Air-lift loop cross-flow membrane biological sewage treatment device and its treatment method

Abstract

The present invention relates to the technical field of sewage treatment, and particularly to an air-lift circulation cross-flow membrane sewage biological treatment device and a treatment method thereof. The treatment device includes: a reaction tank, a membrane system, two aeration devices, and a raw water tank. An opening is provided at the top of the reaction tank, and an installation area is provided below the opening; the membrane system is installed in the installation area, dividing the reaction tank into a first area and a second area; two membrane modules 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 cause an opposite circulation flow pattern to be formed in the first area and the second area; the raw water tank is communicated with the first area and the second area respectively through two water pipes, and a first peristaltic pump is arranged on each water pipe. The advantages of the present invention are that the purposes of removing organic matter, nitrogen, and phosphorus and membrane filtration separation are simultaneously achieved in one reaction tank, forming an air-lift circulation cross-flow membrane integrated urban sewage biological treatment process.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to an air-lift circulation cross-flow membrane sewage biological treatment device and a treatment method thereof. Background Art

[0002] As a new and efficient sewage treatment technology, the membrane bioreactor (MBR) has increasingly attracted the attention of researchers in various countries. Compared with traditional biological treatment technologies, the MBR process has the advantages of good effluent quality, direct reusability, small floor area, convenient automation control, high activated sludge concentration, and low excess sludge production. With the maturity of membrane technology and the reduction of costs, the MBR technology has been widely used in sewage treatment at home and abroad.

[0003] Under high standards and strict requirements, a batch of improved processes and combined processes have emerged to meet the high-standard treatment requirements of urban sewage. However, most of these processes still mainly rely on traditional nitrogen and phosphorus removal processes, and mainly improve the performance of the biological treatment section by improving traditional processes or combining with other processes. Among them, based on the advantages of the MBR process, combining processes such as A2O (Anaerobic-Anoxic-Oxic) and oxidation ditch with it, and using the superimposed advantages of the combined process to improve the sewage biological treatment effect has become a commonly used method.

[0004] However, in the process of nitrogen and phosphorus removal in the urban sewage treatment process based on the MBR process combination, it is either necessary to form different oxygen biochemical environments spatially in two or more independent structures, or to form different oxygen biochemical environments temporally in the same structure. On the one hand, this design has problems such as long process flow, large floor area, complex regulation, and high investment and operation costs. On the other hand, although the addition of MBR in the combined process improves the treatment effect, it also brings the most prominent problems of high energy consumption and membrane fouling of MBR. Summary of the Invention

[0005] In view of this, the present invention aims to provide an air-lift circulation cross-flow membrane sewage biological treatment device and a treatment method thereof. The aeration device generates an air-lift circulation flow pattern inside the reaction tank, thereby forming different oxygen biochemical reaction environments existing simultaneously in the same space, and coupling with the membrane system to realize an integrated sewage biological treatment device. At the same time, the sewage biological treatment device cleverly uses the circulation flow pattern generated by aeration to generate a circulation cross-flow on the surface of the membrane system, thereby weakening the influence of the concentration polarization of the mixed liquid on the membrane surface on membrane fouling.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: An air-lift circulating cross-flow membrane sewage biological treatment device, comprising: a reaction tank, an opening is provided at the top of the reaction tank, and an installation area is provided below the opening; a membrane system, the membrane system is installed in the installation area, dividing 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 form an opposed circulation flow pattern in the first area and the second area; a raw water tank, 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.

[0007] Further, a baffle is provided at the opening; flow guiding plates are respectively provided in the first area and the second area, and the flow guiding plates are close to the opening.

[0008] Further, the membrane system includes a time relay and at least two membrane modules, as well as an electronic pressure gauge and a second peristaltic pump equal in number to the membrane modules; the two membrane modules are vertically arranged along the height direction of the reaction tank; the high-pressure end of the electronic pressure gauge is connected to one membrane module, 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.

[0009] Further, 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.

[0010] Further, it further includes a dissolved oxygen monitoring device, and the dissolved oxygen monitoring device determines the aeration volume of the aeration device according to the anaerobic state, anoxic state and aerobic state in different intervals in the first area and the second area.

