Airlift type circulating cross-flow membrane sewage biological treatment device and treatment method thereof

Abstract

The invention relates to the technical field of sewage treatment, in particular to an airlift circulating cross-flow membrane biological sewage treatment device and a treatment method thereof, and the treatment device comprises a reaction tank, a membrane system, two aeration devices and a raw water tank. An opening is formed in the top of the reaction tank, and a mounting area is arranged below the opening; the membrane system is mounted in the mounting area and divides the reaction tank into a first area and a second area; two membrane assemblies of the membrane system are vertically arranged along the height direction of the reaction tank; the two aeration devices are respectively arranged in the first area and the second area; the two aeration devices enable the first area and the second area to form an opposite circulating flow state; the raw water tank is respectively communicated with the first area and the second area through two water pipes, and a first peristaltic pump is arranged on each water pipe. The device has the advantages that the purposes of removing organic matters, nitrogen and phosphorus and filtering and separating the membrane in one reaction tank at the same time are achieved, and a set of airlift circulating cross-flow membrane integrated urban sewage biological treatment process is formed.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to an airlift type circulating cross-flow membrane sewage biological treatment device and a treatment method thereof. Background Art

[0002] As a new and efficient sewage treatment technology, membrane bioreactor (MBR) has attracted increasing attention from researchers around the world. Compared with traditional biological treatment technology, MBR process has the advantages of good effluent quality, direct reuse, small footprint, easy automation control, high activated sludge concentration, and low excess sludge production. With the maturity of membrane technology and the reduction of costs, MBR technology has been widely used in sewage treatment at home and abroad.

[0004] Under the high standards and strict requirements, a number of improved processes and combined processes have been developed to meet the high-standard treatment needs of urban sewage. However, most of these processes are still based on traditional nitrogen removal and phosphorus removal processes, and the performance of the biological treatment section is improved mainly by improving traditional processes or combining with other processes. Among them, based on the advantages and characteristics of the MBR process, combining A2O (Anaerobic-Anoxic-Oxic), oxidation ditch and other processes with it, and using the advantages of the combined process to enhance the biological treatment effect of sewage has become a commonly used method.

[0005] However, in the process of nitrogen and phosphorus removal, the urban sewage treatment process based on the MBR process combination needs to either form different oxygen biochemical environments in space in two or more independent structures, or form different oxygen biochemical environments in time in the same structure. On the one hand, this design has problems such as long process flow, large floor space, complex regulation, and high investment and operation costs. On the other hand, although the combination process adds MBR to improve the treatment effect, it also brings the most prominent problems of MBR, high energy consumption and membrane pollution. Summary of the invention

[0006] In view of this, the invention aims to provide an airlift circulating cross-flow membrane sewage biological treatment device and a treatment method thereof. The aeration device generates an airlift circulating flow state inside the reaction tank, thereby forming different oxygen biochemical reaction environments coexisting in the same space, and is coupled with the membrane system to realize an integrated sewage biological treatment device. At the same time, the sewage biological treatment device cleverly utilizes the circulating flow state generated by aeration to generate a circulating cross-flow on the surface of the membrane system, thereby reducing the influence of the concentration polarization of the mixed liquid on the membrane surface on the membrane pollution.

[0007] To achieve the above-mentioned purpose, the technical solution created by the present invention is implemented as follows: an airlift circulating cross-flow membrane wastewater biological treatment device, comprising: a reaction tank, an opening is arranged at the top of the reaction tank, and an installation area is arranged below the opening; a membrane system, the membrane system is installed in the installation area, and the reaction tank is divided into a first area and a second area; two aeration devices, the two aeration devices are respectively arranged in the first area and the second area; the two aeration devices enable the first area and the second area to form a counter-circulating flow state; a raw water tank, the raw water tank is connected to the first area and the second area respectively through two water pipes, and each water pipe is provided with a first peristaltic pump.

