Ammonia-nitrogen-adsorbing MABR membrane material, and preparation method therefor and use thereof

Abstract

An ammonia-nitrogen-adsorbing MABR membrane material. The material comprises a porous support layer and a membrane layer, which is located on a surface of the porous support layer and has an ammonia-nitrogen adsorption function, wherein the membrane layer contains a functional group, which functional group is one or more of hydroxyl, amino or epoxy groups.

Description

Ammonia nitrogen adsorption type MABR membrane material, its preparation method and application

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510020359.3, filed on January 7, 2025, entitled "An Ammonia Nitrogen Adsorption Type MABR Membrane Material and Its Preparation Method and Application", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of breathable membrane material technology, specifically to an ammonia nitrogen adsorption type MABR membrane material, its preparation method, and its application. Background Technology

[0004] A membrane aerated biofilm reactor (MABR) is a novel wastewater treatment technology that combines gas membrane technology with biofilm technology. This technology uses an oxygen-permeable membrane as a carrier for microorganisms, and oxygen is bubble-free transported to the biofilm on its surface. Oxygen and pollutants diffuse into the biofilm from both sides and are gradually consumed. In this system, the microbial biofilm adheres to the surface of the oxygen-permeable hollow fiber MABR membrane. As wastewater flows around the membrane, pollutants enter the biofilm under the influence of concentration gradients and microbial adsorption. Within the biofilm, through the metabolism and proliferation of microorganisms, pollutants are converted into inorganic substances or fixed within the microorganisms, thereby purifying the water. MABR has significant technological advantages and broad application prospects in enhanced carbon and nitrogen removal. As a wastewater treatment technology with lower energy consumption and higher efficiency, MABR has been widely applied in various fields such as river management, pharmaceutical wastewater treatment, and municipal wastewater treatment.

[0005] The most crucial process in wastewater treatment is nitrification, which is divided into two stages: ammonia oxidation and nitrite oxidation. These two stages are independently completed by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), respectively. The unique advantage of MABR lies in its ability to achieve autotrophic, heterotrophic, and autotrophic-heterotrophic mixed denitrification during wastewater nitrification, specifically in the following forms:

[0006] (1) Due to its unique aerobic-anoxic biofilm layered structure, autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria can be coupled at different layers of the biofilm to achieve simultaneous nitrification and denitrification (SND). The MABR module is placed in the anoxic zone. Because the inner side of the MABR biofilm has both low organic matter and high oxygen concentration, it is conducive to the growth of aerobic nitrifying bacteria, converting ammonia nitrogen in the liquid phase into nitrate nitrogen. When the main liquid phase is in anoxic state, the outer side of the biofilm has both high organic matter and low oxygen concentration, which is conducive to the growth of heterotrophic denitrifying bacteria, realizing the denitrification process of nitrate nitrogen. The entire anoxic zone achieves simultaneous nitrification and denitrification. The advantages of the nitrification system are concentrated on the membrane surface, nitrifying the wastewater. On the outside of the membrane, some denitrification zones are formed, denitrifying nitrate into nitrogen gas. Therefore, the aeration membrane of MABR technology is also called a simultaneous nitrification and denitrification biofilm.

[0007] (2) By controlling the oxygen supply of the MABR, the nitrification process can be controlled at the nitrite stage, that is, under the action of AOB, ammonia nitrogen NH3-N is oxidized to nitrite nitrogen NO2-N, and short-cut nitrification and denitrification can be achieved in the MABR.

[0008] (3) With the discovery of anammox, short-cut nitrification-anammox (PN-A) has become a more energy-efficient nitrogen removal pathway. Under the action of anammox bacteria (AnAOB), the nitrite nitrogen NO2-N produced by short-cut nitrification can act as an electron acceptor, reacting directly with ammonia nitrogen to complete nitrogen removal. MABR, with its biofilm stratification and precise oxygen supply control, enables nitrite and anammox to be achieved in the same reactor.

[0009] The differences between the above-mentioned denitrification methods lie in the removal pathway of ammonia nitrogen in wastewater. In simultaneous nitrification-denitrification, ammonia nitrogen is converted to nitrate nitrogen in two stages, and then converted to nitrogen gas by denitrifying bacteria. In short-cut nitrification-denitrification, ammonia nitrogen is oxidized to nitrite nitrogen, and then denitrified to nitrogen gas. In short-cut nitrification-anaerobic ammonium oxidation, part of the ammonia nitrogen is oxidized to nitrite nitrogen by anaerobic ammonium oxidizing bacteria (AOB), and the other part reacts directly with nitrite nitrogen to generate N2 under the action of anaerobic ammonium oxidizing bacteria (AnAOB). Regardless of the pathway used for denitrification, the key lies in the reaction of ammonia nitrogen on the surface of the MABR membrane in the anoxic zone. In this process, it is necessary to enhance the contact process between ammonia nitrogen and the MABR membrane surface to improve the utilization efficiency of the MABR and the conversion efficiency of ammonia nitrogen. However, in existing wastewater treatment systems, due to unreasonable tank structure and uneven mixing, severe short-circuiting and dead zones often occur, preventing the MABR membrane from fully utilizing its performance and resulting in poor ammonia nitrogen treatment. Summary of the Invention

[0010] Based on this, this application provides an ammonia nitrogen adsorption type MABR membrane material, which can simultaneously improve the physical adsorption capacity for ammonia nitrogen and enhance the oxidation process of ammonia nitrogen by the biofilm on the membrane surface, effectively improving the treatment effect of ammonia nitrogen.

