WO2020045061A1

WO2020045061A1 - Pure water production system and pure water production method

Info

Publication number: WO2020045061A1
Application number: PCT/JP2019/031658
Authority: WO
Inventors: 真充飯山; 洋木本
Original assignee: 野村マイクロ・サイエンス株式会社
Priority date: 2018-08-28
Filing date: 2019-08-09
Publication date: 2020-03-05
Also published as: KR102708851B1; CN112424128A; JPWO2020045061A1; JP7246399B2; CN112424128B; KR20210044187A

Abstract

The present invention provides a pure water production system and a pure water production method, which are capable of stably producing pure water of high water quality for a long period of time. A pure water production system which is provided with a reverse osmosis membrane device, an ultraviolet oxidation device, an electric deionization device and a treated water pipe that sequentially connects these devices in this order. This pure water production system is characterized in that: the electric deionization device comprises a cation exchange membrane and an anion exchange membrane, which are alternately arranged, a concentration chamber and a desalting chamber, which are alternately arranged between the cation exchange membrane and the anion exchange membrane, and a pair of electrode chambers which are arranged outside the cation exchange membrane and the anion exchange membrane; the treated water pipe is connected to the electric deionization device in such a manner that the treated water of the ultraviolet oxidation device is supplied to at least the desalting chamber of the electric deionization device; and this pure water production system is provided with a first bypass pipe which supplies the permeated water of the reverse osmosis membrane device to the electrode chambers of the electric deionization device without the intermediary of the ultraviolet oxidation device.

Description

Pure water production system and pure water production method

The present invention relates to a pure water production system and a pure water production method.

Conventionally, an electric deionization apparatus (EDI) has been used in the production of pure water used for cleaning water, medical water and the like used in the production process of semiconductors and liquid crystal displays. The electric deionization device performs deionization treatment of raw water while electrically regenerating an ion exchanger in the device. Therefore, in the electric deionization apparatus, continuous water sampling is possible without requiring regeneration with a chemical unlike the ion exchange resin tower.

The electric deionization apparatus comprises a deionization chamber filled with an ion exchanger between a cation exchange membrane that allows only cations (cations) to permeate and an anion exchange membrane that allows only anions (anions) to permeate, In this configuration, a concentration chamber is arranged outside the cation exchange membrane and the anion exchange membrane. Then, an anode is disposed on the anion exchange membrane side via an electrode chamber (anode chamber) and a cathode is disposed on the cation exchange membrane side via an electrode chamber (cathode chamber) as viewed from the desalting chamber. When the water to be treated is passed through the desalination chamber with a DC voltage applied between the anode and the cathode, the ionic components in the water to be treated are captured by the ion exchanger in the desalination chamber, and the water dissociation reaction occurs. The ion exchanger is regenerated by hydrogen ions (H ⁺ ) and hydroxide ions (OH ⁻ ) generated by the ion exchanger.

よう Thus, in the electric deionization apparatus, the water to be treated is deionized and purified by passing through the deionization chamber. On the other hand, for example, water to be treated is also passed through the concentration chamber and the electrode chamber. In the water to be treated passing through the concentration chamber and the electrode chamber, the ionic components moved from the desalting chamber are concentrated and discharged as concentrated water outside the electric deionization apparatus.

As a pure water production system using this electric deionizer, deionized water is obtained by a reverse osmosis membrane device (RO), and organic components in the deionized water are decomposed by an ultraviolet oxidizer (TOC-UV). There is a system in which an ionic component such as a low molecular weight organic acid generated in an ultraviolet oxidation device is treated by an electric deionization device. As a system provided with such an electric deionization device, a system in which an electric deionization device is provided in two stages and a part of the treated water in a desalination chamber is passed through a concentration chamber (for example, see Patent Document 1). ) In order to prevent deterioration of the ion exchanger due to oxidizing components generated by the ultraviolet oxidizer, an ultraviolet sterilizer that irradiates ultraviolet light having a longer wavelength than the ultraviolet oxidizer between the ultraviolet oxidizer and the electric deionizer. There is also proposed a providing system (for example, see Patent Document 2).

In recent years, with the ultra-high integration of large-scale integrated circuits (LSIs), there has been an increasing demand for higher quality of ultrapure water for semiconductor production. In particular, there is a demand for ultrapure water in which trace impurities such as silica and boron in water are significantly reduced in concentration. However, in an attempt to improve the removal rate of trace impurities, the conventional method of providing a two-stage electrodeionization apparatus has a problem in that the water recovery rate and current efficiency in the electrodeionization apparatus decrease. In a device provided with two stages of ultraviolet lamps, there is a problem that the number of devices to be used increases, which complicates the system and increases costs. Therefore, a method capable of efficiently producing high-quality pure water for a long period of time has been required.

JP 2006-51423 A JP 2011-45824 A

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a pure water production system and a pure water production method capable of producing high-quality pure water stably for a long period of time. I do.

The pure water production system of the present invention is a pure water production system including a reverse osmosis membrane device, an ultraviolet oxidation device, an electric deionization device, and a treatment water pipe connecting these devices in order from the upstream side. The electric deionization apparatus includes a cation exchange membrane and an anion exchange membrane that are alternately arranged, a concentration chamber and a desalination chamber that are alternately formed between the cation exchange membrane and the anion exchange membrane, and the cation exchange membrane. And a pair of electrode chambers disposed outside the anion exchange membrane, wherein the treated water pipe supplies treated water treated by the ultraviolet oxidizer to at least a desalination chamber of the electric deionizer. The pure water production system is connected to the electric deionization apparatus so that the permeated water of the reverse osmosis membrane apparatus does not pass through the ultraviolet oxidizing apparatus. Characterized in that it comprises a first bypass pipe for supplying the

The pure water production system of the present invention may further include a second bypass pipe for supplying permeated water of the reverse osmosis membrane device to the concentration chamber of the electric deionization device without passing through the ultraviolet oxidizing device. preferable.

