Hydrophobic VOCs degradation and removal device and treatment method based on membrane aeration bio-membrane reactor

Abstract

The invention relates to a hydrophobic VOCs degradation and removal device based on a membrane aeration bio-membrane reactor and a treatment method, the hydrophobic VOCs degradation and removal device comprises a main reactor, an air supply system and a liquid circulation system, hollow fiber membrane filaments are arranged in the main reactor, strains are inoculated on the hollow fiber membrane filaments and then cultured for a period of time, and the hollow fiber membrane filaments and the hollow fiber membrane filaments are separated to form the hydrophobic VOCs degradation and removal device based on the membrane aeration bio-membrane reactor. The hydrophobic VOCs degrading and removing device based on the membrane aeration bio-membrane reactor is formed, the hydrophobic VOCs degrading and removing device can be used for treating VOCs, and waste gas containing the VOCs is treated through the adsorption and degradation effects of microorganisms. The invention designs a novel non-immersed integrated MABR system mainly aiming at the problem that the existing biological treatment technology is not strong in hydrophobic VOCs removal capability, and improves the hydrophobic VOCs removal capability.

Description

Technical Field

[0001] The present invention belongs to the technical field of volatile organic compound treatment, and in particular relates to a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor and a treatment method. Background Art

[0002] Volatile organic compounds (VOCs) generally refer to organic compounds with a saturated vapor pressure greater than or equal to 0.01Mpa at 20°C, a low boiling point, and a small molecular weight. They include methane, non-methane hydrocarbon compounds, organic matter containing elements such as O, S, and N, and halogenated hydrocarbons. Common organic compounds include BTEX (benzene, toluene, ethylbenzene, and xylene), terpenoids (limonene, etc.), non-methane hydrocarbons such as n-hexane, ketones and lipids with good water solubility, etc. VOCs have the characteristics of wide sources, strong harm, difficulty in detection, long release cycle, easy local space accumulation, and long pollution impact time, which can cause great harm to both the environment and human health itself. Accidental or short-term exposure to high concentrations of VOCs may irritate the eyes, nose, throat, and lungs, and damage the liver, kidneys, and central nervous system. Even at very low concentrations, long-term exposure may cause asthma, decreased lung function, cardiovascular disease, and serious cancer.

[0003] Among the mainstream VOCs treatment technologies, biotechnology is recognized as the most efficient, low-cost and environmentally friendly technology for treating low-concentration, high-volume VOCs. Traditional biological filtration technology mainly uses bacteria to degrade hydrophilic gas phase pollutants, which are first dissolved in the liquid nutrient solution and then in contact with the biofilm on the surface of the filler. They are then adsorbed and metabolized by bacteria and converted into carbon dioxide, water and new biofilm. The key process that affects the efficiency of pollutant removal is the transfer of pollutants from the gas phase to the liquid phase. However, the mass transfer rate limitation from the gas phase to the liquid phase of hydrophobicity has seriously restricted the promotion and application of biotechnology in the field of hydrophobic treatment. Therefore, how to reduce the mass transfer resistance between the gas and liquid of VOCs in the biological treatment system and make water conducive to the growth of microorganisms without reducing the mass transfer rate of VOCs and oxygen to the biological phase is one of the key issues that need to be solved in the biological treatment of hydrophobic VOCs. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a hydrophobic VOCs degradation and removal device and treatment method based on a membrane aeration biofilm reactor.

[0005] The technical solution adopted by the present invention is: a hydrophobic VOCs degradation and removal device, comprising:

[0006] The main reactor comprises a shell, an end cover, and a hollow fiber membrane. Two end covers are arranged at both ends of the shell. The hollow fiber membrane is connected to the two end covers. The hollow fiber membrane and the two end covers form a gas passage independent of the inner cavity of the shell. The side wall of the shell is provided with four pipe openings.

[0007] A gas supply system, connected to an end cap, capable of ventilating the gas passage; or, capable of simultaneously connecting to one of the pipe ports;

[0008] A liquid circulation system connecting two or more pipes.

[0009] Preferably, a porous baffle frame is further provided in the main reactor, the porous baffle frame is fixedly arranged on the inner wall of the shell, and the hollow fiber membrane passes through the supporting holes on the porous baffle frame;

[0010] Preferably, the porous baffle frames include multiple ones, and the shapes of the porous baffle frames arranged at both ends of the main reactor are consistent with the cross-sectional shape of the shell; the multiple porous baffle frames arranged in the middle are provided with gaps; and the supporting holes through which the hollow fiber membranes pass are filled with silica gel.

[0011] Preferably, the notches on adjacent porous partition frames with notches are arranged axially symmetrically.

[0012] Preferably, an air storage cavity and a vent hole are provided in the end cover, and the hollow fiber membrane is connected to the air storage cavities of the end covers at both ends.

