A method for cleaning organic contamination of a polyester reverse osmosis membrane

Abstract

The application discloses a kind of polyester reverse osmosis membrane organic pollution cleaning method, comprising the following steps: (a) with pure water to reverse osmosis membrane is flushed;(b) using sodium bicarbonate and fatty alcohol polyoxyethylene ether mixed to form mixed cleaning solution, with mixed cleaning solution to the reverse osmosis membrane cleaned in step (a) is cleaned;(c) with pure water flushing to the reverse osmosis membrane cleaned in step (b) is flushed, flushes to neutral;(d) with ethylenediaminetetraacetic acid disodium solution to the reverse osmosis membrane cleaned in step (c) is cleaned;(e) with pure water flushing to the reverse osmosis membrane cleaned in step (d) is flushed, flushes to neutral;(f) with malic acid solution to the reverse osmosis membrane cleaned in step (e) is cleaned;(g) with pure water flushing to the reverse osmosis membrane cleaned in step (f) is flushed, flushes to neutral.The application can efficiently, stably, comprehensively, gently clean pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to water treatment equipment, more particularly, to a polyester reverse osmosis membrane, and to a polyester reverse osmosis membrane organic contamination cleaning method. BACKGROUND

[0002] In the wide application of modern membrane separation technology, polyester reverse osmosis membranes have been widely used in many fields due to their unique chemical stability, good mechanical strength and suitable hydrophilicity, and play a key role in the treatment of industrial wastewater with high salinity and complex organic pollutants and in specific chemical separation processes. However, they inevitably face the severe challenge of organic contamination during operation.

[0003] Although the good hydrophilicity of polyester reverse osmosis membranes makes them more resistant to contamination than other reverse osmosis membranes, contaminants such as bovine serum albumin, oil and fat substances, and various polysaccharides are still easy to adsorb and deposit on the surface of polyester reverse osmosis membranes. Related studies have shown that in some chemical wastewater treatment scenarios, the flux of polyester reverse osmosis membranes can be reduced by 40% to 60% after a period of operation, which seriously affects the separation efficiency and service life of the membranes.

[0004] 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 results or damage to the membrane structure. Some strong alkaline or strong oxidizing cleaning agents can cause the breakage or hydrolysis of polyester molecular chains, reducing the mechanical properties and chemical stability of the membranes.

[0005] Therefore, a new solution is needed to solve the problem of cleaning organic contamination of polyester reverse osmosis membranes. SUMMARY

[0006] The present application aims to overcome the shortcomings of the prior art and provide a polyester reverse osmosis membrane organic contamination cleaning method and a polyester reverse osmosis membrane.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A polyester reverse osmosis membrane organic contamination cleaning method, comprising the following steps:

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

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

[0011] (c) rinsing the reverse osmosis membrane cleaned in step (b) with pure water until it is neutral.

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

[0013] (e) rinsing the reverse osmosis membrane after step (d) with pure water until neutral;

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

[0015] (g) rinsing the reverse osmosis membrane after step (f) with pure water until neutral.

[0016] In step (a), the pure water is rinsed at a flow rate of 80-120 L / h for 10-20 min.

[0017] In step (b), the mixed cleaning solution is formed by mixing 0.03wt%-0.07wt% sodium bicarbonate and 0.04wt%-0.08wt% fatty alcohol polyoxyethylene ether.

[0018] In step (b), the mixed cleaning solution 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 solution is left in the reverse osmosis membrane for at least 10 min.

[0019] In step (d), the concentration of the disodium ethylenediaminetetraacetate solution is 0.02wt%-0.06wt%.

[0020] In step (d), the disodium ethylenediaminetetraacetate solution is first cleaned at a flow rate of 120-200 L / h for 20-30 min, and then the cleaning solution is left in the reverse osmosis membrane for at least 10 min.

[0021] In step (f), the concentration of the malic acid solution is 0.8wt%-1.2wt%.

[0022] In step (f), the malic acid solution is cleaned at a flow rate of 100-150 L / h for 15-25 min.

[0023] The application further provides a polyester reverse osmosis membrane, which is cleaned by the polyester reverse osmosis membrane organic contamination cleaning method.

