Electrodeionized water production apparatus and water treatment method

Abstract

This invention provides an electro-deionized water production apparatus that processes alkaline ammonia-containing water to produce pure water with a resistivity of 1 MΩ·cm or higher. [Solution] The electric deionized water production apparatus 10 has a cation exchange membrane 32 and an anion exchange membrane 31 placed between the anode 11 and the cathode 12, and has a plurality of compartments partitioned by these exchange membranes. The plurality of compartments include at least one compartment 20 which has at least one desalination chamber 22 filled with a cation exchanger. The water to be treated, which is ammonia-containing water with a pH of 9 to 12, is supplied to the desalination chamber 22, and a DC current is applied between the anode 11 and the cathode 12. When the water flow rate per chamber of the desalination chamber 22 is F [L / h] and the current applied to the anode 11 and the cathode 12 is I [A], the value of (I ÷ F) is 0.05 to 0.8 [A·h / L].

Description

Technical Field

[0001] The present invention relates to an electrodeionization deionized water production apparatus (EDI (Electrodeionization) apparatus) and a water treatment method using said electrodeionization deionized water production apparatus. Background Art

[0002] In water treatment facilities used in power plants, semiconductor factories and the like, electrodialysis apparatuses (ED (Electrodialysis) apparatuses) are generally used to remove ammonia components from water to be treated. In an ED apparatus, cation exchange membranes and anion exchange membranes are alternately arranged between an anode and a cathode to form a desalination chamber and a concentration chamber. With this configuration, the ED apparatus performs desalination and concentration of ionic substances in water to be treated by utilizing the selective permeability (charge repulsion) of ion exchange membranes and the action of electricity (electrophoresis) resulting from energization. With this type of ED apparatus, when the conductivity of the water flowing through the apparatus is low, energization becomes difficult, which may lead to a decrease in the water quality of desalinated treated water. For this reason, ED apparatuses are suitably used for treating wastewater and the like that contain a large amount of ionic components in the solution.

[0003] Patent Document 1 discloses a removal method in which an acid is added to condensate demineralization reclaimed water containing ammonia nitrogen in a power plant to produce acidic condensate demineralization reclaimed water containing ammonium salt, and the produced condensate demineralization reclaimed water is subjected to an ED apparatus to reduce ammonium ions. The pH value of the produced condensate demineralization reclaimed water is adjusted to 2 to 4, and the concentration of ammonium ions contained in said condensate demineralization reclaimed water is also high (for example, about 1000 ppm). Therefore, the conductivity of the condensate demineralization reclaimed water is high. In addition, the concentration ratio of the concentration chamber of the ED apparatus is set to several tens of times.

[0004] Patent Document 2 describes an ammonia removal device for removing ammonia from hydrogen-rich reformed gas supplied to a polymer electrolyte fuel cell. In this ammonia removal device, ammonia-containing wash water is supplied to an ED device, and the wash water from which ammonia has been removed by the ED device is circulated back to the ammonia remover. Furthermore, as a related technology for ammonia removal devices, Patent Document 3 describes a low concentration of ammonia after an ammonia absorption device, approximately 0.65 to 1.2 ppm. These technologies require reducing the ammonia concentration to 5 ppb to 0.1 ppm or less.

[0005] Patent Document 4 describes an ED (Emission Decontamination) apparatus for treating ammonium salt-containing wastewater. In this ED apparatus, ammonium salt-containing wastewater is supplied to a desalination chamber, acid-containing water is extracted from an anion concentration chamber, and ammonia water is extracted from a cation concentration chamber. The ammonia water extracted from the cation concentration chamber is returned to the cation concentration chamber after carbon dioxide gas is injected into it. By injecting carbon dioxide gas into the ammonia water to produce ammonium carbonate, the conductivity of the liquid passing through the cation concentration chamber can be increased.

[0006] Patent Document 5 describes a method for treating wastewater containing ammonia generated in the recovery process of liquid crystal and semiconductor manufacturing plants. In this wastewater treatment method, the wastewater containing ammonia (ammonia-containing water) is subjected to ion exchange treatment, reverse osmosis membrane treatment, or electrolytic deionization treatment. This yields a treated solution with a high ammonia concentration of about 1700 ppm. This treated solution is then electrolytically treated to decompose and remove the ammonia. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 7-80254 [Patent Document 2] Japanese Patent Publication No. 2005-317419 [Patent Document 3] Japanese Patent Publication No. 2003-31247 [Patent Document 4] Japanese Patent Publication No. 2011-224445 [Patent Document 5] Japanese Patent Publication No. 2007-98272 [Overview of the project] [Problems that the invention aims to solve]

[0008] For example, treated water from a wastewater treatment facility may be used to produce pure water, which is then used as water for equipment (analyzers, etc.) within the wastewater treatment facility or as makeup water. In this case, the treated water (water to be treated) is intermediate treated water (raw water) with an conductivity of approximately tens to 250 μS / cm. Furthermore, the pH value of this intermediate treated water (raw water) is typically around 9 to 12. It is desirable to produce pure water with a resistivity of 1 MΩ·cm or higher from such low-concentration alkaline ammonia-containing water.

[0009] The technology for removing ammonia using the ED device described above is based on the premise of treating highly acidic ammonia-containing water, and is not configured to treat low-concentration alkaline ammonia-containing water as described above. When treating alkaline ammonia-containing water using an ED device, it is necessary to increase the conductivity of the water to a state where it can conduct electricity by adding electrolytes such as acid or carbon dioxide, or by circulating the solution to increase its concentration. This leads to problems such as increased operating costs and processing man-hours.

[0010] Furthermore, the form of ammonia changes depending on the pH value. Specifically, it becomes ammonium ions on the acidic side and unionized ammonia on the alkaline side. Unionized ammonia cannot be moved by electrophoresis. Therefore, when treating alkaline ammonia-containing water using an electrodialysis (ED) device, it is necessary to acidify the ammonia-containing water before performing electrodialysis. As a result, there is a problem of increased processing time.