[0013] Preferably, the four pipe openings are respectively the first pipe opening, the second pipe opening, the third pipe opening and the fourth pipe opening, the first pipe opening and the second pipe opening are arranged on the same side, and the third pipe opening and the fourth pipe opening are arranged on the opposite sides; the first pipe opening is arranged above the second pipe opening, the third pipe opening is higher than the first pipe opening, and the fourth pipe opening is lower than the second pipe opening.

[0014] Preferably, the gas supply system includes an air compressor and a gas connecting pipeline, and a flow meter is provided on the gas connecting pipeline; one gas pipeline is connected to an end cap; another gas pipeline is connected to the second pipe port, and the third pipe port is used for gas outlet;

[0015] The liquid circulation system comprises a circulation pump and a liquid communication pipeline, and the liquid communication pipeline connects the first pipe port and the fourth pipe port.

[0016] Preferably, the gas supply system includes an air compressor and a gas connecting pipeline, and a flow meter is provided on the gas connecting pipeline; the gas pipeline is connected to an end cap;

[0017] The liquid circulation system comprises a circulation pump and a liquid connecting pipeline, one liquid connecting pipeline connects the third pipe opening and the fourth pipe opening, and the other liquid connecting pipeline connects the first pipe opening and the second pipe opening.

[0018] Preferably, a biofilm is attached to the outside of the hollow fiber membrane;

[0019] Preferably, the biofilm includes bacteria capable of adsorbing and degrading VOCs.

[0020] A method for preparing a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor, using the hydrophobic VOCs degradation and removal device, inoculating and culturing bacteria on hollow fiber membrane fibers, and forming a biofilm on the hollow fiber membrane fibers that can adsorb and degrade VOCs.

[0021] Preferably, the specific culture method is as follows:

[0022] Step 1: Inoculate the bacteria onto the hollow fiber membrane, continuously introduce air into the hollow fiber membrane through the air supply system, circulate the culture medium through the liquid circulation system, and culture for 3-5 days;

[0023] Step 2: Add the target VOCs to the culture solution, and cultivate the bacterial community on the hollow fiber membrane by gradient cultivation for 10-12 days;

[0024] Step 3: Drain all the culture solution in the main reactor, circulate the nutrient solution through one outlet, and introduce the target VOCs through another outlet, and continue culturing until a stable biofilm survival system is formed on the hollow fiber membrane.

[0025] A method for treating VOCs-containing gas by using a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor; using the hydrophobic VOCs degradation and removal device, air is continuously introduced into hollow fiber membrane threads through an air supply system; a liquid circulation system is connected to two pipe openings, nutrient solution is circulated to the main reactor, and VOCs-containing gas to be treated is introduced into the main reactor through a pipeline connected to another pipe opening of the air supply system, VOCs are adsorbed and degraded under the action of the biofilm, and the treated gas is discharged through a pipe opening.

[0026] The advantages and positive effects of the present invention are: providing a new type of non-submerged integrated MABR system to improve the removal capacity of hydrophobic VOCs; the design of the porous baffle enhances the turbulence in the main reactor and prevents the aggregation of biofilms attached to the hollow fiber membranes, thereby increasing the air-membrane contact area in the main reactor and further improving the treatment efficiency of VOCs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart of the VOCs treatment device based on MABR in Example 3 of the present invention during operation;

[0028] Figure 2 This is a process flow chart of sludge domestication of a VOCs treatment device based on MABR in Example 2 of the present invention;

[0029] Figure 3A schematic diagram of a main reactor and a circular partition plate thereof according to an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of mass transfer occurring on a hollow fiber membrane in one embodiment of the present invention;

[0031] In the figure: 1. main reactor, 11. shell, 12. hollow fiber membrane, 13. partition frame, 131. support hole, 14. end air inlet, 15. end air outlet, 16. first pipe opening, 17. second pipe opening, 18. third pipe opening, 19. fourth pipe opening, 2. air supply system, 21. air compressor, 22. washing bottle, 23. flow meter, 24. mixing bottle, 25. pressure gauge, 3. liquid circulation system, 31. nutrient solution feed bottle, 32. sprinkler, 4. VOC detector, 5. circulation pump, 6. peristaltic pump. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0033] The present invention relates to a hydrophobic VOCs degradation and removal device and treatment method based on a membrane aeration biofilm reactor. First, a hydrophobic VOCs degradation and removal device is constructed, and bacteria are placed in and cultured for a period of time to form a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor, which can be used for VOCs treatment. Through the adsorption and degradation of microorganisms, waste gas containing VOCs is treated. This scheme mainly aims at the problem that the current biological treatment technology has a weak ability to remove hydrophobic VOCs, and designs a new non-immersed integrated MABR system to improve the removal ability of hydrophobic VOCs.