[0024] The application further provides a polyester reverse osmosis membrane, which comprises a tube shell and a reverse osmosis membrane assembly, the reverse osmosis membrane assembly is installed in the tube shell, a water inlet cavity is formed on the lower side of the reverse osmosis membrane assembly, and a concentrated water cavity is formed on the upper side of the reverse osmosis membrane assembly.

[0025] The reverse osmosis membrane assembly comprises a through center tube, which is coaxially fixedly installed in a tube shell, and a reverse osmosis membrane material is wrapped between the outer periphery of the center tube and the inner cavity wall of the tube shell; the center tube is provided with a plurality of through holes one penetrating the inner and outer peripheries, and the through holes one are covered by the reverse osmosis membrane material;

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

[0027] The water production pipe is coaxially arranged with an adjusting rod, the outer periphery of the adjusting rod is fixedly installed with a piston, the outer periphery of the piston is connected with the inner periphery of the water production pipe, the piston is provided with a plurality of through flow holes penetrating upward and downward, the piston is installed with a one-way flow limiting piece, and the one-way flow limiting piece realizes upward one-way conduction to the through flow holes.

[0028] By means of the polyester reverse osmosis membrane, the cleaning liquid in the polyester reverse osmosis membrane can be pushed back to adjust the flow direction of the cleaning liquid in the cleaning process, mainly in the case that the cleaning liquid is static. Through the forward and reverse flow, the surface of the membrane material can be effectively sheared and impacted, the pollutants on the surface of the membrane material in the static process are partially detached and dissolved, and the cleaning effect on the membrane material can be improved. The cleaning liquid can clean the corner position in the membrane material, and the cleaning effect in the static process is further improved.

[0029] In summary, the present application has the following advantages:

[0030] The cleaning method has high flux recovery performance. After cleaning, the flux recovery rate of the polyester reverse osmosis membrane can reach more than 90%. In many 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, effectively prolongs the service life of the membrane, and compared with the traditional cleaning process, the membrane replacement cycle can be prolonged by 2 to 3 times, significantly reducing the membrane replacement cost and operation and maintenance cost, and bringing significant economic benefits to enterprises.

[0031] The cleaning method has better membrane compatibility and stability. Compared with the traditional cleaning method, the cleaning process has high compatibility with the polyester reverse osmosis membrane, and can effectively protect the chemical structure and physical properties of the membrane in the cleaning process. By avoiding the 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 quality conditions is ensured, the system downtime caused by membrane failure is reduced, the production efficiency is improved, and the reliability and stability of enterprise production and operation are enhanced.

[0032] The cleaning method has comprehensive pollutant removal capability. The cleaning method has strong removal capability for various organic pollutants, including proteins, polysaccharides, oils and fats and composite pollutants, can completely remove the organic pollution layer on the membrane surface and in the pore channel, 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 the polyester reverse osmosis membrane technology in the water treatment field, and has important significance for promoting the progress of the industry. BRIEF DESCRIPTION OF DRAWINGS

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

[0034] Figure 2 It is a sectional view of one polyester reverse osmosis membrane in the embodiment;

[0035] Figure 3 It is a sectional view of one polyester reverse osmosis membrane in the embodiment;

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

[0037] Figure 5 It is a 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 and the one-way flow limiting piece in the embodiment;

[0039] Figure 7 It is a schematic diagram of the backflow of the water production pipe and the reverse osmosis membrane assembly in the embodiment.

[0040] Figure 8 It is a schematic diagram of the structure of the connecting joint in the embodiment.

[0041] The drawings show that: the shell 1; the end cap one 101; the end cap two 102; the water inlet cavity 103; the concentrated water cavity 104; the partition cavity 105; the connecting joint 200; the water production interface 201; the water inlet pipe 2; the water production pipe 3; the through hole two 31; the support frame 32; the outer blocking ring one 33; the backflow hole 34; the lower end 35; the inner blocking ring 36; the conical surface one 37; the outer blocking ring two 38; the concentrated water pipe 4; the reverse osmosis membrane assembly 5; the spliced segment 50; the center pipe 51; the through hole one 511; the end plate 52; the water passing hole 53; the reverse osmosis membrane material 54; the adjusting rod 6; the spring one 7; the plug 8; the conical surface two 81; the connecting hole 82; the spring two 83; the piston 9; the flow guide hole 91; the one-way flow limiting piece 92; the inner peripheral part 921; the outer peripheral part 922. DETAILED DESCRIPTION

[0042] With reference to the accompanying drawings: the technical solutions in the embodiments of the present application will be apparently and completely described, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present application.