[0008] Furthermore, a baffle is provided at the opening; guide plates are provided in the first area and the second area respectively, and the guide plates are close to the opening.

[0009] Furthermore, the membrane system includes a time relay and at least two membrane assemblies, as well as an electronic pressure gauge and a second peristaltic pump equal in number to the membrane assemblies; the two membrane assemblies are vertically arranged along the height direction of the reaction tank; the high-pressure end of the electronic pressure gauge is connected to a membrane assembly, the low-pressure end of the electronic pressure gauge is connected to the output end of the second peristaltic pump, and the second peristaltic pump is electrically connected to the time relay.

[0010] Furthermore, each aeration device includes an aerator, a gas flow meter and an air compressor; the aerator is connected to the air compressor through the gas flow meter; one of the aerators is arranged at the bottom of the first area and away from the membrane system; the other aerator is arranged at the bottom of the second area and away from the membrane system.

[0011] Furthermore, it also includes a dissolved oxygen monitoring device, which determines the aeration amount of the aeration device according to the anaerobic state, the anoxic state and the aerobic state of different intervals in the first area and the second area.

[0012] An airlift circulating cross-flow membrane wastewater biological treatment method is implemented using the above-mentioned airlift circulating cross-flow membrane wastewater biological treatment device, comprising the following steps: S1: The sewage is transported from the raw water tank to the first area and the second area of ​​the reaction tank through the first peristaltic pump via the water pipe.

[0013] S2: Use two aeration devices and utilize the baffles and guide plates of the reaction tank to form a counter-circulation flow pattern in the first area and the second area, so that the organic matter in the sewage is metabolized and decomposed between the anaerobic zone, the anoxic zone and the aerobic zone, and at the same time, the membrane components of the membrane system are flushed; S3: The treated sewage is filtered through the membrane system and then discharged from the reaction tank.

[0014] Furthermore, in step S2, organic matter in the sewage is hydrolyzed and acidified in the anaerobic zone, and is metabolized in a coupled manner with denitrification in the anoxic zone.

[0015] Furthermore, in step S2, the organic matter is oxidized and decomposed into carbon dioxide and water in the aerobic zone.

[0016] Furthermore, in step S2, the aeration device generates a circulating flow state through aeration, forming a circulating cross-flow on the surface of the membrane system; wherein the membrane components located at the bottom are flushed by the circulating water flow, and the membrane components located at the top are flushed by the bubbles generated by the aeration device; through these two flushing methods, the concentration polarization phenomenon of the mixed liquid on the surface of the membrane components is effectively weakened, thereby reducing the impact of membrane pollution.

[0017] Compared with the prior art, the invention can achieve the following beneficial effects: 1) Two opposite circulation flow patterns are formed in the first area and the second area of ​​the reaction tank through the top plate, guide plate and aeration device of the reaction tank.

[0018] 2) Based on the flow field characteristics and material transfer characteristics, the aeration intensity of the aeration device is reasonably controlled to achieve the coexistence of anaerobic, anoxic and aerobic biochemical reaction environments in the same area.

[0019] 3) The membrane system is fixed in the reaction tank. The membrane components at the bottom are flushed by the circulating water flow, and the membrane components at the top are flushed by the bubbles generated by the aeration device. Through these two flushing methods, the concentration polarization phenomenon of the mixed liquid on the surface of the membrane components is effectively weakened, which greatly slows down the membrane pollution rate while saving energy.

[0020] 4) Under continuous flow operation, the present invention achieves the purpose of simultaneously completing the removal of organic matter, nitrogen and phosphorus and membrane filtration separation in one reaction tank, forming a set of airlift circulation cross-flow membrane integrated urban sewage biological treatment process.

[0021] 5) The two opposite circulation flow patterns enable the simultaneous anaerobic-anoxic-aerobic in-situ degradation biochemical reaction process inside the reaction pool, realizing multiple nitrogen removal and phosphorus removal pathways such as simultaneous nitrification and denitrification, short-range nitrification and denitrification, and denitrification and phosphorus removal, thereby improving the efficiency of the biochemical pool and reducing the demand for carbon sources and oxygen.

