Water treatment method and water treatment device

Abstract

A water treatment device for removing dissolved oxygen from water to be treated includes an anode (11), a cathode (12), and a dissolved oxygen removal chamber (23) disposed between the anode (11) and the cathode (12) and filled with ion exchange bodies. At least a portion of the ion exchange bodies filled in the dissolved oxygen removal chamber (23) are ion exchange bodies on which a metal catalyst is supported, such as a palladium-supported anion exchange resin (Pd AER), and the ion exchange bodies on which the metal catalyst is supported are filled in at least a portion of the dissolved oxygen removal chamber (23) in a single bed manner. Water to be treated containing hydrogen is supplied to the dissolved oxygen removal chamber (23) through a cathode chamber (25) provided with the cathode (12) while a direct current is applied between the anode and the cathode.

Description

Technical Field

[0001] This invention relates to a water treatment apparatus and a water treatment method capable of removing dissolved oxygen and other substances from water. Background Technology

[0002] As a method for removing dissolved oxygen from treated water to produce pure water, membrane degassing using a degassing membrane is known. However, in membrane degassing, a vacuum needs to be maintained on the gas phase side, which is opposite to the treated water side via the degassing membrane, thus requiring a vacuum pump. Therefore, a method for removing dissolved oxygen by adding a reducing agent such as hydrogen or hydrazine to the treated water and then contacting it with a deoxygenation catalyst supported on palladium has been put into practical use. Patent Document 1 discloses an example of removing dissolved oxygen by contacting it with a deoxygenation catalyst in the presence of hydrogen. Patent Document 2 discloses an electrolytic cell using a cathode chamber and an anode chamber divided by a solid polymer electrode membrane, where water is supplied to the cathode chamber while water electrolysis is performed, dissolved oxygen is reduced and removed in the cathode chamber by a cathode reaction, and any remaining dissolved oxygen is contacted with a deoxygenation catalyst along with hydrogen generated by electrolysis to remove dissolved oxygen.

[0003] In addition, as one of the devices for generating desalinated water from treated water, there is an electrodeionization (EDI) device. An EDI device is a combination of electrophoresis and electrodialysis, and at least its desalination chamber is filled with ion exchange resin. EDI devices have the advantage of not requiring the regeneration of ion exchange resins with chemicals. Patent Document 3 discloses that anion exchange resin and cation exchange resin are mixed and filled in the desalination chamber of the EDI device, and a portion of the anion exchange resin is a catalyst resin supported on copper and palladium. Hydrogen is added to the treated water supplied to the desalination chamber, desalination of the treated water is performed in the desalination chamber, and dissolved oxygen is removed from the treated water. Since the cathode water discharged from the cathode chamber of the EDI device contains hydrogen, Patent Document 3 also discloses using cathode water as a hydrogen source and adding the cathode water to the treated water. However, even when cathode water is added to the water being treated, since the pressure at the outlet of the cathode chamber is usually lower than the pressure of the water being treated at the inlet of the desalination chamber, a pump is needed to pressurize the cathode water in order to add it to the water being treated. Patent Document 4 discloses a method that can decompose and remove hydrogen peroxide from the water being treated by contacting it with anion exchange resin loaded with platinum, palladium, etc.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 5-96283

[0007] Patent Document 2: Japanese Patent Application Publication No. 7-241569

[0008] Patent Document 3: Japanese Patent Application Publication No. 10-272474

[0009] Patent Document 4: Japanese Patent Application Publication No. 2007-185587 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] According to the research of the inventors, there is room for improvement in the removal rate of dissolved oxygen in the treated water in the technology disclosed in Patent Document 3. Furthermore, while the technology disclosed in Patent Document 3 allows for the removal of dissolved oxygen in the treated water while simultaneously performing desalination without the need for a vacuum pump, it also requires a mechanism for adding hydrogen to the treated water. Even when cathode water is added to the treated water, a pump is needed to pressurize the cathode water because the pressure at the outlet of the cathode chamber is usually lower than the pressure at the inlet of the desalination chamber.

[0012] The purpose of this invention is to provide a water treatment method and apparatus that can efficiently remove dissolved oxygen and other substances from water with a simple structure.

[0013] Technical solutions for solving the problem

[0014] In the EDI device disclosed in Patent Document 3, a portion of the anion exchange resin filled in the desalination chamber is a catalyst resin supported on copper or palladium, and the catalyst resin is mixed with a cation exchange resin that is not a catalyst resin, i.e., the desalination chamber is filled in a mixed bed manner. However, according to the research of the present inventors, as shown in the examples and comparative examples described later, compared with the case where the catalyst resin is filled in the desalination chamber in a mixed bed manner, the dissolved oxygen removal rate is improved and the power consumption is reduced when at least a portion of the desalination chamber is filled with catalyst resin in a single bed manner. Furthermore, the present inventors, focusing on the cathode chamber, which has not been effectively utilized for desalination treatment in conventional EDI devices, have also discovered that dissolved oxygen in the treated water can be removed by causing hydrogen generated in the cathode reaction in the cathode chamber to react with dissolved oxygen in the cathode chamber. In this case, since the purpose is to remove dissolved oxygen, it is not necessarily necessary to provide a desalination chamber as an EDI device.

[0015] According to a first aspect of the present invention, a water treatment method is a method for at least removing dissolved oxygen from water to be treated, comprising: a step of applying a direct current between an anode and a cathode; and a step of introducing the water to be treated into a dissolved oxygen removal chamber disposed between the anode and cathode and filled with ion exchangers, wherein at least a portion of the ion exchangers filling the dissolved oxygen removal chamber are ion exchangers supported on a metal catalyst, and the ion exchangers supported on the metal catalyst are filled in a single bed manner in at least a portion of the dissolved oxygen removal chamber. In this water treatment method, the step of applying a direct current between the anode and the cathode and the step of introducing the water to be treated into the dissolved oxygen removal chamber can be performed simultaneously or separately.

[0016] In addition, the water treatment apparatus implementing the above method is a water treatment apparatus that at least removes dissolved oxygen contained in the water to be treated, having: an anode and a cathode; and a dissolved oxygen removal chamber disposed between the anode and the cathode and filled with ion exchangers, through which the water to be treated is introduced, wherein at least a portion of the ion exchangers filling the dissolved oxygen removal chamber are ion exchangers supported on a metal catalyst, and the ion exchangers supported on the metal catalyst are filled in a single bed manner in at least a portion of the dissolved oxygen removal chamber, and a direct current is applied between the anode and the cathode.

[0017] In the first approach, dissolved oxygen can be removed in the dissolved oxygen removal chamber because dissolved oxygen reacts with hydrogen to form water in the presence of a metal catalyst. Therefore, unless the water being treated originally contains hydrogen, hydrogen needs to be generated in the dissolved oxygen removal chamber, or hydrogen needs to be added to the water being treated upstream of the dissolved oxygen removal chamber. The water treatment apparatus according to the first approach is essentially the same as a conventional EDI apparatus, except that it is configured to remove dissolved oxygen. In the cathode chamber of the EDI apparatus, hydrogen is generated through a cathode reaction on the cathode surface. Therefore, in the water treatment apparatus of the first approach, the water to be treated is first supplied to the cathode chamber, and the outlet water of the cathode chamber, i.e., the water being treated that has passed through the cathode chamber, is passed into the dissolved oxygen removal chamber, thereby enabling the supply of hydrogen-containing water to the dissolved oxygen removal chamber. Alternatively, the cathode chamber itself can be used as the dissolved oxygen removal chamber.