[0011] An air-lift circulating cross-flow membrane sewage biological treatment method, realized by using the above-mentioned air-lift circulating cross-flow membrane sewage biological treatment device, comprises the following steps:

[0012] S1: Sewage is conveyed 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 pipes.

[0013] S2: Use two aeration devices and utilize the baffle and flow guiding plates of the reaction tank to form an opposed 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, anoxic zone and aerobic zone, and at the same time, the membrane modules of the membrane system are flushed;

[0014] S3: The treated sewage is discharged from the reaction tank after being filtered by the membrane system.

[0015] Furthermore, in step S2, the organic matter in the sewage is hydrolyzed and acidified in the anaerobic zone and coupled with the denitrification reaction in the anoxic zone for metabolism.

[0016] Furthermore, in step S2, the organic matter is oxidized and decomposed into carbon dioxide and water in the aerobic zone.

[0017] Furthermore, in step S2, the aeration device generates a circulating flow pattern through aeration, forming a circulating cross-flow on the surface of the membrane system; among them, the membrane modules located below are scoured by the circulating water flow, and the membrane modules located above are scoured by the bubbles generated by the aeration device; through these two scouring methods, the concentration polarization phenomenon of the mixed liquor on the surface of the membrane module is effectively weakened, thereby reducing the impact of membrane fouling.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0019] 1) Through the top plate, the baffle plate and the aeration device of the reaction tank, two opposing circulating flow patterns are formed in the first area and the second area of the reaction tank.

[0020] 2) Based on the flow field characteristics and mass transfer characteristics, the aeration intensity of the aeration device is reasonably controlled to achieve the simultaneous existence of anaerobic, anoxic and aerobic biochemical reaction environments in the same area.

[0021] 3) The membrane system is fixed in the reaction tank. The membrane modules located below are scoured by the circulating water flow, and the membrane modules located above are scoured by the bubbles generated by the aeration device; through these two scouring methods, the concentration polarization phenomenon of the mixed liquor on the surface of the membrane module is effectively weakened, and the membrane fouling rate is greatly slowed down while saving energy consumption.

[0022] 4) Under the condition of continuous flow operation, the present invention realizes the purpose of simultaneously removing organic matter, nitrogen and phosphorus and membrane filtration separation in a reaction tank, forming an air-lift type circulating cross-flow membrane integrated urban sewage biological treatment process.

[0023] 5) The two opposing circulating flow patterns enable the simultaneous existence of anaerobic-anoxic-aerobic in-situ degradation biochemical reaction processes inside the reaction tank, realizing various nitrogen and phosphorus removal pathways such as synchronous nitrification and denitrification, shortcut nitrification and denitrification, and denitrifying phosphorus removal, improving the efficiency of the biochemical tank and reducing the demand for carbon source and oxygen.

[0024] 6) Effectively utilize the driving force of the aeration bubbles flowing and the function of the baffle plate to provide power for the circulation of the sewage, and rely on the characteristics of the circulating flow field to realize the synchronous removal of pollutants under different oxygen environments. At the same time, the travel of the aeration bubbles inside the reaction tank is greatly extended, and the inside of the reaction tank is in a slightly pressurized state, greatly improving the oxygen utilization rate and reducing the operation energy consumption of the device.

[0025] 7) The advantages of the MBR process are fully exploited through the membrane system, which features a high activated sludge concentration and a low yield of surplus activated sludge.

[0026] 8) The floor area is saved by 30%, the construction cost is reduced by 10%, and the comprehensive energy consumption during operation is reduced by more than 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0028] Figure 1 is a schematic structural diagram of an air-lift circulation cross-flow membrane sewage biological treatment device provided according to an embodiment of the present invention.

[0029] The reference numerals include: 1, reaction tank; 11, bottom plate; 12, enclosing plate; 13, top plate; 14, vertical plate; 15, deflector plate; 2, membrane system; 21, membrane module; 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 device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0031] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 should not be construed as a limitation to 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 specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0034] The present invention will be described in detail below with reference to embodiments.

