MBR membrane sewage treatment membrane and preparation method thereof

Abstract

The invention relates to the technical field of sewage treatment, and discloses an MBR (Membrane Biological Reactor) sewage treatment membrane and a preparation method thereof, the preparation method comprises the following steps: step 1, dissolving and mixing; step 2, adding a functional auxiliary agent; step 3, defoaming treatment; step 4, film forming; 5, heat treatment; and step 6, cooling and curing. The volatility of DMAc is relatively low, the volatilization speed in the film forming process is relatively slow, residual volatile matter can be reduced after the film is cured, PVDF and PES can be well dissolved, uniform dispersion of a polymer is ensured, and therefore the overall quality and stability of the film are improved; the mold is placed in the environment with the temperature of 20-30 DEG C and the humidity of 30%-50%, DMAc in the polymer solution is gradually volatilized, and the beneficial effect that volatile matter cannot be released due to secondary injection molding after the treatment film is prepared is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to an MBR membrane sewage treatment membrane and a preparation method thereof. Background Art

[0002] MBR membrane-bioreactor is a new type of wastewater treatment system that organically combines membrane separation technology with biological treatment technology. The main principle of MBR membrane is to use the tiny holes on the surface of MBR membrane to filter wastewater. During the filtration process, since the wastewater needs to be filtered through the MBR membrane, the particles in the wastewater will be isolated by the MBR membrane. Due to the pressure of the wastewater flow, the particles or pollutants will adhere to the MBR membrane and pollute the MBR membrane, which can easily cause the holes on the surface of the MBR membrane to be blocked by particles or pollutants.

[0003] After searching the prior art, a MBR membrane sewage treatment membrane and its preparation method with the publication number of CN 116332337 A were found. The method includes the following steps: Step 1: multiple MBR membrane tubes are placed between multiple arc clamps for clamping, and the two ends of the multiple MBR membrane tubes are respectively extended between the two arc cavities on both sides; Step 2: the two arc cavities on both sides are interlocked, and the ends of the multiple MBR membrane tubes between the two arc cavities are injection molded and fixed; Step 3: the ends of the multiple MBR membrane tubes are injection molded to form a connecting seat and a rotating seat; A MBR membrane sewage treatment membrane includes a placement frame, multiple treatment modules are placed in the placement frame, and the multiple treatment modules are connected through a water outlet pipe; Prepare a MBR membrane sewage treatment membrane with a certain self-cleaning ability. The above technical defects are solved.

[0004] The above technical solution enables the treatment membrane to have self-cleaning ability through structural improvement, but the MBR membrane is usually made of polymer materials, such as polyvinylidene fluoride (PVDF), polyethersulfone (PES) and polysulfone (PS), and in step 2, the ends of multiple MBR membrane tubes are fixed between the arc cavities by injection molding. The injection molding process usually involves high temperature and high pressure. High temperature decomposition or side reactions produce organic volatiles, including formaldehyde and phenol. These volatiles are released into the environment through the membrane tubes, affecting the sewage treatment effect or causing secondary pollution to the environment. At the same time, the polymer decomposes at high temperature to produce low molecular weight degradation products including hydroxyl compounds and acid degradation products. These products will also affect the mechanical properties and chemical stability of the membrane tube. Summary of the invention

[0005] Technical issues solved:

[0006] In view of the deficiencies in the prior art, the present invention provides an MBR membrane sewage treatment membrane and a preparation method thereof, which has the advantages that the treatment membrane will not release volatiles due to secondary injection molding after preparation, and the products of decomposition of the treatment membrane at high temperature will not cause corrosion, thereby solving the problems of the above-mentioned technologies.

[0007] Technical solution:

[0008] To achieve the above object, the present invention provides the following technical solution: an MBR membrane sewage treatment membrane, wherein the treatment membrane is composed of the following components in weight ratio:

[0009]

[0010] The antioxidant is phenol; the anti-thermal decomposition agent is hindered amine; and the anti-corrosion agent is nitrate.

