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

Abstract

The present invention relates to an ammonia nitrogen adsorption type MABR membrane material and a preparation method and application thereof. The ammonia nitrogen adsorption type MABR membrane material comprises a porous support layer and a membrane layer located on the surface of the porous support layer and having an ammonia nitrogen adsorption function, wherein the membrane layer contains functional groups, and the functional groups are one or more of hydroxyl, amine or epoxy groups. The present invention introduces a membrane layer containing specific functional groups on the surface of the porous support layer. On the one hand, the functional groups in the membrane layer can interact with ammonia nitrogen through van der Waals forces, electrostatic effects and hydrogen bonds, thereby achieving physical adsorption of ammonia nitrogen and promoting ammonia nitrogen to approach the surface of the MABR membrane, thereby effectively adsorbing 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, promote the attachment and growth of microorganisms, and then enhance the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through the above-mentioned synergistic effect, the treatment effect of ammonia nitrogen is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of breathable membrane materials, and in particular to an ammonia nitrogen adsorption type MABR membrane material and a preparation method and application thereof. Background Art

[0002] Membrane aerated biofilm reactor (MABR) is a new type of sewage treatment technology that combines gas membrane technology with biofilm technology. This technology uses oxygen-permeable membrane as a microbial carrier and transmits oxygen to the biofilm on its surface without bubbles. Oxygen and pollutants diffuse into the biofilm from both sides of the biofilm and are gradually consumed. In this system, the microbial membrane is attached to the surface of the oxygen-permeable hollow fiber MABR membrane. When sewage flows around the membrane, pollutants enter the biofilm under the action of concentration gradient and microbial adsorption. In the biofilm, through the metabolism and proliferation of microorganisms, pollutants are converted into inorganic substances or fixed in the microorganisms, thereby achieving water purification. MABR has great technical advantages and broad application prospects in strengthening carbon removal and nitrogen removal. As a sewage treatment technology with lower energy consumption and higher efficiency, MABR has been widely used in many fields such as river management, medical wastewater treatment, and municipal wastewater treatment.

[0003] The most important process in sewage treatment is nitrification, which is divided into ammonia oxidation and nitrite oxidation stages. These two stages are completed independently by ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). The special advantage of MABR is that in the sewage nitrification process, autotrophic, heterotrophic and autotrophic-heterotrophic mixed denitrification can be achieved, specifically in the following forms:

[0004] (1) Because of its unique aerobic-anoxic biofilm layered structure, autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria can be coupled at different levels of the biofilm to achieve simultaneous nitrification and denitrification (SND). That is, the MABR component is placed in the anoxic zone. Since the inner side of the MABR biofilm has both low organic matter and high oxygen concentrations, it is conducive to the growth of aerobic nitrifying bacteria, which converts ammonia nitrogen in the liquid phase into nitrate nitrogen. When the main body of the liquid phase is in anoxic state, the outer side of the biofilm has both high organic matter and low oxygen concentrations, which is conducive to the growth of heterotrophic denitrifying bacteria, realizing the denitrification process of nitrate nitrogen, and achieving simultaneous nitrification and denitrification in the entire anoxic zone. The advantages of the nitrification system will gather on the membrane surface, and the sewage will undergo nitrification reaction. On the outside of the membrane, some denitrification areas will be formed, and nitrates will be denitrified into nitrogen. Therefore, the aeration membrane of MABR technology is also called a simultaneous nitrification and denitrification biofilm.

[0005] (2) By controlling the oxygen supply in the MABR, the nitrification process can be controlled at the nitrite stage, that is, under the action of AOB, ammonia nitrogen NH 3-N is oxidized to nitrite nitrogen NO 2 -N, realizing short-cut nitrification and denitrification in MABR.

[0006] (3) With the discovery of anaerobic ammonium oxidation (ANAMMOX), short-term nitrification-anaerobic ammonium oxidation (PN-A) has become a more energy-efficient denitrification pathway. Under the action of anaerobic ammonium oxidizing bacteria (AnAOB), the nitrite nitrogen NO produced by short-term nitrification is converted into 2 -N can act as an electron acceptor and react directly with ammonia nitrogen to complete denitrification. MABR, with its biofilm stratification and precise control of oxygen supply, enables nitrite and anaerobic ammonium oxidation to be achieved in the same reactor.