[0022] 6) Effectively utilize the driving force of the aeration bubble flow and the function of the guide plate to provide power for the circulation of sewage, and use the characteristics of the circulating flow field to achieve the simultaneous removal of pollutants under different oxygen environments. At the same time, the aeration bubble travels much longer inside the reaction tank, and the reaction tank is in a micro-pressure state, which greatly improves the utilization rate of oxygen and reduces the operating energy consumption of the device.

[0023] 7) The advantages of MBR process are fully utilized through the membrane system, with the characteristics of high activated sludge concentration and low residual activated sludge production.

[0024] 8) The floor space is saved by 30%, the construction cost is reduced by 10%, and the comprehensive energy saving in operation is more than 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 It is a structural schematic diagram of an airlift circulating cross-flow membrane sewage biological treatment device provided according to an embodiment of the present invention.

[0026] The reference numerals include: 1. reaction tank; 11. bottom plate; 12. enclosure; 13. top plate; 14. vertical plate; 15. guide plate; 2. membrane system; 21. membrane assembly; 22. electronic pressure gauge; 23. second peristaltic pump; 24. time relay; 3. aeration device; 31. aerator; 32. gas flow meter; 33. air compressor; 4. raw water tank; 5. water pipe; 6. first peristaltic pump; 7. dissolved oxygen monitoring equipment. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0031] The present invention will be described in detail below with reference to the embodiments.

[0032] like Figure 1 As shown, an airlift type circulating cross-flow membrane sewage biological treatment device provided by an embodiment of the present invention comprises: a reaction tank 1, a membrane system 2, two aeration devices 3, a raw water tank 4 and a dissolved oxygen monitoring device 7. An opening is provided at the top of the reaction tank 1, and a membrane system 2 installation area is provided below the opening. The membrane system 2 is installed in the installation area to separate the reaction tank 1 into a first area and a second area. The two aeration devices 3 are respectively arranged in the first area and the second area, and the two aeration devices 3 form a counter-circulating flow state in the first area and the second area. The raw water tank 4 is connected to the first area and the second area respectively through two water pipes 5, and each water pipe 5 is provided with a first peristaltic pump 6. The sewage enters the reaction tank 1 from the center point of the first area and the center point of the second area of ​​the reaction tank 1 through the first peristaltic pump 6 from the raw water tank 4 through the water pipe 5. The dissolved oxygen monitoring device 7 is used to detect the anaerobic state of the anaerobic zone, the anoxic state of the anoxic zone and the aerobic state of the aerobic zone in the first area and the second area. According to the monitoring results, the aeration amount of the aeration device 3 is controlled in combination with the gas flow meter 32.

[0033] The reaction tank 1 includes a bottom plate 11, four surrounding plates 12, a top plate 13 and four vertical plates 14. The bottom plate 11, the four surrounding plates 12 and the top plate 13 together enclose a rectangular cavity with an opening at the top. The opening is arranged in the middle of the top plate 13. The four vertical plates 14 are vertically arranged on the top plate 13 and are located at the edges of the four sides of the opening, so that the reaction tank 1 forms a non-closed state, and the vertical plates 14 are used to raise the water level. Since the bubbles generated by the aeration device 3 cannot overflow quickly through the opening, the air-water ratio is relatively increased, so that the inside of the reaction tank 1 maintains a micro-pressure state.

[0034] The first area and the second area are provided with guide plates 15 respectively, and the guide plates 15 are close to the openings and arranged obliquely to optimize the airflow distribution. The top plate 13, the guide plates 15 and the aeration device 3 of the reaction tank 1 form two opposite circulation flow patterns in the first area and the second area of ​​the reaction tank 1.

