Chemical washing method of reverse osmosis membrane for treating mine water

Abstract

The invention relates to a chemical washing method of a reverse osmosis membrane for treating mine water. The chemical washing method comprises neutral reduction complexing washing, acid washing and alkaline buffer washing, the detergent for neutral reductive complexing washing is water-based and comprises alcohol, a chelate, a reducing agent and a surfactant, a washing agent of the acid washing agent is a water base, the pH value is 1.5-2.0, and the acid washing agent further comprises a surfactant and a scale inhibitor; a washing agent for alkaline buffer washing is a water base, the pH value is 11-12, and the alkaline buffer washing agent further comprises a surfactant and a scale inhibitor. According to the method, the water outlet efficiency of the reverse osmosis membrane is improved, meanwhile, the damage of conventional chemical washing to the reverse osmosis membrane can be remarkably reduced, and the service life of the reverse osmosis membrane is prolonged.

Description

Technical Field

[0001] The present invention relates to a chemical washing method for a filter membrane, and particularly to a chemical washing method for a reverse osmosis membrane. Background Art

[0002] When a reverse osmosis membrane is working properly, it is under high pressure for a long time to intercept larger molecules and particles, thereby reducing the impurity concentration in water. As the operation time increases, the solute concentration near the membrane surface gradually increases, and the phenomenon of concentration polarization intensifies, resulting in problems such as a decrease in water production and desalination rate, which affects the performance of the reverse osmosis membrane. Reverse osmosis membranes are widely used in mine water treatment systems. Generally, after about two months of operation, the water output of the reverse osmosis membrane will be reduced to 1 / 3 of that of a newly replaced membrane, and the blockage is relatively serious. In order to restore the water permeability and desalination performance of the reverse osmosis membrane, there are two common methods. One method is to replace the reverse osmosis membrane as a whole. Generally, the reverse osmosis membrane is replaced every six months. Replacing the reverse osmosis membrane can effectively restore the operation efficiency of the water treatment system, but due to frequent membrane replacement, the production cost is significantly increased, so it is generally not adopted. The second is to chemically clean the reverse osmosis membrane regularly. This method is simple to operate and has a low cost, and is widely used.

[0003] The thickness of the reverse osmosis membrane is usually in the micron range, and the pore diameter is generally between 0.0003 - 0.015 μm. Its structure is relatively fragile, and the cleaning process often also damages the reverse osmosis membrane. Especially when using chemical agents for cleaning, it is easy to reduce the service life of the membrane. The cleaning effect of the reverse osmosis membrane can be measured by the water output and desalination rate. When the water output of the reverse osmosis membrane decreases significantly, it generally indicates that there is a situation of pollutant blockage and the reverse osmosis membrane has not been sufficiently cleaned; when the desalination rate decreases significantly, it generally indicates that the structure of the reverse osmosis membrane is damaged and the filtration effect becomes poor. For the cleaning of reverse osmosis membranes, there are already some publicly available technologies, and the manufacturers of reverse osmosis membranes will also provide technical support for cleaning. However, these methods generally have problems such as insufficient cleaning effect, or sufficient cleaning effect but too much damage to the structure of the reverse osmosis membrane, and cannot achieve effective protective cleaning of the reverse osmosis membrane. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art and provide a chemical washing method for a reverse osmosis membrane for treating mine water that can achieve protective cleaning.

[0005] The technical solution adopted by the present invention to solve its technical problems is as follows: A chemical washing method for a reverse osmosis membrane for treating mine water includes neutral reduction complex washing, acidic washing, and alkaline slow flushing; the processes of the neutral reduction complex washing, acidic washing, and alkaline slow flushing all respectively include: detergent circulating washing, detergent soaking, and clean water rinsing;

[0006] The detergent for the neutral reduction complex washing is water-based and includes alcohol, chelate, reducing agent and surfactant; in the detergent for the neutral reduction complex washing, the concentration of alcohol is 2 wt% to 10 wt%, the concentration of chelate is 0.1 wt% to 1 wt%, the concentration of reducing agent is 0.05 wt% to 0.5 wt%, and the concentration of surfactant is 0.1 wt% to 1 wt%;

[0007] The detergent for the acidic washing is water-based, with a pH value of 1.5 to 2.0, and also includes surfactant and scale inhibitor; in the detergent for the acidic washing, the concentration of surfactant is 0.1 wt% to 1 wt%, and the concentration of scale inhibitor is 0.3 wt% to 2 wt%;

[0008] The detergent for the alkaline flushing washing is water-based, with a pH value of 11 to 12, and also includes surfactant and scale inhibitor; in the detergent for the alkaline flushing washing, the concentration of surfactant is 0.1 wt% to 1 wt%, and the concentration of scale inhibitor is 0.3 wt% to 2 wt%.

[0009] Preferably, in the detergent for the neutral reduction complex washing, the alcohol concentration is 4 wt% to 6 wt%.

[0010] Preferably, in the detergent for the neutral reduction complex washing, the chelate concentration is 0.2 wt% to 0.4 wt%.

[0011] Preferably, in the detergent for the neutral reduction complex washing, the reducing agent concentration is 0.1 wt% to 0.2 wt%.

[0012] Preferably, in the detergent for the neutral reduction complex washing, the surfactant concentration is 0.3 wt% to 0.5 wt%.

[0013] Preferably, in the detergent for the acidic washing, the surfactant concentration is 0.5 wt% to 0.8 wt%.

[0014] Preferably, in the detergent for the acidic washing, the scale inhibitor concentration is 0.8 wt% to 1.2 wt%.

[0015] Preferably, in the detergent for the alkaline flushing washing, the surfactant concentration is 0.5 wt% to 0.8 wt%.

[0016] Preferably, in the detergent for the alkaline flushing washing, the scale inhibitor concentration is 0.8 wt% to 1.2 wt%.

[0017] Preferably, the process of the neutral reduction complex washing includes: detergent circulating washing, detergent soaking, and rinsing with clear water.

[0018] Preferably, the process of acid washing includes: the first cycle washing with detergent, soaking with detergent, the second cycle washing with detergent, and rinsing with clear water.

[0019] Preferably, the process of alkaline gentle rinsing includes: the first cycle washing with detergent, soaking with detergent, the second cycle washing with detergent, and rinsing with clear water.

[0020] Preferably, the cycle washing time of the neutral reduction complex washing is 25 min to 35 min.

[0021] Preferably, the soaking time of the neutral reduction complex washing is 25 min to 35 min.

[0022] Preferably, after the neutral reduction complex washing, it is rinsed with water for 25 min to 35 min.

[0023] Preferably, the first cycle washing time of the acid washing is 25 to 35 min.

[0024] Preferably, the soaking time of the acid washing is 25 to 35 min.

[0025] Preferably, the second cycle washing time of the acid washing is 25 to 35 min.

[0026] Preferably, the first cycle washing time of the alkaline gentle rinsing is 25 min to 35 min.

[0027] Preferably, the soaking time of the alkaline gentle rinsing is 35 min to 45 min.

[0028] Preferably, the second cycle washing time of the alkaline gentle rinsing is 8 min to 12 min.

[0029] Preferably, in the detergent for the neutral reduction complex washing, the alcohol includes ethanol.

[0030] Preferably, in the detergent for the neutral reduction complex washing, the chelating agents include two or more of tetrasodium glutamate diacetate, trisodium methylglycine diacetate, tetrasodium aspartate diacetate, and hydroxyethane diphosphonic acid.

[0031] Preferably, in the detergent for the neutral reduction complex washing, the reducing agent includes sodium sulfite.

[0032] Preferably, in the detergent for the neutral reduction complex washing, the surfactants include alcohol ether carboxylate and alkyl polyglycoside.

