Electrodialysis device, electrodialysis method, waste liquid treatment device, and waste liquid treatment method

Abstract

Provided is an electrodialysis device which can prevent the formation of scale on the surface of an ion exchange membrane and can perform stable acid recovery without cost. An electrodialysis device having at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane in this order, the electrodialysis device comprising: an anode chamber demarcated by the anode and the first bipolar membrane; an acid recovery chamber demarcated by the first bipolar membrane and the anion exchange membrane; a desalination chamber defined by the anion exchange membrane and the cation exchange membrane; the waste acid chamber is divided by the cation exchange membrane and the second bipolar membrane; and a cathode chamber demarcated by the second bipolar membrane and the cathode, and the electrodialysis device supplies water to the acid recovery chamber, supplies an acidic solution to the desalination chamber, and supplies waste acid to the waste acid chamber to perform electrodialysis treatment.

Description

Technical Field

[0001] This invention relates to an electrodialysis apparatus, an electrodialysis method, a waste liquid treatment apparatus, and a waste liquid treatment method. Background Technology

[0002] In the past, ion exchangers have been used for various purposes, including, for example, in pure water production systems. Typically, pure water production systems have cation exchanger filling units, decarbonation units, and anion exchanger filling units. By passing raw water through these units sequentially, cations are removed from the water in the cation exchanger filling unit, carbon dioxide is removed in the decarbonation unit, and anions are removed in the anion exchanger filling unit, thereby producing pure water.

[0003] However, cation exchangers and anion exchangers become saturated after a certain period of use and can no longer perform ion exchange, thus requiring regeneration. To completely regenerate saturated ion exchangers, large quantities of acid and alkali solutions are needed as regeneration solutions. Furthermore, the acid and alkali solutions used after regeneration are treated as waste liquid (regeneration waste liquid) and undergo neutralization. The neutralization of this waste liquid also uses large amounts of acid and alkali, leading to increased reagent usage and higher salt concentrations in the waste liquid. Therefore, from the perspectives of reducing reagent usage, lowering treatment costs, and mitigating environmental impact, it is also necessary to recycle the waste liquid (regeneration waste liquid).

[0004] In the above-mentioned recycling of waste liquid, it is required to remove high concentrations of waste acid and trace impurities in the waste alkaline solution, such as cations (potassium, sodium, calcium, magnesium, ammonium ions, etc.) or anions (chloride ions, sulfate ions, nitrate ions, etc.).

[0005] Electrodialysis is one method for ion removal, but a method has been proposed to treat regenerated wastewater using electrodialysis and recover the wastewater in the form of acids and alkalis.

[0006] For example, Patent Document 1 describes the following: In a treatment method in which the regeneration waste liquid generated in the regeneration process of an ion exchange resin using hydrochloric acid and sodium hydroxide is passed through an electrodialysis device to separate it into hydrochloric acid and sodium hydroxide, a membrane fouling agent with calcium precipitation inhibition effect, preventing calcium adhesion to the membrane, and preventing scale formation is added to the regeneration waste liquid.

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 11-566 Summary of the Invention The technical problem that the invention aims to solve However, the method described in Patent Document 1 requires the addition of membrane fouling prevention agent to the regenerated waste liquid, which increases the amount of reagent used and raises the cost.

[0008] On the other hand, in various factories, especially semiconductor factories, a large amount of waste acid is discharged from cleaning processes such as SPM cleaning (sulfuricacid-hydrogen peroxide mixture cleaning). In most cases, this waste acid is treated and discharged after neutralization. Therefore, it is hoped that such waste acid can be expanded to other uses.

[0009] The purpose of this invention is to provide an electrodialysis apparatus and method that can prevent scale formation on the ion exchange membrane surface of the electrodialysis apparatus and achieve stable acid recovery without cost, as well as a wastewater treatment apparatus equipped with the electrodialysis apparatus and a wastewater treatment method using the above-mentioned electrodialysis apparatus.

[0010] Technical solutions for solving technical problems The inventors conducted in-depth research on the above-mentioned issues and found that by using an electrodialysis device with a specific structure, acid can be efficiently recovered from waste liquid, thus completing the present invention.

[0011] The present invention includes the following methods.

[0012] [1] An electrodialysis apparatus, comprising at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are sequentially disposed. The above-mentioned electrodialysis device has the following features: The anode chamber is defined by the aforementioned anode and the aforementioned first bipolar membrane; The acid recovery chamber is defined by the aforementioned first bipolar membrane and the aforementioned anion exchange membrane; The desalination chamber is defined by the aforementioned anion exchange membrane and the aforementioned cation exchange membrane; The waste acid chamber is defined by the aforementioned cation exchange membrane and the aforementioned second bipolar membrane; and The cathode chamber is defined by the aforementioned second bipolar film and the aforementioned cathode. In the aforementioned electrodialysis apparatus, water is supplied to the acid recovery chamber, an acidic solution is supplied to the desalination chamber, and waste acid is supplied to the waste acid chamber for electrodialysis treatment.

[0013] [2] According to the electrodialysis apparatus described in [1], the waste acid mentioned above is waste acid discharged from a semiconductor factory.

[0014] [3] According to the electrodialysis apparatus described in [1] or [2], the acidic solution is the regeneration waste liquid of the cation exchanger.

[0015] [4] According to the electrodialysis apparatus described in [1] or [2], wherein the waste acid is an aqueous sulfuric acid solution and the sulfuric acid concentration of the waste acid is in the range of 1% to 20% by mass.

[0016] [5] The electrodialysis apparatus according to [1] or [2], wherein the electrodialysis apparatus comprises: The pH measuring unit measures the pH of the aforementioned waste acid. The pH of the waste acid measured by the pH measuring unit was less than 2 throughout the electrodialysis process.

[0017] [6] The electrodialysis apparatus according to [1] or [2], wherein the electrodialysis apparatus comprises: An acidic solution storage tank stores the acidic solution supplied to the desalination chamber. An acidic solution circulation path is provided, which returns the treated acidic solution discharged from the desalination chamber to the acidic solution storage tank and circulates it. An acidic solution circulation device that allows the acidic solution to circulate in the acidic solution storage tank and the acidic solution circulation path; The device is selected from at least one of a current measuring device, a conductivity measuring unit, and a pH measuring unit, wherein the current measuring device measures the current value between the anode and the cathode during electrodialysis treatment, the conductivity measuring unit measures the conductivity of the water or the acidic solution, and the pH measuring unit measures the pH of the water or the acidic solution; and A control device that controls the operation of the acidic solution circulation device and receives values ​​measured by at least one of the aforementioned current measuring device, conductivity measuring unit, and pH measuring unit. During electrodialysis, the control device uses the acidic solution circulation device to circulate the acidic solution. When at least one of the current slope, current, conductivity, and pH is within a specified range, the circulating acidic solution is replaced with the acidic solution outside the circulation system at a specified ratio or more, or discharged outside the circulation system.

