Janus membrane with anti-pollution capacity in MABR process and preparation method of Janus membrane

Abstract

The invention provides a Janus membrane with anti-pollution capacity in an MABR process and a preparation method, and belongs to the technical field of water treatment. In the preparation process of the Janus membrane, the PP membrane is subjected to thermal oxidation treatment through potassium permanganate, uniform hydrophilic groups and nanoscale manganese dioxide are generated on the single face of the PP membrane, activation of the PP membrane is achieved, operation is easy, materials are easy to obtain, cost is low, and environmental protection is achieved. Meanwhile, the thermal oxidation treatment conditions that the pretreatment temperature is 40-90 DEG C, the pretreatment concentration is 0.1-0.4 M and the pretreatment time is 20-40 min can control the clustering degree of the nanoscale manganese dioxide on the surface of the PP film, and the stability of the surface of the PP film is enhanced. MnO2 on the surface of the PP film and tannin are subjected to a complexation reaction, so that tannin is precipitated on the surface of the PP film. Compared with the condition that manganese oxide is not loaded, more tannin is deposited, and the anti-pollution capacity of the Janus membrane is enhanced. Compared with a fully hydrophobic membrane, the Janus membrane has higher protein pollution resistance, has bubble-free aeration capacity, has high oxygen transfer property, and has developable potential in the field of MABR (Membrane Aerated Baffled Reactor).

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment, and relates to a Janus membrane with anti-pollution capability in a MABR process and a preparation method. BACKGROUND

[0002] MABR (Membrane Aerated Biofilm Reactor) is an advanced biological wastewater treatment technology, which combines a gas separation membrane with a biological membrane reactor, uses the gas permeability of the membrane to provide oxygen for microorganisms, and realizes efficient degradation of pollutants. Therefore, the core of MABR is to supply oxygen to the biological membrane through the gas permeable membrane.

[0003] The bottleneck of MABR development is membrane pollution, that is, the overgrowth of biological membrane and the accumulation of solid substances on the membrane surface will cause an increase in mass transfer resistance, membrane surface blockage, and physical damage to the membrane assembly. Generally, the modification method for resisting membrane pollution is considered to be hydrophilic modification to form a hydration layer. However, MABR membrane is close to liquid phase on one side and close to gas phase on the other side, and the water layer also affects gas mass transfer, affecting the development of MABR.

[0004] Janus membrane is a kind of asymmetric membrane, which is hydrophilic on one side to form a hydration layer to resist membrane pollution, and is hydrophobic on the other side to have good affinity for oil and other non-polar substances, and has good gas mass transfer. Therefore, the hydrophilic and hydrophobic functions of the Janus membrane can match the environment on both sides of MABR, and have high potential in the use of MABR membrane. However, the hydrophobic matrix material has a price difference, resulting in high preparation cost of the Janus membrane. SUMMARY

[0005] The purpose of the present application is to provide a Janus membrane with anti-pollution capability in a MABR process and a preparation method, to solve the problem of high preparation cost of the existing Janus membrane.

[0006] To achieve the above-mentioned purpose, the following technical solutions are adopted in the present application: The present application provides a Janus membrane with anti-pollution capability in a MABR process, which is prepared by surface modification of potassium permanganate solution and surface deposition of tannin, and the modified Janus membrane has bubble-free aeration capability, stable hydrophilic layer, and strong anti-protein pollution capability.

[0007] Specifically, the preparation method of the Janus membrane with anti-pollution capability in the MABR process in the present application comprises: S01: adding potassium permanganate into an acidic solution to form an acidic potassium permanganate solution to improve the oxidation capacity.

[0008] The PP film with micropore diameter of 0.45 μm is washed and prepared for use. Concentrated sulfuric acid is added into water to form an acidic solution. Potassium permanganate is added into the acidic solution and ultrasonically stirred to form a potassium permanganate solution with a molar concentration of 0.1-0.4 M.

[0009] S02: The smooth surface of the PP film is horizontally placed in the potassium permanganate solution at 40-90 o C for 20-40 min, and the PP film is washed to obtain a MnO2 / PP film.

