Method for cleaning dirt blockage of electrodialyzer

Abstract

According to the method for cleaning dirt and blockage of the electrodialyzer, on the basis that the electrodialyzer is not disassembled and detected, microorganisms, organic dirt and blockage and inorganic dirt and blockage in the electrodialyzer are efficiently removed through the cooperation mode of circulating sterilization, alkali washing and acid washing, damage to a membrane is reduced, and the production cost is reduced. After the electrodialyzer is cleaned through the method, the water treatment amount, the flow speed and the ion migration efficiency of the electrodialyzer can be effectively recovered, and the designed flux is achieved; meanwhile, the temperature rise of the electrodialyzer can be delayed, the service cycle of the electrodialyzer is prolonged, and the energy consumption of the electrodialyzer is reduced. The method is suitable for cleaning organic sewage plugs and inorganic sewage plugs of heterogeneous membrane electrodialyzers, semi-homogeneous membrane electrodialyzers, homogeneous membrane electrodialyzers, bipolar membrane electrodialyzers and the like, and is wide in application range and high in decontamination efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of membrane cleaning and relates to a method for cleaning fouling of an electrodialyser. Background Art

[0002] Electrodialyzer is a device that uses ion exchange membranes and direct current electric fields to cause the selective migration of electrolyte ions in water, thereby achieving water desalination. It has the advantages of simple process, high desalination rate, and no pollution to the environment. It is mainly used for water desalination, chemical separation, concentration, and industrial wastewater treatment.

[0003] When an electrodialyzer is used for industrial wastewater treatment, a large amount of dirt will accumulate inside the electrodialyzer after a period of use, affecting its working efficiency. Therefore, the electrodialyzer needs to be cleaned regularly. At present, there are two main ways to clean the electrodialyzer. One is to use a flexible cotton cloth to wipe the cation membrane, anion membrane, polar membrane, partition, etc. one by one after disassembly and inspection to effectively remove inorganic and organic fouling, but it is time-consuming and labor-intensive, with low work efficiency and high cost; the second is to use acid-base chemical cleaning, but it only has a good removal effect on inorganic salt scaling.

[0004] When using acid-base chemical cleaning of the electrodialyzer, acid cleaning is usually the main method and alkaline cleaning is the auxiliary method. This is related to the fact that the ion exchange membrane of the electrodialyzer is not resistant to alkaline. Conventional alkaline cleaning cannot effectively remove organic matter, bacteria and algae attached to the screen, flow channel and diaphragm due to the limitations of short cleaning time and cleaning solution concentration, which restricts the recovery of diaphragm performance. Under the same power consumption conditions, the work efficiency is low. In addition, it will also lead to increased resistance and heat generation of the electrodialyzer, burnout of the electrodialyzer and shortened life. Summary of the invention

[0005] The purpose of the present invention is to provide a method for cleaning fouling of an electrodialyser, so as to solve the problem that the existing electrodialyser has poor cleaning and removal effect.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a method for cleaning fouling of an electrodialyser, comprising: S01: Use oxidizing disinfectant or sodium hypochlorite solution for cyclic sterilization.

[0007] When the electrodialyser is not disassembled for inspection, the electrodialyser is first sterilized by a bactericide to eliminate microorganisms in the electrodialyser and reduce microbial fouling. In the present application, an oxidizing bactericide or a sodium hypochlorite solution can be used to sterilize the electrodialyser by a bactericide.

[0008] When using an oxidizing bactericide to sterilize and clean the electrodialyzer, add an oxidizing bactericide with a mass concentration of 0.03-0.1% into the electrodialyzer, circulate the oxidizing bactericide in the electrodialyzer for 1-2 hours, and then soak for 1-2 hours; after soaking, the oxidizing bactericide continues to circulate in the electrodialyzer for 1 hour; finally, use clean water to completely replace the oxidizing bactericide in the electrodialyzer. The amount of clean water used is at least 3 times or more of the amount of oxidizing bactericide used.