[0011] The object of the present invention is to solve the above problems and to provide an electrolytic deionized water production apparatus and water treatment method that produce pure water with a resistivity of 1 MΩ·cm or more by treating alkaline ammonia-containing water. [Means for solving the problem]

[0012] To achieve the above objective, according to one aspect of the present invention, An electro-deionized water production apparatus that processes water to be treated, which is ammonia-containing water with a pH value of 9 to 12, to produce pure water with a resistivity of 1 MΩ·cm or more, It has multiple compartments separated by a cation exchange membrane and an anion exchange membrane between the anode and the cathode. The plurality of compartments include at least one compartment having at least one desalting chamber filled with a cation exchanger, An electro-deionized water production apparatus is provided, characterized in that the water to be treated is supplied to the desalination chamber, a direct current is applied between the anode and the cathode, and when the water flow rate per chamber of the desalination chamber is F [L / h] and the current applied to the anode and the cathode is I [A], the value of (I ÷ F) is 0.05 to 0.8 [A·h / L]. According to another aspect of the present invention, An electro-deionized water production apparatus that processes water to be treated, which is ammonia-containing water with a pH value of 9 to 12, to produce pure water with a resistivity of 1 MΩ·cm or more, It has multiple compartments separated by a cation exchange membrane and an anion exchange membrane between an anode chamber equipped with an anode and a cathode chamber equipped with a cathode, The plurality of compartments include at least one compartment consisting of a concentration chamber filled with at least an anion exchanger and at least one desalting chamber adjacent to the concentration chamber via the cation exchange membrane or the anion exchange membrane and filled with at least a cation exchanger. The water to be treated is supplied to the desalination chamber, and a portion of the desalination treated water generated in the desalination chamber is branched off and supplied to the concentration chamber and at least one of the electrode chambers of the anode chamber and the cathode chamber. An electro-deionized water production apparatus is provided, characterized in that when the total flow rate through the desalination chamber is A [L / h], and the total flow rate through the concentration chamber and the electrode chamber is B [L / h], the value of (A ÷ B) is 1 or more and 8 or less.

[0013] According to yet another aspect of the present invention, A water treatment method for producing pure water with a resistivity of 1 MΩ·cm or more by treating water to be treated, which is ammonia-containing water with a pH of 9 to 12, using an electrolytic deionized water production apparatus having a plurality of compartments separated between an anode and a cathode by a cation exchange membrane and an anion exchange membrane, wherein the plurality of compartments include at least one compartment section having at least one desalination chamber filled with at least a cation exchanger, and the apparatus has a plurality of compartments separated between an anode and a cathode by a cation exchange membrane and an anion exchange membrane, wherein the plurality of compartments include at least one compartment section having at least one desalination chamber filled with at least a cation exchanger, A water treatment method is provided, which involves supplying the water to be treated to the desalination chamber while applying a direct current between the anode and the cathode, operating the electric deionized water production apparatus such that the value of (I÷F) is 0.05 to 0.8 [A·h / L] when the flow rate of water per chamber of the desalination chamber is F [L / h] and the current applied to the anode and the cathode is I [A]. According to yet another aspect of the present invention, A water treatment method for producing pure water with a resistivity of 1 MΩ·cm or more by using an electrolytic deionized water production apparatus which has a plurality of compartments separated by a cation exchange membrane and an anion exchange membrane between an anode chamber equipped with an anode and a cathode chamber equipped with a cathode, wherein the plurality of compartments include at least one compartment consisting of a concentration chamber filled with at least an anion exchanger and at least one desalination chamber adjacent to the concentration chamber via the cation exchange membrane or the anion exchange membrane and filled with at least a cation exchanger, and by treating water to be treated which is ammonia-containing water with a pH of 9 to 12, the apparatus comprising: There is provided a water treatment method comprising supplying the water to be treated to the desalination chamber, branching a part of the desalinated water produced by the desalination chamber to supply the water to the concentration chamber and at least one electrode chamber of the anode chamber and the cathode chamber, setting a total flow rate of water passing through the desalination chamber as A [L / h], setting a total of a flow rate of water passing through the concentration chamber and a flow rate of water passing through the electrode chamber as B [L / h], and operating the electric deionized water production apparatus such that a value of (A÷B) is 1 or more and 8 or less. Effects of the Invention

[0014] According to the present invention, there can be provided an electric deionized water production apparatus that can suppress increases in operating costs and treatment man-hours, and produces pure water having a resistivity of 1 MΩ·cm or more by treating low-concentration alkaline ammonia-containing water. Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram showing the configuration of the electric deionized water production apparatus according to the first embodiment of the present invention. [Figure 2] It is a schematic diagram showing an example of a water flow of the electric deionized water production apparatus shown in FIG. 1. [Figure 3] It is a diagram for explaining morphological changes of ammonia according to pH change. [Figure 4] It is a schematic diagram for explaining diffusion of ammonia. [Figure 5] It is a schematic diagram showing the configuration of the electric deionized water production apparatus according to the second embodiment of the present invention. [Figure 6] It is a schematic diagram showing the configuration of the electric deionized water production apparatus according to the third embodiment of the present invention. [Figure 7] It is a schematic diagram showing the configuration of the electric deionized water production apparatus according to the fourth embodiment of the present invention. [Figure 8] It is a graph showing a relationship between water quality and a current value with respect to a flow rate per desalination chamber. [Figure 9] It is a graph showing a relationship between water quality and a flow rate ratio of water passing through the desalination chamber and the concentration chamber. [Figure 10] This graph shows the relationship between water quality and the SV (Saturation Velocity) of the water flow in the desalination chamber. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the components described in the embodiments are merely examples and are not intended to limit the scope of the present invention to them.

[0017] (First Embodiment) Figure 1 is a schematic diagram showing the configuration of an electrolytic deionized water production apparatus according to a first embodiment of the present invention. In Figure 1, solid arrows indicate piping (or flow paths). Where two pipes intersect, it indicates that they are not connected and are intersecting while separated from each other.

[0018] The electrodeionized water production apparatus (EDI apparatus) 10 shown in Figure 1 is configured to produce pure water with a resistivity of 1 MΩ·cm or higher by treating water to be treated, which is alkaline ammonia-containing water with a pH of 9 to 12. Operating conditions are also set for the electrodeionized water production apparatus (EDI apparatus) 10. The EDI apparatus 10 has anion exchange membranes 31 and cation exchange membranes 32 alternately arranged between the anode 11 and the cathode 12. It has multiple compartments separated by the anion exchange membranes 31 and cation exchange membranes 32.