In the pure water production system of the present invention, the electric deionizer has a common inlet nozzle communicating with a concentration chamber and an electrode chamber of the electric deionizer, and the first bypass pipe and the second Preferably, all bypass pipes are connected to the common inlet nozzle.

In the pure water production system of the present invention, the electric deionizer has a concentration chamber inlet nozzle communicating with a concentration chamber of the electric deionizer and an electrode chamber inlet nozzle communicating with an electrode chamber. Is preferably connected to the electrode chamber inlet nozzle, and the second bypass pipe is preferably connected to the concentration chamber inlet nozzle.

において In the pure water production system of the present invention, it is preferable that an ion exchanger is provided in the concentration chamber and the electrode chamber.

において In the pure water production system of the present invention, the concentration of hydrogen peroxide in the treated water treated by the ultraviolet oxidizing device is preferably 100 μg / L or less.

The pure water production method of the present invention is a pure water production method in which raw water is sequentially treated with a reverse osmosis membrane device, an ultraviolet oxidizing device, and an electric deionization device, wherein the electric deionization device is alternately treated. A cation exchange membrane and an anion exchange membrane, and a concentration chamber and a desalination chamber alternately formed between the cation exchange membrane and the anion exchange membrane, and are disposed outside the cation exchange membrane and the anion exchange membrane. A pair of electrode chambers, and supplies the treated water treated by the ultraviolet oxidizing apparatus to at least a desalting chamber of the electric deionization apparatus, and the permeated water of the reverse osmosis membrane apparatus, The power is supplied to the electrode chamber of the electric deionization apparatus without passing through the ultraviolet oxidation apparatus.

In the pure water production method of the present invention, it is preferable that the permeated water of the reverse osmosis membrane device is supplied to the concentration chamber of the electric deionization device without passing through the ultraviolet oxidation device.

において In the pure water production method of the present invention, the concentration of hydrogen peroxide in the treated water treated by the ultraviolet oxidizing apparatus is preferably 100 μg / L or less.

According to the pure water production system and the pure water production method of the present invention, high-quality pure water can be produced stably for a long period of time.

1 is a block diagram schematically illustrating an example of a pure water production system according to an embodiment. FIG. 2 is a diagram schematically illustrating an example of an electric deionization device used in the pure water production system illustrated in FIG. 1. It is a figure which shows roughly another example of the electric deionization apparatus used in the pure water production system shown in FIG. It is a block diagram showing roughly another example of the pure water production system of an embodiment. It is a block diagram showing roughly another example of the pure water production system of an embodiment. It is a block diagram showing roughly the pure water production system used in the example.

Hereinafter, embodiments will be described in detail with reference to the drawings. The present invention is not limited to these embodiments, and these embodiments can be changed or modified without departing from the spirit and scope of the present invention. In the following drawings, the same components are denoted by the same reference numerals, and description of overlapping operations will be omitted.

The pure water production system 1 of the embodiment shown in FIG. 1 includes a reverse osmosis membrane device 10, an ultraviolet oxidation device (TOC-UV) 11, an electric deionization device (EDI) 12, and these devices from the upstream side. The processing water pipe 133 connected in that order is provided. The pure water production system 1 processes pure water by treating the raw water supplied from the raw water supply unit 20, and supplies the pure water to a use point (POU) 14, which is a place of use. It is.

In the pure water production system 1, the treated water pipe 133 is a first treated water pipe 133 a that supplies treated water from the treated water supply unit 20 to the reverse osmosis membrane device 10, and an ultraviolet oxidation device that transmits permeated water of the reverse osmosis membrane device 10. A second treated water pipe 133b for supplying the treated water treated by the ultraviolet oxidizing apparatus 11 to the electric deionization apparatus 12, and a second treated water pipe 133c for supplying treated water treated by the ultraviolet oxidizing apparatus 11 to the electric deionization apparatus 12. And a fourth treated water pipe 133d for sending the liquid to a use point 14 where pure water is used.

The pure water production system 1 branches from the second treated water pipe 133b that supplies the permeated water of the reverse osmosis membrane device 10 to the ultraviolet oxidizing device 11, and transfers the permeated water of the reverse osmosis membrane device 10 to the electric deionization device 12. It has a first bypass pipe 131 for supplying. A discharge pipe 135 for discharging the concentrated water is connected to the reverse osmosis membrane device 10.

As illustrated below, the electric deionization apparatus 12 includes a cation exchange membrane and an anion exchange membrane that are alternately arranged, and a concentration chamber and a deionization chamber that are alternately formed between the cation exchange membrane and the anion exchange membrane. It has a salt room. Further, the electrodeionization device 12 includes a pair of electrode chambers disposed outside the cation exchange membrane and the anion exchange membrane.

In the pure water production system 1, a third treated water pipe 133c and a first bypass pipe 131 are connected to the electric deionizer 12 as a water supply pipe. The treated water treated by the ultraviolet oxidizer 11 supplied from the ultraviolet oxidizer 11 to the electric deionizer 12 through the third treated water pipe 133c is supplied to at least the desalting chamber of the electric deionizer 12. . In the pure water production system 1, the permeated water of the reverse osmosis membrane device 10 supplied from the reverse osmosis membrane device 10 to the electric deionization device 12 via the first bypass pipe 131 is supplied to the electric deionization device 12. It is supplied to the electrode chamber. Further, a fourth treated water pipe 133d for discharging permeated water as deionized water and a concentrated water discharge pipe 136 for discharging concentrated water are connected to the electric deionization device 12 as drain pipes.

