An anaerobic membrane bioreactor for mitigating membrane fouling

Abstract

The application discloses an anaerobic membrane bioreactor, which comprises a reactor main body, a gas collection sealing cover and a gas recovery-reflux assembly, the reactor main body carries out anaerobic biological reaction and membrane separation; the gas collection sealing cover collects biogas generated in the anaerobic reaction, and discharges the biogas to the gas recovery-reflux assembly outside the reactor main body; and the gas recovery-reflux assembly is used for storing the biogas collected by the gas collection sealing cover and refluxing part of the biogas to the inside of the reactor main body to flush the membrane assembly for carrying out membrane separation in the reactor main body. The anaerobic reaction and the membrane separation of the reactor of the application are separated from each other, the upward flow velocity of sewage is high, the growth condition of anaerobic microorganisms is healthy, and the adverse effect of aeration on the growth of the microorganisms is reduced; the sludge concentration in the membrane separation chamber is low, the adsorption of the sludge on the surface of the membrane assembly is reduced, and the membrane pollution is slowed down; and the membrane assembly is flushed by the self-generated biogas, so that the energy consumption is reduced, and the membrane pollution is further slowed down.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to the field of anaerobic membrane bioreactor technology that can mitigate membrane fouling. Background Technology

[0002] Water is the source of life. With industrial development, factories are generating increasing amounts of difficult-to-treat wastewater. Indiscriminate discharge pollutes natural water bodies, damages the ecological environment, and threatens human health. Various types of industrial wastewater urgently need to be rendered harmless and recycled. Currently, anaerobic biological treatment processes are widely used as the primary treatment unit for various industrial wastewaters, achieving certain treatment results.

[0003] Anaerobic processes offer high organic loading and the ability to treat recalcitrant pollutants, enabling them to treat various types of high-concentration, recalcitrant industrial wastewater and meet industrial wastewater treatment needs. Furthermore, anaerobic processes have low energy consumption and can recover biogas energy. Under the "dual carbon" goal (referring to carbon sequestration and carbon emissions), anaerobic processes are inevitably the future development trend. Various types of anaerobic reactors are already in use, such as UASB and IC reactors. However, these reactors all suffer from biomass loss, resulting in poor operating performance, hindering the increase of organic loading, and reducing biogas production.

[0004] Anaerobic membrane bioreactors (AnMBRs) are anaerobic reactors that use membrane modules as filtration units. Membrane modules can reduce sludge loss, increase the sludge concentration of anaerobic organisms, and improve the reactor's organic loading, making them a promising type of anaerobic reactor. However, anaerobic sludge is highly viscous, making it more prone to membrane fouling. Membrane fouling increases the operating costs of AnMBRs, hindering their application.

[0005] Therefore, it is necessary to design an anaerobic membrane bioreactor that can mitigate membrane fouling in order to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned technical problems by providing a novel anaerobic membrane bioreactor. Compared to existing AnMBRs, the anaerobic membrane bioreactor of this invention features an independent anaerobic reaction zone and a membrane separation zone, reducing the concentration of anaerobic sludge in contact with the membrane module and mitigating membrane fouling. Furthermore, the wastewater distribution system and aeration system of this bioreactor are separated, resulting in a difference between the upflow velocity of wastewater and sludge in the anaerobic reaction chamber and the aeration velocity in the membrane separation chamber. This allows for the setting of an appropriate wastewater upflow velocity to achieve optimal microbial growth and reduce the adverse effects of aeration on microbial growth. A sludge return port is located at the bottom of the baffle separating the anaerobic reaction chamber and the membrane separation chamber, returning the sludge settled in the membrane separation chamber to the anaerobic reaction chamber. Additionally, the sludge return plate at the bottom of the membrane separation chamber is inclined towards the anaerobic reaction chamber, collecting the sludge settled in the membrane separation chamber towards the anaerobic reaction chamber and then returning it to the anaerobic reaction chamber through the sludge return port. This uses a sludge return port instead of a sludge return pump, reducing energy consumption.