[0034] First, a carrier capable of loading microbial strains to form a biofilm and having gas circulation and spraying functions is constructed to form a hydrophobic VOCs degradation and removal device. The hydrophobic VOCs degradation and removal device includes a main reactor 1, an air supply system 2 and a liquid circulation system 3, and the air supply system 2 and the liquid circulation system 3 are both connected to the main reactor 1. The main reactor 1 includes a shell 11, an end cover, a hollow fiber membrane 12 and a partition frame 13. End covers are respectively provided at both ends of the columnar shell 11, so that a closed space is formed inside the shell 11; both end covers are provided with gas storage cavities and vents, one end cover forms an end air inlet 14, and the other end cover forms an end air outlet 15. The hollow fiber membrane 12 is a tubular structure, including multiple gas storage cavities connected to two end caps at both ends of the hollow fiber membrane 12, an end air inlet 14, multiple hollow fiber membranes 12 and an end air outlet 15 to form a gas channel independent of the inner cavity of the shell, and oxygen is continuously introduced into the channel, thereby achieving oxygen supply to the microorganisms attached to the outer surface of the hollow fiber membrane 12. In order to stably fix the hollow fiber membrane 12, a porous partition frame 13 is also provided in the shell 11. The porous partition frame 13 is fixedly arranged on the shell 11, and a plurality of supporting holes 131 are provided on the porous partition frame 13. Each porous partition is distributed with 60-80 small holes, and the hollow fiber membrane 12 passes through the supporting holes 131. Each support hole 131 passes through 3-6 hollow fiber membranes 12. The porous partition frame 13 can not only support the hollow fiber membranes 12, but also produce a separation effect, so that multiple hollow fiber membranes 12 have more effective contact areas, and the surface of the hollow fiber membranes 12 can be more fully in contact with the circulating gas. There can be multiple porous partition frames 13, evenly arranged on the inner side of the shell 11; preferably, four porous partition frames 13 are included, the porous partition frames at the upper and lower ends are consistent with the cross-sectional shape of the shell, and are fixedly arranged at the upper and lower proximal ends of the shell, adjacent to the end caps on both sides; the two middle porous partition frames are fixedly connected to the inner wall of the shell and have at least partial notches. The notches on the two porous partition frames do not correspond, and are preferably axially symmetrical. When in use, after the hollow fiber membranes 12 pass through each porous partition frame 13, the support hole 131 is filled with silica gel, and the chambers separated by each porous partition frame are connected through the notch portions on the two middle porous partition frames. The design of the porous partition in this solution enhances the turbulence in the main reactor 1, prevents the aggregation of the biofilm attached to the hollow fiber membrane filaments, and increases the gas-membrane contact area in the main reactor.

[0035] The side wall of the housing 11 is provided with four nozzles, namely, the first nozzle 16, the second nozzle 17, the third nozzle 18 and the fourth nozzle 19. The first nozzle 16 and the second nozzle 17 are arranged on the same side, and the third nozzle 18 and the fourth nozzle 19 are arranged on the opposite side; wherein, the first nozzle 16 is higher than the second nozzle 17, the third nozzle 18 is slightly higher than the first nozzle 16, and the fourth nozzle 19 is slightly lower than the second nozzle 17. The air supply system 2 is connected to the end air inlet 14, and on the other hand, the air supply system 2 can be connected to the second nozzle 17. When in use, the second pipe opening 17 can be used as an air inlet, and the third pipe opening 18 can be used as an outlet to form gas circulation; the first pipe opening 16 can be used as a liquid inlet, and the fourth pipe opening 19 can be used as a liquid outlet, and the outside is connected to the liquid circulation system 3 to form a circulation system for the nutrient solution. In order to allow the nutrient solution to act evenly in the shell, the first pipe opening 16 can be set as a spray device, and corresponding to the notch of the porous partition frame with a notch on the upper side, so that it can act on both the hollow fiber membrane filaments on the upper side of the partition frame and the hollow fiber membrane filaments on the lower side of the partition. When constructing the microbial membrane on the surface of the hollow fiber membrane filament, the four pipe openings can be combined in pairs, respectively connected to the liquid circulation system 3 and the circulation pump 5, so that a culture environment suitable for the growth of microorganisms is formed inside the shell, and the circulation of the culture solution is realized.

[0036] The constructed hydrophobic VOCs degradation and removal device includes two states. One state is a liquid culture state set up to form a microbial membrane. After the bacteria are inoculated on the outside of the hollow fiber membrane, a uniform biofilm is formed on the outer surface of the hollow fiber membrane through uninterrupted culture, and the microorganisms are domesticated; the other state is a VOCs treatment state. The domesticated biofilm can adsorb and degrade VOCs. After the waste gas to be treated is introduced, the VOCs components therein are treated by the biofilm. In order to quantify and control the raw materials and products in the culture state and the treatment state, one or more of a gas washing bottle 22, a flow meter 23, a VOC detector 4, a barometer 25 and a gas valve can be set on the pipeline connecting the gas supply system 2 and the liquid circulation system 3 with the main reactor 1.