2A and 2B schematically show an example of the electric deionization device 12 used in the pure water production system 1 and another example. FIG. 2A shows an example of the electric deionization apparatus 12 in the case where the treated water treated by the ultraviolet oxidation apparatus 11 is supplied to the desalination chamber and the concentration chamber, and the permeated water of the reverse osmosis membrane apparatus 10 is supplied to the electrode chamber. Is shown. FIG. 2B shows an example of the electric deionization device 12 in the case where the treated water treated by the ultraviolet oxidation device 11 is supplied to the desalting chamber and the permeated water of the reverse osmosis membrane device 10 is supplied to the electrode chamber and the concentration chamber. Is shown. Note that, in the electric deionization device 12, the water flowing directions of the desalting chamber, the concentrating chamber, and the electrode chamber are not limited to the directions of FIGS. For example, the water flow direction of the desalting chamber and the water flow direction of the concentration chamber and the electrode chamber can be reversed.

The electric deionization device 12 shown in FIG. 2A includes a cation exchange membrane 21 and an anion exchange membrane 22 which are arranged alternately, and a concentration chamber 23 and a desalination are provided between the cation exchange membrane 21 and the anion exchange membrane 22. The chambers 24 are formed alternately. Further, outside the cation exchange membrane 21 and the anion exchange membrane 22, a pair of electrode chambers including an anode chamber 25a and a cathode chamber 25b is arranged. Further, the electric deionization apparatus 12 includes an anode 26a adjacent to the anode chamber 25a and a cathode 26b adjacent to the cathode chamber 25b, and the anode 26a and the cathode 26b (hereinafter, also referred to as “

electrodes

26a, 26b”). Is connected to a power supply 27 for applying a DC voltage.

The electric deionization device 12 shown in FIG. 2A is a water supply pipe in a concentration chamber that supplies treated water treated by the ultraviolet oxidizing apparatus 11 supplied from a third treated water pipe 133c to a concentration chamber 23 and a desalination chamber 24, respectively. 123 and a desalination chamber water supply pipe 124. Further, an electrode chamber water supply pipe 125 for supplying permeated water of the reverse osmosis membrane device 10 supplied from the first bypass pipe 131 to the anode chamber 25a and the cathode chamber 25b (hereinafter, also referred to as “

electrode chambers

25a, 25b”). Having.

電気 The electric deionization apparatus 12 shown in FIG. 2A has a deionization chamber drain pipe 224 for transferring deionized water (permeated water) deionized in the deionization chamber 24 to the fourth treated water pipe 133d. Further, it has a concentration chamber drain pipe 223 and an electrode chamber drain pipe 225 for transferring concentrated water in which ionic components discharged from the concentration chamber 23 and the

electrode chambers

25a and 25b are concentrated to the concentrated water discharge pipe 136.

The electric deionization device 12 shown in FIG. 2B has the same configuration as the electric deionization device 12 shown in FIG. 2A, except that the connection destination on the upstream side of the water supply pipe 123 for the concentration chamber is the first bypass pipe 131. .

As described above, in the pure water production system 1, after the permeated water of the reverse osmosis membrane device 10 is treated by the ultraviolet oxidation device 11, at least the desalination of the electric deionization device 12 is performed through the third treated water pipe 133c. While supplying to the chamber 24, the permeated water of the reverse osmosis membrane device 10 is supplied to at least the

electrode chambers

25 a and 25 b of the electric deionization device 12 via the first bypass pipe 131, bypassing the ultraviolet oxidation device 11. . The concentrated water 23 may be supplied with the treated water treated by the ultraviolet oxidizing device 11 or the permeated water of the reverse osmosis membrane device 10. However, it is preferable that the permeated water of the reverse osmosis membrane device 10 is supplied, for example, when the concentration chamber 23 is filled with the ion exchanger.

With the configuration described above, for example, the following effects can be obtained in the pure water production system of the embodiment as compared with the conventional pure water production system.

場合 When excessive ultraviolet irradiation is performed in the ultraviolet oxidizing apparatus, OH radicals that do not contribute to the oxidative decomposition of organic substances react with each other to generate hydrogen peroxide. The generated hydrogen peroxide may degrade the electrodes and the ion exchanger of the downstream electric deionizer. For example, in a conventional pure water production system in which treated water of an ultraviolet oxidizing apparatus is supplied to a desalting chamber, an electrode chamber, and a concentrating chamber of an electric deionization apparatus, a voltage is applied to the electric deionization apparatus. Then, the hydrogen peroxide-containing water is supplied to the electrode chamber as the treated water of the ultraviolet oxidation device. As a result, the voltage energy promotes the corrosion of the electrode by the hydrogen peroxide, and the quality of the permeated water of the electric deionization device discharged from the desalting chamber is easily reduced.

In addition, when the ion exchanger is filled in the concentration chamber, the deterioration of the ion exchanger is promoted, and the quality of the permeated water of the electric deionization apparatus is easily reduced. In order to improve the removal rate of trace impurities such as silica and boron, a voltage near the allowable upper limit may be applied to the electric deionization apparatus. It is considered that the quality of the permeated water decreases more easily due to the progress of body corrosion.

On the other hand, in the pure water production system 1 of the embodiment, the

electrode chambers

25a, 25b, or, while supplying the treated water treated by the ultraviolet oxidizing apparatus 11 to at least the desalting chamber 24 of the electric deionization apparatus 12, The permeated water of the reverse osmosis membrane device 10 that has not passed through the ultraviolet oxidation device 11 is introduced into the

electrode chambers

25a and 25b and the concentration chamber 23. According to this, for example, a conventional pure water production system in which the permeated water of the reverse osmosis membrane device 10 is supplied to a desalting chamber, an electrode room, and a concentration room of an electric deionization device via an ultraviolet oxidation device. By simply changing the pipes and their connection points in the above, the adverse effect on the electric deionization apparatus due to hydrogen peroxide generated in the ultraviolet oxidation apparatus can be suppressed without increasing the number of processing apparatuses.

In addition, in the conventional method, in order to prevent the above-mentioned corrosion of the electrodes and the ion exchanger from progressing, water may be supplied to the electric deionization apparatus from the secondary pure water system disposed immediately before the point of use. However, in the pure water production system 1 of the embodiment, such a necessity is not required. Further, in the pure water production system 1, the permeated water of the reverse osmosis membrane device 10 is supplied to the

electrode chambers

25 a and 25 b of the electric deionization device 12, or both the

electrode chambers

25 a and 25 b and the concentration chamber 23. Hardness scale hardly occurs in the

chambers

25a and 25b or the

electrode chambers

25a and 25b and the concentration chamber 23, and the deterioration of the quality of boron or silica in the treated water of the electric deionization apparatus 12 is reduced.