[0018] In the EDI device disclosed in Patent Document 3, although outlet water from the cathode chamber is added to the treated water supplied to the desalination chamber, which functions as a dissolved oxygen removal chamber, the pressure of the outlet water from the cathode chamber is usually significantly lower than the pressure of the treated water at the inlet of the desalination chamber. Therefore, a pump is needed to pressurize the outlet water from the cathode chamber. When pressurizing using a pump, the hydrogen bubbles contained in the outlet water from the cathode chamber may cause so-called air entrainment in the pump. To prevent air entrainment, although it is considered to pump water after receiving the outlet water from the cathode chamber into a tank, hydrogen present above the solubility diffuses into the atmosphere when the outlet water is received into the tank, thus reducing the hydrogen utilization efficiency. In contrast, in the water treatment device of the first embodiment, the outlet water from the cathode chamber is directly used as the inlet water to the dissolved oxygen removal chamber. That is, the flow of the treated water is configured such that the dissolved oxygen removal chamber and the cathode chamber are connected in series. With this configuration, a pump for pressurization is not required, and the escape of hydrogen generated in the cathode chamber is not caused, thereby improving the hydrogen utilization efficiency. If the amount of hydrogen in the outlet water of the cathode chamber is insufficient to remove dissolved oxygen, hydrogen can be injected, for example, into the pipeline connecting the outlet of the cathode chamber and the inlet of the dissolved oxygen removal chamber. Even if the hydrogen generated in the cathode chamber is not used to remove dissolved oxygen, hydrogen-containing treated water can be supplied to the dissolved oxygen removal chamber by installing a unit for supplying hydrogen to the treated water upstream of the dissolved oxygen removal chamber.

[0019] Stoichiometrically, the mass of hydrogen reacting with oxygen is one-eighth the mass of oxygen, or 0.125 times. Based on this, in the first water treatment method, regardless of the method used to add hydrogen to the treated water, it is preferable to adjust the amount of hydrogen contained in the treated water supplied to the dissolved oxygen removal chamber so that the mass ratio of the amount of hydrogen supplied to the dissolved oxygen removal chamber per unit time to the dissolved oxygen load of the target substance in the treated water is 0.1 or more and 0.4 or less.

[0020] The water treatment apparatus of the first type typically allows for the removal of dissolved oxygen in the desalination chamber of the EDI unit. Therefore, it is preferable that the dissolved oxygen removal chamber is divided by an ion exchange membrane, which allows for efficient desalination of the treated water. Alternatively, the anode or cathode chamber of the EDI unit can be used as the dissolved oxygen removal chamber, in which case the dissolved oxygen removal chamber is divided by an electrode plate serving as the anode or an electrode plate serving as the cathode.

[0021] According to a second aspect of the present invention, a water treatment method is a method for at least removing dissolved oxygen from the water to be treated, comprising: applying a direct current between an anode disposed in an anode chamber and a cathode disposed in a cathode chamber filled with an ion exchanger; and introducing the water to be treated into the cathode chamber, wherein at least a portion of the ion exchanger filling the cathode chamber is an ion exchanger supported on a metal catalyst. In this water treatment method, the steps of applying a direct current between the anode and the cathode and introducing the water to be treated into the cathode chamber can be performed simultaneously or separately.

[0022] The water treatment apparatus implementing the second method has an anode chamber and a cathode chamber. The anode chamber has an anode, and the cathode chamber has a cathode. Both are filled with ion exchangers and supplied with water to be treated. At least a portion of the ion exchangers filled in the cathode chamber are ion exchangers carrying a metal catalyst. A direct current is applied between the anode and the cathode.

[0023] In the second type of water treatment apparatus, the cathode chamber is preferably separated from the anode chamber by an ion exchange membrane. This separation allows ions captured by the ion exchanger in the cathode chamber to move to the outside of the cathode chamber via the ion exchange membrane, regenerating the ion exchanger in the cathode chamber and thus maintaining dissolved oxygen removal performance over a long period. More specifically, it is preferable to use anion exchange resin or similar anion exchanger to fill the cathode chamber, and an anion exchange membrane to separate the cathode chamber. With this configuration, anions in the treated water, such as carbonate or bicarbonate ions, are adsorbed onto the anion exchanger. Then, hydroxide ions generated by the electrolysis of water at the cathode regenerate the anion exchanger, and the free anions move to the outside of the cathode chamber via the anion exchange membrane. As a result, desalination of the treated water with respect to anions such as carbonate and bicarbonate ions is performed in the cathode chamber. That is, in the cathode chamber, not only is dissolved oxygen removed from the treated water, but decarbonation is also performed.

[0024] In the case of performing the dissolved oxygen removal process in the cathode chamber of a conventional EDI device, this removal process is carried out independently of the desalination process in the desalination chamber of the EDI device. Therefore, by using an existing EDI device and employing an ion exchanger supported on a metal catalyst as the ion exchanger filling its cathode chamber, the water treatment device of the second embodiment can be easily realized. In this case, treated water different from the water targeted for dissolved oxygen removal can be introduced into the desalination chamber of the EDI device. Alternatively, the treated water, after dissolved oxygen has been removed from the cathode chamber, can be introduced into the desalination chamber for desalination.

[0025] In both the first method described above, the metal catalyst supported on the ion exchanger filling the dissolved oxygen removal chamber, and in the second method, the metal catalyst filling the cathode chamber, can be any catalyst that promotes the reaction from hydrogen and oxygen to water. Examples of such metal catalysts include iron, copper, manganese, palladium, and platinum. Among these, platinum group metal catalysts not only promote the oxygen reduction reaction but also exhibit high catalytic activity for the decomposition of hydrogen peroxide, making them suitable for applications where the water being treated contains hydrogen peroxide. Platinum group metal catalysts refer to catalysts containing one or more metals selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum. Platinum group metal catalysts can contain any one of these metal elements alone or in combination of two or more. Platinum, palladium, and platinum / palladium alloys are preferred as platinum group metal catalysts due to their high catalytic activity.

[0026] Invention Effects

[0027] Based on the above method, dissolved oxygen and other substances in the water being treated can be removed efficiently with a simple structure. Attached Figure Description

[0028] Figure 1 This is a diagram showing a water treatment apparatus based on the first embodiment.

[0029] Figure 2 This is a diagram showing another example of a water treatment device.

[0030] Figure 3 This is a diagram showing another example of a water treatment device.

[0031] Figure 4 This is a diagram showing another example of a water treatment device.

[0032] Figure 5A This is a diagram showing another example of a water treatment device.

[0033] Figure 5B This is a diagram showing another example of a water treatment device.

[0034] Figure 5C This is a diagram showing another example of a water treatment device.

[0035] Figure 6A This is a diagram showing another example of a water treatment device.

[0036] Figure 6B This is a diagram showing another example of a water treatment device.

[0037] Figure 7 This is a diagram showing another example of a water treatment device.

[0038] Figure 8This is a diagram showing a water treatment apparatus based on the second embodiment.

[0039] Figure 9 This is a diagram showing another example of a water treatment device.

[0040] Figure 10 This is a diagram showing a water treatment device consisting of an EDI (Electronic Diffusion) unit.

[0041] Figure 11 This is a diagram showing another example of a water treatment device constructed as an EDI device.

[0042] Figure 12 This is a flowchart illustrating an example of a water treatment system equipped with water treatment devices.