[0011] The method for preparing ammonia nitrogen adsorption type MABR membrane material provided in this application uses irradiation crosslinking to react monomers containing functional groups with the membrane material, thereby introducing functional groups into the membrane layer. This not only improves the mechanical properties, heat resistance, and chemical resistance of the original polymer membrane, but also enhances the compatibility between the functional groups and the membrane material, ensuring the fixation effect and functional stability of the groups. Moreover, the method is simple and requires minimal reagents.

[0012] The membrane aeration biofilm reactor provided in this application has high nitrification efficiency.

[0013] This application provides an ammonia nitrogen adsorption type MABR membrane material, including a porous support layer and a membrane layer located on the surface of the porous support layer and having ammonia nitrogen adsorption function. The membrane layer contains functional groups, which are one or more of hydroxyl, amino, or epoxy groups.

[0014] The ammonia nitrogen adsorption type MABR membrane material described above is made of polyvinylidene fluoride, polyethylene, polytetrafluoroethylene, or polypropylene.

[0015] The ammonia nitrogen adsorption type MABR membrane material described above has a root mean square surface roughness of 80-130 nm, a pore size of 0.2-0.5 μm, and a surface contact angle with water of 65-85°.

[0016] This application provides a method for preparing the above-mentioned ammonia nitrogen adsorption type MABR membrane material, comprising the following steps: irradiating an organic solvent mixture containing membrane material and functional group monomers, and coating it onto a porous support layer to form the ammonia nitrogen adsorption type MABR membrane material; wherein, during the irradiation treatment, the ambient atmosphere is maintained as a vacuum or inert gas environment, the radiation source is selected from one of β rays, γ rays, and electron beams, the irradiation dose is 40-120 kGy, the irradiation temperature is 0-15℃, and the irradiation time is 60-90 min.

[0017] The preparation method described above further includes an auxiliary agent in the mixture, which is selected from one or more of polyethylene glycol and polyvinylpyrrolidone.

[0018] According to the preparation method described above, the organic solvent mixture containing membrane material and functional group monomer is prepared by mixing solution A, which has a mass fraction of 10-50% of membrane material, and solution B, which has a mass fraction of 10-30% of functional group monomer, wherein the volume ratio of solution A to solution B is (1-3):1.

[0019] The functional monomers described above are selected from polyvinyl alcohol, hydroxyethyl methacrylate, hydroxyethyl acrylate, or 2-hydroxyethyl ether cellulose containing hydroxyl groups.

[0020] In the preparation method described above, the functional group monomer is selected from polyamide, ethyleneamine, acrylamine, acrylamide, or acrylonitrile containing an amine group.

[0021] The functional monomers described above are selected from ethylene oxide, propylene oxide, propylene oxide ether, or styrene oxide containing epoxy groups.

[0022] This application provides a membrane aeration biofilm reactor, comprising the above-mentioned ammonia nitrogen adsorption type MABR membrane material or the ammonia nitrogen adsorption type MABR membrane material prepared by the above preparation method.

[0023] This application introduces a membrane layer containing specific functional groups onto a MABR base membrane (i.e., a porous support layer) with a porous support structure. These functional groups serve a dual purpose: firstly, they interact with ammonia nitrogen through van der Waals forces, electrostatic interactions, and hydrogen bonds, achieving physical adsorption of ammonia nitrogen and promoting its proximity to the MABR membrane surface. This effectively adsorbs ammonia nitrogen near the membrane surface, facilitating subsequent treatment. Secondly, they enhance the biocompatibility of the membrane surface, promoting microbial attachment and growth, thereby strengthening the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through these synergistic effects, the treatment efficiency of ammonia nitrogen is effectively improved.

[0024] This application utilizes an irradiation crosslinking method to react monomers containing functional groups with membrane materials, thereby introducing functional groups. The preparation method is simple, and the functional groups undergo crosslinking addition reactions with the free radicals of the membrane material to form new chemical bonds, resulting in a three-dimensional crosslinked network structure with functional groups. On the one hand, this improves the mechanical properties, heat resistance, and chemical resistance of the original polymer membrane, and provides strong mechanical strength (tensile strength can reach 13-16N). On the other hand, it enhances the compatibility between the functional groups and the membrane material, ensuring the fixation effect and functional stability of the groups, and guaranteeing that the long-term operation function of the MABR membrane will not be affected. Attached Figure Description

[0025] Figure 1 shows an example of sampling for ammonia nitrogen adsorption tests using different membrane materials;