[0037] In some embodiments of the present invention, in order to achieve effective nutrition, the first pipe port can be set as a spray port, connected to the sprayer 32, and the nutrient solution is lifted from the feed bottle to the spray port through a circulation pump controlled by a timer, and evenly sprayed onto the biofilm through a nozzle. After the nutrient solution flows to the bottom of the reactor, it re-enters the feed bottle and is circulated. The circulation system ensures the airtightness of the reactor. Figure 4 As shown, when waste gas containing VOCs is introduced into the main reactor, it enters from the lower air inlet of the MABR main reactor, and the airflow path is controlled by the partition. It passes through the staggered membrane fibers and is utilized by the biofilm attached to the surface of the membrane fibers and finally degraded into inorganic matter. The purified gas is discharged from the upper part of the main reactor and enters the exhaust gas removal device.

[0038] After successfully constructing a biofilm that specifically adsorbs VOCs on the outside of the hollow fiber membrane, it can be used to treat waste gas containing VOCs. When in use, the hollow fiber membrane in the main reaction not only serves as a carrier of microorganisms, but also as an oxygen supplier, which can stably provide oxygen to the biofilm and can handle low oxygen concentrations in industrial gases because it does not require air to be directly mixed into certain anaerobic industrial gases to enhance their biodegradability. Therefore, the invention has the potential to treat relatively high concentrations of volatile organic compounds (VOCs), which may pose an explosion risk when directly supplied with oxygen. This unique feature also constructs a unique reverse mass transfer biofilm structure that allows microorganisms to grow for a longer period of time to treat difficult-to-degrade pollutants. The enhanced removal capacity of hydrophobic organic pollutants in the invention may be attributed to its unique mass transfer direction. Compared with previous studies on the maximum elimination capacity (ECmax) of volatile organic compounds in other biofilm reactors, taking toluene as an example, the present invention achieves a higher level of toluene bioconversion removal, with a toluene elimination capacity of 142 gm per unit volume. -3 h -1 The toluene elimination capacity per unit membrane area is 19.68 gm -2 d -1 .

[0039] The method of treating hydrophobic volatile organic compounds (VOCs) by a hydrophobic VOCs degradation and removal device may include the following steps:

[0040] Step 1) Biofilm formation: Take a mixed liquor suspended solids (MLSS) concentration of 4000 mg L -1 300mL of activated sludge was added. After removing the coarse particles in the fresh activated sludge, the reactor was filled with it and circulated (with the prepared nutrient solution). The aeration pressure was maintained at 0.05MPa and the peristaltic pump circulation speed was controlled at 80r min. -1 To reduce the shear force of the circulating water on the microbial membrane, the hydraulic retention time was controlled to 24h. After one day of circulation, the excess sludge was discharged and a considerable amount of nutrient solution was added. The process was continued and on the fourth day, all the suspended sludge in the reactor was discharged. Subsequently, a peristaltic pump was used to introduce nutrient solution mixed with liquid VOCs. The speed was controlled at 80r min -1 , use a circulation pump to maintain the nutrient circulation inside the reactor. The VOCs concentration in the nutrient solution gradually increases, and this stage lasts for 10 days until a relatively stable biofilm is formed;

[0041] Step 2) Air intake: VOCs enter from the lower air inlet of the MABR main reactor, the airflow path is controlled by the baffle, passes through the staggered membrane fibers, and is finally degraded into inorganic substances by the biofilm attached to the surface of the membrane fibers. The purified gas is discharged from the upper part of the main reactor and enters the tail gas removal device;

[0042] Step 3) Spraying: The nutrient solution is raised from the feed bottle to the spray port through a circulation pump controlled by a timer, and is evenly sprayed onto the biofilm through a nozzle. After the nutrient solution flows to the bottom of the reactor, it re-enters the feed bottle and is circulated. The circulation system ensures the airtightness of the reactor;

[0043] Step 4) Oxygen supply: During the operation of the reactor, clean air enters the membrane fibers from the gas storage head inlet of the lower membrane assembly, passes through the hollow fiber membrane to provide oxygen to the microorganisms attached to the membrane fibers, and the remaining air is discharged from the gas storage port at the top of the membrane assembly. The oxygen supply can be adjusted by the first gas valve and the second gas valve of the gas circuit.

[0044] The scheme of the present invention is described below in conjunction with the accompanying drawings, wherein the experimental methods without specific operating steps are all carried out in accordance with the corresponding product instructions, and the instruments, reagents, and consumables used in the examples can all be purchased from commercial companies unless otherwise specified.

[0045] Example 1: Hydrophobic VOCs degradation and removal device

[0046] The hydrophobic VOCs degradation and removal device comprises a main reactor 1, a gas supply system 2 and a liquid circulation system 3, and the gas supply system 2 and the liquid circulation system 3 are both connected to the main reactor 1. Figure 1 shown.