[0043] The present embodiment discloses a kind of polyester reverse osmosis membrane organic pollution cleaning method, comprising the following steps:

[0044] (a) with pure water to reverse osmosis membrane is washed, with 80 ~ 120L / h flow rate washes 10 ~ 20min;This step utilizes the mechanical shear force of water flow to remove the organic pollutants and part of impurities loosely attached to the membrane surface, while reducing the load of subsequent chemical cleaning, and help to protect the membrane surface from direct impact of subsequent chemical reagent.

[0045] (b) 0.03wt% ~ 0.07wt% sodium bicarbonate and 0.04wt% ~ 0.08wt% fatty alcohol polyoxyethylene ether are mixed to form a mixed cleaning solution, and the reverse osmosis membrane after step (a) is cleaned with the mixed cleaning solution;First, with 100 ~ 150L / h flow rate washes 15 ~ 25min, so that the reagent is fully contacted with the organic pollutants on the membrane surface;Again, with 200 ~ 250L / h flow rate washes 15 ~ 25min, increase the flow to increase its mechanical shear force, so that the loosened but not washed off pollutants are further detached or dissolved in the cleaning solution;Again, the cleaning solution is placed in the reverse osmosis membrane, and the pollutants on the membrane surface and the detached pollutants are fully dissolved for at least 10min, to further achieve the cleaning effect. As a relatively mild alkaline substance, sodium bicarbonate can weakly hydrolyze part of the organic pollutants without seriously affecting the polyester structure, while the fatty alcohol polyoxyethylene ether reduces the adhesion of the pollutants to the membrane surface by using its good surface activity.

[0046] (c) with pure water to flush the reverse osmosis membrane after step (b) is washed, and the membrane surface is washed to neutral, to ensure that the chemical reagent is completely removed, to avoid affecting the effect of the next stage of reagent cleaning.

[0047] (d) with 0.02wt% ~ 0.06wt% ethylenediamine tetraacetic acid disodium solution to clean the reverse osmosis membrane after step (c) is washed;First, with 120 ~ 200L / h flow rate washes 20 ~ 30min, and then the cleaning solution is placed in the reverse osmosis membrane, and maintained for at least 10min;Ethylenediamine tetraacetic acid disodium can effectively complex the metal ions that may be adsorbed on the membrane surface, prevent them from promoting the interaction between the organic pollutants and the membrane surface, and further assist in removing part of the organic pollutants.

[0048] (e) The reverse osmosis membrane after step (d) is washed with pure water to neutralize, ensuring that the chemical reagents remaining on the membrane surface are completely removed, avoiding affecting the effect of the next stage of reagent cleaning.

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

[0050] (g) The reverse osmosis membrane after step (f) is washed with pure water to neutralize, ensuring that the chemical reagents remaining on the membrane surface are completely removed, preventing them from adversely affecting the performance of the membrane and allowing the membrane to be in the best operating state.

[0051] In step (a), the pure water flushing is based on the principle of fluid mechanics, which removes loose contaminants and impurities on the membrane surface by controlling the appropriate water flow rate and flushing time, using the shearing force and scouring effect of water flow, 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 together. Sodium bicarbonate NaHCO3 provides a weak alkaline environment in the solution, and the carbonate and hydroxide ions produced by its hydrolysis can react with certain functional groups in organic pollutants, promoting the decomposition of organic pollutants 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 its hydrophilic and hydrophobic groups in the molecular structure, making it easier for the pollutants to detach from the membrane surface. The two work together to achieve preliminary removal of organic pollutants.

[0053] In step (d), ethylenediaminetetraacetic acid disodium EDTA-2Na complexation, the multiple carboxyl and amino groups in the ethylenediaminetetraacetic acid disodium EDTA-2Na molecule can form stable complexes with metal ions adsorbed on the membrane surface, thereby destroying the promoting effect of metal ions on the interaction between organic pollutants and the membrane surface. At the same time, changes in the local environment during complexation can help further decompose and remove some organic pollutants.

