Electric deionization apparatus and method for operating same

Abstract

This electric deionization apparatus 1 is formed by arranging sub-blocks 3A-3F side by side. Water supply ports 4A, 4B for arranging a water supply line 4 are formed at both upper ends of the cells of the sub-blocks 3A-3F. Concentrated water supply ports 6A, 6B for arranging a concentrated water supply line 6 are formed at both lower ends of the cells. Constant flow valves 11A, 11B are respectively provided on right and left sides of the concentrated water supply line 6, and manual valves 12A, 12B are respectively provided on right and left sides of a concentrated waste water outflow line 7. This electric deionization apparatus can efficiently produce high quality treated water.

Description

Electrodeionization apparatus and its operating method

[0001] The present invention relates to an electrodeionization apparatus and an operating method thereof, and more particularly to an electrodeionization apparatus and an operating method thereof that can efficiently produce high-quality treated water.

[0002] An electrodeionization device generally has cation exchange membranes and anion exchange membranes alternately arranged between a cathode and an anode, with the cation exchange membranes forming compartments to form deionization compartments and concentration compartments, which are then filled with ion exchange resin. Examples of ion exchange membranes, such as cation exchange membranes and anion exchange membranes, include heterogeneous membranes formed by adding a binder such as polystyrene to powdered ion exchange resin, homogeneous membranes formed by polymerizing styrene-divinylbenzene, and membranes formed by graft polymerization of various monomers with anion or cation exchange functions.

[0003] An electrodeionization apparatus having a configuration as shown in FIGS. 6 and 7 is disclosed in Japanese Patent Application Laid-Open No. 2003-222999.

[0004] 6, the electrodeionization device 21 has a plurality of anion exchange membranes 33 and cation exchange membranes 34 arranged alternately between electrodes (anodes 31 and cathodes 32) to form alternating concentration compartments 35 and deionization compartments 36. The deionization compartments 36 are filled with a mixture or multiple layers of ion exchangers (anion exchangers and cation exchangers) made of ion exchange resins, ion exchange fibers, graft exchangers, etc. The concentration compartments 35, positive electrode compartment 37, and cathode compartment 38 are also filled with ion exchangers.

[0005] This electrodeionization apparatus 21 is provided with a water-passing means (not shown) for passing water W1 to be treated through the deionization compartment 36 and extracting treated water W2, and a concentrated water-passing means (not shown) for passing concentrated water W3 through the concentration compartment 35. In this embodiment, concentrated water W3 is introduced into the concentration compartment 35 from the side of the deionization compartment 36 that is closer to the outlet for the treated water W2 and flows out from the side closer to the inlet of the deionization compartment 36, i.e., concentrated water W3 is introduced into the concentration compartment 35 from the direction opposite to the flow direction of the water W1 to be treated in the deionization compartment 36, and concentrated wastewater W4 is discharged. The document also describes that concentrated water W3 has a lower silica or boron concentration than the feedwater (water W1 to be treated), and is introduced into the concentration compartment from the side closer to the deionized water outlet of the deionization compartment and flows out from the side closer to the raw water inlet of the deionization compartment.

[0006] In particular, as shown in Figure 7, it is described as a preferred embodiment that a portion of the treated water W2 obtained from the deionization chamber 36 is used as concentrated water W3, and concentrated wastewater W4 with a reduced ion concentration is circulated.

[0007] Such electrodeionization devices are used as pure water producing devices in various industries, such as semiconductor chip manufacturing processes, thermal or nuclear power plants, petrochemical plants, and pharmaceutical manufacturing processes.

[0008] The semiconductor market in particular demands high quality produced water, often requiring a specific resistance of 15 MΩ cm or more and a high boron and silica removal rate. In recent years, there has also been a demand for operating conditions that take into account energy and water conservation in addition to high-purity treated water.

[0009] Xylem's IP-VNX-55EX-2 is a commercially available electrodeionization apparatus suitable for semiconductor manufacturing processes. As shown in Figure 8, this electrodeionization apparatus 40 includes sub-blocks 41 to 46 housed within a frame 50. Each of the sub-blocks 41 to 46 is formed with multiple pairs of deionization compartments and concentration compartments, each consisting of alternating cation exchange membranes CEM and anion exchange membranes AEM.

[0010] Sub-blocks 41 and 43 of this electrodeionization apparatus 40 each have 17 pairs of deionization compartments and concentration compartments, and sub-block 42 has 16 such pairs. Sub-blocks 44 and 46 each have 17 such pairs, and sub-block 45 has 16 such pairs. In Figure 8, "-" indicates the cathode compartment 47, and "+" indicates the cathode compartment 48. Reference numeral 49 denotes a power supply box.

[0011] In the operation method of electrodeionization apparatus 40 shown in Figure 8, feedwater (water to be treated) W1 and concentrated water W3 are supplied from the respective ports to sub-blocks 41 to 43. A portion of feedwater W1 passes through the water supply channels (upper head sections) of sub-blocks 41 to 43 and is supplied to the water supply channels (upper head sections) of sub-blocks 44 to 46. This feedwater passes through each desalination chamber of each sub-block 41 to 46, passes through the desalinated water collection channel (lower head section), and is taken out from the treated water outlet port as treated water W2.

