A process for recycling DMF and deionized water in reverse osmosis membrane production

Abstract

The present invention provides a process for recycling DMF and deionized water in a reverse osmosis membrane production process, which mainly includes: subjecting low-concentration waste liquid in an organic wastewater collection tank to reverse osmosis through a reverse osmosis membrane assembly, separating part of the deionized water into a deionized water recovery tank, and forming a concentrated liquid from the low-concentration waste liquid in the organic wastewater collection tank; when the concentration of the concentrated liquid reaches a preset value, the concentrated liquid is transported to a concentrated liquid distillation separator, where the concentrated liquid is distilled and separated into deionized water and a high-concentration DMF solvent; the deionized water is transported to the deionized water recovery tank, and the high-concentration DMF solvent is transported to a DMF reflux tank. The DMF and deionized water used in the production process of the porous polymer-based membrane according to the present invention can be recycled and reused at a rate of more than 99%, achieving zero emission and zero pollution, and only consuming the substrate and high molecular weight polymer during the production process.

Description

Technical Field

[0001] The invention relates to the technical field of reverse osmosis membrane production, in particular to a recycling process of DMF and deionized water in a reverse osmosis membrane production process. Background Art

[0002] Currently, reverse osmosis membrane technology is widely used in water treatment for applications such as water purification, industrial water treatment, superdeionized water production, and seawater desalination. The porous polymer-based membrane is one of the primary components of a reverse osmosis membrane. The porous polymer-based membrane is formed from a polymer, but the polymer itself is insoluble in water. Therefore, the polymer must be dissolved in a water-soluble solvent. After the porous polymer-based membrane is formed, it is then soaked and cleaned with deionized water to separate the solvent from the porous supporting polymer-based membrane. This solvent is typically dimethylformamide (DMF), which is toxic and cannot be discharged directly. During the reverse osmosis membrane production process, DMF must be recycled. Currently, no literature discloses a method for fully recycling DMF during reverse osmosis membrane production, making zero emissions impossible. Summary of the Invention

[0003] The technical problem to be solved by the embodiments of the present invention is to provide a recycling process for DMF and deionized water in the reverse osmosis membrane production process, which can realize the full-cycle recycling and utilization of dimethylformamide and deionized water in the production link of the porous polymer base membrane of the reverse osmosis membrane, and solve the problem that the existing technology is difficult to recover dimethylformamide and cannot be directly recycled when soaking the porous polymer base membrane.

[0004] In order to solve the above technical problems, the present invention provides a process for recycling DMF and deionized water in a reverse osmosis membrane production process, comprising:

[0005] Step A1, forming a porous polymer base membrane on a substrate, and soaking the porous polymer base membrane in deionized water in a polymer base membrane soaking tank;

[0006] Step A2: removing the substrate with the porous polymer base film, forming a low-concentration waste liquid of DMF solvent and deionized water, and injecting the low-concentration waste liquid into an organic wastewater collection tank;

[0007] Step B1, performing reverse osmosis on the low-concentration waste liquid in the organic wastewater collection tank through a reverse osmosis membrane assembly, separating a portion of the deionized water into a deionized water recovery tank, and forming a concentrated solution from the low-concentration waste liquid in the organic wastewater collection tank;

[0008] Step B2: When the concentration of the concentrate reaches a preset value, the concentrate is transported to a concentrate distillation separator, where the concentrate is distilled and separated into deionized water and a high-concentration DMF solvent. The deionized water is transported to a deionized water recovery tank, and the high-concentration DMF solvent is transported to a DMF reflux tank.

[0009] Step C: transporting the deionized water in the deionized water recovery tank to the polymer base film soaking tank in step A1; at the same time, mixing the high-concentration DMF solvent in the DMF reflux tank with the high molecular polymer and circulating it to step A1.