[0010] The potassium permanganate solution is poured into a flat container with a cover, and heated in a water bath to 40-90 o C, and the smooth surface of the PP film is horizontally placed in the potassium permanganate solution for 20-40 min. After the reaction is completed, the potassium permanganate solution remaining on the surface of the PP film is washed to obtain a brown smooth-surfaced MnO2 / PP film, which has a stable MnO2 loaded on the surface.

[0011] The PP film itself can transport water and has a density less than water. When it is placed in the potassium permanganate solution with a density greater than water, it will float on the surface of the potassium permanganate solution, realizing the thermal oxidation modification of the PP film by the potassium permanganate solution and generating uniform hydrophilic groups and nanoscale manganese dioxide on one surface of the PP film. The nanoscale manganese dioxide has a catalytic function, and, since it is in a loaded state, it has a stronger stability than dispersed manganese dioxide particles.

[0012] In the present application, the temperature of the potassium permanganate solution is 40-90 o C, the molar concentration of the potassium permanganate solution is 0.1-0.4 M, and the smooth surface of the PP film is placed in the potassium permanganate solution for 20-40 min. At this time, the nanoscale manganese dioxide has a better cluster structure on the surface of the PP film, enhancing the stability of the surface of the PP film and obtaining a Janus film with the best hydrophilicity and the best modification effect.

[0013] S03: Tannin is added into the acetic acid / sodium acetate buffer solution to form a stable tannin solution.

[0014] An acetic acid solution is prepared in a fume hood, and sodium acetate is added into the acetic acid solution and stirred uniformly to form an acetic acid / sodium acetate buffer solution, wherein the mass / volume ratio of acetic acid to sodium acetate is 0.5-4. Tannin is placed into a container, and the acetic acid / sodium acetate buffer solution is added into the tannin and stirred uniformly to obtain a stable tannin solution with a concentration of 0.01-0.1 g / mL.

[0015] In the present application, the addition of the acetic acid / sodium acetate buffer solution into the tannin can make the tannin dissolve quickly. In actual use, it is found that tannin is easy to oxidize, and therefore the stable tannin solution should be prepared on demand.

[0016] S04: The MnO2 / PP membrane with MnO2 loaded on one side is horizontally placed into the stable tannin solution for 1-2 h at 45-55 o C, and then a sodium periodate solution is added for surface oxidation, and the Janus membrane is obtained after drying at 50-60 o C.

[0017] The stable tannin solution is poured into another glass dish with a lid, and heated in a water bath to 45-55 o C, and then the MnO2 / PP membrane with MnO2 loaded on one side is horizontally placed into the stable tannin solution for 1-2 h to allow complexation reaction between MnO2 and tannin, and then the tannin is precipitated on the surface of the PP membrane. After the complexation reaction is completed, a sodium periodate solution with a concentration of 0.1-1 g / L is added to the reaction system to oxidize the tannin on the surface of the PP membrane, and then more hydrophilic carboxyl groups are generated in the tannin deposition layer. The modified PP membrane is dried at 50-60 o C for 2 h to obtain a Janus membrane with one side of tannin oxide and the other side of hydrophobicity.

[0018] The Janus membrane with anti-pollution ability in the MABR process in the present application is used in a membrane aerated biofilm reactor for treating wastewater, especially wastewater containing proteins.

[0019] The Janus membrane with anti-pollution ability in the MABR process in the present application is used as an aeration membrane in a membrane aerated biofilm reactor.

[0020] The present application has the following beneficial effects: (1) In the present application, the PP membrane is treated by hot oxidation of potassium permanganate to generate uniform hydrophilic groups and nanoscale manganese dioxide on one side of the PP membrane, thereby realizing activation of the PP membrane. The operation is simple, the material is easy to obtain, the cost is low, and the process is green and environmentally friendly. At the same time, the hot oxidation treatment conditions of temperature 60-90 o C, concentration 0.2-0.3 M, and treatment time 30-50 min can control the clustering degree of nanoscale manganese dioxide on the surface of the PP membrane, thereby enhancing the stability of the surface of the PP membrane.

[0021] (2) In the present application, the MnO2 on the surface of the PP membrane is allowed to undergo complexation reaction with tannin, so that the tannin is precipitated on the surface of the PP membrane. Compared with not loading manganese oxide, more tannin is deposited, thereby strengthening the anti-pollution ability of the Janus membrane.