[0018] [7] The electrodialysis apparatus according to [1] or [2], wherein the electrodialysis apparatus comprises: Nanofiltration device for separating the above-mentioned acidic solution into permeate and concentrate by passing it through a nanofiltration membrane; and Pipelines are used to supply the permeate to the desalination chamber.

[0019] [8] An electrodialysis method, characterized in that it is used to treat an acidic solution containing a hardness component. The above-mentioned electrodialysis method uses an electrodialysis device. The aforementioned electrodialysis apparatus includes at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are arranged sequentially. The above-mentioned electrodialysis device has the following features: The anode chamber is defined by the aforementioned anode and the aforementioned first bipolar membrane; The acid recovery chamber is defined by the aforementioned first bipolar membrane and the aforementioned anion exchange membrane; The desalination chamber is defined by the aforementioned anion exchange membrane and the aforementioned cation exchange membrane; The waste acid chamber is defined by the aforementioned cation exchange membrane and the aforementioned second bipolar membrane; and The cathode chamber is defined by the aforementioned second bipolar film and the aforementioned cathode. In the electrodialysis method: Water is supplied to the acid recovery chamber; The acidic solution is supplied to the desalination chamber; and Waste acid is supplied to the waste acid chamber for electrodialysis treatment.

[0020] [9] A waste liquid treatment device, characterized in that it comprises: A cation exchange device filled with cation exchangers; A regeneration solution storage tank, which stores the regeneration solution of the aforementioned cation exchanger; and An electrodialysis apparatus that treats the regeneration waste liquid discharged from the aforementioned cation exchange apparatus, which is supplied with the aforementioned regeneration solution. The aforementioned electrodialysis apparatus includes at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are arranged sequentially. The above-mentioned electrodialysis device has the following features: The anode chamber is defined by the aforementioned anode and the aforementioned first bipolar membrane; The acid recovery chamber is defined by the aforementioned first bipolar membrane and the aforementioned anion exchange membrane; The desalination chamber is defined by the aforementioned anion exchange membrane and the aforementioned cation exchange membrane; The waste acid chamber is defined by the aforementioned cation exchange membrane and the aforementioned second bipolar membrane; The cathode chamber is defined by the aforementioned second bipolar film and the aforementioned cathode; A unit that supplies water to the aforementioned acid recovery chamber; A unit that supplies acidic solution to the aforementioned desalination chamber; and The unit that supplies waste acid to the aforementioned waste acid chamber.

[0021]

[10] A waste liquid treatment method, comprising the following steps: The regeneration solution of the cation exchanger is supplied to the cation exchange apparatus filled with the cation exchanger; and The regenerated wastewater discharged from the aforementioned cation exchange unit is treated by electrodialysis. The above-mentioned electrodialysis treatment process uses an electrodialysis device. The aforementioned electrodialysis apparatus includes at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are arranged sequentially. The above-mentioned electrodialysis device has the following features: The anode chamber is defined by the aforementioned anode and the aforementioned first bipolar membrane; The acid recovery chamber is defined by the aforementioned first bipolar membrane and the aforementioned anion exchange membrane. The desalination chamber is defined by the aforementioned anion exchange membrane and the aforementioned cation exchange membrane; The waste acid chamber is defined by the aforementioned cation exchange membrane and the aforementioned second bipolar membrane; and The cathode chamber is defined by the aforementioned second bipolar film and the aforementioned cathode. The electrodialysis apparatus described above is used in the electrodialysis treatment process described above: Water is supplied to the acid recovery chamber described above; The aforementioned regenerated waste liquid is supplied to the aforementioned desalination chamber; and Waste acid is supplied to the aforementioned waste acid chamber for electrodialysis treatment.

[0022] Invention Effects According to the present invention, an electrodialysis apparatus and electrodialysis method, as well as a waste liquid treatment apparatus and waste liquid treatment method, can be provided that can prevent the formation of scale on the ion exchange membrane surface and can perform stable acid recovery without cost. Attached Figure Description

[0023] Figure 1 This is a schematic structural diagram illustrating an example of an electrodialysis apparatus according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic structural diagram illustrating another example of an electrodialysis apparatus according to an embodiment of the present invention.

[0025] Figure 3This is a schematic block diagram illustrating an example of a wastewater treatment apparatus for treating ion exchanger regeneration wastewater according to an embodiment of the present invention.

[0026] Figure 4 This is a schematic block diagram illustrating another example of a wastewater treatment apparatus for treating ion exchanger regeneration wastewater according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic block diagram illustrating another example of a wastewater treatment apparatus for treating ion exchanger regeneration wastewater according to an embodiment of the present invention.

[0028] Figure 6 It means that it was used Figure 2 The graph shows the relationship between conductivity and pH values ​​and operating time in the wastewater treatment of an embodiment of the electrodialysis apparatus.

[0029] Figure 7 It means that it was used Figure 2 The graph shows the relationship between current value and operating time in the wastewater treatment of an embodiment of the electrodialysis apparatus. Detailed Implementation

[0030] According to embodiments of the present invention, by using an electrodialysis device with a specific structure to perform electrodialysis of acidic solutions, scale formation can be prevented even without the use of chemicals, costs can be suppressed, and stable acid recovery can be achieved.

[0031] The electrodialysis apparatus according to embodiments of the present invention comprises at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane, and includes: an anode chamber defined by the anode and the first bipolar membrane; an acid recovery chamber defined by the first bipolar membrane and the anion exchange membrane; a desalination chamber defined by the anion exchange membrane and the cation exchange membrane; a waste acid chamber defined by the cation exchange membrane and the second bipolar membrane; and a cathode chamber defined by the second bipolar membrane and the cathode. In such an electrodialysis apparatus, water is supplied to the acid recovery chamber, an acidic solution is supplied to the desalination chamber, and waste acid is supplied to the waste acid chamber for electrodialysis treatment.

[0032] Na in the acidic solution supplied to the desalination chamber + When the cationic components move into the waste acid chamber, Cl - Move to the acid recovery chamber; at this point, H₂ is supplied to the acid recovery chamber from the bipolar membrane. + As a result, HCl can be recovered from the acid recovery chamber.

[0033] In addition, the Ca in the acidic solution supplied to the desalination chamber 2+ Mg 2+The hardness components move to the waste acid chamber. By controlling the pH of the waste acid (in the case of circulating waste acid, the addition and discharge of waste acid), scale formation can be prevented even without adding chemicals.

