Polyester reverse osmosis membrane organic pollution cleaning method

Abstract

The invention discloses a method for cleaning organic pollution of a polyester reverse osmosis membrane. The method comprises the following steps: (a) flushing the reverse osmosis membrane with pure water; (b) mixing sodium bicarbonate and fatty alcohol-polyoxyethylene ether to form a mixed cleaning solution, and cleaning the reverse osmosis membrane cleaned in the step (a) with the mixed cleaning solution; (c) flushing the reverse osmosis membrane cleaned in the step (b) with pure water until the reverse osmosis membrane is neutral; (d) cleaning the reverse osmosis membrane cleaned in the step (c) by using an ethylenediamine tetraacetic acid disodium solution; (e) flushing the reverse osmosis membrane cleaned in the step (d) with pure water until the reverse osmosis membrane is neutral; (f) cleaning the reverse osmosis membrane cleaned in the step (e) with a malic acid solution; and (g) flushing the reverse osmosis membrane cleaned in the step (f) with pure water until the reverse osmosis membrane is neutral. According to the invention, pollutants can be efficiently, stably, comprehensively and mildly cleaned.

Description

Technical Field

[0001] The invention relates to water treatment equipment, more specifically, to a polyester reverse osmosis membrane and also to a method for cleaning organic pollution of the polyester reverse osmosis membrane. Background Art

[0002] In the wide application of modern membrane separation technology, polyester reverse osmosis membrane has been widely used in many fields due to its unique chemical stability, good mechanical strength and suitable hydrophilicity, especially in the treatment of industrial wastewater with high salinity and coexistence of complex organic pollutants and specific chemical separation processes. However, it inevitably faces severe challenges of organic pollution during operation.

[0003] Although the good hydrophilicity of polyester reverse osmosis membrane makes it more resistant to pollution than other reverse osmosis membranes, for wastewater rich in organic pollutants such as bovine serum albumin, oils and fats, and various polysaccharides, pollutants are still easily adsorbed and deposited on the surface of polyester reverse osmosis membrane. Related studies have shown that in some chemical wastewater treatment scenarios, after a period of operation, the flux of polyester reverse osmosis membrane can be reduced by 40% to 60%, seriously affecting the separation efficiency and service life of the membrane.

[0004] The current commonly used membrane cleaning methods often fail to fully consider the characteristics of polyester materials when dealing with organic contamination of polyester reverse osmosis membranes, resulting in unsatisfactory cleaning effects or damage to the membrane structure. Some strongly alkaline or strongly oxidizing cleaning agents may cause the breakage or hydrolysis of polyester molecular chains, reducing the mechanical properties and chemical stability of the membrane.

[0005] Therefore, a new solution is needed to solve the cleaning problem of organic pollution of polyester reverse osmosis membrane. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a method for cleaning organic contamination of a polyester reverse osmosis membrane and a polyester reverse osmosis membrane.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for cleaning organic pollution of a polyester reverse osmosis membrane comprises the following steps:

[0009] (a) flushing the reverse osmosis membrane with pure water;

[0010] (b) using sodium bicarbonate and fatty alcohol polyoxyethylene ether to form a mixed cleaning solution, and using the mixed cleaning solution to clean the reverse osmosis membrane after cleaning in step (a);

[0011] (c) flushing the reverse osmosis membrane after cleaning in step (b) with pure water until it becomes neutral;

[0012] (d) cleaning the reverse osmosis membrane after cleaning in step (c) with a disodium ethylenediaminetetraacetic acid solution;

[0013] (e) flushing the reverse osmosis membrane after cleaning in step (d) with pure water until it becomes neutral;

[0014] (f) cleaning the reverse osmosis membrane after cleaning in step (e) with a malic acid solution;

[0015] (g) Rinse the reverse osmosis membrane cleaned in step (f) with pure water until it becomes neutral.

[0016] The present invention is further configured such that, in step (a), pure water is flushed at a flow rate of 80 to 120 L / h for 10 to 20 minutes.

[0017] The present invention is further configured such that in step (b), the mixed cleaning solution is formed by mixing 0.03wt% to 0.07wt% of sodium bicarbonate and 0.04wt% to 0.08wt% of fatty alcohol polyoxyethylene ether.

[0018] The present invention is further configured such that in step (b), the mixed cleaning liquid is first cleaned at a flow rate of 100-150 L / h for 15-25 min, then cleaned at a flow rate of 200-250 L / h for 15-25 min, and then the cleaning liquid is placed in the reverse osmosis membrane and maintained at a standstill for at least 10 min.

[0019] The present invention is further configured that, in step (d), the concentration of the disodium ethylenediaminetetraacetic acid solution is 0.02wt% to 0.06wt%.

[0020] The present invention is further configured such that in step (d), the disodium ethylenediaminetetraacetic acid solution is first cleaned at a flow rate of 120 to 200 L / h for 20 to 30 minutes, and then the cleaning solution is placed in the reverse osmosis membrane and maintained at rest for at least 10 minutes.

[0021] The present invention is further configured such that, in step (f), the concentration of the malic acid solution is 0.8 wt % to 1.2 wt %.

[0022] The present invention is further configured such that, in step (f), the malic acid solution is cleaned at a flow rate of 100 to 150 L / h for 15 to 25 minutes.