[0022] (3) In the present application, the tannin on the surface of the PP membrane is oxidized by a sodium periodate solution to promote self-polymerization of the tannin deposition layer and generate more hydrophilic carboxyl groups.

[0023] (4) Compared with the full hydrophobic membrane, the Janus membrane has stronger anti-protein pollution ability, and has the ability of bubbleless aeration, high oxygen transmission, and potential development in the field of MABR. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The water contact angle detection diagram of the Janus membrane prepared by different concentrations and temperatures of potassium permanganate solution; Figure 2 The SEM (Scanning Electron Microscope) diagram of the PP membrane and the Janus membrane prepared in Example 4; wherein, a-c are the SEM diagrams of the PP membrane under magnifications of 1000, 5000 and 10000 times, respectively, and d-f are the SEM diagrams of the Janus membrane under magnifications of 1000, 5000 and 10000 times, respectively; Figure 3 The MABR assembly diagram of the PP membrane and the Janus membrane assembly prepared in Example 4; Figure 4 The nitrogen removal efficiency comparison diagram of the PP membrane and the Janus membrane prepared in Example 4; Figure 5 The change diagram of each component during the operation of the Janus membrane prepared in Example 4. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be further explained and described below through specific examples.

[0026] Example 1 The Janus membrane with anti-pollution ability in the MABR process provided by the embodiments of the present application, and the preparation method of the Janus membrane comprises: S101: After washing the PP membrane with a micropore aperture of 0.45 μm, it is ready for use. 2 mL of concentrated sulfuric acid is added to 600 mL of water to form an acidic solution. 9.48 g of potassium permanganate is added to the acidic solution and ultrasonically stirred to form an acidic potassium permanganate solution with a molar concentration of 0.1 M.

[0027] S102: Pour the acidic potassium permanganate solution into a flat plate covered container, and heat it to 40 o C in a water bath, and then place the PP membrane smooth surface horizontally in the acidic potassium permanganate solution for 30 min. After the placement is completed, wash the surface of the PP membrane to remove the residual acidic potassium permanganate solution, and obtain a brown smooth surface MnO2 / PP membrane, which has a stable MnO2 loaded on the surface.

[0028] S103: 20 mL of acetic acid was added to 980 mL of water, and 16.4 g of sodium acetate was added and stirred to form 1 L of acetic acid / sodium acetate buffer. The tannin was placed in a container, 100 mL of the acetic acid / sodium acetate buffer was added to 6 g of tannin, and stirred to obtain a stable tannin solution with a concentration of 0.06 g / mL.

[0029] S104: The stable tannin solution was poured into another flat-lidded container, and heated to 45 o C, and the side of the MnO2 / PP film loaded with MnO2 was placed horizontally in the stable tannin solution for 1 h. Then, 10 mL of a sodium periodate solution with a concentration of 0.1 g / L was added to the reaction system to oxidize the tannin on the surface of the PP film for 5 min. The modified PP film was dried at 50 o C for 2 h to obtain a Janus film with tannin oxide on one side and hydrophobicity on the other side.

[0030] Example 2 The embodiments of the present application provide a Janus film with anti-pollution capability in a MABR process, and a preparation method of the Janus film comprises the following steps: S201: A PP film with a micropore size of 0.45 μm was washed and prepared. 2 mL of concentrated sulfuric acid was added to 600 mL of water to form an acid solution. 9.48 g of potassium permanganate was added to the acid solution and ultrasonically stirred to form an acid potassium permanganate solution with a molar concentration of 0.1 M.

[0031] S202: The acid potassium permanganate solution was poured into a flat-lidded container, and heated to 50 o C in a water bath, and the smooth surface of the PP film was placed horizontally in the acid potassium permanganate solution for 30 min. After the placement was completed, the acid potassium permanganate solution remaining on the surface of the PP film was washed to obtain a brown smooth-surfaced MnO2 / PP film, and the MnO2 / PP film was loaded with stable MnO2 on the surface.

[0032] S203: 20 mL of acetic acid was added to 980 mL of water, and 16.4 g of sodium acetate was added and stirred to form 1 L of acetic acid / sodium acetate buffer. 6 g of tannin was placed in a container, and 100 mL of the acetic acid / sodium acetate buffer was added to the tannin and stirred to obtain a stable tannin solution with a concentration of 0.06 g / mL.