[0011] A method for preparing an MBR membrane for wastewater treatment, the method being used to prepare the treatment membrane according to claim 1, the method comprising the following steps:

[0012] Step 1, dissolving and mixing: select N,N-dimethylacetamide DMAc, preheat it to 60-80°C in a stirrer, gradually add polyvinylidene fluoride PVDF and polyether sulfone PES into the preheated solvent in the required proportion, and continue stirring to form a uniform polymer solution;

[0013] Step 2: Adding functional additives: After the polymer is completely dissolved, add antioxidants, anti-thermal decomposition agents, anti-corrosion agents, low-volatility plasticizers and lubricants in sequence;

[0014] Step 3: Degassing: while stirring, remove bubbles from the mixture by vacuum or ultrasonic treatment;

[0015] Step 4: Film forming: pour the degassed polymer solution into a pre-prepared mold to form the basic form of the film. By controlling the ambient temperature and humidity, the solvent in the mixed solution gradually evaporates from the film, resulting in film formation.

[0016] Step 5, heat treatment: heat treatment of the formed film to further promote cross-linking of the polymer and improve the film's resistance to thermal decomposition, at a temperature of 150-200°C for 30 minutes to 1 hour;

[0017] Step 6: Cooling and curing: Slowly cool the heat-treated film to room temperature and cure it in a static environment for 24 hours to ensure that the film material is completely stable.

[0018] Preferably, the weight ratio of N,N-dimethylacetamide is 3-7 times that of polyvinylidene fluoride.

[0019] Preferably, the detailed steps of step 1 are:

[0020] S1.1. Material preparation: polyvinylidene fluoride PVDF; polyether sulfone PES; N,N-dimethylacetamide;

[0021] S1.2, heating the solvent: add the required amount of N,N-dimethylacetamide into the container of the stirrer, turn on the heating stirrer, heat N,N-dimethylacetamide to 60-80°C, and monitor with a thermometer;

[0022] S1.3, gradually add polymer: slowly add 57 g of PVDF into the heated N,N-dimethylacetamide solvent, and continue stirring for 10-20 minutes to ensure that PVDF is completely dissolved;

[0023] S1.4, continue to add polyethersulfone PES: Next, gradually add 22 grams of polyethersulfone PES to the dissolved PVDF, and continue stirring for 10-20 minutes to ensure uniform mixing;

[0024] S1.5, dissolution complete: At this temperature, the polymer is completely dissolved. If undissolved polymer is found, extend the stirring time by 10%;

[0025] S1.6. Maintain liquid state: After dissolution is completed, keep the solution warm to prevent the temperature from dropping and causing the polymer to precipitate again. Continue stirring at a low speed of 50-100 rpm to ensure uniformity.

[0026] Preferably, the detailed steps in step 2 are:

[0027] S2.1, antioxidant: slowly add the antioxidant into the polymer solution, stirring for 5-10 minutes;

[0028] S2.2, anti-thermal decomposition agent: Then, add 4 grams of anti-thermal decomposition agent and continue stirring for 5-10 minutes;

[0029] S2.3, anti-corrosion agent: then add 3 grams of anti-corrosion agent;

[0030] S2.4, low volatility plasticizer: add 2 g of low volatility plasticizer and stir for 5-10 minutes;

[0031] S2.5, Lubricant: Finally, add 1 gram of lubricant and keep stirring until all ingredients are evenly mixed;

[0032] S2.6. After all additives have been added, continue stirring the solution for about 10 minutes.

[0033] Preferably, the detailed steps in step 4 are:

[0034] S3.1, casting polymer solution: pour the degassed polymer solution evenly into the prepared mold to form a uniform film layer with a thickness of 30-200 microns;

[0035] S3.2, Volatilization and film formation: Place the mold in a controlled environment: temperature: 20-30℃, humidity: 30%-50%;

[0036] S3.3. Control the volatilization rate: Continuously monitor the ambient temperature and humidity. The DMAc in the polymer solution will gradually evaporate and the film will be formed in 24-72 hours.

[0037] Preferably, the detailed steps of step 5 are:

[0038] S5.1. Preheating equipment: Before starting the heat treatment, preheat the oven to 150-200°C as an intermediate value for the experiment. The preheating time is 15-30 minutes until the equipment stabilizes at the preset temperature.

