A self-circulating sewage treatment device and method for sludge expansion bed coupled with MBR

Abstract

The present invention's self-circulating sewage treatment device, combining an expanded sludge bed and an MBR, includes a reactor body, a raw water tank, an outlet water tank, a water distribution device, a rectifier, an aeration head, a fan, an overflow weir, a return line, and a PLC control box. It is characterized in that a membrane separation zone is formed above the aeration zone, in which an MBR membrane assembly is installed, allowing the sewage to circulate and be purified under the action of aeration. The present invention's method for treating low- and medium-concentration urban wastewater includes: a) inoculating sludge; b) starting the system; c) influent and anaerobic reaction; d) aeration, aerobic reaction, and return flow; e) sewage rectification; f) effluent and return flow; and g) backwashing. The present invention's circulating sewage treatment device and method do not require additional power from a circulating pump, have improved shock load resistance, and can be flexibly adjusted to suit different influent water qualities, such as for treating high-concentration industrial wastewater alone or low- and medium-concentration urban wastewater without the addition of an external carbon source.

Description

Technical Field

[0001] The present invention relates to a sewage treatment device and method, and more particularly to a self-circulating sewage treatment device and method of a sludge expansion bed coupled with an MBR. Background Art

[0002] Currently, the activated sludge process is a commonly used wastewater treatment process. Its ease of operation and widespread adoption make it the preferred method for many wastewater treatment plants. However, despite its relative operational simplicity, the activated sludge process has limited adaptability to water quality fluctuations, particularly under conditions of fluctuating water quality and high water loads. Aeration is ineffective in this process, and high water loads often require significant aeration to meet discharge standards, leading to significant energy consumption and increased operating costs.

[0003] Expanded sludge bed technology, as an improved version of the activated sludge process, has significant advantages in treating high-concentration industrial wastewater and low-concentration urban sewage. Sewage enters the reactor evenly through the water distribution device at the bottom of the reactor, flows from bottom to top through the sludge bed at a certain flow rate, and the effluent is recirculated into the reactor through external equipment. At the bottom of the reactor, there is a high-concentration, highly active sludge bed with a high hydraulic load. However, existing expanded sludge bed technology still faces some challenges. Uneven water distribution can easily create dead zones and poor mass transfer effects. When the inlet water quality fluctuates, the separation effect will be affected, resulting in problems such as suspended matter in the effluent.

[0004] Membrane bioreactor technology has brought new possibilities to wastewater treatment. Membrane bioreactors achieve efficient solid-liquid separation through membrane filtration, retaining high sludge concentrations within the reactor, effectively improving the efficiency of the biochemical reaction and achieving better effluent quality. This technology can further enhance the solid-liquid separation efficiency of the expanded sludge bed, trapping more sludge within the reactor. However, membrane modules in membrane bioreactors are prone to clogging, requiring frequent aeration and flushing, which undoubtedly increases operating costs.

[0005] Combining a membrane bioreactor with an expanded sludge bed (SLB) can better retain sludge and extend its lifespan. However, existing membrane cleaning methods are complex and require more frequent chemical treatments. Therefore, while this combination retains a significant amount of sludge within the system, optimizing membrane cleaning operations, reducing operating costs, and improving overall system efficiency remain challenges that require further resolution. Summary of the Invention

[0006] In order to overcome the shortcomings of the above technical problems, the present invention provides a self-circulating sewage treatment device and method of a sludge expansion bed coupled with an MBR.

[0007] The sludge expansion bed coupled MBR self-circulating sewage treatment device of the present invention comprises a reactor body, a raw water tank, an outlet water tank, a water distribution device, a rectifier, an aeration head, a fan, an overflow weir, a return pipe and a PLC control box. The interior of the reactor body is a cavity. The water distribution device is arranged at the bottom of the cavity inside the reactor body. The raw water tank is connected to the water distribution device through an inlet pipe and an inlet water pump. The rectifier is located in the middle of the cavity inside the reactor body. A sludge expansion bed area is formed between the water distribution device and the rectifier. Granular sludge for treating sewage is inoculated in the sludge expansion bed area. The overflow weir is located at the upper part of the cavity inside the reactor body. The return pipe is connected to the MBR. The upper end is connected to the overflow weir, and the lower end is connected to the water distribution device; the reactor body is provided with DO and pH sensors, an ultrasonic level gauge and a pressure sensor, and a PLC control box controls the operation of the sewage treatment device; it is characterized in that: the aeration head is located in the middle of the internal cavity of the reactor body and above the rectifier; the fan is connected to the aeration head via a pipeline provided with a first aeration electric valve and a first rotor flowmeter, and the upper part of the aeration head forms an aeration zone; the upper part of the aeration zone forms a membrane separation zone, in which an MBR membrane assembly is provided, and the water outlet of the MBR membrane assembly is connected to the water outlet tank via a pipeline provided with a membrane water outlet electric valve and a membrane water outlet suction pump;

[0008] Under the aeration effect of the fan on the aeration area through the aeration head, the density of the water in the middle of the internal cavity of the reactor body is reduced and the pressure is lowered, so that the water in the sludge expansion bed area flows into the aeration area. The water in the aeration area flows upward with the aeration into the membrane separation area and flows into the overflow weir. The water in the overflow weir flows into the water distribution device through the return pipe and then flows into the sludge expansion bed area, realizing the circulation and purification of sewage under the action of aeration; the sewage after purification treatment is filtered by the MBR membrane module under the action of the membrane outlet suction pump and the clear water flows into the outlet tank, and the floating flocculent sludge suspended matter is retained in the reactor body.

[0009] The self-circulating sewage treatment device of the sludge expansion bed coupled with MBR of the present invention comprises an air storage tank, a backwash suction pump, a negative pressure air pump and a biogas compressor. The air storage tank is used to store biogas. An aeration and flushing device is provided below the MBR membrane assembly. The top of the reactor body is a gas-liquid separation zone. The outlet water tank is communicated with the water outlet of the MBR membrane assembly via a pipeline provided with a backwash suction pump and a backwash electric valve. The gas-liquid separation zone is communicated with the air storage tank via a pipeline provided with a negative pressure air pump. The air outlet of the fan is communicated with the aeration and flushing device via a pipeline provided with a first flushing electric valve. The air inlet of the biogas compressor is connected to the air storage tank. The air outlet of the biogas compressor is communicated with the aeration head via a pipeline provided with a second aeration electric valve and a second rotor flowmeter. The air outlet of the biogas compressor is communicated with the aeration and flushing device via a pipeline provided with a second flushing electric valve.

[0010] The present invention discloses a self-circulating sewage treatment device for a sludge expansion bed coupled with an MBR, wherein the rectifying device is composed of a horizontal plate and a conical lower convex portion arranged in the center of the horizontal plate, the two sides of the horizontal plate are rectangular cavities connecting the sludge expansion bed area and the aeration area, the horizontal plate is evenly provided with leakage holes, the conical lower convex portion is composed of inclined baffles and horizontal baffles arranged at intervals, and leakage areas are formed between adjacent inclined baffles and adjacent horizontal baffles; the angle between the inclined baffles and the horizontal direction is 45°~60°; the horizontal partition, the inclined baffles and the horizontal baffles achieve the purpose of blocking the downward-flowing water flow, and the upward-flowing water flows into the aeration area through the rectangular cavity, the leakage holes and the leakage area.

