Electrodeionization device and operation method thereof

Abstract

An electrodeionization device (1) is provided with sub-blocks (3A-3F) in parallel between frames (2) and (2), the sub-blocks (3A-3F) forming a plurality of pairs of desalination chambers and concentration chambers. Water supply ports (4A), (4B) for disposing a water supply line (4) through which the water (W1) to be treated is introduced are formed at both ends of the upper side of the subblocks (3A)-(3F). Concentrated water supply ports (6A, 6B) are formed at both ends of the lower side of the unit, said concentrated water supply ports (6A, 6B) being provided with a concentrated water supply line (6) through which concentrated water (W3) is introduced into the concentration chamber. Water to be treated (W1) can be supplied from the water supply ports (4A, 4B) via the water supply line (4) from the upper side of each desalination chamber, and discharged from the treated water outflow ports (5A, 5B) via the treated water outflow line (5) from the lower side of each desalination chamber. In addition, concentrated water (W3) can be supplied from the concentrated water supply ports (6A, 6B) via the concentrated water supply line (6) from the lower side of each concentration chamber, and concentrated drainage (W4) can be discharged from the concentrated drainage outflow ports (7A, 7B) via the concentrated drainage outflow line (7) from the upper side of each concentration chamber. This electrodeionization device makes it possible to efficiently produce high-quality treated water.

Description

Technical Field

[0001] The present invention relates to an electrodeionization device and an operating method thereof, and in particular to an electrodeionization device and an operating method thereof capable of efficiently producing high-quality treated water. Background Art

[0002] Generally, an electrodeionization device alternately arranges cation exchange membranes and anion exchange membranes between the cathode (negative electrode) and the anode (positive electrode), and these cation exchange membranes and anion exchange membranes are used to form a desalting chamber and a concentrating chamber, and the desalting chamber and the concentrating chamber are filled with ion exchange resins. As ion exchange membranes such as cation exchange membranes and anion exchange membranes, in addition to heterogeneous membranes formed by adding binders such as polystyrene to powdered ion exchange resins, homogeneous membranes formed by polymerization of styrene-divinylbenzene, etc., membranes formed by graft polymerization of monomers having various anion exchange functions or cation exchange functions are also used.

[0003] As the electrodeionization device, Patent Document 1 discloses a device having Figure 3 and Figure 4 The device of the structure shown.

[0004] exist Figure 3 In the embodiment, the electrodeionization device 21 is a device in which a plurality of anion exchange membranes 33 and cation exchange membranes 34 are alternately arranged between electrodes (anode 31, cathode 32) to alternately form concentration chambers 35 and desalination chambers 36. Ion exchangers (anion exchangers and cation exchangers) composed of ion exchange resins, ion exchange fibers, or graft exchangers are mixed or filled in multiple layers in the desalination chambers 36. In addition, the concentration chambers 35, the anode chambers 37, and the cathode chambers 38 are also filled with ion exchangers.

[0005] In the electrodeionization device 21, a water supply mechanism (not shown) for supplying treated water W1 to the desalination chamber 36 and taking out treated water W2 and a concentrated water supply mechanism (not shown) for supplying concentrated water W3 to the concentrating chamber 35 are provided. In the present embodiment, the concentrated water W3 is introduced into the concentrating chamber 35 from the side close to the outlet of the treated water W2 of the desalination chamber 36, and flows out from the side close to the inlet of the desalination chamber 36, that is, the concentrated water W3 is introduced into the concentrating chamber 35 from the direction opposite to the flow direction of the treated water W1 in the desalination chamber 36, and the concentrated waste water W4 is ejected. In addition, it is described that as the concentrated water W3, water having a lower silica or boron concentration than the feed water (treated water W1) is introduced into the concentrating chamber from the side close to the outlet of the deionized water of the desalination chamber, and is made to flow out from the side close to the raw water inlet of the desalination chamber.

[0006] In particular, as a preferred embodiment, it is described as follows Figure 4As shown, a part of the treated water W2 obtained from the desalination chamber 36 is used as concentrated water W3, thereby circulating concentrated wastewater W4 with a reduced ion concentration.

[0007] Such an electrodeionization device is used as a pure water production device in various industries, such as semiconductor chip manufacturing processes, thermal power plants or nuclear power plants, petrochemical plants, and pharmaceutical manufacturing processes.

[0008] In particular, the semiconductor market requires high-quality processed water, with a resistivity of 15MΩ·cm or higher and a high boron / silicon dioxide removal rate. In addition, in recent years, in addition to high-purity processed water, operating conditions that take power and water conservation into consideration have also been required.

[0009] In addition, as a general-purpose electrodeionization device for semiconductor manufacturing processes, IP-VNX-55EX-2 manufactured by Evoqua Water Technologies, LLC (558 Clark Road Tewksbury, Massachusetts 01876, USA) is commercially available. Figure 5 As shown, the electrodeionization device 40 includes sub-blocks 41 to 46 in a frame 50. Each of the sub-blocks 41 to 46 forms a plurality of desalting chamber and concentrating chamber pairs by alternately arranged cation exchange membranes CEM and anion exchange membranes AEM.