The pure water production system according to the embodiment may include, if necessary, other water treatment devices other than these, in addition to the reverse osmosis membrane device, the ultraviolet oxidation device, and the electric deionization device. Examples of such other water treatment devices include, for example, a degassing membrane device, a vacuum degassing device, an ion exchange resin tower, a hardness removing device (softener), an activated carbon packed tower, a coagulating sedimentation tank, and a filtering device. Pneumatic membrane devices are preferably used. If the pure water production system of the embodiment has another water treatment device, the arrangement location may be before the reverse osmosis membrane device, even between the above-mentioned essential water treatment devices, and may be an electric deionization device. It may be at the subsequent stage of the device.

純 The pure water production system 1A of the embodiment shown in FIG. 3 is an example in which a degassing membrane device is provided downstream of the electric deionization device as another water treatment device. The pure water production system 1A shown in FIG. 3 includes a reverse osmosis membrane device 10, an ultraviolet oxidation device 11, an electric deionization device 12A, a degassing membrane device (MGD) 13, and these devices in that order from the upstream side. The processing water pipe 133 to be connected is provided. Specifically, the reverse osmosis membrane device 10, the ultraviolet oxidation device 11, the electric deionization device 12A and the degassing membrane device 13 are connected by the second treated water pipe 133b to the fourth treated water pipe 133d. To-be-treated water is supplied to the reverse osmosis membrane device 10 via the first treated water pipe 133a. The permeated water of the degassing membrane device 13 is sent to a use point (POU) 14 which is a place where pure water is used by a fifth treated water pipe 133e.

The pure water production system 1A includes a first bypass pipe 131 and a second bypass pipe 132 which branch off from the second treated water pipe 133b and extend to the electric deionization apparatus 12A.

The electric deionization apparatus 12A can be, for example, an electric deionization apparatus having the same configuration as that shown in FIG. 2B except for the connection destination of the water supply pipe 123 in the concentration chamber. The electric deionization apparatus 12A includes a concentration chamber inlet nozzle 23c communicating with the concentration chamber 23 inside the electric deionization apparatus, a desalination chamber inlet nozzle 24c communicating with the desalination chamber 24, and an electrode chamber communicating with the

electrode chambers

25a and 25b. An inlet nozzle 25c.

In the pure water production system 1A shown in FIG. 3, the third treated water pipe 133c is connected to the deionization chamber inlet nozzle 24c of the electric deionization device 12A, and the reverse osmosis membrane device 10 and the ultraviolet oxidation device 11 The water treated in this order is supplied to the desalting chamber 24 of the electric deionizer 12A.

第 The first bypass pipe 131 branched from the second treated water pipe 133b is connected to the electrode chamber inlet nozzle 25c of the electric deionization apparatus 12A. In addition, a second bypass pipe 132 branched from the second treated water pipe 133b is connected to the enrichment chamber inlet nozzle 23c of the electric deionization apparatus 12A. The first bypass pipe 131 supplies the permeated water of the reverse osmosis membrane device 10 to the

electrode chambers

25a and 25b of the electric deionization device 12A without passing through the ultraviolet oxidation device 11. The second bypass pipe 132 supplies the permeated water of the reverse osmosis membrane device 10 to the concentration chamber 23 of the electric deionization device 12A without passing through the ultraviolet oxidation device 11.

In the pure water production system 1A shown in FIG. 3, instead of branching the second bypass pipe 132 from the second treated water pipe 133b, it is also possible to branch the second bypass pipe 132 from the third treated water pipe 133c. In that case, the treated water treated by the ultraviolet oxidizing device 11 is supplied to the concentration chamber 23 of the electric deionization device 12A.

した In the pure water production system 1A shown in FIG. 3, an example has been described in which the electric deionization apparatus 12A having the electrode chamber inlet nozzle 25c and the concentration chamber inlet nozzle 23c independently of each other is used. In the pure water production system of the embodiment, for example, an electric deionization apparatus having a common inlet nozzle that also serves as an electrode chamber inlet nozzle and a concentration chamber inlet nozzle may be used.

純 The pure water production system 1B shown in FIG. 4 is a pure water production system having the same configuration as the pure water production system 1A shown in FIG. 3, except that the electric deionization device 12A is replaced with an electric deionization device 12B. The electric deionization apparatus 12B has the same configuration as the electric deionization apparatus 12A except that the electrode chamber inlet nozzle 25c and the concentration chamber inlet nozzle 23c are replaced with a common inlet nozzle 31c serving also as these two nozzles. In the pure water production system 1B, both the first bypass pipe 131 and the second bypass pipe 132 are connected to the common inlet nozzle 31c of the electric deionization apparatus 12B.

In the electric deionizer 12B, the treated water treated by the ultraviolet oxidizer 11 is supplied to the desalting chamber 24, and the permeated water of the reverse osmosis membrane apparatus 10 is supplied to the

electrode chambers

25a and 25b and the concentration chamber 23.

In the pure water production system 1B shown in FIG. 4, the first bypass pipe 131 may have the function of the second bypass pipe without providing the second bypass pipe 132.

Next, a pure water production method according to the embodiment will be described using a pure water production method using the pure water production system 1A shown in FIG. 3 as an example. In addition, a reverse osmosis membrane device, an ultraviolet oxidation device, and an electric deionization device used in the pure water production system of the embodiment will be described in detail.