[0007] To achieve the objectives of this invention, one aspect of this invention provides an anaerobic membrane bioreactor for mitigating membrane fouling, comprising a reactor body, a gas collection sealing hood, and a gas recovery-recirculation assembly, wherein:

[0008] The main body of the reactor is used for anaerobic biological reaction and membrane separation of wastewater to produce effluent;

[0009] The gas collection sealing cover is used to collect the biogas produced by the anaerobic reaction inside the reactor body and discharge the biogas to the gas recovery-recirculation assembly outside the reactor body;

[0010] The gas recovery-recirculation assembly is located outside the reactor body and is fixedly connected to the top of the gas collection sealing hood. It is used to store the biogas collected by the gas collection sealing hood and to return a portion of the biogas to the inside of the reactor body to flush the membrane module inside the reactor body that performs membrane separation.

[0011] The gas collecting sealing cover is conical or inverted funnel-shaped, and the shape and size of its bottom match the shape and size of the top of the reactor body.

[0012] In particular, the gas collection sealing cover is provided with an exhaust port, a detection port, and a water outlet. The exhaust port is connected to the gas recovery-recirculation component; the detection port is used to fix and install the oxidation-reduction potential detection electrode; and the water outlet is used to fix and install the water outlet pipe for the water purified by membrane separation in the reactor body.

[0013] Specifically, the gas recovery-recirculation assembly includes an exhaust pipe, a biogas storage tank, a gas return pipe, and a biogas circulation pump. One end of the exhaust pipe is sealed to a gas collection sealing cover, and the other end is connected to the biogas storage tank mounted on the exhaust pipe. One end of the gas return pipe is connected to the bottom of the biogas storage tank, and the other end is connected to a gas distribution pipe located at the bottom of the reactor body, returning a portion of the biogas stored in the biogas storage tank to the interior of the reactor body. The biogas circulation pump is mounted on the gas return pipe and is used to pressurize the biogas returning to the reactor body, ensuring that the returned biogas has a certain pressure.

[0014] In particular, the reactor body is cylindrical and hollow inside, including baffles installed inside the reactor body, and anaerobic reaction chambers and membrane separation chambers located on both sides of the baffles, wherein: the baffles are arranged along the longitudinal section of the reactor body; the anaerobic reaction chamber is filled with activated sludge, and wastewater enters the anaerobic reaction chamber and mixes with the activated sludge to carry out anaerobic reaction; the water after anaerobic reaction flows into the membrane separation chamber, and is separated by the membrane module installed in the membrane separation chamber to produce effluent.

[0015] In particular, the baffle is arranged along a longitudinal section passing through the central axis of the reactor body, dividing the reactor body into two relatively independent spatial regions of the same size.

[0016] In particular, the bottom of the baffle is fixedly installed on the bottom of the reactor body, and several elongated sludge return ports are opened at the bottom of the baffle to return the sludge settled in the membrane separation chamber to the anaerobic reaction chamber.

[0017] In particular, a three-phase separator and an oxidation-reduction potential detection electrode are installed at the top of the anaerobic reaction chamber. The oxidation-reduction potential detection electrode extends from the detection port of the gas collection sealing cover into the anaerobic reaction chamber of the reactor body to measure the temperature and oxidation-reduction potential of the water in the anaerobic reaction chamber. The three-phase separator is fixedly installed at the liquid surface inside the reactor body.

[0018] In particular, the installation height of the three-phase separator is consistent with the liquid level in the anaerobic reaction chamber.

[0019] In particular, the membrane separation chamber is equipped with a membrane module, a sludge return plate, and an aeration assembly, wherein:

[0020] The membrane module is submerged below the liquid surface in the membrane separation chamber. The outlet of the membrane module is connected to the outlet pipe 8, and the effluent after membrane separation is discharged from the reactor through the outlet pipe.

[0021] The sludge return plate is located below the membrane module and is inclined. Its bottom is fixedly installed at the bottom of the reactor body and is fixed together with the side of the baffle facing the membrane separation chamber. Its upper end is higher than the bottom and is inclined towards the anaerobic reaction chamber.

[0022] The aeration unit is located below the membrane module and includes air distribution pipes, aeration pipes, and aeration heads. The gas generated by the aeration heads washes over the membrane module, cleans the membrane fibers, and reduces membrane fouling.