[0010] The sub-blocks 41 and 43 of the electrodeionization device 40 have 17 pairs of desalting chambers and concentrating chambers, and the sub-block 42 has 16 such pairs. The sub-blocks 44 and 46 have 17 such pairs, and the sub-block 45 has 16 such pairs. Figure 5 The "-" in the figure indicates the negative electrode chamber 47, and the "+" in the figure indicates the positive electrode chamber 48. Reference numeral 49 indicates a power supply box.

[0011] exist Figure 5 In the operation method of the electrodeionization device 40 shown, the supply water (treated water) W1 and the concentrated water W3 are supplied from each port to the sub-blocks 41 to 43. A part of the supply water W1 passes through the water supply path (upper head) of the sub-blocks 41 to 43 and is supplied to the water supply path (upper head) of the sub-blocks 44 to 46. The supply water passes through each desalination chamber of each sub-block 41 to 46, and is taken out from the treated water extraction port as treated water W2 via the desalted water collection path (lower head).

[0012] The concentrated water is supplied to the heads (upper heads) of the sub-blocks 41 to 43, and is introduced from the concentrated water collection paths (lower heads) of the sub-blocks 41 to 43 to the concentrated water heads (lower heads) of the sub-blocks 44 to 46 through the respective concentrating chambers of the sub-blocks 41 to 43, and is passed into the respective concentrating chambers of the sub-blocks 44 to 46, and is taken out as concentrated waste water W4 from the concentrated waste water taking-out ports through the upper heads of the concentrating chambers of the sub-blocks 44 to 46. That is, in Figure 5 In the electrodeionization device 40 shown, the supply water W1 is passed to all the desalination chambers in a downward flow. On the other hand, the flow direction of the concentrated water W3 is downward flow in the first half (sub-blocks 41, 42, 43) and upward flow in the second half (sub-blocks 44, 45, 46). In this way, by making the flow directions of the concentrated water W3 in the sub-blocks 41 to 43 and the sub-blocks 44 to 46 opposite, the amount of water used in the concentrated wastewater W4 is reduced by half.

[0013] Prior art literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent Application Publication No. 2002-205069. Summary of the invention

[0016] Problems to be solved by the invention

[0017] However, in the electrodeionization device 21 described in Patent Document 1, diffusion (reverse diffusion) from the concentration chamber 35 to the desalination chamber 36 caused by the concentration difference between the ion components of the treated water W2 and the concentrated wastewater W4 at the outlet side of the desalination chamber 36 can be prevented, thereby reducing the silica and boron concentrations of the treated water W2. However, since the water flow rate of the desalination chamber 36 is increased in accordance with the water flow to the concentration chamber 35, the amount of ions to be treated increases compared to the usual water flow method, thereby increasing the load on the electrodeionization device 21. Therefore, when the boron concentration of the supply water (treated water) W1 is low and can be fully treated by the electrodeionization device 21, there is no problem. However, when the boron concentration of the supply water W1 increases, it cannot be fully treated, and there is a problem that the boron concentration of the treated water W2 may increase.

[0018] In addition, according to Figure 5 In the water passing method of the electrodeionization device shown, in sub-blocks 41 to 43, the difference in ion concentration between the lower part of the desalting chamber and the lower part of the concentrating chamber becomes large, so that ions move from the concentrating chamber to the desalting chamber due to concentration diffusion, resulting in a problem of deterioration in the quality of treated water.

[0019] Therefore, considering Figure 5 The electrodeionization device shown in the patent document 1 adopts the water passing method described in the patent document 1, but Figure 5In the electrodeionization device shown in the figure, the desalting chamber and the concentrating chamber flow in parallel in the unit on the left side, and the desalting chamber and the concentrating chamber flow in countercurrent in the unit on the right side, which is difficult to use.

[0020] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrodeionization apparatus and an operating method thereof that can efficiently produce high-quality treated water.

[0021] Means for solving problems

[0022] In order to achieve the above-mentioned purpose, first, the present invention provides an electrodeionization device, which comprises a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes arranged between the cathode and the anode, and a plurality of desalination chambers and concentration chambers separated by these cation exchange membranes and anion exchange membranes, wherein the desalination chambers and the concentration chambers are filled with ion exchange resins, and the electrodeionization device has a mechanism for introducing treated water into the plurality of desalination chambers and taking out deionized water, and a concentrated water introduction mechanism for introducing concentrated water into the concentration chambers, wherein on one side of each of the desalination chambers, a treated water inflow branch pipe branched in sequence from a treated water supply line is connected, and on the other side of each of the desalination chambers, a branch pipe for treating water is connected. Outflow pipes for treated water are respectively connected, and these outflow pipes for treated water are merged into an outflow line for treated water. Both sides of the supply line for treated water are open so that the treated water can be supplied from both sides of the supply line for treated water. On the other side of each concentration chamber, branch pipes for concentrated water branched in sequence from the supply line for concentrated water are respectively connected. Moreover, on one side of each concentration chamber, outflow pipes for concentrated water are respectively connected, and these outflow pipes for concentrated water are merged into an outflow line for concentrated water. Both sides of the supply line for concentrated water are open so that the concentrated water can be supplied from both sides of the supply line. The electrodeionization device is formed so that the same water as the treated water can be supplied as the concentrated water (Invention 1).