[0043] Figure 13 This is a flowchart illustrating another example of a water treatment system equipped with water treatment devices.

[0044] Figure 14 This is a flowchart illustrating another example of a water treatment system equipped with water treatment devices.

[0045] Figure 15 This is a diagram showing the water treatment apparatus of Comparative Example 1.

[0046] Figure 16 It is a graph showing the relationship between current density and dissolved oxygen removal rate.

[0047] Figure 17 It is a graph showing the relationship between power consumption and dissolved oxygen removal rate.

[0048] Figure 18 It is a graph showing the relationship between the current per unit dissolved oxygen load and the dissolved oxygen removal rate.

[0049] Figure 19 This is a graph showing the relationship between space velocity and dissolved oxygen removal rate in Pd-supported anion exchange resin.

[0050] Figure 20 It is a graph showing the relationship between current density and dissolved oxygen removal rate. Detailed Implementation

[0051] Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This describes the basic structure of a water treatment apparatus based on the first embodiment of the present invention.

[0052] Figure 1The water treatment apparatus shown is a device for removing dissolved oxygen and desalinizing water. Similar to conventional EDI devices, it includes an anode chamber 21 with an anode 11 and a cathode chamber 25 with a cathode 12. Between the anode chamber 21 and cathode chamber 25, sequentially arranged from the anode chamber 21 side, are a concentration chamber 22, a dissolved oxygen removal chamber 23, and a concentration chamber 24. The anode chamber 21 and concentration chamber 22 are separated by a cation exchange membrane 31; the concentration chamber 22 and dissolved oxygen removal chamber 23 are separated by an anion exchange membrane 32; the dissolved oxygen removal chamber 23 and concentration chamber 24 are separated by a cation exchange membrane 33; and the concentration chamber 24 and cathode chamber 25 are separated by anion exchange membrane 34. The anode chamber 21 is filled with cation exchange resin (CER) as a cation exchanger, and the concentration chambers 22 and 24 and the cathode chamber 25 are filled with anion exchange resin (AER) as an anion exchanger. An ion exchanger with a metal catalyst supported on its surface is packed in a single bed in the dissolved oxygen removal chamber 23. In this embodiment, a palladium (Pd)-supported anion exchange resin is filled in a single-bed manner in the dissolved oxygen removal chamber 23. In the following description, the palladium (Pd)-supported anion exchange resin will be referred to as Pd-supported anion exchange resin (Pd AER).

[0053] The treated water is supplied to the cathode chamber 25, and the outlet water of the cathode chamber 25 is directly supplied to the inlet of the dissolved oxygen removal chamber 23. Treated water, having undergone desalination and dissolved oxygen removal, is discharged from the dissolved oxygen removal chamber 23. Supply water is supplied to the concentration chambers 22 and 24, and the outlet water of the concentration chambers 22 and 24 is supplied to the anode chamber 21. The outlet water of the anode chamber 21 is discharged to the outside of the water treatment device. The supply water is not particularly limited; for example, it can be water obtained by removing turbidity and oxidizing substances from municipal water, industrial water, groundwater, etc., and then treating it through a reverse osmosis membrane device. Alternatively, the supply water in the anode chamber 21 may not be the outlet water (concentrated water) of the concentration chambers 22 and 24, but rather flow directly. The treated water may also be supplied to the dissolved oxygen removal chamber 23 from a different pipeline than the outlet water of the cathode chamber 25.

[0054] Next, regarding the use Figure 1The removal of dissolved oxygen in the water treatment apparatus shown will be explained. A direct current is applied between the anode 11 and the cathode 12, and while supply water is being supplied to the concentration chambers 22 and 24, treated water is supplied to the cathode chamber 25. In the cathode chamber 25, hydrogen is generated by a cathode reaction on the surface of the cathode 12 using the direct current, thus the treated water discharged from the cathode chamber 25 as outlet water contains hydrogen. This hydrogen is not only dissolved in the treated water but can also be dispersed in the treated water as tiny bubbles. The hydrogen-containing treated water then flows directly into the dissolved oxygen removal chamber 23. On the surface of the Pd-supported anion exchange resin (Pd AER) filling the dissolved oxygen removal chamber 23, dissolved oxygen in the treated water reacts with hydrogen to generate water. The amount of dissolved oxygen in the treated water that reacts with hydrogen is reduced. Because the reaction rate of hydrogen and oxygen is high in the presence of palladium as a metal catalyst, if the treated water contains a sufficient amount of hydrogen, treated water with sufficient dissolved oxygen removal is discharged from the cathode chamber 25. If hydrogen is present in the dissolved oxygen removal chamber 23, dissolved oxygen is removed. Therefore, considering the residence time of the treated water in the dissolved oxygen removal chamber 23 and the cathode chamber 25, dissolved oxygen removal can be achieved even if a direct current is applied intermittently between the anode 11 and the cathode 12. Furthermore, the treated water can be intermittently introduced into the dissolved oxygen removal chamber 23 while a direct current is applied continuously or intermittently.

[0055] Since the Pd-supported anion exchange resin is an anion exchanger, the dissolved oxygen removal chamber 23 filled with Pd-supported anion exchange resin functions similarly to the desalination chamber in a conventional EDI unit, and desalination of the treated water also takes place in the dissolved oxygen removal chamber 23. For example, carbonate ions (CO3-) in the treated water... 2- ), bicarbonate ions (HCO3) - Anions such as OH- are captured by Pd-supported anion exchange resin. On the surface of the cation exchange membrane 33 on the dissolved oxygen removal chamber 23 side, hydroxide ions (OH-) are also generated by the dissociation of water. - Therefore, the anions captured by the Pd-supported anion exchange resin (Pd AER) are released through ion exchange with hydroxide ions and move using the electric field between the anode 11 and the cathode 12, moving through the anion exchange membrane 32 to the concentration chamber 22. Then, the anions that have moved to the concentration chamber 22 are discharged to the outside of the device through the anode chamber 21 along with the flow of the supply water in the concentration chamber 22.

[0056] Since Pd-supported anion exchange resin can also decompose hydrogen peroxide, hydrogen peroxide can also be removed from the water being treated in the water treatment apparatus of this embodiment. When the Pd-supported anion exchange resin decomposes hydrogen peroxide, the decomposition products are hydrogen and oxygen. The generated oxygen reacts with hydrogen in the presence of the Pd-supported anion exchange resin to form water, so even if hydrogen peroxide is decomposed and removed, the dissolved oxygen concentration will not increase.

[0057] Figure 2 This represents another example of a water treatment apparatus according to the first embodiment. Figure 2 The water treatment device shown is similar to Figure 1 The water treatment apparatus shown is the same, except that the dissolved oxygen removal chamber 23 has a multi-bed structure and the Pd-supported anion exchange resin is only installed on the upstream side of the flow in the dissolved oxygen removal chamber 23. Figure 1 The water treatment apparatus shown is different. In the dissolved oxygen removal chamber 23, an anion exchange resin (AER) without a metal catalyst is filled on the downstream side of the flow. Since the reaction rate of hydrogen and oxygen in the presence of Pd-supported anion exchange resin is sufficiently high, even if Pd-supported anion exchange resin is filled in a mixed bed configuration as part of the dissolved oxygen removal chamber 23, dissolved oxygen in the treated water can be sufficiently removed. When Pd-supported anion exchange resin is configured in a mixed bed configuration in the dissolved oxygen removal chamber 23, as long as there is no substance other than Pd-supported anion exchange resin in the area where Pd-supported anion exchange resin is configured (i.e., a single bed configuration), a layer of Pd-supported anion exchange resin can be filled at any position in the dissolved oxygen removal chamber 23. In this case, it is natural to prevent the generation of treated water that flows inside the dissolved oxygen removal chamber 23 without passing through the layer of Pd-supported anion exchange resin. Figure 2 The structure shown can reduce the amount of expensive palladium catalyst used, thus reducing costs.