[0011] The self-circulating sewage treatment device of the sludge expansion bed coupled with MBR of the present invention comprises a water distribution device consisting of a water distribution main pipe and water distribution branches evenly arranged on both sides of the water distribution main pipe. The water distribution branches are connected to the water distribution main pipe, and the angle between the water distribution branches and the horizontal plane is 15°~30°. A plurality of downward-facing water distribution holes are evenly opened on the water distribution branches.

[0012] The invention discloses a self-circulating sewage treatment device for a sludge expansion bed coupled with an MBR. The MBR membrane component is a hollow fiber membrane or a hollow ceramic membrane. The pore size of the MBR membrane component is an ultrafiltration membrane with a range of 0.01 μm to 0.1 μm.

[0013] The sludge expansion bed coupled MBR self-circulating sewage treatment device of the present invention has a top of the overflow weir with a serrated upper edge, the highest point of the return pipe inlet is lower than the upper edge of the overflow weir, and the lowest point is higher than the bottom of the overflow weir.

[0014] The present invention relates to a self-circulating sewage treatment device for a sludge expansion bed coupled with an MBR, wherein the PLC control box is connected to DO and pH sensors, an ultrasonic liquid level meter, a pressure sensor, a first rotor flowmeter and a second electronic flowmeter via signal lines, and is connected to an inlet water pump, a membrane outlet water suction pump, a backwashing suction pump, a fan, a biogas compressor, a negative pressure air pump, a membrane outlet water electric valve, a backwashing electric valve, a first aeration electric valve, a first flushing electric valve, a second aeration electric valve and a second flushing electric valve via control lines.

[0015] The method of treating medium and low concentration urban wastewater by the self-circulating sewage treatment device of the sludge expanded bed coupled with the MBR of the present invention is characterized by being achieved by the following steps:

[0016] a). Inoculation of sludge: Inoculate granular sludge with good endogenous denitrification performance in the sludge expansion bed area at the bottom of the reactor body, and ensure that the sludge concentration is high after inoculation, and at the same time ensure that the inoculated granular sludge contains a certain proportion of glycogen-accumulating bacteria GAOs;

[0017] b) Start the system; the PLC control box controls the opening of the water inlet pump, the first aeration electric valve and the fan to allow the treated sewage in the raw water tank to enter the reactor body, and the sewage in the reactor body is aerated under the action of the fan;

[0018] c) Influent and anaerobic reaction: The untreated sewage in the raw water tank and the return sewage from the return pipe enter the sludge expansion bed area through the water distribution device at the bottom of the reactor body. Anaerobic reaction occurs under the biochemical action of anaerobic microorganisms in the granular sludge. Most nitrifying bacteria use the COD in the influent as an external carbon source to convert oxidized nitrogen into nitrogen gas for removal. At the same time, some denitrifying bacteria, glycogen-accumulating bacteria GAOs and phosphate-accumulating bacteria PAOs use polyhydroxyalkanoates (PHAs) and glycogen (Gly) stored in their cells as electron donors to carry out endogenous denitrification and denitrification.

[0019] d) Aeration, aerobic reaction and backflow: When sewage flows into the aeration zone, ammonia-oxidizing bacteria AOB and nitrite-oxidizing bacteria NOB oxidize ammonia nitrogen into nitrite nitrogen through the dissolved oxygen provided by the aeration head, maintaining the dissolved oxygen concentration at 0.5-2.0 mg / L. When the dissolved oxygen concentration is lower than 0.5 mg / L, the aeration intensity is increased, and when it is higher than 2.0 mg / L, the aeration intensity is reduced;

[0020] At the same time, during the aerobic reaction, the aeration head aerates and oxygenates the sewage in the lower layer of the aeration zone. The pressure of the aerated sewage in the lower layer decreases, and the water level rises rapidly, flowing into the overflow weir and then into the return pipe. The inlet water of the raw water tank and the return sewage in the return pipe flow to the bottom of the reactor body and pass through the sludge expansion bed area and aeration area for purification again. Under the action of the hydraulic shear force provided by aeration, the flocculent sludge with poor settling performance rises, while the sludge with good settling performance falls, forming granular sludge that falls to the sludge expansion bed area below.

[0021] e) Sewage rectification: Under the action of the horizontal baffles, inclined baffles and horizontal baffles in the rectification device, the water flow returning from the aeration zone to the sludge expansion bed zone is decelerated and energy is reduced, so that only a small amount of sewage flows downward through the rectification device, thereby causing the main flow to flow upward;

[0022] f) Effluent and return flow: The sewage flows to the top of the reactor, and most of the water flows into the return pipe through the overflow weir and returns to the bottom of the reactor body. Then, the pollutants in the sewage are further degraded through the above steps c) and d) and the pollutant content is recycled several times until the pollutant content meets the standard. A small amount of sewage flows into the membrane separation area, and the membrane effluent suction pump produces clear water that enters the effluent tank and subsequently enters the deep treatment unit. The floating flocculent sludge is intercepted by the MBR membrane assembly in the reactor body, so that the sludge concentration in the reactor body is maintained at a high level.

[0023] g) Backwashing: Regularly turn on the fan and the first flushing electric valve to deliver air to the aeration flushing device to the MBR membrane assembly. At the same time, turn on the backwash suction pump and backwash electric valve to extract a certain amount of water from the outlet water tank and reversely deliver it to the MBR membrane assembly for gas-liquid combined backwashing to enhance the backwashing effect and extend the service life of the MBR membrane assembly.

[0024] The method for treating high-concentration industrial wastewater by the self-circulating sewage treatment device of the sludge expanded bed coupled with the MBR of the present invention is characterized by being achieved by the following steps:

[0025] 1) Inoculation of sludge: Inoculate a certain amount of anaerobic granular sludge in the sludge expansion bed area at the bottom of the reactor body, and ensure that the sludge concentration is high after inoculation, and at the same time ensure that the inoculated granular sludge contains a certain proportion of acid-producing bacteria and methanogens;

[0026] 2) Start the system; the PLC control box controls the start of the water inlet pump, negative pressure air pump, second aeration electric valve and biogas compressor to allow the treated sewage in the raw water tank to enter the reactor body, and the biogas compressor aerates the sewage in the reactor body;

[0027] 3) Water inlet and anaerobic reaction: The untreated sewage in the raw water tank and the return sewage from the return pipe enter the sludge expansion bed area through the water distribution device at the bottom of the reactor body. Anaerobic digestion occurs under the biochemical action of anaerobic microorganisms in the anaerobic granular sludge. The organic matter in the sewage is first hydrolyzed and acidified into short-chain fatty acids and alcohols. Acidogenic bacteria further convert the short-chain fatty acids and alcohols into ethanol. Finally, the ethanol is used by methanogens to produce methane.