[0023] According to the above invention (Invention 1), treated water as the water supply of the desalination chamber is introduced as concentrated water of the electrodeionization device, so that the water flow rate of the desalination chamber can be reduced compared with the case where treated water (desalted water) is used as concentrated water, and thus the water quality does not decrease as the amount of treated water increases. Furthermore, concentrated water can be supplied from both sides of the supply line formed on the left and right sides of the unit, so that by passing water to all the concentration chambers in the direction opposite to the water flow direction of the treated water of the desalination chamber, diffusion caused by the concentration difference between the desalted water and the concentrated water near the outlet of the desalination chamber can be prevented, thereby improving the water quality of the treated water. The combined action of these effects can be used to optimize the water quality of the electrodeionization device.

[0024] In the above invention (Invention 1), it is preferred that the treated water flow rate of the electrodeionization device is 5 to 15 m3 / h(Invention 2).

[0025] According to the above invention (Invention 2), in the electrodeionization device, the amount of treated water does not increase compared to the case where the treated water (desalted water) in the desalination chamber is used for concentrated water, and therefore the water quality does not deteriorate accordingly. 3 In a small-scale electrodeionization device with a flow rate of less than / h, the influence of concentrated water on the water to be treated will become greater, so it can be particularly preferably applied.

[0026] In addition, secondly, the present invention provides an operation method of an electrodeionization device, the electrodeionization device comprises a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes arranged between the cathode and the anode, and a plurality of desalination chambers and concentration chambers separated by the cation exchange membranes and anion exchange membranes, the desalination chambers and the concentration chambers are filled with ion exchange resins, the electrodeionization device has a mechanism for introducing treated water into the plurality of desalination chambers and taking out deionized water, and a concentrated water introduction mechanism for introducing concentrated water into the concentration chambers, one side of each of the desalination chambers is connected to a treated water inflow branch pipe that branches off in sequence from a treated water supply line, and on the other side of each of the desalination chambers, a treated water inflow branch pipe is connected to the treated water supply line. The treated water is respectively connected to an outflow pipe of the treated water, and these outflow pipes of the treated water are merged into an outflow line of the treated water, the two sides of the supply line of the treated water are open, and the other side of each concentration chamber is respectively connected to an inflow branch pipe of concentrated water branched in sequence from the supply line of concentrated water, and the one side of each concentration chamber is respectively connected to an outflow pipe of concentrated wastewater, and these outflow pipes of concentrated wastewater are merged into an outflow line of concentrated wastewater, and the two sides of the concentrated water supply line are open, wherein the treated water is supplied from both sides of the supply line, the treated water is taken out from the outflow line, the water same as the treated water is supplied from both sides of the concentrated water supply line, and the concentrated wastewater is discharged from the outflow line of the concentrated wastewater (Invention 3).

[0027] According to the above invention (Invention 3), the treated water as the water supply of the desalination chamber is introduced as the concentrated water of the electrodeionization device, so that the water flow rate of the desalination chamber can be reduced compared with the case where the treated water (desalted water) is used as the concentrated water, and therefore, the water quality does not decrease as the amount of treated water increases. Furthermore, by supplying the concentrated water from both sides of the supply line formed on the left and right sides of the unit, the water is passed to all the concentrating chambers in the direction opposite to the water flow direction of the treated water of the desalination chamber, so that the diffusion caused by the concentration difference between the desalted water and the concentrated water near the outlet of the desalination chamber can be prevented, thereby improving the water quality of the treated water. The combined action of these effects can be used to optimize the water quality of the electrodeionization device.

[0028] In the above invention (Invention 3), it is preferred that the treated water flow rate of the electrodeionization device is 5 to 15 m 3 / h(Invention 4).

[0029] According to the above invention (Invention 4), in the electrodeionization device, the amount of treated water does not increase compared to the case where the treated water (desalted water) in the desalination chamber is used for concentrated water, and therefore the water quality does not deteriorate accordingly. 3 / h or less, the concentrated water has a greater impact on the water to be treated, so it can be particularly preferably used.

[0030] In the above invention (Invention 4), it is preferred that the boron concentration of the water supply to be treated is 0.1 μg / L or more (Invention 5).

[0031] According to the above invention (Invention 5), for treated water of this water quality, if the amount of treated water in the desalination chamber is increased, it is easy to cause a deterioration in water quality. However, by using the same water as the treated water as concentrated water and supplying the concentrated water from both sides of the supply line formed on the left and right sides of the unit, there is no need to increase the amount of treated water in the desalination chamber compared to the case where the treated water in the desalination chamber is used as concentrated water, thereby improving the water quality of the treated water.

[0032] In the above invention (Invention 4), it is preferred that the conductivity of the water to be treated is 0.1 to 1 mS / m (Invention 6).

[0033] According to the above invention (Invention 6), by using the same water as the treated water as concentrated water and supplying the concentrated water from both sides of the supply lines formed on the left and right sides of the unit, water is passed to all the concentration chambers in a direction opposite to the direction of water flow in the desalination chambers, thereby preventing diffusion caused by the concentration difference between the desalination chamber and the concentration chamber generated near the outlet of the desalination chamber, thereby improving the water quality of the treated water.

[0034] In the above inventions (Inventions 3 to 5), it is preferred that the inorganic carbonic acid concentration of the water to be treated is 50 to 1000 μg / L in terms of carbon (C) (Invention 7).