[0023] In particular, the gas distribution pipe is located below the sludge return plate, is T-shaped, and its tail end is connected to the biogas return pipe located outside the reactor body to form a whole, and its end is fixedly connected to multiple aeration pipes to form a whole; the end of the aeration pipe is fixedly installed with an aeration head.

[0024] In particular, the sludge return plate is a semi-circular flat plate with multiple through holes at positions corresponding to the upper and lower parts of the membrane module. The aeration pipe of the aeration module passes through the through holes from the lower part of the sludge return plate upwards, extends into the membrane separation chamber, and extends to the bottom of the membrane module.

[0025] Compared with existing traditional anaerobic reactors, the beneficial effects of this invention are:

[0026] (1) Membrane modules mainly play a role in the final interception in anaerobic membrane bioreactors, improving the quality of effluent and reducing sludge loss.

[0027] (2) The anaerobic membrane bioreactor of the present invention has a three-phase separator installed on the top of the anaerobic reaction chamber, so that the sludge concentration in the membrane separation chamber is lower than that in the anaerobic reaction chamber. The low sludge concentration in the membrane separation chamber effectively reduces the amount of sludge adsorbed on the surface of the membrane module and effectively slows down membrane fouling.

[0028] The redox potential detection electrode with temperature probe is used to measure the temperature and redox potential of the reaction chamber, monitor the microbial status, and effectively control the anaerobic reaction in the anaerobic reaction chamber.

[0029] (3) Setting up an aeration system to flush the membrane surface helps to reduce membrane fouling. The gas continuously flushes the membrane surface, and under the action of shear force, the sludge adsorbed on the membrane surface is desorbed, thus reducing membrane fouling.

[0030] (4) Sludge return can be achieved. The aeration device extends from the bottom and is installed below the membrane module. Anaerobic microorganisms can settle from other parts of the membrane separation chamber and, using the sludge return plate, return the naturally settled sludge to the sludge return port under its own gravity, and then return it to the anaerobic reaction chamber from the sludge return port. At the same time, the upward flow velocity of the wastewater in the reaction chamber carries the settled sludge from the sludge return port into the reaction zone of the reaction chamber, where it re-participates in the anaerobic reaction, thus avoiding clogging of the sludge return port.

[0031] (5) Reduced energy consumption. The aeration system uses biogas generated by the reactor itself, which reduces energy consumption. Furthermore, the sludge returned to the membrane chamber is returned through the sludge return port, eliminating the need for a dedicated sludge return pump. This sludge return process further reduces energy consumption.

[0032] (6) The anaerobic membrane bioreactor of the present invention is equipped with a separate membrane separation chamber, which decouples the wastewater distribution from the aeration pipes, aeration heads, and gas recovery-recirculation components used for washing the membrane modules. A suitable upward flow velocity is set to achieve optimal microbial growth. The impact of aeration on microbial growth is reduced.

[0033] The three-phase separator separates biogas from the aqueous phase. After being collected by a gas collection seal, the biogas is discharged from the reactor body and stored in a biogas storage tank. A biogas circulation pump returns a portion of the biogas to the membrane separation chamber through a gas return pipe. After aeration by aeration heads located below the membrane module, the gas continuously washes the surface of the membrane module, desorbing the sludge adsorbed on the membrane surface under shear force. Utilizing the biogas produced by the reactor itself to wash the membrane module improves energy utilization. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the anaerobic membrane bioreactor of the present invention;

[0035] Figure 2 This is a schematic diagram of the bottom water distribution pipe and aeration pipe of the anaerobic membrane bioreactor of the present invention;

[0036] Figure 3 This is a schematic diagram of the anaerobic reaction chamber of the anaerobic membrane bioreactor of the present invention;