[0034] Furthermore, by determining the timing of the termination of electrodialysis treatment based on the pH, conductivity, and current value of the liquid being treated in each chamber, efficient electrodialysis can be achieved. Once the operating time of the electrodialysis unit has stabilized to a certain extent, electrodialysis can be terminated at that stable state.

[0035] Furthermore, the waste acid supplied to the waste acid chamber can be waste acid liquid discharged from various factories, effectively utilizing waste acid liquid discharged after neutralization treatment. For example, acid solutions used in factory manufacturing processes can be used; specifically, waste sulfuric acid generated in the SPM (sulfuric acid-hydrogen peroxide mixture cleaning) and SOM (sulfuric acid and ozone mixture) cleaning processes in semiconductor manufacturing can be used. By using such waste sulfuric acid, there is no need to prepare new reagents to deal with scale in the electrodialysis unit, reducing reagent costs and overall reagent usage.

[0036] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments and the structures shown in the drawings.

[0037] Figure 1 This illustrates an example of an electrodialysis apparatus according to one embodiment of the present invention. Figure 1 The electrodialysis apparatus 100 includes at least an anode 1, a cathode 17, a first bipolar membrane (hereinafter also referred to as "first BPM") 3, an anion exchange membrane (hereinafter also referred to as "AEM") 5, a cation exchange membrane (hereinafter also referred to as "CEM") 7, and a second bipolar membrane 9 (hereinafter also referred to as "second BPM"). Between the anode 1 and the cathode 17, the first BPM 3, AEM 5, CEM 7, and second BPM 9 are arranged sequentially from the anode 1 side. The structure includes: an anode chamber 20 defined by the anode 1 and the first BPM 3; an acid recovery chamber 22 defined by the first BPM 3 and AEM 5; a desalination chamber 24 defined by AEM 5 and CEM 7; a waste acid chamber 26 defined by CEM 7 and the second BPM 9; and a cathode chamber 34 defined by the second BPM 9 and the cathode 17.

[0038] Here, the anode chamber 20 houses the anode 1 and is provided with an acid recovery chamber 22 adjacent to the anode chamber 20 via a first BPM3. In addition, the cathode chamber 34 houses the cathode 17 and is provided with a waste acid chamber 26 adjacent to the cathode chamber 34 via a second BPM9.

[0039] In the above structure, the anode chamber 20 and the acid recovery chamber 22 are separated by a first BPM3, and the acid recovery chamber 22 and the desalination chamber 24 are separated by an AEM5. Furthermore, the desalination chamber 24 and the waste acid chamber 26 are separated by a CEM7, and the waste acid chamber 26 and the cathode chamber 34 are separated by a second BPM9. That is, Figure 1 The electrodialysis device 100 shown is a three-chamber electrodialysis device. The three-chamber electrodialysis device is arranged sequentially from the anode 1 side with a first BPM3, AEM5, CEM7 and a second BPM9, and the main structure consists of three chambers: acid recovery chamber 22, desalination chamber 24 and waste acid chamber 26.

[0040] Here, if we represent the chambers constituting the electrodialysis apparatus 100 sequentially from the anode 1 side, it becomes: anode - anode chamber - (acid recovery chamber - desalination chamber - waste acid chamber) n - cathode chamber - cathode. Here, the smallest repeating unit within the brackets "acid recovery chamber - desalination chamber - waste acid chamber" is taken as the basic structure (i.e., a unit group), and n (where n is an integer greater than or equal to 1) is the number of repeating layers in the unit group. It should be noted that in... Figure 1 The structure representing n=1 will be discussed later. Figure 2 The structure represents n=2.

[0041] The number of repetitions in a unit group can usually be set to the range of n = 1 to 500, preferably the range of 1 to 200.

[0042] If we represent the membranes constituting the electrodialysis apparatus 100 sequentially from the anode side, it becomes anode-BPM (AEM-CEM-BPM)n-cathode. Here, n (where n is an integer greater than or equal to 1) is also the number of repeated layers in the unit group. It should be noted that in Figure 1 The structure for n=1 is shown below, and will be discussed later. Figure 2 The structure for n=2 is shown in the figure.

[0043] exist Figure 1 In the electrodialysis apparatus 100 according to the embodiment of the present invention shown, pure water is supplied to the acid recovery chamber 22, an acidic solution is supplied to the desalination chamber 24, and waste acid is supplied to the waste acid chamber 26 for electrodialysis treatment. The pure water supplied to the acid recovery chamber 22 is discharged as recovered acid solution after passing through the acid recovery chamber 22. The acidic solution supplied to the desalination chamber 24 is discharged as desalinated water after passing through the desalination chamber 24. The waste acid supplied to the waste acid chamber 26 is discharged as treated waste acid after passing through the waste acid chamber 26. The pure water supplied to the acid recovery chamber 22 is only required to be water with low impurities and high purity that can perform the desired level of electrodialysis; water with a purity of reverse osmosis membrane treatment water or higher is preferred.

[0044] Bipolar membranes 3 and 9 are membranes that integrate a cation exchange membrane and an anion exchange membrane, typically having a structure in which the cation exchange membrane and anion exchange membrane overlap. Furthermore, the bipolar membrane has a structure in which the interface between the overlapping cation exchange membrane and anion exchange membrane is optimal for water dissociation reactions, and is configured to facilitate water dissociation reactions. For this purpose, substances with catalytic activity for water dissociation (e.g., heavy metal ions, tertiary amines, etc.) are typically introduced into the interface formed by overlapping the separate ion exchange membranes. Additionally, the bipolar membrane is configured with the anion exchange membrane side as the anode side and the cation exchange membrane side as the cathode side.

[0045] In addition, bipolar membranes 3 and 9 can be any membrane that is effective in water dissociation, not just membranes for sale as products, as long as they are structures formed by overlapping cation exchange membranes and anion exchange membranes.

[0046] The materials of the ion exchange membranes 5 and 7 used in the embodiments of the present invention are not particularly limited, and any known materials can be used, as long as the membrane is effective for salt separation. For example, a homogeneous membrane can be formed by coating a paste containing styrene and divinylbenzene with polyvinyl chloride, heating it, and then introducing the exchange groups; or a heterogeneous membrane can be formed by molding ion exchange resin powder using a suitable film-forming adhesive, such as polyethylene, polystyrene, phenolic resin, or synthetic rubber.

[0047] The anode 1 and cathode 17 can be electrodes used in electrochemical industries such as water electrolysis, and such electrodes can be used without any restrictions. Examples of electrodes that can be used for the anode 1 and cathode 17 include nickel electrodes, titanium-based platinum-plated electrodes, and stainless steel electrodes.