[0039] S5.2. Film placement: Carefully place the dried film on a flat tray in the oven, ensuring that the film does not overlap during heating and that there is adequate air circulation in the oven to promote uniform heating;

[0040] S5.3, heat treatment time: keep the film in the oven for 30 minutes to 1 hour;

[0041] S5.4. Monitoring process: During the heat treatment process, ensure that the temperature of the oven is regularly monitored to prevent overheating or temperature fluctuations. Check every 10-15 minutes.

[0042] S5.5. Heat treatment is completed: After the heat treatment time is up, turn off the oven and let the film cool naturally to room temperature in the oven.

[0043] Preferably, the total mass of the polymer in step 1 is calculated as follows:

[0044] M total =M PVDF +M PES

[0045] Where: M total is the total mass of the polymer; M PVDF is the mass of polyvinylidene fluoride; M PES It is the quality of polyethersulfone.

[0046] Preferably, the ratio of each polymer in step 1 is calculated as:

[0047]

[0048] Where: C PVDF is the mass proportion of polyvinylidene fluoride in the mixture; CPES is the mass proportion of polyethersulfone in the mixture.

[0049] Preferably, the amount of each additive added in step 2 is calculated as:

[0050] M additive =M solution ×C additive

[0051] Where: M solution is the total mass of the polymer solution; M additive is the quality of the additive; C additive is the mass ratio of the additive.

[0052] Compared with the prior art, the present invention provides an MBR membrane sewage treatment membrane and a preparation method thereof, which has the following beneficial effects:

[0053] 1. The present invention has low volatility of DMAc, and its volatilization speed is relatively slow during the film forming process, which helps to reduce residual volatiles after the film is solidified, can dissolve PVDF and PES well, ensure the uniform dispersion of polymers, and thus improve the overall quality and stability of the film. During the film forming process, by placing the mold in an environment with a temperature of 20-30° C. and a humidity of 30%-50%, the DMAc in the polymer solution is gradually volatilized, which effectively avoids the volatiles from being released again in the later injection molding process. When the polymer solution is degassed, the bubbles in the mixture are removed by applying vacuum or ultrasound, which helps to reduce the possible accumulation of volatiles in the subsequent processing. The heat treatment promotes the cross-linking reaction between the polymers, thereby improving the mechanical strength and air tightness of the film, which helps to block the release of volatiles. The high temperature during the heat treatment process helps to further evaporate any residual DMAc, ensuring that the volatile components of the final film are reduced to a minimum, achieving the beneficial effect that the treated film will not release volatiles due to secondary injection molding after the preparation is completed.

[0054] 2. The present invention selects polyvinylidene fluoride (PVDF) and polyether sulfone (PES) as main polymer materials in the preparation of MBR membrane. PVDF has strong tolerance to many chemicals. When it decomposes at high temperature, it releases relatively less gas and solid residue, and does not produce highly corrosive compounds. PVDF has a high thermal decomposition temperature and can remain stable at relatively high temperatures, reducing the risk of chemical corrosion. In the preparation process of the membrane, functional additives such as antioxidants, anti-thermal decomposition agents and anti-corrosion agents are added to ensure that under high temperature conditions, the polymer will not accelerate decomposition due to oxidation, thereby reducing the corrosive products generated during the decomposition process, and can improve its heat resistance when the membrane is affected by high temperature conditions, reduce the generation of decomposition products and control the corrosiveness of the products. By heat treating the membrane at 150-200°C, cross-linking between polymers is promoted, thereby improving the structural stability of the membrane. In the network structure of the membrane material, the higher the degree of cross-linking, the stronger its resistance to decomposition, the fewer decomposition products produced, and generally the toxicity and corrosiveness are also lower. Through effective heat treatment, most of the solvents, such as N,N-dimethylacetamide (DMAc), are removed to further reduce the volatile organic compounds (VOCs) during membrane decomposition. After heat treatment, the membrane is left to cure for 24 hours. The stronger molecular cross-linking structure can maintain structural integrity at high temperatures and reduce the generation of decomposition products. Long-term standing allows any remaining solvents or additives in the membrane to evaporate, thereby reducing the release of corrosive substances caused by desorption in subsequent use, achieving the beneficial effect of not causing corrosion when the products of membrane decomposition at high temperatures are treated. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The present invention is a schematic flow chart of the steps of the method for preparing the MBR membrane wastewater treatment membrane. DETAILED DESCRIPTION

[0056] 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.