[0058] Figure 3 This represents another example of a water treatment device. Figure 3 The water treatment device shown is similar to Figure 2 The water treatment device shown is the same, but similar to... Figure 2 The difference in the water treatment device shown is that the ion exchanger filled in the downstream region of the dissolved oxygen removal chamber 23, which is a mixed-bed system, is not an anion exchange resin without a metal catalyst, but a cation exchange resin (CER) without a metal catalyst.

[0059] Figure 4 This represents another example of a water treatment device. Figure 4 The water treatment device shown is similar to Figure 2 The water treatment device shown is the same, but similar to... Figure 2The difference in the water treatment apparatus shown is that, in the downstream region of the dissolved oxygen removal chamber 23, which is a mixed bed, anion exchange resin without metal catalyst and cation exchange resin without metal catalyst are filled in a mixed bed (MB) manner.

[0060] exist Figures 1 to 4 In the water treatment apparatus shown, a desalination chamber is arranged between the anode 11 and the cathode 12, adjacent to the dissolved oxygen removal chamber 23 on either the cathode or anode side, separated by an intermediate ion exchange membrane. This allows effluent from the dissolved oxygen removal chamber 23 to flow into the desalination chamber, or effluent from the cathode chamber 25 to flow into the desalination chamber and then supply it to the dissolved oxygen removal chamber 23. The desalination chamber is filled with an ion exchange medium. The intermediate ion exchange membrane can be an anion exchange membrane, a cation exchange membrane, or a composite membrane such as a bipolar membrane. This configuration further improves the overall desalination performance of the water treatment apparatus.

[0061] Figure 5A This illustrates an example of a water treatment device with a desalination chamber located adjacent to the dissolved oxygen removal chamber 23. Figure 5A The water treatment device shown is, in Figure 1 The water treatment apparatus shown includes a desalination chamber 26 positioned between the dissolved oxygen removal chamber 23 and the concentration chamber 24. The dissolved oxygen removal chamber 23 and the desalination chamber 26 are separated by a cation exchange membrane 35, which serves as an intermediate ion exchange membrane. The desalination chamber 26 and the concentration chamber 24 are separated by a cation exchange membrane 33. The desalination chamber 26 is filled with cation exchange resin. The effluent from the cathode chamber 25 is first supplied to the dissolved oxygen removal chamber 23, and then to the desalination chamber 26. Dissolved oxygen is removed from the desalination chamber 26, and the treated water flows out after desalination.

[0062] Figure 5B The water treatment device shown is, in Figure 5A In the water treatment apparatus shown, feed water is directly supplied to the anode chamber 21 instead of supplying the outlet water from the concentration chambers 22 and 24 to the anode chamber 21. Furthermore, treated water supplied from a different pipeline than the treated water supplied to the cathode chamber 25 is supplied together with the outlet water from the cathode chamber 25 to the dissolved oxygen removal chamber 23. By supplying treated water from other pipelines to the dissolved oxygen removal chamber 23, the treated water treatment capacity of the water treatment apparatus as a whole is improved. Electrode water is discharged from the anode chamber 21, and concentrated water is discharged from the concentration chambers 22 and 24.

[0063] The ion exchange membrane that can be used as an intermediate ion exchange membrane to separate the dissolved oxygen removal chamber 23 and the desalination chamber 26 is not limited to a cation exchange membrane. Figure 5C The water treatment device shown is, in Figure 5AThe water treatment apparatus shown uses an anion exchange membrane 36 as an intermediate ion exchange membrane to separate the dissolved oxygen removal chamber 23 and the desalination chamber 26, and the desalination chamber 26 is configured as a multi-bed water treatment device. In the desalination chamber 26, the inlet side is filled with cation exchange resin (CER) without metal catalyst, and the outlet side is filled with anion exchange resin (AER) without metal catalyst.

[0064] Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5A , Figure 5B and Figure 5C The water treatment device shown has the same structure as a conventional EDI device, except that it uses the desalination chamber as a dissolved oxygen removal chamber, and can perform both desalination and dissolved oxygen removal within the dissolved oxygen removal chamber. In a conventional EDI device, multiple desalination chambers can be arranged between the anode and cathode. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5A , Figure 5B and Figure 5C In the water treatment apparatus shown, the structure consisting of anion exchange membrane 32, dissolved oxygen removal chamber 23, cation exchange membrane 33 and concentration chamber 24 is also used as a repeating unit. By arranging multiple such repeating units between the concentration chamber 22 adjacent to the anode chamber 21 and the anion exchange membrane 34 dividing the cathode chamber 25, multiple dissolved oxygen removal chambers 23 can be arranged between the anode 11 and the cathode 12.

[0065] Figure 6A The water treatment device shown is in Figure 1 The water treatment device shown is equipped with multiple dissolved oxygen removal chambers 23. The outlet water of the cathode chamber 25 is distributed and introduced into the multiple dissolved oxygen removal chambers 23 in parallel. Desalinated water that has undergone desalination treatment and has had dissolved oxygen removed is discharged from each dissolved oxygen removal chamber 23.

[0066] Figure 6B The water treatment device shown is, in Figure 6A In the water treatment apparatus shown, feed water is directly supplied to the anode chamber 21 instead of the outlet water from the concentration chambers 22 and 24. Furthermore, the treated water, supplied from a different pipeline than the treated water supplied to the cathode chamber 25, is supplied together with the outlet water from the cathode chamber 25 to the dissolved oxygen removal chamber 23. Electrode water is discharged from the anode chamber 21, and concentrated water is discharged from the concentration chambers 22 and 24.

[0067] In the water treatment apparatus based on the present invention, the cathode chamber itself can function as a dissolved oxygen removal chamber, and in this case, it is not necessary to provide a dissolved oxygen removal chamber separately from the cathode chamber. Hereinafter, as a second embodiment, a water treatment apparatus in which the cathode chamber itself functions as a dissolved oxygen removal chamber will be described. Figure 7 This describes the basic structure of a water treatment apparatus based on a second embodiment of the present invention.

[0068] Figure 7 The water treatment apparatus shown includes: an anode chamber 21 with an anode 11, a concentration chamber 24 separated from the anode chamber 21 by a cation exchange membrane 31, and a cathode chamber 25 with a cathode 12 and separated from the concentration chamber 24 by an anion exchange membrane 34. The anode chamber 21 is filled with a cation exchange resin (CER) as a cation exchanger, and the concentration chamber 24 is filled with anion exchange resin (AER) as an anion exchanger. The cathode chamber 25 is filled with an ion exchanger with a metal catalyst supported on its surface. Specifically, the cathode chamber 25 is filled with a single bed of Pd-supported anion exchange resin. Treated water containing dissolved oxygen is supplied to the cathode chamber 25, passing through it. Feed water is supplied to the concentration chamber 24, and the outlet water of the concentration chamber 24 is directly supplied to the anode chamber 21. The feed water passing through the anode chamber 21 is discharged from the anode chamber 21 as wastewater. There are no particular limitations on the water supply. For example, it can be water obtained by removing turbidity and oxidizing substances from municipal water, industrial water, groundwater, etc., and then treating it using a reverse osmosis membrane device.

