pure water production apparatus 1 has a pretreatment apparatus (not shown) that is connected to the upstream side of the first RO membrane separation apparatus 2 and performs turbidity, dechlorination, and the like.

  In the first RO membrane separation device 2, raw water pretreated by a pretreatment device flows as treated water. The first RO membrane separation device 2 has an RO membrane that separates the water to be treated into concentrated water containing impurities and permeated water from which impurities have been removed.

  Permeated water separated by the first RO membrane separation device 2 flows into the decarbonation device 3 as water to be treated. The decarboxylation device 3 has a function of decarboxylating the water to be treated and removing carbon dioxide contained in the water to be treated. Examples of such a decarboxylation device 3 include a membrane deaeration device, a decarbonation tower, and the like, and a membrane deaeration device is preferably used.

  The water decarboxylated by the decarboxylation device 3 flows into the second RO membrane separation device 4 as the water to be treated. The second RO membrane separation device 4 has an RO membrane that separates the water to be treated into concentrated water containing impurities and permeated water from which impurities have been removed.

  The permeated water separated by the second RO membrane separation device 4 flows into the electric deionized water production apparatus 10 as the water to be treated. The electric deionized water production apparatus 10 is a combination of electrophoresis and electrodialysis, and simultaneously performs deionization (desalting) treatment of water to be treated with an ion exchanger and regeneration treatment of the ion exchanger. Device.

  Here, the configuration of the electric deionized water production apparatus of the present embodiment will be described. FIG. 2 is a schematic diagram showing the configuration of the electric deionized water production apparatus of the present embodiment.

  The electric deionized water production apparatus 10 includes an anode chamber E1 including an anode 11, a cathode chamber E2 including a cathode 12, a demineralization chamber D provided between the anode chamber E1 and the cathode chamber E2, A pair of concentrating chambers C1, C2 located on both sides of the desalting chamber D, on the anode 11 side of the desalting chamber D, and an anode side concentrating chamber C1 adjacent to the desalting chamber D via the anion exchange membrane a1; On the cathode 12 side of the desalting chamber D, a pair of concentrating chambers C1, C2 including the desalting chamber D and the adjacent cathode-side concentrating chamber C2 via the cation exchange membrane c1 are provided. The anode enrichment chamber C1 is adjacent to the anode chamber E1 via the cation exchange membrane c2, and the cathode enrichment chamber C2 is adjacent to the cathode chamber E2 via the anion exchange membrane a2.

  The desalting chamber D is filled with a mixture of a cation exchanger and an anion exchanger. That is, the cation exchanger and the anion exchanger are packed in a so-called mixed bed form. Examples of the cation exchanger include a cation exchange resin, a cation exchange fiber, and a monolithic porous cation exchanger, and the most versatile cation exchange resin is preferably used. Examples of the cation exchanger include weakly acidic cation exchangers and strongly acidic cation exchangers. Examples of the anion exchanger include anion exchange resins, anion exchange fibers, and monolithic porous anion exchangers, and the most general anion exchange resin is preferably used. A flow path from the second RO membrane separation device 4 is connected to the desalting chamber D, and the permeated water separated by the second RO membrane separation device 4 flows therein.

  The anode-side enrichment chamber C1 and the cathode-side enrichment chamber C2 are provided for taking in the anion component and the cation component discharged from the desalting chamber D and releasing them out of the system. In the present embodiment, as the concentrated water, a part of the permeated water flows into each of the concentration chambers C1 and C2. The concentrated water is not limited to this, and can be supplied by another supply line. In order to suppress the electric resistance of the electric deionized water production apparatus 1, each of the concentrating chambers C1 and C2 may be filled with an ion exchanger.

  The anode chamber E1 accommodates an anode 11 made of a metal net or plate. The cathode chamber E2 contains a cathode 12 made of a metal net or plate. A part of the permeated water flows into the anode chamber E1 and the cathode chamber E2 as electrode water. In order to suppress the electric resistance of the electric deionized water production apparatus 1, it is preferable that the anode chamber E1 and the cathode chamber E2 are filled with an ion exchanger.

  Next, the operation of the electric deionized water production apparatus of this embodiment will be briefly described with reference to FIG.

  A part of the permeated water from the second RO membrane separation device 4 is supplied in advance to the anode side concentration chamber C1 and the cathode side concentration chamber C2 as concentrated water. Similarly, a part of the permeated water is supplied to the anode chamber E1 and the cathode chamber E2 as electrode water. A predetermined voltage is applied between the anode 11 and the cathode 12.