[0023] The present invention also provides a polyester reverse osmosis membrane, and the polluted reverse osmosis membrane is cleaned by using the above-mentioned polyester reverse osmosis membrane organic pollution cleaning method.

[0024] The present invention also provides a polyester reverse osmosis membrane, comprising a tube shell and a reverse osmosis membrane assembly, wherein the reverse osmosis membrane assembly is installed in the tube shell, a water inlet cavity is formed at the lower side of the reverse osmosis membrane assembly, and a concentrated water cavity is formed at the upper side;

[0025] The reverse osmosis membrane assembly comprises a central tube that passes through from top to bottom, the central tube is coaxially fixedly installed in a tube shell, and a reverse osmosis membrane material is wound and coated between the outer periphery of the central tube and the inner cavity wall of the tube shell; the central tube is provided with a plurality of through holes that pass through the inner and outer peripheries, and the through holes are covered by the reverse osmosis membrane material;

[0026] The water production pipe is arranged in the central pipe, and is provided with a plurality of through holes 2 penetrating the inner and outer axes, and the through holes 2 correspond to the through holes one by one;

[0027] An adjusting rod is coaxially passed through the water production pipe, a piston is fixedly installed on the outer periphery of the adjusting rod, and the outer periphery of the piston is connected to the inner periphery of the water production pipe by a piston; the piston is provided with a plurality of flow guide holes which pass through the upper and lower parts, and a one-way flow limiting part is installed on the piston part, and the one-way flow limiting part realizes one-way conduction upwards by using the corresponding flow guide holes.

[0028] The polyester reverse osmosis membrane can be used to push the cleaning liquid in the polyester reverse osmosis membrane back during the cleaning process, mainly when the cleaning liquid is stationary, to adjust the flow direction of the cleaning liquid. Through forward and reverse circulation, it can effectively shear and impact the membrane surface, and partially remove and dissolve the pollutants on the membrane surface during the static process. Flushing and cleaning can improve the cleaning effect of the membrane material. The cleaning liquid can clean the corners inside the membrane material, further improving the cleaning effect during the static process.

[0029] In summary, the present invention has the following beneficial effects:

[0030] The cleaning method of the present invention has efficient flux recovery performance. After cleaning, the flux recovery rate of the polyester reverse osmosis membrane can reach more than 90%. In multiple experiments and actual application cases, the flux recovery rate of some membranes can even reach 93% to 95%, which has a significant flux recovery effect, greatly improves the performance recovery degree of the membrane, and effectively extends the service life of the membrane. Compared with the traditional cleaning process, the membrane replacement cycle can be extended by 2 to 3 times, which significantly reduces the membrane replacement cost and operation and maintenance costs, and brings significant economic benefits to the enterprise.

[0031] The cleaning method of the present invention has better membrane compatibility and stability. Compared with the traditional cleaning method, the cleaning process is highly compatible with polyester reverse osmosis membranes and can effectively protect the chemical structure and physical properties of the membrane during the cleaning process. By avoiding damage to the polyester molecular chain and maintaining the mechanical strength of the membrane, the long-term stable operation of the membrane under complex water conditions is ensured, the system downtime caused by membrane failure is reduced, the production efficiency is improved, and the reliability and stability of the enterprise's production operation are enhanced.

[0032] The cleaning method of the present invention has comprehensive pollutant removal capabilities. The cleaning method has a strong removal capability for a variety of organic pollutants, including proteins, polysaccharides, oils, and their composite pollutants, and can completely remove the organic pollution layer on the membrane surface and in the pores, effectively restore the interception performance and flux characteristics of the membrane, ensure that the effluent water quality of the membrane treatment system is stable and up to standard, improve the application efficiency and competitiveness of polyester reverse osmosis membrane technology in the field of water treatment, and is of great significance to promoting technological progress in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the three-dimensional structure of a polyester reverse osmosis membrane in the embodiment;

[0034] Figure 2 is a three-dimensional cross-sectional view of a polyester reverse osmosis membrane in an embodiment;

[0035] Figure 3 is a cross-sectional view of a polyester reverse osmosis membrane in an embodiment;

[0036] Figure 4 Schematic diagram of the structure of the water production pipe and the reverse osmosis membrane assembly in the embodiment;

[0037] Figure 5 is a cross-sectional view of the lower end of the water production pipe in the embodiment;

[0038] Figure 6 It is a schematic diagram of the structure of the water production pipe, the piston member and the one-way flow limiting member in the embodiment;

[0039] Figure 7 Schematic diagram of the backflow between the water production pipe and the reverse osmosis membrane assembly in the embodiment.

[0040] Figure 8 Schematic diagram of the structure of the connecting joint in the embodiment.

[0041] Figure numerals: tube shell 1; end cover 101; end cover 2 102; water inlet chamber 103; concentrate chamber 104; partition chamber 105; connecting joint 200; water production interface 201; water inlet pipe 2; water production pipe 3; through hole 2 31; support frame 32; outer retaining ring 1 33; reflux hole 34; lower port 35; inner retaining ring 36; conical surface 1 37; outer retaining ring 2 38; concentrate pipe 4; reverse osmosis membrane assembly 5; splicing section 50; center pipe 51; through hole 1 511; end plate 52; water passage hole 53; reverse osmosis membrane material 54; adjusting rod 6; spring 1 7; plug 8; conical surface 2 81; connecting hole 82; spring 2 83; piston member 9; guide hole 91; one-way flow limiting member 92; inner peripheral portion 921; outer peripheral portion 922. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] This embodiment discloses a method for cleaning organic contamination of a polyester reverse osmosis membrane, comprising the following steps:

[0044] (a) Rinse the reverse osmosis membrane with pure water at a flow rate of 80 to 120 L / h for 10 to 20 minutes. This step uses the mechanical shear force of the water flow to preliminarily remove organic pollutants and some impurities loosely attached to the membrane surface, while reducing the load of subsequent chemical cleaning and helping to protect the membrane surface from direct impact of subsequent chemical agents.