[0054] In step (d), the ethylenediaminetetraacetic acid disodium EDTA-2Na solution cleaning link considers the potential impact of microbial contamination in membrane pollution, and a composite bactericide extracted from natural plants can be added. The composite bactericide is composed of multiple plant active ingredients, such as tea tree essential oil and thyme extract, and has broad-spectrum antibacterial properties. 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 surface of the membrane and in the pores, prevent the growth of microorganisms to form a biofilm, reduce the adsorption and fixation of organic pollutants by microorganisms, thereby indirectly enhancing the removal effect of organic pollutants; on the other hand, the natural ingredients have good compatibility with the polyester reverse osmosis membrane and do not damage the membrane structure like some traditional chemical bactericides, ensuring the chemical stability and mechanical strength of the membrane. The composite bactericide and ethylenediaminetetraacetic acid disodium EDTA-2Na have a synergistic effect. While complexing metal ions, ethylenediaminetetraacetic acid disodium EDTA-2Na changes the microenvironment on the membrane surface, making it easier for the composite bactericide to penetrate the deep structure of the membrane and exert its antibacterial effect. At the same time, after the composite bactericide kills microorganisms, the microbial cell structure is destroyed, and the organic components released are more easily removed by subsequent cleaning agents, further improving the comprehensive removal capacity of the cleaning process for organic pollutants and microbial contamination.

[0056] In step (f), if the membrane is seriously contaminated with inorganic pollutants, the cleaning time can be appropriately increased or the cleaning method of "0.03wt%~0.07wt% sodium bicarbonate NaHCO3 and 0.04wt%~0.08wt% fatty alcohol polyoxyethylene ether AEO mixed solution" can be used to effectively clean the fine details. The acidic environment of malic acid can further hydrolyze or decompose the residual organic pollutants, and the carboxyl groups in the molecule can form complexes with metal ions and inorganic salt crystals, which are removed from the membrane surface under the action of water flow, achieving deep purification and performance recovery of the membrane surface.

[0057] In each step, the cleaning reagent uses different cleaning flow rates and different cleaning times, or uses the cleaning mode of "small flow cleaning + large flow cleaning + standing", which helps to deeply clean the attached pollutants without damaging the polyester layer structure of the membrane sheet.

[0058] In each step, the cleaning liquid can be used in the mode of first external discharge and then recycling. In the current step, the cleaning liquid of the current step is first introduced to flush out all the cleaning liquid of the previous step, which is conducive to the action of the cleaning liquid.

[0059] By selecting NaHCO3, AEO, EDTA-2Na and malic acid and other chemical agents, an efficient cleaning system for organic pollution of the polyester reverse osmosis membrane is formed in a specific concentration range, which can effectively and gently tilt the polyester reverse osmosis membrane, ensure the cleaning effect, and ensure the safety of the membrane structure and prolong the effective service life of the membrane material.

[0060] During the cleaning process, by dynamically adjusting the cleaning liquid in the membrane, and cooperating with static rest, the pollutants can be effectively and thoroughly dissolved in the cleaning liquid, and the cleaning of the membrane is effectively ensured.

[0061] Combined with the chemical structure and physical properties of the polyester reverse osmosis membrane, the above process and cleaning reagent can effectively clean the polyester material, ensure efficient cleaning, and avoid damage to the membrane structure to the greatest extent, and ensure long-term stable operation of the membrane. The cleaning method of the embodiment can also be applied to the wastewater zero discharge process of high-salt printing and dyeing wastewater inorganic salt separation in solution form.

[0062] Specifically, the polyester reverse osmosis membrane after pollution is cleaned by using the cleaning method in the embodiment and the methods of the other three comparative examples, respectively.

[0063] The polyester reverse osmosis membrane used has an original pure water flux of 52 LMH, and a polyester reverse osmosis membrane rejection rate of 99.37% under standard conditions with 2000 mg / L NaCl as the test liquid. After a period of industrial wastewater (which can be simulated industrial wastewater, composed of bovine serum albumin, oil and fat substances, various polysaccharides and various inorganic salts, etc.) operation, the flux decreases to 35 LMH, and the rejection rate is 99.21%.

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

[0065] Embodiment 1

[0066] The cleaning steps of the embodiment are:

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

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

[0069] (c) rinsing the reverse osmosis membrane after step (b) with pure water to neutralize;

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

[0071] (e) rinsing the reverse osmosis membrane after step (d) with pure water until neutral;

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

[0073] (g) rinsing the reverse osmosis membrane after step (f) with pure water until neutral, so that the reverse osmosis membrane can be cleaned and be in an optimal operating state.