[0057] See also Figure 1 , an MBR membrane sewage treatment membrane, the treatment membrane is composed of the following components in weight ratio:

[0058]

[0059] The antioxidant is phenol; the anti-thermal decomposition agent is hindered amine; and the anti-corrosion agent is nitrate.

[0060] A method for preparing an MBR membrane for wastewater treatment, the method being used to prepare the treatment membrane according to claim 1, the method comprising the following steps:

[0061] Step 1, dissolving and mixing: select N,N-dimethylacetamide DMAc, preheat it to 60-80°C in a stirrer, gradually add polyvinylidene fluoride PVDF and polyether sulfone PES into the preheated solvent in the required proportion, and continue stirring to form a uniform polymer solution;

[0062] Step 2: Adding functional additives: After the polymer is completely dissolved, add antioxidants, anti-thermal decomposition agents, anti-corrosion agents, low-volatility plasticizers and lubricants in sequence;

[0063] Step 3: Degassing: while stirring, remove bubbles from the mixture by vacuum or ultrasonic treatment;

[0064] Step 4: Film forming: pour the degassed polymer solution into a pre-prepared mold to form the basic form of the film. By controlling the ambient temperature and humidity, the solvent in the mixed solution gradually evaporates from the film, resulting in film formation.

[0065] Step 5, heat treatment: heat treatment of the formed film to further promote cross-linking of the polymer and improve the film's resistance to thermal decomposition, at a temperature of 150-200°C for 30 minutes to 1 hour;

[0066] Step 6: Cooling and curing: Slowly cool the heat-treated film to room temperature and cure it in a static environment for 24 hours to ensure that the film material is completely stable.

[0067] Using N,N-dimethylacetamide (DMAc) as a solvent has the following advantages:

[0068] Low volatility: DMAc has low volatility and evaporates relatively slowly during film formation, which helps to reduce residual volatiles after the film is cured.

[0069] Good solubility: It can dissolve PVDF and PES well, ensuring uniform dispersion of polymers, thereby improving the overall quality and stability of the membrane.

[0070] During the film forming process, the volatilization rate of DMAc is precisely controlled by environmental control (temperature and humidity), further reducing the release of volatiles:

[0071] Temperature and humidity settings: Place the mold in an environment with a temperature of 20-30°C and a humidity of 30%-50% to allow the DMAc in the polymer solution to evaporate gradually, which effectively prevents the volatiles from being released again during the subsequent injection molding process.

[0072] When degassing the polymer solution, air bubbles are removed from the mixture by applying vacuum or ultrasound. Although this step is mainly to improve the structure of the film, it also helps to reduce the possible accumulation of volatiles during subsequent processing.

[0073] The heat treatment step (150-200°C for 30 minutes to 1 hour) is key:

[0074] Promoting cross-linking reaction: Heat treatment promotes the cross-linking reaction between polymers, thereby improving the mechanical strength and air tightness of the film, which helps to block the release of volatiles.

[0075] Removal of residual solvent: The high temperatures during the thermal treatment process help to further evaporate any residual DMAc, ensuring that the final membrane contains minimal volatile components.

[0076] The functional additives added to the membrane, such as antioxidants, anti-thermal decomposition agents, and anti-corrosion agents, are carefully selected. Their presence not only improves the performance of the membrane (such as heat resistance and corrosion resistance), but also helps to seal the structure inside the membrane, reducing the chance of volatile release during later processing.

[0077] After the film is heat treated, it needs to be left to cure for 24 hours to ensure that the molecular structure of the film material is stable, thereby further ensuring that volatiles will not be easily released even during the secondary injection molding process.

[0078] Preferably, the weight ratio of N,N-dimethylacetamide is 3-7 times that of polyvinylidene fluoride.