[0028] 4) Methane and sewage are charged into the circulation system. The sewage flows to the aeration zone, where the methane biogas in the gas storage tank is transported to the aeration head through the biogas compressor to aerate the sewage. Under the action of the gas generated in the aeration head and the sludge expansion bed area, the sewage pressure in the aeration and sludge expansion bed areas decreases, causing the sewage level to rise faster until it flows into the overflow weir and then into the return line. The return sewage and the influent water flow to the bottom of the reactor body, forming a circulation flow to treat the sewage.

[0029] At the same time, under the action of methane gas released by the aeration head, aeration provides hydraulic shear force, causing flocculent sludge with poor settling performance to rise and sludge with good settling performance to fall, forming granular sludge that falls to the sludge expansion bed area below. The timing and frequency of biogas compressor filling through the aeration head are determined by the DO and pH sensor and the 6 ultrasonic level meter online detection values. When the DO and pH sensors detect that the DO in the sewage is greater than 0.5mg / L or the liquid level remains below the overflow weir for a long time, the compressor is used to send biogas into the aeration head for aeration.

[0030] 5) Sewage rectification: Under the action of the horizontal baffles, inclined baffles and horizontal baffles in the rectification device, the water flow returning from the aeration area to the sludge expansion bed area is decelerated and decelerated, so that only a small amount of sewage flows downward through the rectification device, thereby making the main flow flow upward;

[0031] 6) Effluent and return flow: The sewage flows to the top of the reactor, and most of the water flows into the return pipe through the overflow weir and returns to the bottom of the reactor body. Then, the pollutants in the sewage are further degraded through the above steps 3) and 4). After multiple cycles of treatment, the pollutant content reaches the standard. A small amount of sewage flows into the membrane separation area and further undergoes anaerobic reaction with the sludge intercepted by the MBR membrane module to produce methane. The clear water obtained by the membrane outlet suction pump enters the water outlet tank, and the water in the water outlet tank subsequently enters the deep treatment unit. The gas generated by the reactor body is collected by the negative pressure air pump through the top gas-liquid separation area and sent to the gas storage tank;

[0032] 7) Backwashing: The backwashing suction pump 18 extracts a certain amount of water and sends it back to the MBR membrane assembly for backwashing. In addition, the biogas compressor is used to regularly send biogas from the gas storage tank to the aeration flushing device to backwash the membrane assembly to extend the service life of the MBR membrane assembly.

[0033] The beneficial effects of the present invention are as follows: the self-circulating sewage treatment device and method of the sludge expansion bed coupled with MBR of the present invention, the internal cavity of the reactor body is sequentially divided into the sludge expansion bed area, the aeration area and the membrane separation area from bottom to top, the lower part of the sludge expansion bed area, the lower part of the aeration area and the membrane separation area are respectively provided with a water distribution device, an aeration head and an MBR membrane assembly, under the aeration action of the aeration head, the sewage rises with the aeration, and the sewage at the upper part enters the return pipe under the action of the liquid level difference, and the sewage returned through the return pipe and the inlet water are re-distributed after the water distribution of the water distribution device The new sewage enters the reactor body for purification treatment, realizing the sewage circulation without the need for an external power source, reducing the energy consumption in the sewage treatment process, and controlling the sewage rising velocity by controlling the aeration gas flow, and then determining the circulation ratio according to the effluent water quality; at the same time, since the MBR membrane assembly is provided in the membrane separation area, the flocculent sludge suspended matter can be intercepted in the membrane separation area through the barrier of the MBR membrane assembly, making the produced water clear, and the effluent water quality is not affected by the rising velocity, and the effluent can directly enter the deep treatment stage.

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[0035] The self-circulating sewage treatment device and method of the sludge expanded bed coupled with MBR of the present invention has the following advantages:

[0036] (1) The aeration head in the middle of the device not only achieves the function of filling the system with gas, but also reduces the sewage pressure in the aeration area through aeration, causing the sewage to expand and rise rapidly, so that the sewage flows into the return pipe through the overflow weir and then circulates in the system again to improve the effluent quality. This increases the amount of circulating water and does not require additional power from the circulating pump, greatly reducing operating energy consumption and saving operating costs. At the same time, by controlling the aeration volume, it is easy to control the rising flow rate of the system sewage, and it can also effectively increase the turbulence level inside the system to avoid the continuous accumulation of sludge at the bottom and the occurrence of short-circuit, achieving the purpose of "one gas for multiple uses".

[0037] (2) The top of the device uses a membrane bioreactor (MBR) instead of a three-phase separator to achieve mud-water separation, avoiding the risk of excessive turbidity in the effluent and overcoming the problem of poor mud-water separation caused by water quality fluctuations. It has better resistance to shock loads and effectively intercepts the sludge in the system, making the system have a higher sludge concentration.

[0038] (3) When the device is in anaerobic operation, the biogas generated by the biochemical reaction in the system can be collected into the gas storage tank, and the membrane components can be aerated and flushed regularly by gas to perform combined gas-water backwashing, which can effectively alleviate the degree of membrane pollution, prevent membrane clogging, and extend the life of the system. At the same time, there is basically no need to introduce additional gas, which reduces the cost of backwashing.

[0039] (4) This device has multiple operating modes and can be flexibly adjusted according to different influent water qualities. For example, when treating high-concentration industrial wastewater alone, anaerobic granular sludge can be inoculated, and the entire system can be operated anaerobicly while generating methane energy resource gas for recycling and utilization. When treating medium and low-concentration urban sewage alone, residual sludge and anaerobic ammonia-oxidizing bacteria can be inoculated and operated anaerobicly in the lower part and aerobicly in the upper part. Carbon and nitrogen pollutants can be efficiently removed through the endogenous denitrification-anaerobic ammonia-oxidation process without adding an external carbon source. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic structural diagram of a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR according to the present invention;

[0041] Figure 2 Schematic diagram of the structure of the rectifier device in the present invention;

[0042] Figure 3 This is a flow chart of the environmental sewage treatment device of the present invention for treating low- and medium-concentration urban wastewater;

[0043] Figure 4 This is a flow chart of the environmental sewage treatment device of the present invention for treating high-concentration industrial wastewater.