[0010] The step A1 forms a porous polymer base film on the substrate, comprising providing a substrate, a polymer, and a DMF solvent, dissolving the polymer in the DMF solvent to form a polymer solution, and then forming the porous polymer base film on the substrate by liquid-solid phase conversion of the polymer solution;

[0011] The substrate is a polyester substrate produced by a wet process; and the high molecular polymer is polysulfone.

[0012] The polymer solution is formed by dissolving the polymer in the DMF solvent, wherein the polymer is added to the DMF solvent, stirred at 120° C. for more than 12 hours until the polymer is completely dissolved, and then the solution is vacuumed for more than 12 hours to obtain the polymer solution.

[0013] The high molecular weight polymer and DMF solvent are calculated according to the mass percentage concentration: high molecular weight polymer 15-20%, DMF solvent 80-85%.

[0014] In step B2, the preset value is 20-30%, and the content of the high-concentration DMF solvent is above 99%.

[0015] Based on step A2, the method further includes step A3: forming a desalination layer on the porous polymer-based membrane.

[0016] Specifically, the method comprises: washing the porous polymer base membrane with an amine aqueous solution, an oily solution, and an alkali, then washing with pure water, washing with heat-treated pure water, and then soaking and drying with a moisturizing agent glycerin to form a desalting layer.

[0017] The amine aqueous solution contains, in terms of mass percentage concentration, 1.5-4.5% of m-phenylenediamine, 1-5% of triethylamine hydrochloride, 0.01-0.05% of sodium hydroxide, and 0.01-0.2% of sodium bisulfite.

[0018] The oil phase solution comprises, in terms of mass percentage concentration, 0.1-0.28% of trimesoyl chloride, tripropyl phosphate, and an organic solvent as the balance.

[0019] The substrate with the porous polymer base membrane is immersed in an amine aqueous solution for 0.3-5 minutes, the excess aqueous phase is squeezed out, and then the oil phase solution is coated for 0.3-2 minutes for interface reaction, and then immersed in alkali washing for 0.5-2 minutes, hot water setting for 10-30 minutes, and glycerin moisturizing for 0.5-2 minutes to form a desalting layer on the surface of the porous polymer base membrane.

[0020] Based on step A3, the method further includes step A4, forming a scale inhibition layer on the surface of the desalination layer by cross-linking and grafting a second polymer.

[0021] Specifically, the method comprises the following components in the following mass percentage concentrations: polyaspartic acid 0.1-2%, cross-linking agent hexamethylenediamine 0.1-1%, buffer potassium dihydrogen phosphate / tripotassium phosphate 0.01-0.1%, catalyst 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride (DMTMM) 0.1%-1%, and pure water as the balance.

[0022] The present invention provides a process for recycling DMF and deionized water in the production process of reverse osmosis membranes. The DMF and deionized water used in the production of porous polymer-based membranes can be recycled and reused at a rate of more than 99%, achieving zero emissions and zero pollution. Only the base material and high molecular weight polymer need to be consumed during the production process, thus forming a zero-emission, highly environmentally friendly production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the overall process structure in an embodiment of the present invention.

[0024] In the picture:

