A rapid-startup oriented embedded microbial membrane for MABR and its application

Abstract

The present invention belongs to the technical field of water treatment, and provides a rapidly starting and directionally embedded microbial membrane for MABR and its application. The above-mentioned rapidly starting and directionally embedded microbial membrane can be prepared by the following method: (1) spraying a binder on a substrate, fixing short fibers on a flocked cloth substrate by electrostatic flocking, and removing suspended short fibers after curing to obtain a flocked cloth; (2) sequentially fixing aerobic activated sludge, facultative activated sludge, and anaerobic activated sludge on the surface of the flocked cloth. The biological membrane of the present invention is used in a membrane aeration bioreactor, which greatly improves the nitrification and denitrification efficiency in the initial stage and is equivalent to the efficiency after 40 days of operation of a traditional membrane aeration bioreactor. This biological membrane enhances the synergy between different functional microbial communities, improves the activity of microorganisms, protects the biological membrane from falling off, and improves the efficiency of biological water treatment; there is no need for a reflux and stirring device, and the aeration pressure is low, reducing the energy consumption of sewage treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and relates to a method for quickly starting a MABR (Membrane Aerated Biofilm Reactor) for directionally embedding microbial membranes and its application in the nitrification and denitrification stages of sewage treatment. Background Art

[0002] The MABR (Membrane Aerated Biofilm Reactor) technology is a novel sewage biological treatment technology that combines sewage treatment and gas separation membrane technology. Compared with traditional biofilm processes, it has the following advantages: 1) a unique microbial redox stratified structure, enabling efficient total nitrogen removal at a low carbon-nitrogen ratio through simultaneous nitrification and denitrification; 2) a large specific surface area of hollow fiber membranes, which is conducive to the accumulation of biomass, and microorganisms attach and grow on the surface of the membrane without being washed away by aeration; 3) bubbleless aeration with high dissolved oxygen efficiency and low energy consumption. As an energy-efficient and nitrogen-removing technology, MABR has received increasing attention. However, there are still problems to be solved in the MABR process, and the most prominent one is that the biofilm formation period is very long, requiring 30 - 40 days, which leads to a long start-up time for the MABR process.

[0003] Chinese Patent CN106947754A discloses a highly efficient microbial gel embedding agent and its preparation method. The gel includes an embedding agent, a cross-linking agent, and activated sludge strains. The embedding agent is polyvinyl alcohol, sodium alginate, and β-cyclodextrin, and the cross-linking agent includes a mixture of calcium chloride and saturated boric acid or a mixture of calcium chloride and sodium nitrate. It enhances the sewage denitrification effect and the removal efficiency of organic matter, while also enhancing the adsorption performance and microbial activity of the gel, improving the removal efficiency of pollutants. This patent does not mention the process of fixing on a support.

[0004] Chinese Patent CN11512107A discloses a three-layer embedding method and application for enhancing the stability of microbial agents. The bacterial sludge is mixed with the first-layer embedding protective agent to obtain the first-layer embedded treated bacterial liquid; the first-layer embedded treated bacterial liquid is mixed with the second-layer embedding protective agent to obtain the second-layer embedded treated bacterial liquid; the second-layer embedded treated bacterial liquid is mixed with the third-layer embedding protective agent to obtain the third-layer embedded emulsified bacterial liquid; then the third-layer embedded emulsified bacterial liquid is subjected to cryogenic granulation and drying. The application of the three-layer embedding method in microbial agents is to improve the stability of microbial agents, extend the shelf life of microbial agents, and improve the use effect of microbial agents. This patent does not mention the process of fixing on a support.

[0005] Chinese Patent CN116216918A discloses a processing equipment, method and product of a C-shaped ring biological filler with surface flocking. Electrostatic flocking technology utilizes the physical property of like charges repelling and opposite charges attracting. It makes the fluff carry a negative charge. The object to be flocked is placed under zero potential or grounded conditions. The fluff is attracted by the object to be flocked with different potential and accelerates vertically to fly onto the surface of the object to be flocked. Since the object to be flocked is coated with an adhesive, the fluff is vertically adhered to the object to be flocked. Therefore, electrostatic flocking is a new production process generated by utilizing the natural properties of charges. This patent does not mention the process of embedding microorganisms. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for quickly starting a membrane aeration bioreactor to directionally embed a microbial membrane, which can be used in the initial stage of the membrane aeration bioreactor, improve the removal efficiency of nitrification and denitrification reactions, and enhance the synergy between microorganisms.