[0019] The multiple compartments include at least one compartment 20, each consisting of a concentration chamber 24 and a desalination chamber 22 adjacent to the concentration chamber 24 via an anion exchange membrane 31 or a cation exchange membrane 32. In this embodiment, a concentration chamber 24, a desalination chamber 22 adjacent to the concentration chamber 24 on the anode side via a cation exchange membrane 32, and a desalination chamber 22 adjacent to the concentration chamber 24 on the cathode side via an anion exchange membrane 31 are provided between an anode chamber 21 equipped with an anode 11 and a cathode chamber 23 equipped with a cathode 12. An anion exchange membrane 31 is provided between the anode chamber 21 and the desalination chamber 22. A cation exchange membrane 32 is provided between the cathode chamber 23 and the desalination chamber 22. In the example shown in Figure 1, the compartment 20 consists of one concentration chamber 24 and two desalination chambers 22. One compartment 20 is located between the anode chamber 21 and the cathode chamber 23, but this is not limited to that. The number of compartments 20 may be two or more.

[0020] The concentration chamber 24 is filled with at least anion exchange material, and the desalination chamber 22 is filled with at least a cation exchange material. In this embodiment, the desalination chamber 22 is filled with anion exchange resin (AER), which is an anion exchange material, and cation exchange resin (CER), which is a cation exchange material, for example, in a mixed bed form. The concentration chamber 24 is filled with anion exchange resin, for example, in a single bed form. Similarly, the cathode chamber 23 is filled with anion exchange resin in a single bed form. The anode chamber 21 is filled with layers of anion exchange resin and layers of cation exchange resin that are interconnected. Within the anode chamber 21, the layer of anion exchange resin is arranged so as not to contact the anode 11 but to contact the anion exchange film 31, and the layer of cation exchange resin is arranged so as not to contact the anion exchange film 31 but to contact the anode 11.

[0021] In the EDI device 10 of this embodiment, the water to be treated is supplied to each desalination chamber 22. The water to be treated is, for example, treated water from a wastewater treatment facility, which is alkaline ammonia-containing water with a pH of 9 to 12. A portion of the desalination treated water produced in each desalination chamber 22 is branched off and supplied to the concentration chamber 24 and the anode chamber 21, respectively.

[0022] In the anode chamber 21, hydrogen ions generated by the electrode reaction are released into the water at the point where the cation exchange resin and the anion exchange resin come into contact. The electrode water generated in the anode chamber 21 is supplied to the cathode chamber 23 together with the concentrated water generated in the concentration chamber 24. In this embodiment, the flow direction of the water to be treated in the desalination chamber 22 and the flow direction of the desalination treated water in the concentration chamber 24 are countercurrent, but this is not limited to this. The flow direction of the water to be treated in the desalination chamber 22 and the flow direction of the desalination treated water in the concentration chamber 24 may be the same. In addition, a portion of the desalination treated water generated in each desalination chamber 22 may be branched and supplied to the concentration chamber 24 and at least one of the electrode chambers of the anode chamber 21 and cathode chamber 23. For example, a portion of the desalination treated water may be supplied to the concentration chamber 24 and the cathode chamber 23 respectively, and the electrode water generated in the cathode chamber 23 may be supplied to the anode chamber 21 together with the concentrated water generated in the concentration chamber 24.

[0023] To set the operating conditions of the EDI device 10, flow meters with alarm contacts (FIA) 40, 41, a flow meter (FI) 42, a resistivity meter (RI) 43, a conductivity meter (CI) 44, and valves 50-52 are provided. Valve 50 and flow meter with alarm contacts 40 are installed in piping 60 for supplying treated water to each desalination chamber 22, and are set, for example, to a flow rate of treated water of 85 ml / min (5.1 L / h). Valve 51 and flow meter with alarm contacts 41 are installed in piping 62 that branches off from piping 61 connected to the outlet of each desalination chamber 22 and supplies desalination treated water to the anode chamber 21 and the concentration chamber 24, and are set, for example, to a flow rate of desalination treated water of 60 ml / min (3.6 L / h). Valve 52, flow meter 42, and resistivity meter 43 are installed in piping 61, and are set, for example, to a flow rate of desalination treated water of 25 ml / min (1.5 L / h). The conductivity meter 44 is installed in the piping 63 connected to the outlet of the cathode chamber 23.

[0024] More specifically, the water flow of the EDI device 10 is configured as shown in Figure 2. In this water flow, in addition to the aforementioned flow meters 40 and 41 with alarm contacts, flow meter 42, resistometer 43, conductivity meter 44, and valves 50 to 52, conductivity meter 45, flow meter 46, and pressure gauges (PI) 47 to 48 are also provided. Conductivity meter 45 and pressure gauge 47 are provided in piping 60. Flow meter 46 is provided in piping 62 together with conductivity meter 44. Pressure gauge 48 is provided in piping 62 together with flow meter device 41 with alarm contacts. Pressure gauge 49 is provided in piping 61 together with flow meter 42 and resistometer 43. Using these flow meters 40 and 41 with alarm contacts, flow meters 42 and 46, resistometer 43, conductivity meters 44 and 45, pressure gauges (PI) 47 to 48, and valves 50 to 52, it is possible to appropriately set the operating conditions of the EDI device 10. Note that the water flow configuration shown in Figure 2 is just one example and is not limited to it. The water flow configuration can be changed as appropriate.

[0025] Next, the operation of the EDI device 10 of this embodiment will be described. Alkaline ammonia-containing water (water to be treated) with a pH of 9 to 12 is supplied to each desalination chamber 22 while a direct current is applied between the anode 11 and the cathode 12. Desalination treatment is performed in each desalination chamber 22, and concentration treatment is performed in the concentration chamber 24, and the operating conditions are set so that pure water with a Ω·cm or higher is produced as desalination treated water.

[0026] The water to be treated by the EDI device 10 in this embodiment is alkaline ammonia-containing water with a pH of 9 to 12. The conductivity of this water to be treated is, for example, 40 to 300 μS / cm. Such water to be treated has properties that make it unsuitable for treatment using an ED device due to its low conductivity, but unsuitable for treatment using an EDI device due to its large amount of ions to be treated.

[0027] Furthermore, the form of ammonia changes with pH. Specifically, as shown in Figure 3, ammonium ions (NH4) form on the acidic side. +This results in unionized ammonia (NH3) on the alkaline side. Unionized ammonia cannot be moved by electrophoresis. Therefore, when treating alkaline ammonia-containing water using an electrodialysis apparatus, it was necessary to acidify the ammonia-containing water before performing electrodialysis. In addition, electrolytes such as acids and carbon dioxide were added, or the solution was circulated to increase its concentration, thereby increasing the conductivity of the water to a state where it could conduct electricity.