[0035] Specifically, four enclosures 12 form a rectangular cylinder, and the bottom plate 11 is connected to the bottom of the rectangular cylinder. The top plate 13 is connected to the top of the rectangular cylinder, and an opening is provided in the middle of the top plate 13, dividing the top plate 13 into a two-half structure. The height of the vertical plate 14 is determined according to the liquid level of the reaction tank 1 and the protection height. The protection height refers to a safe height to prevent liquid from overflowing or external contaminants from entering the reaction tank 1.

[0036] The traditional A2O (anaerobic-anoxic-aerobic) process is usually composed of three tanks A (anaerobic), A (anoxic), and O (aerobic) connected in series. According to the design requirements of the "Technical Specifications for Anaerobic-Anoxic-Aerobic Activated Sludge Wastewater Treatment Engineering" (HJ 576-2010), the volume ratio of the three tanks is 1~2:2~4:8~12. The present invention eliminates two A tanks, so the floor space is relatively saved by 30% and the construction cost is reduced by 10%. In the traditional A2O process, it is necessary to set up a reflux system from the O tank to the second A (anoxic) tank, and to set up a stirring system in the two A tanks respectively. The present invention eliminates the reflux system and the stirring system. In addition, since the travel of the aeration bubbles in the water in the present invention is extended, the oxygen utilization rate is improved, thereby saving aeration energy consumption. Therefore, the comprehensive energy-saving effect of the operation of the present invention can reach more than 20%.

[0037] The membrane system 2 includes a time relay 24 and at least two membrane assemblies 21, as well as an electronic pressure gauge 22 and a second peristaltic pump 23 equal to the number of membrane assemblies 21. The two membrane assemblies 21 are arranged vertically along the height direction of the reaction tank 1 and are located below the opening. The membrane assembly 21 is connected to the second peristaltic pump 23 through a pipeline, and the electronic pressure gauge 22 is located between the membrane assembly 21 and the second peristaltic pump 23. The second peristaltic pump 23 is electrically connected to the time relay 24.

[0038] Under the suction action of the second peristaltic pump 23, the sewage is filtered through the pores on the membrane surface of the membrane assembly 21, and the clean water that permeates the membrane flows out along the pipeline between the membrane system 2 and the second peristaltic pump 23. In order to reduce the contamination of the membrane system 2 and facilitate physical cleaning, the second peristaltic pump 23 adopts an intermittent operation mode (running for 8 minutes and stopping for 2 minutes), and its start and stop are controlled by the time relay 24. The function of the second peristaltic pump 23 is to provide power for the sewage to pass through the pores on the membrane surface of the membrane assembly 21.

[0039] The electronic pressure gauge 22 installed on the pipeline monitors the degree of membrane contamination. Through the pressure change of the electronic pressure gauge 22, when the trans-membrane pressure difference is generally greater than 0.05MPa (the trans-membrane pressure difference of different brands will be larger), the membrane needs to be cleaned.

[0040] Each aeration device 3 includes an aerator 31, a gas flow meter 32 and an air compressor 33. The aerator 31 is connected to the air compressor 33 through the gas flow meter 32. One of the aerators 31 is arranged at the bottom of the first area, close to the junction of the bottom plate 11 and the enclosure 12, and away from the membrane system 2. The other aerator 31 is arranged at the bottom of the second area, close to the junction of the bottom plate 11 and the enclosure 12, and away from the membrane system 2.

[0041] The compressed air generated by the air compressor 33 enters the aerator 31 through the gas flow meter 32 . The bubbles released by the two aerators 31 drive the water body to flow during the rising process, forming a counter-circulation flow state in the first area and the second area of ​​the reaction tank 1 .

[0042] The dissolved oxygen monitoring device 7 is used to detect the anaerobic state of the anaerobic zone, the anoxic state of the anoxic zone, and the aerobic state of the aerobic zone in the first zone and the second zone.