[0048] The anode and cathode chambers are each filled with an electrode solution. Examples of electrode solutions include sodium hydroxide solution, sodium sulfate solution, and pure water.

[0049] then, Figure 2 This illustrates another example of an electrodialysis apparatus according to an embodiment of the present invention. Figure 2 In the electrodialysis apparatus 200 shown, starting from the anode 1 side, anode 1, cathode 17, and BPM3 (equivalent to Figure 1 The first BPM in the system), AEM5 (equivalent to Figure 1 AEM5 and CEM7 (equivalent to) Figure 1 CEM7 and BPM11 (equivalent to CEM7) Figure 1 The second BPM9), AEM13, CEM15 and BPM9 (equivalent to Figure 1The second BPM9 in the structure comprises: an anode chamber 20, defined by anode 1 and BPM3; an acid recovery chamber 22, defined by BPM3 and AEM5; a desalination chamber 24, defined by AEM5 and CEM7; a waste acid chamber 26, defined by CEM7 and BPM11; an acid recovery chamber 28, defined by BPM11 and AEM13; a desalination chamber 30, defined by AEM13 and CEM15; a waste acid chamber 32, defined by CEM15 and BPM9; and a cathode chamber 34, defined by BPM9 and cathode 17. It should be noted that... Figure 2 It shows Figure 1 The structure of unit group n=2 in the text.

[0050] Pure water is supplied in parallel from the pure water tank to each acid recovery chamber (e.g., a circulation line from pure water tank to acid recovery chamber 22 to pure water tank, and a circulation line from pure water tank to acid recovery chamber 28 to pure water tank). This pure water only needs to be water with low impurities and high purity that can perform the desired level of electrodialysis, preferably water with a purity of more than that of water treated by reverse osmosis membrane.

[0051] An acidic solution, which is the liquid being treated, is supplied in parallel to each desalination chamber (e.g., a circulation line from the regeneration waste liquid storage tank to the desalination chamber 24 and then to the regeneration waste liquid storage tank, and a circulation line from the regeneration waste liquid storage tank to the desalination chamber 30 and then to the regeneration waste liquid storage tank). The acidic solution can be the cation exchanger regeneration waste liquid. For example, the regeneration waste liquid obtained in the regeneration of a cation exchanger packed tower using hydrochloric acid contains NaCl, KCl, CaCl2, MgCl2, and HCl produced through the ion exchange reaction. It should be noted that the acid used for the regeneration of the cation exchanger is not limited to hydrochloric acid; strong acids (inorganic acids) such as sulfuric acid and nitric acid can also be used in addition to hydrochloric acid.

[0052] Waste acid is supplied in parallel from the waste acid storage tank to each waste acid chamber (e.g., a circulation line from waste acid storage tank → waste acid chamber 26 → waste acid storage tank, and a circulation line from waste acid storage tank → waste acid chamber 32 → waste acid storage tank). In this case, it is preferable that the pH of the solution in the waste acid chamber is less than 2, more preferably less than 1. As the waste acid, for example, acid solutions used in the manufacturing processes of a factory can be used; specifically, waste sulfuric acid generated in the SPM (sulfuric acid-hydrogen peroxide mixture cleaning) or SOM (sulfuric acid and Ozone Mixture) cleaning processes in semiconductor manufacturing can be used. By using such waste sulfuric acid, there is no need to prepare new reagents to deal with scale buildup in the electrodialysis unit, thus reducing reagent costs and overall reagent usage.

[0053] The preferred sulfuric acid concentration for waste sulfuric acid is in the range of 1% to 20% by mass, and more preferably in the range of 1% to 10% by mass. By setting the sulfuric acid concentration to 1% by mass or more, the rise in pH can be effectively suppressed, and by setting it to 20% by mass or less, the deterioration of components can be prevented.

[0054] In addition, the hardness of the waste acid is preferably less than 1 ppm. This hardness is obtained by converting the total amount of calcium and magnesium into the amount of calcium carbonate (CaCO3).

[0055] It should be noted that the supply of waste acid can be either a single pass or a recycling process.

[0056] During electrodialysis operation, it is preferable to adjust the waste acid concentration or flow rate so that the pH of the waste acid in the waste acid chamber is less than 2 (preferably ≤ pH 1) throughout the entire operation. By keeping the pH of the waste acid in the waste acid chamber less than 2, scale formation during electrodialysis operation can be avoided, thereby preventing membrane damage and achieving stable operation. Furthermore, in the case of circulating waste acid, it is preferable to add and remove the waste acid intermittently. This not only ensures that the pH of the waste acid in the waste acid chamber is less than 2, but also allows impurities accumulated in the waste acid (hardness components, etc.) to be discharged from the system, preventing excessive increases in impurity concentration.

[0057] The following is about Figure 1 The movement of ions during electrodialysis in the electrodialysis apparatus shown is illustrated. It should be noted that although an example using hydrochloric acid as the acid for cation exchanger regeneration is shown, the same behavior will be observed when using acids other than hydrochloric acid.

[0058] At the overlapping interface of the cation exchange membrane and anion exchange membrane in the bipolar membrane (first BPM3 and second BPM9), H2O is converted to H+ via a water dissociation reaction. + and OH - In each electrode chamber, such as Figure 1 As shown, OH groups dissociated from the first BPM3 - H is supplied to the anode chamber 20 and dissociated by the second BPM9. + It is supplied to the cathode chamber 34. Therefore, when the same electrode solution is used in the anode chamber 20 and the cathode chamber 34, for example, by circulating the electrode solution between the anode chamber 20 and the cathode chamber 34, the supplied H can be made more efficient. + and OH - balance.

[0059] In acid recovery chamber 22, such as Figure 1 As shown, H is supplied from the first BPM3 dissociated from the anode side. + And Cl - It moves from desalination chamber 24 through AEM5. As a result, H + With Cl- They combine to form hydrochloric acid (HCl), which is then discharged outdoors.

[0060] In desalination chamber 24, such as Figure 1 As shown, Cl - AEM5 moves through the anode side to acid recovery chamber 22, Na + K + Ca 2+ Mg 2+ The solution moves through CEM7 on the cathode side to the waste acid chamber 26. Demineralized water is then generated from the acidic solution. The cation exchanger regeneration waste liquid (the treated liquid), which is supplied as the acidic solution, is then discharged outdoors as demineralized water after electrodialysis.

[0061] In waste acid chamber 26, such as Figure 1 As shown, Na + K + Ca 2+ Mg 2+ CEM7, passing through the anode side, moves from desalination chamber 24, and OH... - The waste acid is supplied from the cathode side of BPM9. In this way, the supplied waste acid is discharged outdoors as treated waste acid after electrodialysis.