  In this state, permeated water from the second RO membrane separation device 4 is caused to flow into the desalting chamber D as water to be treated. When the water to be treated passes through the desalting chamber D, the cation component and the anion component in the water to be treated are adsorbed and removed by the cation exchanger and the anion exchanger filled in the desalting chamber D, respectively. Thus, the water to be treated from which the cation component and the anion component have been removed is discharged out of the electric deionized water production apparatus 1 as treated water (pure water).

On the other hand, in the desalting chamber D, a water dissociation reaction in which water is dissociated into hydrogen ions (H ⁺ ) and hydroxide ions (OH ⁻ ) proceeds continuously. H ⁺ is exchanged with a cation component adsorbed on the cation exchanger, and OH ⁻ is exchanged with an anion component adsorbed on the anion exchanger. Thus, the cation exchanger and the anion exchanger filled in the desalting chamber D are regenerated.

  The cation component liberated from the cation exchanger in the desalting chamber D is attracted to the cathode 12 side by the potential difference between the anode 11 and the cathode 12, passes through the cation exchange membrane c1, and moves to the cathode concentration chamber C2. The cation component that has moved to the cathode side concentrating chamber C2 is taken into the permeate (concentrated water) supplied to the cathode side concentrating chamber C2, and is discharged out of the electric deionized water production apparatus 1 together with the concentrated water. The anion component liberated from the anion exchanger in the desalting chamber D is attracted to the anode side 11 by the potential difference between the anode 11 and the cathode 12, passes through the anion exchange membrane a1, and moves to the anode concentration chamber C1. The anion component that has moved to the anode side concentrating chamber C1 is taken into the permeated water (concentrated water) supplied to the anode side concentrating chamber C1, and is discharged out of the electric deionized water production apparatus 1 together with the concentrated water.

  As described above, in the pure water production apparatus 1 of the present embodiment, the first RO membrane separation device 2, the decarboxylation device 3, and the second RO membrane separation device 4 are connected in series in this order, and downstream thereof. An electric deionized water production apparatus 10 is connected to the side. By arranging each device in this way, the treatment performance of the electrical deionized water production device can be effectively exhibited as shown in the examples described later.

  In the above-described embodiment, two RO membrane separation devices are provided on the upstream side of the electric deionized water production device. For example, depending on the amount and type of impurities contained in the water to be treated. Three or more RO membrane separation devices may be provided. Even in that case, three or more RO membrane separators are connected in series, and the decarboxylation device is connected in series between two RO membrane separators among the three or more RO membrane separators. It is preferable that Further, from the viewpoint of reducing the amount of treated water, the decarboxylation device is more preferably disposed between the most downstream RO membrane separation device and the next downstream RO membrane separation device.

  Further, in the above-described embodiment, the electric deionized water production apparatus is provided with only one demineralization chamber, but two or more demineralization chambers may be provided. In this case, the desalting chamber and the concentrating chamber are provided alternately via a cation exchange membrane or an anion exchange membrane, the concentrating chamber located closest to the anode side is adjacent to the anode chamber, and the concentrating chamber located closest to the cathode side. Will be adjacent to the cathode chamber. On the other hand, the concentration chamber adjacent to the anode chamber is omitted, the anode chamber and the desalination chamber are adjacent, or the concentration chamber adjacent to the cathode chamber is omitted, and the cathode chamber and the desalination chamber are adjacent. You can also In this case, the anode chamber and the cathode chamber also serve as the concentration chamber, that is, ionic components in the water to be treated removed in the desalting chamber adjacent to the anode chamber or the cathode chamber move to the anode chamber or the cathode chamber. As a result, it is discharged to the outside together with the electrode water. Such a configuration is applicable regardless of the number of desalting chambers, and is also applicable to the configuration shown in FIG. 2 in which only one desalting chamber is provided. In any case, each desalting chamber is located between the anode and the cathode, and is partitioned by the anion exchange membrane on the anode side and the cation exchange membrane on the cathode side.

(Second Embodiment)
Next, the structure of the pure water manufacturing apparatus by the 2nd Embodiment of this invention is demonstrated. FIG. 3 is a diagram schematically showing the configuration of the electric deionized water production apparatus of the present embodiment.

  This embodiment is a modification of the first embodiment, and is a modification in which the configuration of the demineralization chamber in the electric deionized water production apparatus is changed. Therefore, the pure water manufacturing apparatus of this embodiment has the same configuration as that of the first embodiment except for the configuration of the demineralization chamber of the electric deionized water manufacturing apparatus. In the following, the same components as those in the first embodiment are denoted by the same reference numerals in the drawings, description thereof is omitted, and only components different from those in the first embodiment are described.