[0028] In contrast, the compartment 20 of the EDI device 10 in this embodiment is filled with an ion exchange resin that acts as a conductor. Therefore, even if the conductivity of the fluid is low, current can be passed between the anode 11 and the cathode 12. As a result, the addition and circulation of electrolytes required in ED devices are unnecessary.

[0029] Furthermore, the EDI device 10 of this embodiment includes the following characteristic components and operating conditions in order to produce pure water with a resistivity of 1 MΩ·cm or higher.

[0030] (1) Current value relative to the flow rate per desalination chamber The flow rate of water passing through the EDI device 10 is reduced, and the ratio of current to load is increased. Specifically, if the flow rate of water per chamber of the desalination chamber 22 is F [L / h], and the current applied to the anode 11 and cathode 12 is I [A], the value of (I ÷ F) is set to be in the range of 0.05 to 0.8 [A·h / L]. In a typical EDI device, the value of (I ÷ F) is around 0.025 to 0.05 [A·h / L], but in the EDI device 10 of this embodiment, the water quality of the desalination treated water can be improved by increasing the value of (I ÷ F).

[0031] (2) Filling with ion exchange resin If the current value is increased, the ammonium ions that have moved to the concentration chamber 24 will diffuse into the adjacent desalination chamber 22 due to the action of the current.

[0032] To explain in more detail, as shown in Figure 4, in the concentration chamber 24, the pH profile changes from acidic to alkaline from the anode 11 side to the cathode 12 side. In other words, in the concentration chamber 24, the region closer to the anode 11 is acidic, and the region closer to the cathode 12 is alkaline. Ammonium ions (NH4) in the desalination chamber 22 + The ammonium ions are moved by electricity and permeate the cation exchange membrane 32. The ammonium ions that have permeated the cation exchange membrane 32 move towards the cathode 12 within the concentration chamber 24. The ammonium ions moving within the concentration chamber 24 are converted to ammonia (uncharged free NH3) near the anion exchange membrane 31. The freed ammonia can easily permeate the anion exchange membrane 31 without being subject to selective permeability (charge repulsion). The ammonia that has permeated the anion exchange membrane 31 diffuses within the desalination chamber 22, resulting in a decrease in the water quality of the desalination treated water in the desalination chamber 22.

[0033] In the EDI device 10 of this embodiment, anion exchange resin is filled into the concentration chamber 24. This suppresses the accumulation of ammonium ions in the concentration chamber 24, and as a result, the water quality of the desalination treatment water can be improved.

[0034] (3) Flow rate of water supplied to the desalination chamber and concentration chamber (+ electrode chamber) As shown in Figure 4, ammonium ions become ammonia (undissociated) on the alkaline side. Therefore, the exclusion mechanism by charge repulsion of the anion exchange membrane 31 ceases to function, and ammonium ions easily diffuse from the concentration chamber 24 to the desalination chamber 22. In the EDI device 10 of this embodiment, when the total flow rate through the desalination chamber 22 is A [L / h] and the total flow rate through the concentration chamber 24 and the anode chamber 21 is B [L / h], the value of (A ÷ B) is set to be between 1 and 8. This allows the concentration ratio of the concentration chamber 24 to be kept low, and the water quality of the desalination treated water can be improved. In a configuration where a portion of the desalination treated water is supplied to the concentration chamber 24 and the cathode chamber 23, respectively, and electrode water generated in the cathode chamber 23 is supplied to the anode chamber 21 together with the concentrated water, the total flow rate through the concentration chamber 24 and the cathode chamber 23 is B [L / h]. Furthermore, in a configuration where a portion of the desalination treatment water is branched off and supplied to the concentration chamber 24 and both electrode chambers (anode chamber 21 and cathode chamber 23), the total amount of the flow rate through the concentration chamber 24 and the flow rate through both electrode chambers is B [L / h].

[0035] (4) Water flow SV (space velocity) in the desalination chamber The water flow rate SV (space velocity) per unit volume of the desalination chamber 22 indicates how many times the apparent volume of water passes through the ion exchange resin per unit time. If the water flow rate SV per unit volume of the desalination chamber 22 is too slow, it becomes difficult to dilute the ammonia diffused in the desalination chamber 22, resulting in a decrease in the quality of the desalination treated water. Conversely, if the water flow rate SV per unit volume of the desalination chamber 22 is too fast, the removal function in the desalination chamber 22 cannot keep up. As a result, the quality of the desalination treated water decreases. In the EDI device 10 of this embodiment, the water flow rate SV per unit volume of the desalination chamber 22 is 15-50 [h -1 It is set within the range of [ ]. This allows for improvement of the water quality of the desalination treatment water.

[0036] (5) Flow direction between the desalination chamber and the concentration chamber In the EDI device 10 of this embodiment, the flow direction of the water to be treated in the desalination chamber 22 and the flow direction of the desalination treatment water in the concentration chamber 24 are set to be counterflow directions. As a result, for example, the residence time of ammonia in the concentration chamber 24 shown in Figure 4 is shortened, and as a result, the diffusion of ammonia into the desalination chamber is suppressed, and the water quality of the desalination treatment water can be improved.

[0037] By operating the system with the above-mentioned "(1) current value relative to the flow rate per desalination chamber" and / or "(3) flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber," pure water with a resistivity of 1 MΩ·cm or higher can be produced. Furthermore, by combining at least one of the above-mentioned "(2) filling of ion exchange resin," "(4) water flow SV (space velocity) in the desalination chamber," and "(5) flow direction between the desalination chamber and the concentration chamber," pure water with a resistivity of 1 MΩ·cm or higher can be produced more reliably.

[0038] The EDI device 10 of this embodiment can maximize the reduction in operating costs and processing man-hours by being applied to water treatment facilities, particularly wastewater treatment facilities, used in places such as power plants and semiconductor factories. For example, treated wastewater, especially alkaline water containing a low concentration of ammonia, can be supplied to the EDI device 10, and the pure water produced using the EDI device 10 can be used as water for various equipment within the wastewater treatment facility or as makeup water.