[0026] Figure 2 shows the ammonia nitrogen adsorption test results of different membrane materials;

[0027] Figure 3 is a scanning electron microscope image of microbial biofilm formation in Example 3;

[0028] Figure 4 is a scanning electron microscope image of microbial biofilm formation in Example 4. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] In existing technologies, to accelerate the ammonia oxidation process on the surface of the MABR membrane in the anoxic zone, improvements are typically made using the following methods: (1) Adjusting hydraulic conditions: By adjusting the flow rate or changing the hydraulic structure, the residence time of wastewater in the anoxic zone is extended, increasing the contact time between ammonia nitrogen and the membrane surface, thus promoting the ammonia oxidation process; (2) Increasing the tank volume and extending the residence time, allowing ammonia nitrogen to fully contact the MABR, thus promoting the ammonia oxidation process; (3) Increasing the air supply to the MABR membrane module to enhance the ammonia oxidation efficiency. Among the above methods, adjusting hydraulic conditions and increasing the air supply to the MABR membrane module usually increase energy consumption and tank volume, thereby increasing costs.

[0031] Based on this, this application introduces a membrane layer containing hydroxyl and / or amino and / or epoxy groups onto a MABR base membrane (i.e., a porous support layer) with a porous support structure. These functional groups can, on the one hand, interact with ammonia nitrogen through van der Waals forces, electrostatic interactions, and hydrogen bonds, achieving physical adsorption of ammonia nitrogen and promoting its approach to the MABR membrane surface. This effectively adsorbs ammonia nitrogen near the membrane surface, providing convenient conditions for subsequent treatment. On the other hand, it can improve the biocompatibility of the membrane surface, promoting the attachment and growth of microorganisms, thereby enhancing the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through these synergistic effects, the treatment effect of ammonia nitrogen can be effectively improved.

[0032] The van der Waals adsorption mentioned above refers to the van der Waals interaction between the functional group and the ammonia nitrogen molecule. Furthermore, the van der Waals force is an attractive force caused by intermolecular-induced dipole-dipole interaction. When the ammonia nitrogen molecule approaches the aforementioned functional group, this interaction between them leads to physical adsorption.

[0033] The electrostatic adsorption mentioned above refers to the attraction between the electrostatic interaction between the functional groups, which carry partial charges, and ammonia nitrogen molecules, thus promoting physical adsorption.

[0034] The hydrogen bond adsorption mentioned above refers to the hydrogen atoms in the aforementioned functional groups forming hydrogen bonds with hydrogen atoms or lone pairs of electrons in ammonia nitrogen, thereby promoting the adsorption process.

[0035] Specifically, this application provides an ammonia nitrogen adsorption type MABR membrane material, which includes a porous support layer and a membrane layer located on the surface of the porous support layer and having ammonia nitrogen adsorption function. The membrane layer contains functional groups, which are one or more of hydroxyl, amino, or epoxy groups.

[0036] By introducing a membrane layer containing hydroxyl, amino, or epoxy groups onto the surface of a MABR base membrane (i.e., a porous support layer) with a porous support structure, these groups can interact with ammonia nitrogen through van der Waals forces, electrostatic interactions, and hydrogen bonds, achieving physical adsorption of ammonia nitrogen and promoting its proximity to the MABR membrane surface. This effectively adsorbs ammonia nitrogen near the membrane surface, providing favorable conditions for subsequent treatment. Furthermore, it can improve the biocompatibility of the membrane surface, promoting microbial attachment and growth, thereby enhancing the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through these synergistic effects, the ammonia nitrogen treatment effect is effectively improved, with an ammonia nitrogen nitrification rate reaching 1.9 g N / m³. 2 / d or more.

[0037] It is worth noting that among the three functional groups mentioned above, the epoxy group exhibits the best adsorption effect for ammonia nitrogen. Under the same conditions, the ammonia nitrogen treatment effect is better when the functional group is an epoxy group.

[0038] In MABR membrane materials, the porous support layer (i.e., the porous support structure of the MABR base membrane) primarily serves to support and stabilize the membrane structure, while ensuring the smooth transfer and reaction of oxygen and wastewater through the membrane layer. In MABR membrane technology, the porous support layer, the membrane layer containing functional groups (and the biofilm formed on it), and the aeration membrane are tightly integrated to form a highly efficient wastewater treatment system. Oxygen is transferred from the aeration membrane through the porous support layer and the membrane layer containing functional groups to the biofilm, providing the necessary oxygen for microorganisms to carry out metabolic activities and nitrification. Simultaneously, pollutants in the wastewater come into direct contact with the biofilm and react with the microorganisms, thereby achieving ammonia nitrogen removal.

[0039] The choice of porous support layer material in this application is not limited. Common porous support layer materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polydimethylsiloxane (PDMS) can be used. These materials have high durability, chemical stability, and mechanical strength, and can be used for a long time in complex wastewater environments.