[0033] S204: The stable tannin solution was poured into another flat-lidded container, and heated to 45 oC, the MnO2 / PP film side loaded with MnO2 was placed horizontally into the stable tannin solution for 1 h. Then, 10 mL of 0.1 g / L sodium periodate solution was added to the reaction system to oxidize the tannin on the surface of the PP film for 5 min. The modified PP film was dried at 50 o C for 2 h to obtain a Janus film with one side of tannin oxide and the other side of hydrophobicity.

[0034] Example 3 The embodiment of the present application provides a Janus film with anti-pollution ability in a MABR process, and a preparation method of the Janus film comprises the following steps: S301: a PP film with a micropore aperture of 0.45 μm was washed and prepared. 2 mL of concentrated sulfuric acid was added into 600 mL of water to form an acid solution. 18.96 g of potassium permanganate was added into the acid solution and ultrasonically stirred to form an acid potassium permanganate solution with a molar concentration of 0.2 M.

[0035] S302: the acid potassium permanganate solution was poured into a flat container with a cover, and heated in a water bath to 60 o C, the PP film was placed horizontally into the acid potassium permanganate solution for 20 min. After the placement was completed, the acid potassium permanganate solution remaining on the surface of the PP film was washed to obtain a brown smooth-surfaced MnO2 / PP film, and the MnO2 / PP film was loaded with stable MnO2 on the surface.

[0036] S303: 20 mL of acetic acid was added into 980 mL of water, and then 16.4 g of sodium acetate was added and stirred uniformly to form 1 L of an acetic acid / sodium acetate buffer. 6 g of tannin was placed into a container, 100 mL of the acetic acid / sodium acetate buffer was added into the tannin, and the mixture was stirred uniformly to obtain a stable tannin solution with a concentration of 0.06 g / mL.

[0037] S304: the stable tannin solution was poured into another flat container with a cover, and heated in a water bath to 50 o C, the MnO2 / PP film side loaded with MnO2 was placed horizontally into the stable tannin solution for 1 h. Then, 10 mL of 0.1 g / L sodium periodate solution was added to the reaction system to oxidize the tannin on the surface of the PP film for 5 min. The modified PP film was dried at 50 o C for 2 h to obtain a Janus film with one side of tannin oxide and the other side of hydrophobicity.

[0038] Example 4 The embodiment of the present application provides a Janus film with anti-pollution ability in a MABR process, and a preparation method of the Janus film comprises the following steps: S401: After washing the PP film with a micropore aperture of 0.45 μm, it is ready for use. 2 mL of concentrated sulfuric acid is added to 600 mL of water to form an acidic solution. 18.96 g of potassium permanganate is added to the acidic solution and ultrasonically stirred to form an acidic potassium permanganate solution with a molar concentration of 0.2 M.

[0039] S402: The acidic potassium permanganate solution is poured into a flat container with a lid, and heated to 70 o C in a water bath. The smooth surface of the PP film is then placed horizontally in the acidic potassium permanganate solution for 30 min. After the placement is complete, the residual acidic potassium permanganate solution on the surface of the PP film is washed, and a brown smooth-surfaced MnO2 / PP film is obtained, which has stable MnO2 loaded on the surface.

[0040] S403: 20 mL of acetic acid is added to 980 mL of water, and 16.4 g of sodium acetate is then added and stirred uniformly to form a 1 L acetic acid / sodium acetate buffer. 6 g of tannin is placed in a container, and 100 mL of the acetic acid / sodium acetate buffer is added to the tannin and stirred uniformly to obtain a stable tannin solution with a concentration of 0.06 g / mL.

[0041] S404: The stable tannin solution is poured into another flat container with a lid, and heated to 50 o C in a water bath. The side of the MnO2 / PP film loaded with MnO2 is then placed horizontally in the stable tannin solution for 1 h. Then, 10 mL of a sodium periodate solution with a concentration of 0.1 g / L is added to the reaction system to oxidize the tannin on the surface of the PP film for 5 min. The modified PP film is dried at 55 o C for 2 h to obtain a Janus film with one side being tannin oxide and the other side being hydrophobic.