[0062] Regarding the anode chamber 20 and the cathode chamber 34, although not shown in the figures, it is preferable to use an electrode liquid storage tank and a pump to circulate the electrode liquid between the electrode liquid storage tank, the anode chamber 20, and the cathode chamber 34. The electrode liquid can flow to the anode chamber and the cathode chamber in separate parallel circulation lines (electrode liquid storage tank → anode chamber → electrode liquid storage tank, electrode liquid storage tank → cathode chamber → electrode liquid storage tank), or it can flow in a single circulation line (electrode liquid storage tank → anode chamber → cathode chamber → electrode liquid storage tank, or electrode liquid storage tank → cathode chamber → anode chamber → electrode liquid storage tank).

[0063] Figure 3 This is a schematic block diagram illustrating an example of a wastewater treatment apparatus for treating ion exchanger regeneration wastewater according to an embodiment of the present invention. Pumps, valves, etc., are not shown.

[0064] The supply of various liquids (electrolyte, acidic solution (ion exchanger regeneration waste liquid), pure water, and waste acid) to the electrodialysis unit is achieved by pumping through various pipelines (flow paths) leading to each chamber (anode chamber, acid recovery chamber, desalination chamber, waste acid chamber, and cathode chamber).

[0065] exist Figure 3 In this configuration, a cation exchanger packed tower filled with cation exchangers is located downstream of an acid tank (regeneration solution storage tank). This acid tank stores acid for the regeneration of the aforementioned cation exchangers.

[0066] like Figure 3 As shown, a regeneration waste liquid storage tank is provided downstream of the aforementioned cation exchanger packed tower. The acid solution from the aforementioned cation exchanger packed tower is stored in the regeneration waste liquid in the regeneration waste liquid for the purpose of regenerating the aforementioned cation exchanger.

[0067] The preferred regeneration wastewater is that from cation exchangers used in the production of pure water in semiconductor plants. The regeneration wastewater from cation exchangers used in the production of pure water in semiconductor plants has low organic content and a low risk of organic pollution; therefore, by inhibiting scale buildup, the electrodialysis unit can operate stably.

[0068] like Figure 3 As shown, the electrodialysis unit is connected to the regeneration waste liquid storage tank. The cation exchanger regeneration waste liquid (acidic solution) supplied to the electrodialysis unit is as described above. Figure 1 As shown, the wastewater is supplied to the desalination chamber of the electrodialysis unit. After treatment in the desalination chamber, the regenerated wastewater (deionized water) is returned to the regenerated wastewater storage tank for recycling.

[0069] Such a recycling process can be performed by a circulation device that supplies regenerated waste liquid (acidic solution) from the regenerated waste liquid storage tank to the desalination chamber of the electrodialysis unit, and then returns it from the desalination chamber to the regenerated waste liquid storage tank for circulation. The regenerated waste liquid can be supplied using a pump. This circulation device can be configured such that if electrodialysis is terminated according to the endpoint determination described later, the recycled regenerated waste liquid (deionized water) is discharged from the regenerated waste liquid storage tank and discharged outside the system. The discharge destination for the deionized water can be, for example, combined with existing wastewater recovery equipment or wastewater treatment equipment. Alternatively, this circulation device can be configured to supply new regenerated waste liquid to the regenerated waste liquid storage tank after or simultaneously with the discharge of the recycled regenerated waste liquid (deionized water), thus enabling waste liquid replacement. Alternatively, it can be configured to discharge a portion (a predetermined proportion or more) of the recycled regenerated waste liquid, and supply new regenerated waste liquid to the regenerated waste liquid storage tank in proportion to the amount discharged. That is, a portion (or more than a specified proportion) of the recycled waste liquid after recycling can be replaced by new recycled waste liquid. The discharge of recycled waste liquid after recycling can be controlled by opening and closing a control valve installed on a discharge pipeline connected to the recycled waste liquid storage tank. The supply of new recycled waste liquid to the recycled waste liquid storage tank can be controlled by opening and closing a control valve installed on a supply pipeline connected to the recycled waste liquid storage tank.

[0070] like Figure 3 As shown, the pure water tank is connected to the electrodialysis unit. The pure water tank stores pure water (any water with low impurities and high purity is acceptable, preferably water with a purity higher than that of water treated by the reverse osmosis membrane). As described above, Figure 1As shown, pure water is supplied to the acid recovery chamber of the electrodialysis unit.

[0071] The treated pure water (recovered acid solution) after passing through the electrodialysis unit is returned to the pure water tank for recycling. If the electrodialysis is terminated by the endpoint determination described later, the recycled pure water (recovered acid solution) is transferred from the pure water tank to the acid solution tank, and pure water is re-supplyed to the pure water tank to replace the transferred recovered acid solution.

[0072] The acid solution in the acid tank is not only the recovered acid solution transferred from the pure water tank, but can also be supplemented from outside the system as needed and mixed with the recovered acid solution transferred from the pure water tank. After adjusting the concentration, it can be used. The pure water tank and the acid tank can also share the same tank. There is no particular limitation on the acid concentration of the acid solution in the acid tank, but for efficient regeneration of the ion exchanger, 1% to 10% by mass is preferred, and more preferably 1% to 5% by mass.

[0073] like Figure 3 As shown, the waste acid storage tank is connected to the electrodialysis unit. The waste acid storage tank stores waste acid (<pH2, preferably ≤pH1). As described above, as... Figure 1 As shown, the waste acid supplied to the electrodialysis unit is fed into the waste acid chamber of the electrodialysis unit.

[0074] The treated waste acid (treated waste acid) after passing through the electrodialysis unit is returned to the waste acid storage tank for recycling. During the electrodialysis process, it is preferable to monitor the pH of the liquid in the waste acid storage tank and appropriately discharge the recycled waste acid from the system and add new waste acid (i.e., preferably replace part of the recycled waste acid with new waste acid) so that the pH is less than 2 (preferably ≤ pH 1).

[0075] When electrodialysis is terminated based on the endpoint determination described later, the recycled waste acid (treated waste acid) can be discharged from the waste acid storage tank and replaced with new waste acid. The destination for discharging the treated waste acid can be, for example, merging with existing wastewater treatment or recycling equipment.

[0076] The volumes of liquids during circulation do not have to be equal; any water volume can be set according to the desired concentration of the recovered acid obtained from the acid recovery chamber. For example, compared to circulating pure water and regenerated waste liquid in equal volumes, reducing the circulation volume of pure water compared to the regenerated waste liquid will result in a higher concentration of recovered acid (conversely, increasing the circulation volume of pure water compared to the regenerated waste liquid will result in a lower concentration of recovered acid). However, reducing the volume of waste acid will lead to an increase in the hardness component, Ca. 2+ Mg 2+ It is highly concentrated, so caution is needed.