[0025] 1 is the outlet valve of the reverse osmosis concentrated water lift pump; 2 is the reverse osmosis concentrated water lift pump; 3 is the inlet valve of the reverse osmosis concentrated water lift pump; 4 is the organic wastewater collection tank; 5 is the inlet valve of the reverse osmosis raw water lift pump; 6 is the reverse osmosis raw water lift pump; 7 is the outlet valve of the reverse osmosis raw water lift pump; 8 is the reverse osmosis system safety filter; 9 is the safety filter drain valve; 10 is the inlet valve of the reverse osmosis high-pressure pump; 11 is the reverse osmosis high-pressure pump; 12 is the outlet valve of the reverse osmosis high-pressure pump; 13 is the check valve of the reverse osmosis flushing port; 14 is the reverse osmosis flushing on-off valve; 15 is the reverse osmosis flushing port; 16 is the first reverse osmosis membrane assembly; 17 It is the second reverse osmosis membrane assembly; 18 is the first reverse osmosis membrane permeate sampling valve; 19 is the second reverse osmosis membrane permeate sampling valve; 20 is the reverse osmosis flushing permeate section discharge valve; 21 is the reverse osmosis permeate control valve; 22 is the deionized water recovery tank; 23 is the reverse osmosis flushing retentate section discharge valve; 24 is the reverse osmosis retentate control valve; 25 is the concentrated liquid distillation separator; 26 is the circulating liquid return port; 27 is the DMF waste liquid injection port; 28 is the polymer storage container; 29 is the DMF solvent tank; 30 is the liquid-solid phase conversion tank; 31 is the polymer base membrane soaking tank; 32 is the DMF reflux tank. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] like Figure 1As shown, an embodiment of the present invention provides a process for reverse osmosis membrane production, wherein the main structures include: an organic wastewater collection tank 4, a reverse osmosis raw water lifting pump 6, a reverse osmosis system security filter 8, a reverse osmosis high-pressure pump 11, a first reverse osmosis membrane assembly 16, a second reverse osmosis membrane assembly 17, a concentrate distillation separator 25, a DMF reflux tank 32, a polymer storage container 28, a DMF solvent tank 29, a liquid-solid phase conversion tank 30, a polymer base membrane soaking tank 31, and a deionized water recovery tank 22.

[0030] Among them, the organic wastewater collection tank 4 is used to collect DMF deionized water waste liquid or other organic waste liquid;

[0031] The reverse osmosis raw water boost pump 6 is used to supply the DMF deionized water waste liquid to the reverse osmosis system security filter 8;

[0032] The reverse osmosis system security filter 8 can filter and treat the DMF deionized water waste liquid;

[0033] The reverse osmosis high-pressure pump 11 is used to pressurize and transport the DMF deionized water waste liquid to the reverse osmosis membrane assembly;

[0034] The first reverse osmosis membrane assembly 16 and the second reverse osmosis membrane assembly 17 are respectively used to separate and treat the DMF deionized water waste liquid;

[0035] The concentrated liquid distillation separator 25 is used to distill the concentrated liquid to remove the deionized water, thereby further purifying the DMF solvent in the concentrated liquid to more than 99%;

[0036] The DMF reflux tank 32 is connected to the concentrate distillation separator 25 and is used to store the distilled and purified DMF solvent and to supply the DMF solvent to the DMF solvent tank 29;

[0037] The polymer storage container 28 is used to store the high molecular weight polymer and supply the high molecular weight polymer to the DMF solvent tank 29;

[0038] The DMF solvent tank 29 is used to dissolve the high molecular polymer in the DMF solvent, which has high temperature heating and stirring functions;

[0039] The liquid-solid phase conversion tank 30 is used for coating the polymer solution on the substrate;

[0040] The polymer base film soaking tank 31 is filled with deionized water for soaking the substrate with the porous polymer base film to dissolve the excess DMF solvent in the deionized water;

[0041] The deionized water recovery tank 22 is used to recover deionized water and deliver the deionized water to the polymer base film soaking tank.

[0042] The organic wastewater collection tank 4 is connected to the reverse osmosis system security filter 8 through the reverse osmosis raw water lifting pump 6, and the reverse osmosis system security filter 8 is connected to the raw liquid inlet of the reverse osmosis membrane assembly through the reverse osmosis high-pressure pump 11. The retained liquid outlet of the reverse osmosis membrane assembly is refluxed to the organic wastewater collection tank 4 through the pipeline; the permeate outlet of the reverse osmosis membrane assembly is connected to the deionized water recovery tank 22, and the organic wastewater collection tank 4 is also connected to the polymer base membrane soaking tank 31 through the DMF waste liquid injection port 27. The organic wastewater collection tank 4 is connected to the first reverse osmosis membrane assembly 16 through the circulation liquid return port 26. And the retained liquid outlet of the second reverse osmosis membrane assembly 17; the inlet of the concentrated liquid distillation separator 25 is connected to the organic wastewater collection tank 4 through the reverse osmosis concentrated water lifting pump 2, and the concentrated liquid distillation separator 25 has two outlets, one is the deionized water outlet, and the other is the DMF solvent outlet. The deionized water outlet is connected to the inlet of the deionized water recovery tank 22, and the DMF solvent outlet is connected to the inlet of the DMF reflux tank 32; the DMF reflux tank 32 and the polymer storage container 28 are respectively connected to the DMF solvent tank 29; the outlet of the deionized water recovery tank 22 is connected to the polymer base membrane soaking tank 31.