[0012] Concentrated water is supplied to the heads (upper heads) of the sub-blocks 41 to 43, passes through each concentrating chamber of the sub-blocks 41 to 43, and is introduced into the concentrated water heads (lower heads) of the sub-blocks 44 to 46. The water is then passed through each concentrating chamber of the sub-blocks 44 to 46, passes through the upper heads of the concentrating chambers of the sub-blocks 44 to 46, and is discharged as concentrated wastewater W4 from the concentrated wastewater outlet ports. In other words, in the electrodeionization apparatus 40 shown in FIG. 8 , the feedwater W1 flows downward through all the deionization chambers. Meanwhile, the direction of the concentrated water W3 is downward in the first half (sub-blocks 41, 42, and 43) and upward in the second half (sub-blocks 44, 45, and 46). By reversing the flow direction of the concentrated water W3 between the sub-blocks 41 to 43 and the sub-blocks 44 to 46, the amount of concentrated wastewater W4 used is halved.

[0013] However, with the water flow method of the electrodeionization apparatus 40 shown in Figure 8, the difference in ion concentration between the lower part of the deionization compartment and the lower part of the concentration compartment in the sub-blocks 44 to 46 becomes large, which causes ions to move from the concentration compartment to the deionization compartment due to concentration diffusion, resulting in a deterioration in the quality of the treated water.

[0014] Therefore, the present applicant has filed patent applications for an electrodeionization apparatus as shown in FIG. 9 (Patent Documents 2 and 3). This electrodeionization apparatus 1 comprises sub-blocks 3A to 3F arranged side by side between frames 2, 2. Each sub-block 3A to 3F has multiple pairs of deionization compartments (not shown) and concentration compartments (not shown) formed by alternatingly arranged cation exchange membranes CEM and anion exchange membranes AEM. Water supply ports 4A and 4B are formed at both ends of one side (the upper side in the figure) of a cell in which these sub-blocks 3A to 3F are connected, and through which water supply lines 4 are installed to pass water W1 to be treated into the deionization compartments. Treated water outlet ports 5A and 5B are formed at both ends of the other side (the lower side in the figure) of the cell, and through which treated water outlet lines 5 are installed to discharge treated water W2 (deionized water) treated in the deionization compartments. Water supply line 4 branches in each of sub-blocks 3A to 3F, and connects to the upper side of each deionization compartment as a treated water inlet branch pipe, while a treated water outlet pipe is connected to the lower side of each deionization compartment, and these treated water outlet pipes merge into treated water outlet line 5. This makes it possible to supply treated water W1 from the upper side of each deionization compartment from water supply ports 4A, 4B via water supply line 4, and further to discharge treated water W2 from the lower side of each deionization compartment via treated water outlet line 5 from the treated water outlet ports 5A, 5B.

[0015] Concentrated water supply ports 6A, 6B are formed at both ends of the lower side of the cell in which the sub-blocks 3A to 3F are connected, and a concentrated water supply line 6 is provided for passing concentrated water W3 through the concentrating chambers. Concentrated waste water outlet ports 7A, 7B are formed at both ends of the upper side of the cell, and a concentrated water inlet branch pipe is provided for discharging concentrated waste water W4. The concentrated water supply line 6 branches off in each of the sub-blocks 3A to 3F and connects to the lower side of each concentrating chamber as a concentrated water inlet branch pipe. Concentrated waste water outlet pipes are connected to the upper side of each concentrating chamber, and these concentrated waste water outlet pipes merge into the concentrated waste water outlet line 7. This allows concentrated water W3 to be supplied from the concentrated water supply ports 6A, 6B through the concentrated water supply line 6 to the lower side of each concentrating chamber, and concentrated waste water W4 can be discharged from the upper side of each concentrating chamber through the concentrated waste water outlet line 7 and from the concentrated waste water outlet ports 7A, 7B.

[0016] In the electrodeionization apparatus 1 shown in Figure 9, sub-blocks 3A, 3C, 3D, and 3F each have a plurality of pairs of dilution compartments and concentration compartments (e.g., 17), while sub-blocks 3B and 3E each have one less pair of dilution compartments and concentration compartments (e.g., 16). In Figure 9, "-" indicates the cathode compartment 8, "+" indicates the cathode compartment 9, and reference numeral 10 indicates the power supply box.

[0017] JP 2002-205069 A JP 2023-136089 A Japanese Patent No. 7460012 A

[0018] The electrodeionization devices described in Patent Documents 2 and 3 were able to suppress the deterioration of the quality of treated water in an electrodeionization device as shown in FIG.

[0019] In the electrodeionization apparatuses of Patent Documents 2 and 3, a constant flow valve is provided at the base end of the concentrated water supply line 6 to limit the amount of water supplied to the concentrated water supply line 6 in order to minimize water consumption by the concentrated wastewater W4. The concentrated wastewater outlet line 7 is divided into two parts, left and right, as shown in the figure, and the concentrated wastewater W4 is discharged from concentrated wastewater outlet ports 7A and 7B. In other words, the concentrating chambers are also divided into one discharged from concentrated wastewater outlet port 7A and the other discharged from concentrated wastewater outlet port 7B. However, as a result of studies by the present inventors, it was found that the flow rates at the concentrated wastewater outlet ports 7A and 7B can differ due to factors such as slight differences in the filling rate of the ion exchange resin in the concentrating chambers. This results in a lower flow rate of concentrated water in the concentrating chamber connected to the port with the lower flow rate, making it more likely for scale to form.