[0007] The above denitrification methods differ in the removal path of ammonia nitrogen in sewage. In the process of simultaneous nitrification and denitrification, ammonia nitrogen is converted into nitrate nitrogen in two stages, and then converted into nitrogen gas by denitrifying bacteria. In the process of short-range nitrification and denitrification, ammonia nitrogen is oxidized into nitrite nitrogen, and then denitrified into nitrogen gas. In the process of short-range nitrification-anaerobic ammonium oxidation, part of ammonia nitrogen is oxidized into nitrite nitrogen by AOB, and the other part of ammonia nitrogen and nitrite nitrogen react directly to generate N under the action of anaerobic ammonium oxidizing bacteria (AnAOB). 2 Regardless of the method used to achieve denitrification, the key lies in the reaction of ammonia nitrogen in the anoxic zone on the surface of the MABR membrane. In this process, the contact process between ammonia nitrogen and the surface of the MABR membrane needs to be strengthened to improve the utilization efficiency of MABR and the conversion efficiency of ammonia nitrogen. However, in existing sewage treatment systems, the system short-circuit and dead zone phenomena are serious due to unreasonable tank structure and uneven stirring, and the performance of the MABR membrane cannot be fully utilized, resulting in poor ammonia nitrogen treatment effect. Summary of the invention

[0008] Based on this, the present invention provides an ammonia nitrogen adsorption type MABR membrane material, which can simultaneously improve the physical adsorption capacity of ammonia nitrogen and strengthen the oxidation process of ammonia nitrogen by the biofilm on the membrane surface, thereby effectively improving the treatment effect of ammonia nitrogen.

[0009] The preparation method of the ammonia nitrogen adsorption type MABR membrane material provided by the present invention uses a radiation cross-linking method to make a monomer containing a functional group react with a membrane material to achieve the introduction of the functional group into the membrane layer, which not only improves the mechanical properties, heat resistance and chemical resistance of the original polymerized membrane, but also improves the compatibility of the functional group and the membrane material, ensures the fixation effect and functional stability of the group, and the method is simple and has simple requirements on reagents.

[0010] The membrane aeration biofilm reactor provided by the invention has high nitrification efficiency.

[0011] The present invention provides an ammonia nitrogen adsorption type MABR membrane material, comprising a porous support layer and a membrane layer located on the surface of the porous support layer and having an ammonia nitrogen adsorption function, wherein the membrane layer contains a functional group, and the functional group is one or more of a hydroxyl group, an amine group or an epoxy group.

[0012] According to the above-mentioned ammonia nitrogen adsorption type MABR membrane material, the material of the membrane layer is polyvinylidene fluoride, polyethylene, polytetrafluoroethylene or polypropylene.

[0013] According to the above-mentioned ammonia nitrogen adsorption type MABR membrane material, the surface root mean square roughness of the membrane layer is 80-130nm, the pore size is 0.2-0.5μm, and the surface contact angle to water is 65-85°.

[0014] The present invention provides a method for preparing the above-mentioned ammonia nitrogen adsorption type MABR membrane material, comprising the following steps: irradiating an organic solvent mixed liquid containing a membrane layer material and a functional group monomer, and coating the mixed liquid on 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 beta rays, gamma rays, and electron beams, the irradiation dose is 40-120 kGy, the irradiation temperature is 0-15°C, and the irradiation time is 60-90 min.

[0015] According to the above-mentioned preparation method, the mixed solution further contains an auxiliary agent, and the auxiliary agent is selected from one or more of polyethylene glycol and polyvinyl pyrrolidone.

[0016] According to the preparation method described above, the organic solvent mixture containing the membrane material and the functional group monomer is prepared by mixing a solution A with a membrane material mass fraction of 10-50% and a solution B with a functional group monomer mass fraction of 10-30%, wherein the volume ratio of solution A to solution B is (1-3):1.

[0017] According to the preparation method described above, the functional group monomer is selected from polyvinyl alcohol containing a hydroxyl group, hydroxyethyl methacrylate, hydroxyethyl acrylate or 2-hydroxyethyl ether cellulose.

[0018] According to the preparation method described above, the functional group monomer is selected from polyamide, vinylamine, acrylamine, acrylamide or acrylonitrile containing an amino group.

[0019] According to the preparation method described above, the functional group monomer is selected from ethylene oxide, propylene oxide, epoxypropene ether or styrene oxide containing epoxy groups.

[0020] The present invention provides a membrane aerated 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-mentioned preparation method.

[0021] The present invention introduces a membrane layer containing specific functional groups on the MABR base membrane (i.e., the porous support layer) with a porous support structure. The functional groups in the membrane layer can play a dual role: on the one hand, it can interact with ammonia nitrogen through van der Waals force, electrostatic effect, and hydrogen bond, so as to achieve physical adsorption of ammonia nitrogen and promote ammonia nitrogen to approach the surface of the MABR membrane, thereby effectively adsorbing 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, promote the attachment and growth of microorganisms, and further enhance the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through the above synergistic effect, the treatment effect of ammonia nitrogen is effectively improved.