[0045] (b) 0.03wt% to 0.07wt% of sodium bicarbonate and 0.04wt% to 0.08wt% of fatty alcohol polyoxyethylene ether are mixed to form a mixed cleaning liquid, and the reverse osmosis membrane after cleaning in step (a) is cleaned with the mixed cleaning liquid; first, the cleaning is carried out at a flow rate of 100 to 150L / h for 15 to 25min, so that the agent is fully in contact with the organic pollutants on the membrane surface; then, the cleaning is carried out at a flow rate of 200 to 250L / h for 15 to 25min, and the flow rate is increased to increase its mechanical shear force, so that the pollutants loosened by the initial cleaning but not washed away are further detached or dissolved in the cleaning liquid; then, the cleaning liquid is placed in the reverse osmosis membrane, and maintained at a standstill for at least 10min to fully dissolve the pollutants on the surface of the membrane and the detached pollutants, so as to further achieve a cleaning effect. Sodium bicarbonate, as a relatively mild alkaline substance, can weakly hydrolyze some organic pollutants without seriously affecting the polyester structure, while fatty alcohol polyoxyethylene ether uses its good surface activity to reduce the adhesion between the pollutants and the membrane surface.

[0046] (c) Rinse the reverse osmosis membrane after cleaning in step (b) with pure water until it becomes neutral, ensuring that the chemical agents remaining on the membrane surface are completely removed to avoid affecting the effect of the next stage of cleaning.

[0047] (d) cleaning the reverse osmosis membrane after cleaning in step (c) with a 0.02wt% to 0.06wt% disodium ethylenediaminetetraacetic acid solution; first, cleaning at a flow rate of 120 to 200 L / h for 20 to 30 minutes, and then placing the cleaning solution in the reverse osmosis membrane for at least 10 minutes; disodium ethylenediaminetetraacetic acid can effectively complex metal ions that may be adsorbed on the membrane surface to prevent them from promoting the interaction between organic pollutants and the membrane surface, and further assist in removing some organic pollutants.

[0048] (e) Rinse the reverse osmosis membrane cleaned in step (d) with pure water until it becomes neutral, ensuring that the chemical agents remaining on the membrane surface are completely removed to avoid affecting the effect of the next stage of chemical cleaning.

[0049] (f) cleaning the reverse osmosis membrane after cleaning in step (e) with a 0.8wt% to 1.2wt% malic acid solution; cleaning at a flow rate of 100 to 150 L / h for 15 to 25 minutes; malic acid has strong acidity and good complexing ability, and can effectively remove inorganic salt crystals, metal ions and other difficult-to-remove organic pollutants remaining on the membrane surface, achieve deep purification of the membrane surface, and restore the flux and retention performance of the membrane.

[0050] (g) Rinse the reverse osmosis membrane after cleaning in step (f) with pure water until it becomes neutral, ensuring that the chemical agents remaining on the membrane surface are completely removed to prevent adverse effects on membrane performance and keep the membrane in optimal operating condition.

[0051] Among them, the pure water flushing in step (a) is based on the principles of fluid mechanics. By controlling the appropriate clean water flow rate and flushing time, the shear force and scouring effect of the water flow are used to remove loose pollutants and impurities on the membrane surface, while avoiding mechanical damage to the membrane structure, creating favorable conditions for subsequent chemical cleaning.

[0052] In step (b), sodium bicarbonate NaHCO3 and fatty alcohol polyoxyethylene ether AEO work synergistically. Sodium bicarbonate NaHCO3 provides a weak alkaline environment in the solution, and carbonate and hydroxide ions generated by its hydrolysis can react with certain functional groups in organic pollutants, causing the organic pollutants to decompose into smaller molecular fragments. The surface activity of fatty alcohol polyoxyethylene ether AEO reduces the interfacial tension between the pollutants and the membrane surface through the hydrophilic and hydrophobic groups in its molecular structure, making it easier for the pollutants to detach from the membrane surface. The synergistic effect of the two realizes the initial removal of organic pollutants.

[0053] Among them, in step (d), the EDTA-2Na disodium complexing reaction, multiple carboxyl groups and amino groups in the EDTA-2Na disodium molecule can form a stable complex with the metal ions adsorbed on the membrane surface, thereby destroying the promoting effect of the metal ions on the interaction between the organic pollutants and the membrane surface. At the same time, the local environment may change during the complexing process, which is helpful to further decompose and remove some organic pollutants.

[0054] Among them, in step (d), the EDTA-2Na solution cleaning step takes into account the potential impact of microbial contamination in membrane contamination, and a composite fungicide extracted from natural plants can be added. The composite fungicide is composed of a variety of plant active ingredients, such as tea tree essential oil, thyme extract, etc., and has a broad-spectrum antibacterial property. Specifically, one of tea tree essential oil and thyme extract or a mixture of the two can be used.