[0040] The choice of membrane material in this application is not particularly limited; conventional biomembrane materials in the art can be used. For example, in some specific embodiments, the membrane material is polyvinylidene fluoride (PVDF), polyethylene (PE), polytetrafluoroethylene (PTFE), or polypropylene (PP).

[0041] Studies have shown that when the root mean square roughness of the membrane surface is 80-130 nm, the pore size is 0.2-0.5 μm, and the contact angle with water is 65-85°, the MABR membrane material has better adsorption performance for ammonia nitrogen and higher ammonia nitrogen oxidation efficiency.

[0042] This application also provides a method for preparing the above-mentioned ammonia nitrogen adsorption type MABR membrane material, including the following steps: irradiating an organic solvent mixture containing membrane material and functional group monomers, and coating it onto a porous support layer to form the ammonia nitrogen adsorption type MABR membrane material; wherein, during the irradiation treatment, the ambient atmosphere is maintained as a vacuum or inert gas environment, the radiation source is selected from one of β rays, γ rays, and electron beams, the irradiation dose is 40-120 kGy, the irradiation temperature is 0-15℃, and the irradiation time is 60-90 min.

[0043] In the above method, the organic solvent can be selected according to conventional methods in the field. For example, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and methyl tert-butyl ether are commonly used because these organic solvents usually have good solubility and volatility, which is beneficial to the dissolution of membrane materials.

[0044] It is worth noting that the organic solvent mixture during irradiation treatment does not contain water. This is because water affects the solubility of the membrane material in the solvent. In addition, water residue in the membrane may also affect the membrane's permeability and mechanical properties, reduce the processing efficiency of the MABR system, and make the membrane prone to detachment from the porous support layer.

[0045] Irradiation treatment eliminates the influence of impurities on the reaction process by controlling the atmosphere of the irradiation environment. Specifically, it can be carried out under vacuum conditions to eliminate gas interference with the irradiation reaction, or it can be carried out in an inert gas environment, which can be one of nitrogen, helium, or argon.

[0046] Furthermore, to improve the performance of the membrane, the irradiation treatment mixture also contains additives. For example, in some specific embodiments, polyethylene glycol and / or polyvinylpyrrolidone are added to improve the flexibility and extensibility of the membrane.

[0047] In some specific embodiments, the organic solvent mixture containing the membrane material and the functional group monomer is prepared by mixing solution A, which contains 10-50% by mass of the membrane material, and solution B, which contains 10-30% by mass of the functional group monomer, wherein the volume ratio of solution A to solution B is (1-3):1. By preparing the solutions separately and then mixing them, it can be ensured that both the membrane material and the functional group monomer are fully dissolved and uniformly mixed.

[0048] The aforementioned functional monomers are selected from hydroxyl-containing monomers and / or amino-containing monomers and / or epoxy-containing monomers. Specifically, hydroxyl-containing monomers may be selected from polyvinyl alcohol, hydroxyethyl methacrylate, hydroxyethyl acrylate, and 2-hydroxyethyl ether cellulose; amino-containing monomers may be selected from polyamide, vinylamine, acrylamine, acrylamide, and acrylonitrile; and epoxy-containing monomers may be selected from ethylene oxide, propylene oxide, epoxy propylene ether, and epoxy styrene.

[0049] The detailed principle and steps of introducing functional groups using irradiation treatment in this application are as follows:

[0050] (1) Irradiation treatment to generate free radicals: The membrane material and monomers containing hydroxyl, amino, or epoxy groups are mixed and then exposed to a suitable radiation source for irradiation treatment. Ionizing radiation acts on the irradiated membrane material, generating ionization and exciting the release of orbital electrons. Atoms or molecules in the membrane material break down, generating free radicals. A detailed explanation is provided below, using polyethylene, polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride as examples of membrane materials:

[0051] When polyethylene (PE) is irradiated, high-energy particles (such as β and γ rays, electron beams, etc.) act on the polyethylene molecular chain, producing two methyl free radicals CH2·.

[0052] Under irradiation conditions, one carbon-carbon double bond in a polypropylene (PP) molecule breaks, forming a methyl radical (CH3·) and a vinyl radical (CH2=CH2)·.

[0053] Under irradiation conditions, high-energy rays (such as β, γ rays, and electron beams) have extremely strong penetrability, which can cause the C-F bonds on the surface of PTFE material to break and generate free radicals, thereby initiating the surface grafting polymerization of monomers to form two fluorine free radicals (CF2·).

[0054] Under irradiation conditions, the carbon-fluorine bonds in polyvinylidene fluoride (PVDF) molecules break, forming a fluorine radical (CF2·) and a hydrogen radical (CHF·).

[0055] (2) Introduction of functional groups and cross-linking reaction: Under the induction of high-energy rays, the membrane material generates free radicals. The functional groups in the monomer undergo cross-linking addition reactions with the free radicals to form new chemical bonds, forming a three-dimensional cross-linked network structure with functional groups, which improves the mechanical properties, heat resistance, and chemical resistance of the original polymer membrane material. The free radical R· undergoes a cross-linking addition reaction with the functional group (hydroxyl-OH, amino-NH2, or epoxy-O-) to form a new compound R-OH, R-NH2, or RO-, as detailed below:

[0056] R·+-OH→R-OH;

[0057] R·+-NH2→R-NH2;

[0058] 2R·+-O-→ROR.