[0022] The present invention uses radiation cross-linking method to make monomers containing functional groups react with membrane materials to achieve the introduction of functional groups. The preparation method is simple, and the functional groups undergo cross-linking addition reaction with free radicals of the membrane material to form new chemical bonds, thereby obtaining a three-dimensional cross-linked network structure with functional groups. On the one hand, the mechanical properties, heat resistance and chemical resistance of the original polymer membrane are improved, and the membrane has strong mechanical strength (tensile strength can reach 13-16N). On the other hand, the compatibility between the functional groups and the membrane materials is improved, thereby ensuring the fixing effect and functional stability of the groups, and ensuring that the long-term operation function of the MABR membrane will not be affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Examples of sampling for ammonia nitrogen adsorption tests on different membrane materials;

[0024] Figure 2 The results of ammonia nitrogen adsorption tests on different membrane materials;

[0025] Figure 3 This is a scanning electron microscope image of microbial biofilm in Example 3;

[0026] Figure 4 This is a scanning electron microscope image of the microbial biofilm in Example 4. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0028] In order to speed up the ammonia oxidation process on the surface of the MABR membrane in the anoxic zone, the prior art usually uses the following methods to improve it: (1) Adjusting hydraulic conditions: By adjusting the flow rate or changing the hydraulic structure, the sewage stays in the anoxic zone for a longer time, increasing the contact time between ammonia nitrogen and the membrane surface, and promoting the ammonia oxidation process; (2) Increasing the tank capacity, extending the residence time, allowing ammonia nitrogen to fully contact with the MABR, and promoting the ammonia oxidation process; (3) Increasing the air supply of the MABR membrane module and enhancing the ammonia oxidation efficiency. In the above methods, adjusting hydraulic conditions and increasing the air supply of the MABR membrane module usually increase energy consumption and increase the tank capacity, thereby increasing costs.

[0029] Based on this, the present invention introduces a membrane layer containing hydroxyl and / or amine and / or epoxy groups on a MABR base membrane (i.e., a porous support layer) having a porous support structure. On the one hand, the above functional groups can interact with ammonia nitrogen through van der Waals forces, electrostatic effects, and hydrogen bonds, thereby achieving physical adsorption of ammonia nitrogen and promoting ammonia nitrogen to approach the surface of the MABR membrane, thereby effectively adsorbing 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, promote the attachment and growth of microorganisms, and further enhance the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through the above synergistic effect, the treatment effect of ammonia nitrogen can be effectively improved.

[0030] The van der Waals force adsorption mentioned above refers to the van der Waals force interaction between the functional group and the ammonia nitrogen molecule. Furthermore, the van der Waals force is an attractive force caused by the dipole-dipole interaction induced between molecules. When the ammonia nitrogen molecule approaches the above functional group, this interaction between them will lead to physical adsorption.

[0031] The electrostatic adsorption mentioned above means that the above functional groups carry partial charges, and the electrostatic interaction between them and the ammonia nitrogen molecules will lead to attraction and promote physical adsorption.

[0032] The hydrogen bond adsorption mentioned above means that the hydrogen atoms in the above functional groups can form hydrogen bonds with the hydrogen atoms or lone pairs of electrons in ammonia nitrogen, thereby promoting the adsorption process.

[0033] Specifically, the present invention 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 an ammonia nitrogen adsorption function, wherein the membrane layer contains a functional group, which is one or more of a hydroxyl group, an amine group or an epoxy group.

[0034] By introducing a membrane layer containing hydroxyl, amine or epoxy groups on the surface of the MABR base membrane (i.e., the porous support layer) with a porous support structure, the groups in the above-mentioned membrane layer can interact with ammonia nitrogen through van der Waals forces, electrostatic effects, and hydrogen bonds, thereby achieving physical adsorption of ammonia nitrogen, promoting ammonia nitrogen to approach the surface of the MABR membrane, and effectively adsorbing ammonia nitrogen near the membrane surface, providing convenient conditions for subsequent treatment; it can also improve the biocompatibility of the membrane surface, promote the attachment and growth of microorganisms, and thereby enhance the oxidation process of ammonia nitrogen by the biofilm on the membrane surface. Through the above-mentioned synergistic effect, the treatment effect of ammonia nitrogen is effectively improved, and the ammonia nitrogen nitrification rate can reach 1.9g N / m 2 / d or more.

[0035] It is worth noting that among the three functional groups mentioned above, the epoxy group has the best adsorption effect on ammonia nitrogen. Under the same conditions, when the functional group is the epoxy group, the ammonia nitrogen treatment effect is better.

[0036] In MABR membrane materials, the porous support layer (i.e., the MABR base membrane with a porous support structure) mainly supports and stabilizes the membrane structure, while ensuring that oxygen and wastewater can be smoothly transferred and reacted through the membrane layer. In MABR membrane technology, the porous support layer is closely combined with the membrane layer containing functional groups (and the biofilm formed thereon) and the aeration membrane, together forming an efficient sewage treatment system. Oxygen is transferred from the aeration membrane to the biofilm through the porous support layer and the membrane layer containing functional groups, providing the microorganisms with the necessary oxygen for metabolic activities and nitrification reactions. At the same time, the pollutants in the wastewater directly contact the biofilm and react with the microorganisms, thereby achieving the removal of ammonia nitrogen.