[0042] Example 5 The embodiments of the present application provide a Janus film with anti-pollution capability in a MABR process, and a preparation method of the Janus film comprises the following steps: S501: After washing the PP film with a micropore aperture of 0.45 μm, it is ready for use. 2 mL of concentrated sulfuric acid is added to 600 mL of water to form an acidic solution. 9.48 g of potassium permanganate is added to the acidic solution and ultrasonically stirred to form an acidic potassium permanganate solution with a molar concentration of 0.1 M.

[0043] S502: The acidic potassium permanganate solution is poured into a flat container with a lid, and heated to 80 o C in a water bath. The smooth surface of the PP film is then placed horizontally in the acidic potassium permanganate solution for 30 min. After the placement is complete, the residual acidic potassium permanganate solution on the surface of the PP film is washed, and a brown smooth-surfaced MnO2 / PP film is obtained, which has stable MnO2 loaded on the surface.

[0044] S503: 20 mL of acetic acid was added to 980 mL of water, and 16.4 g of sodium acetate was added and stirred to form 1 L of acetic acid / sodium acetate buffer. 6 g of tannin was placed in a container, 100 mL of acetic acid / sodium acetate buffer was added to the tannin, and stirred to obtain a stable tannin solution with a concentration of 0.06 g / mL.

[0045] S504: The stable tannin solution was poured into another flat-lidded container, and heated to 50 o C, and the side of the MnO2 / PP film loaded with MnO2 was placed horizontally in the stable tannin solution for 1.5 h. Then, 10 mL of sodium periodate solution with a concentration of 0.1 g / L was added to the reaction system to oxidize the tannin on the surface of the PP film for 5 min. The modified PP film was dried at 55 o C for 2 h to obtain a Janus film with tannin oxide on one side and hydrophobic on the other side.

[0046] Example 6 The embodiments of the present application provide a Janus film with anti-pollution ability in a MABR process, and a preparation method of the Janus film comprises the following steps: S601: A PP film with a micropore size of 0.45 μm was washed and prepared. 2 mL of concentrated sulfuric acid was added to 600 mL of water to form an acid solution. 37.92 g of potassium permanganate was added to the acid solution and ultrasonically stirred to form an acid potassium permanganate solution with a molar concentration of 0.4 M.

[0047] S602: The acid potassium permanganate solution was poured into a flat-lidded container, and heated to 90 o C in a water bath, and the smooth surface of the PP film was placed horizontally in the acid potassium permanganate solution for 40 min. After the placement was completed, the acid potassium permanganate solution remaining on the surface of the PP film was washed to obtain a brown smooth-surfaced MnO2 / PP film, and the MnO2 / PP film was loaded with stable MnO2 on the surface.

[0048] S603: 20 mL of acetic acid was added to 980 mL of water, and 16.4 g of sodium acetate was added and stirred to form 1 L of acetic acid / sodium acetate buffer. 6 g of tannin was placed in a container, 100 mL of acetic acid / sodium acetate buffer was added to the tannin, and stirred to obtain a stable tannin solution with a concentration of 0.06 g / mL.

[0049] S604: The stable tannin solution was poured into another flat-lidded container, and heated to 55 oC, the MnO2 / PP film was placed horizontally into the stable tannin solution for 2 h. Then, 10 mL of 0.1 g / L sodium periodate solution was added into the reaction system to oxidize the tannin on the surface of the PP film for 5 min. The modified PP film was dried at 60 o C for 2 h to obtain a Janus film with one side of tannin oxide and the other side of hydrophobicity.

[0050] To verify the temperature of the acidic potassium permanganate solution is 70 o C, the molar concentration of the acidic potassium permanganate solution is 0.2 M, and the time of the smooth surface of the PP film in the acidic potassium permanganate solution is 30 min, the Janus film has the optimal hydrophilicity and modification effect. In the present application, the acidic potassium permanganate solutions with the molar concentrations of 0.1 M, 0.2 M, 0.3 M, and 0.4 M were respectively configured, and the steps in Example 1 were followed to heat in the water bath to 40 o C, 50 o C, 60 o C, 70 o C, 80 o C, 90 o C, and the smooth surface of the PP film was placed horizontally into the acidic potassium permanganate solution for 30 min to obtain the Janus film. The water contact angles of the PP film and the Janus films were respectively tested to obtain the following Figure 1 .