被 The water to be treated in the pure water production system 1A is, for example, raw water or raw water pretreated by a pretreatment unit. Raw water is pre-processed by a pre-processing unit as necessary, and supplied to the reverse osmosis membrane device 10. As raw water, municipal water, well water, groundwater, industrial water, semiconductor manufacturing plants, and the like, water that is collected and pretreated (recovered water) is used. The pretreatment unit removes suspended substances in raw water to generate pretreatment water. The pretreatment unit is configured by appropriately selecting a sand filtration device, a microfiltration device, and the like for removing suspended substances in raw water, and further, a heat exchanger for adjusting the temperature of the pretreatment water as necessary. It is comprised including. Note that the pretreatment unit may be omitted depending on the quality of the raw water.

In the reverse osmosis membrane device 10, the water to be treated is subjected to reverse osmosis membrane filtration to remove salts, ionic organic substances, colloidal organic substances, and the like in the water to be treated. Examples of the reverse osmosis membrane included in the reverse osmosis membrane device 10 include a cellulose triacetate-based asymmetric membrane and a polyamide-based, polyvinyl alcohol-based, or polysulfone-based composite membrane. The membrane shape is a sheet flat membrane, a spiral membrane, a tubular membrane, a hollow fiber membrane, or the like, but is not limited thereto. Above all, a polyamide-based composite film is preferable in terms of high rejection, and a cross-linked wholly aromatic polyamide-based composite film is more preferable. The shape of the film is preferably a spiral film.

脱 The desalination rate of the reverse osmosis membrane device 10 is preferably 96 to 99.8%. The desalination rate is 25 ° C., pH = 7, water supply rate of NaCl concentration 0.2% by mass is water recovery rate 15%, and feed water pressure is standard pressure (for example, 1.5 MPa for a low pressure reverse osmosis membrane device, ultra low pressure reverse osmosis). In the case of a membrane device, it can be measured as the removal rate of sodium ions when water is passed through the reverse osmosis membrane at 0.75 MPa). The water recovery of the reverse osmosis membrane device 10 is preferably from 60 to 98%, more preferably from 80 to 95%, from the viewpoint of efficiently removing salts and ionic organic substances.

The reverse osmosis membrane device 10 may be any of an ultra-low pressure type, a low pressure type, and a high pressure type reverse osmosis membrane device, and from the viewpoint of the production efficiency of ultrapure water, an ultra low pressure type or a low pressure type reverse osmosis membrane device. It is preferred that Further, it is preferable that a water supply pump is provided upstream of the reverse osmosis membrane device 10 to pressurize the water to be treated to a predetermined pressure and supply the water to the reverse osmosis membrane device 10. Further, a scale inhibitor, a bacteriostat, a pH adjuster, and the like may be added to the water supply of the reverse osmosis membrane device 10 as necessary.

Here, the operating pressure of the ultra-low pressure reverse osmosis membrane is 0.4 MPa to 0.8 MPa, preferably 0.6 MPa to 0.7 MPa. The low pressure type reverse osmosis membrane has an operating pressure of more than 0.8 MPa and less than 2.5 MPa, preferably 1 MPa to 1.6 MPa. The high pressure type reverse osmosis membrane has an operating pressure of more than 2 MPa and 8 MPa or less, preferably more than 5 MPa and 6 MPa or less. The ultra-low pressure type, low pressure type and high pressure type are distinguished by the design pressure (standard pressure) at the time of production of each reverse osmosis membrane. There is also.

The reverse osmosis membrane device 10 may be constituted by a two-stage reverse osmosis membrane device in which two reverse osmosis membrane devices are connected in series. In this case, in terms of efficiently removing salts and ionic organic substances, the water recovery rate is preferably 60 to 98%, more preferably 80 to 95% in the first-stage reverse osmosis membrane device. In the reverse osmosis membrane device of the second stage, it is preferably 80 to 95%, more preferably 85 to 95%.

Commercial products of the reverse osmosis membrane device 10 include TM820K-400, TM720-400, TM720D-400 and SUL-G20 manufactured by Toray Industries, BW30-400 and BW30-400FR manufactured by DOW, CPA5 manufactured by Nitto Denko Corporation, CPA5-LD or the like can be used.

Next, the permeated water of the reverse osmosis membrane device 10 is introduced into the ultraviolet oxidation device 11. The ultraviolet oxidizer 11 irradiates the permeated water of the reverse osmosis membrane device 10 with ultraviolet rays to decompose and remove organic substances (TOC) in the water. The ultraviolet oxidation device 11 is, for example, a device having an ultraviolet lamp and generating ultraviolet light having a wavelength of about 185 nm. The ultraviolet oxidizing device 11 may further generate ultraviolet light having a wavelength of about 254 nm. When water is irradiated with ultraviolet light in the ultraviolet oxidation device 11, the ultraviolet light decomposes water to generate OH radicals, and the OH radicals oxidize and decompose organic substances in the water.

When excessive ultraviolet irradiation is performed in the ultraviolet oxidizer 11, OH radicals that do not contribute to the oxidative decomposition of organic substances react with each other to generate hydrogen peroxide. The generated hydrogen peroxide may deteriorate the

electrodes

26a and 26b and the ion exchanger of the downstream electric deionizer 12A. In order to reduce the hydrogen peroxide flowing out of the ultraviolet oxidizer 11 and to suppress the deterioration of the

electrodes

26a and 26b and the ion exchanger of the downstream electric deionizer 12A, the amount of ultraviolet irradiation in the ultraviolet oxidizer 11 is , 0.02 to 0.5 kWh / m ³ . The concentration of hydrogen peroxide in the treated water treated by the ultraviolet oxidizer 11 is preferably 100 μg / L or less, more preferably about 10 μg / L to about 40 μg / L.

処理 The treated water of the ultraviolet oxidizing apparatus 11 is supplied into the desalting chamber 24 from the desalting chamber inlet nozzle 24c of the electric deionization apparatus 12A via the third treated water pipe 133c. The permeated water of the reverse osmosis membrane device 10 is supplied to the concentration chamber 23 and the

electrode chambers

25a and 25b of the electric deionization apparatus 12A via the second bypass pipe 132 and the first bypass pipe 131, respectively.