[0037] The choice of porous support layer materials in the present invention is not limited. For example, common porous support layer materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polydimethylsiloxane (PDMS) and other polymer materials 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.

[0038] The material selection of the membrane layer in the present invention is not particularly limited, and conventional biomembrane materials in the art can be used. For example, in some specific embodiments, the membrane layer material is polyvinylidene fluoride (PVDF), polyethylene (PE), polytetrafluoroethylene membrane (PTFE) or polypropylene (PP).

[0039] Studies have shown that when the surface root mean square roughness of the membrane layer is 80-130nm, the pore size is 0.2-0.5μm, and the contact angle with water is 65-85°, the MABR membrane material has better adsorption performance for ammonia nitrogen and the ammonia nitrogen oxidation efficiency of MABR is higher.

[0040] The present invention also provides a method for preparing the above-mentioned ammonia nitrogen adsorption type MABR membrane material, comprising the following steps: irradiating an organic solvent mixed liquid containing a membrane layer material and a functional group monomer, and coating it on 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 beta rays, gamma rays, and electron beams, the irradiation dose is 40-120 kGy, the irradiation temperature is 0-15°C, and the irradiation time is 60-90 min.

[0041] In the above method, the organic solvent can be selected according to the conventional method in the field, for example, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, methyl tert-butyl ether are usually selected. This is because such organic solvents usually have good solubility and volatility, which are conducive to the dissolution of membrane materials.

[0042] It is worth noting that the organic solvent mixture during irradiation treatment does not contain water. This is because water will affect the solubility of the membrane material in the solvent. At the same time, residual water in the membrane may also affect the air permeability and mechanical properties of the membrane, reduce the treatment efficiency of the MABR system, and make the membrane easily fall off the porous support layer.

[0043] The irradiation treatment controls the atmosphere of the irradiation environment to eliminate the influence of impurities on the reaction process. Specifically, it can be carried out under vacuum conditions to eliminate the interference of gases on the irradiation reaction, or it can be carried out in an inert gas environment, and the inert gas can be one of nitrogen, helium, and argon.

[0044] Furthermore, in order to improve the performance of the film layer, the irradiated mixed solution also contains an additive. For example, in some specific embodiments, polyethylene glycol and / or polyvinyl pyrrolidone are added to improve the flexibility and ductility of the film.

[0045] In some specific embodiments, the organic solvent mixture containing the membrane material and the functional group monomer is prepared by mixing a solution A containing 10-50% by mass of the membrane material and a solution B containing 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 the membrane material and the functional group monomer are fully dissolved and evenly mixed.

[0046] The functional group monomer is selected from hydroxyl group monomers containing hydroxyl groups and / or amine group monomers containing amine groups and / or epoxy group monomers containing epoxy groups. Among them, the hydroxyl group monomer containing hydroxyl groups can be selected from polyvinyl alcohol, hydroxyethyl methacrylate, hydroxyethyl acrylate, 2-hydroxyethyl ether cellulose, the amine group monomer containing amine groups can be selected from polyamide, vinylamine, acrylamine, acrylamide, acrylonitrile, and the epoxy group monomer containing epoxy groups can be selected from ethylene oxide, propylene oxide, epoxypropylene ether, and styrene oxide.

[0047] The present invention adopts the radiation treatment method, and the detailed principle and steps of introducing functional groups are as follows:

[0048] (1) Irradiation treatment to generate free radicals: After the membrane material is mixed with a monomer containing a hydroxyl group, an amine group or an epoxy group, it is exposed to an appropriate radiation source for irradiation treatment. The ionizing radiation acts on the irradiated membrane material, ionizing it and stimulating the release of orbital electrons. The atoms or molecules in the membrane material break and generate free radicals. Taking the membrane materials of polyethylene, polypropylene, polytetrafluoroethylene and polyvinylidene fluoride as examples, the detailed description is as follows:

[0049] When polyethylene (PE) is irradiated, high-energy particles (such as β, γ rays, electron beams, etc.) act on the polyethylene molecular chain to produce two methyl free radicals CH2•;

[0050] When polypropylene (PP) is irradiated, a carbon-carbon double bond in the polypropylene molecule will break, forming a methyl radical (CH3•) and a vinyl radical (CH2=CH2)•;

[0051] When polytetrafluoroethylene (PTFE) is irradiated, 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 the PTFE material to break and generate free radicals, thereby initiating the graft polymerization of monomers on the surface to form two fluorine free radicals (CF2•);

[0052] When polyvinylidene fluoride (PVDF) is irradiated, the carbon-fluorine bond in the polyvinylidene fluoride molecule will break, forming a fluorine free radical (CF2•) and a hydrogen free radical (CHF•).