[0035] According to the above invention (Invention 7), by using the same water as the treated water as concentrated water and supplying the concentrated water from both sides of the supply lines formed on the left and right sides of the unit, water is passed to all the concentration chambers in a direction opposite to the direction of water flow in the desalination chambers, thereby preventing diffusion caused by the concentration difference between the desalination chamber and the concentration chamber generated near the outlet of the desalination chamber, thereby improving the water quality of the treated water.

[0036] Effects of the Invention

[0037] The electric deionization device of the present invention makes the flow direction of the treated water in the desalination chamber opposite to the flow direction of the concentrated water to the concentration chamber. Furthermore, the two sides of the supply line of the concentrated water are open, and the concentrated water can be supplied from both sides of the supply line. The treated water can be supplied as concentrated water. Therefore, by passing the same water as the treated water as the water supply of the desalination chamber as concentrated water, the water flow rate of the desalination chamber can be reduced compared with the case where the treated water (desalted water) is used for concentrated water. Therefore, the water quality will not decrease as the amount of treated water increases. Moreover, the concentrated water can be supplied from both sides of the supply line formed on the left and right sides of the unit. Therefore, by passing the concentrated water to all the concentration chambers in the direction opposite to the water flow direction of the treated water in the desalination chamber, the diffusion caused by the concentration difference between the desalted water and the concentrated water near the outlet of the desalination chamber can be prevented, thereby improving the water quality of the treated water. The combined action of these effects can be used to optimize the water quality of the electric deionization device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram showing the structure of the electrodeionization apparatus according to the first embodiment of the present invention.

[0039] Figure 2 It is a schematic diagram showing the structure of an electrodeionization apparatus according to a second embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram showing the structure of a conventional electrodeionization device (Patent Document 1).

[0041] Figure 4 This is a schematic diagram showing the flow of water in the desalting compartment and the concentrating compartment of a conventional electrodeionization device (Patent Document 1).

[0042] Figure 5 This is a schematic diagram showing the structure of a conventional (commercially available) electrodeionization device. DETAILED DESCRIPTION

[0043] Hereinafter, the electrodeionization apparatus of the present invention and the operating method using the electrodeionization apparatus will be described with reference to the drawings.

[0044] [First embodiment]

[0045] [Electrodeionization device]

[0046] Figure 1 FIG. 2 shows an electrodeionization device according to a first embodiment of the present invention. Figure 1In the electrodeionization device 1, sub-blocks 3A to 3F are arranged in parallel between frames 2, 2. Each sub-block 3A to 3F is formed with a plurality of desalination chambers (not shown) and concentration chambers (not shown) using cation exchange membranes CEM and anion exchange membranes AEM that are alternately arranged. Ion exchange resins (for example, mixed resins of anion exchange resins and cation exchange resins) are filled in these desalination chambers and concentration chambers.

[0047] At both ends of one side (upper side in the figure) of the unit in which these sub-blocks 3A to 3F are connected, water supply ports 4A and 4B of a water supply line 4 for introducing treated water W1 into the desalination chamber are formed, and on the other hand, at both ends of the other side (lower side in the figure) of the unit, treated water outflow ports 5A and 5B of a treated water outflow line 5 for discharging treated water W2 as deionized water after treatment in the desalination chamber are formed. The water supply line 4 branches in the sub-blocks 3A to 3F, and is connected to the upper side of each desalination chamber as a treated water inflow branch pipe, and is connected to a treated water outflow pipe at the lower side of each desalination chamber, and these treated water outflow pipes merge into the treated water outflow line 5. Thus, the treated water W1 can be supplied from the upper side of each desalination chamber via the water supply line 4 from the water supply ports 4A and 4B, and further discharged from the lower side of each desalination chamber via the treated water outflow line 5 from the treated water outflow ports 5A and 5B.

[0048] In addition, concentrated water supply ports 6A and 6B of a concentrated water supply line 6 for supplying concentrated water W3 as concentrated water to the concentrating chamber are formed at both ends of the lower side of the unit in which the sub-blocks 3A to 3F are connected, and concentrated waste water outflow ports 7A and 7B of a concentrated waste water outflow line 7 for discharging concentrated waste water W4 are formed at both ends of the upper side of the unit in the figure. The concentrated water supply line 6 branches in the sub-blocks 3A to 3F and is connected to the lower side of each concentrating chamber as a concentrated water inflow branch pipe, and a concentrated waste water outflow pipe is connected to the upper side of each concentrating chamber, and these concentrated waste water outflow pipes merge into the concentrated waste water outflow line 7. Thus, the concentrated water W3 can be supplied from the lower side of each concentrating chamber from the concentrated water supply ports 6A and 6B via the concentrated water supply line 6, and the concentrated waste water W4 can be discharged from the upper side of each concentrating chamber from the concentrated waste water outflow ports 7A and 7B via the concentrated waste water outflow line 7.

[0049] for Figure 1 In the illustrated electrodeionization device 1, sub-blocks 3A, 3C, 3D, and 3F have a plurality of (e.g., 17) pairs of desalination chambers and concentrating chambers, and sub-blocks 3B and 3E have one less (e.g., 16) pair of desalination chambers and concentrating chambers. Figure 1A cathode chamber (cathode) 8 is disposed at the left and right ends between the frames 2 and 2, and a pair of anode chambers (anode) 9 is disposed in the center, forming a structure of two blocks of sub-blocks 3A, 3B, 3C and sub-blocks 3D, 3E, 3F. In addition, reference numeral 10 is a power supply box.