[0055] On the one hand, it can effectively kill microorganisms on the membrane surface and in the pores, prevent microorganisms from growing and forming biofilms, and reduce the adsorption and fixation of microorganisms on organic pollutants, thereby indirectly enhancing the removal effect of organic pollutants; on the other hand, natural ingredients have good compatibility with polyester reverse osmosis membranes and will not damage the membrane structure like some traditional chemical fungicides, thus ensuring the chemical stability and mechanical strength of the membrane. There is a synergistic effect between the composite fungicide and EDTA-2Na disodium. While chelating metal ions, EDTA-2Na disodium will change the microenvironment on the membrane surface, making it easier for the composite fungicide to penetrate into the deep structure of the membrane and exert its antibacterial effect. At the same time, after the composite fungicide kills microorganisms, the microbial cell structure is destroyed, and the released organic components are more easily removed by subsequent cleaning agents, further improving the comprehensive removal ability of the cleaning process for organic pollutants and microbial pollution.

[0056] Among them, if the inorganic pollution of the membrane in step (f) is serious, the cleaning time can be appropriately increased or the membrane can be cleaned according to the cleaning method of "0.03wt% to 0.07wt% sodium bicarbonate NaHCO3 and 0.04wt% to 0.08wt% fatty alcohol polyoxyethylene ether AEO mixed solution for cleaning", which can effectively achieve the cleaning of fine parts. The acidic environment of malic acid can further hydrolyze or decompose the residual organic pollutants, and the carboxyl groups in its molecules can form complexes with metal ions and inorganic salt crystals, and these pollutants are removed from the membrane surface under the action of water flow, achieving deep purification of the membrane surface and performance recovery.

[0057] Among them, in each step, the cleaning reagent adopts different cleaning flow rates and different cleaning times, or adopts the cleaning mode of "small flow cleaning + large flow cleaning + standing". The cleaning mode from slow to fast and then to slow again helps to deeply clean the attached pollutants without damaging the polyester layer structure of the membrane.

[0058] Among them, in each step, a mode of first discharging the cleaning liquid and then circulating it can be adopted. In the current step, the cleaning liquid of this step is first introduced to flush out all the cleaning liquid of the previous step, which is conducive to the effect of the cleaning liquid.

[0059] By selecting chemical agents such as NaHCO3, AEO, EDTA-2Na and malic acid, a highly efficient cleaning system for organic pollution of polyester reverse osmosis membrane is formed within a specific concentration range. It can effectively and gently tilt the polyester reverse osmosis membrane, ensuring the cleaning effect while ensuring the safety of the membrane structure and extending the effective service life of the membrane material.

[0060] During the cleaning process, the dynamic and rapid adjustment of the cleaning liquid in the membrane, combined with static stillness, can effectively and deeply dissolve the pollutants in the cleaning liquid, effectively ensuring the clean cleaning of the membrane.

[0061] Combined with the chemical structure and physical properties of polyester reverse osmosis membrane, the above process flow and cleaning reagent can effectively clean the polyester material, ensuring that while achieving efficient cleaning, damage to the membrane structure is avoided to the greatest extent, ensuring the long-term stable operation of the membrane. The cleaning method of this embodiment can also be applied to the wastewater zero discharge process of separating inorganic salts from high-salt printing and dyeing wastewater and reusing it in the form of solution.

[0062] Specifically, the cleaning method in this embodiment and the methods of the other three comparative examples were used to clean and compare the polluted polyester reverse osmosis membrane.

[0063] The polyester reverse osmosis membrane used has an original pure water flux of 52LMH. Under standard conditions, the retention rate of the polyester reverse osmosis membrane with 2000mg / LNaCl as the test liquid is 99.37%. After running with industrial wastewater (simulated industrial wastewater can be used, which is a mixture of bovine serum albumin, oils and fats, various polysaccharides and various inorganic salts), the flux drops to 35LMH and the retention rate is 99.21%.

[0064] The preferred embodiments of the present invention are as follows:

[0065] Example 1

[0066] The cleaning steps of this embodiment are:

[0067] (a) flushing the reverse osmosis membrane with pure water at a flow rate of 120 L / h for 15 min;

[0068] (b) using 0.05 wt % sodium bicarbonate and 0.05 wt % fatty alcohol polyoxyethylene ether to form a mixed cleaning solution, and using the mixed cleaning solution to clean the reverse osmosis membrane after cleaning in step (a); first cleaning at a flow rate of 120 L / h for 25 min to allow the agent to fully contact the organic pollutants on the membrane surface; and then cleaning at a flow rate of 220 L / h for 25 min;

[0069] (c) flushing the reverse osmosis membrane after cleaning in step (b) with pure water until it becomes neutral;

[0070] (d) cleaning the reverse osmosis membrane after cleaning in step (c) with a 0.04 wt % disodium ethylenediaminetetraacetic acid solution; first, cleaning at a flow rate of 200 L / h for 25 min, and then leaving the cleaning solution in the reverse osmosis membrane for at least 10 min;

[0071] (e) flushing the reverse osmosis membrane after cleaning in step (d) with pure water until it becomes neutral;

[0072] (f) cleaning the reverse osmosis membrane after cleaning in step (e) with a 1.0 wt % malic acid solution; cleaning at a flow rate of 120 L / h for 25 min;

[0073] (g) flushing the reverse osmosis membrane after cleaning in step (f) with pure water until it becomes neutral, so that the reverse osmosis membrane can be cleaned and is in the best operating state.