[0009] In the present application, oxidizing fungicides include isothiazolinone fungicides and bromine oxidizing fungicides. Specifically, isothiazolinone fungicides include at least one of 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one. Bromine oxidizing fungicides include at least one of polybrominated compound fungicides, bromophenol fungicides and bromoamine fungicides.

[0010] When using sodium hypochlorite solution to sterilize and clean the electrodialyzer, fill the electrodialyzer with a sodium hypochlorite solution of 0.01-0.05% mass concentration, circulate the sodium hypochlorite solution in the electrodialyzer for 30-45 minutes, and finally use clean water to completely replace the sodium hypochlorite solution in the electrodialyzer. The amount of clean water used is at least 3 times or more of the amount of sodium hypochlorite solution used.

[0011] S02: When the hardness of the water source treated by the electrodialyser is greater than 20 mg / L, the electrodialyser is cleaned by acid washing, alkaline washing and acid washing in sequence.

[0012] After the cyclic sterilization treatment is completed, the electrodialyzer is further cleaned by a combination of acid washing and alkaline washing.

[0013] When the hardness of the water source treated by the electrodialysis unit is greater than 20 mg / L, the inorganic fouling on the anion and cation membranes is first removed by acid washing, and then the organic fouling on the anion and cation membranes and the separator is removed by alkaline washing. Finally, the flow channel of the electrodialysis membrane is shrunk by acid washing. The hardness of the treated water source is measured in terms of calcium carbonate.

[0014] Specifically, the pickling process is: Use industrial hydrochloric acid with a concentration of more than 30% to prepare a hydrochloric acid solution with a pH value of 2-3. Fill the hydrochloric acid solution into the electrodialyzer, circulate the hydrochloric acid solution in the electrodialyzer for 2-4 hours, and then soak for 1-2 hours. After soaking, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, use clean water to completely replace the hydrochloric acid solution in the electrodialyzer until the pH value is neutral.

[0015] The alkaline washing process is: Use caustic soda to prepare a caustic soda solution with a pH value of 11.5-13. Add chelating agent EDTA to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.5-1.0%. Add builder sodium tripolyphosphate to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. Fill the cleaning solution into the electrodialyzer, circulate the cleaning solution in the electrodialyzer for 2-4 hours, and then soak for 1-2 hours. After the soaking is completed, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, use clean water to completely replace the cleaning solution in the electrodialyzer until the pH value is neutral.

[0016] S03: When the hardness of the water source treated by the electrodialyser is ≤20mg / L, the electrodialyser is cleaned by alkaline washing and acid washing in sequence.

[0017] When the hardness of the water source treated by the electrodialyzer is ≤20mg / L, the organic contaminants on the anion and cation membranes and the separators are first removed by alkaline washing, and finally the inorganic contaminants on the anion and cation membranes are removed by acid washing, and the flow channel of the electrodialysis membrane is shrunk. The specific methods of alkaline washing and acid washing are the same as those when the hardness of the water source treated by the electrodialyzer is greater than 20mg / L.

[0018] The present invention has the following beneficial effects: (1) Without disassembling the electrodialyzer, the microorganisms, organic fouling and inorganic fouling in the electrodialyzer can be efficiently removed through the combination of cyclic sterilization, alkaline washing and acid washing, thereby reducing damage to the membrane and lowering production costs.

[0019] (2) This method can effectively restore the treated water volume, flow rate and ion migration efficiency of the electrodialyser to achieve the designed flux; at the same time, it can also delay the temperature rise of the electrodialyser, extend the service life of the electrodialyser, and reduce the energy consumption of the electrodialyser.

[0020] (3) Without increasing the acid and alkali concentrations, it can effectively remove inorganic and organic fouling and restore electrodialysis work.