[0007] Another purpose of the present invention is to provide a preparation method for the above-mentioned method of quickly starting a membrane aeration bioreactor to directionally embed a microbial membrane.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions.

[0009] A preparation method for quickly starting and directionally embedding a microbial membrane for a membrane aeration bioreactor, comprising the following steps:

[0010] (1) Spray the binder on the flocked cloth substrate, then fix the short fibers on the flocked cloth substrate by electrostatic flocking, and remove the suspended short fibers after curing to obtain the flocked cloth;

[0011] (2) Fix aerobic activated sludge, facultative activated sludge, and anaerobic activated sludge on the surface of the flocked cloth in sequence.

[0012] The binder is selected from polyurethane flocking glue or acrylate flocking glue.

[0013] The flocked cloth substrate is non-woven fabric or knitted fabric.

[0014] The material of the short fibers is one or more of polyester fiber, polyvinyl alcohol fiber, polyamide fiber, polyacrylonitrile fiber, polypropylene fiber, and polyvinyl chloride fiber.

[0015] The diameter of the short fibers is 20 - 50 μm, preferably 30 μm; the length is 30 - 100 mm, preferably 50 mm.

[0016] The thickness of the aerobic activated sludge, facultative activated sludge, or anaerobic activated sludge on the flocked cloth is 1 - 5 mm, preferably 2 mm.

[0017] To prevent the loss of activated sludge, the above preparation method further includes step (3): adding a photosensitizer to an aqueous solution of polyvinyl alcohol to obtain a hydrogel prepolymer solution, and then placing it on the surface of the flocked cloth in step (2) and performing photocuring.

[0018] The photosensitizer is one or two of N-methyl-4-(p-formylstyryl)pyridinium methyl sulfate, 3-methoxydiphenylamine-4-diazonium salt, and 4-diazodiphenylamine hydrogen sulfate, preferably N-methyl-4-(p-formylstyryl)pyridinium methyl sulfate.

[0019] The degree of hydrolysis of the polyvinyl alcohol is 88%.

[0020] The mass ratio of the photosensitizer to polyvinyl alcohol is 0.1-1:100.

[0021] The mass ratio of the polyvinyl alcohol to water is 10-15:85-90.

[0022] A rapidly-starting directionally-embedded microbial membrane prepared by the above method.

[0023] An application of the above rapidly-starting directionally-embedded microbial membrane in sewage treatment, including the following steps: assembling the rapidly-starting directionally-embedded microbial membrane on a membrane aeration bioreactor for aeration, performing a biological reaction under appropriate pressure and temperature, and denitrifying the sewage.

[0024] The present invention has the following advantages:

[0025] During the process of preparing the directionally-embedded microbial membrane of the present invention, short fibers are added, which can protrude fluffy protrusions on the surface of the flocked cloth, increasing the specific surface area for microorganisms to attach; and a biological membrane is embedded before operation, greatly shortening the reaction startup time; aerobic sludge, facultative sludge, and anaerobic sludge simultaneously play roles in the sewage treatment system, synchronously realizing nitrification and denitrification, and efficiently degrading nitrogen; the outermost layer of the biological membrane is covered with a hydrogel layer, which can prevent the loss of the underlying sludge layers and does not affect the normal mass transfer during sewage treatment; when this biological membrane is used in a membrane aeration bioreactor, the nitrification and denitrification efficiencies in the initial stage of the membrane aeration reactor are greatly improved, equivalent to the efficiency after 40 days of operation of a traditional membrane aeration bioreactor; using this directionally-embedded microbial membrane technology enhances the synergistic effect between different functional microbial communities, improves the activity of microorganisms, and protects the biological membrane from falling off, improving the efficiency of biological water treatment; and there is no need for a reflux and stirring device, and the aeration pressure is low, greatly reducing the energy consumption of sewage treatment. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the directionally-embedded microbial membrane;

[0027] Figure 2is the ammonia nitrogen removal rate of each treatment;

[0028] Figure 3 is the total nitrogen removal rate of each treatment;

[0029] Figure 4 is the COD removal rate of each treatment. Specific embodiments

[0030] The present invention will be further described below in conjunction with embodiments and drawings, but the present invention is not limited by the following embodiments.