[0074] Comparative Example 1

[0075] The cleaning steps of Comparative Example 1 are as follows: first, the contaminated membrane is preliminarily rinsed with pure water at a flow rate of 120 L / h for 15 min; then, 1.5 wt% citric acid is used to clean for 25 min at a flow rate of 220 L / h; finally, the membrane is rinsed with pure water until neutral, so that the membrane is in an optimal operating state.

[0076] Comparative Example 2

[0077] The cleaning steps of Comparative Example 2 are as follows: first, the contaminated membrane is preliminarily rinsed with pure water at a flow rate of 120 L / h for 15 min; then, 0.1 wt% sodium hydroxide + 0.025 wt% sodium dodecyl benzene sulfonate is used to clean for 25 min; finally, the membrane is rinsed with pure water until neutral, so that the membrane is in an optimal operating state.

[0078] Comparative Example 3

[0079] The cleaning steps of Comparative Example 3 are as follows: first, the contaminated membrane is preliminarily rinsed with pure water at a flow rate of 120 L / h for 15 min; then, 0.1 wt% sodium hydroxide + 0.025 wt% sodium dodecyl benzene sulfonate mixed solution is used to clean, first cleaning for 25 min at a flow rate of 120 L / h to allow the reagent to fully contact the contaminants, then cleaning for 25 min at a flow rate of 220 L / h to increase the mechanical shear force, followed by standing for more than 10 min to fully dissolve the contaminants; then, the membrane is rinsed with pure water until neutral to ensure that the residual reagent is removed; then, 2.0 wt% hydrochloric acid solution is used to clean for 25 min at a flow rate of 120 L / h; finally, the membrane is rinsed with pure water until neutral, so that the membrane is in an optimal operating state.

[0080] The cleaning effects of the four methods on the polyester reverse osmosis membrane are shown in Table 1. The scheme has excellent cleaning effect on the contaminated polyester reverse osmosis membrane, and realizes good recovery of membrane flux and interception performance without damaging the structure of the membrane itself.

[0081] Table 1 Change of membrane interception rate after cleaning by different cleaning schemes

[0082] Scheme Flux after cleaning / LMH Flux recovery / % Retention after cleaning / % Retention recovery / % Inventive scheme 47.60 91.54 99.33 99.96 Comparative scheme 1 35.20 67.69 99.31 99.94 Comparative scheme 2 38.36 73.77 98.87 99.50 Comparative scheme 3 41.60 80.00 98.77 99.40

[0083] The embodiment discloses a polyester reverse osmosis membrane, which is suitable for cleaning by the method described above, and refers to Figures 1-8 As shown in the figure, it comprises 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 cavity 103 is formed on the lower side of the reverse osmosis membrane assembly 5, and a concentrated water cavity 104 is formed on the upper side of the reverse osmosis membrane assembly 5.

[0084] The tube shell 1 is arranged in the vertical direction from top to bottom, an end cover one 101 is installed at the lower end of the tube shell 1, and an end cover two 102 is installed at the upper end of the tube shell 1. The water inlet cavity 103 is formed between the reverse osmosis membrane assembly 5 and the end cover one 101, and the concentrated water cavity 104 is formed between the reverse osmosis membrane assembly 5 and the end cover two 102. The water inlet pipe 2 is connected to the end cover one 101, and the inner cavity of the water production pipe 3 serves as a water production cavity. The water production pipe 3 penetrates through the end cover two 102 and is slidably and sealingly connected to the end cover two 102, so as to adapt to the up-down adjustment of the water production pipe 3.

[0085] The reverse osmosis membrane assembly 5 comprises a center pipe 51 penetrating from top to bottom, which is coaxially and fixedly installed in the tube shell 1 and is connected and fixed between the outer periphery of the center pipe 51 and the inner periphery of the tube shell 1 through an end plate 52, so as to support the center pipe 51.

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

[0087] The outer periphery of the water production pipe 3 is slidably and sealingly connected to the inner periphery of the center pipe 51, and specifically a plurality of sliding sealing rings can be installed on the inner periphery of the center pipe 51, so as to form a stable sliding sealing structure.