[0021] (4) This method is suitable for cleaning organic and inorganic fouling in heterogeneous membrane electrodialyzers, semi-homogeneous membrane electrodialyzers, homogeneous membrane electrodialyzers, bipolar membrane electrodialyzers, etc. It has a wide range of applications and high decontamination efficiency. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0023] Example 1 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S101: Fill the electrodialyzer with an oxidizing bactericide with a mass concentration of 0.03%, and circulate the oxidizing bactericide in the electrodialyzer for 2 hours, and then soak for 2 hours; after soaking, the oxidizing bactericide continues to circulate in the electrodialyzer for 1 hour; finally, use clean water to completely replace the oxidizing bactericide in the electrodialyzer. The amount of clean water used is at least 3 times or more of the amount of oxidizing bactericide used.

[0024] S102: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is greater than 20 mg / L, the electrodialyzer is cleaned by acid washing, alkali washing, and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 2 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 2 hours, and then soaked for 1 hour. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 11.5 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.5%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 2 hours, and then soaked for 1 hour. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0025] Example 2 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S201: Add 0.1% oxidizing bactericide to the electrodialyzer, circulate the oxidizing bactericide in the electrodialyzer for 1 hour, and then soak for 1 hour; after soaking, the oxidizing bactericide continues to circulate in the electrodialyzer for 1 hour; finally, use clean water to completely replace the oxidizing bactericide in the electrodialyzer. The amount of clean water used is at least 3 times the amount of oxidizing bactericide used.

[0026] S202: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is greater than 20 mg / L, the electrodialyzer is cleaned by acid washing, alkali washing, and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 3 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 4 hours, and then soaked for 2 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 13 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 1.0%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 4 hours, and then soaked for 2 hours. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0027] Example 3 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S301: Fill the electrodialyzer with an oxidizing bactericide with a mass concentration of 0.03%, and circulate the oxidizing bactericide in the electrodialyzer for 1.5 hours, and then soak for 1.5 hours; after soaking, the oxidizing bactericide continues to circulate in the electrodialyzer for 1 hour; finally, use clean water to completely replace the oxidizing bactericide in the electrodialyzer. The amount of clean water used is at least 3 times or more of the amount of oxidizing bactericide used.

[0028] S302: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is ≤20mg / L, the electrodialyzer is cleaned by alkali washing and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 2.7 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 3 hours, and then soaked for 1.5 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 12 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.8%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 3 hours, and then soaked for 1.5 hours. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0029] Example 4 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S401: Fill the electrodialyzer with an oxidizing bactericide with a mass concentration of 0.05%, and circulate the oxidizing bactericide in the electrodialyzer for 2 hours, and then soak for 2 hours; after soaking, the oxidizing bactericide continues to circulate in the electrodialyzer for 1 hour; finally, use clean water to completely replace the oxidizing bactericide in the electrodialyzer. The amount of clean water used is at least 3 times or more of the amount of oxidizing bactericide used.

[0030] S402: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is ≤20mg / L, the electrodialyzer is cleaned by alkali washing and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 2.5 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 2.5 hours, and then soaked for 2 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 12.5 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.8%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 3 hours, and then soaked for 2 hours. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0031] Example 5 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S501: Sodium hypochlorite solution with a mass concentration of 0.05% is filled into the electrodialyzer, and the sodium hypochlorite solution is circulated in the electrodialyzer for 30 minutes, and finally the sodium hypochlorite solution in the electrodialyzer is completely replaced with clean water. The amount of clean water used is at least 3 times or more of the amount of sodium hypochlorite solution used.

[0032] S502: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is greater than 20 mg / L, the electrodialyzer is cleaned by acid washing, alkali washing, and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 2 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 4 hours, and then soaked for 1 hour. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 11.5 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.5%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer, and the cleaning solution is circulated in the electrodialyzer for 2 hours, and then soaked for 2 hours. After the soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0033] Example 6 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S601: Sodium hypochlorite solution with a mass concentration of 0.01% is filled into the electrodialyzer, and the sodium hypochlorite solution is circulated in the electrodialyzer for 45 minutes, and finally the sodium hypochlorite solution in the electrodialyzer is completely replaced with clean water. The amount of clean water used is at least 3 times or more of the amount of sodium hypochlorite solution used.