[0059] The method of introducing functional groups using the above-mentioned irradiation is simple to operate. The functional groups undergo cross-linking addition reactions with the free radicals of the membrane material, forming new chemical bonds and resulting in a three-dimensional cross-linked network structure with functional groups. This improves the mechanical properties, heat resistance, and chemical resistance (tensile strength 13–16 N) of the original polymer membrane, and enhances the compatibility between the functional groups and the membrane material (surface water contact angle 75°–90°, good hydrophilicity). This ensures the fixation effect and functional stability of the functional groups, guaranteeing that the long-term operation of the MABR membrane will not be affected. Furthermore, when the functional group is an epoxy group and introduced using irradiation, the ammonia nitrification rate can reach 3.75 g N / m³. 2 / d or more.

[0060] The MABR membranes prepared by the above method have a root mean square roughness of 80-130 nm, a pore size of 0.2-0.5 μm, a surface contact angle of 65°-85°, are micro-hydrophilic materials, and have an oxygen transfer rate of 16.53-33.26 g O2 / (m 2 ·d), the nitrification rate can reach 1.9 g N / (m 2 ·d) and above.

[0061] This application also provides a membrane aeration biofilm reactor, which includes the above-mentioned ammonia nitrogen adsorption type MABR membrane material or the ammonia nitrogen adsorption type MABR membrane material prepared by the above-mentioned preparation method. This reactor has a high ammonia nitrogen oxidation efficiency.

[0062] The ammonia nitrogen adsorption type MABR membrane material described in this application will be described in detail below with reference to specific embodiments.

[0063] Example 1

[0064] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polyethylene) and an outer layer material with functional groups having ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0065] Step 1, Preparation of Solution A: Solute polyethylene (PE) and additive polyvinylpyrrolidone are dissolved in solvent dimethylformamide to form solution A. Specifically, the mixture is heated in a water bath at 33°C and stirred for 18 minutes to ensure complete dissolution of the solute in the solvent. The total mass fraction of solution A is 28% for the solute and 16% for the additive. The additive's role is to improve the flexibility and extensibility of the membrane.

[0066] Step 2, Preparation of Solution B: Hydroxyethyl methacrylate, a monomer containing a hydroxyl group, is dissolved in dimethylacetamide to form Solution B. Specifically, the solution is heated in a water bath at 36°C and magnetically stirred for 15 minutes to ensure complete dissolution. The mass fraction of the functional group monomer is 20%.

[0067] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 25 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0068] Step 4: Irradiation treatment under vacuum conditions to form a MABR membrane material with ammonia nitrogen adsorption function: the radiation source is beta rays, the radiation dose is 60 kGy, the radiation temperature is 12℃, and the radiation time is 60 min. After radiation treatment, it is left to stand at room temperature for 2 hours for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming a MABR membrane material with ammonia nitrogen adsorption function.

[0069] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0070] Example 2

[0071] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polypropylene) and an outer layer material with functional groups having ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0072] Step 1, Preparation of Solution A: Solute polypropylene (PP) and additive polyethylene glycol are dissolved in solvent methyl tert-butyl ether to form solution A. Specifically, the solution is heated in a water bath at 55°C and stirred for 30 minutes to ensure complete dissolution of the solute in the solvent. The total mass fraction of solution A is 40% solute and 15% additive. The additive's role is to improve the flexibility and extensibility of the membrane.

[0073] Step 2, Preparation of Solution B: Allylamine, a monomer containing an amine functional group, is dissolved in dimethyl sulfoxide to form solution B. Specifically, the solution is heated in a water bath at 45°C and magnetically stirred for 20 minutes to ensure complete dissolution. The mass fraction of the functional group monomer is 20%.

[0074] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 30 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0075] Step 4: Irradiation treatment under vacuum conditions to prepare MABR membrane material with ammonia nitrogen adsorption function: the radiation source is gamma rays, the radiation dose is 80 kGy, the radiation temperature is 10℃, and the radiation time is 75 min. After radiation treatment, the membrane is allowed to stand at room temperature for 2.5 h for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming a MABR membrane material with ammonia nitrogen adsorption function.

[0076] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0077] Example 3

[0078] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polytetrafluoroethylene) and an outer layer material with functional groups having ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0079] Step 1, Preparation of Solution A: The solute (polytetrafluoroethylene membrane, PTFE) and the additive (polyvinylpyrrolidone) are dissolved in the solvent (methyl tert-butyl ether) to form Solution A. Specifically, the solution is heated in a water bath at 35°C and stirred for 12 minutes to ensure complete dissolution of the solute in the solvent. The total mass fraction of Solution A is 21% for the solute and 16% for the additive. The additive's role is to improve the membrane's flexibility and extensibility.