[0033] Preferably, in the detergent for the acid washing, the acids include hydrochloric acid, phosphoric acid, and citric acid.

[0034] Preferably, in the detergent for acid washing, the surfactant includes alcohol ether carboxylate and alkyl glycoside.

[0035] Preferably, in the detergent for acid washing, the scale inhibitor includes polyacrylic acid.

[0036] More preferably, in the detergent for acid washing, the mass ratio of hydrochloric acid, phosphoric acid and citric acid is 2.5 - 3.5∶0.8 - 1.2∶1.

[0037] Preferably, in the detergent for alkaline flushing, the alkali includes sodium hydroxide, trisodium phosphate and sodium citrate.

[0038] Preferably, in the detergent for alkaline flushing, the surfactant includes alcohol ether carboxylate and alkyl glycoside.

[0039] Preferably, in the detergent for alkaline flushing, the scale inhibitor includes acrylic acid - hydroxypropyl acrylate copolymer.

[0040] More preferably, in the detergent for alkaline flushing, the mass ratio of sodium hydroxide, trisodium phosphate and sodium citrate is 5 - 8∶1.6 - 2.2∶1.

[0041] Preferably, after the acid washing, the reverse osmosis membrane is rinsed with water until it is neutral.

[0042] Preferably, during the two - cycle washing process of the acid washing, by updating the detergent, the pH value during the washing process is maintained at 1.5 - 2.0.

[0043] Preferably, after the alkaline flushing, the reverse osmosis membrane is rinsed with water until it is neutral.

[0044] Preferably, during the two - cycle washing process of the alkaline flushing, by updating the detergent, the pH value during the washing process is maintained at 11 - 12.

[0045] Preferably, the mine water contains one or more of copper, cobalt, iron, aluminum and manganese.

[0046] Preferably, the separation layer material of the reverse osmosis membrane is polyamide.

[0047] Preferably, the aperture of the reverse osmosis membrane is below 0.020μm.

[0048] The present invention has the following beneficial effects:

[0049] (1) The method of the present invention can improve the water output efficiency of the reverse osmosis membrane while significantly reducing the damage caused by conventional chemical washing to the reverse osmosis membrane and prolonging the service life of the reverse osmosis membrane.

[0050] (2) The desalination rate of the reverse osmosis membrane treated by the method of the present invention is increased by more than 3 m 3 / h compared with cleaning by other methods, the water yield rate is increased by more than 3% compared with other methods, and the number of cleaning times that the reverse osmosis membrane can withstand is increased by more than 3 times compared with other chemical cleaning methods, significantly improving the service life and filtration effect of the reverse osmosis membrane;

[0051] (3) The method of the present invention has no special requirements for equipment and devices, and existing conventional chemical washing equipment can be used, and the process is easy to implement.

[0052] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below. Specific embodiments

[0053] In order to make the purposes, solutions and beneficial technologies of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be noted that the embodiments described in this specification are only for explaining the present invention and not for limiting the present invention.

[0054] For the sake of simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, although not explicitly recited, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be used as its own lower or upper limit and combined with any other point or single value or combined with other lower or upper limits to form a range not explicitly recited.

[0055] In the description herein, it should be noted that unless otherwise specified, "above" and "below" include this number, the "multiple" in "one or more" means two or more, and the "multiple" in "one or more" means two or more.

[0056] The embodiment of the present invention provides a chemical washing method for a reverse osmosis membrane for treating mine water, including neutral reduction complex washing, acid washing and alkaline slow flushing; the processes of the neutral reduction complex washing, acid washing and alkaline slow flushing respectively include: detergent circulating washing, detergent soaking and clean water rinsing;

[0057] The detergent for the neutral reduction complex washing is water-based and includes alcohol, chelate, reducing agent and surfactant; in the detergent for the neutral reduction complex washing, the concentration of alcohol is 2 wt% to 10 wt%, the concentration of chelate is 0.1 wt% to 1 wt%, the concentration of reducing agent is 0.05 wt% to 0.5 wt%, and the concentration of surfactant is 0.1 wt% to 1 wt%;

[0058] The acid-washing detergent is water-based, with a pH value of 1.5 to 2.0, and also includes a surfactant and a scale inhibitor; in the acid-washing detergent, the concentration of the surfactant is 0.1 wt% to 1 wt%, and the concentration of the scale inhibitor is 0.3 wt% to 2 wt%.

[0059] The alkaline slow-rinse detergent is water-based, with a pH value of 11 to 12, and also includes a surfactant and a scale inhibitor; in the alkaline slow-rinse detergent, the concentration of the surfactant is 0.1 wt% to 1 wt%, and the concentration of the scale inhibitor is 0.3 wt% to 2 wt%.

[0060] The performance attenuation of the reverse osmosis membrane for treating mine water is mainly due to the following reasons: (1) Inorganic pollutants, mainly manifested as carbonate deposition and scaling, non-carbonate precipitation and scaling, and iron, aluminum, and silica colloid substances; (2) Organic pollutants, mainly humic acid, protein, and polysaccharide substances; Biological pollutants, mainly the reproduction of microorganisms and their metabolites. Under normal operating conditions, the reverse osmosis membrane may be contaminated or blocked by these substances. These substances deposited on the membrane surface will cause a decrease in the permeation rate and a reduction in the salt rejection rate of the reverse osmosis membrane.

[0061] For the various pollutants involved, the embodiments of the present invention adopt a combined washing method of neutral reduction complexing washing, acid washing, and alkaline slow rinsing, making full use of the synergistic effect between the agents to achieve an efficient washing effect. Adding a scale inhibitor in acid washing and alkaline washing can prevent impurities in the washing process from causing secondary pollution to the reverse osmosis membrane. Generally speaking, the combined washing also means an increase in the total cleaning time and frequency, and a longer process of damaging the membrane structure, which often reduces the service life of the membrane. However, the inventors of the present invention unexpectedly found during the research process that the combined washing method of the present invention actually increases the number of times the membrane can withstand cleaning and extends the life of the reverse osmosis membrane.

[0062] The chemical washing method for the reverse osmosis membrane for treating mine water provided by the embodiments of the present invention has the following advantages:

[0063] (1) The method of the embodiments of the present invention can improve the water output efficiency of the reverse osmosis membrane while significantly reducing the damage caused by conventional chemical washing to the reverse osmosis membrane and extending the service life of the reverse osmosis membrane;

[0064] (2) After being treated by the method of the embodiments of the present invention, the salt rejection rate of the reverse osmosis membrane is increased by more than 3 m 3 / h compared with other cleaning methods, the water output rate is increased by more than 3% compared with other methods, and the number of cleaning times that the reverse osmosis membrane can withstand is increased by more than 3 times compared with other chemical cleaning methods, significantly improving the service life and filtration effect of the reverse osmosis membrane;

[0065] (3) The method of the embodiment of the present invention has no special requirements for equipment and devices, and existing conventional chemical washing equipment can be utilized, and the process is easy to implement.

[0066] In the embodiment of the present invention, in the detergent for neutral reduction complex washing, the alcohol concentration is 4 wt% - 6 wt%.

[0067] In the embodiment of the present invention, in the detergent for neutral reduction complex washing, the chelate concentration is 0.2 wt% - 0.4 wt%.

[0068] In the embodiment of the present invention, in the detergent for neutral reduction complex washing, the reducing agent concentration is 0.1 wt% - 0.2 wt%.

[0069] In the embodiment of the present invention, in the detergent for neutral reduction complex washing, the surfactant concentration is 0.3 wt% - 0.5 wt%.

[0070] In the embodiment of the present invention, in the detergent for acid washing, the surfactant concentration is 0.5 wt% - 0.8 wt%.