[0088] The water production pipe 3 has a highest position and a lowest position, at the highest position, the through holes two 31 and the through holes one 511 are mutually misaligned and disconnected, and at the lowest position, the through holes two 31 and the through holes one 511 are mutually aligned and communicated. By adjusting the water production pipe 3 up and down, the on-off switching between the water production pipe 3 and the center pipe 51 can be realized.

[0089] Referring to Figures 2-4As shown, the adjusting rod 6 is coaxially arranged in the water production pipe 3, and the piston member 9 is fixedly arranged on the outer periphery of the adjusting rod 6. The outer periphery of the piston member 9 is in piston connection with the inner periphery of the water production pipe 3. The piston member 9 is provided with a plurality of up-and-down through flow guide holes 91, and is provided with a one-way flow limiting member 92.

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

[0091] Referring to 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 be elastically bent and deformed, and has a ring structure. The inner periphery 921 of the one-way flow limiting member 92 is connected to the piston member 9, and the outer periphery 922 of the one-way flow limiting member 92 is used to seal and cover the flow guide holes 91. The outer periphery 922 of the one-way flow limiting member 92 can be elastically bent upward to open the flow guide holes 91, and under normal circumstances, the flow guide holes 91 can be one-way closed.

[0092] The outer periphery of the water production pipe 3 is fixedly connected to the outer blocking ring one 33 and the outer blocking ring two 38. The outer blocking ring one 33 and the outer blocking ring two 38 protrude outward from the outer periphery of the water production pipe 3, forming two upper and lower blocking restrictions. The outer blocking ring one 33 is located on the upper side of the reverse osmosis membrane assembly 5, and the outer blocking ring two 38 is located on the lower side of the reverse osmosis membrane assembly 5. The outer blocking ring one 33 and the outer blocking ring two 38 realize lifting stroke limiting, so that the water production pipe 3 can be adjusted to the highest position and the lowest position, and limiting is realized by blocking.

[0093] Referring to Figure 4 As shown, the reflux hole 34 is arranged on the outer periphery of the water production pipe 3, corresponding to the lower side of the outer blocking ring one 33. When the water production pipe 3 is at the lowest position, the reflux hole 34 is sealed and covered in the central pipe 51, and the outer blocking ring one 33 is sealed and abuts against the upper side of the reverse osmosis membrane assembly 5. At the same time, the through hole two 31 and the through hole one 511 are opposite to each other, so that they can communicate with each other and realize permeation. Figure 4 As shown, when the water production pipe 3 is at the highest position, the reflux hole 34 will be away from the central pipe 51 and can be in an open state, so that the water production cavity inside the water production pipe 3 can be connected to the concentrated water cavity 104 through the reflux hole 34.

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

[0095] With reference to the specific embodiments Figure 5 As shown, the upper side of the inner blocking ring 36 is formed with a tapered surface one 37 in the shape of an inverted cone, and the lower side of the plug 8 is formed with a tapered surface two 81 which is adapted to the tapered surface one 37 and can abut against the tapered surface one 37 to form a sealing abutment. When the adjusting rod 6 and the plug 8 move downward, the tapered surface two 81 of the lower side of the plug 8 abuts against the tapered surface one 37 of the inner blocking ring 36, which can form an abutment limit and realize axial centering.

[0096] A connecting hole 82 is formed in the upper side of the plug 8, and the lower end of the adjusting rod 6 is slidingly connected in the connecting hole 82 and can be adjusted by sliding up and down. The bottom surface of the connecting hole 82 and the lower end surface of the adjusting rod 6 are elastically connected by a spring two 83, which can form an elastic pressure downward on the plug 8. When the adjusting rod 6 and the plug 8 move downward, the plug 8 can abut against the inner blocking ring 36 up and down, and the adjusting rod 6 and the plug 8 can slide up and down in the axial direction and be elastically buffered by the spring two 83. Through the buffering of the spring two 83, it can be ensured that the outer blocking ring one 33 of the outer periphery of the water production pipe 3 can abut against the upper side of the reverse osmosis membrane assembly 5, and at the same time, the plug 8 and the inner blocking ring 36 can also abut against each other up and down.