[0077] The operation of an electrodialysis unit can be intermittent, with each regeneration treatment of the ion exchanger; for example, it can also be as follows: Figure 3 The regenerated waste liquid storage tank is set up for continuous operation. In continuous operation, the endpoint of the electrodialysis treatment of the regenerated waste liquid (the start of discharge of the treated regenerated waste liquid) is aligned with the timing of the next cation exchanger regeneration (the start of supplying new regenerated waste liquid). Compared to intermittent operation, continuous operation allows for miniaturization of the electrodialysis unit, and the timing can be adjusted by reducing the supply flow rate of the regenerated waste liquid. Therefore, it is expected to achieve miniaturization of the electrodialysis unit, shorten start-up time, and stabilize the quality of the treated water.

[0078] Methods for determining the endpoint of electrodialysis treatment include: operating at a predetermined time; observing and determining the change in the current value flowing between the anode and cathode; observing and determining the change in the conductivity of pure water supplied to the acid recovery chamber or regenerated waste liquid (demineralized water) treated in the desalination chamber (applicable to cases where pure water or regenerated waste liquid is circulated); observing and determining the change in pH of pure water (recovered acid) treated in the acid recovery chamber or regenerated waste liquid (demineralized water) treated in the desalination chamber, and waste acid (treated waste acid) treated in the waste acid chamber (applicable to cases where the respective solutions are circulated).

[0079] If only a preset time is required, any time can be set, for example, to coincide with the timing of ion exchanger regeneration.

[0080] In the method of observing and determining changes in current value, a current measuring device is connected in series with the electrodialysis unit and the power supply unit, and the current value is sent to the control unit at predetermined intervals. If electrodialysis begins, the current value gradually increases, then decreases at a certain point, and then stabilizes at a relatively low value. Electrodialysis ends when the current value stabilizes at a relatively low level, i.e., when the current value remains within a predetermined range for a predetermined time. Whether the current value remains within the predetermined range for a predetermined time can be determined, for example, by whether the slope of the change in current value falls within the predetermined range.

[0081] In the method of observing and determining changes in conductivity, conductivity meters (conductivity measurement units) are installed at the outlets of each chamber, in the regenerated waste liquid storage tank, or in the pure water tank. Values ​​are sent to the control device at predetermined intervals. Electrodialysis is terminated when the conductivity reaches a predetermined value (range) or when the slope of the change is within a predetermined range. For example, regarding the trend of conductivity changes, as mentioned above, the conductivity of the pure water in the pure water tank gradually increases due to the influence of hydrochloric acid formation, and stabilizes at a high value after a certain period of time. Similarly, as mentioned above, the conductivity of the cation exchanger regenerated waste liquid in the regenerated waste liquid storage tank gradually decreases due to the movement of ions to the chamber adjacent to the desalination chamber, and stabilizes at a low value after a certain period of time.

[0082] In the method of observing and determining pH changes, pH meters (pH measurement units) are installed at the outlets of each chamber, in the regenerated waste liquid storage tank, in the pure water tank, or in the waste acid storage tank. Values ​​are sent to the control device at predetermined intervals. Electrodialysis is terminated when the pH reaches a predetermined value (range) or when the slope of the change is within a predetermined range. For example, regarding the tendency of pH changes, as mentioned above, the pH of the pure water in the pure water tank gradually decreases from near neutral due to the influence of hydrochloric acid formation, and stabilizes at a low value after a certain period of time. Similarly, as mentioned above, the pH of the cation exchange regenerated waste liquid in the regenerated waste liquid storage tank gradually increases from the acidic side due to the movement of ions to the chamber adjacent to the desalination chamber, and stabilizes at a side closer to neutral than the initial value after a certain period of time. Regarding the waste acid in the waste acid storage tank, as mentioned above, ions move from the adjacent desalination chamber and OH- is supplied from the bipolar membrane. - Due to the influence of [the environment / condition], its pH gradually increases from the acidic side.

[0083] Figure 4 This is a schematic block diagram illustrating another example of a wastewater treatment apparatus for treating ion exchanger regeneration wastewater according to an embodiment of the present invention. Pumps, valves, etc., are not shown.

[0084] Figure 4 The device shown is in Figure 3 The apparatus shown has a nanofiltration membrane (NF) structure between the cation exchanger packed tower and the regeneration waste liquid storage tank. Through this structure, the cation exchanger regeneration waste liquid that has passed through the NF is supplied to the regeneration waste liquid storage tank.

[0085] NF does not make Mg 2+ Ca 2+ Such divalent ions permeate, allowing Cl to pass through. - Na + Monovalent ions can pass through. As a result, in downstream electrodialysis equipment, it is possible to further prevent the accumulation of hardness components and the formation of scale on the membrane surface.

[0086] Figure 5This is a schematic block diagram showing another example of a waste liquid treatment device for treating the regeneration waste liquid of an ion exchanger according to an embodiment of the present invention. Pumps, valves, etc. are not shown.

[0087] In the Figure 5 shown device, compared with the Figure 3 structure, the desalted water (treated regeneration waste liquid) discharged from the electrodialysis device does not circulate back to the regeneration waste liquid storage tank but is directly discharged out of the system. In addition, compared with the Figure 3 structure, the recovered acid solution discharged from the electrodialysis device does not circulate back to the pure water tank but is directly transferred to the acid solution tank. In addition, compared with the Figure 3 structure, the treated waste acid discharged from the electrodialysis device does not circulate back to the waste acid storage tank but is directly discharged out of the system.

[0088] By setting it to the Figure 5 device structure, at the end of electrodialysis, there is no need to replace the solution in each tank. The regeneration waste liquid is supplied in each regeneration treatment of the cation exchanger, and pure water and waste acid equal to the discharge amount of each liquid are respectively supplied to the electrodialysis device during electrodialysis operation. In addition, for the waste acid (<pH2, preferably ≤pH1), there is no need to monitor the pH, so the operation can be simplified. Further, by making the supply flow rate and discharge flow rate of each solution the same, it is not necessarily required to provide each tank for the pure water tank and the waste acid storage tank.

[0089] It should be noted that part of the structure of the Figure 5 shown structure is set as shown in Figure 3 For example, it can be the following structure: The recovered acid solution (treated pure water) and desalted water (treated regeneration waste liquid) discharged from the electrodialysis device are circulated, while the treated waste acid is not circulated and is directly discharged. In order to achieve miniaturization of the electrodialysis device and stable treated water quality, it is preferable to circulate the recovered acid solution (treated pure water) and desalted water (treated regeneration waste liquid).