[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] In order to achieve the above object, firstly, the present invention provides an electrodeionization apparatus comprising a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes arranged between the cathode and anode, and a plurality of deionization compartments and concentration compartments partitioned by these cation exchange membranes and anion exchange membranes, the deionization compartments and the concentration compartments being filled with ion exchange resin, and the apparatus having means for passing water to be treated through the plurality of deionization compartments to extract deionized water and a concentrated water passing means for passing concentrated water through the concentration compartments, wherein one side of each deionization compartment is connected to a water inlet branch pipe branched in sequence from a water supply line, and the other side of each deionization compartment is connected to a treated water outlet pipe, the outlet pipes of the concentrating chambers merge into a treated water outlet line, the water to be treated can be supplied from both sides of the water supply line, the other side of each concentrating chamber is connected to a concentrated water inlet branch pipe branching off in sequence from the concentrated water supply line, one side of each concentrating chamber is connected to a concentrated wastewater outlet pipe, and these concentrated wastewater outlet pipes merge into the concentrated wastewater outlet line, the concentrated water can be supplied from both sides of the concentrated water supply line and the concentrated water can be discharged from both sides of the concentrated wastewater outlet line, and a flow rate control means is provided for controlling the flow rate discharged from both sides of the concentrated wastewater outlet line (Invention 1).

[0022] According to this invention (Invention 1), the flow rate of the concentrated wastewater outlet line is controlled to be the same by the flow control means, thereby equalizing the flow rate of concentrated water in each concentration compartment. Therefore, by optimizing the concentrated water supplied from both sides of the concentrated water supply line, it is possible to suppress the formation of scale in the concentration compartment.

[0023] In the above invention (Invention 1), the flow rate of the treated water in the electrodeionization device is 5 to 50 m ３ / h (Invention 2).

[0024] According to this invention (Invention 2), even if the amount of concentrated water is reduced, it is possible to suppress the generation of scale in the concentration compartment. Therefore, the amount of treated water in the deionization compartment, where the ratio of concentrated water to the water to be treated tends to be large, is reduced to 50 m ３ / h or less, especially 25m３ This can be suitably applied to electrodeionization apparatuses with a relatively small amount of treated water per hour or less.

[0025] Secondly, the present invention provides a water treatment system comprising a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes arranged between the cathode and anode, and a plurality of deionization compartments and concentration compartments partitioned by these cation exchange membranes and anion exchange membranes, the deionization compartments and the concentration compartments being filled with ion exchange resin, and comprising means for passing water to be treated through the plurality of deionization compartments to extract deionized water and concentrated water passing means for passing concentrated water through the concentration compartments, one side of each deionization compartment is connected to a water to be treated inlet branch pipe branched in sequence from a water to be treated supply line, and the other side of each deionization compartment is connected to a treated water outlet pipe, and these treated water outlet pipes merge into the treated water outlet line, so that the water to be treated can be supplied from both sides of the water to be treated supply line, and the other side of each concentration compartment is connected to a concentrated water In a method for operating an electrodeionization apparatus, the apparatus has inlet branch pipes communicating with each other, one side of each concentration chamber communicating with a concentrated wastewater outlet pipe, each of which merges into a concentrated wastewater outlet line, the concentrated water being able to be supplied from both sides of the concentrated water supply line and discharged from both sides of the concentrated wastewater outlet line, and the apparatus has a flow control means for controlling the flow rate of the concentrated wastewater outlet line, wherein the water to be treated is supplied from both sides of the supply line and treated water is taken out from the outlet line, concentrated water is supplied from both sides of the concentrated water supply line, and concentrated wastewater is discharged from both sides of the concentrated wastewater outlet line, and the flow rate on both sides of the concentrated wastewater outlet line is controlled by the flow control means to be equal (Invention 3).

[0026] According to this invention (Invention 3), by controlling the flow rate of the concentrated wastewater outflow line to be equal by the flow rate control means, the flow rate of the concentrated water in each concentration compartment is equalized, and therefore, by optimizing the concentrated water supplied from both sides of the concentrated water supply line, it is possible to suppress the occurrence of scale in the concentration compartment. Note that in this specification, "the flow rates on both sides of the concentrated wastewater outflow line being equal" does not mean only that they are completely the same, but also that they are different from the flow rate (m ３ / h) may be different.

[0027] In the above invention (Invention 3), the flow rate of the treated water in the electrodeionization device is 5 to 50 m ３ / h (Invention 4).

[0028] According to this invention (Invention 4), even if the amount of concentrated water is reduced, it is possible to suppress the generation of scale in the concentration compartment. Therefore, the amount of treated water in the deionization compartment, where the ratio of concentrated water to the water to be treated tends to be large, is reduced to 50 m ３ / h or less, especially 25m ３ This allows the electrodeionization apparatus to be suitably operated with a relatively small amount of treated water, such as 10 ...

[0029] In the electrodeionization apparatus of the present invention, the flow direction of the water to be treated in the deionization compartments is opposite to the flow direction of the concentrated water to the concentrating compartments, and the concentrated water can be supplied from both sides of the concentrated water supply line.The concentrated wastewater outlet line is open in both directions so as to divide each concentrating compartment in half, allowing the concentrated water to be discharged from both sides of this outlet line.A flow rate control means is provided for controlling the flow rate of the concentrated wastewater outlet line.By controlling the flow rate of the concentrated wastewater outlet line to be equal using the flow rate control means, the flow rate of the concentrated water in each concentrating compartment is equalized.Therefore, by optimizing the concentrated water supplied from both sides of the concentrated water supply line, it is possible to suppress the formation of scale in the concentrating compartments.

[0030] FIG. 1 is a schematic diagram showing the configuration of an electrodeionization apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of an electrodeionization apparatus according to a second embodiment of the present invention. FIG. 3 is a schematic diagram showing the configuration of an electrodeionization apparatus according to a third embodiment of the present invention. FIG. 4 is a schematic diagram showing the configuration of an electrodeionization apparatus according to a fourth embodiment of the present invention. FIG. 5 is a schematic diagram showing the configuration of an electrodeionization apparatus according to a fifth embodiment of the present invention. FIG. 6 is a schematic diagram showing the configuration of a conventional electrodeionization apparatus (Patent Document 1). FIG. 7 is a schematic diagram showing the flow of water in the desalting compartments and concentrating compartments of the conventional electrodeionization apparatus (Patent Document 1). FIG. 8 is a schematic diagram showing the configuration of a conventional (commercially available) electrodeionization apparatus. FIG. 9 is a schematic diagram showing the configuration of a conventional electrodeionization apparatus (Patent Document 2).