[0050] In the electrodeionization device 1 of the present embodiment, the same water as the treated water W1 is used as the concentrated water W3. The flow rate (desalination chamber flow rate) of the treated water W2 by the sub-blocks 3A to 3F is preferably 5 to 15 m / s. 3 / h. The flow rate of treated water W2 (desalting chamber flow rate) is less than 5m 3 / h, the amount of water treated is too small and not practical. On the other hand, if it is greater than 15m 3 / h, since the flow rate of the treated water W2 is large, the advantages compared with the case of using the treated water W2 as concentrated water W3 cannot be fully obtained. Furthermore, the flow rate of the concentrated wastewater W4 relative to the water supply flow rate (the flow rate of the treated water W2 + the flow rate of the concentrated wastewater W4) is preferably 2.5 to 10 volume%, and particularly preferably about 5 volume%. When the flow rate of the concentrated wastewater W4 is less than 2.5 volume%, since the concentrated wastewater W4 is too small, the ion concentration flowing into the desalination chamber becomes high, and the reverse diffusion cannot be ignored, which easily causes the water quality of the treated water W2 to deteriorate. On the other hand, when it is greater than 10 volume%, the concentrated water W3 becomes more, and the amount of water supplied by using the treated water W1 as concentrated water W3 is too much, so it is not preferred.

[0051] [Operation method of electrodeionization device]

[0052] Next, a method for operating the electrodeionization apparatus using the electrodeionization apparatus 1 having the above-described configuration will be described.

[0053] First, treated water W1 is supplied from the water supply ports 4A and 4B to the desalination chambers of the sub-blocks 3A to 3F from the upper side via the water supply line 4, and concentrated water W3 is supplied from the concentrated water supply ports 6A and 6B to each concentration chamber from the lower side via the concentrated water supply line 6. Treated water W1 is passed through the desalination chambers of each sub-block 3A to 3F from the upper side to the lower side in the figure, and is discharged from each treated water outflow pipe through the treated water outflow line 5 from the treated water outflow ports 5A and 5B. In addition, concentrated water W3 is passed through the concentration chambers of each sub-block 3A to 3F from the lower side to the upper side in the figure, and is discharged from each concentrated wastewater outflow pipe through the concentrated wastewater outflow line 7 from the concentrated wastewater outflow ports 7A and 7B. In this way, by supplying treated water W1 and concentrated water W3 from both sides of the unit, the water volume and water pressure of the water supply of the sub-blocks 3A to 3F can be homogenized, and the water quality of treated water W2 can be stabilized.

[0054] The water flow SV (space velocity) of the desalting chamber is preferably 70 to 150 / h, and particularly preferably 100 to 120 / h. The water flow SV (space velocity) of the concentrating chamber is preferably 5 to 50 / h, and particularly preferably 10 to 25 / h. The recovery rate is preferably 80 to 99%, and particularly preferably 90 to 95%. The current applied is preferably 0.15 to 2.30 A / (m 3 / h), particularly preferably 0.7A / (m 3 / h)~1.2A / (m 3 / h).

[0055] In this embodiment, the treated water W1 is passed through all the desalination chambers in a downward flow, while the concentrated water W3 is passed through all the concentration chambers in an upward flow. The same water as the treated water W1 is supplied as the concentrated water W3.

[0056] The conductivity of the treated water W1 (supply water) is preferably 0.1 to 1 mS / m, and particularly preferably 0.1 to 0.5 mS / m. When the conductivity of the treated water W1 (supply water) is greater than 1 mS / m, reverse diffusion from the concentration chamber to the desalination chamber is likely to occur, which is likely to cause a decrease in the water quality of the treated water W2, and is therefore not preferred.

[0057] In addition, the present embodiment can be suitably applied to the case where the treated water W1 (water supply) has a boron concentration of 0.1 μg / L or more. When the treated water W1 with a boron concentration of 0.1 μg / L or more is supplied to the desalination chamber, if the amount of treated water increases, it is easy to cause a decrease in water quality. However, by supplying the same water as the treated water W1 as concentrated water W3 as in the present embodiment, it is not necessary to increase the amount of treated water in the desalination chamber compared to the case where the treated water W2 in the desalination chamber is used as concentrated water W3, and therefore, the water quality of the treated water can be improved. In addition, in order to keep the boron concentration of the treated water W1 (water supply) less than 0.1 μg / L, it is necessary to use a certain degree of water treatment equipment for treatment. Therefore, it is not realistic.

[0058] Furthermore, the inorganic carbonate concentration of the treated water W1 (feed water) is preferably 50 to 1000 μg / L in terms of carbon (C). When the inorganic carbonate concentration of the treated water W1 (feed water) is greater than 1000 μg / L in terms of carbon (C), the carbonate concentration is too high, and reverse diffusion from the concentration chamber to the desalination chamber is likely to occur, which not only easily causes a decrease in the water quality of the treated water W2, but also carbonates such as calcium carbonate are likely to precipitate on electrodes, etc.

[0059] As the treated water W1 (supply water) as described above, it is suitable to use water that has been pre-treated as needed for industrial water, city water, well water, etc., and then treated by a water treatment device including a reverse osmosis membrane device. It is preferred to appropriately detect the conductivity, boron concentration, and inorganic carbonic acid concentration of the treated water of the reverse osmosis membrane device and confirm that they are within the above ranges before use.