[0053] (2) Introduction of functional groups and cross-linking reaction: The membrane material generates free radicals under the induction of high-energy rays. The functional groups in the monomer undergo cross-linking addition reaction 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 polymeric membrane material. The free radical R• undergoes cross-linking addition reaction with the functional group (hydroxyl-OH, amine-NH2 or epoxy-O-) to form a new compound R-OH, R-NH2 or RO-, as follows:

[0054] R• + -OH → R-OH;

[0055] R• + -NH 2 → R-NH 2 ;

[0056] 2R• + -O-→ ROR.

[0057] The method of introducing functional groups by irradiation is simple to operate, and the functional groups undergo cross-linking addition reactions with the free radicals of the membrane material to form new chemical bonds, thereby obtaining a three-dimensional cross-linked network structure with functional groups. On the one hand, the mechanical properties, heat resistance and chemical resistance of the original polymer membrane are improved (tensile strength 13~16N), and on the other hand, the compatibility of the functional groups and the membrane materials is improved (surface water contact angle 75°~90°, good hydrophilicity), thereby ensuring the fixation effect and functional stability of the groups, and ensuring that the long-term operation function of the MABR membrane will not be affected. When the functional group is an epoxy group and is introduced by irradiation, the ammonia nitrogen nitrification rate can reach 3.75 g N / m 2 / d or more.

[0058] The MABR membrane prepared by the above method has a surface root mean square roughness of 80-130 nm, a pore size of 0.2-0.5 μm, a surface contact angle of 65°-85°, and is a slightly hydrophilic material with an oxygen transfer rate of 16.53-33.26 g O 2 / (m 2 ·d), the nitrification rate can reach 1.9 g N / (m 2 d) or above.

[0059] The present invention also provides a membrane aerated biofilm reactor, which comprises 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. The reactor has a higher ammonia nitrogen oxidation efficiency.

[0060] The ammonia nitrogen adsorption type MABR membrane material of the present invention is introduced in detail below in conjunction with specific implementation methods.

[0061] Example 1

[0062] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polyethylene) and an outer layer material with a functional group having an ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0063] Step 1, preparation of solution A: dissolve the solute polyethylene (PE) and the auxiliary agent polyvinyl pyrrolidone in the solvent dimethylformamide to form solution A. Specifically, heat in a water bath at 33°C and stir for 18 minutes to completely dissolve the solute in the solvent. Among them, based on the total mass of solution A, the mass fraction of the solute is 28%, and the mass fraction of the auxiliary agent is 16%. The role of the auxiliary agent is to improve the flexibility and ductility of the membrane.

[0064] Step 2, preparation of solution B: dissolving hydroxyethyl methacrylate, a functional group monomer containing hydroxyl groups, in dimethylacetamide solvent to form solution B. Specifically, heating in a water bath at 36°C and stirring by magnetic force for 15 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 20%.

[0065] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 25 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0066] Step 4, irradiation treatment under vacuum conditions to form a MABR membrane material with ammonia nitrogen adsorption function: the radiation source is β rays, the radiation dose is 60kGy, the radiation temperature is 12°C, and the radiation time is 60min. After radiation treatment, it is left to stand at room temperature for 2h for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers a free radical reaction in the membrane material, and then the functional group is introduced to cross-link with the free radicals of the membrane material to form a MABR membrane material with ammonia nitrogen adsorption function.

[0067] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0068] Example 2

[0069] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polypropylene) and an outer layer material with a functional group having an ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0070] 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 the solution in a water bath at 55°C and stir for 30 minutes to completely dissolve the solute in the solvent. The mass fraction of the solute is 40% and the mass fraction of the auxiliary agent is 15% based on the total mass of solution A. The auxiliary agent is used to improve the flexibility and ductility of the membrane.

[0071] Step 2, preparation of solution B: dissolving the functional group monomer containing amino group, acrylamine, in the solvent dimethyl sulfoxide to form solution B. Specifically, heating in a water bath at 45°C and stirring by magnetic force for 20 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 20%.

[0072] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 30 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0073] Step 4, irradiation treatment under vacuum conditions to prepare MABR membrane materials with ammonia nitrogen adsorption function: the radiation source is gamma rays, the radiation dose is 80kGy, the radiation temperature is 10°C, and the radiation time is 75min. After radiation treatment, it is left to stand at room temperature for 2.5h for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers the free radical reaction in the membrane material, and then the functional group is introduced to cross-link with the free radicals of the membrane material to form a MABR membrane material with ammonia nitrogen adsorption function.

[0074] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0075] Example 3

[0076] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polytetrafluoroethylene) and an outer layer material with a functional group having an ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0077] Step 1, preparation of solution A: dissolve the solute polytetrafluoroethylene membrane (PTFE) and the auxiliary agent polyvinyl pyrrolidone in the solvent methyl tert-butyl ether to form solution A. Specifically, heat in a water bath at 35°C and stir for 12 minutes to completely dissolve the solute in the solvent. Among them, based on the total mass of solution A, the mass fraction of the solute is 21%, and the mass fraction of the auxiliary agent is 16%. The role of the auxiliary agent is to improve the flexibility and ductility of the membrane.