[0051] As shown in the following Figure 1 , the water contact angle of the PP film is 136.4°. When the heating temperature in the water bath is 40 o C, the water contact angles of the Janus films change little. When the heating temperature in the water bath is 50-80 o C, the water contact angles of the Janus films are stable below 60°. When the heating temperature in the water bath is 90 o C, the water contact angles of the Janus films rise to 75°. This indicates that the surface hydrophilicity of the Janus film presents a trend of first decreasing and then increasing with the temperature of the acidic potassium permanganate solution treating the PP film.

[0052] The present application also performed SEM detection on the Janus film and the PP film prepared in Example 4 to obtain the following Figure 2 . As shown in the following Figure 2 , the surface of the PP film is rough with small granular substances, while the surface of the Janus film prepared in Example 4 is smooth without small granular substances. This indicates that the complex deposition of manganese dioxide and tannin makes the surface of the PP film smooth, thereby improving the hydrophilicity.

[0053] In addition, the application examples also respectively take the Janus film prepared in Example 4 as an example to carry out the pollutant treatment, OTR (Chinese name: oxygen transmission rate) test and sewage treatment test, and the specific content is: 1. Pollutant treatment The bovine serum albumin-PBS buffer with a concentration of 1 g / L is configured as a pollution source. The PP film, the MnO2 / PP film in Example 4 and the Janus film prepared in Example 4 are respectively immersed in the bovine serum albumin-PBS buffer for 24 h. After the immersion is completed, the ultraviolet Bradford method is used to calculate the adsorption amount of the bovine serum albumin in the bovine serum albumin-PBS buffer by each film. It is calculated that the adsorption amount of the bovine serum albumin in the bovine serum albumin-PBS buffer by the PP film, the MnO2 / PP film and the Janus film is 758 ug / cm 2 , 93 ug / cm 2 , 396 ug / cm 2 respectively. Thus, it is shown that the MnO2 / PP film and the Janus film have better anti-protein pollution ability than the PP film. Because the nano manganese dioxide exists on the surface of the MnO2 / PP film, it makes it difficult for the bovine serum albumin to be adsorbed on the surface of the MnO2 / PP film, and thus the adsorption amount of the bovine serum albumin is less than that of the Janus film. Because the Janus film surface contains a large number of hydrophilic carboxyl groups, when the Janus film is immersed in the pollution source, OH in the hydrophilic carboxyl group combines with water molecules as a hydrogen bond acceptor to generate a hydration layer. The hydration layer has steric hindrance, so the Janus film must push away the hydration layer when adsorbing the bovine serum albumin. The process of pushing away the hydration layer needs a large amount of energy, and the enthalpy change is greater than 0. The protein adsorption process is an entropy reduction process with a decrease in conformational freedom, and the overall adsorption process has a Gibbs free energy greater than zero, which is a non-spontaneous process with an increase in Gibbs free energy, and thus the Janus film is less polluted by the bovine serum albumin.

[0054] 2. OTR test The bubble point and bubbleless aeration OTR tests of the PP film, the MnO2 / PP film in Example 4 and the Janus film prepared in Example 4 are carried out by using the OTR test device made by the laboratory. Specifically, the air pressure of the OTR test device is gradually increased, the bubble point is tested as the bubble point, the total mass transfer coefficient KLa in the assembly is calculated, and the oxygen transfer rate OTR is obtained after temperature and pressure correction. The calculation formula of the total mass transfer coefficient KLa is lg(Cs-Ct) / (Cs-C0)-t, Cs is the saturated dissolved oxygen in pure water at the test temperature, Ct is the dissolved oxygen concentration in water at t, C0 is the dissolved oxygen concentration in water at the beginning of the test, and t is the aeration time. It is calculated that the bubble point of the PP film is 0, the bubbleless aeration OTR=0 gO2 / (m t 2 ​d); The bubble point of the MnO2 / PP membrane is 5 kPa, and the OTR of bubble-free aeration is 26.06 gO2 / (m 2 ∙d); The bubble point of the Janus membrane is 12 kPa, and the OTR for bubble-free aeration is 7.85 gO2 / (m³). 2 •d). This indicates that after tannin modification, the bubble point of the Janus membrane is significantly increased, meeting the requirements for bubble-free aeration. The process requirements can be achieved through simple modification such as pre-oxidation activation. However, excessive tannin deposition during hydrophilic modification may clog the pores of the Janus membrane, leading to reduced oxygen mass transfer and a lower OTR than the pre-oxidized state. It is necessary to change the parameters to balance the slightly contradictory performance of bubble point and oxygen mass transfer.