[0034] S602: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is greater than 20 mg / L, the electrodialyzer is cleaned by acid washing, alkali washing, and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 3 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 2 hours, and then soaked for 2 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 13 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.6%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 4 hours, and then soaked for 1 hour. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0035] Example 7 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S701: Sodium hypochlorite solution with a mass concentration of 0.01% is filled into the electrodialyzer, and the sodium hypochlorite solution is circulated in the electrodialyzer for 35 minutes, and finally the sodium hypochlorite solution in the electrodialyzer is completely replaced with clean water. The amount of clean water used is at least 3 times or more of the amount of sodium hypochlorite solution used.

[0036] S702: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is ≤20mg / L, the electrodialyzer is cleaned by alkali washing and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 2.8 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 3 hours, and then soaked for 1.5 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 12.3 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.8%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 3 hours, and then soaked for 1.5 hours. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0037] Example 8 The present invention provides a method for cleaning an electrodialyser fouling, the method comprising: S801: Sodium hypochlorite solution with a mass concentration of 0.05% is filled into the electrodialyzer, and the sodium hypochlorite solution is circulated in the electrodialyzer for 40 minutes, and finally the sodium hypochlorite solution in the electrodialyzer is completely replaced with clean water. The amount of clean water used is at least 3 times or more of the amount of sodium hypochlorite solution used.

[0038] S802: After the cyclic sterilization treatment is completed, when the hardness of the water source treated by the electrodialyzer is ≤20mg / L, the electrodialyzer is cleaned by alkali washing and acid washing in sequence. The acid washing process is as follows: a hydrochloric acid solution with a pH value of 2.2 is prepared using industrial hydrochloric acid with a concentration of more than 30%. The hydrochloric acid solution is filled into the electrodialyzer, and the hydrochloric acid solution is circulated in the electrodialyzer for 2.5 hours, and then soaked for 2 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours; finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. The alkali washing process is as follows: a caustic soda solution with a pH value of 12.8 is prepared using caustic soda. A complexing agent EDTA is added to the caustic soda solution to form a mixed solution, wherein the concentration of the mixed solution is 0.9%. A detergent sodium tripolyphosphate is added to the mixed solution to form a cleaning solution, wherein the concentration of the cleaning solution is 2%. The cleaning solution is loaded into the electrodialyzer and circulated in the electrodialyzer for 3.5 hours, and then soaked for 1 hour. After soaking, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; finally, the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0039] Application Examples In the comprehensive chemical park wastewater zero discharge project, the three-stage series mode of frequent reversal electrodialysis is designed to have a circulation volume of 24 cubic meters per hour for both fresh water and concentrated water. In summer, the inlet water temperature is high, the organic matter content of the inlet water is above 150 mg / L, and the water contains a small amount of flocculant, and the inlet water hardness (calculated as calcium carbonate) is 10 mg / L. After the water is distributed through the water distribution plate, the flow rate is reduced from 1.5 meters to 0.2 meters, and the organic matter adheres to the fine flow channels of the partition and the membrane surface. After long-term operation of frequent reversal electrodialysis, floccules are formed in the flow channels of the partition, blocking the flow channels and the membrane channels, causing the circulation water volume to be reduced to 18 cubic meters per hour, the operating voltage is 280V, and the currents are 90A, 45A, and 32A respectively. Due to the serious fouling, the oxidizing disinfectant + alkali washing + acid washing method is used for cleaning.

[0040] Specifically, in the first step, after the frequent polarity reversal electrodialysis is circulated for 45 minutes using a sodium hypochlorite solution with a mass concentration of 0.05%, the sodium hypochlorite solution in the electrodialyzer is completely replaced with clean water. In the second step, a caustic soda solution with a pH of 13 is prepared, and the complexing agent EDTA and the detergent sodium tripolyphosphate are added to form a cleaning solution. The prepared cleaning solution is used to circulate the frequent polarity reversal electrodialysis for 3 hours and soak for 2 hours. After the soaking is completed, the cleaning solution continues to circulate in the electrodialyzer for 2 hours; the cleaning solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral. In the third step, a hydrochloric acid solution with a pH value of 2.5 is used to circulate in the frequent polarity reversal electrodialysis for 3 hours and soak for 2 hours. After the soaking is completed, the hydrochloric acid solution continues to circulate in the electrodialyzer for 2 hours to shrink the membrane pores. Finally, the hydrochloric acid solution in the electrodialyzer is completely replaced with clean water until the pH value is neutral.