[0035] As Figure 1 shown, an air-lift circulating cross-flow membrane sewage biological treatment device provided by an embodiment of the present invention includes: 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, dividing 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 make the first area and the second area form an opposing circulation flow pattern. The raw water tank 4 is communicated with the first area and the second area respectively through two water pipes 5, and a first peristaltic pump 6 is arranged on each water pipe 5. Sewage enters the reaction tank 1 from the raw water tank 4 through the first peristaltic pump 6 via the water pipes 5 at the center points of the first area and the second area of the reaction tank 1. The dissolved oxygen monitoring device 7 is used to detect the anaerobic state in the anaerobic zone, the anoxic state in the anoxic zone, and the aerobic state in the aerobic zone in the first area and the second area. According to the monitoring results, the aeration volume of the aeration device 3 is controlled in combination with the gas flow meter 32.

[0036] The reaction tank 1 includes a bottom plate 11, four enclosing plates 12, a top plate 13, and four vertical plates 14. The bottom plate 11, the four enclosing plates 12, and the top plate 13 jointly enclose a rectangular cavity with an opening at the top. The opening is provided at the middle position 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, making the reaction tank 1 in a non-closed state and using the vertical plates 14 to raise the water level. Since the bubbles generated by the aeration device 3 cannot quickly overflow through the opening, the air-water ratio relatively increases, thus maintaining a slightly pressurized state inside the reaction tank 1.

[0037] Flow guiding plates 15 are respectively arranged in the first area and the second area, and the flow guiding plates 15 are close to the opening. The flow guiding plates 15 are arranged obliquely to optimize the air flow distribution. The top plate 13, the flow guiding plates 15, and the aeration device 3 of the reaction tank 1 form two counter-directional circulating flow patterns in the first area and the second area of the reaction tank 1.

[0038] Specifically, the four enclosing plates 12 enclose 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. There is an opening in the middle of the top plate 13, dividing the top plate 13 into a two-piece structure. The height of the vertical plate 14 is determined according to the liquid level height and the protection height of the reaction tank 1. The protection height refers to the safety height to prevent liquid overflow or external pollutants from entering the reaction tank 1.

[0039] The traditional A2O (anaerobic - anoxic - aerobic) process is usually composed of three tank bodies in series: A (anaerobic), A (anoxic), and O (aerobic). According to the design requirements of the "Technical Specification for Anaerobic - Anoxic - Aerobic Activated Sludge Process Sewage Treatment Engineering" (HJ 576 - 2010), the volume ratio of the three tank bodies is 1 - 2: 2 - 4: 8 - 12. This invention omits two A tanks. Therefore, the floor area is relatively saved by 30%, and the construction cost is reduced by 10%. In the traditional A2O process, a reflux system from the O tank to the second A (anoxic) tank needs to be set up, and a stirring system needs to be set up in each of the two A tanks respectively. This invention omits the reflux system and the stirring system. In addition, since the travel of the aeration bubbles in water in this invention is extended, the oxygen utilization rate is improved, and thus the aeration energy consumption is saved. Therefore, the comprehensive energy-saving effect of the operation of this invention can reach more than 20%.

[0040] The membrane system 2 includes a time relay 24 and at least two membrane modules 21, as well as an electronic pressure gauge 22 and a second peristaltic pump 23 with the same number as the membrane modules 21. The two membrane modules 21 are vertically arranged along the height direction of the reaction tank 1 and are located below the opening. The membrane modules 21 are connected to the second peristaltic pump 23 through pipelines, and the electronic pressure gauge 22 is located between the membrane modules 21 and the second peristaltic pump 23. The second peristaltic pump 23 is electrically connected to the time relay 24.

[0041] Under the suction of the second peristaltic pump 23, the sewage is filtered through the pore spaces on the membrane surface of the membrane module 21, and the clear water passing through the membrane flows out along the pipeline between the membrane system 2 and the second peristaltic pump 23. To slow down the pollution 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 a time relay 24. The function of the second peristaltic pump 23 is to provide power for the sewage to pass through the pore spaces on the membrane surface of the membrane module 21.

[0042] The electronic pressure gauge 22 installed on the pipeline monitors the degree of membrane pollution. Through the pressure change of the electronic pressure gauge 22, when the transmembrane pressure difference is generally greater than 0.05 MPa (the transmembrane pressure difference of different brands will be larger), membrane cleaning is required.