[0055] 3. Wastewater treatment Using PP membrane and Janus membrane prepared in Example 4 as aeration membranes, respectively, with activated sludge attached to the outer membrane, the resulting product was... Figure 3 The apparatus is shown. After operating under the same conditions for 15 days, the ammonia nitrogen conversion efficiency of both apparatuses was calculated (see attached diagram). Figure 4 The changes in chemical oxygen demand (COD), ammonium nitrogen, nitrate nitrogen, and nitrite nitrogen in the Janus membrane are shown in the attached figure. Figure 5 As shown.

[0056] From the appendix Figure 4 It can be seen that the ammonium nitrogen degradation rate of the PP membrane is 60%, while that of the Janus membrane is 95%, an increase of 35%. This indicates that when the Janus membrane prepared in Example 4 of this application is used as an aeration membrane, the oxygen mass transfer effect is significantly improved, and the ammonia nitrogen conversion efficiency is increased.

[0057] From the appendix Figure 5 It is evident that in the first 4 hours of operation, the high COD concentration in the wastewater enhances the activity of heterotrophic bacteria, which compete with nitrifying bacteria for dissolved oxygen. This prevents aerobic nitrifying bacteria from fully exerting their function, thus delaying the nitrification process of ammonia nitrogen. Therefore, appropriate control of the aeration rate can effectively achieve nitrite accumulation, making an integrated anaerobic ammonia oxidation process possible. Monitoring the changes in COD, DO, ammonium nitrogen, nitrate nitrogen, and nitrite nitrogen in the Janus membrane can provide a reference for adjusting the aeration mode of the MABR module.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a Janus membrane with anti-fouling ability in a MABR process, characterized in that, The method comprises the following steps: adding potassium permanganate into an acid solution to form an acid potassium permanganate solution with a concentration of 0.1-0.4 M; Place the PP membrane smooth side horizontally into 40-90 o C for 20-40 min in the acidic KMnO4 solution, and obtain MnO2 / PP membrane after washing; adding an acetic acid / sodium acetate buffer into tannin to form a stable tannin solution; The Mn02 / PP film with Mn02-loaded side was placed horizontally into 40-60 o C for 1-2 h, and then a sodium periodate solution was added for surface oxidation, and the Janus film was obtained after drying at 50-60 o C.

2. The method of claim 1, wherein the Janus membrane having anti-fouling ability in the MABR process is prepared by, temperature of the potassium permanganate solution is 40-90 o C, the molar concentration is 0.1-0.4 M; the time of the smooth surface of the PP film in the potassium permanganate solution is 30 min.

3. The method of claim 1, wherein the Janus membrane having anti-fouling ability in the MABR process is prepared by, the concentration of the sodium periodate solution is 0.1-1 g / L, and the concentration of the stable tannin solution is 0.01-0.1 g / mL.

4. The method of claim 1, wherein the Janus membrane having anti-fouling ability in the MABR process is prepared by, The acetic acid / sodium acetate buffer is prepared by adding acetic acid into water and then adding sodium acetate to form the acetic acid / sodium acetate buffer.

5. The method of claim 4, wherein the Janus membrane has an anti-fouling ability. The mass-volume ratio of the acetic acid and the sodium acetate is between 0.5 and 4.

6. The method of claim 1, wherein the Janus membrane having anti-fouling ability in the MABR process is prepared by, The micropore diameter of the PP film is 0.45 μm.

7. The Janus membrane with anti-fouling ability in the MABR process prepared by the preparation method in any one of claims 1-6.

8. The Janus membrane with anti-fouling ability in the MABR process in claim 7 is applied to MABR treatment of sewage.

9. The Janus membrane with anti-fouling ability in the MABR process in claim 7 is used as an aeration membrane in the MABR process.

10. The Janus membrane with anti-fouling ability in the MABR process prepared according to claim 7, characterized in that, The reverse side is made of polypropylene, is hydrophobic and air-permeable, and the other side is complexed with manganese oxide and tannin, and the tannin is self-polymerized by oxidation to form a hydrophilic network and anti-fouling.

Images