[0031] Example 1 Preparation of oriented embedded microbial film

[0032] 1. Preparation of flocked cloth

[0033] (1) Glue spraying: Uniformly spray polyurethane flocking glue on the knitted cloth;

[0034] (2) Electrostatic flocking coating: Hang the flocked cloth substrate coated with the binder into the electrostatic processing equipment, put short fibers with a diameter of 30μm and a length of 50mm into the hopper of the electrostatic processing equipment, turn on the electrostatic processing equipment, adjust the voltage to 15KV according to the operating procedures, run for 60s, and turn off the electrostatic processing equipment;

[0035] (3) Drying: Put the flocked short fiber-flocked cloth into a 60°C dryer and dry for 30 minutes;

[0036] (4) Removing floating fluff: Use a vacuum cleaner to remove the short fibers that are not adhered or are not firmly adhered to obtain the flocked cloth.

[0037] 2. Preparation of hydrogel prepolymer solution

[0038] (1) Weigh polyvinyl alcohol with a hydrolysis degree of 88% and water according to a mass ratio of 15:85, place it in a dry three-necked flask, and soak for 6h to swell;

[0039] (2) Under stirring conditions, reflux at 60°C until completely dissolved;

[0040] (3) After cooling to 25°C, add 1% of the mass of polyethanol as the photosensitizer N-methyl-4-(p-formylstyryl) pyridinium methyl sulfate, and continue stirring in the dark for 1h.

[0041] (4) Pour it into a container and let it stand in the dark to defoam.

[0042] 3. Sludge immobilization

[0043] (1) At 25°C, pass a suspension of aerobic activated sludge with a thickness of 2mm through a suction filter and fix it on the flocked cloth until the surface is anhydrous;

[0044] (2) Pass the facultative activated sludge suspension with a thickness of 2 mm through a suction filter, and continue to fix it on the flocked cloth in step (1) until the surface is water-free;

[0045] (3) Pass the anaerobic activated sludge suspension with a thickness of 2 mm through a suction filter, and continue to fix it on the flocked cloth in step (2) until the surface is water-free;

[0046] (4) Immerse the flocked cloth in step (3) in the hydrogel prepolymer solution for 5 s, fully soak it, take it out, place it under a fluorescent lamp for 24 hours to cure, and store it in a 4°C refrigerator for standby.

[0047] Example 2 Preparation of Oriented Embedded Microbial Membrane

[0048] 1. Preparation of Flocked Cloth

[0049] (1) Glue spraying: Uniformly spray polyurethane flocking glue on the knitted cloth;

[0050] (2) Electrostatic flocking coating: Hang the flocked cloth substrate after applying the binder into the electrostatic processing equipment, put the short fibers with a diameter of 30 μm and a length of 50 mm into the hopper of the electrostatic processing equipment, turn on the electrostatic processing equipment, adjust the voltage to 15 KV according to the operating procedures, run for 60 s, and turn off the electrostatic processing equipment;

[0051] (3) Drying: Put the flocked short fiber-flocked cloth into a 60°C dryer and dry for 30 min;

[0052] (4) Removing floating fluff: Use a vacuum cleaner to remove the short fibers that are not adhered or adhered loosely to obtain the flocked cloth.

[0053] 2. Sludge Immobilization

[0054] (1) At 25°C, pass the aerobic activated sludge suspension with a thickness of 1 mm through a suction filter and fix it on the flocked cloth until the surface is water-free;

[0055] (2) Pass the facultative activated sludge suspension with a thickness of 1 mm through a suction filter and continue to fix it on the flocked cloth in step (1) until the surface is water-free;

[0056] (3) Pass the anaerobic activated sludge suspension with a thickness of 1 mm through a suction filter and continue to fix it on the flocked cloth in step (2) until the surface is water-free; Place it under a fluorescent lamp for 24 hours to cure and store it in a 4°C refrigerator for standby.

[0057] Example 3 Preparation of Oriented Embedded Microbial Membrane

[0058] 1. Preparation of Flocked Cloth

[0059] (1) Glue spraying: Uniformly spray polyurethane flocking glue on the knitted cloth;

[0060] (2) Electrostatic coating and flocking: Suspend the flocked fabric substrate after applying the binder in an electrostatic processing equipment. Put short fibers with a diameter of 30 μm and a length of 50 mm into the hopper of the electrostatic processing equipment. Turn on the electrostatic processing equipment, adjust the voltage to 15 KV according to the operating procedures, run for 60 s, and then turn off the electrostatic processing equipment;

[0061] (3) Drying: Put the short fiber-flocked fabric after flocking into a 60 °C dryer and dry for 30 min;

[0062] (4) Removing floating fluff: Use a vacuum cleaner to remove the short fibers that are not adhered or are poorly adhered, and obtain the flocked fabric.