[0071] In the embodiment of the present invention, in the detergent for acid washing, the scale inhibitor concentration is 0.8 wt% - 1.2 wt%.

[0072] In the embodiment of the present invention, in the detergent for alkaline flushing washing, the surfactant concentration is 0.5 wt% - 0.8 wt%.

[0073] In the embodiment of the present invention, in the detergent for alkaline flushing washing, the scale inhibitor concentration is 0.8 wt% - 1.2 wt%.

[0074] In the embodiment of the present invention, the process of neutral reduction complex washing includes: detergent circulating washing, detergent soaking, and clear water rinsing.

[0075] In the embodiment of the present invention, the process of acid washing includes: first cycle washing of the detergent, detergent soaking, second cycle washing of the detergent, and clear water rinsing.

[0076] In the embodiment of the present invention, the process of alkaline flushing washing includes: first cycle washing of the detergent, detergent soaking, second cycle washing of the detergent, and clear water rinsing.

[0077] In the embodiment of the present invention, the circulating washing time of the neutral reduction complex washing is 25 min - 35 min.

[0078] In the embodiment of the present invention, the soaking time of the neutral reduction complex washing is 25 min - 35 min.

[0079] In the embodiments of the present invention, after the neutral reduction complex washing is completed, it is rinsed with water for 25 min to 35 min. The water used should be relatively pure, for example, reverse osmosis water can be used.

[0080] In the embodiments of the present invention, the first cycle washing time of the acidic washing is 25 to 35 min.

[0081] In the embodiments of the present invention, the soaking time of the acidic washing is 25 to 35 min.

[0082] In the embodiments of the present invention, the second cycle washing time of the acidic washing is 25 to 35 min.

[0083] In the embodiments of the present invention, the first cycle washing time of the alkaline gentle washing is 25 min to 35 min.

[0084] In the embodiments of the present invention, the soaking time of the alkaline gentle washing is 35 min to 45 min.

[0085] In the embodiments of the present invention, the second cycle washing time of the alkaline gentle washing is 8 min to 12 min.

[0086] In the embodiments of the present invention, in the detergent for the neutral reduction complex washing, the alcohol includes ethanol.

[0087] In the embodiments of the present invention, in the detergent for the neutral reduction complex washing, the chelating agent includes two or more of tetrasodium glutamate diacetate, trisodium methylglycine diacetate, tetrasodium aspartate diacetate, and hydroxyethane diphosphonic acid.

[0088] In the embodiments of the present invention, in the detergent for the neutral reduction complex washing, the reducing agent includes sodium sulfite.

[0089] In the embodiments of the present invention, in the detergent for the neutral reduction complex washing, the surfactant includes alcohol ether carboxylate and alkyl polyglycoside. Both alcohol ether carboxylate and alkyl polyglycoside are environmentally friendly and biodegradable compounds.

[0090] In some embodiments of the present invention, in the detergent for the neutral reduction complex washing, the surfactant is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1 to 2:1 to 2.

[0091] In the embodiments of the present invention, in the detergent for the acidic washing, the acid includes hydrochloric acid, phosphoric acid, and citric acid.

[0092] In the embodiments of the present invention, in the detergent for the acidic washing, the surfactant includes alcohol ether carboxylate and alkyl polyglycoside. Both alcohol ether carboxylate and alkyl polyglycoside are environmentally friendly and biodegradable compounds.

[0093] In some embodiments of the present invention, in the detergent for acid washing, the surfactant is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1-2:1-2.

[0094] In the embodiments of the present invention, in the detergent for acid washing, the scale inhibitor includes polyacrylic acid. Polyacrylic acid is an environmentally friendly polymer material.

[0095] In some embodiments of the present invention, in the detergent for acid washing, the mass ratio of hydrochloric acid, phosphoric acid and citric acid is 2.5-3.5:0.8-1.2:1.

[0096] In the embodiments of the present invention, in the detergent for alkaline flushing, the alkali includes sodium hydroxide, trisodium phosphate and sodium citrate.

[0097] In the embodiments of the present invention, in the detergent for alkaline flushing, the surfactant includes alcohol ether carboxylate and alkyl polyglycoside. Both alcohol ether carboxylate and alkyl polyglycoside are environmentally friendly and biodegradable compounds.

[0098] In some embodiments of the present invention, in the detergent for alkaline flushing, the surfactant is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1-2:1-2.

[0099] In the embodiments of the present invention, in the detergent for alkaline flushing, the scale inhibitor includes acrylic acid-acrylic acid hydroxypropyl ester copolymer. Acrylic acid-acrylic acid hydroxypropyl ester copolymer is an environmentally friendly polymer compound.

[0100] In some embodiments of the present invention, in the detergent for alkaline flushing, the mass ratio of sodium hydroxide, trisodium phosphate and sodium citrate is 5-8:1.6-2.2:1.

[0101] In the embodiments of the present invention, after the acid washing, the reverse osmosis membrane is rinsed with water until it is neutral. The water used should be relatively pure, for example, reverse osmosis water can be used.

[0102] In the embodiments of the present invention, during the two-cycle washing process of the acid washing, by updating the detergent, the pH value during the washing process is maintained at 1.5-2.0.

[0103] In the embodiments of the present invention, after the alkaline flushing, the reverse osmosis membrane is rinsed with water until it is neutral. The water used should be relatively pure, for example, reverse osmosis water can be used.

[0104] In the embodiments of the present invention, during the two-cycle washing process of the alkaline flushing, by updating the detergent, the pH value during the washing process is maintained at 11-12.

[0105] In the embodiments of the present invention, the mine water contains one or more of copper, cobalt, iron, aluminum, and manganese.

[0106] In some embodiments of the present invention, the mine water comes from a copper-cobalt mine. The raw water is rich in mineral compounds of copper, cobalt, iron, aluminum, and manganese, and also contains mineral dust.

[0107] In the embodiments of the present invention, the separation layer material of the reverse osmosis membrane is polyamide.

[0108] In the embodiments of the present invention, the pore size of the reverse osmosis membrane is below 0.020 μm. Generally, the pore size of reverse osmosis membranes used for water treatment is within this range.

[0109] In some embodiments of the present invention, the pore size of the reverse osmosis membrane is 0.0003 μm to 0.015 μm.

[0110] Embodiment

[0111] The following embodiments more specifically describe the content disclosed in the present invention. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present invention are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight. Unless otherwise stated, all reagents used in the embodiments can be obtained through conventional commercial channels or synthesized according to conventional methods, and can be used directly without further treatment. Unless otherwise stated, the instruments used in the embodiments can be obtained through conventional commercial channels.

[0112] The mine water involved in each embodiment and comparative example is mine pit groundwater, and its component content is: Fe 0.06 mg / L, Cu 0.06 mg / L, Co 0.02 mg / L, Cd < 0.01 mg / L, Pb < 0.01 mg / L, Mn 0.19 mg / L, Ni < 0.01 mg / L, Zn < 0.01 mg / L.

[0113] The filtration effects of the reverse osmosis membranes after washing in each case are summarized in Table 1.

[0114] Embodiment 1

[0115] The reverse osmosis membrane for the mine water treated in this embodiment is the TM720D-400 reverse osmosis membrane produced by Toray of Japan, with a pore size of 0.0003 - 0.015 μm. The material is an inner UTC membrane sheet [including a polyamide active layer (separation layer), a polysulfone support layer, and a non-woven fabric backing layer], and the shell is FRP.

[0116] The chemical washing method of the reverse osmosis membrane for treating mine water in this embodiment includes three steps, which are: neutral reduction complex washing, acid washing, and alkaline slow flushing in sequence.