[0043] The aeration device 3 not only provides oxygen for the microorganisms in the reaction tank 1, but also serves as a power source for forming a good circulation flow state inside the reaction tank 1 and improving the oxygen mass transfer efficiency. The aeration intensity directly affects the flow state and oxygen transfer efficiency inside the reaction tank 1. If the aeration amount is too small, a circulation flow state cannot be formed, and if the aeration amount is too large, the sewage in the central area will be excessively agitated. Therefore, the appropriate aeration amount should ensure that the outer circle sewage circulates at a stable flow rate, while making the sewage circulation flow rate from the aerobic zone to the anaerobic zone decrease gradually, and finally maintain a relatively static state in the central area. This flow characteristic not only promotes sewage circulation, but also significantly enhances the mass transfer efficiency of oxygen into the solution.

[0044] The experiment numerically simulated the flow state of sewage in the reaction tank 1 under different aeration conditions. According to the test monitoring results, when the aeration amount of the aeration device 3 keeps the dissolved oxygen in the anaerobic zone below 0.2 mg / L, the dissolved oxygen in the anoxic zone between 0.2 and 0.5 mg / L, and the dissolved oxygen in the aerobic zone above 0.5 mg / L, a good circulation flow state can be formed inside the reaction tank 1, and a high oxygen mass transfer efficiency can be maintained. If the dissolved oxygen in the anaerobic zone exceeds 0.2 mg / L or the dissolved oxygen in the anoxic zone is higher than 0.5 mg / L, the gas flow meter 32 is adjusted to reduce the aeration amount of the aeration device 3. If the dissolved oxygen in the aerobic zone is lower than 0.5 mg / L, the gas flow meter 32 is adjusted to increase the aeration amount of the aeration device 3.

[0045] An airlift circulating cross-flow membrane wastewater biological treatment method is implemented using the above-mentioned airlift circulating cross-flow membrane wastewater biological treatment device, comprising the following steps: S1: The inoculated activated sludge is put into the reaction tank 1, and the sewage is transported from the raw water tank 4 to the first area and the second area of ​​the reaction tank 1 through the first peristaltic pump 6 and the water pipe 5. The inoculated activated sludge and sewage form a biochemical system with coexistence of multiple functional bacteria in the sewage biological treatment device.

[0046] Specifically, the activated sludge inoculated from the aeration tank of the sewage treatment plant was put into the reaction tank 1, and the average MLSS (Mixed Liquor Suspended Solids) in the reaction tank 1 was controlled to be about 5000 mg / L. Under the conditions that the HRT (Hydraulic Retention Time) and SRT (Solids Retention Time) were 14 h and 20 d respectively, the inlet was continuously inlet, and the effluent was continuously operated in an operation mode of pumping for 8 min and stopping for 2 min as one effluent cycle. After 10-15 days of acclimation, the effluent water quality indicators of the system were stable, and the COD (Chemical Oxygen Demand), TN (Total Nitrogen) and TP (Total Phosphorus) indicators all reached the Level A standard of "Pollutant Discharge Standard for Urban Sewage Treatment Plants" GB18918-2002. The activated sludge in the sewage biological treatment device was domesticated, and a biochemical system with coexistence of multiple functional bacteria was formed.

[0047] S2: Use two aeration devices 3 and use baffles 14 and guide plates 15 to form a counter-circulation flow pattern in the first area and the second area, so that organic matter and nitrogen and phosphorus pollutants in the sewage circulate between the anaerobic zone, the anoxic zone and the aerobic zone, thereby achieving in-situ metabolism and decomposition. At the same time, the circulation flow pattern can also flush the membrane system 2 and reduce membrane pollution.

[0048] Specifically, the aeration device 3 generates a circulating flow state through aeration, forming a circulating cross flow on the surface of the membrane system 2; wherein the membrane system 21 located below is flushed by the circulating water flow, and the membrane system 21 located above is flushed by the bubbles generated by the aeration device 3; through these two flushing methods, the concentration polarization phenomenon of the mixed liquid on the surface of the membrane system 21 is effectively weakened, thereby reducing the impact of membrane pollution.