[0060] [Second Embodiment]

[0061] [Electrodeionization device]

[0062] Figure 2 FIG. 2 shows an electrodeionization device according to a second embodiment of the present invention. The electrodeionization device of this embodiment has substantially the same structure as the first embodiment described above, and therefore, the same reference numerals are given to the same structures, and detailed descriptions thereof are omitted. Figure 2 In the electrodeionization device 1, sub-blocks 3A to 3G are arranged in parallel between frames 2, 2. Each sub-block 3A to 3G is formed with a plurality of pairs of desalination chambers (not shown) and concentration chambers (not shown) by alternately arranged cation exchange membranes CEM and anion exchange membranes AEM. These desalination chambers and concentration chambers are filled with ion exchange resins (for example, mixed resins of anion exchange resins and cation exchange resins).

[0063] At both ends of one side (upper side in the figure) of the unit in which these sub-blocks 3A to 3G are connected, water supply ports 4A and 4B of a water supply line 4 for introducing treated water W1 into the desalination chamber are formed, and on the other hand, at both ends of the other side (lower side in the figure) of the unit, treated water outflow ports 5A and 5B of a treated water outflow line 5 for discharging treated water W2 as deionized water after treatment in the desalination chamber are formed. The water supply line 4 branches in the sub-blocks 3A to 3G, and is connected to the upper side of each desalination chamber as a treated water inflow branch pipe, and a treated water outflow pipe is connected to the lower side of each desalination chamber, and these treated water outflow pipes are merged into the treated water outflow line 5. Thus, the treated water W1 can be supplied from the upper side of each desalination chamber via the water supply line 4 from the water supply ports 4A and 4B, and further discharged from the lower side of each desalination chamber via the treated water outflow line 5 from the treated water outflow ports 5A and 5B.

[0064] In addition, concentrated water supply ports 6A and 6B of a concentrated water supply line 6 for supplying concentrated water W3 as concentrated water to the concentrating chamber are formed at both ends of the lower side of the unit in which the sub-blocks 3A to 3G are connected, and concentrated waste water outflow ports 7A and 7B of a concentrated waste water outflow line 7 for discharging concentrated waste water W4 are formed at both ends of the upper side of the unit in the figure. The concentrated water supply line 6 branches in the sub-blocks 3A to 3G and is connected to the lower side of each concentrating chamber as a concentrated water inflow branch pipe, and a concentrated waste water outflow pipe is connected to the upper side of each concentrating chamber, and these concentrated waste water outflow pipes merge into the concentrated waste water outflow line 7. Thus, the concentrated water W3 can be supplied from the lower side of each concentrating chamber from the concentrated water supply ports 6A and 6B via the concentrated water supply line 6, and further discharged from the upper side c of each concentrating chamber from the concentrated waste water outflow ports 7A and 7B via the concentrated waste water outflow line 7.

[0065] Furthermore, in this embodiment, a cathode chamber (cathode) 8 is disposed on the left end side of the frame 2, 2, and an anode chamber (anode) 9 is disposed on the right end side, forming a block structure of the sub-blocks 3A to 3G, and a sealing plate 11 is disposed in the middle of the concentrated wastewater outflow line 7, thereby dividing the water flow of the concentrated wastewater outflow line 7 at the concentrated wastewater outflow ports 7A and 7B. In addition, reference numeral 10 is a power supply box.

[0066] In the electrodeionization device 1 of the present embodiment as described above, the same water as the treated water W1 is used as the concentrated water W3. In addition, the flow rate (desalination chamber flow rate) of the treated water W2 by the sub-blocks 3A to 3G is preferably 5 to 20 m 3 / h. The flow rate of treated water W2 (desalting chamber flow rate) is less than 5m 3 / h, the amount of water treated is too small and not practical. On the other hand, if it is greater than 20m 3 / h, the flow rate of the treated water W2 is large, and therefore, the advantages compared with the case of using the treated water W2 as concentrated water W3 cannot be fully obtained. Furthermore, the flow rate of the concentrated wastewater W4 relative to the water supply flow rate (the flow rate of the treated water W2 + the flow rate of the concentrated wastewater W4) is preferably 2.5 to 10 volume%, and particularly preferably about 5 volume%. When the flow rate of the concentrated wastewater W4 is less than 2.5 volume%, since the concentrated wastewater W4 is too small, the ion concentration flowing into the desalination chamber becomes high, and the reverse diffusion cannot be ignored, which easily causes the water quality of the treated water W2 to deteriorate. On the other hand, when it is greater than 10 volume%, the concentrated water W3 becomes more, and the amount of water supplied is too much when the treated water W1 is used as concentrated water W3, which is not preferred.

[0067] By setting a block structure in which the negative electrode 8 is provided on the left end side and the anode 9 is provided on the right end side as in the present embodiment, the number of anode chambers and cathode chambers between the frames 2, 2 can be reduced compared to the case in which a pair of anode chambers (anodes) 9 are arranged in the center as in the first embodiment, so that the number of sub-blocks 3A... can be increased, and thus the flow rate (desalting chamber flow rate) of the treated water W2 can be increased compared to the first embodiment. On the other hand, since the distance between the negative electrode chamber (negative electrode) 8 and the anode chamber (anode) 9 becomes longer, it is necessary to apply a higher voltage than in the first embodiment, especially a voltage of about 2 times or more, and the current amount also becomes larger, and the power supply conditions are different, but the operation method other than this can be substantially the same as the first embodiment described above.