[0117] (1) The specific process of the neutral reduction complex washing is as follows: the detergent is circulated for washing for 30 minutes, soaked for 30 minutes, and rinsed with pure water for 30 minutes; the detergent for the neutral reduction complex washing is water-based and includes 5 wt% ethanol, 0.3 wt% chelating agent, 0.15 wt% reducing agent, and 0.5 wt% surfactant;

[0118] The chelating agent used is a combination of tetrasodium glutamate diacetate, trisodium methylglycine diacetate, and hydroxyethanediphosphonic acid in a mass ratio of 2:1:1;

[0119] The reducing agent used is sodium sulfite;

[0120] The surfactant used is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0121] (2) The specific process of the acidic washing is as follows: the detergent is circulated for the first time for washing for 30 minutes, soaked for 30 minutes, circulated for the second time for washing for 30 minutes, and rinsed with pure water until neutral; the detergent for the acidic washing is water-based, with a pH value of 1.5, and also includes 0.8 wt% surfactant and 0.8 wt% scale inhibitor; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5 - 2.0 during the washing process;

[0122] The substances mainly used to maintain acidity in the acidic washing are a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 2.6:1.1:1;

[0123] The surfactant used is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0124] The scale inhibitor used is polyacrylic acid;

[0125] (3) The specific process of the alkaline slow rinsing is as follows: the detergent is circulated for the first time for washing for 30 minutes, soaked for 40 minutes, circulated for the second time for washing for 10 minutes, and rinsed with pure water until neutral; the detergent for the alkaline slow rinsing is water-based, with a pH value of 11, and also includes 0.6 wt% surfactant and 1.0 wt% scale inhibitor; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 11 during the washing process;

[0126] The substances mainly used to maintain alkalinity in the alkaline slow rinsing are a combination of sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 7:2.2:1;

[0127] The surfactant used is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0128] The scale inhibitor used is an acrylic acid - hydroxypropyl acrylate copolymer;

[0129] The total cleaning time of this embodiment is 320 min; after cleaning, it is tested with mine water. The single - set reverse osmosis water output is 19 m 3 / h, and the desalination rate is 96%.

[0130] Example 2

[0131] The reverse osmosis membrane for mine water treated in this embodiment is the TM720D - 440 reverse osmosis membrane produced by Toray of Japan, with a pore size of 0.0003 - 0.015 μm. The material is an inner - layer UTC membrane sheet [including a polyamide active layer (separation layer), a polysulfone support layer, and a non - woven fabric backing layer], and the shell is FRP.

[0132] The chemical washing method of the reverse osmosis membrane for treating mine water in this embodiment includes three steps, which are in sequence: neutral reduction complex washing, acidic washing, and alkaline slow - flush washing.

[0133] (1) The specific process of the neutral reduction complex washing is: the detergent is circulated for washing for 25 min, soaked for 25 min, and rinsed with pure water for 25 min; the detergent for the neutral reduction complex washing is water - based, including 4 wt% ethanol, 0.2 wt% chelate, 0.1 wt% reducing agent, and 0.4 wt% surfactant;

[0134] The chelate used is a combination of trisodium methylglycine diacetate, tetrasodium aspartic acid diacetate, and hydroxyethane diphosphonic acid in a mass ratio of 1.5∶1∶1;

[0135] The reducing agent used is sodium sulfite;

[0136] The surfactant used is a combination of alcohol ether carboxylate and alkyl glycoside in a mass ratio of 2∶1;

[0137] (2) The specific process of the acidic washing is: the detergent is circulated for the first time for washing for 25 min, soaked for 25 min, circulated for the second time for washing for 25 min, and rinsed with pure water until neutral; the detergent for the acidic washing is water - based, with a pH value of 2, and also includes 0.5 wt% surfactant and 1.2 wt% scale inhibitor; during the two - cycle washing process, the detergent needs to be continuously updated to keep the pH value of the washing water at 2 during the washing process;

[0138] The substances mainly used to maintain acidity in the acidic washing are a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3.2∶0.8∶1;

[0139] The surfactant used is a combination of alcohol ether carboxylate and alkyl glycoside in a mass ratio of 2∶1;

[0140] The scale inhibitor used is polyacrylic acid;

[0141] (3) The specific process of the alkaline slow flushing and washing is as follows: the detergent is circulated and washed for the first time for 25 minutes, soaked for 35 minutes, circulated and washed for the second time for 8 minutes, and rinsed with pure water until neutral; the detergent for the alkaline slow flushing and washing is water-based, with a pH value of 12, and also includes 0.5 wt% of surfactant and 1.2 wt% of scale inhibitor; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water during the washing process at 11 - 12;

[0142] The main substances for maintaining alkalinity in the alkaline slow flushing and washing are: a combination of sodium hydroxide, trisodium phosphate and sodium citrate in a mass ratio of 5∶1.8∶1;

[0143] The surfactant used is: a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 2∶1;

[0144] The scale inhibitor used is acrylic acid - hydroxypropyl acrylate copolymer;

[0145] The total cleaning time of this embodiment is 280 minutes; after cleaning, it is tested with mine water, and the single - set reverse osmosis water output is 18.5 m 3 / h, and the salt rejection rate is 95.7%.

[0146] Example 3

[0147] The reverse osmosis membrane for mine water treated in this embodiment is the TM720D - 370 reverse osmosis membrane produced by Toray of Japan, with a pore size of 0.0003 - 0.015 μm, and the material is an inner - layer UTC membrane sheet [including a polyamide active layer (separation layer), a polysulfone support layer, and a non - woven fabric backing layer], and the shell is FRP.

[0148] The chemical washing method of the reverse osmosis membrane for treating mine water in this embodiment includes three steps, which are in sequence: neutral reduction complexing washing, acidic washing, and alkaline slow flushing and washing.

[0149] (1) The specific process of the neutral reduction complexing washing is as follows: the detergent is circulated and washed for 35 minutes, soaked for 35 minutes, and rinsed with pure water for 35 minutes; the detergent for the neutral reduction complexing washing is water - based, including 6 wt% of ethanol, 0.4 wt% of chelating agent, 0.2 wt% of reducing agent, and 0.3 wt% of surfactant;

[0150] The chelating agent used is: a combination of tetrasodium glutamate diacetate, tetrasodium aspartate diacetate, and hydroxyethylidene diphosphonic acid in a mass ratio of 1∶1∶2;

[0151] The reducing agent used is sodium sulfite;

[0152] The surfactants used are: the combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:2;

[0153] (2) The specific process of the acid washing is as follows: the detergent is circulated and washed for the first time for 35 min, soaked for 35 min, circulated and washed for the second time for 35 min, and rinsed with pure water until neutral; the detergent for the acid washing is water-based, with a pH value of 1.5, and also includes 0.7 wt% of surfactant and 1 wt% of scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5 - 2 during the washing process;

[0154] The substances mainly used to maintain acidity in the acid washing are: the combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0155] The surfactants used are: the combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:2;

[0156] The scale inhibitor used is polyacrylic acid;

[0157] (3) The specific process of the alkaline slow flushing is as follows: the detergent is circulated and washed for the first time for 35 min, soaked for 45 min, circulated and washed for the second time for 12 min, and rinsed with pure water until neutral; the detergent for the alkaline slow flushing is water-based, with a pH value of 12, and also includes 0.8 wt% of surfactant and 0.8 wt% of scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water at 11 - 12 during the washing process;

[0158] The substances mainly used to maintain alkalinity in the alkaline slow flushing are: the combination of sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 3:1:0.5;

[0159] The surfactants used are: the combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:2;

[0160] The scale inhibitor used is acrylic acid - hydroxypropyl acrylate copolymer;

[0161] The total cleaning time of this example is 360 min; after cleaning, it is tested with mine water, and the single - set reverse osmosis water production is 19.1 m 3 / h, and the desalination rate is 96.5%.