[0079] Preferably, the detailed steps of step 1 are:

[0080] S1.1. Material preparation: polyvinylidene fluoride PVDF; polyether sulfone PES; N,N-dimethylacetamide;

[0081] S1.2, heating the solvent: add the required amount of N,N-dimethylacetamide into the container of the stirrer, turn on the heating stirrer, heat N,N-dimethylacetamide to 60-80°C, and monitor with a thermometer;

[0082] S1.3, gradually add polymer: slowly add 57 g of PVDF into the heated N,N-dimethylacetamide solvent, and continue stirring for 10-20 minutes to ensure that PVDF is completely dissolved;

[0083] S1.4, continue to add polyethersulfone PES: Next, gradually add 22 grams of polyethersulfone PES to the dissolved PVDF, and continue stirring for 10-20 minutes to ensure uniform mixing;

[0084] S1.5, dissolution complete: At this temperature, the polymer is completely dissolved. If undissolved polymer is found, extend the stirring time by 10%;

[0085] S1.6. Maintain liquid state: After dissolution is completed, keep the solution warm to prevent the temperature from dropping and causing the polymer to precipitate again. Continue stirring at a low speed of 50-100 rpm to ensure uniformity.

[0086] Preferably, the detailed steps in step 2 are:

[0087] S2.1, antioxidant: slowly add the antioxidant into the polymer solution, stirring for 5-10 minutes;

[0088] S2.2, anti-thermal decomposition agent: Then, add 4 grams of anti-thermal decomposition agent and continue stirring for 5-10 minutes;

[0089] S2.3, anti-corrosion agent: then add 3 grams of anti-corrosion agent;

[0090] S2.4, low volatility plasticizer: add 2 g of low volatility plasticizer and stir for 5-10 minutes;

[0091] S2.5, Lubricant: Finally, add 1 gram of lubricant and keep stirring until all ingredients are evenly mixed;

[0092] S2.6. After all additives have been added, continue stirring the solution for about 10 minutes.

[0093] Preferably, the detailed steps in step 4 are:

[0094] S3.1, casting polymer solution: pour the degassed polymer solution evenly into the prepared mold to form a uniform film layer with a thickness of 30-200 microns;

[0095] S3.2, Volatilization and film formation: Place the mold in a controlled environment: temperature: 20-30℃, humidity: 30%-50%;

[0096] S3.3. Control the volatilization rate: Continuously monitor the ambient temperature and humidity. The DMAc in the polymer solution will gradually evaporate and the film will be formed in 24-72 hours.

[0097] Preferably, the detailed steps of step 5 are:

[0098] S5.1. Preheating equipment: Before starting the heat treatment, preheat the oven to 150-200°C as an intermediate value for the experiment. The preheating time is 15-30 minutes until the equipment stabilizes at the preset temperature.

[0099] S5.2. Film placement: Carefully place the dried film on a flat tray in the oven, ensuring that the film does not overlap during heating and that there is adequate air circulation in the oven to promote uniform heating;

[0100] S5.3, heat treatment time: keep the film in the oven for 30 minutes to 1 hour;

[0101] S5.4. Monitoring process: During the heat treatment process, ensure that the temperature of the oven is regularly monitored to prevent overheating or temperature fluctuations. Check every 10-15 minutes.

[0102] S5.5. Heat treatment is completed: After the heat treatment time is up, turn off the oven and let the film cool naturally to room temperature in the oven.

[0103] Preferably, the total mass of the polymer in step 1 is calculated as follows:

[0104] M total =M PVDF +M PES

[0105] Where: M total is the total mass of the polymer; M PVDF is the mass of polyvinylidene fluoride; M PES It is the quality of polyethersulfone.

[0106] Preferably, the ratio of each polymer in step 1 is calculated as:

[0107]

[0108] Where: C PVDF is the mass proportion of polyvinylidene fluoride in the mixture; C PES is the mass proportion of polyethersulfone in the mixture.

[0109] Preferably, the amount of each additive added in step 2 is calculated as:

[0110] M additive =M solution ×C additive

[0111] Where: M solution is the total mass of the polymer solution; M additive is the quality of the additive; C additive is the mass ratio of the additive.

[0112] In the preparation of MBR membrane, polyvinylidene fluoride (PVDF) and polyethersulfone (PES) are selected as the main polymer materials. The characteristics of the two are as follows:

[0113] Polyvinylidene fluoride (PVDF):

[0114] Chemical resistance: PVDF has strong resistance to many chemicals. When it decomposes at high temperatures, it releases relatively little gas and solid residue and does not produce highly corrosive compounds.