[0043] The DMF waste liquid injection port 27 is used to inject the DMF deionized water waste liquid into the organic wastewater collection tank 4. The concentrated liquid distillation separator 25 can discharge the concentrated liquid of the DMF deionized water waste liquid after the DMF deionized water waste liquid is concentrated to a set value in the entire recovery and treatment system (usually supply it to a distillation device for further concentration).

[0044] In this embodiment, two reverse osmosis membrane assemblies are provided, namely a first reverse osmosis membrane assembly 16 and a second reverse osmosis membrane assembly 17. The first reverse osmosis membrane assembly 16 and the second reverse osmosis membrane assembly 17 are connected in parallel. The two reverse osmosis membrane assemblies are installed in parallel in the recycling and processing system, so that the operating mode of either reverse osmosis membrane assembly can be set as needed. For example, one reverse osmosis membrane assembly can be selected to operate while the other is inactive, or both reverse osmosis membrane assemblies can be selected to operate simultaneously.

[0045] A first reverse osmosis membrane permeate sampling valve 18 is installed on the permeate outlet pipeline of the first reverse osmosis membrane assembly 16 for sampling and testing the permeate from the first reverse osmosis membrane assembly 16. A second reverse osmosis membrane permeate sampling valve 19 is installed on the permeate outlet pipeline of the second reverse osmosis membrane assembly 17 for sampling and testing the permeate from the second reverse osmosis membrane assembly 17. The first reverse osmosis membrane permeate sampling valve 18 allows for continuous testing of the purity of the permeate from the first reverse osmosis membrane assembly 16, while the second reverse osmosis membrane permeate sampling valve 19 allows for continuous testing of the purity of the permeate from the second reverse osmosis membrane assembly 17, providing sampling data to the control center.

[0046] The organic wastewater collection tank 4 is connected to the concentrated liquid distillation separator 25 through a reverse osmosis concentrated water lift pump 2, and a reverse osmosis concentrated water lift pump inlet valve 3 is provided on the upstream pipeline of the reverse osmosis concentrated water lift pump 2, and a reverse osmosis concentrated water lift pump outlet valve 1 is provided on the downstream pipeline.

[0047] The upstream pipeline of the reverse osmosis raw water lift pump 6 is provided with a reverse osmosis raw water lift pump inlet valve 5, and the downstream pipeline is provided with a reverse osmosis raw water lift pump outlet valve 7. The reverse osmosis raw water lift pump inlet valve 5 and the reverse osmosis raw water lift pump outlet valve 7 can cooperate with the reverse osmosis raw water lift pump 6 to work.

[0048] The upstream pipeline of the reverse osmosis high-pressure pump 11 is provided with a reverse osmosis high-pressure pump inlet valve 10, and the downstream pipeline is provided with a reverse osmosis high-pressure pump outlet valve 12. The reverse osmosis high-pressure pump inlet valve 10 and the reverse osmosis high-pressure pump outlet valve 12 can cooperate with the reverse osmosis high-pressure pump 11 to work.