[0162] Example 4

[0163] The reverse osmosis membrane for treating mine water in this embodiment is the TM720D-400 reverse osmosis membrane produced by Toray of Japan, with a pore size of 0.0003-0.015 μm. The material is an inner UTC membrane sheet [including a polyamide active layer (separation layer), a polysulfone support layer, and a non-woven fabric backing layer], and the shell is FRP.

[0164] The chemical washing method of the reverse osmosis membrane for treating mine water in this embodiment includes three steps, which are, in sequence: neutral reduction complex washing, acidic washing, and alkaline slow flushing. Since the reverse osmosis membrane works under high pressure, certain damage to the membrane structure will also occur during normal operation. Cleaning the used reverse osmosis membrane can only generally illustrate the cleaning effect and cannot directly reflect the damage to the membrane structure caused by cleaning. In order to better test the damage to the membrane structure caused by cleaning, in this embodiment, the described washing method is repeated 5 times on a brand-new reverse osmosis membrane to detect the cumulative damage to the reverse osmosis membrane after multiple cleanings using the method of the present invention.

[0165] (1) The specific process of the neutral reduction complex washing is as follows: The detergent is circulated for washing for 30 minutes, soaked for 30 minutes, and rinsed with pure water for 30 minutes. The detergent for the neutral reduction complex washing is water-based and includes 5 wt% ethanol, 0.3 wt% chelating agent, 0.1 wt% reducing agent, and 0.3 wt% surfactant.

[0166] The chelating agent used is a combination of tetrasodium glutamate diacetate, tetrasodium aspartate diacetate, and hydroxyethanediphosphonic acid in a mass ratio of 1:2:1.

[0167] The reducing agent used is sodium sulfite.

[0168] The surfactant used is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1.

[0169] (2) The specific process of the acidic washing is as follows: The detergent is circulated for the first time for washing for 30 minutes, soaked for 30 minutes, circulated for the second time for washing for 30 minutes, and rinsed with pure water until neutral. The detergent for the acidic washing is water-based, with a pH value of 1.5, and also includes 0.5 wt% surfactant and 1 wt% scale inhibitor. During the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5-2 during the washing process.

[0170] The substances mainly used to maintain acidity in the acidic washing are a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1.

[0171] The surfactant used is a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1.

[0172] The scale inhibitor used is polyacrylic acid.

[0173] (3) The specific process of the alkaline slow flushing and washing is as follows: the detergent is circulated and washed for the first time for 30 min, soaked for 40 min, circulated and washed for the second time for 10 min, and rinsed with pure water until neutral; the detergent for the alkaline slow flushing and washing is water-based, with a pH value of 12, and also includes 0.6 wt% of surfactant and 1 wt% of scale inhibitor; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 11-12 during the washing process;

[0174] The substances mainly used to maintain alkalinity in the alkaline slow flushing and washing are: a combination of sodium hydroxide, trisodium phosphate and sodium citrate in a mass ratio of 3:1:0.5;

[0175] The surfactant used is: a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0176] The scale inhibitor used is acrylic acid-hydroxypropyl acrylate copolymer;

[0177] The cleaning time for each time in this embodiment is 320 min, and the total cleaning time is 1600 min; after cleaning, mine water is used for testing, and the single-stage reverse osmosis water output is 19.8 m 3 / h, and the salt rejection rate is 98.9%.

[0178] To further illustrate the implementation effect of the present invention, the following lists cases using other cleaning methods for comparison.

[0179] Comparative Example 1

[0180] The reverse osmosis membrane for mine water treated in this comparative example is the same as that in Example 1.

[0181] The difference between the chemical washing method of the reverse osmosis membrane for mine water treated in this comparative example and the solution of the present invention lies in the different detergents used: chelating agents, reducing agents, surfactants, and scale inhibitors are not used in the detergent, and the acid and base substances are also different.

[0182] The specific washing method includes three steps, which are in turn: neutral reduction complexing washing, acid washing, and alkaline slow flushing and washing.

[0183] (1) The specific process of the neutral reduction complexing washing is as follows: the detergent is circulated and washed for 30 min, soaked for 30 min, and rinsed with pure water for 30 min; the detergent for the neutral reduction complexing washing is water-based and contains 5 wt% of ethanol;

[0184] (2) The specific process of the acid washing is as follows: The detergent is circulated and washed for 30 minutes for the first time, soaked for 30 minutes, circulated and washed for 30 minutes for the second time, and rinsed with pure water until neutral; the detergent for the acid washing is water-based with a pH value of 1.5; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5 - 2.0 during the washing process.

[0185] The substances mainly used to maintain acidity in the acid washing are: a combination of hydrochloric acid and phosphoric acid in a mass ratio of 3:1.

[0186] (3) The specific process of the alkaline slow rinsing is as follows: The detergent is circulated and washed for 30 minutes for the first time, soaked for 40 minutes, circulated and washed for 10 minutes for the second time, and rinsed with pure water until neutral; the detergent for the alkaline slow rinsing is water-based with a pH value of 12; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 11 - 12 during the washing process.

[0187] The substances mainly used to maintain alkalinity in the alkaline slow rinsing are: a combination of sodium hydroxide and trisodium phosphate in a mass ratio of 3:1.

[0188] The total cleaning time of this comparative example is 320 minutes; after cleaning, mine water is used for testing, and the single - set reverse osmosis water production is 14.5 m 3 / h, and the desalination rate is 89%.

[0189] Comparative Example 2

[0190] The reverse osmosis membrane for mine water treated in this comparative example is the same as that in Example 2.

[0191] The difference between the chemical washing method of the reverse osmosis membrane for mine water treated in this comparative example and the solution of the present invention is that: the detergent for acid washing does not use surfactants and scale inhibitors; the detergent for alkaline slow rinsing does not use surfactants and scale inhibitors.

[0192] The specific washing method includes three steps, which are, in sequence: neutral reduction complexing washing, acid washing, and alkaline slow rinsing.

[0193] (1) The specific process of the neutral reduction complexing washing is as follows: The detergent is circulated and washed for 30 minutes, soaked for 30 minutes, and rinsed with pure water for 30 minutes; the detergent for the neutral reduction complexing washing is water-based and includes 5 wt% ethanol, 0.3 wt% chelate, 0.1 wt% reducing agent, and 0.4 wt% surfactant.

[0194] The chelates used are: a combination of trisodium methylglycine diacetate, tetrasodium aspartic acid diacetate, and hydroxyethanediphosphonic acid in a mass ratio of 1.5:1:1.

[0195] The reducing agent used is sodium sulfite;

[0196] The surfactants used are: alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 2:1;

[0197] (2) The specific process of the acidic washing is as follows: the detergent is circulated and washed for 30 min for the first time, soaked for 30 min, circulated and washed for 30 min for the second time, and rinsed with pure water until neutral; the detergent for the acidic washing is water-based with a pH value of 1.5; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water during the washing process at 1.5 - 2.0;

[0198] The substances mainly used to maintain acidity in the acidic washing are: hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0199] (3) The specific process of the alkaline slow rinsing is as follows: the detergent is circulated and washed for 30 min for the first time, soaked for 40 min, circulated and washed for 10 min for the second time, and rinsed with pure water until neutral; the detergent for the alkaline slow rinsing is water-based with a pH value of 12; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water during the washing process at 12;

[0200] The substances mainly used to maintain alkalinity in the alkaline slow rinsing are: sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 3:1:0.5;

[0201] The total cleaning time of this comparative example is 320 min; after cleaning, mine water is used for testing, and the single - set reverse osmosis water production is 15.5 m 3 / h, and the salt rejection rate is 91%.

[0202] Comparative Example 3

[0203] The reverse osmosis membrane for mine water treated in this comparative example is the same as that in Example 3.