[0039] Some factories have both wastewater treatment facilities and pure water production facilities. However, such factories require the installation of pure water lines from the pure water production facility to the wastewater treatment facility, which incurs significant costs. The EDI device 10 of this embodiment can be installed within the wastewater treatment facility, thus reducing costs. In a water treatment apparatus that performs water treatment using the EDI device 10 of this embodiment, a non-regenerative ion exchange device (also called a cartridge polisher (CP)) may be added to the outlet of the desalination chamber 22 (for example, the piping 61 on which the valve 52, flow meter 42, and resistivity meter 43 are provided). In this water treatment apparatus, the outlet water from the desalination chamber 22 is supplied to the non-regenerative ion exchange device. The outlet water of the non-regenerative ion exchange device is the treated water (deionized water) from this water treatment apparatus. Alternatively, a reverse osmosis membrane separator (RO device) may be added to the inlet of the desalination chamber 22 (for example, the piping 60 equipped with an alarm contact flow meter 40 and a conductivity meter 45).

[0040] (Second embodiment) Figure 5 is a schematic diagram showing the configuration of an electrolytic deionized water production apparatus according to a second embodiment of the present invention. The EDI apparatus 10A of this embodiment has the same configuration as the EDI apparatus 10 of the first embodiment, except that the configuration of the desalination chamber 22 is different. The same reference numerals are used for components that are the same as those in the EDI apparatus 10 of the first embodiment, and their detailed descriptions are omitted.

[0041] In the EDI apparatus 10A of this embodiment, each desalination chamber 22 is equipped with an intermediate ion exchange membrane 33 located between the anion exchange membrane 31 and the cation exchange membrane 32. In this embodiment, the intermediate ion exchange membrane 33 is composed of a cation exchange membrane. Hereinafter, the intermediate ion exchange membrane 33 will be referred to as the cation exchange membrane 33.

[0042] Each desalination chamber 22 is divided by a cation exchange membrane 33 into a first small desalination chamber 26 located closer to the anode 11 and a second small desalination chamber 27 located closer to the cathode 12. The first small desalination chamber 26 is filled with at least an anion exchanger, and the second small desalination chamber 27 is filled with at least a cation exchanger. An anion exchange resin is used as the anion exchanger. A cation exchange resin is used as the cation exchanger.

[0043] The first and second small desalination chambers 26 and 27 are connected in such a way that the water to be treated is supplied to one of the two small desalination chambers, and the water flowing out of the first small desalination chamber flows into the other small desalination chamber. In this embodiment, the water to be treated is supplied to the second small desalination chamber 27, and the water flowing out of the second small desalination chamber 27 is supplied to the first small desalination chamber 26.

[0044] In the desalination chamber 22 located on the anode 11 side of the concentration chamber 24, the first small desalination chamber 26 is adjacent to the anode chamber 21 via an anion exchange membrane 31, and the second small desalination chamber 27 is adjacent to the concentration chamber 24 via a cation exchange membrane 32. On the other hand, in the desalination chamber 22 located on the cathode 12 side of the concentration chamber 24, the first small desalination chamber 26 is adjacent to the concentration chamber 24 via an anion exchange membrane 31, and the second small desalination chamber 27 is adjacent to the cathode chamber 23 via a cation exchange membrane 32. The desalination treated water flowing out of the first small desalination chamber 26 of each desalination chamber 22 merges, and then a portion is branched off and supplied to the concentration chamber 24 and the anode chamber 21.

[0045] In the desalination chamber 22 located on the anode 11 side of the concentration chamber 24, the flow direction of the treated water in the second small desalination chamber 27 and the flow direction of the desalination treatment water in the concentration chamber 24 are countercurrent. In the desalination chamber 22 located on the cathode 12 side of the concentration chamber 24, the flow direction of the treated water in the first small desalination chamber 26 and the flow direction of the desalination treatment water in the concentration chamber 24 are countercurrent. Note that the flow direction of the treated water in the first small desalination chamber 26 and the second small desalination chamber 27 may be the same as the flow direction of the desalination treatment water in the concentration chamber 24.

[0046] In the EDI device 10A of this embodiment, pure water with a resistivity of 1 MΩ·cm or higher can be produced by setting the aforementioned "(1) current value relative to the flow rate per desalination chamber" and / or "(3) flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber" and operating the device. Furthermore, by further combining at least one of the aforementioned "(2) filling of ion exchange resin", "(4) water flow SV (space velocity) in the desalination chamber", and "(5) flow direction between the desalination chamber and the concentration chamber", pure water with a resistivity of 1 MΩ·cm or higher can be produced more reliably.

[0047] Furthermore, in the EDI device 10 of the first embodiment, the desalination chamber 22 is filled with anion exchange resin and cation exchange resin, which is a cation exchange agent, in a mixed bed configuration. In contrast, in the EDI device 10A of this embodiment, in the desalination chamber 22, the first small desalination chamber 26 is filled with anion exchange resin in a single bed configuration, and the second small desalination chamber 27 is filled with cation exchange resin in a single bed configuration. By filling the ion exchange resin in a single bed configuration in this way, the electrical resistance value of the EDI device 10A can be made lower than that of the EDI device 10.

[0048] In each desalination chamber 22, the order in which water flows through the first small desalination chamber 26 and the second small desalination chamber 27 is not limited to the order shown in Figure 5. The water to be treated may be supplied to the first small desalination chamber 26, and the water flowing out of the first small desalination chamber 26 may be supplied to the second small desalination chamber 27. In this case, a portion of the desalination treated water flowing out of the second small desalination chamber 27 is branched off and supplied to the concentration chamber 24. In a water treatment apparatus that performs water treatment using the EDI device 10A of this embodiment, a non-regenerative ion exchange device (CP) may be added to the outlet of the desalination chamber 22 (for example, the piping 61 on which the valve 52, flow meter 42, and resistivity meter 43 are provided). In this water treatment apparatus, the outlet water from the desalination chamber 22 is supplied to the non-regenerative ion exchange device. The outlet water of the non-regenerative ion exchange device is the treated water (deionized water) from this water treatment apparatus. Alternatively, a reverse osmosis membrane separator (RO device) may be added to the inlet of the desalination chamber 22 (for example, the piping 60 on which the flow meter 40 with an alarm contact is installed).

[0049] (Third embodiment) Figure 6 is a schematic diagram showing the configuration of an electrolytic deionized water production apparatus according to a third embodiment of the present invention. The EDI apparatus 10B of this embodiment has the same configuration as the EDI apparatus 10 of the first embodiment, except that the configuration of the concentration chamber is different. The same reference numerals are used for components that are the same as those in the EDI apparatus 10 of the first embodiment, and their detailed descriptions are omitted.