  In the present embodiment, the desalting chamber D is filled with a cation exchanger CE and an anion exchanger AE in a double bed form. Specifically, the desalination chamber D is divided into three regions along the flow direction of the water to be treated, and the downstream and upstream regions are filled with anion exchanger AE in the form of a single bed. The region is filled with a cation exchanger CE in a single bed form. Accordingly, the water to be treated flowing into the desalting chamber D passes through the anion exchanger AE, the cation exchanger CE, and the anion exchanger AE in this order.

  By the way, when ion exchangers with different signs are stacked along the flow direction of the water to be treated in the desalination chamber as in this embodiment, a difference occurs in the electric resistance of each layer, and the current flowing through each layer There may be non-negligible bias in quantity. Such drift can occur even when ion exchangers with different filling forms are stacked along the flow direction of the water to be treated, but in general, the removal performance of ion components in the desalination chamber Leads to lowering. However, in this embodiment, by generating such a drift in the demineralization chamber D, the electric deionized water production apparatus 10 can be compared with the first embodiment, as shown in Examples described later. Processing performance can be further improved.

  The number of ion exchangers stacked in the desalting chamber, the stacking order, and the filling form of the ion exchangers filled in each region are not limited to the illustrated examples, but the purpose, application, and required performance to be used. It can be changed as appropriate. That is, the demineralization chamber only needs to be partitioned into a plurality of regions along the flow direction of the water to be treated, and each region so that the water to be treated flowing into the desalting chamber sequentially passes through different ion exchangers. May be filled with at least one of a cation exchanger and an anion exchanger. Therefore, in the illustrated example, the desalination chamber D is divided into three regions along the flow direction of the water to be treated, but may be divided into two regions. The anion exchanger may be filled in a single bed form, and the downstream region may be filled with a cation exchanger and an anion exchanger in a mixed bed form.

(Third embodiment)
Next, the structure of the pure water manufacturing apparatus by the 3rd Embodiment of this invention is demonstrated. FIG. 4 is a diagram schematically showing the configuration of the electric deionized water production apparatus of the present embodiment.

  As in the second embodiment, the present embodiment is a modification of the first embodiment, and is a modification in which the configuration of the demineralization chamber in the electric deionized water production apparatus is changed. Therefore, the pure water manufacturing apparatus of this embodiment has the same configuration as that of the first embodiment (and the second embodiment) except for the configuration of the demineralization chamber of the electric deionized water manufacturing apparatus. In the following, the same components as those in the first embodiment are denoted by the same reference numerals in the drawings, description thereof is omitted, and only components different from those in the first embodiment are described.

  In the present embodiment, the desalting chamber D has a first small desalting chamber D1 adjacent to the cation exchange membrane c1 and a second small desalting chamber D2 adjacent to the anion exchange membrane a1. . The first small desalting chamber D1 and the second small desalting chamber D2 are adjacent to each other via the intermediate ion exchange membrane m and form a series flow path.

  The first small desalting chamber D1 is filled with the anion exchanger AE in a single bed form. The second small desalting chamber D2 is filled with a cation exchanger CE and an anion exchanger AE in a double bed form. Specifically, the second small desalting chamber D2 is divided into two regions along the flow direction of the water to be treated, and the upstream region is filled with the cation exchanger CE in the form of a single bed. In the region on the side, the anion exchanger AE is filled in a single bed form. Accordingly, in the present embodiment, the water to be treated that flows into the desalting chamber D passes through the anion exchanger AE, the cation exchanger CE, and the anion exchanger AE in this order.

  The intermediate ion exchange membrane m takes into consideration the quality of the water to be treated, the water quality required for deionized water, the type of ion exchanger filled in the first small demineralization chamber D1 or the second small demineralization chamber D2, and the like. Can be selected. The intermediate ion exchange membrane m may be a single membrane of an anion exchange membrane or a cation exchange membrane, or may be a composite membrane having both an anion exchange membrane and a cation exchange membrane.

  In this embodiment, after the desalting chamber D is divided into a first small desalting chamber D1 and a second small desalting chamber D2, the above-described drift is generated in the second small desalting chamber D2. ing. Such a configuration can further improve the processing performance of the electrical deionized water production apparatus 10 as compared to the second embodiment, as shown in the examples described later.

  When the desalting chamber is divided into two small desalting chambers as in this embodiment, the filling mode of the ion exchanger filled in each small desalting chamber is limited to the illustrated example. It can be changed as appropriate according to the purpose and application of use, and the required performance. That is, the first small desalting chamber is filled with at least an anion exchanger and the second small desalting chamber is at least filled so that the water to be treated flowing into the desalting chamber sequentially passes through different ion exchangers. What is necessary is just to be filled with a cation exchanger. Therefore, in the illustrated example, the second small desalting chamber D2 is filled with the cation exchanger CE and the anion exchanger AE in a double bed form, but may be filled in a mixed bed form.