[0115] Thermal stability: PVDF has a high thermal decomposition temperature and can remain stable at relatively high temperatures, reducing the risk of chemical corrosion.

[0116] Polyethersulfone (PES):

[0117] Excellent thermoplasticity: PES has good thermoplasticity and mechanical properties, can operate at higher temperatures, and is not easy to decompose.

[0118] Corrosion resistance: PES itself has relatively strong resistance to a variety of acids, alkalis and organic solvents, and is suitable for treating wastewater containing corrosive components.

[0119] In the process of membrane preparation, functional additives such as antioxidants, anti-thermal decomposition agents and anti-corrosion agents are added:

[0120] Antioxidant: Ensure that the polymer does not accelerate decomposition due to oxidation under high temperature conditions, thereby reducing the corrosive products produced during the decomposition process.

[0121] Anti-thermal decomposition agent: It can improve the heat resistance of the membrane when it is subjected to high temperature conditions, reduce the generation of decomposition products and control the corrosiveness of the products.

[0122] By heat treating the membrane at 150-200°C, the following effects are achieved:

[0123] Promote cross-linking reaction: Heat treatment promotes cross-linking between polymers, thereby improving the structural stability of the membrane. In the network structure of the membrane material, the higher the degree of cross-linking, the stronger its resistance to decomposition, the fewer decomposition products produced, and generally less toxic and corrosive.

[0124] Reduction of Hazardous Decomposition Products: Through effective thermal treatment, most solvents such as N,N-dimethylacetamide (DMAc) are removed, further reducing volatile organic compounds (VOCs) when the membrane decomposes.

[0125] After heat treatment, the membrane is left to cure for 24 hours. This process helps:

[0126] Improve the stability of molecular chains: Stronger molecular cross-linking structures can maintain structural integrity at high temperatures and reduce the generation of decomposition products.

[0127] Prevent re-adsorbate: Long-term standing allows any remaining solvent or additive in the membrane to evaporate, thereby reducing the release of corrosive substances caused by desorption in subsequent use.

[0128] During the use of the membrane, the selected materials and added functional additives enable the membrane to maintain chemical stability in a variety of use environments. Even under high temperature and high humidity conditions, its corrosive decomposition products are effectively reduced:

[0129] Control the production process: Ultrasonic degassing and precise temperature and humidity control can help optimize the uniformity and cohesion of the film, reduce defects and improve chemical corrosion resistance.

[0130] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A MBR membrane sewage treatment membrane, characterized in that: The treatment film is composed of the following components in weight ratio: The antioxidant is phenolic; the anti-thermal decomposition agent is hindered amine; and the anti-corrosion agent is nitrate.

2. A method for preparing an MBR membrane for wastewater treatment, characterized in that: The preparation method is used to prepare the treatment film according to claim 1, and the preparation method comprises the following steps: Step 1, dissolving and mixing: select N,N-dimethylacetamide DMAc, preheat it to 60-80°C in a stirrer, gradually add polyvinylidene fluoride PVDF and polyether sulfone PES into the preheated solvent in the required proportion, and continue stirring to form a uniform polymer solution; Step 2: Adding functional additives: After the polymer is completely dissolved, antioxidant, anti-thermal decomposition agent, anti-corrosion agent, low volatility plasticizer and lubricant are added in sequence; Step 3: Degassing: while stirring, remove bubbles in the mixture by vacuum or ultrasonic treatment; Step 4: Film forming: pour the degassed polymer solution into a pre-prepared mold to form the basic form of the film. By controlling the ambient temperature and humidity, the solvent in the mixed solution gradually evaporates from the film, resulting in film formation. Step 5, heat treatment: heat treatment of the formed film to further promote the cross-linking of the polymer and improve the film's resistance to thermal decomposition, the temperature is maintained at 150-200°C for 30 minutes to 1 hour; Step 6: Cooling and curing: Slowly cool the heat-treated film to room temperature and cure it in a static environment for 24 hours to ensure that the film material is completely stable.

3. The method for preparing a MBR membrane for sewage treatment according to claim 2, characterized in that: The weight ratio of the N,N-dimethylacetamide is 3-7 times that of polyvinylidene fluoride.

4. The method for preparing a MBR membrane for sewage treatment according to claim 3, characterized in that: The detailed steps of step 1 are: S1.

