Organic pollution cleaning agent for reverse osmosis membrane in printing and dyeing industry

Abstract

The invention belongs to the technical field of reverse osmosis membrane cleaning, and discloses a reverse osmosis membrane organic pollution cleaning agent in the printing and dyeing industry. The reverse osmosis membrane organic pollution cleaning agent in the printing and dyeing industry is prepared from the following components in parts by mass: 0.3 to 1.7 parts of sodium tripolyphosphate, 0.07 to 0.60 part of sodium hydroxide, 0.3 to 1.2 parts of sodium ethylene diamine tetracetate, 0.35 to 0.65 part of sodium chloride or potassium chloride, 0.008 to 0.065 part of sodium dodecyl benzene sulfonate, 0.008 to 1 part of fatty alcohol-polyoxyethylene ether and 0.015 to 3 parts of coconut oil fatty acid monoethanolamide. The cleaning agent disclosed by the invention is simple to prepare, is short in cleaning time and long in cleaning period aiming at organic pollution and microbial pollution of the reverse osmosis membrane for recycling printing and dyeing reclaimed water, can improve membrane flux and desalination rate after cleaning, and also can reduce differential pressure energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of reverse osmosis membrane cleaning, in particular to a reverse osmosis membrane organic pollution cleaning agent for the printing and dyeing industry. Background Art

[0002] The printing and dyeing industry is a major wastewater discharger. The daily discharge of printing and dyeing wastewater in China is 3×10 6 ~4×10 6 m 3 Among them, the annual wastewater discharged by dyeing and weaving factories nationwide accounts for 80% of the total wastewater discharged by the entire textile industry. The composition of printing and dyeing wastewater has the characteristics of high organic content, high COD, low biodegradability, anti-oxidation, high chroma, and strong alkalinity. Therefore, the wastewater from the dyeing and weaving industry has become one of the most difficult industrial wastewaters to treat in China.

[0003] At present, most of the domestic printing and dyeing wastewater treatment adopts UF+RO double membrane method, and the effluent can meet the reuse standard. In recent years, with the use of a large number of synthetic degradable dyes and auxiliaries, the difficulty of treating organic matter in wastewater has gradually increased. Some difficult-to-degrade organic matter is retained on the RO membrane. The presence of organic matter provides a nutrient breeding ground for microorganisms, resulting in a composite pollution type of organic pollution and microbial pollution on the RO membrane, as well as an increase in the pressure difference of the RO system, a decrease in the RO membrane flux, and a decrease in the desalination rate, which further leads to an increase in operating costs and a decrease in water production.

[0004] Patent CN106630011A provides a combined cleaning method for a reverse osmosis system for water reuse in printing and dyeing wastewater, which includes cleaning the reverse osmosis membrane with a cleaning solution, and the cleaning solution includes three cleaning agent aqueous solutions: non-oxidizing bactericide, organic pollution cleaning agent and descaling agent. However, the method disclosed in the patent has the same cleaning method for the first stage RO and the second stage RO, lacks targeted cleaning for different pollution of the first stage RO and the second stage RO, and the chemical cleaning of printing and dyeing wastewater requires three replacements and cleaning of agents (non-oxidizing bactericide, organic pollutant cleaning agent, descaling agent), which is cumbersome to operate and takes a long time to clean. Patent CN115779695A discloses a reverse osmosis membrane organic pollution cleaning agent and its preparation method, which includes, by mass percentage: 4-6% sodium hydroxide, 7-9% dispersant, 5-7% synergist, 12-17% integrator, 5% surfactant, 1-3% hydrolase, and the balance is deionized water. The cleaning agent disclosed in this patent is for a broad spectrum of RO membrane pollution. However, the membrane pollutants in printing and dyeing wastewater are difficult to degrade and complex. If the chemical cleaning agent is not used for cleaning thoroughly, it will lead to problems such as short cleaning cycle and high operating costs.

[0005] In summary, the existing broad-spectrum chemical alkaline organic pollution cleaning agents have the problems of incomplete cleaning of RO membranes, long cleaning time and short cleaning cycle, which urgently need to be improved. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology, and to provide a reverse osmosis membrane organic pollution cleaning agent for the printing and dyeing industry to solve the problems that the existing broad-spectrum chemical alkaline organic pollution cleaning agents do not clean the RO membrane thoroughly, have a long cleaning time and a short cleaning cycle.