[0044] In the figure: 1 reactor body, 2 sludge expansion bed area, 3 aeration area, 4 membrane separation area, 5 raw water tank, 6 water inlet pipeline, 7 water inlet pump, 8 water distribution device, 9 rectifier, 10 aeration head, 11 MBR membrane assembly, 12 aeration flushing device, 13 overflow weir, 14 return pipeline, 15 membrane outlet electric valve, 16 membrane outlet suction pump, 17 backwash electric valve, 18 backwash suction pump, 19 PLC control box, 20 gas-liquid separation area, 21 fan, 22 gas storage tank, 23 biogas compressor, 24 negative pressure air pump, 25 DO and pH sensor, 26 ultrasonic level meter, 27 pressure sensor, 28 outlet water tank, 29 first aeration electric valve, 30 first flushing electric valve, 31 second aeration electric valve, 32 second flushing electric valve, 33 first rotor flowmeter, 34 second rotor flowmeter, 35 water distribution main pipe, 36 water distribution branch pipe, 37 horizontal partition, 38 conical lower protrusion, 39 inclined baffle, 40 horizontal baffle, 41 rectangular cavity, 42 drain hole, 43 drain area. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] like Figure 1The figure shows a schematic structural diagram of a self-circulating sewage treatment device for a sludge expansion bed coupled with an MBR according to the present invention. The device comprises a reactor body 1, a raw water tank 5, an outlet water tank 28, a water distribution device 8, a finishing device 9, an aeration head 10, an MBR membrane assembly 11, an inlet water pump 7, a fan 21, a membrane outlet water suction pump 16, an overflow weir 1, a return line 14, and a PLC control box 19. The interior of the reactor body 1 is a hollow cavity, and the water distribution device 8 is disposed at the bottom of the reactor body 1. The raw water tank 5 stores the wastewater to be treated. The raw water tank 5 is connected to the water distribution device 8 via an inlet line 6 equipped with an inlet water pump 7. Above the water distribution device 8 is the sludge expansion bed area 2. The inlet water pump 7 pumps the wastewater to be treated into the water distribution device 8, which then evenly distributes the inlet water to the bottom of the sludge expansion bed area 2. A rectifier 9 is located in the center of the cavity within the reactor body 1. An aeration head 10 is positioned above the rectifier 9. Above the aeration head 10 is the aeration zone 3. The rectifier 9 ensures that sewage flows upward from the sludge expansion bed zone 2 into the aeration zone, while preventing sewage in the aeration zone 3 from flowing downward into the sludge expansion bed zone 2. A fan 21 is connected to the aeration head 10 via a pipeline equipped with a first aeration electric valve 29 and a first rotor flowmeter 33, allowing air to flow through the aeration head 10 to aerate the sewage in the reactor body 1.

[0047] Above the aeration zone 3 is the membrane separation zone 4, which houses an MBR membrane assembly 11. The outlet of the MBR membrane assembly 11 is connected to an outlet tank 28 via a membrane outlet electric valve 15 and a membrane outlet suction pump 16. The MBR membrane assembly 11 traps suspended flocculent sludge in the internal cavity of the reactor body 1. The clear water produced by filtration by the MBR membrane assembly 11 enters the outlet tank 28 under the suction of the membrane outlet suction pump 16.

[0048] An overflow weir 13 is disposed at the upper end of the cavity within the reactor body 1. A return line 14 is located outside the reactor body 1. The upper end of the return line 14 communicates with the overflow weir 13, and the lower end of the return line 14 communicates with the water distribution device 8. Under the aeration action of the aeration head 10, the aerated sewage rises within the reactor body 1, causing the liquid level at the upper end of the reactor body 1 to rise. Due to the liquid level difference, the sewage at the upper end of the reactor body 1 flows into the overflow weir 13. At the same time, the density and pressure of the sewage in the aeration zone 3 decrease after aeration. Due to the pressure difference, the sewage in the return line 14 enters the sludge expansion bed zone 2 through the water distribution device 8. The sludge expansion bed zone 2 then enters the aeration zone 3 upstream. This achieves a reciprocating flow of sewage in the reactor body 1 and the return line 14, thereby achieving a reciprocating purification treatment of the sewage.

[0049] In order to backwash the MBR membrane assembly 11, prevent membrane flux reduction and membrane clogging, and extend its service life, the outlet water tank 28 is connected to the water outlet of the MBR membrane assembly 11 via a pipeline equipped with a backwash electric valve 17 and a backwash suction pump 18. When backwashing the MBR membrane assembly 11 with water, the membrane outlet water electric valve 15 and the membrane outlet water suction pump 16 are closed, and the backwash electric valve 17 and the backwash suction pump 18 are opened, and the clear water in the outlet water tank 28 is reversed and enters the water outlet of the MBR membrane assembly 11 to achieve water cleaning of the MBR membrane assembly 11.

[0050] An aeration and flushing device 12 is located directly below the MBR membrane assembly 11. This device uses aeration to clean the MBR membrane assembly 11. To supply air to the aeration and flushing device 12, the outlet of the fan 21 is connected to the aeration and flushing device 12 via a pipeline equipped with a first flushing electric valve 30. When the fan 21 is used to aerate and oxygenate the sewage through the aeration head 10, the first aeration electric valve 29 is opened and the first flushing electric valve 30 is closed. When the MBR membrane assembly 11 is cleaned, the first flushing electric valve 30 is opened and the first aeration electric valve 29 is closed. When cleaning the MBR membrane assembly 11, the backwash suction pump 18, fan 21, and first flushing electric valve 30 are simultaneously activated to achieve combined gas-liquid in-situ cleaning of the MBR membrane assembly 11, thereby extending the service life of the membrane assembly and enhancing the treatment effect.

[0051] When using the sewage treatment device of the present invention to treat low- to medium-concentration urban wastewater, aerobic reactions occur in the aeration zone 3 and membrane separation zone 4, so it is possible to use fan 21 to draw in air for aeration and clean the MBR membrane assembly 11. However, when using it to treat high-concentration industrial wastewater, since the entire process is anaerobic, fan 21 cannot be used to draw in air for aeration and membrane cleaning. Aeration and membrane cleaning require a gas that does not affect the anaerobic environment. Therefore, a gas storage tank 22 is provided to collect and utilize biogas (primarily methane).

[0052] The top of the reactor body 1 is a gas-liquid separation zone 20, which is connected to a gas storage tank 22 via a pipeline equipped with a negative pressure air pump 24. When the sewage treatment device of the present invention is used to treat high-concentration industrial wastewater, the generated biogas is pumped into the gas storage tank 22 by the negative pressure air pump 24. The air inlet of the biogas compressor 23 is connected to the gas storage tank 22. The air outlet of the biogas compressor 23 is connected to the aeration head 10 through a pipeline equipped with a second aeration electric valve 31 and a second rotor flowmeter 34. The air outlet of the biogas compressor 23 is connected to the aeration head 10 through a pipeline equipped with a second flushing electric valve 32, and then to the aeration flushing device 12 through a pipeline equipped with a second flushing electric valve 32, respectively, to achieve aeration and gas cleaning of the MBR membrane assembly 11.

[0053] The reactor body 1 is equipped with a DO and pH sensor 25, an ultrasonic level gauge 26, and a pressure sensor 27. The PLC control box 19 is connected to the DO and pH sensor 25, the ultrasonic level gauge 26, and the pressure sensor 27 via signal lines to detect the oxygen content, pH, and liquid level of the wastewater in the reactor body 1. The PLC control box 19 is also connected to a first rotor flowmeter 33 and a second rotor flowmeter 34 via signal lines to detect the aeration volume. The PLC control box 19 is connected to the inlet pump 7, the membrane outlet suction pump 16, the backwash suction pump 18, the fan 21, the biogas compressor 23, the negative pressure air pump 24, the membrane outlet electric valve 15, the backwash electric valve 17, the first aeration electric valve 29, the first flushing electric valve 30, the second aeration electric valve 31, and the second flushing electric valve 32 via control lines to control the start and stop of the pumps, fans, and compressors, as well as the opening and closing of the electric valves.