[0204] The difference between the chemical washing method of the reverse osmosis membrane for mine water treated in this comparative example and the solution of the present invention is that chelating agents, reducing agents, and surfactants are not used in the detergent for the neutral reduction complex washing.

[0205] The specific washing method includes three steps, which are in sequence: neutral reduction complex washing, acidic washing, and alkaline slow rinsing.

[0206] (1) The specific process of the neutral reduction complex washing is as follows: the detergent is circulated and washed for 30 min, soaked for 30 min, and rinsed with pure water for 30 min; the detergent for the neutral reduction complex washing is water-based and contains 5 wt% ethanol;

[0207] (2) The specific process of the acid washing is as follows: the detergent is circulated and washed for the first time for 30 minutes, soaked for 30 minutes, circulated and washed for the second time for 30 minutes, and rinsed with pure water until neutral; the detergent for the acid washing is water-based, with a pH value of 1.5, and also includes 0.5 wt% of surfactant and 1 wt% of scale inhibitor; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5 - 2.0 during the washing process;

[0208] The main substances used to maintain acidity in the acid washing are: a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0209] The surfactants used are: a combination of alcohol ether carboxylate and alkyl glycoside in a mass ratio of 1:2;

[0210] The scale inhibitor used is polyacrylic acid;

[0211] (3) The specific process of the alkaline slow rinse washing is as follows: the detergent is circulated and washed for the first time for 30 minutes, soaked for 40 minutes, circulated and washed for the second time for 10 minutes, and rinsed with pure water until neutral; the detergent for the alkaline slow rinse washing is water-based, with a pH value of 12, and also includes 0.6 wt% of surfactant and 1 wt% of scale inhibitor; during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 12 during the washing process;

[0212] The main substances used to maintain alkalinity in the alkaline slow rinse washing are: a combination of sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 3:1:0.5;

[0213] The surfactants used are: a combination of alcohol ether carboxylate and alkyl glycoside in a mass ratio of 1:2;

[0214] The scale inhibitor used is acrylic acid - hydroxypropyl acrylate copolymer;

[0215] The total cleaning time of this comparative example is 320 minutes; after cleaning, mine water is used for testing, and the single - set reverse osmosis water production is 16.6 m 3 / h, and the desalination rate is 92%.

[0216] Comparative Example 4

[0217] The reverse osmosis membrane for mine water treated in this comparative example is the same as that in Example 4.

[0218] The difference between the chemical washing method of the reverse osmosis membrane for mine water treated in this comparative example and the solution of the present invention lies in the different sequence of washing procedures.

[0219] The specific washing method includes three steps, which are, in sequence: acid washing, neutral reduction complexing washing, and alkaline gentle rinsing.

[0220] (1) The specific process of the acid washing is as follows: The detergent is circulated for the first time for 30 minutes, soaked for 30 minutes, circulated for the second time for 30 minutes, and rinsed with pure water until neutral; The detergent for the acid washing is water-based, with a pH value of 1.5, and also includes 0.7 wt% of surfactant and 1 wt% of scale inhibitor; During the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5 - 2.0 during the washing process;

[0221] The main substances used to maintain acidity in the acid washing are: a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0222] The surfactants used are: a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0223] The scale inhibitor used is polyacrylic acid;

[0224] (2) The specific process of the neutral reduction complexing washing is as follows: The detergent is circulated for 30 minutes, soaked for 30 minutes, and rinsed with pure water for 30 minutes; The detergent for the neutral reduction complexing washing is water-based, including 5 wt% of ethanol, 0.2 wt% of chelate, 0.1 wt% of reducing agent, and 0.4 wt% of surfactant;

[0225] The chelates used are: a combination of tetrasodium glutamate diacetate, tetrasodium aspartate diacetate, and 1-hydroxyethylidene-1,1-diphosphonic acid in a mass ratio of 1:2:1;

[0226] The reducing agent used is sodium sulfite;

[0227] The surfactants used are: a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0228] (3) The specific process of the alkaline gentle rinsing is as follows: The detergent is circulated for the first time for 30 minutes, soaked for 40 minutes, circulated for the second time for 10 minutes, and rinsed with pure water until neutral; The detergent for the alkaline gentle rinsing is water-based, with a pH value of 11, and also includes 0.5 wt% of surfactant and 1 wt% of scale inhibitor; During the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water at 11 during the washing process;

[0229] The main substances used to maintain alkalinity in the alkaline gentle rinsing are: a combination of sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 3:1:0.5;

[0230] The surfactants used are: the combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0231] The scale inhibitor used is acrylic acid-hydroxypropyl acrylate copolymer;

[0232] The total cleaning time of this example is 320 min; after cleaning, mine water is used for testing, and the single-stage reverse osmosis water output is 17 m 3 / h, and the desalination rate is 91.5%.

[0233] Comparative Example 5

[0234] The reverse osmosis membrane of the mine water treated in this comparative example is the same as that in Example 1.

[0235] The difference between the chemical washing method of the reverse osmosis membrane for treating mine water in this comparative example and the solution of the present invention lies in the different sequence of the washing procedures.

[0236] The specific washing method includes three steps, which are in sequence: alkaline slow flushing, acid washing, and neutral reduction complexing washing.

[0237] (1) The specific process of the alkaline slow flushing is: the detergent is circulated and washed for the first time for 30 min, soaked for 40 min, circulated and washed for the second time for 10 min, and rinsed with pure water until neutral; the detergent for the alkaline slow flushing is water-based, with a pH value of 11, and also includes 0.5 wt% of surfactant and 1 wt% of scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water at 11 during the washing process;

[0238] The substances mainly used to maintain alkalinity in the alkaline slow flushing are: the combination of sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 3:1:0.5;

[0239] The surfactants used are: the combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0240] The scale inhibitor used is acrylic acid-hydroxypropyl acrylate copolymer;

[0241] (2) The specific process of the acid washing is: the detergent is circulated and washed for the first time for 30 min, soaked for 30 min, circulated and washed for the second time for 30 min, and rinsed with pure water until neutral; the detergent for the acid washing is water-based, with a pH value of 1.5, and also includes 0.6 wt% of surfactant and 1 wt% of scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water at 1.5 - 2.0 during the washing process;

[0242] The substances mainly used to maintain acidity in the acid washing are: a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0243] The surfactants used are: a combination of alcohol ether carboxylates and alkyl glycosides in a mass ratio of 1:1;

[0244] The scale inhibitor used is polyacrylic acid;

[0245] (3) The specific process of the neutral reduction complex washing is: the detergent is circulated for washing for 30 min, soaked for 30 min, and rinsed with pure water for 30 min; the detergent for the neutral reduction complex washing is water-based and includes 5 wt% ethanol, 0.2 wt% chelate, 0.1 wt% reducing agent, and 0.4 wt% surfactant;

[0246] The chelates used are: a combination of tetrasodium glutamate diacetate, trisodium methylglycine diacetate, and hydroxyethane diphosphonic acid in a mass ratio of 2:1:1;

[0247] The reducing agent used is sodium sulfite;

[0248] The surfactants used are: a combination of alcohol ether carboxylates and alkyl glycosides in a mass ratio of 1:1;

[0249] The total cleaning time of this comparative example is 320 min; after cleaning, mine water is used for testing, and the single-stage reverse osmosis water production rate is 16.5 m 3 / h, and the desalination rate is 92%.

[0250] Comparative Example 6

[0251] The reverse osmosis membrane of the mine water treated in this comparative example is the same as that in Example 2.

[0252] The difference between the chemical washing method of the reverse osmosis membrane for treating mine water in this comparative example and the solution of the present invention lies in the different order of the washing procedures.