Note that, in the pure water production system 1A shown in FIG. 3 using the electric deionization device 12A, the second bypass pipe 132 is branched from the third treated water pipe 133c instead of the second treated water pipe 133b. Then, the treated water of the ultraviolet oxidizing apparatus 11 may be supplied to the desalting chamber 24 and the concentrating chamber 23 of the electric deionization apparatus 12A, and the permeated water of the reverse osmosis membrane apparatus 10 may be supplied to the

electrode chambers

25a and 25b. As described above, in the pure water production method of the embodiment, the treated water of the ultraviolet oxidizer is supplied to at least the desalting chamber of the electric deionizer, and the permeated water of the reverse osmosis membrane device is supplied to at least the electric deionizer. It is supplied to the electrode chamber.

構成 The configuration of the electric deionizer 12A is as described above. In the electric deionizer 12A, the desalting chamber 24 is filled with an ion exchanger. The interior of the concentration chamber 23 and the

electrode chambers

25a and 25b may be hollow, or may be filled with an electrical conductor made of an ion exchanger, activated carbon, metal, or the like.

At this time, the amount of water supplied to the desalination chamber 24 of the electric deionization apparatus 12A and the total amount of water supplied to the concentration chamber 23 and the

electrode chambers

25a and 25b of the electric deionization apparatus 12A Is a value expressed as (water supplied into the desalting chamber 24) / (total water supplied into the concentrating chamber 23 and the

electrode chambers

25a and 25b) and is 6 to 20. Is preferred. Thereby, the effect of suppressing the deterioration of the electric deionization device 12A and the effect of improving the treated water quality can be easily improved.

In the electric deionization apparatus 12A, the ion exchange membrane arranged on the anode 26a side in contact with the desalting chamber 24 is the anion exchange membrane 22, and the ion exchange membrane arranged on the cathode 26b side in contact with the desalination chamber 24. Is a cation exchange membrane 21. Further, the electric deionization apparatus 12A may be configured such that a plurality of cells are juxtaposed by alternately having a plurality of desalting chambers 24 and a concentration chamber 23 between the anode 26a and the cathode 26b. .

As the cation exchange membrane 21 and the anion exchange membrane 22, there are a heterogeneous membrane, a semi-homogeneous membrane, and a homogeneous membrane in view of the membrane structure. This is preferable in terms of suppressing an increase in resistance in the ion device.

は As the ion exchanger filled in the desalting chamber 24, an ion exchanger obtained by mixing a cation exchange resin and an anion exchange resin can be used. The mixing ratio of the cation exchange resin and the anion exchange resin is, in terms of volume ratio, that the anion exchange resin ratio is from 20 to 80% in view of the efficiency of removing the ionic components and the increase in the resistance in the electric deionizer 12A. It is preferable in terms of suppression. As the ion exchanger, it is also possible to use an ion exchanger obtained by laminating a cation exchange resin and an anion exchange resin in the flow direction. For the electrodes (anode 26a and cathode 26b), for example, the anode is made of a platinum group element or a metal material coated with a platinum group element, and the cathode is made of stainless steel.

In the electric deionizer 12A, it is preferable that the concentration chamber 23 or the

electrode chambers

25a and 25b be filled with an ion exchange resin as an ion exchanger. In the case where the ion exchange resin is filled in the concentration chamber 23 or the

electrode chambers

25a and 25b, the use of the method of the present invention suppresses the deterioration of the ion exchange resin in the concentration chamber 23 or the

electrode chambers

25a and 25b. Deterioration of the deionizer 12A is suppressed, and high-quality treated water can be continuously obtained. If the ion exchange resin is filled in either the concentration chamber 23 or the

electrode chambers

25a and 25b, the effect of the present invention is remarkably obtained, and the ion exchange resin is filled in both the concentration chamber 23 and the

electrode chambers

25a and 25b. If so, the effect of the present invention can be more remarkably obtained.

When the permeated water of the reverse osmosis membrane device 10 is supplied only to the

electrode chambers

25a and 25b as in the electric deionization device 12 shown in FIG. 2A, the ion exchange resin is filled in the

electrode chambers

25a and 25b. In this case, the effect of the present invention is remarkable.

In the electric deionizer 12A, the water to be treated is supplied from one end of the desalting chamber 24 and flows out from the other end of the desalting chamber 24. In this process, ion components in the water to be treated are adsorbed by the ion exchanger in the desalting chamber 24. At this time, a rectified DC current is supplied between the anode 26a and the cathode 26b. The current flows in a direction orthogonal to the flow of the water to be treated in the desalting chamber 24. The current dissociates water into hydrogen ions and hydroxide ions, and the dissociated hydrogen ions and hydroxide ions exchange with the ion components adsorbed on the ion exchanger, respectively. The exchanged ion components move to the concentration chamber 23, the anode chamber 25a, and the cathode chamber 25b, and are discharged from the electric deionization apparatus 12A via the concentrated water discharge pipe 136 via these.

The water recovery in the electric deionizer 12A is preferably 90 to 96%, and the current density in the electric deionizer 12A is preferably 300 to 3000 mA / dm ² , and 1500 to 2500 mA / dm ^2. Is more preferred. When the current density is 300 mA / dm ² or more, electrode corrosion due to hydrogen peroxide is likely to occur normally. However, in the pure water production system of the embodiment, at least in the electrode chamber of the electric deionization apparatus, preferably in the electrode chamber and the concentration chamber. This is because water that has not passed through the ultraviolet oxidizing device is supplied, and this can be suppressed. In addition, by setting the current density in a more preferable range, the removal rate of a weak electrolyte such as boron can be stabilized for a long time.

市販 A commercially available electric deionizer can be used as the electric deionizer 12A. As commercial products of the electric deionization apparatus 12A, for example, VNX50, VNX55, VNX-55EX (all manufactured by Evoqua), EDI-50 (manufactured by IONICS) and the like can be used.