[0080] Step 2, Preparation of Solution B: Ethylene oxide, a monomer containing an epoxy group, is dissolved in methyl tert-butyl ether to form solution B. Specifically, the solution is heated in a water bath at 38°C and magnetically stirred for 30 minutes to ensure complete dissolution. The mass fraction of the functional group monomer is 25%.

[0081] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 28 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0082] Step 4: Irradiation treatment under vacuum conditions to prepare MABR membrane material with ammonia nitrogen adsorption function: the radiation source is an electron beam, the radiation dose is 100 kGy, the radiation temperature is 15℃, and the radiation time is 90 min. After radiation treatment, it is left to stand at room temperature for 3 h for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming a MABR membrane material with ammonia nitrogen adsorption function.

[0083] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0084] Example 4

[0085] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polyvinylidene fluoride) and an outer layer material with functional groups having ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0086] Step 1, Preparation of Solution A: Dissolve the solute polyvinylidene fluoride (PVDF) and the auxiliary agent polyvinylpyrrolidone in the solvent methyl tert-butyl ether to form solution A. Specifically, heat in a water bath at 45°C and stir for 15 minutes to ensure the solute is completely dissolved in the solvent.

[0087] In this solution, the solute mass fraction is 40% and the additive mass fraction is 20%, based on the total mass of solution A. The additive's function is to improve the membrane's flexibility and extensibility.

[0088] Step 2, Preparation of Solution B: Epoxy styrene, a monomer containing an epoxy group, is dissolved in dimethylacetamide to form solution B. Specifically, the solution is heated in a water bath at 55°C and magnetically stirred for 30 minutes to ensure complete dissolution. The mass fraction of the functional group monomer is 18%.

[0089] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 25 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0090] Step 4: Irradiation treatment under vacuum conditions to prepare MABR membrane material with ammonia nitrogen adsorption function: the radiation source is gamma rays, the radiation dose is 80 kGy, the radiation temperature is 12℃, and the radiation time is 80 min. After radiation treatment, the membrane is left to stand at room temperature for 3 hours for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming a MABR membrane material with ammonia nitrogen adsorption function.

[0091] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0092] Example 5

[0093] A type of ammonia nitrogen adsorption MABR membrane material is composed of a porous support layer (polytetrafluoroethylene) and an outer layer material coated on the surface of the porous support layer. Its main difference from Example 3 is that the epoxy-functionalized monomers are introduced through a mixing process without irradiation treatment. The specific preparation method is as follows:

[0094] Step 1, Preparation of Solution A: The solute polytetrafluoroethylene membrane (PTFE) and the auxiliary agent polyvinylpyrrolidone are dissolved in the solvent methyl tert-butyl ether to form solution A. Specifically, the solution is heated in a water bath at 35°C and stirred for 12 minutes to ensure that the solute is completely dissolved in the solvent.

[0095] Of these, based on the total mass of solution A, the solute mass fraction is 21%, and the additive mass fraction is 16%. The role of the additive is to improve the flexibility and extensibility of the membrane.

[0096] Step 2, Preparation of Solution B: Ethylene oxide, a monomer containing an epoxy group, is dissolved in methyl tert-butyl ether to form solution B. Specifically, the solution is heated in a water bath at 38°C and magnetically stirred for 30 minutes to ensure complete dissolution. The mass fraction of the functional group monomer is 25%.

[0097] Step 3, Mixing and stirring: Mix 100 mL of solution A with 80 mL of solution B using magnetic stirring for 28 min to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A, forming solution C, which will be used as the casting solution.

[0098] Step 4, membrane fiber preparation: The casting solution is injected into a spinning device containing an inner tube. An appropriate core solution (which can be one of pure water, methanol, ethanol, or isopropanol) is injected into the inner tube, which has a diameter of 0.75 mm. The casting solution is extruded vertically downwards from the spinneret, and after passing through a certain air distance, it enters a coagulation bath (pure water). In the coagulation bath, transient phase separation occurs, and the membrane fibers are formed. The spinning device should be preheated for at least 2 hours before operation. The spinning temperature is 100℃. Air is used between the spinneret and the coagulation bath, with a vertical spacing of 1.45 m. The spinneret extrusion speed is controlled at 0.45 cm / s, and the coagulation bath temperature is 38℃.

[0099] Step 6, Post-processing: Place the obtained membrane fibers in a drying oven to dry at a temperature of 65°C for 32 hours.

[0100] Comparative Example 1

[0101] A MABR membrane material comprises a porous support layer (polyvinylidene fluoride) and an outer layer material coated on the surface of the porous support layer. The specific preparation method is as follows:

[0102] Step 1, Preparation of Solution A: Solute polyethylene (PE) and additive polyvinylpyrrolidone are dissolved in solvent dimethylformamide to form solution A. Specifically, the solution is heated in a water bath at 33°C and stirred for 18 minutes to ensure complete dissolution of the solute in the solvent.