[0031] The electrodeionization apparatus and the operating method thereof according to the present invention will now be described with reference to the accompanying drawings.

[0032] First Embodiment [Electrodeionization Apparatus] Figure 1 shows an electrodeionization apparatus according to a first embodiment of the present invention. In Figure 1, the electrodeionization apparatus 1 comprises sub-blocks 3A to 3F arranged side by side between frames 2, 2. Each sub-block 3A to 3F is formed with multiple pairs of deionization compartments (not shown) and concentration compartments (not shown) formed by alternatingly arranged cation exchange membranes CEM and anion exchange membranes AEM. These deionization compartments and concentration compartments are filled with ion exchange resin (e.g., a mixed resin of anion exchange resin and cation exchange resin).

[0033] At both ends of one side (the upper side in the figure) of the cell in which these sub-blocks 3A to 3F are connected, water supply ports 4A, 4B are formed on both the left and right sides in the figure, for accommodating water supply lines 4 for passing water to be treated W1 to the deionization compartments, while at both ends of the other side (the lower side in the figure) of the cell, treated water outlet ports 5A, 5B are formed on both the left and right sides, for accommodating treated water outlet lines 5 for discharging treated water W2 as deionized water treated in the deionization compartments. Water supply line 4 branches off in each of sub-blocks 3A to 3F, and connects to the upper side of each deionization compartment as a treated water inlet branch pipe, and treated water outlet pipes are connected to the lower side of each deionization compartment, and these treated water outlet pipes merge into treated water outlet line 5. This allows the treated water W1 to be supplied from the upper side of each desalination chamber via the water supply line 4 from the left and right water supply ports 4A, 4B (both sides), and the treated water W2 can be discharged from the lower side of each desalination chamber via the treated water outflow line 5 from the left and right treated water outflow ports 5A, 5B.

[0034] Concentrated water supply ports 6A, 6B are formed on both left and right sides of the lower end of the cell in which the sub-blocks 3A to 3F are connected, and the concentrated water supply lines 6 are provided for passing concentrated water W3 through the concentrating chambers. Concentrated wastewater outlet ports 7A, 7B are formed on both left and right sides of the upper end of the cell, and the concentrated wastewater outlet lines 7 are provided for discharging concentrated wastewater W4. The concentrated wastewater outlet lines 7 are provided in a pair on the left and right sides so as to divide the concentrating chambers into two. The concentrated water supply line 6 branches off in each of the sub-blocks 3A to 3F and connects to the lower side of each concentrating chamber as a concentrated water inlet branch pipe. Concentrated wastewater outlet pipes are connected to the upper side of each concentrating chamber, and these concentrated wastewater outlet pipes merge into the concentrated wastewater outlet line 7. This allows concentrated water W3 to be supplied from the lower side of each concentrating compartment via concentrated water supply line 6 from concentrated water supply ports 6A, 6B, and concentrated wastewater W4 to be discharged from the upper side of each concentrating compartment via concentrated wastewater outlet line 7 from concentrated wastewater outlet ports 7A, 7B. In this embodiment, constant flow valves 11A, 11B are provided on both the left and right sides of concentrated water supply line 6, and manual valves 12A, 12B are provided on both the left and right sides of concentrated wastewater outlet line 7 as flow rate control means.

[0035] In the electrodeionization apparatus 1 shown in Figure 1, sub-blocks 3A, 3C, 3D, and 3F each have a plurality of pairs of dilution compartments and concentration compartments (e.g., 17), while sub-blocks 3B and 3E each have one less pair of dilution compartments and concentration compartments (e.g., 16). Note that in Figure 1, "-" indicates the anode compartment 8, "+" indicates the cathode compartment 9, and reference numeral 10 indicates the power supply box.

[0036] [Operation Method of Electrodeionization Apparatus] Next, an operation method of the electrodeionization apparatus 1 having the above-described configuration will be described.

[0037] First, water to be treated W1 is supplied from above to the deionization chambers of sub-blocks 3A to 3F via water supply line 4 from water supply ports 4A and 4B, and concentrated water W3 is supplied from below to each concentration chamber via concentrated water supply ports 6A and 6B and concentrated water supply line 6. Water to be treated W1 passes through the deionization chambers of each sub-block 3A to 3F from top to bottom in the figure, passes through each treated water outlet pipe and treated water outlet line 5, and is discharged from treated water outlet ports 5A and 5B. Concentrated water W3 is supplied from both the left and right sides of concentrated water supply line 6, passes through the concentration chambers of each sub-block 3A to 3F from bottom to top in the figure, passes through each concentrated wastewater outlet pipe and concentrated wastewater outlet line 7, and is discharged from concentrated wastewater outlet ports 7A and 7B. In this case, due to factors such as slight differences in the filling rate of the ion exchange resin in each concentration compartment, the flow resistance of the concentrated water W3 in each concentration compartment varies, resulting in different flow rates of the concentrated water W3 between the concentrated wastewater outlet ports 7A and 7B. The flow rate of the concentrated water W3 in the concentration compartment with the lower flow rate is lower, which makes it more likely to produce scale. Therefore, in this embodiment, the flow rates of the concentrated water W3 supplied from the concentrated water supply ports 6A and 6B on both sides of the concentrated water supply line 6 are set equal by the constant flow valves 11A and 11B. Furthermore, the manual valves 12A and 12B are adjusted so that the flow rates of the concentrated water W3 discharged from the concentrated wastewater outlet ports 7A and 7B are equal. This allows the amount of concentrated water flowing through each concentration compartment to be uniform, which in turn allows the tendency for scale formation in each concentration compartment to be uniform and ultimately suppresses scale formation in each concentration compartment.