[0078] Step 2, preparation of solution B: dissolving ethylene oxide, a functional group monomer containing epoxy groups, in solvent methyl tert-butyl ether to form solution B. Specifically, heating in a water bath at 38°C and stirring by magnetic force for 30 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 25%.

[0079] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 28 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0080] Step 4, irradiation treatment under vacuum conditions to prepare MABR membrane materials with ammonia nitrogen adsorption function: the radiation source is an electron beam, the radiation dose is 100kGy, the radiation temperature is 15°C, and the radiation time is 90min. After radiation treatment, it is allowed to stand at room temperature for 3h for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers a free radical reaction in the membrane material, and then the functional group is introduced to cross-link with the free radicals of the membrane material to form a MABR membrane material with ammonia nitrogen adsorption function.

[0081] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0082] Example 4

[0083] An ammonia nitrogen adsorption type MABR membrane material is composed of a porous support layer (polyvinylidene fluoride) and an outer layer material with a functional group having an ammonia nitrogen adsorption function coated on the surface of the porous support layer. The specific preparation method is as follows:

[0084] Step 1, preparation of solution A: dissolving the solute polyvinylidene fluoride (PVDF) and the auxiliary agent polyvinyl pyrrolidone in the solvent methyl tert-butyl ether to form solution A. Specifically, heating in a water bath at 45° C. and stirring for 15 minutes to completely dissolve the solute in the solvent.

[0085] Wherein, based on the total mass of solution A, the mass fraction of solute is 40%, and the mass fraction of additive is 20%. The role of the additive is to improve the flexibility and ductility of the membrane.

[0086] Step 2, preparation of solution B: dissolving epoxystyrene, a functional group monomer containing epoxy groups, in dimethylacetamide solvent to form solution B. Specifically, heating in a water bath at 55°C and stirring by magnetic force for 30 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 18%.

[0087] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 25 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0088] Step 4, irradiation treatment under vacuum conditions to prepare MABR membrane materials with ammonia nitrogen adsorption function: the radiation source is gamma rays, the radiation dose is 80kGy, the radiation temperature is 12°C, and the radiation time is 80min. After radiation treatment, it is left to stand at room temperature for 3 hours for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers the free radical reaction in the membrane material, and then the functional group is introduced to cross-link with the free radicals of the membrane material to form a MABR membrane material with ammonia nitrogen adsorption function.

[0089] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0090] Example 5

[0091] An ammonia nitrogen adsorption type 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. The difference between the membrane material and Example 3 is that the epoxy functional group monomer is introduced by mixing without irradiation treatment. The specific preparation method is as follows:

[0092] Step 1, preparation of solution A: dissolving the solute polytetrafluoroethylene membrane (PTFE) and the auxiliary agent polyvinyl pyrrolidone in the solvent methyl tert-butyl ether to form solution A. Specifically, heating in a water bath at 35° C. and stirring for 12 minutes to completely dissolve the solute in the solvent.

[0093] Wherein, based on the total mass of solution A, the mass fraction of solute is 21%, and the mass fraction of additive is 16%. The role of the additive is to improve the flexibility and ductility of the membrane.

[0094] Step 2, preparation of solution B: dissolving ethylene oxide, a functional group monomer containing epoxy groups, in solvent methyl tert-butyl ether to form solution B. Specifically, heating in a water bath at 38°C and stirring by magnetic force for 30 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 25%.

[0095] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 28 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C, which was used as the casting solution.

[0096] Step 4, membrane filament preparation: inject the casting liquid into a spinning device containing an inner insert tube, inject an appropriate core liquid (can be one of pure water, methanol, ethanol, isopropanol) into the inner insert tube, the diameter of the inner insert tube is 0.75mm, the casting liquid is extruded vertically downward from the spinneret, and enters the coagulation bath (pure water) after a certain air distance, and instantaneous phase separation gelation occurs in the coagulation bath to form membrane filaments. Among them, the spinning device is preheated for at least 2h before operation, the spinning temperature is 100℃, there is air between the spinneret and the coagulation bath, the vertical spacing distance is controlled to be 1.45m, the spinneret extrusion speed is controlled to be 0.45cm / s, and the coagulation bath temperature is 38℃.

[0097] Step 6, post-processing: placing the obtained membrane filaments in a drying oven for drying, wherein the drying temperature is 65° C. and the drying time is 32 h.

[0098] Comparative Example 1

[0099] A MABR membrane material is composed of 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:

[0100] Step 1, preparation of solution A: dissolving the solute polyethylene (PE) and the auxiliary agent polyvinyl pyrrolidone in the solvent dimethylformamide to form solution A. Specifically, heating in a water bath at 33° C. and stirring for 18 minutes to completely dissolve the solute in the solvent.