[0007] To achieve the purpose of the present invention, the reverse osmosis membrane organic pollution cleaning agent for the printing and dyeing industry of the present invention comprises, by mass, 0.3-1.7 parts of sodium tripolyphosphate, 0.07-0.60 parts of sodium hydroxide, 0.3-1.2 parts of sodium ethylenediaminetetraacetate, 0.35-0.65 parts of sodium chloride or potassium chloride, 0.008-0.065 parts of sodium dodecylbenzene sulfonate, 0.008-1 parts of fatty alcohol polyoxyethylene ether, and 0.015-3 parts of coconut fatty acid monoethanolamide.

[0008] Furthermore, in some embodiments of the present invention, the reverse osmosis membrane organic pollution cleaning agent for the printing and dyeing industry comprises, by mass, 0.45-1.55 parts of sodium tripolyphosphate, 0.09-0.55 parts of sodium hydroxide, 0.45-1.05 parts of sodium ethylenediaminetetraacetate, 0.4-0.6 parts of sodium chloride or potassium chloride, 0.009-0.055 parts of sodium dodecylbenzene sulfonate, 0.008-0.12 parts of fatty alcohol polyoxyethylene ether, and 0.015-0.5 parts of coconut fatty acid monoethanolamide.

[0009] Furthermore, in some embodiments of the present invention, the reverse osmosis membrane organic pollution cleaning agent for the printing and dyeing industry comprises, by mass, 0.5-1.5 parts of sodium tripolyphosphate, 0.1-0.5 parts of sodium hydroxide, 0.5-1 parts of sodium ethylenediaminetetraacetate, 0.45-0.55 parts of sodium chloride or potassium chloride, 0.01-0.05 parts of sodium dodecylbenzene sulfonate, 0.01-0.1 parts of fatty alcohol polyoxyethylene ether, and 0.02-0.3 parts of coconut fatty acid monoethanolamide.

[0010] Furthermore, in some embodiments of the present invention, the pH of the organic pollution cleaning agent for reverse osmosis membranes in the printing and dyeing industry is 12-13.

[0011] The above cleaning agent is simple to prepare, has a short chemical cleaning time, a long chemical cleaning interval, and saves energy. In some embodiments of the present invention, the cleaning steps of the organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry include:

[0012] (1) Preparation of alkaline cleaning agent: Use deionized water or RO produced water to prepare the organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry, and use a chemical cleaning pump to circulate for 15-25 minutes to complete the preparation of the chemical cleaning agent;

[0013] (2) Alkali washing: Turn on the chemical washing water pump of the chemical washing system of the reverse osmosis membrane system to fill the RO membrane shell with alkaline washing liquid. The circulation flow rate of a single membrane is 6-9m 3 / h, according to the specific system, calculate the required cleaning flow rate, circulate cleaning for 4-6h, soak for 4-6h, and complete the alkaline cleaning process;

[0014] (3) Rinsing: Use deionized water or RO produced water to circulate and clean the alkaline cleaning solution in the membrane shell for 25-35 minutes, and wash 2-4 times to complete the rinsing process;

[0015] (4) Prepare pickling agent: prepare pickling agent with deionized water or RO produced water, and circulate it with a chemical cleaning pump for 15-25 minutes to complete the preparation of the pickling agent;

[0016] (5) Acid washing: Turn on the chemical cleaning water pump of the chemical cleaning system of the reverse osmosis membrane system to fill the RO membrane shell with alkaline washing liquid. The circulation flow rate of a single membrane is 6-9m 3 / h, according to the specific system, calculate the required cleaning flow, cycle cleaning for 2-4h, soak for 2-4h, and complete the pickling process;

[0017] (6) Rinsing: Use deionized water or RO produced water to circulate and clean the alkaline cleaning solution in the membrane shell for 25-35 minutes, and wash 2-4 times to complete the rinsing process;

[0018] (7) Chemical cleaning is completed.

[0019] Furthermore, in some embodiments of the present invention, the pickling agent in step (4) is oxalic acid.

[0020] The cleaning agent of the invention is simple to prepare and can be used for organic pollution and microbial pollution of reverse osmosis membranes for recycling dyeing and printing water. The cleaning time is short and the cycle is long. After cleaning, the membrane flux and desalination rate can be improved and the pressure difference energy consumption can be reduced. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. Additional aspects and advantages of the present invention will be given in part in the following description, and part will become apparent from the following description, or will be understood through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not intended to limit the present invention.