[0069] exist Figure 7 In the water treatment apparatus shown, a direct current is applied between the anode 11 and the cathode 12, and while supply water is being supplied to the concentration chamber 24, treated water is supplied to the cathode chamber 25. In the cathode chamber 25, hydrogen is generated by a cathode reaction on the surface of the cathode 12 using the direct current. This hydrogen reacts with dissolved oxygen in the treated water on the surface of the Pd-supported anion exchange resin (Pd AER), resulting in water production. The amount of dissolved oxygen in the treated water that reacts with hydrogen is reduced. The reaction rate of hydrogen with oxygen is high in the presence of palladium as a metal catalyst; therefore, if a sufficient amount of hydrogen is produced, treated water with sufficiently removed dissolved oxygen is discharged from the cathode chamber 25. As a result, treated water with sufficiently removed dissolved oxygen is discharged from the cathode chamber 25. If hydrogen is present in the cathode chamber 25, dissolved oxygen is removed; therefore, considering the residence time of the treated water in the cathode chamber 25, a direct current can be applied intermittently between the anode 11 and the cathode 12. Furthermore, treated water can be intermittently introduced into the dissolved oxygen removal chamber 23 while a direct current is applied continuously or intermittently.

[0070] Since the Pd-supported anion exchange resin is an anion exchanger, in the cathode chamber 25, carbonate ions (CO3-) in the water being treated are used as the exchange medium.2- ), bicarbonate ions (HCO3) - Anions, such as hydroxyl (OH-) ions, are captured by Pd-supported anion exchange resin. Hydroxide ions (OH-) are also generated through the cathode reaction at cathode 12. - Therefore, the anions captured by the Pd-supported anion exchange resin are released through ion exchange with hydroxide ions, move by the electric field between the anode 11 and the cathode 12, and move through the anion exchange membrane 34 to the concentration chamber 24. Then, the anions that have moved to the concentration chamber 24 are discharged to the outside of the device through the anode chamber 21 along with the flow of the supply water in the concentration chamber 24. That is, in Figure 7 In the water treatment apparatus shown, desalination of anions is also performed in the cathode chamber 25. Furthermore, since the Pd-supported anion exchange resin can also decompose hydrogen peroxide, in this water treatment apparatus, [the process is similar to]... Figure 1 Similarly, the water treatment device shown in Figure 6 can also remove hydrogen peroxide from the water being treated.

[0071] By using Pd-supported anion exchange resin, hydrogen peroxide can also be removed from the water being treated in the water treatment apparatus of this embodiment. When the Pd-supported anion exchange resin decomposes hydrogen peroxide, the decomposition products are hydrogen and oxygen. The generated oxygen reacts with hydrogen in the presence of the Pd-supported anion exchange resin to form water; therefore, even if hydrogen peroxide is decomposed and removed, the dissolved oxygen concentration does not increase. Furthermore, in Figure 7 In the water treatment apparatus shown, the anode chamber 21 can also function as the concentration chamber 24. In this case, simply removing the cation exchange membrane 31 will create a structure in which the anode chamber 21 and the concentration chamber 24 are integrated.

[0072] Figure 8 This represents another example of a water treatment apparatus in the second embodiment. Figure 8 The water treatment device shown is similar to Figure 7 The water treatment device shown is the same, but similar to... Figure 7 The difference in the water treatment apparatus shown is that the cathode chamber 25 has a mixed-bed structure, and the Pd-supported anion exchange resin is only placed on the downstream side of the flow within the cathode chamber 25. In the cathode chamber 25, the upstream side of the flow is filled with anion exchange resin (AER) without a metal catalyst. The cathode reaction in the cathode chamber 25 takes place on the entire surface of the cathode 12. Furthermore, because the reaction rate of hydrogen and oxygen in the presence of the Pd-supported anion exchange resin is sufficiently high, even if the Pd-supported anion exchange resin is only placed on the outlet side of the cathode chamber 25, dissolved oxygen in the treated water can be sufficiently removed. Figure 8In the structure shown, the cost can be reduced by decreasing the amount of expensive palladium catalyst used. To further reduce the amount of Pd-supported anion exchange resin used, it is also considered to fill the cathode chamber 25 in a mixed-bed manner with other anion exchange resins and cation exchange resins. However, to improve hydrogen utilization efficiency, it is preferable that at least a portion of the cathode chamber 25 is filled with Pd-supported anion exchange resin in a single-bed manner. That is, when filling the cathode chamber 25 with Pd-supported anion exchange resin, it is preferable to fill it in a single-bed or mixed-bed manner.

[0073] Figure 7 and Figure 8 The water treatment apparatus shown is a structure of a conventional EDI apparatus with the desalination chamber removed. However, in the water treatment apparatus of the second embodiment, a desalination chamber may be provided and the structure may be the same as that of a conventional EDI apparatus. Desalination treatment is performed in the desalination chamber and dissolved oxygen removal treatment is performed in the cathode chamber. Figure 9 This refers to a water treatment apparatus as a second embodiment of an EDI device. Figure 9 The water treatment device shown is, in Figure 7 In the water treatment apparatus shown, a concentration chamber 22 and a desalination chamber 26 are sequentially arranged between the anode chamber 21 and the concentration chamber 24, starting from the anode chamber 21 side. The anode chamber 21 and the concentration chamber 22 are separated by a cation exchange membrane 31, the concentration chamber 22 and the desalination chamber 26 are separated by an anion exchange membrane 32, and the desalination chamber 26 and the concentration chamber 24 are separated by a cation exchange membrane 33. The concentration chamber 22 is filled with anion exchange resin (AER), and the desalination chamber 26 is filled with a mixed bed (MB) containing both cation exchange resin and anion exchange resin. The desalination chamber 26 is supplied with treated water that is different from the treated water for which dissolved oxygen removal is performed. Feed water is supplied to the anode chamber 21, concentration chambers 22 and 24; electrode water is discharged from the anode chamber 21, and concentrated water is discharged from the concentration chambers 22 and 24.

[0074] exist Figure 9 In the water treatment apparatus shown, by applying a direct current between the anode 11 and the cathode 12, the water to be treated is desalinated in the desalination chamber 26, similar to the desalination chamber in a conventional EDI device, and the desalinated water is discharged from the desalination chamber 26. On the other hand, in the cathode chamber 25, the water is desalinated... Figure 7 Similarly, in the water treatment apparatus shown, dissolved oxygen is removed from the water being treated, and the treated water, after dissolved oxygen removal, is discharged from the cathode chamber 25. At this time, as described above, hydrogen peroxide contained in the water being treated is also removed.

[0075] Figure 10 This is another example of a water treatment apparatus configured as a second embodiment of an EDI device. Figure 10The water treatment device shown is for... Figure 9 The treated water discharged from the cathode chamber 25 of the water treatment device shown is directly supplied to the water treatment device in the desalination chamber 26. Therefore, according to Figure 10 The water treatment device shown can produce desalinated water with dissolved oxygen and hydrogen peroxide removed.