[0101] Wherein, based on the total mass of solution A, the mass fraction of solute is 28%, and the mass fraction of additive is 16%. The role of the additive is to improve the flexibility and ductility of the membrane.

[0102] Step 2, preparation of solution B: dissolve acetic acid, a functional group monomer containing carboxyl, in dimethylacetamide, a solvent, to form solution B. Specifically, heat in a water bath at 36°C and stir magnetically for 15 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 20%.

[0103] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 25 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0104] Step 4, irradiation treatment under vacuum conditions to prepare MABR membrane materials: the radiation source is β rays, the radiation dose is 60kGy, the radiation temperature is 12°C, and the radiation time is 60min. After radiation treatment, it is left to stand at room temperature for 2h for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers the free radical reaction in the membrane material, and then the functional group is introduced to cross-link with the free radicals of the membrane material to form the MABR membrane material.

[0105] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0106] Comparative Example 2

[0107] A MABR membrane material is composed of 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:

[0108] Step 1, preparation of solution A: dissolving the solute polypropylene (PP) and the auxiliary agent (polyethylene glycol) in the solvent methyl tert-butyl ether to form solution A. Specifically, heating in a water bath at 55°C and stirring for 30 minutes to completely dissolve the solute in the solvent.

[0109] Wherein, based on the total mass of solution A, the mass fraction of solute is 40%, and the mass fraction of additive is 15%.

[0110] Step 2, preparation of solution B: dissolving the carbonyl-containing functional group monomer acetone in the solvent dimethyl sulfoxide to form solution B. Specifically, heating in a water bath at 45°C and stirring by magnetic force for 20 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 20%.

[0111] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 30 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0112] Step 4, irradiation treatment under vacuum conditions to prepare MABR membrane materials: the radiation source is gamma rays, the radiation dose is 80kGy, the radiation temperature is 10°C, and the radiation time is 75min. After radiation treatment, it is left to stand at room temperature for 2.5h for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers the free radical reaction in the membrane material, and then the functional groups are introduced to cross-link with the free radicals of the membrane material to form the MABR membrane material.

[0113] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0114] Comparative Example 3

[0115] A MABR membrane material is composed of 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:

[0116] Step 1, preparation of solution A: dissolving solute polypropylene (PP) and auxiliary agent polyethylene glycol in solvent methyl tert-butyl ether to form solution A. Specifically, heating in a water bath at 55° C. and stirring for 30 minutes to completely dissolve the solute in the solvent.

[0117] Wherein, based on the total mass of solution A, the mass fraction of solute is 40%, and the mass fraction of additive is 15%. The role of the additive is to improve the flexibility and ductility of the membrane.

[0118] Step 2, preparation of solution B: dissolving isopropylamine, a functional group monomer containing amino groups, in dimethyl sulfoxide solvent to form solution B. Specifically, heating in a water bath at 45°C and stirring by magnetic force for 20 minutes to completely dissolve the solute. The mass fraction of the functional group monomer is 20%.

[0119] Step 3, mixing and stirring: 100 mL of solution A and 80 mL of solution B were magnetically stirred for 30 min to fully mix the two solutions and ensure that solution B was evenly dispersed in solution A to form solution C.

[0120] Step 4, irradiation treatment under vacuum conditions to form MABR membrane material: the radiation source is gamma rays, the radiation dose is 80kGy, the radiation temperature is 10°C, and the radiation time is 75min. After the radiation treatment, it is left to stand at room temperature for 2.5h for degassing treatment to prevent bubbles from affecting the quality and performance of the membrane material. The radiation energy triggers the free radical reaction in the membrane material, and then the functional group is introduced to cross-link with the free radicals of the membrane material to form the MABR membrane material.

[0121] Step 5, coating the obtained MABR membrane material on a porous support layer and drying.

[0122] The above embodiments and comparative examples are summarized in detail in Table 1:

[0123] Table 1

[0124]

[0125] (1) Adsorption experiment

[0126] A 1.2m×1.2m×1.0m organic glass container was filled with an ammonium chloride solution with an ammonia nitrogen concentration of 45 mg / L. The membrane materials prepared according to the methods of the embodiment and the comparative example were placed in different organic glass containers of the same size. After immersion for 15 minutes, samples were taken at positions far from and close to the membrane material to detect the ammonia nitrogen concentration, with points 1 and 4 and points 2 and 3 being axially symmetrical (see Figure 1 ), the test results are as follows Figure 2 shown.

[0127] Depend on Figure 2 It can be seen that the ammonia nitrogen concentration at points 2 and 3 close to the membrane material in Examples 1-5 is significantly higher than that at points 1 and 4 far away from the membrane material, and the difference is more significant in Examples 3-4, while the ammonia nitrogen concentration at points 2 and 3 close to the membrane material in the comparative example is equivalent to the ammonia nitrogen concentration at points 1 and 4 far away from the membrane material, indicating that the membrane material provided in the embodiments of the present invention has a significant function of adsorbing ammonia nitrogen, while the membrane material in the comparative example does not have the function of adsorbing ammonia nitrogen, and when the functional group is an epoxy group (Examples 3 and 4), the adsorption effect is better.