[0068] The electrodeionization device and the operation method thereof of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments and can be implemented in various modifications. Figure 1 Six sub-blocks are set in Figure 2 7 sub-blocks are provided, but it is not limited thereto, and it can be 1 to 12. In addition, the number of pairs of desalination chambers and concentration chambers in one sub-block can be 1 to 100. Furthermore, in this embodiment, the treated water W2 or the concentrated wastewater W4 is taken out from both sides of the unit, but it can also be taken out from any side.

[0069] Example

[0070] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0071] [Example 1]

[0072] As the electrodeionization device, IP-VNX55EX-2 manufactured by Evoqua Water Technologies, LLC was used. Figure 1 Treated water was obtained by the water supply and concentrated wastewater passing method shown in the figure. The resistivity and boron concentration of the treated water were measured. The results are shown in Table 1.

[0073] In addition, in Example 1, other conditions are as follows.

[0074] Membrane area: 0.06m 2 .

[0075] Desalination chamber thickness: 9mm.

[0076] Concentration chamber thickness: 4mm.

[0077] Desalination chamber flow: 10.3m 3 / h.

[0078] Concentrated water: The same water as the desalination chamber supply water is introduced.

[0079] Concentration chamber flow rate: 0.50m 3 / h.

[0080] Recovery rate: 95.4%.

[0081] Operating current value: 10A.

[0082] Current density: 0.86A / (m 3 / h).

[0083] Boron concentration in water supply: 1-3 μg / L.

[0084] Water supply conductivity: 0.1~0.2mS / m.

[0085] Inorganic carbon concentration in water supply: The concentration in terms of C is 130-160 μg / L.

[0086] [Comparative Example 1]

[0087] In Example 1, treated water in the desalination chamber was passed as concentrated water to obtain treated water. The resistivity and boron concentration of the treated water were measured. The results are shown in Table 1.

[0088] In addition, in Comparative Example 1, other conditions were as follows.

[0089] Membrane area: 0.06m 2 .

[0090] Desalination chamber thickness: 9mm.

[0091] Concentration chamber thickness: 4mm.

[0092] Desalination chamber flow: 11.6m 3 / h.

[0093] Concentrated water: The treated water that enters the desalination chamber.

[0094] Concentration chamber flow rate: 0.56m 3 / h.

[0095] Recovery rate: 95.1%.

[0096] Operating current value: 10A.

[0097] Current density: 0.86A / (m 3 / h).

[0098] Boron concentration in water supply: 1-3 μg / L.

[0099] Water supply conductivity: 0.1~0.2mS / m.

[0100] Inorganic carbon concentration in water supply: The concentration in terms of C is 130-160 μg / L.

[0101] Table 1

[0102] Example 1 Comparative Example 1 Boron concentration in treated water [ug / L] 0.03 0.05 Resistivity of treated water [MΩ·cm] 18.1 18.1

[0103] According to Table 1, the resistivity of the treated water of Example 1 and Comparative Example 1 is the same value, but the boron concentration of the treated water of Example 1 is a lower value. According to this result, when the water quality of the supply water is within a specific range, the method of Example 1 in which water the same as the supply water is passed into the concentration chamber and the treated water in the desalination chamber is countercurrently circulated is more effective for removing boron than the method of Comparative Example 1 in which the desalted water (treated water) is passed into the concentration chamber in a countercurrent manner. Here, as conditions for the method of countercurrent supply of the water to be effective, it is considered that the boron concentration is above a specified value (a concentration that cannot be fully treated by the method of countercurrent supply of the treated water) and the ion concentration of the supply water is within a specified range (when the ion concentration of the supply water becomes higher, the influence of the concentration diffusion in the lower part of the desalination chamber increases). In particular, it is speculated that when the flow rate in the desalination chamber is 15m 3 It is effective in small electrodeionization devices with a flow rate of less than 1000 rpm.

[0104] [Example 2]

[0105] As the electrodeionization device, IP-LXM4X-4 manufactured by Evoqua Water Technologies, LLC was used. Figure 1 Treated water was obtained by the water supply and concentrated wastewater passing method shown in the figure. The resistivity and boron concentration of the treated water were measured. The results are shown in Table 2.

[0106] In addition, in Example Comparative Example 2, other conditions were as follows.

[0107] Desalination chamber flow rate: 4.7L / min.

[0108] Concentrated water: The same water as the desalination chamber supply water is introduced.

[0109] Concentration chamber flow rate: 1.0L / min.

[0110] Recovery rate: 82%.

[0111] Boron concentration in water supply: 1 μg / L.

[0112] Water supply conductivity: 1.2~1.4mS / m.

[0113] Inorganic carbon concentration in water supply: 6 mg / L in terms of C.

[0114] [Example 3]

[0115] In Example 2, the same procedure was followed except that the flow rate in the desalination chamber was increased to obtain treated water. The resistivity and boron concentration of the treated water were measured. The results are shown in Table 2.

[0116] In addition, in Comparative Example 3, other conditions were as follows.

[0117] Desalination chamber flow rate: 5.7L / min.