[0043] 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, near the intersection of the bottom plate 11 and the enclosing plate 12, and away from the membrane system 2. The other aerator 31 is arranged at the bottom of the second area, near the intersection of the bottom plate 11 and the enclosing plate 12, and away from the membrane system 2.

[0044] 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 an opposing circulation flow pattern in the first area and the second area of the reaction tank 1.

[0045] The dissolved oxygen monitoring device 7 is used to detect the anaerobic state in the anaerobic zones, the hypoxic state in the hypoxic zones, and the aerobic state in the aerobic zones in the first area and the second area.

[0046] The aeration device 3 not only provides oxygen for the microorganisms in the reaction tank 1, but also is the power source for forming a good circulation flow pattern inside the reaction tank 1 and improving the oxygen mass transfer efficiency. The size of the aeration intensity directly affects the flow pattern inside the reaction tank 1 and the oxygen transfer efficiency. If the aeration volume is too small, a circulation flow pattern cannot be formed, while if the aeration volume is too large, the sewage in the central area will be excessively agitated. Therefore, an appropriate aeration volume should ensure that the sewage in the outer circle circulates at a stable flow rate, and at the same time make the sewage circulation flow rate from the aerobic zone to the anaerobic zone decrease in a gradient, and finally remain relatively static in the central area. This flow characteristic not only promotes the sewage circulation, but also significantly enhances the mass transfer efficiency of oxygen into the solution.

[0047] The experiment numerically simulated the sewage flow pattern in reaction tank 1 under different aeration rates. According to the test monitoring results, when the aeration rate 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 circulating flow pattern can be formed inside 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, then adjust the gas flowmeter 32 to reduce the aeration rate of the aeration device 3. If the dissolved oxygen in the aerobic zone is lower than 0.5 mg / L, then adjust the gas flowmeter 32 to increase the aeration rate of the aeration device 3.

[0048] An air-lift circulating cross-flow membrane sewage biological treatment method, realized by using the above-mentioned air-lift circulating cross-flow membrane sewage biological treatment device, includes the following steps:

[0049] S1: Put the inoculated activated sludge into reaction tank 1. The sewage is transported from the raw water tank 4 to the first area and the second area of reaction tank 1 through the water pipe 5 by the first peristaltic pump 6. The inoculated activated sludge and the sewage form a biochemical system with co-existing multiple functional bacterial communities in the sewage biological treatment device.

[0050] Specifically, put the activated sludge inoculated from the aeration tank of the sewage treatment plant into reaction tank 1. Under the conditions that the average MLSS (Mixed Liquor Suspended Solids) in reaction tank 1 is about 5000 mg / L, the HRT (Hydraulic Retention Time) and SRT (Solids Retention Time) are 14 h and 20 d respectively, the influent is continuously fed, and the effluent is operated continuously in an operation mode with a discharge cycle of pumping for 8 minutes and stopping for 2 minutes. After 10 - 15 days of domestication, the effluent water quality indexes of the system are stable, and the indexes of COD (Chemical Oxygen Demand), TN (Total Nitrogen), and TP (Total Phosphorus) all reach the first-class A standard of the "Pollutant Discharge Standard for Municipal Wastewater Treatment Plants" GB18918 - 2002. The domestication of the activated sludge in the sewage biological treatment device is completed, and a biochemical system with co-existing multiple functional bacterial communities is formed.

[0051] S2: Use two aeration devices 3 and utilize the baffle 14 and the guide plate 15 to form an opposite circulating flow pattern in the first area and the second area, so that the organic matter, nitrogen and phosphorus pollutants in the sewage circulate between the anaerobic zone, the anoxic zone and the aerobic zone, thereby realizing in-situ metabolism and decomposition. At the same time, this circulating flow pattern can also scour the membrane system 2 and slow down membrane fouling.

[0052] Specifically, the aeration device 3 generates a circulating flow pattern through aeration, forming a circulating cross-flow on the surface of the membrane system 2. Among them, the membrane system 21 located below is scoured by the circulating water flow, and the membrane system 21 located above is scoured by the bubbles generated by the aeration device 3. Through these two scouring methods, the concentration polarization phenomenon of the mixed liquor on the surface of the membrane system 21 is effectively weakened, thereby reducing the influence of membrane fouling.