[0128] (2) Operation test

[0129] Take the sludge from the aerobic pool of the sewage treatment plant into a plexiglass container, take the domestic sewage (average ammonia nitrogen concentration 45 mg / L) and pass it into the plexiglass container through the water inlet pump (water inlet flow rate is 50 L / min), and overflow the water. Take the different membrane materials prepared in the embodiment and the comparative example, supply air to the MABR membrane assembly respectively, analyze the effluent water quality, detect the effluent ammonia nitrogen concentration, and calculate the ammonia oxidation efficiency NR of different membrane materials. The results are shown in Table 2 below. Among them,

[0130]

[0131] NHx,inf——ammonia nitrogen concentration entering the organic glass reactor, 45 mg / L;

[0132] NHx,eff——ammonia nitrogen concentration flowing out of the organic glass reactor, mg / L;

[0133] A——MABR membrane area, 100m 2 ;

[0134] Qinf – flow through the MABR reaction unit, 72 m 3 / d;

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

[0136] Table 2

[0137]

[0138] From the above results, it can be seen that when hydroxyl, amine or epoxy groups are introduced into the membrane layer, the nitrification rate of MABR membrane materials can be significantly improved, and the ammonia nitrogen nitrification rate can reach 1.9g N / m 2 / d or more; especially when the introduced group is an epoxy group, the ammonia nitrogen nitration rate is better; and further from Examples 3, 4 and 5, when the functional group is introduced by irradiation, the nitration rate is more significantly improved, and the ammonia nitrogen nitration rate can reach 3.75 g N / m 2 / d or more.

[0139] In addition, it can be seen from the surface contact angle that after the introduction of hydroxyl, amine and epoxy groups in the examples, the water contact angle of the membrane surface is significantly improved, the hydrophilicity is enhanced, which is beneficial to the fixation of microorganisms on the membrane surface and improves the functional stability of the nitrification reaction process, thereby ensuring that the long-term operation function of the MABR membrane will not be affected. Figure 3 , Figure 4 The scanning electron microscope image of the membrane surface also shows that the biofilm has a good biofilm growth effect due to its good hydrophilicity.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an ammonia nitrogen adsorption type MABR membrane material, characterized in that: The following steps are involved: The organic solvent mixture containing the membrane material and the functional group monomer is irradiated and coated on the porous support layer to form the ammonia nitrogen adsorption type MABR membrane material; wherein, during the irradiation treatment, the ambient atmosphere is maintained in 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° C., and the irradiation time is 60-90 min; The functional group monomer is selected from polyvinyl alcohol, hydroxyethyl methacrylate, hydroxyethyl acrylate or 2-hydroxyethyl ether cellulose containing a hydroxyl group; and / or The functional group monomer is selected from polyamide, vinylamine, acrylamine, acrylamide or acrylonitrile containing an amino group; and / or The functional group monomer is selected from ethylene oxide, propylene oxide, epoxypropylene ether or styrene oxide containing epoxy groups.

2. The method for preparing an ammonia nitrogen adsorption type MABR membrane material according to claim 1, characterized in that: The mixed solution also contains an auxiliary agent, which is selected from one or more of polyethylene glycol and polyvinyl pyrrolidone.

3. The method for preparing an ammonia nitrogen adsorption type MABR membrane material according to claim 1 or 2, characterized in that: The organic solvent mixed liquid containing the membrane material and the functional group monomer is formed by mixing a solution A with a membrane material mass fraction of 10-50% and a solution B with a functional group monomer mass fraction of 10-30%, wherein the volume ratio of solution A to solution B is (1-3):

1.

4. The ammonia nitrogen adsorption type MABR membrane material prepared by the method for preparing the ammonia nitrogen adsorption type MABR membrane material according to any one of claims 1 to 3 is characterized in that: It comprises a porous support layer and a membrane layer located on the surface of the porous support layer and having the function of ammonia nitrogen adsorption, wherein the membrane layer contains a functional group, and the functional group is a hydroxyl group or an epoxy group; The membrane layer has a surface root mean square roughness of 80-130 nm, a pore size of 0.2-0.5 μm, and a surface contact angle to water of 65-85°.

5. The ammonia nitrogen adsorption type MABR membrane material according to claim 4, characterized in that: The material of the membrane layer is polyvinylidene fluoride, polyethylene, polytetrafluoroethylene membrane or polypropylene.

6. A membrane aerated biofilm reactor, characterized in that: The invention comprises an ammonia nitrogen adsorption type MABR membrane material prepared by the preparation method according to any one of claims 1 to 3.

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