[0118] Concentrated water: The same water as the desalination chamber supply water is introduced.

[0119] Concentration chamber flow rate: 1.0L / min.

[0120] Recovery rate: 82%.

[0121] Boron concentration in water supply: 1 μg / L.

[0122] Water supply conductivity: 1.2~1.4mS / m.

[0123] Inorganic carbon concentration in water supply: 6 mg / L in terms of C.

[0124] Table 2

[0125] Example 2 Example 3 Boron concentration in treated water [ug / L] 0.03 0.08 Resistivity of treated water [MΩ·cm] 17.2 17.7

[0126] As can be seen from Table 2, under the water supply conditions of this experimental example, Example 2 has a lower boron concentration and a lower resistivity. It is inferred that the reduction of the flow rate in the desalination chamber is effective in improving the boron removal performance. In addition, it is shown that when water with a high ion concentration (especially inorganic carbon) is used as concentrated water for countercurrent flow with the desalination chamber, diffusion caused by the concentration difference in the lower part of the desalination chamber occurs, and the resistivity of the treated water is reduced.

[0127] Description of Reference Numerals

[0128] 1: Electrodeionization device.

[0129] 2: Framework.

[0130] 3A~3F: sub-block.

[0131] 4: Water supply line.

[0132] 4A, 4B: Water supply ports.

[0133] 5: Treat the water outflow line.

[0134] 5A, 5B: Process water outflow ports.

[0135] 6: Concentrated water supply line.

[0136] 6A, 6B: Concentrated water supply ports.

[0137] 7: Concentrated drainage outflow line.

[0138] 7A: Concentrate drain outflow port.

[0139] 8: Negative electrode chamber.

[0140] 9: Anode chamber.

[0141] 10: Power box.

[0142] 11: Closed plate.

[0143] W1: water to be treated (supply water). W2: treated water.

[0144] W3: Concentrated water.

[0145] W4: Concentrated drainage.

Claims

1. An electrodeionization device, comprising a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes disposed between the cathode and the anode, and a plurality of desalination chambers and concentrating chambers separated by the cation exchange membranes and anion exchange membranes, wherein the desalination chambers and the concentrating chambers are filled with ion exchange resins, the electrodeionization device having a mechanism for passing treated water into the plurality of desalination chambers and taking out deionized water, and a concentrated water introduction mechanism for passing concentrated water into the concentrating chambers, wherein: One side of each desalination chamber is connected to a treated water inflow branch pipe that branches off in sequence from a treated water supply line, and the other side of each desalination chamber is connected to a treated water outflow pipe, and these treated water outflow pipes are merged into the treated water outflow line. Both sides of the treated water supply line are open, so that the treated water can be supplied from both sides of the treated water supply line. The other side of each of the concentration chambers is connected to a concentrated water inflow branch pipe that is sequentially branched from the concentrated water supply line, and the one side of each of the concentration chambers is connected to an outflow pipe of concentrated waste water, and these outflow pipes of concentrated waste water are merged into the outflow line of concentrated waste water. Both sides of the concentrated water supply line are open so that the concentrated water can be supplied from both sides of the supply line. The electrodeionization device is formed so as to be able to supply the same water as the water to be treated as the concentrated water.

2. The electrodeionization device according to claim 1, wherein: The treated water flow rate of the electrodeionization device is 5 to 15 m 3 / h.

3. An operating method of an electrodeionization device, the electrodeionization device comprising a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes disposed between the cathode and the anode, and a plurality of desalination chambers and concentrating chambers separated by the cation exchange membranes and anion exchange membranes, wherein the desalination chambers and the concentrating chambers are filled with ion exchange resins, the electrodeionization device having a mechanism for introducing treated water into the plurality of desalination chambers and taking out deionized water, and a concentrated water introduction mechanism for introducing concentrated water into the concentrating chambers, wherein one side of each of the desalination chambers is connected to a channel from the treated water to the concentrating chambers. The treated water branched from the water supply line flows into the branch pipe in sequence, and the outflow pipes of the treated water are connected to the other side of each desalination chamber, and these outflow pipes of the treated water are merged into the outflow line of the treated water. Both sides of the treated water supply line are open. The concentrated water branched from the concentrated water supply line is connected to the other side of each concentration chamber, and the outflow pipes of the concentrated wastewater are connected to one side of each concentration chamber, and these outflow pipes of the concentrated wastewater are merged into the outflow line of the concentrated wastewater. Both sides of the concentrated water supply line are open, wherein, The same water as the treated water is supplied from both sides of the supply line, and the treated water is taken out from the outflow line. The water to be treated is supplied from both sides of the concentrated water supply line, and the concentrated wastewater is discharged from the concentrated wastewater outflow line.

4. The method for operating the electrodeionization device according to claim 3, wherein: The treated water flow rate of the electrodeionization device is 5 to 15 m 3 / h.

5. The method for operating the electrodeionization device according to claim 4, wherein: The boron concentration of the water supply to be treated is 0.1 μg / L or more.

6. The method for operating the electrodeionization device according to claim 4, wherein: The conductivity of the treated water is 0.1-1 mS / m.

7. The method for operating an electrodeionization device according to any one of claims 3 to 6, wherein: The concentration of inorganic carbonic acid in the treated water is 50 to 1000 μg / L in terms of carbon.

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