[0022] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0023] When amount, concentration or other value or parameter is expressed as range, preferred range or a series of upper preferred value and lower preferred value limit range, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0024] Singular forms include plural references unless the context clearly indicates otherwise. "Optional" or "either" means that the subsequently described event or incident may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0025] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0026] In addition, the descriptions of the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" described below mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0027] Example 1

[0028] Clean a section of RO membrane for recycling water from a printing and dyeing plant, install it in an offline cleaning device, clean 100L of RO produced water in the water tank, weigh 500g of sodium tripolyphosphate, 100g of sodium hydroxide, 500g of EDTA-4Na, 500g of sodium chloride, 10g of sodium dodecylbenzene sulfonate, 10g of fatty alcohol polyoxyethylene ether, and 20g of coconut fatty acid monoethanolamide (the pH of the cleaning agent is between 12-13), and circulate it for 20min using a chemical cleaning pump to complete the preparation of the alkaline cleaning solution; circulate the alkaline cleaning for 5h, soak for 5h, empty it, rinse it with RO produced water for 30min, rinse it 3 times, weigh 200g of oxalic acid into the cleaning water tank containing 100L of RO produced water, circulate it for 20min using a chemical cleaning pump to complete the preparation of the acid cleaning solution, circulate the acid cleaning for 3h, soak it for 3h, empty it, rinse it with RO produced water for 30min, rinse it 3 times, complete the chemical cleaning, and detect the changes in produced water flux, desalination rate, and pressure difference.

[0029] Example 2

[0030] Clean a section of RO membrane for recycling water from a printing and dyeing plant, install it in an offline cleaning device, clean 100L of RO produced water in the water tank, weigh 1500g of sodium tripolyphosphate, 500g of sodium hydroxide, 1000g of EDTA-4Na, 500g of sodium chloride, 50g of sodium dodecylbenzene sulfonate, 100g of fatty alcohol polyoxyethylene ether, and 300g of coconut fatty acid monoethanolamide (the pH of the cleaning agent is between 12-13), and circulate it for 20min using a chemical cleaning pump to complete the preparation of the alkaline cleaning solution; circulate the alkaline cleaning for 5h, soak for 5h, empty it, rinse it with RO produced water for 30min, rinse it 3 times, weigh 200g of oxalic acid into the cleaning water tank containing 100L of RO produced water, circulate it for 20min using a chemical cleaning pump to complete the preparation of the acid cleaning solution, circulate the acid cleaning for 3h, soak it for 3h, empty it, rinse it with RO produced water for 30min, rinse it 3 times, complete the chemical cleaning, and detect the changes in produced water flux, desalination rate, and pressure difference.

[0031] Comparative Example 1

[0032] A section of RO membrane for recycling recycled water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 100g of sodium hydroxide and 25g of sodium dodecylbenzene sulfonate were weighed and circulated by a chemical cleaning pump for 20min to prepare the alkaline washing solution. The alkaline washing was circulated for 5h, soaked for 5h, drained, rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into the cleaning water tank containing 100L of RO produced water, and circulated by a chemical cleaning pump for 20min to prepare the acid washing solution. The acid washing was circulated for 3h, soaked for 3h, drained, rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. The changes in produced water flux, desalination rate and pressure difference were detected.

[0033] Comparative Example 2

[0034] A section of RO membrane for recycling recycled water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 100g of sodium hydroxide and 500g of EDTA-4Na were weighed and circulated by a chemical cleaning pump for 20min to prepare the alkaline washing solution. The alkaline washing was circulated for 5h, soaked for 5h, drained, rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into the cleaning water tank containing 100L of RO produced water, and circulated by a chemical cleaning pump for 20min to prepare the acid washing solution. The acid washing was circulated for 3h, soaked for 3h, drained, rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. The changes in produced water flux, desalination rate and pressure difference were detected.

[0035] Comparative Example 3

[0036] A section of RO membrane for recycling recycled water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 2000g of sodium tripolyphosphate and 500g of EDTA-4Na were weighed and circulated by a chemical cleaning pump for 20min to prepare the alkaline washing solution. The alkaline washing was circulated for 5h, soaked for 5h, drained, rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into the cleaning water tank containing 100L of RO produced water, and circulated by a chemical cleaning pump for 20min to prepare the acid washing solution. The acid washing was circulated for 3h, soaked for 3h, drained, rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. The changes in produced water flux, desalination rate and pressure difference were detected.