[0054] The water distribution device 8 shown in the figure consists of a main water distribution pipe 35 and branch water distribution pipes 36 evenly arranged on both sides of the main water distribution pipe 8. The branch water distribution pipes 36 communicate with the main water distribution pipe 35 and are arranged at an angle of 15° to 30° with the horizontal plane. The branch water distribution pipes 36 are evenly distributed with multiple downward-facing water distribution holes. The sewage flowing out of the water distribution holes increases the turbulence of the inlet water, facilitating the dispersal of sludge at the bottom of the reactor and preventing sludge from accumulating and forming a dead zone at the bottom of the reactor.

[0055] As the aeration head 10 aerates the sewage in the aeration zone 3, the pressure of the aerated lower sewage decreases, and the sewage accelerates to rise in liquid level under the action of the pressure difference. Part of the sewage enters the membrane separation zone, while most of the sewage flows into the overflow weir 13 under the action of the liquid level difference, and then enters the return pipe 14. The return sewage and the incoming water flow to the bottom of the reactor body 1, and only the aeration power source provided by the aeration head 10 in the aeration zone 3 is used to complete the self-circulating flow from the aeration zone 3 through the return pipe 14 to the sludge expansion bed zone 2, and then to the top aeration zone 3 and the membrane separation zone 4.

[0056] The top of overflow weir 13 is serrated, with the highest point of the return line 14's inlet lower than the weir's top edge and the lowest point higher than the weir's bottom. The serrated top of overflow weir 13 ensures uniform flow of sewage from the system to the return line's inlet, ensuring uniform return water quality and volume.

[0057] The MBR membrane assembly 11 shown can be a hollow fiber membrane or a ceramic membrane, and its pore size can be an ultrafiltration membrane with a 0.01-0.1 μm pore size, which can completely intercept suspended solids so that the effluent water quality is not affected by the rising flow rate, and the effluent can directly enter the deep treatment stage.

[0058] like Figure 2As shown, a structural schematic diagram of the rectifying device in the present invention is given. The rectifying device 9 shown is composed of a horizontal plate 37 and a conical lower convex portion 38 arranged in the center of the horizontal plate 37. The two sides of the horizontal plate 37 are rectangular cavities 41 connecting the sludge expansion bed area 2 and the aeration area 3. Drainage holes 42 are evenly opened on the horizontal plate. The conical lower convex portion is composed of spaced inclined baffles 39 and spaced horizontal baffles 40. Drainage areas 43 are formed between adjacent inclined baffles 39 and adjacent horizontal baffles; the angle between the inclined baffle 39 and the horizontal direction is 45°~60°; the horizontal baffle 37, the inclined baffle 39 and the horizontal baffle 40 realize the blocking of the downward flowing water, and the upward flowing water enters the aeration area 3 through the rectangular cavity 41, the drainage holes 42 and the drainage area 43. In this way, the rectifying device 9 causes part of the water flow directly returning from the aeration area to the sludge expansion bed area to dissipate energy and slow down. At the same time, only a small amount of water flows downward through the rectifying device, thereby causing the main body of the water flow to flow upward and undergo a more complete treatment process.

[0059] like Figure 3 As shown, a flow chart of the environmental sewage treatment device of the present invention for treating medium and low concentration urban wastewater is given, which is achieved by the following steps:

[0060] a). Inoculation of sludge: Inoculate granular sludge with good endogenous denitrification performance in the sludge expansion bed area at the bottom of the reactor body, and ensure that the sludge concentration is high after inoculation, and at the same time ensure that the inoculated granular sludge contains a certain proportion of glycogen-accumulating bacteria GAOs;

[0061] b) Start the system; the PLC control box controls the opening of the water inlet pump, the first aeration electric valve and the fan to allow the treated sewage in the raw water tank to enter the reactor body, and the sewage in the reactor body is aerated under the action of the fan;

[0062] c) Influent and anaerobic reaction: The untreated sewage in the raw water tank and the return sewage from the return pipe enter the sludge expansion bed area through the water distribution device at the bottom of the reactor body. Anaerobic reaction occurs under the biochemical action of anaerobic microorganisms in the granular sludge. Most nitrifying bacteria use the COD in the influent as an external carbon source to convert oxidized nitrogen into nitrogen gas for removal. At the same time, some denitrifying bacteria, glycogen-accumulating bacteria GAOs and phosphate-accumulating bacteria PAOs use polyhydroxyalkanoates (PHAs) and glycogen (Gly) stored in their cells as electron donors to carry out endogenous denitrification and denitrification.

[0063] d) Aeration, aerobic reaction and backflow: When sewage flows into the aeration zone, ammonia-oxidizing bacteria AOB and nitrite-oxidizing bacteria NOB oxidize ammonia nitrogen into nitrite nitrogen through the dissolved oxygen provided by the aeration head, maintaining the dissolved oxygen concentration at 0.5-2.0 mg / L. When the dissolved oxygen concentration is lower than 0.5 mg / L, the aeration intensity is increased, and when it is higher than 2.0 mg / L, the aeration intensity is reduced;

[0064] At the same time, during the aerobic reaction, the aeration head aerates and oxygenates the sewage in the lower layer of the aeration zone. The pressure of the aerated sewage in the lower layer decreases, and the water level rises rapidly, flowing into the overflow weir and then into the return pipe. The inlet water of the raw water tank and the return sewage in the return pipe flow to the bottom of the reactor body and pass through the sludge expansion bed area and aeration area for purification again. Under the action of the hydraulic shear force provided by aeration, the flocculent sludge with poor settling performance rises, while the sludge with good settling performance falls, forming granular sludge that falls to the sludge expansion bed area below.

[0065] e) Sewage rectification: Under the action of the horizontal baffles, inclined baffles and horizontal baffles in the rectification device, the water flow returning from the aeration zone to the sludge expansion bed zone is decelerated and energy is reduced, so that only a small amount of sewage flows downward through the rectification device, thereby causing the main flow to flow upward;

[0066] f) Effluent and return flow: The sewage flows to the top of the reactor, and most of the water flows into the return pipe through the overflow weir and returns to the bottom of the reactor body. Then, the pollutants in the sewage are further degraded through the above steps c) and d) and the pollutant content is recycled several times until the pollutant content meets the standard. A small amount of sewage flows into the membrane separation area, and the membrane effluent suction pump produces clear water that enters the effluent tank and subsequently enters the deep treatment unit. The floating flocculent sludge is intercepted by the MBR membrane assembly in the reactor body, so that the sludge concentration in the reactor body is maintained at a high level.

[0067] g) Backwashing: Regularly turn on the fan and the first flushing electric valve to deliver air to the aeration flushing device to the MBR membrane assembly. At the same time, turn on the backwash suction pump and backwash electric valve to extract a certain amount of water from the outlet water tank and reversely deliver it to the MBR membrane assembly for gas-liquid combined backwashing to enhance the backwashing effect and extend the service life of the MBR membrane assembly.