[0097] With reference to the specific embodiments 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 formed with a hole which penetrates up and down. The support frame 32 is located above the corresponding piston 9, and a spring one 7 is installed between the support frame 32 and the piston 9, the spring one 7 is sleeved on the adjusting rod 6, the upper end of the spring one 7 can abut against the support frame 32, and the lower end of the spring one 7 abuts against the inner periphery of the upper side of the one-way flow limiting piece 9 of the piston 9, so that the spring one 7 can exert a downward elastic force on the piston 9. Through the spring one 7, the piston 9 and the support frame 32, the water production pipe 3 and the adjusting rod 6 can be linked.

[0098] Further, with reference to the specific embodiments Figure 8 As shown, in order to facilitate the connection of the pipe to the upper end of the water production pipe 3, a connecting joint 200 can be installed at the upper end of the water production pipe 3. The adjusting rod 6 penetrates through the connecting joint 200 and is connected by a sliding sealing piece at the connection and forms a sealable and slidable connection. The adjusting rod 6 can smoothly slide up and down relative to the connecting joint 200 to realize the lifting adjustment. In addition, a water outlet 201 is arranged on the outer periphery of the connecting joint 200, and the water outlet 201 can be conveniently connected to the water production pipeline.

[0099] Further, with reference to the specific embodiments Figures 2-4As shown, the reverse osmosis membrane assembly 5 is divided into several segments, including several spliced segments 50, each spliced segment 50 being arranged in an up-down installation manner. The spliced segment 50 includes a center pipe 51, the length of the center pipe 51 being consistent with the length of the spliced segment 50, and the center pipe 51 being sleeved outside the water production pipe 3.

[0100] Two end plates 52 are fixedly installed outside the center pipe 51, the outer periphery of the end plate 52 being fixedly connected with the pipe shell 1, and a plurality of water passing holes 53 are formed in the end plate 52 and penetrate the end plate 52 in an up-down direction, each water passing hole 53 being capable of allowing water flow. Between the adjacent two spliced segments 50, a separation cavity 105 is formed, which can separate the spliced segments 50. In the water flow process, the concentrated water will pass through the spliced segment 50 and the separation cavity 105, so that the water flow can be converted, and in the water flow process, the surface of the reverse osmosis membrane material 54 can be impacted and cleaned, and the membrane material can be efficiently cleaned in the cleaning process.

[0101] In 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 stop ring 36, and the lower port 35 of the water production pipe 3 is pressed and closed, and the water production pipe 3 will move to the lowest position; at the same time, the outer stop ring I 33 on the upper side of the water production pipe 3 can be opposite to the upper side of the reverse osmosis membrane assembly 5, the reflux hole 34 is retracted into the center pipe 51, so that the outer stop ring I 33 and the end plate 52 are pressed and sealed. The water production pipe 3 is at the lowest position, the through hole I 511 and the through hole II 31 are connected.

[0102] The water flow of the treated wastewater flows upward from the concentrated water cavity 104, passes through the reverse osmosis membrane material 54 of the reverse osmosis membrane assembly 5, and the pure water can flow from the reverse osmosis membrane material 54 to the inner periphery of the water production pipe 3 along the through hole I 511 and the through hole II 31, and then enters the water production cavity in the water production pipe 3 and then flows out from the upper end of the water production pipe 3. The concentrated water can enter the concentrated water cavity 104 and be discharged from the concentrated water pipe 4.

[0103] In 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 agent is static in the pipe shell 1. The water inlet pipe 2, the concentrated water pipe 4 and the water outlet interface 201 are cut off and closed, so that the cleaning agent can be static in the pipe shell 1. During the static process, the cleaning agent can be circulated and returned in the pipe shell 1 by the up-down reciprocating adjusting rod 6, so that the cleaning agent can form a top-down flow in the reverse osmosis membrane material 54, which can be opposite to the previous normal flushing direction, can form a reverse cleaning, and can flush the impurities attached to the surface of the reverse osmosis membrane material 54, so that the cleaning agent can impact the corners of the reverse osmosis membrane material 54 which are not easy to be cleaned, and the cleaning effect of the membrane material can be improved.