[0041] After cleaning, the circulation volume of fresh water and concentrated water in the frequent reversal electrodialysis was restored to 24 cubic meters per hour. At the same time, under the same voltage of 280V, the electrodialysis operating current was 102A, 56A, and 38A.

[0042] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for cleaning fouling of an electrodialyser, characterized in that: include: Use oxidizing disinfectants or sodium hypochlorite solution for cyclic sterilization; When the hardness of the water source treated by the electrodialyzer is greater than 20 mg / L, the electrodialyzer is cleaned by acid washing, alkali washing and acid washing in sequence; When the hardness of the water source treated by the electrodialyser is ≤20mg / L, the electrodialyser is cleaned by alkaline washing and acid washing in sequence.

2. The method for cleaning electrodialyser fouling according to claim 1, characterized in that: Cyclic sterilization using oxidizing sterilants includes: The oxidizing bactericide is circulated in the electrodialyzer for 1-2 hours and then soaked for 1-2 hours; After the soaking is completed, the oxidizing bactericide is circulated in the electrodialyzer for 1 hour, and the oxidizing bactericide in the electrodialyzer is replaced with clean water.

3. The method for cleaning electrodialyser fouling according to claim 1, characterized in that: The method of using sodium hypochlorite solution for circulatory sterilization includes: after the sodium hypochlorite solution circulates in the electrodialyzer for 30-45 minutes, the sodium hypochlorite solution in the electrodialyzer is replaced by clean water.

4. The method for cleaning electrodialyser fouling according to claim 1, characterized in that: The pickling comprises: Use industrial hydrochloric acid to prepare a hydrochloric acid solution with a pH value of 2-3; The hydrochloric acid solution is circulated in the electrodialyzer for 2-4 hours and then immersed for 1-2 hours; After the soaking is completed, the hydrochloric acid solution is circulated in the electrodialyzer for 2 hours, and the hydrochloric acid solution in the electrodialyzer is rinsed with clean water until the pH value is neutral.

5. The method for cleaning electrodialyser fouling according to claim 1, characterized in that: The alkali washing comprises: After preparing a caustic soda solution with a pH value of 11.5-13 using caustic soda, EDTA and sodium tripolyphosphate are added to form a cleaning solution; The cleaning solution is circulated in the electrodialyzer for 2-4 hours and then immersed for 1-2 hours; After the soaking is completed, the cleaning solution is circulated in the electrodialyzer for 2 hours, and the cleaning solution in the electrodialyzer is rinsed with clean water until the pH value is neutral.

6. The method for cleaning electrodialyser fouling according to claim 5, characterized in that: The concentration of the caustic soda solution and the EDTA mixed solution is 0.5-1.0%; the concentration of the cleaning solution is 2%.

7. The method for cleaning electrodialyser fouling according to claim 1, characterized in that: The oxidizing fungicide includes isothiazolinone fungicide and bromine oxidizing fungicide.

8. The method for cleaning fouling of an electrodialyser according to claim 7, characterized in that: The isothiazolinone fungicide includes at least one of 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one.

9. The method for cleaning electrodialyser fouling according to claim 7, characterized in that: The bromine-based oxidizing fungicide includes at least one of a polybrominated compound fungicide, a brominated phenol fungicide and a brominated amine fungicide.

10. The method for cleaning fouling of an electrodialyser according to claim 1, characterized in that: The mass concentration of the oxidizing bactericide is 0.03-0.1%, and the mass concentration of the sodium hypochlorite solution is 0.01-0.05%.