[0074] Comparative Example 1

[0075] The steps of comparative cleaning scheme 1 are: first, the contaminated membrane is preliminarily rinsed with pure water at a clean water flow rate of 120 L / h for 15 minutes; then, 1.5wt% citric acid is used to clean for 25 minutes at a flow rate of 220 L / h; finally, it is rinsed with clean water until it is neutral to put the membrane in the best operating state.

[0076] Comparative Example 2

[0077] The cleaning steps of Comparative Example 2 are: first, the contaminated membrane is preliminarily rinsed with pure water at a clean water flow rate of 120L / h for 15 minutes; then, it is cleaned with 0.1wt% sodium hydroxide + 0.025wt% sodium dodecylbenzene sulfonate for 25 minutes; finally, it is rinsed with clean water until neutral to put the membrane in the best operating state.

[0078] Comparative Example 3

[0079] The cleaning steps of Comparative Example 3 are: first, the contaminated membrane is preliminarily rinsed with pure water at a clean water flow rate of 120L / h for 15min; then, it is cleaned with a mixed solution of 0.1wt% sodium hydroxide + 0.025wt% sodium dodecylbenzene sulfonate, first cleaning at a flow rate of 120L / h for 25min to allow the agent to fully contact the pollutant, and then cleaning at a flow rate of 220L / h for 25min to increase the mechanical shear force, and then standing for more than 10min to fully dissolve the pollutants; then rinse with pure water to neutrality to ensure that residual agents are removed; then clean with 2.0wt% hydrochloric acid solution at a flow rate of 120L / h for 25min; finally, rinse with clean water to neutrality to put the membrane in the best operating state.

[0080] The cleaning effects of the four methods on the polyester reverse osmosis membrane are shown in Table 1. The scheme of the present invention has an excellent cleaning effect on the contaminated polyester reverse osmosis membrane, and achieves good recovery of the membrane flux and interception performance while ensuring that the structure of the membrane itself is not damaged.

[0081] Table 1 Changes in membrane retention rate after cleaning with different cleaning schemes

[0082] plan Flux after cleaning / LMH Flux recovery rate / % Retention rate after cleaning / % Retention rate recovery rate / % Solution of the present invention 47.60 91.54 99.33 99.96 Comparison plan 1 35.20 67.69 99.31 99.94 Comparison plan 2 38.36 73.77 98.87 99.50 Comparison plan 3 41.60 80.00 98.77 99.40

[0083] This embodiment discloses a polyester reverse osmosis membrane, which is cleaned by the above method. Figure 1-Figure 8 As shown, it includes a tube shell 1 and a reverse osmosis membrane assembly 5. The reverse osmosis membrane assembly 5 is installed in the tube shell 1. A water inlet chamber 103 is formed at the lower side of the reverse osmosis membrane assembly 5, and a concentrated water chamber 104 is formed at the upper side.

[0084] The tube shell 1 is arranged in an up-down vertical direction, with an end cap 101 installed at the lower end of the tube shell 1 and an end cap 2 102 installed at the upper end. A water inlet cavity 103 is formed between the reverse osmosis membrane assembly 5 and the end cap 101, and a concentrated water cavity 104 is formed between the reverse osmosis membrane assembly 5 and the end cap 2 102. The water inlet pipe 2 is connected to the end cap 101, and the inner cavity of the water production pipe 3 serves as the water production cavity. The water production pipe 3 passes through the end cap 2 102 and is slidably sealed with the end cap 2 102, which can adapt to the up-down lifting and lowering adjustment of the water production pipe 3.

[0085] The reverse osmosis membrane assembly 5 includes a central tube 51 that passes through from top to bottom. The central tube 51 is coaxially fixedly installed in the tube shell 1 . The outer periphery of the central tube 51 is connected and fixed to the inner periphery of the tube shell 1 by an end plate 52 to support the central tube 51 .

[0086] A reverse osmosis membrane material 54 is wound and coated between the outer periphery of the central tube 51 and the inner cavity wall of the tube shell 1. The central tube 51 is provided with a plurality of through holes 511 penetrating the inner and outer peripheries, and the through holes 511 are covered by the reverse osmosis membrane material 54. The water production pipe 3 is passed through the central tube 51, and the water production pipe 3 is provided with a plurality of through holes 31 penetrating the inner and outer axes, and the through holes 31 correspond to the through holes 511 one by one.

[0087] The outer periphery of the water production pipe 3 is slidably sealedly connected to the inner periphery of the central pipe 51 . Specifically, a plurality of sliding sealing rings may be installed on the inner periphery of the central pipe 51 , thereby forming a stable sliding sealing structure.

[0088] The water production pipe 3 has a highest position and a lowest position. At the highest position, the second through hole 31 and the first through hole 511 are mutually dislocated and disconnected. At the lowest position, the second through hole 31 and the first through hole 511 are mutually aligned and connected. By adjusting the water production pipe 3 up and down, the on-off switching between the water production pipe 3 and the central pipe 51 can be realized.