[0063] 2. Sludge immobilization

[0064] (1) At 25 °C, pass the aerobic activated sludge suspension with a thickness of 2 mm through a suction filter and fix it on the flocked fabric until the surface is free of water;

[0065] (2) Pass the facultative activated sludge suspension with a thickness of 2 mm through a suction filter and continue to fix it on the flocked fabric in step (1) until the surface is free of water;

[0066] (3) Pass the anaerobic activated sludge suspension with a thickness of 2 mm through a suction filter and continue to fix it on the flocked fabric in step (2) until the surface is free of water; Place it under a fluorescent lamp for 24 hours to cure and store it in a 4 °C refrigerator for standby.

[0067] Example 4 Preparation of Oriented Embedded Microbial Membrane

[0068] 1. Preparation of flocked fabric

[0069] (1) Glue spraying: Uniformly spray polyurethane flocking glue on the knitted fabric;

[0070] (2) Electrostatic coating and flocking: Suspend the flocked fabric substrate after applying the binder in an electrostatic processing equipment. Put short fibers with a diameter of 30 μm and a length of 50 mm into the hopper of the electrostatic processing equipment. Turn on the electrostatic processing equipment, adjust the voltage to 15 KV according to the operating procedures, run for 60 s, and then turn off the electrostatic processing equipment;

[0071] (3) Drying: Put the short fiber-flocked fabric after flocking into a 60 °C dryer and dry for 30 min;

[0072] (4) Removing floating fluff: Use a vacuum cleaner to remove the short fibers that are not adhered or are poorly adhered, and obtain the flocked fabric.

[0073] 2. Sludge immobilization

[0074] (1) At 25 °C, pass the aerobic activated sludge suspension with a thickness of 3 mm through a suction filter and fix it on the flocked fabric until the surface is free of water;

[0075] (2) Pass the facultative activated sludge suspension with a thickness of 3 mm through a suction filter press and continue to fix it on the flocked cloth in step (1) until the surface is free of water.

[0076] (3) Pass the anaerobic activated sludge suspension with a thickness of 3 mm through a suction filter press and continue to fix it on the flocked cloth in step (2) until the surface is free of water. Place it under a fluorescent lamp for 24 hours for curing and store it in a 4°C refrigerator for later use.

[0077] Comparative Example 1 Preparation of Flocked Cloth

[0078] (1) Glue spraying: Uniformly spray polyurethane flocking glue on the knitted cloth.

[0079] (2) Electrostatic flocking coating: Hang the flocked cloth substrate after applying the binder into the electrostatic processing equipment. Put short fibers with a diameter of 30 μm and a length of 50 mm into the hopper of the electrostatic processing equipment. Turn on the electrostatic processing equipment, adjust the voltage to 15 KV according to the operating procedures, run for 60 s, and then turn off the electrostatic processing equipment.

[0080] (3) Drying: Put the flocked short fiber - flocked cloth into a 60°C dryer and dry for 30 min.

[0081] (4) Removing floating floss: Use a vacuum cleaner to remove the short fibers that are not adhered or are poorly adhered to obtain the flocked cloth.

[0082] Application Example 1 Treating Sewage with a Membrane Aeration Bioreactor

[0083] Assemble the membranes obtained in Examples 1 - 4 or the flocked cloth obtained in Comparative Example 1 on a 1000 mL membrane aeration biofilm reactor. Use the non - assembled one as Comparative Example 2. Adopt continuous aeration without setting reflux and stirring; the operating pressure is lower than the bubble point pressure of the directionally embedded microbial membrane, and the temperature is controlled at room temperature for biological nitrification and denitrification reactions. The specific method is as follows:

[0084] Operate in a sequential batch mode with a cycle of 24 h. Perform operations such as draining and feeding water in 24 h. Drain 1000 mL each time and feed 975 mL of water. Add 10 mL of simulated sewage concentrate (ammonia nitrogen concentration is 5 g / L, COD concentration is 30 g / L) at the beginning of each cycle. Continuously operate for 50 days. Take samples before draining water every day to test the removal effects of ammonia nitrogen and COD. Observe the morphological changes of the directionally embedded microbial membrane after 50 days.