[0049] The reverse osmosis membrane assembly's raw liquid inlet is also connected to a reverse osmosis flushing port 15. A reverse osmosis flushing port check valve 13 and a reverse osmosis flushing on-off valve 14 are installed in the pipeline between the reverse osmosis membrane assembly's raw liquid inlet and the reverse osmosis flushing port 15. The reverse osmosis flushing port 15 is used to connect to an external backwashing device, allowing external backwashing liquid to enter the reverse osmosis membrane assembly, thereby backwashing the reverse osmosis membrane and other components within the reverse osmosis membrane assembly. To prevent backflow of the cleaning liquid during the backwashing process, the reverse osmosis flushing port check valve 13 and the reverse osmosis flushing on-off valve 14 are installed in the pipeline to ensure a smooth backwashing process.

[0050] The reverse osmosis membrane module's permeate outlet pipeline is equipped with a reverse osmosis permeate control valve 21, and a reverse osmosis flushing permeate section drain valve 20 is installed on a branch of the reverse osmosis membrane module's permeate outlet pipeline. The reverse osmosis permeate control valve 21 controls the flow of reverse osmosis permeate in the pipeline; the reverse osmosis flushing permeate section drain valve 20 allows the reverse osmosis permeate to be discharged.

[0051] A reverse osmosis retentate control valve 24 is provided on the retentate outlet pipeline of the reverse osmosis membrane assembly, and a reverse osmosis flushing retentate section discharge valve 23 is provided on a branch of the retentate outlet pipeline of the reverse osmosis membrane assembly.

[0052] The embodiment of the present invention provides a process for recycling DMF and deionized water in a reverse osmosis membrane production process, comprising:

[0053] Step A1: forming a porous polymer base membrane on a substrate (usually a non-woven fabric), specifically by dissolving a polymer in a DMF solvent to form a polymer solution, then forming the porous polymer base membrane on the substrate through liquid-solid phase conversion of the polymer solution, and soaking the porous polymer base membrane in deionized water in a polymer base membrane soaking tank 31. The deionized water can dissolve the DMF solvent;

[0054] Step A2: taking out the substrate with the porous polymer base film, forming a low-concentration waste liquid of DMF solvent and deionized water, and injecting the low-concentration waste liquid into the organic wastewater collection tank 4;

[0055] Step B1, the low-concentration waste liquid in the organic wastewater collection tank 4 is subjected to reverse osmosis through the first reverse osmosis membrane assembly 16 and the second reverse osmosis membrane assembly 17, and a portion of the deionized water is separated into the deionized water recovery tank 22, so that the low-concentration waste liquid in the organic wastewater collection tank 4 is formed into a high-concentration concentrated liquid, and the concentration of the concentrated liquid can reach 20-30% or even higher. That is, in this step, the low-concentration waste liquid is reverse osmosis through the reverse osmosis membrane, so that a portion of the deionized water is separated out, and the concentration of the low-concentration waste liquid is increased;

[0056] Step B2: When the concentration of the concentrate reaches a preset value (e.g., 20%, 25%, 30% or other values), the concentrate is transported to the concentrate distillation separator 25, where the concentrate is distilled and separated into deionized water and a high-concentration DMF solvent (with a concentration of 99% or more). The deionized water is transported to the deionized water recovery tank 22, and the high-concentration DMF solvent is transported to the DMF reflux tank 32.

[0057] Step C: The deionized water in the deionized water recovery tank 22 is transported to the polymer-based membrane soaking tank in step A1; at the same time, the high-concentration DMF solvent in the DMF reflux tank 32 is mixed with the high molecular polymer and circulated to step A1; thereby achieving full recycling and reuse of the DMF solvent and deionized water in the porous polymer-based membrane forming process of the reverse osmosis membrane.

[0058] In actual operation, the deionized water recovery tank 22 and the DMF reflux tank 32 are also provided with a liquid replenishing port to replenish the trace amount of DMF solvent and deionized water carried by the substrate during the production process.

[0059] The substrate is a polyester substrate produced by a wet process; and the high molecular polymer is polysulfone.