[0049] The dissolved oxygen content in the activated sludge sewage mixed solution in the reaction tank 1 is supplied by the aeration device 3. Driven by the bubbles released by the aeration device 3 and the drainage effect of the vertical plate 14, the activated sludge sewage mixed solution in the reaction tank 1 forms a circulating flow state. In the outer circle of the circulating flow, due to the large number of bubbles doped in the activated sludge sewage mixed solution, the dissolved oxygen concentration is higher than 0.5 mg / L, so this area belongs to the aerobic area. Due to the circulating flow state and the nature of material transfer, the oxygen molecules in the outer circle of the circulating flow will be transferred to the inner circle, but the transfer capacity is limited. Therefore, a region with dissolved oxygen between 0.2 and 0.5 mg / L will be formed near the outer circle, which is called the anoxic zone. Further expanding to the center of the reaction tank 1, due to the lack of oxygen supply and the limited oxygen mass transfer capacity of the outer circle, the dissolved oxygen in the central area is below 0.2 mg / L, thus forming an anaerobic zone in the central area.

[0050] In the anaerobic and anoxic zones, the sewage transported from the raw water tank 4 to the reaction tank 1 is mixed with the activated sludge, and the organic matter in the sewage is hydrolyzed and acidified in this zone, and metabolized into carbon sources and small molecular organic matter that can be efficiently utilized by polyphosphate bacteria and denitrifying bacteria. At the same time, polyphosphate bacteria in this zone use small molecular organic matter to complete carbon source energy storage; the nitrate nitrogen and nitrite nitrogen products of the nitrification reaction in the peripheral aerobic zone are returned to the anaerobic and anoxic zones through the diffusion and transfer of substances, and under the condition of making full use of carbon sources and ammonia nitrogen, a variety of biological denitrification and phosphorus removal mechanisms such as denitrification, simultaneous nitrification and denitrification, short-range nitrification and denitrification, anaerobic ammonia oxidation, autotrophic denitrification and denitrification phosphorus removal are completed, saving carbon sources and energy consumption.

[0051] Polysaccharide hydrolysis: (C6H 10 O5)n+nH2O nC 12 O6; Glucose produces acetic acid: C6H 12 O6 3CH3COOH.

[0052] Carbon source storage: VFAs (volatile fatty acids) + ATP PHA+CO2 Denitrification: NO3 − +5[H] 0.5N2+2OH − +H2O Simultaneous nitrification and denitrification: NH4 + +O2 N2+H2O; Short-term nitrification and denitrification: NH4 + +1.5O2+3CH3COOH→N2+6CO2+8H2O+2H + ; Anaerobic ammonium oxidation: NH4 ++NO2 - N2+H2O; Denitrification and phosphorus removal: NO3 − +PO4 3− +Organic Matter N2+Poly-P (polyphosphate).

[0053] In the aerobic zone, the unused carbon source organic matter is finally oxidized and decomposed into carbon dioxide and water; at the same time, ammoniation, nitrite, nitrification and aerobic phosphorus absorption by polyphosphate bacteria occur in this area. At this time, there is basically no problem of competition between heterotrophic bacteria and nitrifying bacteria in the aerobic zone, so NH4 + -N can be nitrified more thoroughly.

[0054] Oxidative decomposition of organic matter: organic matter + O2 CO2+H2O+energy+new cell material (C5H7NO2) Amination: RCHNH2COOH+O2 RCOOH+CO2+NH3; Nitrosation: NH4 + +1.5O2 NO2 − +H2O+2H + +Energy Nitrification: NH4 + +2O2 NO3 - +H2O+2H + ; Aerobic phosphorus absorption: PHB+O2+PO4 3- Polyphosphate (Poly-P) + CO2 + H2O + energy (ATP) S3: The treated sewage is filtered through the membrane system 2 and then discharged from the reaction tank 1.