[0050] In the EDI device 10B shown in Figure 6, the anode chamber 21 itself functions as a concentration chamber, and the cathode chamber 23 also functions as a concentration chamber; therefore, the concentration chamber 24 shown in Figure 1 is not provided.

[0051] The water to be treated is supplied to the desalination chamber 22. A portion of the desalination water from the desalination chamber 22 is branched off and supplied to the anode chamber 21, and the water that has passed through the anode chamber 21 is then supplied to the cathode chamber 23. In the anode chamber 21, hydrogen ions generated by the electrode reaction are released into the water at the point where the cation exchange resin and the anion exchange resin come into contact, so water containing hydrogen ions is supplied to the cathode chamber 23. As a result, the inside of the cathode chamber 23 becomes an acidic atmosphere, which prevents the formation of scale inside the cathode chamber 23. Alternatively, a portion of the desalination water may be branched off and supplied to at least one of the electrode chambers, the anode chamber 21 and the cathode chamber 23. For example, a portion of the desalination water may be branched off and supplied to the cathode chamber 23, and the water that has passed through the cathode chamber 23 may then be supplied to the anode chamber 21.

[0052] In the EDI device 10B of this embodiment, pure water with a resistivity of 1 MΩ·cm or higher can be produced by setting the aforementioned "(1) current value relative to the flow rate per desalination chamber" and / or "(3) flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber" and operating the device. However, regarding "(3) flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber," in this embodiment, the total flow rate through the desalination chamber 22 is set to A [L / h], and the total flow rate through the anode chamber 21 is set to B [L / h], so that the value of (A ÷ B) is between 1 and 8. Furthermore, by further combining at least one of the aforementioned "(2) filling of ion exchange resin," "(4) water flow SV (space velocity) in the desalination chamber," and "(5) flow direction between the desalination chamber and the concentration chamber," pure water with a resistivity of 1 MΩ·cm or higher can be produced more reliably. In a configuration where a portion of the desalination water is branched off and supplied to the cathode chamber 23, and the water that has passed through the cathode chamber 23 is then supplied to the anode chamber 21, the total flow rate through the cathode chamber 23 is B [L / h]. Also, in a configuration where a portion of the desalination water is branched off and supplied to both electrode chambers (anode chamber 21 and cathode chamber 23), the total flow rate through both electrode chambers is B [L / h].

[0053] In the water treatment apparatus that performs water treatment using the EDI device 10B of this embodiment, a non-regenerative ion exchange device (CP) may be added to the outlet of the desalination chamber 22. In this water treatment apparatus, the outlet water from the desalination chamber 22 is supplied to the non-regenerative ion exchange device. The outlet water of the non-regenerative ion exchange device is the treated water (deionized water) from this water treatment apparatus. Additionally, a reverse osmosis (RO) membrane separator may be added to the inlet of the desalination chamber 22 (for example, the piping for supplying the treated water to the desalination chamber 22).

[0054] (Fourth embodiment) Figure 7 is a schematic diagram showing the configuration of an electrolytic deionized water production apparatus according to a fourth embodiment of the present invention. The EDI apparatus 10C of this embodiment has the same configuration as the EDI apparatus 10B of the third embodiment, except that the configuration of the desalination chamber 22 is different. Components identical to those of the EDI apparatus 10B are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0055] In the EDI apparatus 10C of this embodiment, the desalination chamber 22 includes an intermediate ion exchange membrane 33 located between the anion exchange membrane 31 and the cation exchange membrane 32. In this embodiment, the intermediate ion exchange membrane 33 is composed of a cation exchange membrane. Hereinafter, the intermediate ion exchange membrane 33 will be referred to as the cation exchange membrane 33.

[0056] The desalination chamber 22 is divided by a cation exchange membrane 33 into a first small desalination chamber 26 located closer to the anode 11 and a second small desalination chamber 27 located closer to the cathode 12. The first small desalination chamber 26 is filled with at least an anion exchanger. The second small desalination chamber 27 is filled with at least a cation exchanger. An anion exchange resin is used as the anion exchanger, and a cation exchange resin is used as the cation exchanger.

[0057] The first and second small desalination chambers 26 and 27 are connected in such a way that the water to be treated is supplied to one of the two small desalination chambers, and the water flowing out of the first small desalination chamber flows into the other small desalination chamber. In this embodiment, the water to be treated is supplied to the second small desalination chamber 27, and the water flowing out of the second small desalination chamber 27 is supplied to the first small desalination chamber 26.

[0058] In the desalination chamber 22, the first small desalination chamber 26 is adjacent to the anode chamber 21 via an anion exchange membrane 31, and the second small desalination chamber 27 is adjacent to the cathode chamber 23 via a cation exchange membrane 32. A portion of the desalination water discharged from the first small desalination chamber 26 of the desalination chamber 22 is branched off and supplied to the anode chamber 21.

[0059] In the desalination chamber 22, the flow direction of the water to be treated in the first small desalination chamber 26 and the flow direction of the electrode water in the anode chamber 21 are counterflowing, and the flow direction of the water to be treated in the second small desalination chamber 27 and the flow direction of the electrode water in the cathode chamber 23 are counterflowing. However, the flow direction of the water to be treated in the first small desalination chamber 26 and the flow direction of the electrode water in the anode chamber 21 may be parallel. Similarly, the flow direction of the water to be treated in the second small desalination chamber 27 and the flow direction of the electrode water in the cathode chamber 23 may be parallel.

[0060] In the EDI device 10C of this embodiment, by setting the aforementioned "(1) current value relative to the flow rate per desalination chamber" and / or "(3) flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber" and operating the device, pure water with a resistivity of 1 MΩ·cm or higher can be produced. However, regarding "(3) flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber," as in the third embodiment, in this embodiment as well, the total flow rate through the desalination chamber 22 is set to A [L / h] and the total flow rate through the anode chamber 21 is set to B [L / h], so that the value of (A ÷ B) is between 1 and 8. Furthermore, by further combining at least one of the aforementioned "(2) filling of ion exchange resin," "(4) water flow SV (space velocity) in the desalination chamber," and "(5) flow direction between the desalination chamber and the concentration chamber," pure water with a resistivity of 1 MΩ·cm or higher can be produced more reliably. In a configuration where a portion of the desalination water is branched off and supplied to the cathode chamber 23, and the water that has passed through the cathode chamber 23 is then supplied to the anode chamber 21, the total flow rate through the cathode chamber 23 is B [L / h]. Also, in a configuration where a portion of the desalination water is branched off and supplied to both electrode chambers (anode chamber 21 and cathode chamber 23), the total flow rate through both electrode chambers is B [L / h].