[0037] Comparative Example 4

[0038] A section of RO membrane for recycling recycled water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 3000g of sodium polyphosphate, 150g of fatty alcohol polyoxyethylene ether, 200g of citric acid and 200mL of ammonia water were weighed and circulated for 20min using a chemical cleaning pump to prepare the alkaline washing solution. The alkaline washing was circulated for 5h, soaked for 5h, drained, rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into the cleaning water tank containing 100L of RO produced water, and circulated for 20min using a chemical cleaning pump to prepare the acid washing solution. The acid washing was circulated for 3h, soaked for 3h, drained, rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. The changes in produced water flux, desalination rate and pressure difference were detected.

[0039] Comparative Example 5

[0040] A section of RO membrane for recycling recycled water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 1000g of EDTA-4Na, 120g of sodium dodecylbenzene sulfonate and 200g of NaOH were weighed and circulated by a chemical cleaning pump for 20min to prepare the alkaline washing solution. The alkaline washing was circulated for 5h, soaked for 5h, drained, rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into the cleaning water tank containing 100L of RO produced water, and circulated by a chemical cleaning pump for 20min to prepare the acid washing solution. The acid washing was circulated for 3h, soaked for 3h, drained, rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. The changes in produced water flux, desalination rate and pressure difference were detected.

[0041] Comparative Example 6

[0042] A section of RO membrane for recycling water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 1500g of sodium tripolyphosphate, 500g of sodium hydroxide, 1000g of EDTA-4Na, 500g of sodium chloride, 50g of sodium dodecylbenzene sulfonate, and 300g of coconut fatty acid monoethanolamide (the pH of the cleaning agent was between 12 and 13) were weighed, and the membranes were circulated for 20min using a chemical cleaning pump to prepare an alkaline cleaning solution. The alkaline cleaning was circulated for 5h, soaked for 5h, drained, and rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into a cleaning water tank containing 100L of RO produced water, and the membranes were circulated for 20min using a chemical cleaning pump to prepare an acid cleaning solution. The acid cleaning was circulated for 3h, soaked for 3h, drained, and rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. Changes in produced water flux, desalination rate, and pressure difference were detected.

[0043] Comparative Example 7

[0044] A section of RO membrane for recycling recycled water from a printing and dyeing plant was cleaned and installed in an offline cleaning device. 100L of RO produced water was washed in the water tank. 1500g of sodium tripolyphosphate, 750g of sodium hydroxide, 1000g of EDTA-4Na, 500g of sodium chloride, 50g of sodium dodecylbenzene sulfonate, 100g of fatty alcohol polyoxyethylene ether, and 300g of coconut fatty acid monoethanolamide (the pH of the cleaning agent was between 12 and 13) were weighed, and the membrane was circulated for 20min using a chemical cleaning pump to prepare an alkaline cleaning solution. The alkaline cleaning was circulated for 5h, soaked for 5h, drained, and rinsed with RO produced water for 30min, rinsed 3 times, 200g of oxalic acid was weighed into a cleaning water tank containing 100L of RO produced water, and the membrane was circulated for 20min using a chemical cleaning pump to prepare an acid cleaning solution. The acid cleaning was circulated for 3h, soaked for 3h, drained, and rinsed with RO produced water for 30min, rinsed 3 times, and chemical cleaning was completed. Changes in produced water flux, desalination rate, and pressure difference were detected.

[0045] The changes in the final water production flux, desalination rate and pressure difference of the above embodiments and comparative examples are shown in the following table.

[0046] Detection items Flux after cleaning (LMH) Desalination rate after cleaning Pressure difference after cleaning (Mpa) Example 1 18.76 99.13％ 0.07 Example 2 16.76 99.63％ 0.07 Comparative Example 1 13.51 98.34％ 0.1 Comparative Example 2 14.35 98.12％ 0.1 Comparative Example 3 15.31 97.35％ 0.12 Comparative Example 4 14.35 98.85％ 0.1 Comparative Example 5 13.39 98.12％ 0.1 Comparative Example 6 15.31 98.8％ 0.09 Comparative Example 7 14.95 99.1％ 0.1

[0047] As can be seen from the above table, the RO membrane is thoroughly cleaned by using the reverse osmosis membrane organic pollution cleaning agent of the present invention. After cleaning, the membrane flux and desalination rate are improved, and the pressure difference energy consumption is reduced. The effect is significantly better than the cleaning agent of the prior art.