[0047] The main reactor 1 includes a shell 11, an end cap, a hollow fiber membrane 12 and a porous partition frame 13. The shell 11 is an acrylic glass tube with an inner diameter of 50 mm and a height of 500 mm. The porous partition frames 3 include four. The two at the two ends are circular and fixed or bonded to the two ends of the shell by glass beads. The two middle porous partition frames are in the shape of a circular notch and are fixed or bonded to the inner wall of the shell by glass columns. They are located at 170 mm and 340 mm of the tube height respectively. The four porous partition frames 13 divide the glass tube body into three sections. The porous partition frames 13 are each provided with a plurality of support holes 131, and the circular notch positions on the two middle porous partition frames with notches are axially symmetrical. The circular notch partition frame limits the airflow path in the main reactor, so that the hollow fiber membrane 12 has more sufficient contact with the airflow in the shell 11.

[0048] The outer diameter of the hollow fiber membrane 12 is 630 μm, the membrane wall thickness is 115 μm, and the effective surface length of the membrane is 350 mm. The number is 200, and the total effective surface area is 0.155 m 2 The specific surface area of ​​the membrane is 238.5m2 m -3 The arrangement form is single staggered, the ventilation form is through-type, and the total volume of the membrane is 25mL. The hollow fiber membrane 12 passes through the support hole 131, and 3-6 hollow fiber membranes 12 can pass through each support hole 131. 200 hollow fiber membranes 12 with a length of about 800mm pass through the whole system. After passing through the membrane, the remaining space in the support hole is filled with silica gel; all the hollow fiber membranes are bundled at both ends.

[0049] The end caps can be sealed at both ends of the shell, and an air storage cavity is provided in the end caps, and an air vent facing outward is opened. One end cap forms an end air inlet 14, and the other end cap forms an end air outlet 15. The two ends of the hollow fiber membrane 12 extend into the air storage cavity respectively, and the end air inlet 14, multiple hollow fiber membranes 12 and the end air outlet 15 form a gas channel independent of the inner cavity of the shell; such a structure allows the air flow inside the hollow fiber membrane to be separated from the shell, and the membrane becomes an independent oxygen supplier.

[0050] like Figure 3 As shown, four nozzles are provided on the side wall of the shell 11, namely, the first nozzle 16, the second nozzle 17, the third nozzle 18 and the fourth nozzle 19. The first nozzle 16 and the second nozzle 17 are arranged on the same side, and the third nozzle 18 and the fourth nozzle 19 are arranged on the opposite side; wherein, the first nozzle 16 is higher than the second nozzle 17, the third nozzle 18 is slightly higher than the first nozzle 16, and the fourth nozzle 19 is slightly lower than the second nozzle 17. Through the flexible use of the four nozzles, the formation, cultivation and use of the biological enzyme in the main reactor 1 are realized. The four nozzles can be connected to the gas supply system 2 or the liquid circulation system 3 respectively, so as to realize the purpose of conveying gas or culture liquid in the main reactor 1. Among them, the first nozzle 16 is located at the gap of the air partition with a gap on the upper side.

[0051] The gas supply system 2 includes an air compressor 21 and a gas connecting pipeline. A plurality of flow meters 23 are arranged on the gas connecting pipeline to calculate the gas delivery amount. A gas pipeline connected to the air compressor 21 is connected to the end air inlet 14 to continuously deliver air or oxygen to the hollow fiber membrane 12 to provide an oxygen environment for the biological enzyme adsorbed thereon, and the excess gas will be discharged through the end air outlet 15. Another gas connecting management can be connected from the air compressor 21 as needed to deliver gas to the shell 11 through one of the four pipe openings. A washing bottle 22 can be provided in the connecting passage between the air compressor 21 and the shell 11 to deliver different types of domesticated gas or gas samples to be tested into the shell. When the delivered gas is a mixture of multiple types of gases, a mixing bottle 24 can be added downstream of the washing bottle 22. The liquid circulation system 3 includes a circulation pump and a liquid connecting pipeline. The liquid connecting pipeline can form a circulation passage with the main reactor 1 through the pipe opening to realize the supply circulation of the culture liquid of the biological bacteria.

[0052] When the first pipe opening 16 is a spray opening, the liquid circulation system 3 further includes a sprayer 32 .