[0089] Reference Figure 2-Figure 4As shown, an adjusting rod 6 is coaxially passed through the water production pipe 3, a piston member 9 is fixedly installed on the outer periphery of the adjusting rod 6, and the outer periphery of the piston member 9 is connected to the inner periphery of the water production pipe 3. The piston member 9 is provided with a plurality of flow guide holes 91 which pass through from top to bottom, and a one-way flow limiting member 92 is installed on the piston member 9, and the one-way flow limiting member 92 uses the flow guide holes 91 to realize upward one-way conduction.

[0090] When the piston 9 moves downward, or during normal water treatment, the one-way flow limiting member 92 can open the guide hole 91; when the piston 9 moves upward, the one-way flow limiting member 92 of the piston 9 can close the guide hole 91, thereby enabling the piston 9 to push the water in the water production pipe 3 upward.

[0091] Reference Figure 6 As shown, the one-way flow limiting member 92 is an elastic rubber sheet and is arranged on the upper side of the piston member 9. The elastic rubber sheet can produce elastic bending deformation and has an annular structure. The inner peripheral portion 921 of the one-way flow limiting member 92 is connected to the piston member 9, and the outer peripheral portion 922 of the one-way flow limiting member 92 is used to seal and cover the flow guide hole 91. The outer peripheral portion 922 of the one-way flow limiting member 92 can be elastically bent upward to open the flow guide hole 91. Under normal circumstances, the flow guide hole 91 can be closed in one direction.

[0092] The outer retaining ring 1 33 and the outer retaining ring 2 38 are fixedly connected to the outer periphery of the water production pipe 3, and the outer retaining ring 1 33 and the outer retaining ring 2 38 protrude outward from the outer periphery of the water production pipe 3 to form upper and lower blocking restrictions. The outer retaining ring 1 33 is located on the upper side of the reverse osmosis membrane assembly 5, and the outer retaining ring 2 38 is located on the lower side of the reverse osmosis membrane assembly 5. The lifting stroke limit is achieved by the outer retaining ring 1 33 and the outer retaining ring 2 38, so that the water production pipe 3 can be adjusted to the highest position and the lowest position, and the limit is achieved by the mortgage blocking.

[0093] Reference Figure 4 As shown, a reflux hole 34 is provided on the outer periphery of the water production pipe 3, corresponding to the lower side of the outer retaining ring 1 33. At the lowest position of the water production pipe 3, the reflux hole 34 is retracted into the central pipe 51 and is sealed and covered, and the outer retaining ring 1 33 is sealed against the upper side of the reverse osmosis membrane assembly 5. At the same time, the through hole 2 31 is opposite to the through hole 1 511, so that the two can be connected to each other and can achieve osmotic flow. Figure 4 As shown, the water production pipe 3 is at the highest point, and the reflux hole 34 will leave the central pipe 51 and be in an open state, so that the water production chamber inside the water production pipe 3 can be connected to the concentrated water chamber 104 through the reflux hole 34.

[0094] Reference Figure 4 , Figure 5As shown, the lower end of the water production pipe 3 is formed with a lower port 35, and the inner circumference of the lower port 35 is fixedly connected with an inner retaining ring 36. The lower end of the adjustment rod 6 is installed with a plug 8, and the water production pipe 3 is at the lowest position, and the plug 8 abuts against the inner retaining ring 36 to seal the lower port 35.

[0095] Specific reference Figure 5 As shown, the upper side of the inner retaining ring 36 forms an inverted cone-shaped conical surface 1 37, and the lower side of the plug 8 forms a matching conical surface 2 81, and the conical surface 2 81 can achieve a pressing seal with the conical surface 1 37. When the adjusting rod 6 and the plug 8 move downward, the conical surface 2 81 on the lower side of the plug 8 presses against the conical surface 1 37 of the inner retaining ring 36, forming a pressing limit and achieving axial centering.

[0096] A connecting hole 82 is provided in the middle of the upper side of the plug 8, and the lower end of the adjusting rod 6 is slidably connected to the connecting hole 82, and can slide up and down relatively. The bottom surface of the connecting hole 82 and the lower end surface of the adjusting rod 6 are elastically connected by a spring 2 83, which can form a downward elastic pressure on the plug 8. When the adjusting rod 6 and the plug 8 move downward, the plug 8 and the inner retaining ring 36 can be abutted against each other up and down, and the adjusting rod 6 and the plug 8 can slide axially up and down, and elastic buffering can be achieved by the spring 2 83. Through the buffering of the spring 2 83, it can be ensured that the outer retaining ring 1 33 on the outer periphery of the water production pipe 3 can be abutted against the upper side of the reverse osmosis membrane assembly 5, and the plug 8 and the inner retaining ring 36 can also be abutted against each other up and down.

[0097] Reference Figure 4 As shown, a support frame 32 is fixedly connected to the inner periphery of the water production pipe 3, and the support frame 32 is provided with a hole that passes through from top to bottom. The support frame 32 is located above the corresponding piston member 9, and a spring 7 is installed between the support frame 32 and the piston member 9. The spring 7 is sleeved outside the adjustment rod 6, and the upper end of the spring 7 can be against the support frame 32, and the lower end of the spring 7 is against the inner periphery of the one-way flow limiting member 9 on the upper side of the piston member 9, and then the spring 7 can apply a downward elastic force to the piston member 9. The linkage between the water production pipe 3 and the adjustment rod 6 can be achieved through the spring 7, the piston member 9 and the support frame 32.