[0048] It will be easily understood by those skilled in the art that the above description is merely an example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cleaning agent for organic pollution of reverse osmosis membrane in printing and dyeing industry, characterized in that: The reverse osmosis membrane organic pollution cleaning agent for the printing and dyeing industry comprises, by weight, 0.3-1.7 parts of sodium tripolyphosphate, 0.07-0.60 parts of sodium hydroxide, 0.3-1.2 parts of sodium ethylenediaminetetraacetate, 0.35-0.65 parts of sodium chloride or potassium chloride, 0.008-0.065 parts of sodium dodecylbenzene sulfonate, 0.008-1 parts of fatty alcohol polyoxyethylene ether, and 0.015-3 parts of coconut fatty acid monoethanolamide.

2. The organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry according to claim 1, characterized in that: The printing and dyeing industry reverse osmosis membrane organic pollution cleaning agent comprises, by weight, 0.45-1.55 parts of sodium tripolyphosphate, 0.09-0.55 parts of sodium hydroxide, 0.45-1.05 parts of sodium ethylenediaminetetraacetate, 0.4-0.6 parts of sodium chloride or potassium chloride, 0.009-0.055 parts of sodium dodecylbenzene sulfonate, 0.008-0.12 parts of fatty alcohol polyoxyethylene ether, and 0.015-0.5 parts of coconut fatty acid monoethanolamide.

3. The organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry according to claim 1, characterized in that: The printing and dyeing industry reverse osmosis membrane organic pollution cleaning agent comprises, by weight, 0.5-1.5 parts of sodium tripolyphosphate, 0.1-0.5 parts of sodium hydroxide, 0.5-1 parts of sodium ethylenediaminetetraacetate, 0.45-0.55 parts of sodium chloride or potassium chloride, 0.01-0.05 parts of sodium dodecylbenzene sulfonate, 0.01-0.1 parts of fatty alcohol polyoxyethylene ether, and 0.02-0.3 parts of coconut fatty acid monoethanolamide.

4. The organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry according to any one of claims 1 to 3, characterized in that: The pH value of the organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry is 12-13.

5. The cleaning agent for organic pollution of reverse osmosis membrane in printing and dyeing industry according to any one of claims 1 to 3, characterized in that: The cleaning steps of the reverse osmosis membrane organic pollution cleaning agent in the printing and dyeing industry include: (1) Preparation of alkaline cleaning agent: Use deionized water or RO produced water to prepare the organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry, and use a chemical cleaning pump to circulate for 15-25 minutes to complete the preparation of the chemical cleaning agent; (2) Alkali washing: Turn on the chemical washing water pump of the chemical washing system of the reverse osmosis membrane system to fill the RO membrane shell with alkaline washing liquid. The circulation flow rate of a single membrane is 6-9m 3 / h, according to the specific system, calculate the required cleaning flow rate, circulate cleaning for 4-6h, soak for 4-6h, and complete the alkaline cleaning process; (3) Rinsing: Use deionized water or RO produced water to circulate and clean the alkaline cleaning solution in the membrane shell for 25-35 minutes, and wash 2-4 times to complete the rinsing process; (4) Prepare pickling agent: prepare pickling agent with deionized water or RO produced water, and circulate it with a chemical cleaning pump for 15-25 minutes to complete the preparation of the pickling agent; (5) Acid washing: Turn on the chemical cleaning water pump of the chemical cleaning system of the reverse osmosis membrane system to fill the RO membrane shell with alkaline washing liquid. The circulation flow rate of a single membrane is 6-9m 3 / h, according to the specific system, calculate the required cleaning flow rate, circulate cleaning for 2-4h, soak for 2-4h, and complete the pickling process; (6) Rinsing: Use deionized water or RO produced water to circulate and clean the alkaline cleaning solution in the membrane shell for 25-35 minutes, and wash 2-4 times to complete the rinsing process; (7) Chemical cleaning is completed.

6. The organic pollution cleaning agent for reverse osmosis membrane in the printing and dyeing industry according to claim 5, characterized in that: In the step (4), the pickling agent is oxalic acid.