[0053] Example 2: Construction of a hydrophobic VOCs degradation and removal device based on a membrane aerated biofilm reactor

[0054] The hydrophobic VOCs degradation and removal device constructed in Example 1 is connected to the gas supply system and the liquid circulation system, and the bacteria are inoculated in the main reactor 1 to form a biofilm. Figure 2 As shown, the air compressor 21 is connected to the air inlet 14 through the gas communication pipeline, and the gas communication pipeline is also provided with a barometer 25 and an air valve to control the amount of air or oxygen introduced; air is transported to the hollow fiber membrane through the gas path. The first pipe opening 16 is used as an outlet, and the second pipe opening 17 is used as an inlet. The first pipe opening 16 and the second pipe opening 17 are connected by a liquid communication pipeline, and a circulation pump 5 is also provided between the first pipe opening 16 and the second pipe opening 17; the fourth pipe opening 19 is used as an outlet, and the third pipe opening 18 is used as an inlet. The third pipe opening and the fourth pipe groove are connected by a liquid communication pipeline. A nutrient solution feeding bottle 31 and a peristaltic pump 6 are provided in sequence between the fourth pipe opening and the third pipe opening. The nutrient solution feeding bottle 31 is used to carry the culture solution, which can be used to recycle the used culture solution and provide new culture solution at the same time. The nutrient solution feeding bottle 31, the peristaltic pump 6, the main reactor 1, the circulation pump 5, and the main reactor 1 form a circulation system, so that the nutrient solution in the main reactor 1 is dynamically circulated and supplied to ensure the growth environment of the bacterial flora.

[0055] When constructing the biofilm, the activated sludge from the aeration tank of the sewage treatment plant was used as the inoculated bacteria, and the MLSS was 4000 mg L -1 300mL of fresh activated sludge was added. After removing the coarse particles in the fresh activated sludge, the reactor was filled with it and the prepared nutrient solution was circulated. The aeration pressure was maintained at 0.05MPa and the peristaltic pump circulation speed was controlled at 80r min. -1 To reduce the shear force of the circulating water flow on the microbial membrane, the hydraulic retention time is controlled to 24 hours. After one day of circulation, the excess sludge is discharged and an equivalent amount of nutrient solution is added. The process is continued and all the suspended sludge in the reactor is discharged on the fourth day.

[0056] The target VOCs were added to the culture solution, and the bacterial community on the hollow fiber membrane was domesticated and cultured by gradient domestication. Then a peristaltic pump was used to pass the nutrient solution mixed with liquid VOCs, and the speed was controlled at 80 rmin. -1 , use a circulation pump to maintain the internal nutrient circulation of the reactor. In this example, toluene is used as an example to represent the treatment of VOCs. 5-40 μL of toluene (5, 10, 15, 20, 25, 30, 35, 40) is gradually added to 2L of nutrient solution, and the nutrient solution mixed with toluene is passed through a peristaltic pump, and the speed is controlled at 80rmin -1, a circulation pump was used to maintain nutrient circulation inside the reactor. The toluene concentration in the nutrient solution was gradually increased. This stage lasted for 10 days.

[0057] Drain all the culture solution in the main reactor and switch to spraying acclimation. Change the connection mode of the four nozzles; the fourth nozzle 19 is connected to the nutrient solution feed bottle 31, and then connected to the first nozzle 16 via the sprayer 32. The sprayer 32 with a timing function can spray the nutrient solution into the main reactor 1 in a timely and quantitative manner, so that the bacterial community attached to the hollow fiber membrane filaments 12 can be supplied with nutrients. The accumulated nutrient solution is collected at the lower part of the shell, discharged from the fourth nozzle 19, and re-enters the feed bottle. The air compressor 21 is also provided with an air delivery channel, which is connected to the second nozzle 17 to introduce VOC gas into the main reactor 1, thereby realizing the acclimation of the biofilm flora.

[0058] The concentration of the solution was about 200 mg L -1 The VOC gas was directly domesticated and sprayed with nutrient solution at regular intervals to proliferate the microorganisms on the hollow fiber membrane. The spraying frequency was 30 seconds every 10 minutes, and the spraying volume was 3.12L d -1 . Add 0.5g of anhydrous glucose (C 6 H 12 O 6 ), 1g KH 2 PO 4 , 1g K 2 HPO 4 , 1g NH 4 Cl, 1g NaCl, 0.02g MgSO 4 and 0.02 g CaCl 2 Spraying and acclimatization are carried out until the microorganisms form a relatively stable living system on the outer surface of the membrane fibers, completing the biofilm formation.

[0059] In order to detect the state of the microbial film, a switchable detection opening may be provided on the shell to sample and detect the biofilm, thereby determining the state of the biofilm. It is worth noting that after sampling, the detection opening must be closed and sealed with a sealant.

[0060] Example 3: Hydrophobic VOCs degradation and removal treatment method

[0061] A hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor prepared in Example 2 is used. A liquid toluene washing bottle and a pure water washing bottle are arranged upstream of the first pipe opening 16. The liquid toluene washing bottle and the pure water washing bottle are ventilated respectively by an air compressor. A flow meter 23 is arranged upstream of the liquid toluene washing bottle and the pure water washing bottle for statistics. A mixing bottle 24 is arranged downstream of the liquid toluene washing bottle and the pure water washing bottle. The gas passing through the liquid toluene washing bottle and the pure water washing bottle is mixed in the mixing bottle. The toluene waste gas and the clean air enter and exit in the same direction to form simulated toluene waste gas. The second pipe opening 17 is connected downstream of the mixing bottle 24. A flow meter 23 and an online VOCs detector 4 are arranged between the mixing bottle and the second pipe opening 17.