[0098] Further, refer to Figure 8 As shown, in order to facilitate the connection of the pipeline to the upper end of the water production pipe 3, a connecting joint 200 can be installed on the upper end of the water production pipe 3. The adjusting rod 6 passes through the connecting joint 200, and is connected at the connection point by a sliding seal to form a slidable sealed connection. The adjusting rod 6 can smoothly move relative to the connecting joint 200 to achieve lifting and lowering adjustment. In addition, a water production interface 201 is provided on the periphery of the connecting joint 200, and the water production pipeline can be conveniently connected through the water production interface 201.

[0099] Further, refer to Figure 2-Figure 4As shown, the reverse osmosis membrane assembly 5 is divided into several sections, including several splicing sections 50, each of which is installed up and down. The splicing section 50 includes a central tube 51, the length of which is consistent with the length of the splicing section 50, and the central tube 51 is sleeved outside the water production pipe 3.

[0100] Two end plates 52 are fixedly installed on the periphery of the central tube 51, and the periphery of the end plates 52 is fixedly connected to the tube shell 1, and a plurality of water holes 53 are opened on the end plates 52, which are connected vertically, and each water hole 53 can supply water. A separation chamber 105 is formed between two adjacent splicing sections 50, and the separation chamber 105 can separate each splicing section 50. During the flow of water, the concentrated water will pass through the splicing section 50 and the separation chamber 105, so that the water flow can be converted. During the flow, the surface of the reverse osmosis membrane material 54 can be impact-cleaned, and the membrane material can be efficiently cleaned during the cleaning process.

[0101] During the water treatment process of the polyester reverse osmosis membrane, the adjusting rod 6 is driven downward by the driver, so that the plug 8 at the lower end of the adjusting rod 6 is opposite to the inner retaining ring 36, pressing and closing the lower port 35 of the water production pipe 3, and the water production pipe 3 will move to the lowest position; at the same time, the outer retaining ring 1 33 on the upper side of the water production pipe 3 can be pressed against the upper side of the reverse osmosis membrane assembly 5, and the reflux hole 34 is retracted into the central tube 51, so that the outer retaining ring 1 33 and the end plate 52 can be pressed and sealed. When the water production pipe 3 is at the lowest position, the through hole 1 511 and the through hole 2 31 will be relatively connected.

[0102] The treated wastewater flows upward from the concentrated water chamber 104, passes through the reverse osmosis membrane material 54 of the reverse osmosis membrane assembly 5, wherein pure water can flow from the reverse osmosis membrane material 54 along the through hole 1 511 and the through hole 2 31 toward the inner circumference of the water production pipe 3, enter the water production chamber in the water production pipe 3, and then flow out from the upper end along the water production pipe 3. Concentrated water can enter the concentrated water chamber 104 and be discharged from the concentrated water pipe 4.

[0103] During the cleaning process of the polyester reverse osmosis membrane, the cleaning reagent is introduced from the water inlet pipe 2 and discharged from the concentrated water pipe 4 , so as to clean the reverse osmosis membrane material 54 .

[0104] In step b and step d, the cleaning reagent is allowed to stand still in the tube shell 1. The water inlet pipe 2, the concentrated water pipe 4 and the water production interface 201 are cut off and closed, so that the cleaning reagent can stand still in the tube shell 1. During the standing still process, the cleaning reagent can be circulated and refluxed in the tube shell 1 by reciprocating the adjustment rod 6 up and down, so that the cleaning reagent can flow from top to bottom in the reverse osmosis membrane material 54, which is opposite to the direction of the previous normal flushing, and can form reverse cleaning, thereby washing away impurities attached to the surface of the reverse osmosis membrane material 54, and also allowing the cleaning reagent to impact and contact the corners of the reverse osmosis membrane material 54 that are not easy to be cleaned, thereby improving the cleaning effect of the membrane material.

[0105] Reference Figure 7 As shown, the adjusting rod 6 first moves upward from bottom to top, and the adjusting rod 6 and the water production pipe 3 move upward at the same time, and the upward force is transmitted by the spring 1 7, so that the water production pipe 3 can be adjusted to the highest position, and the through hole 1 511 and the through hole 2 31 are mutually dislocated and disconnected; the lower port 35 of the water production pipe 3 and the upper reflux hole 34 will be opened at the same time. Then, the adjusting rod 6 continues to adjust upward, the spring 1 7 will continue to be compressed, and the piston 9 can push the water upward in the water production pipe 3, so that the water flow can flow from the reflux hole 34 on the water production pipe 3 into the concentrated water chamber 104, and the cleaning reagent in the concentrated water chamber 104 will form a top-to-bottom flow at the reverse osmosis membrane material 54, so that the surface of the reverse osmosis membrane material 54 can be reversely flushed, and then the cleaning reagent enters the water inlet chamber 103 on the lower side of the tube shell 1, and then the cleaning reagent in the water inlet chamber 103 enters the water production pipe 3 from the lower port 35 to realize the circulation of the cleaning reagent.