[0068] like Figure 4 As shown in FIG, a flow chart of the environmental pollution treatment device of the present invention for treating high-concentration industrial wastewater is given, which is achieved by the following steps:

[0069] 1) Inoculation of sludge: Inoculate a certain amount of anaerobic granular sludge in the sludge expansion bed area at the bottom of the reactor body, and ensure that the sludge concentration is high after inoculation, and at the same time ensure that the inoculated granular sludge contains a certain proportion of acid-producing bacteria and methanogens;

[0070] 2) Start the system; the PLC control box controls the start of the water inlet pump, negative pressure air pump, second aeration electric valve and biogas compressor to allow the treated sewage in the raw water tank to enter the reactor body, and the biogas compressor aerates the sewage in the reactor body;

[0071] 3) Water inlet and anaerobic reaction: The untreated sewage in the raw water tank and the return sewage from the return pipe enter the sludge expansion bed area through the water distribution device at the bottom of the reactor body. Anaerobic digestion occurs under the biochemical action of anaerobic microorganisms in the anaerobic granular sludge. The organic matter in the sewage is first hydrolyzed and acidified into short-chain fatty acids and alcohols. Acidogenic bacteria further convert the short-chain fatty acids and alcohols into ethanol. Finally, the ethanol is used by methanogens to produce methane.

[0072] 4) Methane and sewage are charged into the circulation system. The sewage flows to the aeration zone, where the methane biogas in the gas storage tank is transported to the aeration head through the biogas compressor to aerate the sewage. Under the action of the gas generated in the aeration head and the sludge expansion bed area, the sewage pressure in the aeration and sludge expansion bed areas decreases, causing the sewage level to rise faster until it flows into the overflow weir and then into the return line. The return sewage and the influent water flow to the bottom of the reactor body, forming a circulation flow to treat the sewage.

[0073] At the same time, under the action of methane gas released by the aeration head, aeration provides hydraulic shear force, causing flocculent sludge with poor settling performance to rise and sludge with good settling performance to fall, forming granular sludge that falls to the sludge expansion bed area below. The timing and frequency of biogas compressor filling through the aeration head are determined by the DO and pH sensor and the 6 ultrasonic level meter online detection values. When the DO and pH sensors detect that the DO in the sewage is greater than 0.5mg / L or the liquid level remains below the overflow weir for a long time, the compressor is used to send biogas into the aeration head for aeration.

[0074] 5) Sewage rectification: Under the action of the horizontal baffles, inclined baffles and horizontal baffles in the rectification device, the water flow returning from the aeration area to the sludge expansion bed area is decelerated and decelerated, so that only a small amount of sewage flows downward through the rectification device, thereby making the main flow flow upward;

[0075] 6) Effluent and return flow: The sewage flows to the top of the reactor, and most of the water flows into the return pipe through the overflow weir and returns to the bottom of the reactor body. Then, the pollutants in the sewage are further degraded through the above steps 3) and 4). After multiple cycles of treatment, the pollutant content reaches the standard. A small amount of sewage flows into the membrane separation area and further undergoes anaerobic reaction with the sludge intercepted by the MBR membrane module to produce methane. The clear water obtained by the membrane outlet suction pump enters the water outlet tank, and the water in the water outlet tank subsequently enters the deep treatment unit. The gas generated by the reactor body is collected by the negative pressure air pump through the top gas-liquid separation area and sent to the gas storage tank;

[0076] 7) Backwashing: The backwashing suction pump 18 extracts a certain amount of water and sends it back to the MBR membrane assembly for backwashing. In addition, the biogas compressor is used to regularly send biogas from the gas storage tank to the aeration flushing device to backwash the membrane assembly to extend the service life of the MBR membrane assembly.