[0103] Of these, based on the total mass of solution A, the solute mass fraction is 28%, and the additive mass fraction is 16%. The role of the additive is to improve the flexibility and extensibility of the membrane.

[0104] Step 2, Preparation of Solution B: Acetic acid, a monomer containing a carboxyl functional group, is dissolved in dimethylacetamide to form solution B. Specifically, the solution is heated in a water bath at 36°C and magnetically stirred for 15 minutes to ensure complete dissolution. The mass fraction of the functional monomer is 20%.

[0105] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 25 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0106] Step 4: Irradiation treatment under vacuum conditions to prepare MABR membrane material: The radiation source is beta rays, the radiation dose is 60 kGy, the radiation temperature is 12℃, and the radiation time is 60 min. After radiation treatment, the membrane is left to stand at room temperature for 2 h for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming the MABR membrane material.

[0107] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0108] Comparative Example 2

[0109] A MABR membrane material comprises a porous support layer (polypropylene) and an outer layer material coated on the surface of the porous support layer. The specific preparation method is as follows:

[0110] Step 1, Preparation of Solution A: Dissolve the solute polypropylene (PP) and the additive (polyethylene glycol) in the solvent methyl tert-butyl ether to form solution A. Specifically, heat in a water bath at 55°C and stir for 30 minutes to ensure the solute is completely dissolved in the solvent.

[0111] Of which, based on the total mass of solution A, the solute mass fraction is 40% and the auxiliary agent mass fraction is 15%.

[0112] Step 2, Preparation of Solution B: Acetone, containing a carbonyl functional group, is dissolved in dimethyl sulfoxide to form solution B. Specifically, the solution is heated in a water bath at 45°C and magnetically stirred for 20 minutes to ensure complete dissolution. The mass fraction of the functional group monomer is 20%.

[0113] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 30 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0114] Step 4: Irradiation treatment under vacuum conditions to prepare MABR membrane material: The radiation source is gamma rays, the radiation dose is 80 kGy, the radiation temperature is 10℃, and the radiation time is 75 min. After radiation treatment, the membrane is left to stand at room temperature for 2.5 h for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming the MABR membrane material.

[0115] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0116] Comparative Example 3

[0117] A MABR membrane material comprises a porous support layer (polypropylene) and an outer layer material coated on the surface of the porous support layer. The specific preparation method is as follows:

[0118] Step 1, Preparation of Solution A: Dissolve the solute polypropylene (PP) and the auxiliary agent polyethylene glycol in the solvent methyl tert-butyl ether to form solution A. Specifically, heat in a water bath at 55°C and stir for 30 minutes to ensure the solute is completely dissolved in the solvent.

[0119] In this solution, the solute mass fraction is 40% and the additive mass fraction is 15% based on the total mass of solution A. The additive's function is to improve the membrane's flexibility and extensibility.

[0120] Step 2, Preparation of Solution B: Isopropylamine, a monomer containing an amino functional group, is dissolved in dimethyl sulfoxide to form Solution B. Specifically, the solution is heated in a water bath at 45°C and magnetically stirred for 20 minutes to ensure complete dissolution. The mass fraction of the functional monomer is 20%.

[0121] Step 3, Mixing and stirring: Mix 100mL of solution A with 80mL of solution B using a magnetic stirrer for 30 minutes to ensure that the two solutions are fully mixed and that solution B is evenly dispersed in solution A to form solution C.

[0122] Step 4: Irradiation treatment under vacuum conditions to form MABR membrane material: The radiation source is gamma rays, the radiation dose is 80 kGy, the radiation temperature is 10℃, and the radiation time is 75 min. After radiation treatment, the membrane is left to stand at room temperature for 2.5 h for degassing to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy initiates a free radical reaction in the membrane material, and then functional groups are introduced to crosslink with the free radicals of the membrane material, forming the MABR membrane material.

[0123] Step 5: Apply the obtained MABR membrane material onto the porous support layer and dry it to obtain the final product.

[0124] The above embodiments and comparative examples are summarized in detail in Table 1 below:

[0125] Table 1

[0126] (1) Adsorption experiment

[0127] An ammonium chloride solution with an ammonia nitrogen concentration of 45 mg / L was filled into an acrylic container measuring 1.2 m × 1.2 m × 1.0 m. Membrane materials prepared according to the methods of the examples and comparative examples were placed into different acrylic containers of the same size. After immersion for 15 min, ammonia nitrogen concentrations were measured at locations far from and near the membrane material. Points 1 and 4, and points 2 and 3 were axially symmetrical (see Figure 1). The test results are shown in Figure 2.

[0128] As shown in Figure 2, the ammonia nitrogen concentrations at sites 2 and 3 near the membrane material in Examples 1-5 are significantly higher than those at sites 1 and 4 far from the membrane material, and this difference is even more pronounced in Examples 3-4. In contrast, the ammonia nitrogen concentrations at sites 2 and 3 near the membrane material in the comparative examples are comparable to those at sites 1 and 4 far from the membrane material. This indicates that the membrane material provided in the examples of this application has a significant ammonia nitrogen adsorption function, while the membrane material in the comparative examples does not have the ammonia nitrogen adsorption function. Furthermore, the adsorption effect is better when the functional group is an epoxy group (Examples 3 and 4).