[0106] Then, the adjusting rod 6 moves downward, driving the piston 9 to move downward, and the outer peripheral portion 922 of the one-way flow limiting member 92 is elastically bent upward, which can open the flow guide hole 91, thereby enabling the one-way conduction of the piston 9, until the adjusting rod 6, the piston 9 and the water production pipe 3 are adjusted to the initial state. Then, the adjusting rod 6 moves upward again, and the cleaning agent can be circulated and pumped in the water production pipe 3 through the reciprocating movement of the adjusting rod 6.

[0107] The cleaning scheme of Example 1 is different in that during the standing process of step b and step d, the cleaning liquid is circulated and reversed in the reverse osmosis membrane assembly 5.

[0108] By circulating and pumping the cleaning reagent in the tube shell 1, the cleaning reagent can be pushed back to the reverse osmosis membrane assembly 5, so that the cleaning reagent can backwash the reverse osmosis membrane assembly 5. Backwashing is combined with the previous normal flushing method, so that more flushing conditions are applied to the reverse osmosis membrane material 54, which can effectively flush and clean the membrane material surface, and further improve the flux and flux recovery rate after cleaning.

[0109] In addition, during the backwashing process on the surface of the reverse osmosis membrane material 54, the water is circulated in the shell 1, so that the water can flow between the inner and outer peripheries of the water production pipe 3, and the reverse osmosis membrane material 54 can be backwashed during the circulation process. During the backwashing process, the pressure difference on both sides of the reverse osmosis membrane material 54 can be avoided to be too large, so that the pressure balance on both sides of the reverse osmosis membrane material 54 can be maintained, and the effect of the backwashing process can be improved.

[0110] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for cleaning organic pollution of polyester reverse osmosis membrane, characterized in that: The following steps are involved: (a) flushing the reverse osmosis membrane with pure water; (b) using sodium bicarbonate and fatty alcohol polyoxyethylene ether to form a mixed cleaning solution, and using the mixed cleaning solution to clean the reverse osmosis membrane after cleaning in step (a); (c) flushing the reverse osmosis membrane after cleaning in step (b) with pure water until it becomes neutral; (d) cleaning the reverse osmosis membrane after cleaning in step (c) with a disodium ethylenediaminetetraacetic acid solution; (e) flushing the reverse osmosis membrane after cleaning in step (d) with pure water until it becomes neutral; (f) cleaning the reverse osmosis membrane after cleaning in step (e) with a malic acid solution; (g) Rinse the reverse osmosis membrane cleaned in step (f) with pure water until it becomes neutral.

2. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (a), pure water is flushed at a flow rate of 80 to 120 L / h for 10 to 20 minutes.

3. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (b), the mixed cleaning solution is formed by mixing 0.03-0.07 wt % of sodium bicarbonate and 0.04-0.08 wt % of fatty alcohol polyoxyethylene ether.

4. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (b), the mixed cleaning solution is first cleaned at a flow rate of 100-150 L / h for 15-25 min, and then cleaned at a flow rate of 200-250 L / h for 15-25 min, and then the cleaning solution is placed in the reverse osmosis membrane and maintained at rest for at least 10 min.

5. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (d), the concentration of the disodium edetate solution is 0.02wt% to 0.06wt%.

6. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (d), the disodium ethylenediaminetetraacetic acid solution is first cleaned at a flow rate of 120 to 200 L / h for 20 to 30 minutes, and then the cleaning solution is placed in the reverse osmosis membrane for at least 10 minutes.

7. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (f), the concentration of the malic acid solution is 0.8 wt % to 1.2 wt %.

8. The method for cleaning organic pollution of polyester reverse osmosis membrane according to claim 1, characterized in that: In step (f), the malic acid solution is cleaned at a flow rate of 100 to 150 L / h for 15 to 25 min.

9. A polyester reverse osmosis membrane, characterized in that: The contaminated reverse osmosis membrane is cleaned by the method for cleaning organic pollution of a polyester reverse osmosis membrane as described in any one of claims 1 to 8.

10. A polyester reverse osmosis membrane, characterized in that: It comprises a tube shell (1) and a reverse osmosis membrane assembly (5), wherein the reverse osmosis membrane assembly (5) is installed in the tube shell (1), a water inlet chamber (103) is formed on the lower side of the reverse osmosis membrane assembly (5), and a concentrated water chamber (104) is formed on the upper side; The reverse osmosis membrane assembly (5) comprises a central tube (51) which passes through from top to bottom, the central tube (51) being coaxially fixedly installed in the tube shell (1), and a reverse osmosis membrane material (54) being wound and coated between the outer periphery of the central tube (51) and the inner cavity wall of the tube shell (1); the central tube (51) is provided with a plurality of through holes (511) which pass through the inner and outer peripheries, and the through holes (511) are covered by the reverse osmosis membrane material (54); The water production pipe (3) is inserted into the central pipe (51), and the water production pipe (3) is provided with a plurality of through holes (31) penetrating the inner and outer axes, and the through holes (31) correspond to the through holes (511) one by one; An adjusting rod (6) is coaxially passed through the water production pipe (3); a piston member (9) is fixedly mounted on the outer periphery of the adjusting rod (6); the outer periphery of the piston member (9) is piston-connected to the inner periphery of the water production pipe (3); the piston member (9) is provided with a plurality of flow guide holes (91) extending vertically; the piston member (9) is provided with a one-way flow limiting member (92); the one-way flow limiting member (92) realizes one-way conduction upwards by means of the corresponding flow guide holes (91).

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