Claims

1. A method for treating medium- and low-concentration urban wastewater using a self-circulating sewage treatment device of a sludge expansion bed coupled with an MBR, the self-circulating sewage treatment device of the sludge expansion bed coupled with an MBR comprising a reactor body (1), a raw water tank (5), an outlet water tank (28), a water distribution device (8), a rectifying device (9), an aeration head (10), a fan (21), an overflow weir (13), a return pipe (14), and a PLC control box (19), wherein the interior of the reactor body is a cavity, the water distribution device is arranged at the bottom of the cavity inside the reactor body, the raw water tank is connected to the water distribution device via an inlet pipe (6) and an inlet pump (7), the rectifying device is located in the middle of the cavity inside the reactor body, a sludge expansion bed area (2) is formed between the water distribution device and the rectifying device, and granular sludge for treating sewage is inoculated in the sludge expansion bed area; The overflow weir is located at the upper part of the internal cavity of the reactor body, the upper end of the return pipe is connected to the overflow weir, and the lower end is connected to the water distribution device; the reactor body is provided with DO and pH sensors (25), an ultrasonic level meter (26) and a pressure sensor (27), and a PLC control box controls the operation of the sewage treatment device; the aeration head is located in the middle of the internal cavity of the reactor body and above the rectifier device, the fan is connected to the aeration head through a pipeline provided with a first aeration electric valve (29) and a first rotor flowmeter (33), and the upper part of the aeration head forms an aeration zone (3); the upper part of the aeration zone forms a membrane separation zone (4), and the membrane separation zone is provided with an MBR membrane assembly (11), and the water outlet of the MBR membrane assembly is connected to the water outlet tank through a pipeline provided with a membrane water outlet electric valve (15) and a membrane water outlet suction pump (16); Under the aeration effect of the fan on the aeration area through the aeration head, the density of the water in the middle of the cavity inside the reactor body is reduced and the pressure is lowered, so that the water in the sludge expansion bed area flows into the aeration area. The water in the aeration area flows upward with the aeration into the membrane separation area and flows into the overflow weir. The water in the overflow weir flows into the water distribution device through the return pipe and then into the sludge expansion bed area, realizing the circulation and purification of sewage under the action of aeration; the sewage after purification treatment is filtered by the MBR membrane module under the action of the membrane outlet suction pump and flows into the outlet water tank, and the floating flocculent sludge suspended matter is trapped in the reactor body; The invention comprises a gas storage tank (22), a backwash suction pump (18), a negative pressure air pump (24) and a biogas compressor (23), wherein the gas storage tank is used to store biogas, an aeration flushing device (12) is provided below the MBR membrane assembly (11), the top of the reactor body (1) is a gas-liquid separation zone (20), the outlet water tank (28) is connected to the water outlet of the MBR membrane assembly (11) through a pipeline provided with a backwash suction pump and a backwash electric valve (17), and the gas-liquid separation zone is connected to the water outlet of the MBR membrane assembly (11) through a pipeline provided with a backwash suction pump and a backwash electric valve (17). The pipeline of the air pump is connected to the air storage tank, and the air outlet of the fan (21) is connected to the aeration and flushing device via a pipeline provided with a first flushing electric valve (30); the air inlet of the biogas compressor is connected to the air storage tank, the air outlet of the biogas compressor is connected to the aeration head (10) via a pipeline provided with a second aeration electric valve (31) and a second rotor flowmeter (34), and the air outlet of the biogas compressor is connected to the aeration and flushing device via a pipeline provided with a second flushing electric valve (32); The PLC control box (19) is connected to the DO and pH sensors (25), the ultrasonic level meter (26), the pressure sensor (27), the first rotor flowmeter (33) and the second rotor flowmeter (34) via signal lines, and is connected to the inlet water pump (7), the membrane outlet water suction pump (16), the backwash suction pump (18), the fan (21), the biogas compressor (23), the negative pressure air pump (24), the membrane outlet water electric valve (15), the backwash electric valve (17), the first aeration electric valve (29), the first flushing electric valve (30), the second aeration electric valve (31) and the second flushing electric valve (32) via control lines; It is characterized in that The method for treating low- and medium-concentration urban wastewater by a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR is achieved through the following steps: a). Inoculation of sludge: Inoculate granular sludge with good endogenous denitrification performance in the sludge expansion bed area at the bottom of the reactor body, and ensure that the sludge concentration is high after inoculation, and at the same time ensure that the inoculated granular sludge contains a certain proportion of glycogen-accumulating bacteria GAOs; b) Start the system; the PLC control box controls the opening of the water inlet pump, the first aeration electric valve and the fan to allow the treated sewage in the raw water tank to enter the reactor body, and the sewage in the reactor body is aerated under the action of the fan; c) Influent and anaerobic reaction: The untreated sewage in the raw water tank and the return sewage from the return pipe enter the sludge expansion bed area through the water distribution device at the bottom of the reactor body. Anaerobic reaction occurs under the biochemical action of anaerobic microorganisms in the granular sludge. Most nitrifying bacteria use the COD in the influent as an external carbon source to convert oxidized nitrogen into nitrogen gas for removal. At the same time, some denitrifying bacteria, glycogen-accumulating bacteria GAOs and phosphate-accumulating bacteria PAOs use polyhydroxyalkanoates (PHAs) and glycogen (Gly) stored in their cells as electron donors to carry out endogenous denitrification and denitrification. d) Aeration, aerobic reaction and backflow: When sewage flows into the aeration zone, ammonia-oxidizing bacteria AOB and nitrite-oxidizing bacteria NOB oxidize ammonia nitrogen into nitrite nitrogen through the dissolved oxygen provided by the aeration head, maintaining the dissolved oxygen concentration at 0.5-2.0 mg / L. When the dissolved oxygen concentration is lower than 0.5 mg / L, the aeration intensity is increased, and when it is higher than 2.0 mg / L, the aeration intensity is reduced; At the same time, during the aerobic reaction, the aeration head aerates and oxygenates the sewage in the lower layer of the aeration zone. The pressure of the aerated sewage in the lower layer decreases, and the water level rises rapidly, flowing into the overflow weir and then into the return pipe. The inlet water of the raw water tank and the return sewage in the return pipe flow to the bottom of the reactor body and pass through the sludge expansion bed area and aeration area for purification again. Under the action of the hydraulic shear force provided by aeration, the flocculent sludge with poor settling performance rises, while the sludge with good settling performance falls, forming granular sludge that falls to the sludge expansion bed area below. e). Sewage rectification; Under the action of the horizontal baffles, inclined baffles and horizontal baffles in the rectifier, part of the water flow returning from the aeration area to the sludge expansion bed area is decelerated and energy is reduced, so that only a small part of the sewage flows downward through the rectifier, thereby causing the main body of the water flow to flow upward; f) Effluent and reflux; The sewage flows to the top of the reactor, and most of the water flows through the overflow weir into the reflux pipe and flows back to the bottom of the reactor body, and then undergoes the above steps c) and d) to further degrade the pollutants in the sewage, and after multiple cycles of treatment, the pollutant content reaches the standard; A small amount of sewage flows into the membrane separation area, and under the action of the membrane outlet water suction pump, clear water is obtained and enters the outlet water tank, and then enters the deep treatment unit. The floating flocculent sludge is intercepted by the MBR membrane assembly in the reactor body, so that a high sludge concentration is maintained in the reactor body; g) Backwashing: Regularly turn on the fan and the first flushing electric valve to deliver air to the aeration flushing device to the MBR membrane assembly. At the same time, turn on the backwash suction pump and backwash electric valve to extract a certain amount of water from the outlet water tank and reversely deliver it to the MBR membrane assembly for gas-liquid combined backwashing to enhance the backwashing effect and extend the service life of the MBR membrane assembly.

2. The method for treating medium- and low-concentration urban wastewater using a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR according to claim 1, characterized in that: The rectifying device (9) is composed of a horizontal plate (37) and a conical lower convex portion (38) arranged in the center of the horizontal plate. The two sides of the horizontal plate are rectangular cavities (41) connecting the sludge expansion bed area (2) and the aeration area (3). The horizontal plate is evenly provided with drainage holes (42). The conical lower convex portion is composed of inclined baffles (39) and horizontal baffles (40) arranged at intervals. A drainage area (43) is formed between adjacent inclined baffles and adjacent horizontal baffles. The angle between the inclined baffles and the horizontal direction is 45° to 60°. The horizontal baffles, the inclined baffles and the horizontal baffles block the downward flowing water flow. The upward flowing water enters the aeration area (3) through the rectangular cavity, the drainage holes and the drainage area.

3. The method for treating medium- and low-concentration urban wastewater using a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR according to claim 1, characterized in that: The water distribution device (8) is composed of a water distribution main pipe (35) and water distribution branch pipes (36) evenly arranged on both sides of the water distribution main pipe. The water distribution branch pipes are connected to the water distribution main pipe. The angle between the water distribution branch pipes and the horizontal plane is 15° to 30°. A plurality of downward-facing water distribution holes are evenly opened on the water distribution branch pipes.

4. The method for treating medium- and low-concentration urban wastewater using a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR according to claim 1, characterized in that: The MBR membrane assembly (11) is a hollow fiber membrane or a hollow ceramic membrane, and the pore size of the MBR membrane assembly is an ultrafiltration membrane with a 0.01 μm to 0.1 μm diameter.

5. The method for treating medium- and low-concentration urban wastewater using a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR according to claim 1, characterized in that: The top of the overflow weir (13) is a sawtooth upper edge, and the highest point of the water inlet of the return pipe (14) is lower than the upper edge of the overflow weir, and the lowest point is higher than the bottom of the overflow weir.