[0085] Table 1 Film - hanging Time of Each Example and Comparative Example

[0086]

[0087] Table 1 and Figure 2-4Data analysis shows that the sewage treatment performance of the directionally embedded microbial film of the present invention has been significantly improved. The film hanging time of the examples loaded with the directionally embedded microbial film (Examples 1-4) was shortened to 3 days, while the film hanging time of the bubble-free aeration membrane without the directionally embedded microbial film (Comparative Example 2) was as long as 40 days.

[0088] The ammonia nitrogen, total nitrogen, and COD removal rates in Example 1 were higher than those in the other groups. Compared with Comparative Example 2, the ammonia nitrogen removal rate increased by more than 8%, the total nitrogen removal rate increased by more than 8%, and the COD removal rate increased by more than 6%.

[0089] The ammonia nitrogen, total nitrogen, and COD removal rates in Example 1 and Example 3 were significantly higher than those in the other treatment groups. Example 1 had an additional outermost hydrogel layer compared with Example 3. After 40 days of experimental operation, the ammonia nitrogen and total nitrogen treatment effects in Example 3 began to decline because the directionally embedded activated sludge biofilm began to fall off. This shows that the hydrogel layer played a good fixing role and did not affect the mass transfer process.

[0090] Examples 2, 3, and 4 were respectively directionally embedded with activated sludge biofilms of different thicknesses. From the data analysis, Example 2 with a thickness of 2 mm had the best effect on removing ammonia nitrogen, total nitrogen, and COD.

[0091] In Comparative Example 1, the flocked cloth did not directionally embed the activated sludge biofilm, but its villous structure provided a good attachment point for the growth of microorganisms, and the film hanging was completed on the 20th day.

Claims

1. A preparation method for a rapidly starting and directionally embedded microbial membrane for a membrane aeration bioreactor, characterized in that, It includes the following steps: (1) Spray the binder onto the flocked fabric substrate, then fix the short fibers on the flocked fabric substrate by electrostatic flocking. After curing, remove the suspended short fibers to obtain the flocked fabric; (2) Fix aerobic activated sludge, facultative activated sludge, and anaerobic activated sludge on the surface of the flocked fabric in sequence; (3) Add a photosensitizer to the polyvinyl alcohol aqueous solution to obtain a hydrogel prepolymer solution, and then place it on the surface of the flocked fabric in step (2) and carry out photocuring.

2. The preparation method according to claim 1, characterized in that, The binder is selected from polyurethane flocking glue or acrylate flocking glue; The flocked fabric substrate is non-woven fabric or knitted fabric; The material of the short fibers is one or more of polyester fiber, polyvinyl alcohol fiber, polyamide fiber, polyacrylonitrile fiber, polypropylene fiber, and polyvinyl chloride fiber; 3. The preparation method according to claim 1, characterized in that, The diameter of the short fibers is 20 - 50 μm, and the length is 30 - 100 mm; The thickness of the aerobic activated sludge, facultative activated sludge, or anaerobic activated sludge on the flocked fabric is 1 - 5 mm respectively; 4. The preparation method according to claim 1, characterized in that, The diameter of the short fibers is 30 μm, and the length is 50 mm; The thickness of the aerobic activated sludge, facultative activated sludge, or anaerobic activated sludge on the flocked fabric is 2 mm respectively; 5. The preparation method according to claim 1, characterized in that, The photosensitizer is one or two of N-methyl-4-(p-formylstyryl)pyridinium methyl sulfate, 3-methoxydiphenylamine-4-diazonium salt, and 4-diazodiphenylamine hydrogen sulfate; 6. The preparation method according to claim 1, wherein, The degree of hydrolysis of the polyvinyl alcohol is 88%; 7. The preparation method according to claim 1, characterized in that, The mass ratio of the photosensitizer to polyvinyl alcohol is 0.1 - 1:100; The mass ratio of polyvinyl alcohol to water is 10 - 15:85 - 90.

8. A rapidly-starting and directionally-embedded microbial membrane prepared by the method according to any one of claims 1 - 7.

9. Use of the rapidly-starting directionally-embedded microbial film as described in claim 8 in sewage treatment, characterized in that, It includes the following steps: Assemble the rapidly-starting and directionally-embedded microbial membrane on a membrane aeration bioreactor for aeration, carry out a biological reaction under appropriate pressure and temperature, and denitrify the sewage.

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