[0060] In step A1, the polymer is dissolved in DMF solvent to form a polymer solution. The polymer is added to the DMF solvent, stirred at 120° C. for more than 12 hours until the polymer is completely dissolved, and then the solution is vacuumed for more than 12 hours to obtain a polymer solution.

[0061] The high molecular weight polymer and DMF solvent are calculated according to the mass percentage concentration: high molecular weight polymer 15-20%, DMF solvent 80-85%.

[0062] The reverse osmosis membrane production process further comprises step A3, forming a desalination layer on the porous polymer base membrane, based on step A2.

[0063] Specifically, the method comprises: washing the porous polymer base membrane with an amine aqueous solution, an oily solution, and an alkali, then washing with pure water, washing with heat-treated pure water, and then soaking and drying with a moisturizing agent glycerin to form a desalting layer.

[0064] The amine aqueous solution contains, in terms of mass percentage concentration, 1.5-4.5% of m-phenylenediamine, 1-5% of triethylamine hydrochloride, 0.01-0.05% of sodium hydroxide, and 0.01-0.2% of sodium bisulfite.

[0065] The oil phase solution comprises, in terms of mass percentage concentration, 0.1-0.28% of trimesoyl chloride, tripropyl phosphate, and an organic solvent as the balance.

[0066] The substrate with the porous polymer base membrane is immersed in an amine aqueous solution for 0.3-5 minutes, the excess aqueous phase is squeezed out, and then the oil phase solution is coated for 0.3-2 minutes for interface reaction, and then immersed in alkali washing for 0.5-2 minutes, hot water setting for 10-30 minutes, and glycerin moisturizing for 0.5-2 minutes to form a desalting layer on the surface of the porous polymer base membrane.

[0067] The reverse osmosis membrane production process further includes step A4, based on step A3, forming a scale inhibition layer on the surface of the desalination layer by cross-linking and grafting a second polymer.

[0068] Specifically, the method comprises the following components in the following mass percentage concentrations: polyaspartic acid 0.1-2%, cross-linking agent hexamethylenediamine 0.1-1%, buffer potassium dihydrogen phosphate / tripotassium phosphate 0.01-0.1%, catalyst 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride (DMTMM) 0.1%-1%, and pure water as the balance.

[0069] The present invention adopts DMTMM as a catalyst to enable polyaspartic acid to react with a cross-linking agent, thereby forming a scale inhibition layer on the surface of the desalination layer to play a scale inhibition role.

[0070] In this embodiment, a mixed solution containing polyaspartic acid, hexamethylenediamine, a buffer, and a catalyst is coated on the desalination layer, and a scale inhibition layer of an integrated composite reverse osmosis water purification membrane is formed under weak alkalinity and high temperature thermal cross-linking reaction. The cross-linked polyaspartic acid molecular structure contains alternating polyamide bonds, which can form a complex with calcium and magnesium ions in the running water, effectively reducing the flux reduction and blockage caused by ion precipitation. Furthermore, through the charge of the carboxyl and amino groups on the polyamide bonds, the electrostatic interaction is used to reduce the attraction between the particles, preventing aggregation and deposition. At the same time, the molecule exists in a chain structure, which can adsorb micro-solids deposited in the water, inhibit their growth, and dissolve in water together after adsorption. Ultimately, it can greatly delay the attenuation of membrane performance and long-term operational stability, bringing customers a high-quality experience.

[0071] The present invention provides a process for recycling DMF and deionized water in the production process of reverse osmosis membranes. The DMF and deionized water used in the production of porous polymer-based membranes can be recycled and reused at a rate of more than 99%, achieving zero emissions and zero pollution. Only the base material and high molecular weight polymer need to be consumed during the production process, thus forming a zero-emission, highly environmentally friendly production process.