[0076] Typically, multiple desalination chambers can be arranged between the anode and cathode in an EDI device. Figure 9 and Figure 10 In the water treatment apparatus shown, the structure consisting of anion exchange membrane 32, desalination chamber 26, cation exchange membrane 33 and concentration chamber 24 is used as a repeating unit. By arranging multiple such repeating units between the concentration chamber 22 adjacent to the anode chamber 21 and the anion exchange membrane 34 dividing the cathode chamber 25, multiple desalination chambers 26 can be arranged between the anode 11 and the cathode 12. Figure 11 The water treatment device shown is, in Figure 10 The water treatment apparatus shown is equipped with multiple desalination chambers 26. The treated water discharged from the cathode chamber 25 is distributed and introduced into the multiple desalination chambers 26 in parallel. Desalinated water, which has had dissolved oxygen removed and undergone desalination treatment, is discharged from each desalination chamber 26.

[0077] While the water treatment apparatus based on various embodiments of the present invention has been described above, these water treatment apparatuses can be assembled into water treatment systems that produce pure or ultrapure water. Water treatment systems that produce pure or ultrapure water are, for example, composed of: activated carbon (AC) devices, reverse osmosis (RO) membrane devices, ultraviolet (UV) irradiation devices, ion exchange resin devices (IER) devices, membrane degassing devices (MD), EDI devices, non-regenerative ion exchange devices (CP), and various filters. The water treatment apparatus based on the present invention can perform dissolved oxygen removal, hydrogen peroxide removal, desalination, etc., and therefore can be used to replace one or more of the membrane degassing device, ion exchange resin device, EDI device, and non-regenerative ion exchange device, or can be installed before or after the membrane degassing device, ion exchange resin device, EDI device, and non-regenerative ion exchange device to improve the removal performance of impurities. Figure 12 This illustrates an example of a water treatment system equipped with a water treatment apparatus based on the present invention.

[0078] Figure 12 The water treatment system shown is a system that generates ultrapure water from raw water such as municipal water. It consists of a primary pure water system that generates primary pure water from raw water and a subsystem that generates ultrapure water from primary pure water. In the diagram, symbol 100 indicates the use of... Figures 1 to 11Any of the water treatment devices described herein. In a primary pure water system, a raw water tank 41, a first reverse osmosis membrane unit 51, a second reverse osmosis membrane unit 52, a reverse osmosis membrane treated water tank 42, an ultraviolet irradiation device (UV) 55, and a water treatment device 100 are sequentially arranged to treat the raw water, resulting in the production of primary pure water. If the water treatment device 100 based on the present invention is not used, an ion exchange resin unit, an EDI unit, or a non-regenerative ion exchange unit is provided instead of the water treatment device 100, and a membrane degassing unit is further provided. In the primary pure water system, when the downstream equipment, which serves as the destination for pure water supply, is full, the produced primary pure water is circulated in the reverse osmosis membrane treated water tank 42.

[0079] In the subsystem, a pure water tank 45 is provided to store primary pure water from the primary pure water system. At the outlet of the pure water tank 45, an ultraviolet irradiation device (UV) 61, a non-regenerative ion exchange device (CP) 63, a membrane degassing device (MD) 65, and an ultrafiltration membrane (UF) 67 are sequentially configured to process the primary pure water and produce ultrapure water. A portion of the produced ultrapure water is circulated in the pure water tank 45. A precision filtration membrane can also be used instead of the ultrafiltration membrane (UF) 67. Furthermore, in the subsystem, a water treatment device based on the present invention can be provided instead of the non-regenerative ion exchange device 63 and the membrane degassing device 65, or it can be provided before or after the non-regenerative ion exchange device 63 and the membrane degassing device 65. When membrane degassing devices are provided in both the primary pure water system and the subsystem, sometimes multiple membrane degassing devices are connected in series to improve the overall dissolved oxygen removal rate. However, when multiple membrane degassing devices are connected in series, some of the membrane degassing devices can be replaced with the water treatment device based on the present invention.

[0080] Figure 13 This represents another example of a water treatment system equipped with a water treatment apparatus based on the present invention. Figure 13 The water treatment system shown is, in Figure 12 In the water treatment system shown, the water treatment device 100 is positioned before the ultraviolet irradiation device 55 of the primary pure water system, and a treatment device (IER / EDI) 56, serving as an ion exchange resin device or an EDI device, is positioned after the ultraviolet irradiation device 55. Water from the reverse osmosis membrane treatment tank 42 is sequentially passed through the water treatment device 100, the ultraviolet irradiation device 55, and the treatment device 56 of this invention, and primary pure water is discharged from the treatment device 56, which serves as an ion exchange resin device or an EDI device. It is known that when total organic carbon (TOC) is decomposed and removed by irradiating the treated water with ultraviolet light in the ultraviolet irradiation device 55, the TOC removal rate decreases if the dissolved oxygen concentration in the treated water is high. Therefore, in Figure 13The water treatment system shown can reduce the dissolved oxygen concentration in the inlet water of the ultraviolet irradiation device 55, and can improve the TOC removal rate in the ultraviolet irradiation device when the dissolved oxygen concentration in the raw water is high.

[0081] Figure 14 This represents another example of a water treatment system equipped with a water treatment apparatus based on the present invention. Figure 14 The water treatment system shown is, in Figure 12 In the water treatment system shown, a water treatment system based on the water treatment device 100 of the present invention is also arranged between the outlet of the ultraviolet irradiation device 61 and the inlet of the non-regenerative ion exchange device 63 of the subsystem. Although carbonate ions, bicarbonate ions, etc. are generated when organic matter in water is decomposed and removed by ultraviolet irradiation, the water treatment device 100 can also remove carbonate ions and bicarbonate ions, therefore, as Figure 12 As shown, by configuring the water treatment device 100 within the subsystem, the processing load in the downstream non-regenerative ion exchange device 63 can be reduced, thereby improving the performance of impurity removal.

[0082] Example

[0083] The present invention will now be described in more detail through examples and comparative examples.

[0084] [Example 1]

[0085] As an example 1, assembly Figure 1 The water treatment apparatus shown is as follows. The dimensions of the anode chamber 21, concentration chamber 22, concentration chamber 24, and cathode chamber 25 are all 105mm × 105mm × 9.5mm, and the dimensions of the dissolved oxygen removal chamber 23 are 105mm × 105mm × 19.5mm. In Example 1, the dissolved oxygen removal chamber 23 is filled with a single bed of Pd-supported anion exchange resin (Pd AER). The anode 11 and cathode 12 are 105mm × 105mm in size, and the current density can be calculated by dividing the applied current by the area of ​​these electrodes.

[0086] [Example 2]

[0087] As an example 2, assembly Figure 3The water treatment apparatus shown is identical in structure and size to that of Example 1, but differs in that the dissolved oxygen removal chamber 23 is filled with a mixed bed of Pd-supported anion exchange resin (Pd AER). Specifically, in the dissolved oxygen removal chamber 23 of Example 2, a layer of Pd-supported anion exchange resin (Pd AER) is disposed on the inlet side of the treated water, and a layer of cation exchange resin (CER) without metal catalyst is disposed on the outlet side of the treated water. The ratio of the flow path length in the Pd-supported anion exchange resin layer to the flow path length in the cation exchange resin layer without metal catalyst is 1:1.

[0088] [Comparative Example 1]

[0089] As a comparative example 1, the assembly was... Figure 15 The water treatment apparatus shown is identical in structure and dimensions to that of Example 1, but differs in that the dissolved oxygen removal chamber 23 is filled with a mixed bed of Pd-supported anion exchange resin and cation exchange resin without a metal catalyst. Specifically, in Comparative Example 1, the Pd-supported anion exchange resin and the cation exchange resin without a metal catalyst were mixed at a loose volume ratio of 1:1 and filled into the dissolved oxygen removal chamber 23 in a mixed state (Pd AER MB).