[0053] The dissolved oxygen content in the activated sludge sewage mixed solution in the reaction tank 1 is supplied by the aeration device 3. Under the pushing of 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 pattern. In the outer circle of the circulating flow, due to a large amount 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 pattern and mass transfer properties, the oxygen molecules in the outer circle of the circulating flow will transfer to the inner circle, but the transfer ability is limited. Therefore, a region with a 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 towards the center of the reaction tank 1, due to the lack of oxygen supply and the limited oxygen mass transfer ability of the outer circle, the dissolved oxygen in the central region is below 0.2 mg / L, thus forming an anaerobic zone in the central region.

[0054] 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 area, and metabolized into carbon sources and small molecule organic matters that can be efficiently utilized by polyphosphate-accumulating bacteria and denitrifying bacteria. At the same time, in this area, the polyphosphate-accumulating bacteria use small molecule organic matters to complete carbon source energy storage; the products nitrate nitrogen and nitrite nitrogen after nitrification reaction in the outer aerobic area return to the anaerobic and anoxic areas through mass diffusion and transfer, and under the condition of fully utilizing carbon sources and ammonia nitrogen, various biological nitrogen and phosphorus removal mechanisms such as denitrification, simultaneous nitrification and denitrification, shortcut nitrification and denitrification, anaerobic ammonium oxidation, autotrophic denitrification, and denitrifying phosphorus removal are completed, saving carbon sources and energy consumption.

[0055] Polysaccharide hydrolysis: (C6H 10 O5)n + nH2O nC6H 12 O6;

[0056] Glucose to acetic acid: C6H 12 O6 3CH3COOH.

[0057] Carbon source storage: VFAs (volatile fatty acids) + ATP PHA + CO2

[0058] Denitrification: NO3 − + 5[H] 0.5N2+2OH − +H2O

[0059] Simultaneous nitrification and denitrification: NH4 + +O2 N2+H2O;

[0060] Short-cut nitrification and denitrification: NH4 + +1.5O2+3CH3COOH→N2+6CO2+8H2O+2H + ;

[0061] Anaerobic ammonium oxidation: NH4 + +NO2 - N2+H2O;

[0062] Denitrifying phosphorus removal: NO3 − +PO4 3− +organic matter N2+Poly-P (polyphosphate).

[0063] In the aerobic zone, the unutilized carbon source organic matter is finally oxidized and decomposed into carbon dioxide and water in this area; at the same time, ammonification, nitritation, nitrification reactions and aerobic phosphorus uptake by polyphosphate-accumulating organisms occur in this area. At this time, there is basically no problem of competition between heterotrophic bacteria and nitrifying bacteria in the aerobic zone. Therefore, NH4 + -N can be nitrified more thoroughly.

[0064] Oxidation and decomposition of organic matter: organic matter + O2 CO2+H2O+energy+new cell material (C5H7NO2)

[0065] Ammonification: RCHNH2COOH + O2 RCOOH + CO2 + NH3;

[0066] Nitritation: NH4 + +1.5O2 NO2 − +H2O+2H + +energy

[0067] Nitrification: NH4 + +2O2 NO3 - +H2O+2H + ;

[0068] Aerobic phosphorus uptake: PHB + O2 + PO4 3- Polyphosphate (Poly-P) + CO2 + H2O + energy (ATP)

[0069] S3: The treated sewage is discharged from the reaction tank 1 after being filtered by the membrane system 2.

[0070] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within 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 form a counter-circulation flow pattern in the first area and the second area; each of the aeration devices comprises 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; A raw water tank, wherein the 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; sewage enters the reaction tank from the raw water tank through the water pipe from the center point of the first area and the center point of the second area of ​​the reaction tank through the 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: 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.

5. 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 4, 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.

6. The airlift circulating cross-flow membrane wastewater biological treatment method according to claim 5 is characterized in that: In step S2, organic matter in the sewage is hydrolyzed and acidified in the anaerobic zone and the anoxic zone.

7. The airlift circulating cross-flow membrane wastewater biological treatment method according to claim 5 is characterized in that: In step S2, the organic matter is oxidized and decomposed into carbon dioxide and water in the aerobic zone.

8. The airlift circulating cross-flow membrane wastewater biological treatment method according to claim 5 is 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.

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