[0055] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An airlift circulating cross-flow membrane wastewater biological treatment device, characterized in that: include: A reaction tank, wherein the top of the reaction tank is provided with an opening, and a mounting area is provided below the opening; A membrane system, wherein the membrane system is installed in the installation area and separates the reaction tank into a first area and a second area; Two aeration devices, the two aeration devices are respectively arranged in the first area and the second area; the two aeration devices enable the first area and the second area to form a counter-circulation flow state; A raw water tank is connected to the first area and the second area respectively through two water pipes, and each of the water pipes is provided with a first peristaltic pump.

2. The airlift circulating cross-flow membrane wastewater biological treatment device according to claim 1 is characterized in that: A baffle is arranged at the opening; guide plates are respectively arranged in the first area and the second area, and the guide plates are close to the opening.

3. The airlift circulating cross-flow membrane wastewater biological treatment device according to claim 1 is characterized in that: The membrane system comprises a time relay and at least two membrane assemblies, and an electronic pressure gauge and a second peristaltic pump equal in number to the membrane assemblies; The two membrane modules are arranged vertically along the height direction of the reaction tank; The high-pressure end of the electronic pressure gauge is connected to one of the membrane components, the low-pressure end of the electronic pressure gauge is connected to the output end of the second peristaltic pump, and the second peristaltic pump is electrically connected to the time relay.

4. The airlift circulating cross-flow membrane wastewater biological treatment device according to claim 1 is characterized in that: Each of the aeration devices includes an aerator, a gas flow meter and an air compressor; the aerator is connected to the air compressor through the gas flow meter; one of the aerators is arranged at the bottom of the first area and away from the membrane system; the other aerator is arranged at the bottom of the second area and away from the membrane system.

5. The airlift circulating cross-flow membrane wastewater biological treatment device according to claim 1 is characterized in that: It also includes a dissolved oxygen monitoring device, which determines the aeration amount of the aeration device according to the anaerobic state of the anaerobic zone, the anoxic state of the anoxic zone, and the aerobic state of the aerobic zone in the first zone and the second zone.

6. An airlift circulating cross-flow membrane wastewater biological treatment method, implemented by using the airlift circulating cross-flow membrane wastewater biological treatment device according to any one of claims 1 to 5, characterized in that: The steps include: S1: The inoculated activated sludge is put into the reaction tank, and the sewage is transported from the raw water tank to the first area and the second area of ​​the reaction tank through the first peristaltic pump and the water pipe, and the inoculated activated sludge and sewage form a biochemical system with coexistence of multiple functional bacteria in the sewage biological treatment device; S2: using two of the aeration devices and utilizing the baffles and guide plates of the reaction tank to form a counter-circulation flow pattern in the first area and the second area, so that organic matter in the sewage is metabolized and decomposed between the anaerobic zone, the anoxic zone and the aerobic zone, and at the same time, the membrane components of the membrane system are flushed; S3: The treated sewage is filtered through the membrane system and then discharged from the reaction tank.

7. The airlift circulating cross-flow membrane wastewater biological treatment method according to claim 6 is characterized in that: In step S2, organic matter in the sewage is hydrolyzed and acidified in the anaerobic zone and the anoxic zone.

8. The airlift circulating cross-flow membrane wastewater biological treatment method according to claim 6 is characterized in that: In step S2, the organic matter is oxidized and decomposed into carbon dioxide and water in the aerobic zone.

9. The airlift circulating cross-flow membrane wastewater biological treatment method according to claim 6, characterized in that: In step S2, the aeration device generates a circulating flow state through aeration, forming a circulating cross flow on the surface of the membrane system; wherein the membrane components located at the bottom are flushed by the circulating water flow, and the membrane components located at the top are flushed by the bubbles generated by the aeration device; through these two flushing methods, the concentration polarization phenomenon of the mixed liquid on the surface of the membrane components is effectively weakened, thereby reducing the impact of membrane pollution.

Images