[0038] In the operation method of the electrodeionization apparatus 1 of this embodiment as described above, the concentrated water W3 may be a fraction of the treated water W2, or the same water as the water to be treated W1, such as water treated by an RO membrane, may be used. The flow rate of the treated water W2 (demineralization chamber flow rate) through the sub-blocks 3A to 3F is set to 5 to 50 m ３ / h, especially 5 to 25 m ３ / h, and another 5 to 15 m ３ / h. The flow rate of the treated water W2 (flow rate in the desalination chamber) is preferably 5 m ３ At less than 50 m / h, the amount of treated water is too small to be practical. ３ / h, it becomes difficult to achieve a compact configuration as in this embodiment. Furthermore, the flow rate of concentrated wastewater W4 relative to the flow rate of treated water W2 is preferably 2.5 to 10 volume %, and particularly about 5 volume %. If the flow rate of concentrated wastewater W4 is less than 2.5 volume %, the amount of concentrated wastewater W4 is too small, resulting in a high concentration of ions flowing in from the deionization chambers, and back diffusion cannot be ignored, making it likely to deteriorate the quality of treated water W2. On the other hand, if the flow rate exceeds 10 volume %, the amount of concentrated water W3 supplied becomes too large, which is undesirable in terms of water utilization efficiency.

[0039] The water flow rate SV of the deionization compartment is preferably 70 to 150 / h, particularly 100 to 120 / h. The water flow rate SV of the concentration compartment is preferably 5 to 50 / h, particularly 10 to 25 / h. The recovery rate is preferably 80 to 99%, particularly 90 to 95%. The applied current is 0.15 to 2.30 A / (m ３ / h), especially 0.7A / (m ３ / h) to 1.2A / (m ３ / h) is preferred.

[0040] In this embodiment, water to be treated W1 is passed through all deionization compartments in a downward flow as shown in the figure, while concentrated water W3 is passed through all concentration compartments in an upward flow as shown in the figure.

[0041] The conductivity of the water to be treated W1 (feedwater) is preferably 0.1 to 1 mS / m, particularly 0.1 to 0.5 mS / m. If the conductivity of the water to be treated W1 (feedwater) exceeds 1 mS / m, back diffusion from the concentration compartment to the deionization compartment is likely to occur, which is undesirable because it is likely to cause a deterioration in the quality of the treated water W2.

[0042] Furthermore, the inorganic carbonate concentration of the water to be treated W1 (feedwater) is preferably 50 to 1000 μg / L as C. If the inorganic carbonate concentration of the water to be treated W1 (feedwater) exceeds 1000 μg / L as C, the carbonate concentration will be too high, making it more likely that back diffusion will occur from the concentration compartment to the deionization compartment, which will not only likely lead to a deterioration in the quality of the treated water W2 but will also make it more likely that carbonates such as calcium carbonate will precipitate on electrodes, etc.

[0043] The water to be treated W1 (supply water) described above can be industrial water, city water, well water, etc., which has been pretreated as necessary and then treated with a water treatment device including a reverse osmosis membrane device. It is preferable to appropriately sense the conductivity, boron concentration, and inorganic carbonate concentration of the treated water from this reverse osmosis membrane device and confirm that they are within the above-mentioned ranges before use.

[0044] Second Embodiment [Electrodeionization Apparatus] Fig. 2 shows an electrodeionization apparatus according to a second embodiment of the present invention. The electrodeionization apparatus 1 shown in Fig. 2 has basically the same configuration as that of the first embodiment described above and can be operated under the same conditions. Therefore, the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

[0045] 2, the electrodeionization apparatus 1 is configured such that concentrated water W3 is supplied from concentrated water supply ports 6A and 6B via a concentrated water supply line 61 that branches to the left and right in the figure. A constant flow valve 11C is provided just before the branching of the concentrated water supply line 61, and the concentrated water supply line 6 does not have the constant flow valves 11A and 11B. The configuration is the same as that of the first embodiment.

[0046] [Operation Method of Electrodeionization Apparatus] Next, an operation method of the electrodeionization apparatus 1 having the above-described configuration will be described.

[0047] First, water to be treated W1 is supplied from above to the deionization compartments of sub-blocks 3A to 3F via water supply line 4 from water supply ports 4A and 4B, and concentrated water W3 is supplied from concentrated water supply line 61 and supplied to each concentration compartment from below. Water to be treated W1 passes through the deionization compartments of each sub-block 3A to 3F from top to bottom in the figure, passes through each treated water outlet pipe and treated water outlet line 5, and is discharged from treated water outlet ports 5A and 5B. Concentrated water W3 is supplied from both the left and right sides of concentrated water supply line 6, passes through the concentration compartments of each sub-block 3A to 3F from bottom to top in the figure, passes through each concentrated wastewater outlet pipe and concentrated wastewater outlet line 7, and is discharged from concentrated wastewater outlet ports 7A and 7B. At this time, due to factors such as slight differences in the filling rate of the ion exchange resin in each concentration compartment, the flow resistance of concentrated water W3 in each concentration compartment varies, resulting in different flow rates between concentrated wastewater outlet ports 7A and 7B. The flow rate of concentrated water in the concentration compartment with the lower flow rate port is lower, making it more likely to produce scale. Therefore, in this embodiment, the flow rate of concentrated water W3 supplied from concentrated water supply line 61 is controlled by constant flow valve 11C, and manual valves 12A and 12B are adjusted so that the flow rates of concentrated water W3 discharged from concentrated wastewater outlet ports 7A and 7B are the same. This makes it possible to equalize the amount of concentrated water flowing through each concentration compartment, thereby equating the tendency for scale formation in each concentration compartment and ultimately suppressing scale formation in each concentration compartment.