  Further, in the illustrated example, the first small desalting chamber D1 and the second small desalting chamber D2 are configured such that the water to be treated is divided into the first small desalting chamber D1 and the second small desalting chamber D2. Although they are connected so as to pass through in this order, the order of water flow may be reversed. Therefore, in that case, the first small desalting chamber is filled with the cation exchanger and the anion exchanger in a double bed form or a mixed bed form, and the second small desalting chamber has a single cation exchanger. It may be filled in a floor form.

  Next, the present invention will be described in more detail with reference to specific examples.

(Example 1)
In this example, the pure water production apparatus according to the first embodiment was used for 1000 hours of operation, and the quality of treated water (treated water specific resistance) was measured. The quality of the water to be treated supplied to the pure water production apparatus has a conductivity of 150 to 200 μS / cm and a free carbonic acid concentration (CO ₂ content) of 10 to 20 mg / L.

  Both the first RO membrane separation device and the second RO membrane separation device use a RO membrane (product number: ES-20) manufactured by Nitto Denko Corporation, and the recovery rate (permeate water) of the first RO membrane separation device. The ratio of the flow rate of the permeated water to the sum of the flow rate of the concentrated waste water and the flow rate of the concentrated waste water was 70%, and the recovery rate of the second RO membrane separation device was 90%.

  A membrane deaerator was used as the decarboxylation device, “Lixel (registered trademark) X50” manufactured by Polypore Co., Ltd. was used as the deaeration membrane, and high-purity air was used as the sweep gas.

  As the electric deionized water production apparatus, an electric deionized water production apparatus provided with three demineralization chambers was used. The mixing ratio of the cation exchanger and the anion exchanger in each desalting chamber is 1: 1.

(Example 2)
In this example, measurements were performed under the same conditions as in Example 1 using the pure water production apparatus according to the second embodiment. That is, the pure water production apparatus of the present embodiment is the same as the pure water production apparatus of Embodiment 1 except for the configuration of the demineralization chamber of the electric deionized water production apparatus. Also in this example, an electrical deionized water production apparatus provided with three demineralization chambers was used as the electrical deionized water production apparatus. The lamination ratio (volume ratio) of the cation exchanger, the anion exchanger, and the cation exchanger in each desalting chamber is 1: 1: 1.

(Example 3)
In this example, measurements were performed under the same conditions as in Example 1 using the pure water production apparatus according to the third embodiment. That is, the pure water production apparatus of the present embodiment is the same as the pure water production apparatus of Examples 1 and 2 except for the configuration of the demineralization chamber of the electric deionized water production apparatus. Also in this example, an electrical deionized water production apparatus provided with three demineralization chambers was used as the electrical deionized water production apparatus.

(Comparative Example 1)
In this comparative example, the measurement was performed under the same conditions as in Example 1 except that the passage order of the water to be treated was changed. Specifically, in the pure water production apparatus of this comparative example, after the water to be treated passes through the first RO membrane separation device, the second RO membrane separation device, and the decarboxylation device in this order, This is different from the pure water production apparatus of Example 1 in that it flows into the deionized water production apparatus.

(Comparative Example 2)
In this comparative example, the measurement was performed under the same conditions as in Example 2 except that the passage order of the water to be treated was changed in the same manner as in Comparative Example 1.

(Comparative Example 3)
In this comparative example, the measurement was performed under the same conditions as in Example 3 except that the passage order of the water to be treated was changed in the same manner as in Comparative Example 1.

(Comparative Example 4)
In this comparative example, the measurement was performed under the same conditions as in Example 1 except that the electric deionized water production apparatus was replaced with an ion exchange apparatus. As a filler for the ion exchange device, a cation exchanger and an anion exchanger packed in a mixed bed form were used.

(Comparative Example 5)
In this comparative example, the measurement was performed under the same conditions as in Comparative Example 4 except that the passage order of the water to be treated was changed. Specifically, in the pure water production apparatus of this comparative example, after the treated water passes through the first RO membrane separation device, the second RO membrane separation device, and the decarboxylation device in this order, It differs from the pure water production apparatus of Comparative Example 4 in that it flows into the exchange apparatus.

  Table 1 shows the measurement results in Examples 1 to 3 and Comparative Examples 1 to 5. In addition, the specific resistance increase rate in Table 1 represented the increase in the treated water specific resistance of Examples 1-3 and Comparative Example 4 with respect to the treated water specific resistance of the corresponding Comparative Examples 1-3, 5 as a percentage. Is.