[0072] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A process for recycling DMF and deionized water in a reverse osmosis membrane production process, characterized in that: include: Step A1, forming a porous polymer base membrane on a substrate, and soaking the porous polymer base membrane in deionized water in a polymer base membrane soaking tank; Step A2: removing the substrate with the porous polymer base film, forming a low-concentration waste liquid of DMF solvent and deionized water, and injecting the low-concentration waste liquid into an organic wastewater collection tank; Step A3, forming a desalting layer on the porous polymer base membrane; Step A4, forming a scale inhibition layer on the surface of the desalination layer by cross-linking and grafting a second polymer; The second polymer is polyaspartic acid; The anti-scaling layer is composed of the following components in a cross-linked grafting manner in a mass percentage concentration: polyaspartic acid 0.1-2%, cross-linking agent hexamethylenediamine 0.1-1%, buffer potassium dihydrogen phosphate / tripotassium phosphate 0.01-0.1%, catalyst 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride (DMTMM) 0.1%-1%, and pure water as the balance; Step B1, performing reverse osmosis on the low-concentration waste liquid in the organic wastewater collection tank through a reverse osmosis membrane assembly, separating a portion of the deionized water into a deionized water recovery tank, and forming a concentrated solution from the low-concentration waste liquid in the organic wastewater collection tank; Step B2: When the concentration of the concentrate reaches a preset value, the concentrate is transported to a concentrate distillation separator, where the concentrate is distilled and separated into deionized water and a high-concentration DMF solvent. The deionized water is transported to a deionized water recovery tank, and the high-concentration DMF solvent is transported to a DMF reflux tank. Step C: transporting the deionized water in the deionized water recovery tank to the polymer base film soaking tank in step A1; at the same time, mixing the high-concentration DMF solvent in the DMF reflux tank with the high molecular polymer and circulating it to step A1.

2. The recycling process according to claim 1, characterized in that: The step A1 forms a porous polymer base film on the substrate, comprising providing a substrate, a polymer, and a DMF solvent, dissolving the polymer in the DMF solvent to form a polymer solution, and then forming the porous polymer base film on the substrate by liquid-solid phase conversion of the polymer solution; The substrate is a polyester substrate produced by a wet process; and the high molecular polymer is polysulfone.

3. The recycling process according to claim 2, characterized in that: The polymer solution is formed by dissolving the polymer in the DMF solvent, wherein the polymer is added to the DMF solvent, stirred at 120° C. for more than 12 hours until the polymer is completely dissolved, and then vacuuming the solution for more than 12 hours to obtain the polymer solution.

4. The recycling process according to claim 2, characterized in that: The high molecular weight polymer and DMF solvent are calculated according to the mass percentage concentration: high molecular weight polymer 15-20%, DMF solvent 80-85%.

5. The recycling process according to claim 1, characterized in that: In step B2, the preset value is 20-30%, and the content of the high-concentration DMF solvent is above 99%.

6. The recycling process according to claim 1, characterized in that: Step A3 specifically includes: washing the porous polymer base membrane with an amine aqueous solution, an oily solution, and an alkali, then washing with pure water, heat-treating the pure water, and then soaking and drying with a moisturizing agent glycerin to form a desalting layer.

7. The recycling process according to claim 6, characterized in that: The amine aqueous solution comprises, by mass percentage, 1.5-4.5% of m-phenylenediamine, 1-5% of triethylamine hydrochloride, 0.01-0.05% of sodium hydroxide, and 0.01-0.2% of sodium bisulfite; The oil phase solution comprises, in terms of mass percentage concentration, 0.1-0.28% of trimesoyl chloride, tripropyl phosphate, and an organic solvent as the balance.

8. The recycling process according to claim 6, characterized in that: The substrate with the porous polymer base membrane is immersed in an amine aqueous solution for 0.3-5 minutes, the excess aqueous phase is squeezed out, and then the oil phase solution is coated for 0.3-2 minutes for interface reaction, and then immersed in alkali washing for 0.5-2 minutes, hot water setting for 10-30 minutes, and glycerin moisturizing for 0.5-2 minutes to form a desalting layer on the surface of the porous polymer base membrane.

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