[0048] Third Embodiment [Electrodeionization Apparatus] Fig. 3 shows an electrodeionization apparatus according to a third embodiment of the present invention. The electrodeionization apparatus 1 shown in Fig. 3 has basically the same configuration as that of the first embodiment described above and can be operated under the same conditions. Therefore, the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

[0049] In Figure 3, the electrodeionization apparatus 1 has the same configuration as in the first embodiment described above, except that it does not have the constant flow valves 11A and 11B on the concentrated water supply line 6, and constant flow valves 13A and 13B are provided on both the left and right sides of the concentrated wastewater outflow line 7 as flow control means instead of the manual valves 12A and 12B.

[0050] [Operation Method of Electrodeionization Apparatus] Next, an operation method of the electrodeionization apparatus 1 having the above-described configuration will be described.

[0051] First, water to be treated W1 is supplied from above to the deionization compartments of sub-blocks 3A to 3F via water supply line 4 from water supply ports 4A and 4B, and concentrated water W3 is supplied from concentrated water supply line 6 to each concentration compartment from below. Water to be treated W1 passes through the deionization compartments of each sub-block 3A to 3F from top to bottom in the figure, passes through each treated water outlet pipe and treated water outlet line 5, and is discharged from treated water outlet ports 5A and 5B. Concentrated water W3 passes through the concentration compartments of each sub-block 3A to 3F from both the left and right sides of concentrated water supply line 6 from bottom to top in the figure, passes through each concentrated wastewater outlet pipe and concentrated wastewater outlet line 7, and is discharged from concentrated wastewater outlet ports 7A and 7B. In this case, due to factors such as slight differences in the filling rate of the ion exchange resin in each concentration compartment, the flow resistance of concentrated water W3 in each concentration compartment varies, resulting in different flow rates between concentrated wastewater outlet ports 7A and 7B. The flow rate of concentrated water in the concentration compartment with the lower flow rate is lower, making it more likely for scale to form. Therefore, in this embodiment, constant flow valves 13A and 13B are provided to maintain a constant flow rate of concentrated water W3 discharged from concentrated wastewater outlet ports 7A and 7B. This allows the amount of concentrated water flowing through each concentration compartment to be uniform, which in turn allows the tendency for scale formation in each concentration compartment to be uniform and ultimately suppresses scale formation in each concentration compartment.

[0052] Fourth Embodiment [Electrodeionization Apparatus] Figure 4 shows an electrodeionization apparatus according to a fourth embodiment of the present invention. The electrodeionization apparatus of this embodiment has essentially the same configuration as the second embodiment described above. Therefore, the same components are designated by the same reference numerals and detailed descriptions are omitted. In Figure 4, the electrodeionization apparatus 1 comprises sub-blocks 3A-3G arranged side by side between frames 2. Each sub-block 3A-3G is formed by alternatingly arranged cation exchange membranes CEM and anion exchange membranes AEM, forming multiple pairs of deionization compartments (not shown) and concentration compartments (not shown). These deionization compartments and concentration compartments are filled with ion exchange resin (e.g., a mixture of anion exchange resin and cation exchange resin).

[0053] At both ends of one side (the upper side in the figure) of each cell in which these sub-blocks 3A to 3G are connected, there are formed water supply ports 4A, 4B for arranging water supply lines 4 for passing water to be treated W1 to the deionization compartments, while at both ends of the other side (the lower side in the figure) of the cell, there are formed treated water outlet ports 5A, 5B for arranging treated water outlet lines 5 for discharging treated water W2 as deionized water treated in the deionization compartments. The water supply line 4 branches in each of the sub-blocks 3A to 3G and connects to the upper side of each deionization compartment as a treated water inlet branch pipe, and treated water outlet pipes communicate with the lower side of each deionization compartment, and these treated water outlet pipes merge into treated water outlet line 5. This allows the water to be treated W1 to be supplied from the upper side of each deionization compartment from the water supply ports 4A, 4B via the water supply lines 4 and then discharged from the lower side of each deionization compartment via treated water outlet line 5 through the treated water outlet ports 5A, 5B.

[0054] Concentrated water supply ports 6A, 6B are formed at both ends of the lower side of the cell in which the sub-blocks 3A to 3G are connected, and these ports are equipped with concentrated water supply lines 6 for supplying concentrated water W3 as concentrated water to the concentrating compartments. Concentrated water discharge outlet ports 7A, 7B are formed at both ends of the upper side of the cell, and these ports are equipped with concentrated water discharge outlet lines 7 for discharging concentrated waste water W4. The concentrated water supply line 6 branches off in each of the sub-blocks 3A to 3G and connects to the lower sides of the concentrating compartments as concentrated water inlet branch pipes. Concentrated water discharge outlet pipes are connected to the upper sides of the concentrating compartments, and these concentrated water discharge outlet pipes merge into the concentrated water discharge outlet line 7. This allows concentrated water W3 to be supplied from the lower sides of the concentrating compartments from the concentrated water supply ports 6A, 6B via the concentrated water supply line 6, and further allows concentrated water W3 to be discharged from the upper sides of the concentrating compartments via the concentrated water discharge outlet line 7 through the concentrated water discharge outlet ports 7A, 7B.