[0105] Referring to Figure 7 As shown, the adjusting rod 6 first moves from bottom to top, and the adjusting rod 6 and the water outlet pipe 3 move upward at the same time. The upward force is transmitted by the spring 7, so that the water outlet pipe 3 can be adjusted to the highest position, and the through hole 511 and the through hole 31 are disconnected. The lower end port 35 of the water outlet pipe 3 and the upper return flow hole 34 are opened at the same time. Then, the adjusting rod 6 continues to adjust upward, the spring 7 is continuously compressed, and the piston 9 can push the water upward in the water outlet pipe 3, so that the water flow can flow from the return flow hole 34 of the water outlet pipe 3 into the concentrated water cavity 104. The cleaning agent in the concentrated water cavity 104 can form a top-down flow in the reverse osmosis membrane material 54, so that the surface of the reverse osmosis membrane material 54 can be reverse washed. Then, the cleaning agent enters the water inlet cavity 103 at the lower side of the pipe shell 1. Then, the cleaning agent in the water inlet cavity 103 enters the water outlet pipe 3 from the lower end port 35 to realize the circulation of the cleaning agent.

[0106] Then, the adjusting rod 6 moves downward, which drives the piston 9 to move downward. 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, so that the piston 9 can be one-way conducted. Until the adjusting rod 6, the piston 9 and the water outlet pipe 3 are adjusted to the initial state. Then, the adjusting rod 6 moves from bottom to top again, and the adjusting rod 6 is adjusted by up-down reciprocating motion, so that the cleaning agent in the water outlet pipe 3 can be circulated and pumped.

[0107] According to the cleaning scheme of example 1, the difference is that the cleaning liquid is circulated and returned in the reverse osmosis membrane assembly 5 during the static process of step b and step d.

[0108] By circulating and pumping the cleaning agent in the pipe shell 1, the cleaning agent can be pushed to the reverse osmosis membrane assembly 5, so that the cleaning agent can be returned and washed. The return and washing is combined with the previous normal washing mode, so that more washing state can be applied to the reverse osmosis membrane material 54, which can effectively realize the surface washing and cleaning of the membrane material, and further improve the flux and flux recovery rate after cleaning.

[0109] In addition, in the backwash process of the reverse osmosis membrane material 54, the circulation in the shell 1 is adopted to form the flow between the inner and outer periphery of the water production pipe 3, and the reverse osmosis membrane material 54 can be cleaned in the flow process. In the backwash process, the pressure difference between the two sides of the reverse osmosis membrane material 54 can be avoided, and the pressure balance on both sides of the reverse osmosis membrane material 54 can be maintained, and the effect of the backwash process can be improved.

[0110] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as the protection scope of the present application.

Claims

1. A method for cleaning a polyester reverse osmosis membrane from organic contamination, characterized in that, The method comprises the following steps: (a) rinsing the reverse osmosis membrane with pure water; (b) cleaning the reverse osmosis membrane cleaned in step (a) with a mixed cleaning solution formed by mixing sodium bicarbonate and fatty alcohol polyoxyethylene ether; in step (b), the mixed cleaning solution is formed by mixing 0.03-0.07 wt% sodium bicarbonate and 0.04-0.08 wt% fatty alcohol polyoxyethylene ether, the mixed cleaning solution 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 after cleaning, the cleaning solution is left in the reverse osmosis membrane for at least 10 min; (c) rinsing the reverse osmosis membrane cleaned in step (b) with pure water until neutral; (d) cleaning the reverse osmosis membrane cleaned in step (c) with a disodium ethylenediaminetetraacetate solution; in step (d), the disodium ethylenediaminetetraacetate solution has a concentration of 0.02 wt%-0.06 wt%, the disodium ethylenediaminetetraacetate solution is first cleaned at a flow rate of 120-200 L / h for 20-30 min, and after cleaning, the cleaning solution is left in the reverse osmosis membrane for at least 10 min; The disodium ethylenediaminetetraacetate solution contains a composite bactericide, and the composite bactericide is formed by mixing one or both of tea tree oil and thyme extract; (e) rinsing the reverse osmosis membrane cleaned in step (d) with pure water until neutral; (f) cleaning the reverse osmosis membrane cleaned in step (e) with a malic acid solution; in step (f), the malic acid solution has a concentration of 0.8 wt%-1.2 wt%, and the malic acid solution is cleaned at a flow rate of 100-150 L / h for 15-25 min; (g) rinsing the reverse osmosis membrane cleaned in step (f) with pure water until neutral.

2. The method of claim 1, wherein the method is characterized by, In step (a), the pure water is rinsed at a flow rate of 80-120 L / h for 10-20 min.

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