6. A method for treating high-concentration industrial wastewater using a self-circulating sewage treatment device of a sludge expansion bed coupled with an MBR, the self-circulating sewage treatment device of the sludge expansion bed coupled with an MBR comprising a reactor body (1), a raw water tank (5), an outlet water tank (28), a water distribution device (8), a rectifying device (9), an aeration head (10), a fan (21), an overflow weir (13), a return pipe (14) and a PLC control box (19), the interior of the reactor body being a cavity, the water distribution device being arranged at the bottom of the cavity inside the reactor body, the raw water tank being connected to the water distribution device via an inlet pipe (6) and an inlet pump (7); the rectifying device being located in the middle of the cavity inside the reactor body, a sludge expansion bed area (2) being formed between the water distribution device and the rectifying device, the sludge expansion bed area being inoculated with granular sludge for treating sewage; The overflow weir is located at the upper part of the internal cavity of the reactor body, the upper end of the return pipe is connected to the overflow weir, and the lower end is connected to the water distribution device; the reactor body is provided with DO and pH sensors (25), an ultrasonic level meter (26) and a pressure sensor (27), and a PLC control box controls the operation of the sewage treatment device; the aeration head is located in the middle of the internal cavity of the reactor body and above the rectifier device, the fan is connected to the aeration head through a pipeline provided with a first aeration electric valve (29) and a first rotor flowmeter (33), and the upper part of the aeration head forms an aeration zone (3); the upper part of the aeration zone forms a membrane separation zone (4), and the membrane separation zone is provided with an MBR membrane assembly (11), and the water outlet of the MBR membrane assembly is connected to the water outlet tank through a pipeline provided with a membrane water outlet electric valve (15) and a membrane water outlet suction pump (16); Under the aeration effect of the fan on the aeration area through the aeration head, the density of the water in the middle of the cavity inside the reactor body is reduced and the pressure is lowered, so that the water in the sludge expansion bed area flows into the aeration area. The water in the aeration area flows upward with the aeration into the membrane separation area and flows into the overflow weir. The water in the overflow weir flows into the water distribution device through the return pipe and then into the sludge expansion bed area, realizing the circulation and purification of sewage under the action of aeration; the sewage after purification treatment is filtered by the MBR membrane module under the action of the membrane outlet suction pump and flows into the outlet water tank, and the floating flocculent sludge suspended matter is trapped in the reactor body; The invention comprises a gas storage tank (22), a backwash suction pump (18), a negative pressure air pump (24) and a biogas compressor (23), wherein the gas storage tank is used to store biogas, an aeration flushing device (12) is provided below the MBR membrane assembly (11), the top of the reactor body (1) is a gas-liquid separation zone (20), the outlet water tank (28) is connected to the water outlet of the MBR membrane assembly (11) through a pipeline provided with a backwash suction pump and a backwash electric valve (17), and the gas-liquid separation zone is connected to the water outlet of the MBR membrane assembly (11) through a pipeline provided with a backwash suction pump and a backwash electric valve (17). The pipeline of the air pump is connected to the air storage tank, and the air outlet of the fan (21) is connected to the aeration and flushing device via a pipeline provided with a first flushing electric valve (30); the air inlet of the biogas compressor is connected to the air storage tank, the air outlet of the biogas compressor is connected to the aeration head (10) via a pipeline provided with a second aeration electric valve (31) and a second rotor flowmeter (34), and the air outlet of the biogas compressor is connected to the aeration and flushing device via a pipeline provided with a second flushing electric valve (32); The PLC control box (19) is connected to the DO and pH sensors (25), the ultrasonic level meter (26), the pressure sensor (27), the first rotor flowmeter (33) and the second rotor flowmeter (34) via signal lines, and is connected to the inlet water pump (7), the membrane outlet water suction pump (16), the backwash suction pump (18), the fan (21), the biogas compressor (23), the negative pressure air pump (24), the membrane outlet water electric valve (15), the backwash electric valve (17), the first aeration electric valve (29), the first flushing electric valve (30), the second aeration electric valve (31) and the second flushing electric valve (32) via control lines; It is characterized in that The method for treating high-concentration industrial wastewater by a self-circulating sewage treatment device of a sludge expanded bed coupled with an MBR is achieved by the following steps: 1) Inoculation of sludge: Inoculate a certain amount of anaerobic granular sludge in the sludge expansion bed area at the bottom of the reactor body, and ensure that the sludge concentration is high after inoculation, and at the same time ensure that the inoculated granular sludge contains a certain proportion of acid-producing bacteria and methanogens; 2) Start the system; the PLC control box controls the start of the water inlet pump, negative pressure air pump, second aeration electric valve and biogas compressor to allow the treated sewage in the raw water tank to enter the reactor body, and the biogas compressor aerates the sewage in the reactor body; 3) Water inlet and anaerobic reaction: The untreated sewage in the raw water tank and the return sewage from the return pipe enter the sludge expansion bed area through the water distribution device at the bottom of the reactor body. Anaerobic digestion occurs under the biochemical action of anaerobic microorganisms in the anaerobic granular sludge. The organic matter in the sewage is first hydrolyzed and acidified into short-chain fatty acids and alcohols. Acidogenic bacteria further convert the short-chain fatty acids and alcohols into ethanol. Finally, the ethanol is used by methanogens to produce methane. 4) Methane and sewage are charged into the circulation system. The sewage flows to the aeration zone, where the methane biogas in the gas storage tank is transported to the aeration head through the biogas compressor to aerate the sewage. Under the action of the gas generated in the aeration head and the sludge expansion bed area, the sewage pressure in the aeration and sludge expansion bed areas decreases, causing the sewage level to rise faster until it flows into the overflow weir and then into the return line. The return sewage and the influent water flow to the bottom of the reactor body, forming a circulation flow to treat the sewage. At the same time, under the action of methane gas released by the aeration head, aeration provides hydraulic shear force, causing flocculent sludge with poor settling performance to rise and sludge with good settling performance to fall, forming granular sludge that falls to the sludge expansion bed area below. The timing and frequency of biogas compressor filling through the aeration head are determined by the DO and pH sensor and the 6 ultrasonic level meter online detection values. When the DO and pH sensors detect that the DO in the sewage is greater than 0.5mg / L or the liquid level remains below the overflow weir for a long time, the compressor is used to send biogas into the aeration head for aeration. 5). Sewage rectification; Under the action of the horizontal baffles, inclined baffles and horizontal baffles in the rectifier, part of the water flow returning from the aeration area to the sludge expansion bed area is decelerated and energy is reduced, so that only a small part of the sewage flows downward through the rectifier, thereby causing the main body of the water flow to flow upward; 6) Effluent and reflux: The sewage flows to the top of the reactor, and most of the water flows into the reflux pipe through the overflow weir and flows back to the bottom of the reactor body. Then, the above steps 3) and 4) are performed to further degrade the pollutants in the sewage. After multiple cycles of treatment, the pollutant content reaches the standard. A small amount of sewage flows into the membrane separation area and further undergoes anaerobic reaction with the sludge intercepted by the MBR membrane module to produce methane. The clear water produced by the membrane outlet suction pump enters the outlet water tank, and the water produced in the outlet water tank subsequently enters the deep treatment unit; the gas produced by the reactor body is collected by the negative pressure air pump through the top gas-liquid separation area and sent to the gas storage tank; 7) Backwashing: The backwash suction pump is used to extract a certain amount of water and send it back to the MBR membrane assembly for backwashing. In addition, the biogas in the gas storage tank is regularly sent to the aeration and flushing device through the biogas compressor to backwash the membrane assembly to extend the service life of the MBR membrane assembly.

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