The power supply 27 is, for example, an AC-DC converter that converts an alternating current (AC) current supplied from an alternating current power supply into a direct current (DC) current. The power supply 27 is preferably a switching type AC-DC converter or a full-wave rectification type AC-DC converter because the voltage ripple is small and high-quality treated water can be easily obtained at an early stage.

The water quality of the permeated water that has passed through the electric deionization apparatus 12A has a boron concentration of, for example, 1 μg / L (as B, the same applies hereinafter) and a specific resistance of 17.5 MΩ · cm or more even when one unit is used in a single stage. Can be obtained. As the electric deionization apparatus 12A, one unit may be used in a single stage, or two or more units may be connected in series and used as a plurality of stages. The permeated water that has passed through the electric deionization device 12A is then supplied to the degassing membrane device 13.

(4) The degassing film device 13 mainly removes carbon dioxide gas generated by decomposing organic components in the ultraviolet oxidation device 11. The degassing membrane device 13 dissolves the dissolved gas in the water to be treated by passing the water to be treated through the primary side of the gas-permeable membrane (degassing membrane) while reducing the pressure on the secondary side of the membrane as necessary. This is an apparatus that removes only by transferring to the secondary side. An inert gas source such as nitrogen may be connected to the decompression side (secondary side) of this film to improve the degassing performance. The degassing film may be a film that allows gas such as oxygen, nitrogen, and vapor to pass through but does not allow water to permeate, and examples thereof include a silicon rubber-based, polytetrafluoroethylene-based, polyolefin-based, and polyurethane-based film.

According to the pure water production system of the embodiment described above, deterioration of the electrodes and the ion exchanger in the electric deionization device can be suppressed, so that high-quality pure water can be obtained for a long period of time. Further, since the permeated water of the reverse osmosis membrane device is introduced into at least the electrode chamber, preferably into the electrode chamber and the concentration chamber, silica scale can be suppressed, and the removal rate of trace impurities such as silica and boron can be improved or removed. The effect of suppressing the rate reduction is also easily obtained.

Next, examples will be described. The present invention is not limited to the following examples.

(Example 1 and Comparative Example 1)
FIG. 5 is a diagram illustrating a configuration of the pure water production system 50 used in Example 1 and Comparative Example 1. In the pure water production system 50, the electric deionization device 53 is used in Example 1, and the electric deionization device 54 is used in Comparative Example 1. Otherwise, the apparatus included in the pure water production system 50 is commonly used in Example 1 and Comparative Example 1.

The pure water production system 50 includes a reverse osmosis membrane device 51 (Toray Industries, Inc., TM820K-400) and an ultraviolet oxidizing device 52 (Nihon Photo Science Co., Ltd., AUV-8000TOC, ultraviolet irradiation amount 0.3 kWh / m ³ ). An electric deionizer 53, 54 (EVOQUA, VNX-55EX, treated water amount 10 m ³ / h, in which the ion exchange resin is filled in the concentration chamber and the electrode chamber, is provided downstream of the ultraviolet oxidizer 52. (95% water recovery).

The pure water production system 50 includes a makeup water line 55a for supplying the water to be treated to the reverse osmosis membrane device 51, a makeup water line 55b for connecting the reverse osmosis membrane device 51 and the ultraviolet oxidizer 52, an ultraviolet oxidizer 52 and an electric type. A replenishment water line 55c connecting the inlets of the deionization chambers of the

deionizers

53 and 54 and a treated water line 55d for discharging the permeated water of the electric deionizers 53 and 54 are provided. In the above, the permeated water of the reverse osmosis membrane device 51 flows through the makeup water line 55b. The concentrated water of the reverse osmosis membrane device 51 is discharged through a drain pipe 57. The concentrated water of the electric deionizers 53 and 54 is discharged through a drain pipe 56.

Further, the permeated water of the reverse osmosis membrane device 51 is supplied to the electrode chamber and the concentration chamber inlet of the electric deionization device without passing through the ultraviolet oxidizing device 52 to the electric deionization device 53 used in Example 1. The bypass makeup water line 53a is connected. Further, a replenishing water line 54a for supplying the treated water of the ultraviolet oxidizing device 52 to the electrode chamber and the concentration chamber is connected to the electric deionization device 54 used in Comparative Example 1.

In Example 1 and Comparative Example 1, treated water from which tap water was passed through activated carbon to remove chlorine was supplied to the pure water production system 50 from the makeup water line 55a, and continuous operation was performed for 24 hours. Pure water was produced. At this time, in the

electric deionization devices

53 and 54, a direct current was applied in a constant voltage mode of 180 V in order to easily evaluate a decrease in performance due to deterioration of the electric deionization device. The current density was 1810 mA / dm ² at the beginning of water flow.

Immediately after the start of operation (initial flow of water) and 300 days after the start of operation, at each point (permeate outlet of the reverse osmosis membrane device 51 (near the connection point of the make-up water line 55b with the reverse osmosis membrane device 51), The treated water outlet of the ultraviolet oxidizer 52 (near the connection point of the makeup water line 55c with the ultraviolet oxidizer 52), the permeated water outlet of the electric deionizers 53 and 54 (the electric deionizer 53 of each treated water line 55d) , 54)) (water conductivity (conductivity [μS / cm])). Table 1 shows the results.

From Table 1, in the pure water production system of Example 1, the conductivity of the treated water discharged from the permeated water outlet of the electric deionization device 53 was not changed from the initial value of the water flow after 300 days from the start of operation. Further, it can be seen that the quality of the treated water is improved even when compared with the conductivity of the treated water discharged from the permeated water outlet of the electric deionization device 54 in the pure water production system of Comparative Example 1.