1. Material preparation: polyvinylidene fluoride PVDF; polyether sulfone PES; N,N-dimethylacetamide; S1.2, heating the solvent: add the required amount of N,N-dimethylacetamide into the container of the stirrer, turn on the heating stirrer, heat N,N-dimethylacetamide to 60-80°C, and monitor with a thermometer; S1.3, gradually add polymer: slowly add 57 g of PVDF into the heated N,N-dimethylacetamide solvent, and continue stirring for 10-20 minutes to ensure that PVDF is completely dissolved; S1.4, continue to add polyethersulfone PES: Next, gradually add 22 grams of polyethersulfone PES to the dissolved PVDF, and continue stirring for 10-20 minutes to ensure uniform mixing; S1.5, dissolution complete: At this temperature, the polymer is completely dissolved. If undissolved polymer is found, extend the stirring time by 10%; S1.

6. Maintain liquid state: After dissolution is completed, keep the solution warm to prevent the temperature from dropping and causing the polymer to precipitate again. Continue stirring at a low speed of 50-100 rpm to ensure uniformity.

5. The method for preparing a MBR membrane for sewage treatment according to claim 4, characterized in that: The detailed steps in step 2 are: S2.1, antioxidant: slowly add the antioxidant into the polymer solution, stirring for 5-10 minutes; S2.2, anti-thermal decomposition agent: Then, add 4 grams of anti-thermal decomposition agent and continue stirring for 5-10 minutes; S2.3, anti-corrosion agent: then add 3 grams of anti-corrosion agent; S2.4, low volatility plasticizer: add 2 g of low volatility plasticizer and stir for 5-10 minutes; S2.5, Lubricant: Finally, add 1 gram of lubricant and keep stirring until all ingredients are evenly mixed; S2.

6. After all additives have been added, continue stirring the solution for about 10 minutes.

6. The method for preparing a MBR membrane for sewage treatment according to claim 5, characterized in that: The detailed steps in step 4 are: S3.1, casting polymer solution: pour the degassed polymer solution evenly into the prepared mold to form a uniform film layer with a thickness of 30-200 microns; S3.2, Volatilization and film formation: Place the mold in a controlled environment: temperature: 20-30℃, humidity: 30%-50%; S3.

3. Control the volatilization rate: Continuously monitor the ambient temperature and humidity. The DMAc in the polymer solution will gradually evaporate and the film will be formed in 24-72 hours.

7. The method for preparing a MBR membrane for sewage treatment according to claim 6, characterized in that: The detailed steps of step five are: S5.

1. Preheating equipment: Before starting the heat treatment, preheat the oven to 150-200°C as an intermediate value for the experiment. The preheating time is 15-30 minutes until the equipment stabilizes at the preset temperature. S5.

2. Film placement: Carefully place the dried film on a flat tray in the oven, ensuring that the film does not overlap during heating and that there is adequate air circulation in the oven to promote uniform heating; S5.3, heat treatment time: keep the film in the oven for 30 minutes to 1 hour; S5.

4. Monitoring process: During the heat treatment process, ensure that the temperature of the oven is regularly monitored to prevent overheating or temperature fluctuations. Check every 10-15 minutes. S5.

5. Heat treatment is completed: After the heat treatment time is up, turn off the oven and let the film cool naturally to room temperature in the oven.

8. The method for preparing a MBR membrane for sewage treatment according to claim 7, characterized in that: The total mass calculation formula of the polymer in step 1 is: M total =M PVDF +M PES Where: M total is the total mass of the polymer; M PVDF is the mass of polyvinylidene fluoride; M PES It is the quality of polyethersulfone.

9. The method for preparing a MBR membrane for sewage treatment according to claim 8, characterized in that: The ratio of each polymer in step 1 is calculated as: Where: C PVDF is the mass proportion of polyvinylidene fluoride in the mixture; C PES is the mass proportion of polyethersulfone in the mixture.

10. The method for preparing a MBR membrane for sewage treatment according to claim 9, characterized in that: The amount of each additive added in step 2 is calculated as: M additive =M solution ×C additive Where: M solution is the total mass of the polymer solution; M additive is the quality of the additive; C additive is the mass ratio of the additive.

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