[0090] For the water treatment apparatuses of Examples 1, 2, and Comparative Example 1, the treated water was introduced at a flow rate of 50 L / h and the supply water was introduced at a flow rate of 5 L / h while the applied current was varied within the range of 0.5 A to 2.5 A. The changes in dissolved oxygen concentration corresponding to the current density were investigated based on the dissolved oxygen concentration of the treated water at the inlet of the cathode chamber 25 and the dissolved oxygen concentration of the treated water discharged from the dissolved oxygen removal chamber 23. The results are shown below. Figure 16 .according to Figure 16 In Comparative Example 1, where the Pd-supported anion exchange resin was packed in a mixed bed configuration, the dissolved oxygen removal rate reached its upper limit of approximately 70% even with increased current density. However, in Examples 1 and 2 (single-bed and multi-bed configurations), increasing the current density resulted in a dissolved oxygen removal rate exceeding 80%. Furthermore, according to... Figure 16 To achieve a dissolved oxygen removal rate of at least 20%, the current density is preferably set to 0.45 A / dm³. 2 Above and 2.3A / dm 2 To achieve a better dissolved oxygen removal rate, it is preferable to set the current density to 1.0 A / dm³. 2 Above 2.0A / dm 2 the following.

[0091] In a water treatment device, when the applied current between the anode 11 and the cathode 12 changes, the applied voltage also changes. The product of the current and the voltage is the power consumption, which changes with the change in the applied current. Figure 17 Indicates calculation Figure 16 The power consumption in the results shown is converted to the power consumption per unit flow rate of treated water. Figure 17 In the figure, the horizontal axis represents the power consumption per unit flow rate of treated water. However, compared to Examples 1 and 2, the power consumption of Comparative Example 1 is greater. The applied current is the same in Examples 1 and 2 as in Comparative Example 1. Therefore, in Comparative Example 1 with the mixed bed configuration, the applied voltage is higher than in Examples 1 and 2, resulting in greater power consumption required to achieve the same dissolved oxygen removal rate. In other words, in the case of the single-bed configuration shown in Example 1 and the mixed-bed configuration shown in Example 2, dissolved oxygen can be removed energy-efficiently. Following the same consideration as the preferred range of current density, the power consumption per unit flow rate of treated water is preferably 0.06 W·h / L or more and 0.70 W·h / L or less, more preferably 0.17 W·h / L or more and 0.50 W·h / L or less.

[0092] Based on the results Figure 16 The results show the dissolved oxygen concentration of the treated water at the inlet of cathode chamber 25 and the current value at that time. The relationship between the current value per dissolved oxygen load (the mass of dissolved oxygen contained in the treated water flowing in per unit time) and the dissolved oxygen removal rate was investigated. The results are shown in... Figure 18 .according to Figure 18 To achieve a dissolved oxygen removal rate of over 50%, the current value per unit dissolved oxygen load needs to be 2 mA·h / mg; to achieve a dissolved oxygen removal rate of over 80%, the current value per unit dissolved oxygen load needs to be 4 mA·h / mg. Therefore, the current value per unit dissolved oxygen load is preferably set to 2 mA·h / mg or higher and 8 mA·h / mg or lower, more preferably 4 mA·h / mg or higher and 8 mA·h / mg or lower.

[0093] With the applied current fixed at 2A, the water treatment apparatuses of Examples 1, 2, and Comparative Example 1 were operated, and the changes in dissolved oxygen removal rate when the flow rate of the treated water was varied were investigated. The results are presented as the change in dissolved oxygen removal rate relative to the space velocity based on the volume of the Pd-supported anion exchange resin within the dissolved oxygen removal chamber 23. Figure 19 .like Figure 19 As shown, the dissolved oxygen removal rate decreases with increasing flow rate of the treated water. In the single-bed mode, the space velocity of the treated water, which is the flow rate of the treated water divided by the volume of the Pd-supported anion exchange resin, is 500 h⁻¹. -1At that time, the dissolved oxygen removal rate decreased to 50%. Furthermore, it was assumed that increasing the flow rate of the treated water would decrease the dissolved oxygen removal rate. Therefore, in practical applications, the preferred space velocity of the treated water, based on the volume of the Pd-supported anion exchange resin filled in the dissolved oxygen removal chamber 23, is 1000 h⁻¹. -1 Below, 500h is more preferred. -1 the following.

[0094] [Example 3]

[0095] Using water with a dissolved oxygen concentration of 7.9 mg / L and a carbonic acid concentration of 3.2 mg / L as the treated water, the treated water was supplied to the water treatment apparatus of Example 1, which is a single-bed system, at a flow rate of 50 L / h. The applied current was set to 1.0 A, and the water treatment apparatus was operated. Then, the dissolved oxygen concentration and carbonic acid concentration in the treated water discharged from the dissolved oxygen removal chamber 23 were measured, and their respective removal rates were calculated. The results are shown in Table 1. As can be seen from Table 1, the water treatment apparatus based on the present invention can remove not only dissolved oxygen from the treated water but also carbonic acid.

[0096] [Table 1]

[0097]

[0098] [Example 4]

[0099] Water with a dissolved oxygen concentration of 7.8 mg / L to 8.2 mg / L was used as the treated water. This treated water was supplied to the water treatment apparatuses of Examples 1, 2, and Comparative Example 1 at a flow rate of 50 L / h, and each water treatment apparatus was operated with an applied current of 1.5 A. The hydrogen concentration in the outlet water of the cathode chamber 25 and the dissolved oxygen concentration in the treated water discharged from the dissolved oxygen removal chamber 23 were measured. The amount of oxygen removed in the dissolved oxygen removal chamber 23 was calculated based on the dissolved oxygen concentration of the treated water, and the utilization efficiency of the hydrogen generated in the cathode chamber 25 was calculated based on this and the hydrogen concentration in the outlet water of the cathode chamber. In the calculation, it was assumed that 1 mole of hydrogen (H2) reacted with 0.5 moles of oxygen (O2). The results are shown in Table 2.

[0100] [Table 2]

[0101]

[0102] Comparing Example 2 (compared to the mixed-bed method) with Comparative Example 1 (compared to the mixed-bed method), although the amount of Pd-supported anion exchange resin in the dissolved oxygen removal chamber 23 is the same, the hydrogen utilization efficiency of Comparative Example 1 (compared to the mixed-bed method) is lower. On the other hand, comparing Example 2 (compared to the single-bed method) with Example 1 (compared to the single-bed method), although the amount of Pd-supported anion exchange resin in Example 1 is twice that in Example 2, no significant difference was found in the hydrogen utilization efficiency. In Examples 1 and 2, approximately all of the hydrogen generated in the cathode chamber 25 is used for dissolved oxygen removal.

[0103] [Example 5]

[0104] Assembly Figure 7 The water treatment apparatus shown has a 105mm × 105mm × 9.5mm dimension for the anode chamber 21, concentration chamber 24, and cathode chamber 25. Water with a dissolved oxygen concentration of 8.2mg / L is prepared and used as the treated water, flowing into the cathode chamber 25 at a rate of 50L / h. This water is also used as the supply water, flowing into the concentration chamber 24 at a rate of 5L / h. The water treatment apparatus is operated by varying the current flowing between the anode 11 and cathode 12 within the range of 0.5A to 2.5A. The dissolved oxygen concentration of the treated water discharged from the cathode chamber 25 is measured to determine the dissolved oxygen removal rate. The results are shown below. Figure 20 .Depend on Figure 20 It can be seen that there is a correlation between the current value and the dissolved oxygen removal rate; increasing the current density can improve the dissolved oxygen removal rate. This means that the hydrogen generated in the cathode chamber 25 is effectively utilized for dissolved oxygen removal.