[0129] (2) Operational test

[0130] Sludge from the aerobic tank of a wastewater treatment plant was placed into an plexiglass container. Domestic sewage (average ammonia nitrogen concentration 45 mg / L) was pumped into the plexiglass container (influent flow rate 50 L / min), and the overflow was allowed. Different membrane materials prepared in the examples and comparative examples were used to supply air to the MABR membrane modules, and the effluent quality was analyzed. The ammonia nitrogen concentration in the effluent was measured, and the ammonia oxidation efficiency (NR) of different membrane materials was calculated. The results are shown in Table 2 below.

[0131] NHx,inf — Ammonia nitrogen concentration entering the plexiglass reactor, 45 mg / L;

[0132] NHx,eff — Ammonia nitrogen concentration effluent from the plexiglass reactor, mg / L;

[0133] A – MABR membrane area, 100m² 2 ;

[0134] Qinf – Flow rate through the MABR reactor unit, 72m³ 3 / d;

[0135] NR—MABR nitration rate, g N / m 2 / d.

[0136] Table 2

[0137] The results above show that the nitration rate of MABR membrane materials can be significantly increased when hydroxyl, amino, or epoxy groups are introduced into the membrane layer, with the ammonia nitration rate reaching 1.9 g N / m³. 2 / d or more; especially when the introduced group is an epoxy group, the ammonia nitrogen nitration rate is even better; and further, as can be seen from Examples 3, 4 and 5, when the functional group is introduced by irradiation, the nitration rate is improved more significantly, and the ammonia nitrogen nitration rate can reach 3.75 g N / m 2 / d or more.

[0138] Furthermore, the surface contact angle shows that the introduction of hydroxyl, amino, and epoxy groups in the examples significantly improved the water contact angle of the membrane surface, enhancing hydrophilicity. This is beneficial for the immobilization of microorganisms on the membrane surface and improves the functional stability of the nitrification process, thus ensuring that the long-term operation of the MABR membrane is not affected. The scanning electron microscope images of the membrane surface in Figures 3 and 4 also show that the good hydrophilicity results in excellent biofilm attachment.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An ammonia nitrogen adsorption type MABR membrane material, characterized in that, It includes a porous support layer and a membrane layer located on the surface of the porous support layer and having ammonia nitrogen adsorption function. The membrane layer contains functional groups, which are hydroxyl or epoxy groups. The membrane has a root mean square roughness of 80-130 nm, a pore size of 0.2-0.5 μm, and a surface contact angle with water of 65-85°.

2. The ammonia nitrogen adsorption type MABR membrane material according to claim 1, characterized in that, The membrane layer is made of polyvinylidene fluoride, polyethylene, polytetrafluoroethylene, or polypropylene.

3. The method for preparing the ammonia nitrogen adsorption type MABR membrane material according to claim 1 or 2, characterized in that, Includes the following steps: An organic solvent mixture containing membrane material and functional group monomers is irradiated and coated onto a porous support layer to form the ammonia nitrogen adsorption type MABR membrane material. During the irradiation treatment, the ambient atmosphere is maintained as a vacuum or inert gas environment, the radiation source is selected from one of beta rays, gamma rays, and electron beams, the irradiation dose is 40-120 kGy, the irradiation temperature is 0-15℃, and the irradiation time is 60-90 min.

4. The preparation method of the ammonia nitrogen adsorption type MABR membrane material according to claim 3, characterized in that, The mixture also contains an additive selected from one or more of polyethylene glycol and polyvinylpyrrolidone.

5. The method for preparing the ammonia nitrogen adsorption type MABR membrane material according to claim 3 or 4, characterized in that, The organic solvent mixture containing the membrane material and the functional group monomer is composed of solution A, which has a mass fraction of 10-50% of the membrane material, and solution B, which has a mass fraction of 10-30% of the functional group monomer, wherein the volume ratio of solution A to solution B is (1-3):

1.

6. The method for preparing the ammonia nitrogen adsorption type MABR membrane material according to claim 3 or 4, characterized in that, The functional group monomer is selected from polyvinyl alcohol containing hydroxyl groups, hydroxyethyl methacrylate, hydroxyethyl acrylate, or 2-hydroxyethyl ether cellulose; and / or The functional group monomer is selected from polyamides containing amine groups, ethyleneamine, acrylamine, acrylamide, or acrylonitrile; and / or The functional monomer is selected from ethylene oxide, propylene oxide, propylene oxide ether, or styrene oxide containing epoxy groups.

7. A membrane-aerated biofilm reactor, characterized in that, Includes the ammonia nitrogen adsorption type MABR membrane material according to claim 1 or 2, or the ammonia nitrogen adsorption type MABR membrane material prepared by the preparation method according to any one of claims 3-6.

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