[0055] In this embodiment, an anode chamber (negative electrode) 8 is disposed on the left end side between the frames 2, 2 in the drawing, and an anode chamber (anode) 9 is provided on the right end side, forming a single block configuration of sub-blocks 3A to 3G, and a closing plate 11 is provided in the middle of the concentrated wastewater outflow line 7, so that the flow in the concentrated wastewater outflow line 7 is divided into concentrated wastewater outflow ports 7A and 7B. Reference numeral 10 denotes a power supply box.

[0056] By using a single block configuration with the negative electrode 8 on the left end side and the anode 9 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 first embodiment, when a pair of anode chambers (anodes) 9 is arranged in the center, and the number of sub-blocks 3A... can be increased, allowing the flow rate of treated water W2 (demineralization chamber flow rate) to 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 is longer, a higher voltage, particularly a voltage approximately twice as high as that in the first embodiment, must be applied, and the amount of current is also increased, resulting in different power supply conditions. However, the operating method can otherwise be substantially the same as that of the first embodiment described above.

[0057] 4, the electrodeionization apparatus 1 is configured such that concentrated water W3 is supplied from the concentrated water supply ports 6A and 6B via a concentrated water supply line 61 that branches to the left and right in the figure. A constant flow valve 11C is provided just before the branching of the concentrated water supply line 61.

[0058] [Operating Method of Electrodeionization Apparatus] Next, a method of operating the electrodeionization apparatus having the above-described configuration will be described.

[0059] First, water to be treated W1 is supplied from above to the deionization chambers of sub-blocks 3A to 3G via water supply line 4 from water supply ports 4A and 4B, and concentrated water W3 is supplied from concentrated water supply line 61 and supplied to each concentration chamber from below. Water to be treated W1 passes through the deionization chambers of each sub-block 3A to 3G from top to bottom in the figure, passes through each treated water outlet pipe and treated water outlet line 5, and is discharged from treated water outlet ports 5A and 5B. Concentrated water W3 is supplied from both the left and right sides of concentrated water supply line 6, passes through the concentration chambers of each sub-block 3A to 3F from bottom to top in the figure, passes through each concentrated wastewater outlet pipe and concentrated wastewater outlet line 7, and is discharged from concentrated wastewater outlet ports 7A and 7B. In this case, due to factors such as slight differences in the filling rate of the ion exchange resin in each concentration compartment, the flow resistance of the concentrated water W3 in each concentration compartment varies, resulting in different flow rates between the concentrated wastewater outlet ports 7A and 7B. The flow rate of the concentrated water in the concentration compartment with the lower flow rate port is lower, making it more likely to produce scale. Therefore, in this embodiment, the flow rate of the concentrated water W3 supplied from the concentrated water supply line 61 is controlled by the constant flow valve 11C, and the manual valves 12A and 12B on both sides are adjusted so that the flow rates of the concentrated water W3 discharged from the concentrated wastewater outlet ports 7A and 7B are set to a flow rate ratio corresponding to the number of sub-blocks 3A to 3G. This allows the amount of concentrated water flowing through each concentration compartment to be uniform, thereby equating the tendency for scale formation in each concentration compartment and ultimately suppressing scale formation in each concentration compartment.

[0060] In the electrodeionization apparatus 1 of this embodiment as described above, the concentrated water W3 may be a fraction of the treated water W2, or the same water as the water to be treated W1, such as water treated by an RO membrane, may be used. The flow rate of the treated water W2 (demineralization chamber flow rate) through the sub-blocks 3A to 3G is set to 5 to 50 m ３ / h, especially 5 to 25 m ３ / h, and another 5 to 15 m ３ / h. The flow rate of the treated water W2 (flow rate in the desalination chamber) is preferably 5 m ３ At less than 50 m / h, the amount of treated water is too small to be practical. ３ / h, especially 25m ３ / h, the flow rate of the treated water W2 increases, and the benefits are not sufficient compared to when the treated water W2 is used as the concentrated water W3. Furthermore, the flow rate of the concentrated wastewater W4 relative to the feedwater flow rate (flow rate of the treated water W2 + flow rate of the concentrated wastewater W4) is preferably 2.5 to 10 volume %, and particularly about 5 volume %. If the flow rate of the concentrated wastewater W4 is less than 2.5 volume %, the amount of concentrated wastewater W4 is too small, resulting in a high ion concentration flowing in from the deionization chamber, and back diffusion cannot be ignored, making it likely to deteriorate the quality of the treated water W2. On the other hand, if the flow rate exceeds 10 volume %, the amount of concentrated water W3 increases, and using the water to be treated W1 as concentrated water W3 results in an excessively large amount of feedwater, which is not preferable.

[0061] Fifth Embodiment [Electrodeionization Apparatus] Fig. 5 shows an electrodeionization apparatus according to a third embodiment of the present invention. In Fig. 5, the electrodeionization apparatus has the same configuration as that of the fourth embodiment, except that the constant flow valve 11C of the concentrated water supply line 61 is not provided, and constant flow valves 13A and 13B are provided on both the left and right sides of the concentrated wastewater outlet line 7 as flow control means instead of manual valves.