[0253] The specific washing method includes three steps, which are, in sequence: alkaline slow flushing, neutral reduction complex washing, and acid washing.

[0254] (1) The specific process of the alkaline slow flushing is: the detergent is circulated for the first time for washing for 30 min, soaked for 40 min, circulated for the second time for washing for 10 min, and rinsed with pure water until neutral; the detergent for the alkaline slow flushing is water-based, with a pH value of 12, and also includes 0.6 wt% surfactant and 1 wt% scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to keep the pH value of the washing water during the washing process at 11-12;

[0255] The substances mainly used to maintain alkalinity in the alkaline flushing and washing are a combination of sodium hydroxide, trisodium phosphate, and sodium citrate at a mass ratio of 3:1:0.5;

[0256] The surfactants used are a combination of alcohol ether carboxylate and alkyl polyglycoside at a mass ratio of 2:1;

[0257] The scale inhibitor used is an acrylic acid - hydroxypropyl acrylate copolymer;

[0258] (2) The specific process of the neutral reduction complex washing is as follows: The detergent is circulated for washing for 30 minutes, soaked for 30 minutes, and rinsed with pure water for 30 minutes; The detergent for the neutral reduction complex washing is water - based and includes 5 wt% ethanol, 0.3 wt% chelating agent, 0.1 wt% reducing agent, and 0.3 wt% surfactant;

[0259] The chelating agent used is a combination of trisodium methylglycine diacetate, tetrasodium aspartic acid diacetate, and hydroxyethane diphosphonic acid at a mass ratio of 1.5:1:1;

[0260] The reducing agent used is sodium sulfite;

[0261] The surfactants used are a combination of alcohol ether carboxylate and alkyl polyglycoside at a mass ratio of 2:1;

[0262] (3) The specific process of the acidic washing is as follows: The detergent is circulated for the first time for washing for 30 minutes, soaked for 30 minutes, circulated for the second time for washing for 30 minutes, and rinsed with pure water until neutral; The detergent for the acidic washing is water - based, with a pH value of 1.5, and also includes 0.8 wt% surfactant and 1 wt% scale inhibitor; During the two - cycle washing process, the detergent needs to be continuously updated to keep the pH value of the washing water during the washing process between 1.5 and 2.0;

[0263] The substances mainly used to maintain acidity in the acidic washing are a combination of hydrochloric acid, phosphoric acid, and citric acid at a mass ratio of 3:1:1;

[0264] The surfactants used are a combination of alcohol ether carboxylate and alkyl polyglycoside at a mass ratio of 2:1;

[0265] The scale inhibitor used is polyacrylic acid;

[0266] The total cleaning time of this comparative example is 320 minutes; After cleaning, mine water is used for testing. The single - set reverse osmosis water production is 17 m 3 / h, and the desalination rate is 92.5%.

[0267] Comparative Example 7

[0268] The reverse osmosis membrane of the mine water treated in this comparative example is the same as that in Example 3.

[0269] The difference between the chemical washing method of the reverse osmosis membrane for treating mine water in this comparative example and the solution of the present invention is that only acid washing is carried out in this comparative example. The washing time and detergent are also different.

[0270] The specific steps are as follows: The detergent is circulated and washed for the first time for 60 minutes, soaked for 60 minutes, circulated and washed for the second time for 60 minutes, and rinsed with pure water until neutral; the detergent for the acid washing is water-based, with a pH value of 1.5, and also includes 0.8 wt% of EDTA (ethylenediaminetetraacetic acid); during the two cycles of washing, the detergent needs to be continuously updated to maintain the pH value of the washing water during the washing process at 1.5 - 2.0;

[0271] The substances mainly used to maintain acidity in the acid washing are: a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0272] The total cleaning time of this comparative example is 320 minutes; after cleaning, it is tested with mine water, and the single - set reverse osmosis water production is 11 m 3 / h, and the desalination rate is 88%.

[0273] Comparative Example 8

[0274] The reverse osmosis membrane for treating mine water in this comparative example is the same as that in Example 4.

[0275] In this comparative example, acid washing and alkaline washing are successively used to repeat chemical washing of a brand - new reverse osmosis membrane 5 times. The acid detergent is hydrochloric acid, and the pH value is controlled at 2.0 during the washing process. The alkaline detergent is sodium hydroxide, and the pH value is controlled at 11.5 during the washing process.

[0276] The specific process of the acid washing is as follows: The detergent is circulated and washed for the first time for 30 minutes, soaked for 30 minutes, circulated and washed for the second time for 30 minutes, and rinsed with pure water until neutral.

[0277] The specific process of the alkaline slow - rinse washing is as follows: The detergent is circulated and washed for the first time for 30 minutes, soaked for 40 minutes, circulated and washed for the second time for 10 minutes, and rinsed with pure water until neutral.

[0278] The cleaning time for each time in this comparative example is 230 minutes, and it is circulated 5 times. The total cleaning time is 1150 minutes. After cleaning, it is tested with mine water, and the single - set reverse osmosis water production is 18.5 m 3 / h, and the desalination rate is 89.2%.

[0279] Comparative Example 9

[0280] The reverse osmosis membrane for treating mine water in this comparative example is the same as that in Example 4.

[0281] The difference between the chemical washing method of the reverse osmosis membrane for treating mine water in this comparative example and the solution of the present invention lies in the different sequence of the washing procedures. In this comparative example, alkaline slow flushing, neutral reduction complexing washing, and acidic washing are successively used to repeat the chemical washing of a brand-new reverse osmosis membrane 5 times. The specific process is as follows:

[0282] (1) The specific process of the alkaline slow flushing is as follows: The detergent is circulated and washed for 30 minutes for the first time, soaked for 40 minutes, circulated and washed for 10 minutes for the second time, and rinsed with pure water until neutral; the detergent for the alkaline slow flushing is water-based, with a pH value of 12, and also includes 0.6 wt% of surfactant and 1 wt% of scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water during the washing process at 11 - 12;

[0283] The substances mainly used to maintain alkalinity in the alkaline slow flushing are: a combination of sodium hydroxide, trisodium phosphate, and sodium citrate in a mass ratio of 3:1:0.5;

[0284] The surfactant used is: a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0285] The scale inhibitor used is acrylic acid - hydroxypropyl acrylate copolymer;

[0286] (2) The specific process of the neutral reduction complexing washing is as follows: The detergent is circulated and washed for 30 minutes, soaked for 30 minutes, and rinsed with pure water for 30 minutes; the detergent for the neutral reduction complexing washing is water-based, including 5 wt% of ethanol, 0.3 wt% of chelating agent, 0.1 wt% of reducing agent, and 0.3 wt% of surfactant;

[0287] The chelating agent used is: a combination of tetrasodium glutamate diacetate, tetrasodium aspartate diacetate, and hydroxyethane diphosphonic acid in a mass ratio of 1:2:1;

[0288] The reducing agent used is sodium sulfite;

[0289] The surfactant used is: a combination of alcohol ether carboxylate and alkyl polyglycoside in a mass ratio of 1:1;

[0290] (3) The specific process of the acidic washing is as follows: The detergent is circulated and washed for 30 minutes for the first time, soaked for 30 minutes, circulated and washed for 30 minutes for the second time, and rinsed with pure water until neutral; the detergent for the acidic washing is water-based, with a pH value of 1.5, and also includes 0.5 wt% of surfactant and 1 wt% of scale inhibitor; during the two circulation washing processes, the detergent needs to be continuously updated to maintain the pH value of the washing water during the washing process at 1.5 - 2.0;

[0291] The substances mainly used to maintain acidity in the acid washing are: a combination of hydrochloric acid, phosphoric acid, and citric acid in a mass ratio of 3:1:1;

[0292] The surfactants used are: a combination of alcohol ether carboxylate and alkyl glycoside in a mass ratio of 1:1;

[0293] The scale inhibitor used is polyacrylic acid;

[0294] The cleaning time for each time in this comparative example is 320 min, and the total cleaning time is 1600 min; after cleaning, mine water is used for testing, and the single - set reverse osmosis water production is 19.5 m 3 / h, and the desalination rate is 90.2%.