[0090] When the desalted water (treated regeneration waste liquid) is not circulated and is directly discharged, the operation method of the electrodialysis device can be the same as the case where the desalted water (treated regeneration waste liquid) is circulated. It can be intermittent operation for each regeneration treatment of the ion exchanger, or can also be set to continuous operation. When set to continuous operation, it is only necessary to overlap the timing of the end of electrodialysis treatment with the timing of regeneration of the ion exchanger (start of supply of regeneration waste liquid). Compared with intermittent operation, continuous operation miniaturizes the electrodialysis device, and it is only necessary to reduce the supply flow rate of the regeneration waste liquid and adjust the timing. Thus, miniaturization of the electrodialysis device, shortening of the startup time, and stabilization of the treated water quality can be expected.

[0091] When changing the Figure 5In the structure shown, where the recovered acid solution (treated pure water) is discharged directly without being circulated, the endpoint of the electrodialysis treatment is the point at which the regenerated waste liquid is exhausted.

[0092] In change Figure 5 In the structure shown, where the recycled acid solution (treated pure water) is circulated to the pure water tank, the endpoint of the electrodialysis treatment can be determined using the conductivity, pH, operating time, and current value of the pure water tank, in addition to the point when the regenerated waste liquid is exhausted.

[0093] In change Figure 5 In the structure shown, where the deionized water (treated regenerated waste liquid) is circulated and the recovered acid (treated pure water) is discharged directly without circulation, the endpoint of the electrodialysis treatment can be determined using the conductivity, pH, operating time, and current value of the aforementioned regenerated waste liquid storage tank.

[0094] In water treatment processes involving acidic wastewater from pure water production, semiconductor manufacturing, and other sources, by applying a wastewater recovery device equipped with the electrodialysis apparatus according to embodiments of the present invention, scale formation on the ion exchange membrane surface can be avoided even without adding anti-scaling chemicals, enabling stable acid recovery based on the electrodialysis apparatus at no cost. Furthermore, since scale formation on the ion exchange membrane surface can be prevented, membrane damage to the electrodialysis apparatus can be prevented, allowing for stable and efficient operation.

[0095] Example The following examples illustrate the present invention, but the present invention is not limited to the following examples.

[0096] (Example 1) In this embodiment, according to the use Figure 2 The embodiment of the electrodialysis apparatus shown in this invention performs electrodialysis treatment under the following implementation conditions. Additionally, a storage tank for the supply liquid to each chamber is provided for circulation processing.

[0097] (Experimental conditions) • Experimental setup: Bipolar membrane electrodialysis system manufactured by Astom (product name: Acilyzer EX3B) • Water quality of the supply solution: as recorded in Table 1 • Supply liquid to the desalination chamber: Regeneration waste liquid from the cation exchange packed tower used in pure water production. • Supply solution to the waste acid chamber: approximately 8% sulfuric acid by mass • Supply solution to the acid recovery chamber: pure water (reverse osmosis membrane treated water) Electrode solution: 4% NaOH (by mass) Water temperature: 20℃~25℃ (room temperature) • Supply liquid volume and circulation flow rate to the desalination chamber: 850 mL, 1.4 L / min • Supply and circulation flow rate to the waste acid chamber: 850 mL, 1.4 L / min • Supply and circulation flow rates for the acid recovery chamber: 850 mL, 1.4 L / min • Voltage: 10V (constant) pH was measured using a portable pH meter (product name: HM-40P) manufactured by Toa DKK Corporation (glass electrode method) to determine the pH of each supply solution in the tank.

[0098] The conductivity was measured using a conductivity meter (product name: AOL-10) manufactured by Toa DKK Corporation to measure the conductivity of each supply liquid in the tank.

[0099] The determination of ions in liquids was performed using an ion chromatograph (product name: Dionex Integrion) manufactured by Thermo Fisher Scientific Co., Ltd.

[0100] (Experimental Results) The conductivity and pH changes (as of operating time) of the regenerated wastewater (deionized water) supplied and treated to the desalination chamber and the pure water (recovered acid) supplied and treated to the acid recovery chamber are shown in the figure. Figure 6 The shift in the current value of the electrodialysis unit (the change in value over time) is shown in... Figure 7 The shifts in water quality for each supplied solution are shown in Table 1.

[0101] As shown in Table 1, electrodialysis can confirm the presence of Na in the desalination chamber. + When the cationic components move into the waste acid chamber, Cl - Move to the acid recovery chamber. It was also confirmed that 120 minutes after the start of electrodialysis, most of the Cl in the desalination chamber had been removed. - Move to the acid recovery chamber to recover HCl (recover acid solution).

[0102] In addition, through the above Figure 2 Ion movement in the apparatus shown (Table 1), such as Figure 6As shown, for the pure water (recovered acid solution) treated in the acid recovery chamber, its conductivity increases and stabilizes at a high value after about 90 minutes, while the pH starts near neutral and becomes pH < 1 after 40 minutes. Conversely, for the regenerated wastewater (desalinated water) treated in the desalination chamber, its conductivity decreases and stabilizes at a low value after about 90 minutes, while the pH starts around 1 and stabilizes at around pH 3.5 after about 100 minutes.

[0103] like Figure 7 As shown, if electrodialysis is started, the current flowing between the anode and cathode of the electrodialysis device increases significantly after about 10 minutes, then decreases after about 30 minutes, and then stabilizes at a low value after about 110 minutes.

[0104] As described above, in this embodiment, after approximately 110 minutes from the start of electrodialysis, the conductivity of the liquids in the desalination chamber and the acid recovery chamber is stable, and the current flowing between the anode and cathode of the electrodialysis device is also stable at a low value.

[0105] In addition, no decrease in current value caused by scale formation was found during electrodialysis, and scale material could not be visually observed on the ion exchange membrane surface after electrodialysis.

[0106] As can be seen from the above, according to the present invention, scale formation can be prevented, and acid can be stably recovered from the regenerated waste liquid without incurring costs.

[0107] [Table 1] (See Example 1 for reference) Sulfuric acid, adjusted to pH 3, was supplied as the feed liquid to the waste acid chamber. Otherwise, electrodialysis was performed in the same manner as in Example 1.