(Example 2 and Comparative Example 2)
In the system of FIG. 5, the electric deionizers 53 and 54 in which the ion exchange resin is not filled in the concentration chamber and the electrode chamber (IONICS, EDI-50, treated water amount 10 m ³ / h, concentrated water circulating water amount 15 m ³ / h , Water recovery 95%), and the same test as in Example 1 and Comparative Example 1. EDI-50 usually requires circulation of concentrated water and injection of sodium chloride into the concentrated water, and was also performed in Example 2 and Comparative Example 2, but is omitted in the drawings. At this time, in the electric deionizers 53 and 54, a direct current was applied in a constant voltage mode of 580V. The current density was 314 mA / dm ² at the beginning of water flow. Table 2 shows the results.

From Table 2, the method of supplying the permeated water of the osmosis membrane apparatus to the concentration chamber and the electrode chamber of the electric deionization apparatus without passing through the ultraviolet oxidation apparatus is different from that of the pure water production system of Example 2 in that the concentration chamber and It can be seen that the effect is also obtained when an electric deionization apparatus in which the electrode chamber is not filled with the ion exchange resin is used. However, the difference in the quality of the treated water after 300 days between the pure water production system of Example 2 and the pure water production system of Comparative Example 2 is due to the fact that the ion concentration in the concentrating chamber and the electrode chamber was different as in Example 1 and Comparative Example 1. It is smaller than the difference in the quality of the treated water when an electric deionization apparatus filled with exchange resin is used. This is presumably because the concentration chamber and the electrode chamber are not filled with the ion exchange resin, and there are few locations affected by hydrogen peroxide.

As described above, in the pure water production systems of Examples 1 and 2 in which the permeated water of the reverse osmosis membrane device 51 is used as makeup water to the electrode chamber inlet of the electric deionization device 53, the outlet of the ultraviolet oxidizer 52 is used. Compared to the pure water production systems of Comparative Examples 1 and 2, in which water is used as makeup water at the inlet of the desalting chamber and the inlet of the electrode chamber of the electric deionization device 54, it is possible to supply treated water having a low conductivity for a long time. confirmed.

As described above in detail, according to the pure water production system of the present invention, reverse water not containing hydrogen peroxide which is a by-product of the ultraviolet oxidizer is used as makeup water to the electrode chamber inlet of the electric deionizer. By using the permeated water of the permeable membrane device, high-purity treated water can be provided for a long period of time without corrosion of the electrode.

1, 1A, 1B ... pure water production system, 10 ... reverse osmosis membrane device, 11 ... ultraviolet oxidation device (TOC-UV), 12, 12A, 12B ... electric deionization device (EDI), 13 ... degassing membrane device (MDG), 14 ... Point of use (POU), 23c ... Enrichment chamber inlet nozzle, 24c ... Demineralization chamber inlet nozzle, 25c ... Electrode chamber inlet nozzle, 31c ... Common inlet nozzle, 131 ... First bypass pipe, 132 ... 2nd bypass pipe, 133 ... treated water pipe, 21 ... cation exchange membrane, 22 ... anion exchange membrane, 23 ... concentration chamber, 24 ... desalination chamber, 25a ... anode chamber, 25b ... cathode chamber, 26a ... anode, 26b ... Cathode, 27 power supply.

Claims

A reverse osmosis membrane device, an ultraviolet oxidation device, an electric deionization device, and a pure water production system including a treatment water pipe connecting these devices in that order from the upstream side,
The electrodeion deionizer, a cation exchange membrane and an anion exchange membrane that are alternately arranged,
A concentration chamber and a desalination chamber alternately formed between the cation exchange membrane and the anion exchange membrane,
A pair of electrode chambers disposed outside the cation exchange membrane and the anion exchange membrane,
The treated water pipe is connected to the electric deionizer so as to supply treated water treated by the ultraviolet oxidizer to at least a desalination chamber of the electric deionizer,
The pure water production system includes a first bypass pipe that supplies permeated water of the reverse osmosis membrane device to an electrode chamber of the electric deionization device without passing through the ultraviolet oxidizing device. Water production system.
The method according to claim 1, further comprising a second bypass pipe configured to supply permeated water of the reverse osmosis membrane device to a concentration chamber of the electric deionization device without passing through the ultraviolet oxidation device. Pure water production system.
The electric deionizer has a common inlet nozzle communicating with the concentration chamber and the electrode chamber of the electric deionizer,
The pure water production system according to claim 2, wherein both the first bypass pipe and the second bypass pipe are connected to the common inlet nozzle.
The electric deionization device, the electric deionization device, has an enrichment chamber inlet nozzle and an electrode chamber entrance nozzle that communicates with the electrode chamber, leading to the concentration chamber,
The first bypass pipe is connected to the electrode chamber inlet nozzle,
The pure water production system according to claim 2, wherein the second bypass pipe is connected to the concentration chamber inlet nozzle.
The pure water production system according to any one of claims 1 to 4, wherein an ion exchanger is provided in the electrode chamber and the concentration chamber.
6. The pure water production system according to claim 1, wherein the concentration of hydrogen peroxide in the treated water treated by the ultraviolet oxidation device is 100 μg / L or less. 7.
Raw water, a reverse osmosis membrane device, an ultraviolet oxidation device, and a pure water production method of sequentially treating with an electric deionization device,
The electrodeion deionizer, a cation exchange membrane and an anion exchange membrane that are alternately arranged,
A concentration chamber and a desalination chamber alternately formed between the cation exchange membrane and the anion exchange membrane,
A pair of electrode chambers disposed outside the cation exchange membrane and the anion exchange membrane,
The treated water treated by the ultraviolet oxidation device is supplied to at least a desalination chamber of the electric deionization device,
A method for producing pure water, wherein the permeated water of the reverse osmosis membrane device is supplied to an electrode chamber of the electric deionization device without passing through the ultraviolet oxidation device.
The pure water production method according to claim 7, wherein the permeated water of the reverse osmosis membrane device is supplied to a concentration chamber of the electric deionization device without passing through the ultraviolet oxidizing device.
The pure water production method according to claim 7 or 8, wherein the concentration of hydrogen peroxide in the treated water treated by the ultraviolet oxidation apparatus is 100 µg / L or less.