[0062] [Operating Method of Electrodeionization Apparatus] Next, a method of operating an electrodeionization apparatus having the above-described configuration will be described. First, water to be treated W1 is supplied from the water supply ports 4A and 4B to the deionization compartments of sub-blocks 3A to 3G from above via water supply line 4. Concentrated water W3 is also supplied from concentrated water supply line 61 to each concentrating compartment from below via concentrated water supply line 6. The water to be treated W1 passes through the deionization compartments of each sub-block 3A to 3G from top to bottom in the figure, passes through each treated water outlet pipe, passes through treated water outlet line 5, and is discharged from treated water outlet ports 5A and 5B. Concentrated water W3 passes through the concentrating compartments of each sub-block 3A to 3F from both the left and right sides of concentrated water supply line 6 from bottom to top in the figure, passes through each concentrated wastewater outlet pipe, passes through concentrated wastewater outlet line 7, and is discharged from concentrated wastewater outlet ports 7A and 7B. In this case, due to factors such as slight differences in the filling rate of the ion exchange resin in each concentration compartment, the flow resistance of concentrated water W3 in each concentration compartment varies, resulting in different flow rates between the concentrated wastewater outlet ports 7A and 7B. The flow rate of concentrated water in the concentration compartment with the lower flow rate port is lower, making it more likely to produce scale. Therefore, in this embodiment, constant flow valves 13A and 13B are provided on both the left and right sides of the concentrated wastewater outlet line 7 to set the flow rates of concentrated water W3 discharged from the concentrated wastewater outlet ports 7A and 7B to a flow rate ratio corresponding to the number of sub-blocks 3A to 3G. This allows the amount of concentrated water flowing through each concentration compartment to be uniform, thereby equating the tendency for scale formation in each concentration compartment and ultimately suppressing scale formation in each concentration compartment.

[0063] The electrodeionization apparatus and its operating method of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiment and various modifications are possible. For example, although six sub-blocks are installed in Figure 1 and seven in Figure 4, the number of sub-blocks is not limited to six and may be approximately one to twelve. Furthermore, the number of pairs of deionization compartments and concentration compartments in one sub-block may be approximately one to 100.

[0064] REFERENCE SIGNS LIST 1 Electrodeionization apparatus 2 Frame 3A to 3G Sub-block 4 Water supply line 4A, 4B Water supply port 5 Treated water outflow line 5A, 5B Treated water outflow port 6 Concentrated water supply line 61 Concentrated water supply line 6A, 6B Concentrated water supply port 7 Concentrated wastewater outflow line 7A, 7B Concentrated wastewater outflow port 8 Anode chamber 9 Cathode chamber 10 Power supply box 11A, 11B Constant flow valve (flow rate control means) 11C Constant flow valve (flow rate control means) 12A, 12B Manual valve (flow rate control means) 13A, 13B Constant flow valve (flow rate control means) W1 Water to be treated (supply water) W2 Treated water W3 Concentrated water W4 Concentrated wastewater

Claims

1. An electrodeionization apparatus comprising a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes arranged between the cathode and anode, and a plurality of deionization compartments and concentration compartments partitioned by these cation exchange membranes and anion exchange membranes, the deionization compartments and the concentration compartments filled with ion exchange resin, a means for passing water to be treated through the plurality of deionization compartments to extract deionized water, and a concentrated water passing means for passing concentrated water through the concentration compartments, wherein one side of each deionization compartment is connected to a water inlet branch pipe branched in sequence from a water supply line, and the other side of each deionization compartment is connected to a treated water outlet pipe, and each treated water outlet pipe merges into the treated water outlet line, so that the water to be treated can be supplied from both sides of the water supply line, a concentrated water inlet branch pipe branching in turn from a concentrated water supply line is connected to the other side of each of the concentration compartments, a concentrated wastewater outlet pipe is connected to one side of each of the concentration compartments, and each of these concentrated wastewater outlet pipes merges into a concentrated wastewater outlet line, so that the concentrated water can be supplied from both sides of the concentrated water supply line and can be discharged from both sides of the concentrated wastewater outlet line; and an electrodeionization apparatus having a flow rate control means for controlling the flow rate discharged from both sides of the concentrated wastewater outlet line.

2. The flow rate of the treated water from the electrodeionization device is 5 to 50 m ３ 2. The electrodeionization apparatus of claim 1, wherein the average particle size is 1000 sq m / h.

3. A system comprising a cathode and an anode, a plurality of cation exchange membranes and anion exchange membranes arranged between the cathode and anode, and a plurality of deionization compartments and concentration compartments partitioned by these cation exchange membranes and anion exchange membranes, the deionization compartments and the concentration compartments filled with ion exchange resin, a means for passing water to be treated through the plurality of deionization compartments to extract deionized water, and a concentrated water passing means for passing concentrated water through the concentration compartments, one side of each deionization compartment is connected to a water inlet branch pipe branched in sequence from a water supply line, and the other side of each deionization compartment is connected to a treated water outlet pipe, and each of these treated water outlet pipes is connected to a treated water outlet line. a concentrated wastewater outlet pipe connected to one side of each of the concentration chambers, each of which merges into a central inlet and outlet pipes for concentrated wastewater, so that the concentrated water can be supplied from both sides of the concentrated water supply line and can be discharged from both sides of the concentrated wastewater outlet line; and a flow control means for controlling the flow rate of the concentrated wastewater outlet line, the method comprising: supplying the water to be treated from both sides of the supply line and extracting treated water from the outlet line; supplying concentrated water from both sides of the concentrated water supply line and discharging concentrated wastewater from both sides of the concentrated wastewater outlet line; and controlling the flow rate of the concentrated wastewater outlet line to be equal by the flow control means.

4. The flow rate of the treated water from the electrodeionization device is 5 to 50 m ３ 4. The method of claim 3, wherein the total amount of the electrodeionization system is 1000 kJ / h.

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