[0108] Compared to Example 1, a decrease in current value was confirmed (the peak current value was less than 2A, gradually decreasing throughout, eventually dropping to almost 0A after about 80 minutes). Additionally, a deterioration in the quality of the treated water was confirmed (Cl in the acid recovery chamber after 120 minutes from the start of electrodialysis). - (Concentration: 4000 mg / L). Furthermore, 120 minutes after the start of electrodialysis, upon inspection of the interior of the electrodialysis device, white scale was observed on the cation exchange membrane surface. This was attributed to the precipitate of components such as Ca(OH)₂ and Mg(OH)₂.

[0109] Explanation of reference numerals in the attached figures 1: Anode 3: First bipolar membrane (BPM) 5: First Anion Exchange Membrane (AEM) 7: First cation exchange membrane (CEM) 9: Second bipolar membrane (BPM) 11: Second bipolar membrane (BPM) 13: Second Anion Exchange Membrane (AEM) 15: Second cation exchange membrane (CEM) 17: Cathode 20: Anode Chamber 22: First Acid Recovery Chamber 24: First Desalination Chamber 26: First Waste Acid Chamber 28: Second Acid Recovery Chamber 30: Second Desalination Chamber 32: Second waste acid chamber 34: Cathode chamber.

Claims

1. An electrodialysis device, characterized in that, It has at least: an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane are sequentially disposed. The electrodialysis device has: The anode chamber is defined by the anode and the first bipolar film; The acid recovery chamber is defined by the first bipolar membrane and the anion exchange membrane; The desalination chamber is defined by the anion exchange membrane and the cation exchange membrane; The waste acid chamber is defined by the cation exchange membrane and the second bipolar membrane; as well as The cathode chamber is defined by the second bipolar film and the cathode. In the electrodialysis apparatus, water is supplied to the acid recovery chamber, an acidic solution is supplied to the desalination chamber, and waste acid is supplied to the waste acid chamber for electrodialysis treatment.

2. The electrodialysis apparatus according to claim 1, wherein, The waste acid is waste acid discharged from the semiconductor factory.

3. The electrodialysis apparatus according to claim 1 or 2, wherein, The acidic solution is the waste liquid from the regeneration of cation exchangers.

4. The electrodialysis apparatus according to claim 1 or 2, wherein, The waste acid is an aqueous solution of sulfuric acid, and the sulfuric acid concentration of the waste acid is in the range of 1% to 20% by mass.

5. The electrodialysis apparatus according to claim 1 or 2, wherein, The electrodialysis device has: The pH measuring unit measures the pH of the waste acid. The pH of the waste acid, as measured by the pH measuring unit, is less than 2 throughout the electrodialysis process.

6. The electrodialysis apparatus according to claim 1 or 2, wherein, The electrodialysis device has: An acidic solution storage tank stores the acidic solution supplied to the desalination chamber; An acidic solution circulation path that returns the treated acidic solution discharged from the desalination chamber to the acidic solution storage tank for circulation; An acidic solution circulation device that allows the acidic solution to circulate in the acidic solution storage tank and the acidic solution circulation path; The device is selected from at least one of a current measuring device, a conductivity measuring unit, and a pH measuring unit, wherein the current measuring device measures the current value between the anode and the cathode during electrodialysis treatment, the conductivity measuring unit measures the conductivity of the water or the acidic solution, and the pH measuring unit measures the pH of the water or the acidic solution. as well as A control device that controls the operation of the acidic solution circulation device and receives values ​​measured by at least one selected from the current measuring device, the conductivity measuring unit, and the pH measuring unit. During electrodialysis, the control device uses the acidic solution circulation device to circulate the acidic solution. When at least one of the current slope, current, conductivity, and pH is within a specified range, the circulating acidic solution is replaced with the acidic solution outside the circulation system at a specified ratio or more, or discharged outside the circulation system.

7. The electrodialysis apparatus according to claim 1 or 2, wherein, The electrodialysis device has: A nanofiltration device that separates the acidic solution into a permeate and a concentrate via a nanofiltration membrane; and Pipelines for supplying the permeate to the desalination chamber.

8. An electrodialysis method, characterized in that, Used for treating acidic solutions containing hardness components. The electrodialysis method uses an electrodialysis device. The electrodialysis device includes at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are arranged sequentially. The electrodialysis device has: The anode chamber is defined by the anode and the first bipolar film; The acid recovery chamber is defined by the first bipolar membrane and the anion exchange membrane; The desalination chamber is defined by the anion exchange membrane and the cation exchange membrane; The waste acid chamber is defined by the cation exchange membrane and the second bipolar membrane; as well as The cathode chamber is defined by the second bipolar film and the cathode. In the electrodialysis method: Water is supplied to the acid recovery chamber; The acidic solution is supplied to the desalination chamber; and Waste acid is supplied to the waste acid chamber for electrodialysis treatment.

9. A waste liquid treatment device, characterized in that, have: A cation exchange device filled with cation exchangers; A regeneration solution storage tank for storing the regeneration solution of the cation exchanger; and An electrodialysis apparatus for treating the regeneration waste liquid discharged from the cation exchange unit, which is supplied with the regeneration solution. The electrodialysis device includes at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are arranged sequentially. The electrodialysis device has: The anode chamber is defined by the anode and the first bipolar film; The acid recovery chamber is defined by the first bipolar membrane and the anion exchange membrane; The desalination chamber is defined by the anion exchange membrane and the cation exchange membrane; The waste acid chamber is defined by the cation exchange membrane and the second bipolar membrane; A cathode chamber, defined by the second bipolar film and the cathode; A unit that supplies water to the acid recovery chamber; A unit that supplies acidic solution to the desalination chamber; as well as A unit that supplies waste acid to the waste acid chamber.

10. A method for treating waste liquid, characterized in that, It has the following processes: Supplying a regeneration solution of the cation exchanger to a cation exchanger filled with the cation exchanger; and The regenerated wastewater discharged from the cation exchange unit is treated by electrodialysis. The electrodialysis treatment process uses an electrodialysis device. The electrodialysis device includes at least an anode, a cathode, a first bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a second bipolar membrane. Between the anode and the cathode, starting from the anode side, the first bipolar membrane, the anion exchange membrane, the cation exchange membrane, and the second bipolar membrane are arranged sequentially. The electrodialysis device has: The anode chamber is defined by the anode and the first bipolar film; The acid recovery chamber is defined by the first bipolar membrane and the anion exchange membrane; The desalination chamber is defined by the anion exchange membrane and the cation exchange membrane; The waste acid chamber is defined by the cation exchange membrane and the second bipolar membrane; as well as The cathode chamber, defined by the second bipolar membrane and the cathode, is used in the electrodialysis process of the electrodialysis apparatus. Water is supplied to the acid recovery chamber; The regenerated waste liquid is supplied to the desalination chamber; and Waste acid is supplied to the waste acid chamber for electrodialysis treatment.

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