[0061] In the water treatment apparatus that performs water treatment using the EDI device 10C of this embodiment, a non-regenerative ion exchange device (CP) may be added to the outlet of the desalination chamber 22. In this water treatment apparatus, the outlet water from the desalination chamber 22 is supplied to the non-regenerative ion exchange device. The outlet water of the non-regenerative ion exchange device is the treated water (deionized water) from this water treatment apparatus. Additionally, a reverse osmosis (RO) membrane separator may be added to the inlet of the desalination chamber 22 (for example, the piping for supplying the treated water to the desalination chamber 22).

[0062] Next, the present invention will be described in more detail by reference to examples.

[0063] [Example 1] The relationship between the aforementioned "(1) Current value relative to the flow rate per desalination chamber" and the water quality of the desalination treated water was investigated. In this example, the EDI device 10A shown in Figure 5 was used to measure voltage [V], current [A], flow rate at inlet A of desalination chamber 22 [L / h], flow rate at inlet B of concentration chamber 24 (+ anode chamber 21) [L / h], water quality (Din [μS / cm] and Dout [MΩ·cm]), and current value relative to the flow rate per desalination chamber (I ÷ F). The measurement results are shown in Table 1.

[0064] [Table 1]

[0065] Figure 8 plots the relationship between water quality and the current value (I÷F) relative to the flow rate per desalination chamber, based on the results in Table 1 above. As can be seen from the results in Figure 8, increasing the value of (I÷F) improves water quality, but increasing the value of (I÷F) too much actually decreases water quality. Based on this characteristic, it was found that by setting the value of (I÷F) within the range of 0.05 to 0.8 [A·h / L], it is possible to produce pure water with a resistivity of 1 MΩ·cm or higher.

[0066] [Example 2] The relationship between the aforementioned "(3) Flow rate ratio of water flowing through the desalination chamber and the concentration chamber + electrode chamber" and the water quality of the desalination treated water was investigated. In this example, the EDI device 10A shown in Figure 5 was used to measure voltage [V], current [A], flow rate at inlet A of the desalination chamber 22 [L / h], flow rate at inlet B of the concentration chamber 24 (+ anode chamber 21) [L / h], flow rate ratio (A / B), and water quality (Din [μS / cm] and Dout [MΩ·cm]). The measurement results are shown in Table 2.

[0067] [Table 2]

[0068] Figure 9 plots the relationship between water quality and the flow rate ratio (A / B) of water flowing through the desalination chamber 22 and the concentration chamber 24 (+ anode chamber 21), based on the results in Table 2 above. When the flow rate ratio (A / B) decreases, the concentration ratio increases, and the ammonia concentration in the concentration chamber 24 increases. As a result, the amount of ammonia diffusing into the desalination chamber 22 increases, and the water quality of the desalination treated water deteriorates. As can be seen from the results in Figure 9, it was found that by setting the flow rate ratio (A / B) between 1 and 8, it is possible to produce pure water with a resistivity of 1 MΩ·cm or higher.

[0069] [Example 3] The relationship between the aforementioned "(4) Water flow SV (space velocity) in the desalination chamber" and the water quality of the desalination treated water was investigated. In this example, the EDI device 10A shown in Figure 5 was used to measure voltage [V], current [A], flow rate at inlet A of desalination chamber 22 [L / h], flow rate at inlet B of concentration chamber 24 (+ anode chamber 21) [L / h], water quality (Din [μS / cm] and Dout [MΩ·cm]), and water flow SV in desalination chamber 22. The measurement results are shown in Table 3.

[0070] [Table 3]

[0071] Figure 10 plots the relationship between water quality and the water flow rate (SV) of the desalination chamber 22 based on the results in Table 3 above. If the water flow rate (SV) of the desalination chamber 22 is set too low, the water quality deteriorates due to the influence of ammonia diffusing from the concentration chamber 24. Conversely, if the water flow rate (SV) of the desalination chamber 22 is set too high, ion capture and current regeneration failures occur in the ion exchange resin, resulting in a deterioration of water quality. As can be seen from the results in Figure 10, the water flow rate (SV) of the desalination chamber 22 should be set between 15 and 50 [h -1 It was found that by setting the value within the range of [ ], it is possible to produce pure water with a resistivity of 1 MΩ·cm or higher.

[0072] [Example 4] The relationship between the ammonium ion concentration in the treated water and the water quality of the desalination treatment water was investigated. In this example, the EDI device 10A shown in Figure 5 was used to measure voltage [V], current [A], flow rate at inlet A of desalination chamber 22 [L / h], flow rate at inlet B of concentration chamber 24 (+ anode chamber 21) [L / h], flow rate ratio (A / B), water quality (Din [μS / cm] and Dout [MΩ·cm]), and current value (I÷F) relative to the flow rate per desalination chamber. The measurement results are shown in Table 4.

[0073] [Table 4] Ammonium ions (NH4) in the treated water + It was found that by setting the concentration of ammonium ions (NH4) in the treated water to a range of 30-150 ppm, it is possible to produce pure water with a resistivity of 1 MΩ·cm or higher. Further investigation revealed that ammonium ions (NH4) in the treated water were found to be present in the treated water. + It was found that pure water with a resistivity of 1 MΩ·cm or higher can be produced if the concentration of ) is in the range of 5 to 150 ppm.