[0105] [Example 6]

[0106] Using the same apparatus as in Example 5, hydrogen peroxide was added to the water to be treated, and the operating current was set to 1.5A. Otherwise, the experiment was conducted in the same manner as in Example 1, the concentration of hydrogen peroxide in the treated water was measured, and the removal rate of hydrogen peroxide was determined. The results are shown in Table 3.

[0107] [Table 3]

[0108]

[0109] As shown in Table 3, hydrogen peroxide can also be removed when Pd-supported anion exchange resin is filled into the cathode chamber 25. Furthermore, the dissolved oxygen removal rate was measured to be approximately 27%, which is the same as the dissolved oxygen removal rate in Example 5.

[0110] Symbol Explanation

[0111] 11 Anode

[0112] 12 Cathodes

[0113] 21 Anode Chamber

[0114] Concentration chambers 22 and 24

[0115] 23 Dissolved Oxygen Removal Chamber

[0116] 25 Cathode Chamber

[0117] 26 Desalination Chamber

[0118] 31, 33, 35 cation exchange membranes

[0119] 32, 34, 36 Anion exchange membranes

[0120] 100 Water treatment equipment.

Claims

1. A water treatment method that removes at least dissolved oxygen from the water being treated. The water treatment method includes: The process of applying direct current between the anode in the anode chamber and the cathode in the cathode chamber; as well as The process of introducing the water to be treated into a dissolved oxygen removal chamber, which is disposed between the anode chamber and the cathode chamber and filled with an ion exchanger and is independently located from the cathode chamber. At least a portion of the ion exchangers filling the dissolved oxygen removal chamber are ion exchangers supported on a metal catalyst. An ion exchanger carrying the metal catalyst is filled in a single bed manner in at least a portion of the dissolved oxygen removal chamber.

2. The water treatment method according to claim 1, wherein, The treated water is supplied to the cathode chamber, and the treated water after passing through the cathode chamber is then introduced into the dissolved oxygen removal chamber.

3. The water treatment method according to claim 1 or 2, wherein, The metal catalyst is a platinum group metal catalyst, which removes dissolved oxygen and hydrogen peroxide from the water being treated.

4. A water treatment method that removes at least dissolved oxygen and hydrogen peroxide from the water to be treated. The water treatment method includes: A process of applying direct current between an anode disposed in an anode chamber and a cathode disposed in a cathode chamber filled with ion exchanger; as well as The process of introducing the water to be treated into the cathode chamber and obtaining treated water from the cathode chamber after the removal of dissolved oxygen and hydrogen peroxide. The cathode chamber is divided by an ion exchange membrane on the side of the anode chamber, and the anode chamber is divided by an ion exchange membrane on the side of the cathode chamber. At least one of a concentration chamber and a desalination chamber is disposed between the anode chamber and the cathode chamber. At least a portion of the ion exchangers filling the cathode chamber are ion exchangers supported on a metal catalyst. An ion exchanger carrying the metal catalyst is filled in a single bed manner in at least a portion of the cathode chamber.

5. The water treatment method according to claim 4, wherein, The ion exchange membrane that divides the cathode chamber is an anion exchange membrane, and the ion exchange medium filling the cathode chamber is an anion exchange medium.

6. The water treatment method according to claim 4 or 5, wherein, The water treatment method further includes a step of desalinating the water to be treated by introducing the water that has passed through the cathode chamber into a desalination chamber that is divided by an ion exchange membrane between the anode chamber and the cathode chamber and is filled with ion exchangers.

7. The water treatment method according to claim 4 or 5, wherein, The metal catalyst is a platinum group metal catalyst, which removes dissolved oxygen and hydrogen peroxide from the water being treated.

8. A water treatment apparatus that at least removes dissolved oxygen from the water being treated. The water treatment device has the following features: Anode and cathode; and A dissolved oxygen removal chamber, independently configured between the anode chamber (where the anode is located) and the cathode chamber (where the cathode is located), is filled with ion exchangers and is used to circulate the water to be treated. At least a portion of the ion exchangers filling the dissolved oxygen removal chamber are ion exchangers supported on a metal catalyst. An ion exchanger carrying the metal catalyst is filled in a single-bed configuration in at least a portion of the dissolved oxygen removal chamber. A direct current is applied between the anode and the cathode.

9. The water treatment apparatus according to claim 8, wherein, The dissolved oxygen removal chamber is divided by one or more of the electrode plate serving as the anode and the ion exchange membrane.

10. The water treatment apparatus according to claim 8 or 9, wherein, The dissolved oxygen removal chamber is connected in series with the cathode chamber along the flow direction of the water being treated.

11. The water treatment apparatus according to claim 8 or 9, wherein, A unit for supplying hydrogen to the water being treated is provided upstream of the dissolved oxygen removal chamber.

12. The water treatment apparatus according to claim 8 or 9, wherein, The DC current value relative to the dissolved oxygen load of the object being treated in the water being treated is set to be 2 mA·h / mg or more and 8 mA·h / mg or less.

13. The water treatment apparatus according to claim 8 or 9, wherein, The space velocity of the treated water, based on the volume of the ion exchanger carrying the metal catalyst filling the dissolved oxygen removal chamber, is set to 1000 h⁻¹. -1 the following.

14. The water treatment apparatus according to claim 8 or 9, wherein, The amount of hydrogen contained in the water to be treated supplied to the dissolved oxygen removal chamber is adjusted so that the mass ratio of the amount of hydrogen supplied to the dissolved oxygen removal chamber per unit time to the dissolved oxygen load of the object to be treated in the water is 0.1 or more and 0.4 or less.

15. The water treatment apparatus according to claim 8 or 9, wherein, The current density in the dissolved oxygen removal chamber is 0.45 A / dm³. 2 Above and 2.3A / dm 2 the following.

16. The water treatment apparatus according to claim 8 or 9, wherein, The power consumption per unit flow rate of the treated water in the dissolved oxygen removal chamber is above 0.06 W·h / L and below 0.70 W·h / L.

17. A water treatment device, comprising: Anode chamber, which includes an anode; and The cathode chamber, which has a cathode and is filled with ion exchangers, is supplied with the water to be treated. The cathode chamber is divided by an ion exchange membrane on the side of the anode chamber, and the anode chamber is divided by an ion exchange membrane on the side of the cathode chamber. At least one of a concentration chamber and a desalination chamber is disposed between the anode chamber and the cathode chamber. At least a portion of the ion exchanger filling the cathode chamber is an ion exchanger supported on a platinum group metal catalyst. An ion exchanger supporting the platinum group metal catalyst is packed in at least a portion of the cathode chamber in a single-bed configuration. A direct current is applied between the anode and the cathode to obtain treated water from the cathode chamber, after the dissolved oxygen and hydrogen peroxide in the treated water have been removed.

18. The water treatment apparatus according to claim 17, wherein, The ion exchange membrane that defines the cathode chamber is an anion exchange membrane, and the ion exchange medium filling the cathode chamber is an anion exchange medium.

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