[0062] By regulating the gas flow rate on each path, the treatment process of the simulated VOC gas in the main detector is adjusted. The simulated VOC gas enters the main reactor 1 from the first pipe port 16, passes through a specific treatment gas path, and is discharged from the third pipe port 18. An online VOCs detector 4 is set downstream of the third pipe port 18 to evaluate the treatment efficiency of the treatment device.

[0063] During the test, simulated toluene waste gas enters from the lower part of the HMABR reactor, passes through the staggered membrane fibers, and is finally degraded into inorganic matter by the biofilm attached to the surface of the membrane fibers. The purified gas is discharged from the upper part of the main reactor 1. It was found that under the conditions of room temperature 25°C and atmospheric pressure 101Kpa, the concentration of toluene can be controlled within the range of 0-4000mg m -3 The HMABR gas empty bed residence time varies within a certain range, and the HMABR gas empty bed residence time is 120s-30s. It was operated continuously for 30 days under this condition. The treatment efficiency was tested when the empty bed residence time was 120s, 60s, and 30s, and the average removal efficiency of toluene was 91.7%, 73.4%, and 59.4%, respectively. The maximum removal capacity of toluene was 142.0gm -3 h -1 It can be seen that the device can effectively achieve the efficient removal of toluene in toluene waste gas.

[0064] This example uses toluene as an example to illustrate the adsorption treatment process of VOCs in this device and proves its adsorption treatment effect. Similarly, this device can not only be used for the adsorption and removal of toluene, but also for other types of VOCs. Other types of VOCs are used in the domestication process to domesticate the biofilm on the surface of the membrane fiber.

[0065] Example 4: Mixed VOCs degradation and removal treatment method

[0066] The device of the present invention can also be used for the removal of various types of mixed VOCs. This embodiment takes a mixed gas of toluene and acetone as an example to illustrate the mixed VOCs degradation and removal process.

[0067] like Figure 1 As shown, a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor prepared in Example 2 is used. A liquid toluene washing bottle, a liquid acetone washing bottle and a pure water washing bottle are arranged upstream of the first pipe opening 16. The liquid toluene washing bottle, the liquid acetone washing bottle and the pure water washing bottle are ventilated respectively by an air compressor 21. A flow meter is arranged upstream of the liquid toluene washing bottle, the liquid acetone washing bottle and the pure water washing bottle for statistics; a mixing bottle 24 is arranged downstream of the liquid toluene washing bottle, the liquid acetone washing bottle and the pure water washing bottle, and the gases passing through the liquid toluene washing bottle, the liquid acetone washing bottle and the pure water washing bottle are mixed in the mixing bottle, and the toluene and acetone mixed exhaust gas and the clean air enter and exit in the same direction to form a simulated mixed exhaust gas. The second pipe opening 17 is connected downstream of the mixing bottle 24, and a flow meter 23 and an online VOCs detector 4 are arranged between the mixing bottle and the second pipe opening 17.

[0068] By regulating the gas flow rate on each path, the treatment process of the simulated VOC gas in the main detector is adjusted. The simulated VOC gas enters the main reactor 1 from the second pipe port 17, passes through a specific treatment gas path, and is discharged from the third pipe port 18. An online VOCs detector 4 is set downstream of the third pipe port 18 to evaluate the treatment efficiency of the treatment device.

[0069] During the test, the simulated mixed exhaust gas enters from the bottom of the HMABR reactor, passes through the staggered membrane fibers, and is finally degraded into inorganic substances by the biofilm attached to the surface of the membrane fibers. The purified gas is discharged from the top of the main reactor. It was found that under the conditions of room temperature of 25°C and atmospheric pressure of 101Kpa, the total concentration of toluene and acetone mixed gas was controlled at 0-4000mg m -3 The HMABR gas empty bed residence time varies within a certain range, and the HMABR gas empty bed residence time is 120s-20s. It was operated continuously for 30 days under this condition. The treatment efficiency was tested when the empty bed residence time was 120s, 60s, 30s, and 20s, and the overall average removal efficiency of the mixed gas was 92.3%, 95.7%, 60.8%, and 64.0%, respectively. The maximum removal capacity of the mixed gas of toluene and acetone was 253.8gm -3 h -1 The average removal efficiency of toluene was 91.6%, 93.6%, 63.3%, and 57.4%, respectively. The maximum removal capacity of toluene was 212.1 gm -3 h -1 The average removal efficiency of acetone is 93.1%, 87.8%, 67.9% and 39.0% respectively. It can be seen that the device can effectively achieve efficient removal of organic pollutants in mixed VOCs gas.

[0070] Similarly, when the device is used to remove other types of mixed VOCs gases, the mixed gas is also used to domesticate the biofilm on the surface of the membrane fibers, thereby obtaining a reactor for removing mixed VOCs gases.