[0074] In the EDI devices 10, 10A to 10C described above, it is conceivable that the pH value of the water to be treated supplied to the desalination chamber 22 may fall outside the range of 9 to 12. In this case, a pH adjustment means may be provided in the piping for supplying the water to be treated to the desalination chamber 22 to adjust the pH of the water to be treated so that the pH value falls within the range of 9 to 12. For example, in the EDI device 10 shown in Figure 1, the pH adjustment means may be provided in the piping 61. The pH adjustment means may include, for example, a pH meter, an alkali addition device, and an acid addition device. The alkali addition device adds an alkaline agent such as calcium hydroxide or sodium hydroxide to the water to be treated. The acid addition device adds an acidic agent such as sulfuric acid or hydrochloric acid to the water to be treated. Based on the pH meter reading, the amount of alkaline agent or acidic agent added is adjusted so that the pH value falls within the range of 9 to 12. [Explanation of symbols]

[0075] 10. Electric deionized water production apparatus 11 Anode 12 Cathode 20 sections 21 Anode chamber 22 Desalination room 23 Cathode Chamber 24 Concentration chamber

Claims

1. An electrolytic deionized water production apparatus that processes water to be treated, which is ammonia-containing water with a pH value of 9 to 12, to produce pure water with a resistivity of 1 MΩ·cm or more, It has multiple compartments separated by a cation exchange membrane and an anion exchange membrane between the anode and the cathode. The plurality of compartments include at least one compartment which is filled with at least one desalting chamber, An electrolytic deionized water production apparatus characterized in that the water to be treated is supplied to the desalination chamber, a direct current is applied between the anode and the cathode, and when the water flow rate per chamber of the desalination chamber is F [L / h] and the current applied to the anode and the cathode is I [A], the value of (I ÷ F) is 0.05 to 0.8 [A・h / L].

2. It has an anode chamber equipped with the anode and a cathode chamber equipped with the cathode, The compartment comprises a concentration chamber filled with at least an anion exchanger, and the desalting chamber is provided adjacent to at least one side of the concentration chamber via the cation exchange membrane or the anion exchange membrane. A portion of the desalination water generated in the desalination chamber is branched off and supplied to the concentration chamber and at least one of the electrode chambers of the anode chamber and the cathode chamber. The electro-deionized water production apparatus according to claim 1, characterized in that when the total flow rate through the desalination chamber is A [L / h], and the total flow rate through the concentration chamber and the electrode chamber is B [L / h], the value of (A ÷ B) is 1 or more and 8 or less.

3. It has an anode chamber equipped with the anode and a cathode chamber equipped with the cathode, A portion of the desalination water generated in the desalination chamber is branched off and supplied to at least one of the electrode chambers of the anode chamber and the cathode chamber. The electrolytic deionized water production apparatus according to claim 1, characterized in that when the total flow rate through the desalination chamber is A [L / h] and the total flow rate through the electrode chamber is B [L / h], the value of (A ÷ B) is 1 or more and 8 or less.

4. An electrolytic deionized water production apparatus that processes water to be treated, which is ammonia-containing water with a pH value of 9 to 12, to produce pure water with a resistivity of 1 MΩ·cm or more, It has multiple compartments separated by a cation exchange membrane and an anion exchange membrane between an anode chamber equipped with an anode and a cathode chamber equipped with a cathode, The plurality of compartments include at least one compartment consisting of a concentration chamber filled with at least an anion exchanger and at least one desalting chamber adjacent to the concentration chamber via the cation exchange membrane or the anion exchange membrane and filled with at least a cation exchanger. The water to be treated is supplied to the desalination chamber, and a portion of the desalination treated water generated in the desalination chamber is branched off and supplied to the concentration chamber and at least one of the electrode chambers of the anode chamber and the cathode chamber. An electro-deionized water production apparatus characterized in that, when the total flow rate through the desalination chamber is A [L / h], and the total flow rate through the concentration chamber and the electrode chamber is B [L / h], the value of (A ÷ B) is 1 or more and 8 or less.

5. The flow velocity of the water to be treated per unit volume of the desalination chamber is 15 to 50 [h -1 An electrodeionized water production apparatus according to any one of claims 1 to 4.

6. The electro-deionized water production apparatus according to any one of claims 2 to 4, wherein the flow direction of the water to be treated in the desalination chamber and the flow direction of the desalination treatment water in the concentration chamber are in the counterflow direction.

7. The electrolytic deionized water production apparatus according to any one of claims 1 to 4, wherein the desalination chamber comprises an intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane, and is divided by the intermediate ion exchange membrane into a first small desalination chamber located closer to the anode and a second small desalination chamber located closer to the cathode, the first small desalination chamber is filled with at least an anion exchanger, the second small desalination chamber is filled with at least a cation exchanger, and the first small desalination chamber and the second small desalination chamber are in communication such that the water to be treated is supplied to one of the small desalination chambers and the water flowing out of the first small desalination chamber flows into the other small desalination chamber.

8. The electrolytic deionized water production apparatus according to any one of claims 1 to 4, wherein the concentration of ammonium ions in the water to be treated is 5 to 150 ppm.

9. The electrolytic deionized water production apparatus according to any one of claims 1 to 4, wherein the conductivity of the water to be treated is 40 to 300 μS / cm.

10. A water treatment method for producing pure water with a resistivity of 1 MΩ·cm or more by treating water to be treated, which is ammonia-containing water with a pH of 9 to 12, using an electrolytic deionized water production apparatus having a plurality of compartments separated between an anode and a cathode by a cation exchange membrane and an anion exchange membrane, wherein the plurality of compartments include at least one compartment section having at least one desalination chamber filled with a cation exchanger, and the apparatus has a plurality of compartments separated by a cation exchange membrane and an anion exchange membrane, wherein the plurality of compartments include at least one compartment section having at least one desalination chamber filled with at least one cation exchanger, A water treatment method comprising supplying the water to be treated to the desalination chamber while applying a direct current between the anode and the cathode, operating the electrolytic deionized water production apparatus such that the value of (I ÷ F) is 0.05 to 0.8 [A・h / L] when the flow rate of water per chamber of the desalination chamber is F [L / h] and the current applied to the anode and the cathode is I [A].

11. A water treatment method for producing pure water with a resistivity of 1 MΩ·cm or more by using an electrolytic deionized water production apparatus which has a plurality of compartments separated by a cation exchange membrane and an anion exchange membrane between an anode chamber equipped with an anode and a cathode chamber equipped with a cathode, wherein the plurality of compartments include at least one compartment consisting of a concentration chamber filled with at least an anion exchanger and at least one desalination chamber adjacent to the concentration chamber via the cation exchange membrane or the anion exchange membrane and filled with at least a cation exchanger, and by treating water to be treated which is ammonia-containing water with a pH of 9 to 12, the apparatus comprising: A water treatment method comprising supplying the water to be treated to the desalination chamber, branching off a portion of the desalination treated water generated in the desalination chamber and supplying it to the concentration chamber and at least one of the electrode chambers of the anode chamber and the cathode chamber, and operating the electro-deionized water production apparatus such that the value of (A ÷ B) is between 1 and 8, where A [L / h] is the total flow rate through the desalination chamber and B [L / h] is the total flow rate through the concentration chamber and the electrode chamber.

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