  In Examples 1 to 3, it was confirmed that better treated water quality was obtained as compared with the corresponding Comparative Examples 1 to 3. This is because the treated water supplied to the electrical deionized water production apparatus is the first RO membrane separation device, the second RO membrane separation device, and the decarbonation device in this order in Comparative Examples 1 to 3. On the other hand, in Examples 1-3, it is thought that it is an effect by passing a 1st RO membrane separator, a decarboxylation apparatus, and a 2nd RO membrane separator in this order. Such an effect is considered to be a unique effect in the case of the electric deionized water production apparatus, since almost no change was seen in the quality of treated water between Comparative Example 4 and Comparative Example 5.

  Moreover, in Example 2 and Example 3, compared with Example 1, a favorable result was obtained regarding the specific resistance increase rate. This is considered to be due to the fact that the water to be treated that has flowed into the desalting chamber alternately passes through the cation exchanger and the anion exchanger, that is, the occurrence of drift in the desalting chamber. On the other hand, when Example 2 and Example 3 are compared, better results are obtained in Example 3. In Example 3, in addition to the occurrence of the above-mentioned drift, This is probably because the desalting chamber is divided into two small desalting chambers.

DESCRIPTION OF SYMBOLS 1 Pure water manufacturing apparatus 2 1st RO membrane separation apparatus 3 Decarbonation apparatus 4 2nd RO membrane separation apparatus 10 Electric deionized water manufacturing apparatus 11 Anode 12 Cathode D Desalination chamber D1 1st small desalination chamber D2 Second small desalination chamber C1 Anode-side enrichment chamber C2 Cathode-side enrichment chamber E1 Anode chamber E2 Cathode chamber a1, a2 Anion exchange membrane c1, c2 Cation exchange membrane m Intermediate ion exchange membrane

Claims (9)

A pure water production apparatus for producing pure water by sequentially treating water to be treated,
A plurality of reverse osmosis membrane separation devices connected in series, including a first reverse osmosis membrane separation device and a second reverse osmosis membrane separation device;
Between the first reverse osmosis membrane separation device and the second reverse osmosis membrane separation device, the first reverse osmosis membrane separation device and the second reverse osmosis membrane separation device are connected in series. A decarboxylation device;
An electrical deionized water production device connected to the downstream side of the plurality of reverse osmosis membrane separation devices with respect to the flow direction of the water to be treated;
A pure water production apparatus having:   The electric deionized water production apparatus is a demineralization chamber located between an anode and a cathode and partitioned by the anion exchange membrane on the anode side and the cation exchange membrane on the cathode side, and comprising a cation exchanger The apparatus for producing pure water according to claim 1, comprising a desalting chamber filled with an anion exchanger.   The device for producing pure water according to claim 2, wherein the desalting chamber is filled with the cation exchanger and the anion exchanger in a mixed bed form.   The desalination chamber has a plurality of regions partitioned along the flow direction of the water to be treated, and each region is filled with the cation exchanger or the anion exchanger in a single bed form, Or the pure water manufacturing apparatus of Claim 2 with which the said cation exchanger and the said anion exchanger are filled with the mixed bed form. The desalting chamber has three or more regions, and each region is filled with the cation exchanger or the anion exchanger in a single bed form,
The pure water production apparatus according to claim 4, wherein the region filled with the cation exchanger and the region filled with the anion exchanger are alternately arranged along the flow direction.   The desalting chamber is adjacent to the anion exchange membrane, and is adjacent to the first small desalting chamber filled with at least the anion exchanger, the cation exchange membrane, and the first ion exchange membrane through the intermediate ion exchange membrane. A second small desalting chamber adjacent to one small desalting chamber and filled with at least the cation exchanger and forming a series flow path with the first small desalting chamber. The pure water manufacturing apparatus of description.   One small desalting chamber is filled with the cation exchanger and the anion exchanger, and the other small desalting chamber is filled with the cation exchanger or the anion exchanger in a single bed form. The pure water manufacturing apparatus according to claim 6.   The one small desalination chamber has a plurality of regions partitioned along the flow direction of the water to be treated, and each region is filled with the cation exchanger or the anion exchanger in a single bed form. The pure water production apparatus according to claim 7, wherein the cation exchanger and the anion exchanger are packed in a mixed bed form.   The one small desalination chamber has two regions, and the one region is filled with the cation exchanger in a single bed form, and the other region is filled with the anion exchanger. The device for producing pure water according to claim 8, which is filled in a form.

Images