[0071] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A hydrophobic VOCs degradation and removal device, characterized by: include, The main reactor comprises a shell, an end cover, and a hollow fiber membrane. Two end covers are arranged at two ends of the shell. The hollow fiber membrane communicates with the two end covers. The hollow fiber membrane and the two end covers form a gas passage independent of the inner cavity of the shell. The side wall of the shell is provided with four pipe openings. A gas supply system, connected to one of the end caps, capable of ventilating the gas passage; or capable of simultaneously connecting to one of the pipe ports; A liquid circulation system is connected to two or more of the pipe openings.

2. A hydrophobic VOCs degradation and removal device according to claim 1, characterized in that: A porous baffle frame is also provided in the main reactor, and the porous baffle frame is fixedly arranged on the inner wall of the shell, and the hollow fiber membrane passes through the supporting holes on the porous baffle frame; Preferably, the porous baffle frames include multiple ones, and the shapes of the porous baffle frames arranged at both ends of the main reactor are consistent with the cross-sectional shape of the shell; the multiple porous baffle frames arranged in the middle are provided with gaps; and the supporting holes through which the hollow fiber membrane filaments pass are filled with silica gel. Preferably, the notches on adjacent porous partition frames having notches are arranged axially symmetrically.

3. A hydrophobic VOCs degradation and removal device according to claim 1, characterized in that: The end cover is provided with the air storage cavity and ventilation holes, and the hollow fiber membrane is connected to the air storage cavities of the end covers at both ends.

4. The hydrophobic VOCs degradation and removal device according to claim 1, characterized in that: The four pipe openings are respectively a first pipe opening, a second pipe opening, a third pipe opening and a fourth pipe opening, wherein the first pipe opening and the second pipe opening are arranged on the same side, and the third pipe opening and the fourth pipe opening are arranged on the opposite side; the first pipe opening is arranged above the second pipe opening, the third pipe opening is higher than the first pipe opening, and the fourth pipe opening is lower than the second pipe opening.

5. A hydrophobic VOCs degradation and removal device according to claim 4, characterized in that: The gas supply system includes an air compressor and a gas connecting pipeline, wherein a flow meter is provided on the gas connecting pipeline; one of the gas pipelines is connected to one of the end caps; another of the gas pipelines is connected to the second pipe port, and the third pipe port is used for gas outlet; The liquid circulation system comprises a circulation pump and a liquid communication pipeline, wherein the liquid communication pipeline connects the first pipe port and the fourth pipe port.

6. A hydrophobic VOCs degradation and removal device according to claim 4, characterized in that: The gas supply system includes an air compressor and a gas connecting pipeline, wherein a flow meter is provided on the gas connecting pipeline; the gas pipeline is connected to one of the end caps; The liquid circulation system comprises a circulation pump and a liquid communication pipeline, one of the liquid communication pipelines connects the third pipe port and the fourth pipe port, and the other of the liquid communication pipelines connects the first pipe port and the second pipe port.

7. A hydrophobic VOCs degradation and removal device according to any one of claims 1 to 5, characterized in that: A biofilm is attached to the outer side of the hollow fiber membrane; Preferably, the biofilm includes bacteria capable of adsorbing and degrading VOCs.

8. A method for preparing a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor, characterized in that: Using the hydrophobic VOCs degradation and removal device described in any one of claims 1 to 7, after inoculating and culturing bacteria on the hollow fiber membrane, a biofilm capable of adsorbing and degrading VOCs is formed on the hollow fiber membrane.

9. The method for preparing a hydrophobic VOCs degradation and removal device based on a membrane aerated biofilm reactor according to claim 8, characterized in that: The specific cultivation methods are as follows: Step 1: Inoculate the bacteria onto the hollow fiber membrane, continuously introduce air into the hollow fiber membrane through the air supply system, circulate the culture medium through the liquid circulation system, and culture for 3-5 days; Step 2: Add the target VOCs to the culture solution, and cultivate the bacterial community on the hollow fiber membrane by gradient cultivation for 10-12 days; Step 3: Drain all the culture solution in the main reactor, circulate the nutrient solution through one outlet, and introduce the target VOCs through another outlet, and continue culturing until a stable biofilm survival system is formed on the hollow fiber membrane.

10. A method for treating VOCs-containing gas using a hydrophobic VOCs degradation and removal device based on a membrane aeration biofilm reactor; characterized in that: The hydrophobic VOCs degradation and removal device as described in claim 7 is used, and air is continuously introduced into the hollow fiber membrane filaments through the air supply system; the liquid circulation system is connected to the two pipe openings, and nutrient solution is circulated to the main reactor, and the VOCs-containing gas to be treated is introduced into the main reactor through a pipeline connected to another pipe opening of the air supply system, and VOCs are adsorbed and degraded under the action of the biofilm, and the treated gas is discharged through a pipe opening.

Images