[0295] Reference Example

[0296] The reverse osmosis membrane of the mine water treated in this reference example is the same as that in Example 4.

[0297] In this reference example, deionized water is used as the detergent throughout the process to wash the brand - new reverse osmosis membrane. According to the processes of cyclic washing, soaking, rinsing, etc. in Example 4, the total cleaning time for each time is 320 min, and the washing is repeated 5 times. After cleaning, mine water is used for testing, and the single - set reverse osmosis water production is 20.0 m 3 / h, and the desalination rate is 99.2%.

[0298] Table 1 Filtration effects of reverse osmosis membranes after cleaning in each case

[0299]

[0300] It can be seen from Table 1 by comparison that for the reverse osmosis membranes that have been used with mine water, in Examples 1 - 3 of the present invention, both the single - set reverse osmosis water production and the desalination rate after cleaning are significantly better than those in Comparative Examples 1 - 7, significantly slowing down the performance decay of the reverse osmosis membrane. The cleaning tests of the brand - new reverse osmosis membrane in Example 4, Comparative Example 8, Comparative Example 9, and the Reference Example further demonstrate that the cleaning method of the present invention has the advantage of less damage to the reverse osmosis membrane compared with other similar cleaning methods, and can effectively extend the service life of the reverse osmosis membrane.

Claims

1. A chemical washing method for a reverse osmosis membrane for treating mining water, characterized in that: Including neutral reduction complex washing, acid washing and alkaline buffer washing; The processes of neutral reduction complex washing, acid washing and alkaline buffer washing respectively include: detergent circulation washing, detergent soaking and clean water rinsing; The neutral reduction complex washing detergent is water-based and includes alcohol, chelate, reducing agent and surfactant; in the neutral reduction complex washing detergent, the concentration of alcohol is 2wt% to 10wt%, the concentration of chelate is 0.1wt% to 1wt%, the concentration of reducing agent is 0.05wt% to 0.5wt%, and the concentration of surfactant is 0.1wt% to 1wt%; The acidic washing detergent is water-based, has a pH value of 1.5 to 2.0, and also includes a surfactant and an antiscalant; in the acidic washing detergent, the concentration of the surfactant is 0.1 wt% to 1 wt%, and the concentration of the antiscalant is 0.3 wt% to 2 wt%; The alkaline buffer washing detergent is water-based, has a pH value of 11-12, and also includes a surfactant and a scale inhibitor; in the alkaline buffer washing detergent, the concentration of the surfactant is 0.1wt%-1wt%, and the concentration of the scale inhibitor is 0.3wt%-2wt%.

2. The chemical washing method for reverse osmosis membrane for treating mine water according to claim 1, characterized in that: In the neutral reduction complex washing detergent, the concentration of alcohol is 4wt% to 6wt%; In the detergent for neutral reduction complex washing, the concentration of chelate is 0.2wt% to 0.4wt%; In the neutral reduction complex washing detergent, the reducing agent concentration is 0.1wt% to 0.2wt%; In the neutral reduction complex washing detergent, the surfactant concentration is 0.3wt% to 0.5wt%; In the acidic washing detergent, the surfactant concentration is 0.5wt% to 0.8wt%; In the acid washing detergent, the concentration of the scale inhibitor is 0.8wt% to 1.2wt%; In the detergent for alkaline buffer washing, the surfactant concentration is 0.5wt% to 0.8wt%; In the detergent for alkaline buffer washing, the concentration of the scale inhibitor is 0.8 wt % to 1.2 wt %.

3. The chemical washing method for reverse osmosis membrane for treating mine water according to claim 1, characterized in that: The neutral reduction complex washing process includes: detergent circulation washing, detergent soaking, and clean water rinsing; The acid washing process includes: first cycle washing with detergent, detergent soaking, second cycle washing with detergent, and clean water rinsing; The alkaline buffer washing process includes: a first cycle washing with detergent, a detergent soaking, a second cycle washing with detergent, and a clean water rinse; The cycle washing time of the neutral reduction complex washing is 25min to 35min; The immersion time of the neutral reduction complex washing is 25min to 35min; After the neutral reduction complex washing is completed, rinse with water for 25 minutes to 35 minutes; The first cycle washing time of the acid washing is 25 to 35 minutes; The soaking time of the acid washing is 25 to 35 minutes; The second cycle washing time of the acid washing is 25 to 35 minutes; The first cycle washing time of the alkaline buffer washing is 25min to 35min; The immersion time of the alkaline buffer washing is 35min to 45min; The second cycle washing time of the alkaline buffer washing is 8 minutes to 12 minutes.

4. The chemical washing method for a reverse osmosis membrane for treating mining water according to any one of claims 1 to 3, characterized in that: In the detergent for neutral reduction complex washing, the alcohol includes ethanol; In the neutral reduction complex washing detergent, the chelate includes two or more of tetrasodium glutamate diacetate, trisodium methylglycine diacetate, tetrasodium aspartate diacetate, and etidronic acid; In the detergent for neutral reduction complex washing, the reducing agent includes sodium sulfite; In the neutral reduction complex washing detergent, the surfactant includes alcohol ether carboxylate and alkyl glycoside.

5. The chemical washing method for a reverse osmosis membrane for treating mining water according to any one of claims 1 to 3, characterized in that: In the acidic washing detergent, the acid includes hydrochloric acid, phosphoric acid and citric acid; In the acidic washing detergent, the surfactant includes alcohol ether carboxylates and alkyl glycosides; In the acidic washing detergent, the scale inhibitor includes polyacrylic acid.

6. The chemical washing method for reverse osmosis membrane for treating mining water according to claim 5, characterized in that: In the acidic washing detergent, the mass ratio of hydrochloric acid, phosphoric acid and citric acid is 2.5-3.5:0.8-1.2:

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7. The chemical washing method for a reverse osmosis membrane for treating mining water according to any one of claims 1 to 3, characterized in that: In the detergent for the alkaline buffered washing, the alkali includes sodium hydroxide, trisodium phosphate and sodium citrate; In the detergent for alkaline buffer washing, the surfactant includes alcohol ether carboxylates and alkyl glycosides; In the detergent for alkaline buffer washing, the scale inhibitor includes acrylic acid-hydroxypropyl acrylate copolymer.

8. The chemical washing method for reverse osmosis membrane for treating mining water according to claim 7, characterized in that: In the detergent for alkaline buffer washing, the mass ratio of sodium hydroxide, trisodium phosphate and sodium citrate is 5-8:1.6-2.2:

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9. The method for chemically washing a reverse osmosis membrane for treating mining water according to any one of claims 1 to 3, characterized in that: After the acid washing is completed, the reverse osmosis membrane is rinsed with water until it becomes neutral; During the two cycles of acid washing, the pH value of the washing process is maintained at 1.5 to 2.0 by renewing the detergent; After the alkaline buffer washing is completed, the reverse osmosis membrane is rinsed with water until it is neutral; During the two cycles of alkaline buffer washing, the pH value during the washing process is maintained at 11-12 by refreshing the detergent.

10. The chemical washing method for a reverse osmosis membrane for treating mining water according to any one of claims 1 to 3, characterized in that: The mine water contains one or more of copper, cobalt, iron, aluminum and manganese; The separation layer of the reverse osmosis membrane is made of polyamide; the pore size of the reverse osmosis membrane is less than 0.020 μm.

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