[0037] Figure 4 This is a schematic diagram of the membrane separation chamber of the anaerobic membrane bioreactor of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Inlet pipe; 2. Gas valve; 3. Water distribution hole; 4. Baffle; 5. Three-phase separator; 6. Oxidation-reduction potential detection electrode; 7. Membrane module; 8. Outlet pipe; 81. Drain valve; 9. Sludge return plate; 91. Support; 10. Sludge return port; 11. Gas collection sealing cover; 12. Biogas storage tank; 13. Gas return pipe; 131. Second gas valve; 14. Aeration head; 15. Reactor body; 16. Anaerobic reaction chamber; 17. Membrane separation chamber; 18. Water distribution pipe; 19. Exhaust pipe; 20. Biogas circulation pump; 21. Gas distribution pipe; 22. Aeration pipe. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] The anaerobic membrane bioreactor for mitigating membrane fouling of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0042] In the description of this invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] like Figure 1 The anaerobic membrane bioreactor for mitigating membrane fouling of the present invention includes a reactor body 15, a gas collection and sealing hood 11, and a gas recovery-recirculation assembly, wherein:

[0044] The main body of the reactor is used for anaerobic biological reaction and membrane separation of wastewater to produce effluent;

[0045] The gas collection and sealing hood is used to collect the biogas produced by the anaerobic reaction inside the reactor body and discharge the biogas to the gas recovery-recirculation assembly outside the reactor body. The gas collection and sealing hood is detachably installed on the top of the reactor body to seal the reactor body, creating an anaerobic environment and ensuring that the reactor body is in an anaerobic state.

[0046] The gas recovery-recirculation assembly is located outside the reactor body and is fixedly connected to the top of the gas collection sealing hood, with the connection sealed. It is used to store the biogas collected by the gas collection sealing hood and to return a portion of the biogas to the inside of the reactor body to flush the membrane module inside the reactor body.

[0047] The gas collecting and sealing hood is conical or inverted funnel-shaped, and its bottom shape and size match the shape and size of the top of the reactor body. The gas collecting and sealing hood is equipped with an exhaust port, a detection port, and a water outlet (not shown in the attached diagram), wherein:

[0048] The exhaust port is located at the center of the top of the gas collection sealing cover, and is used to discharge the biogas collected by the gas collection sealing cover to the gas recovery-recirculation component; the exhaust port is sealed to the exhaust pipe 19 of the gas recovery-recirculation component (the connection is sealed);

[0049] The detection port and the water outlet are located on opposite sides of the central axial surface of the gas collection hood. The detection port is used to install the oxidation-reduction potential detection electrode 6. The water outlet is used to discharge the water separated by the membrane module. The water outlet and the water outlet pipe 8 of the membrane module pass through the gas collection sealing hood from the water outlet to discharge the water separated by the membrane module out of the reactor body. The water outlet and the water outlet are sealed together (i.e., the connection is sealed).

[0050] Gas recovery-recirculation assembly: includes an exhaust pipe 19, a biogas storage tank 12, a gas recirculation pipe 13, and a biogas circulation pump 20, wherein,

[0051] One end of the exhaust pipe is sealed to the exhaust port at the top center of the gas collection sealing cover, and the other end is connected to the biogas storage tank 12 to discharge the biogas generated by the anaerobic reaction in the reactor body and store it in the biogas storage tank.

[0052] The biogas storage tank is installed on the exhaust pipe and is used to store biogas discharged from the top of the gas collection and sealing cover;

[0053] One end of the gas return pipe 13 is connected to the biogas storage tank, and the other end is sealed to the T-shaped gas distribution pipe 21 located at the bottom of the reactor body. Part of the biogas stored in the biogas storage tank is returned to the membrane separation chamber 17, and the returned biogas flushes and cleans the membrane module 7. The remaining biogas is purified and reused.

[0054] A biogas circulation pump 20 is installed on the gas return pipe to pressurize the biogas returning to the reactor body, so that the biogas returning to the membrane separation chamber has a certain pressure to flush the membrane module.

[0055] A gas valve 2 is installed on the exhaust pipe between the exhaust port and the biogas storage tank, and a second gas valve 131 is installed between the gas return pipe and the biogas circulation pump 20.

[0056] The gas recovery-recirculation assembly is used to recirculate the biogas produced by the anaerobic reaction in the reactor. On the one hand, it ensures complete mixing in the reactor, and on the other hand, it is used to flush the membrane assembly to reduce sludge loss and lower operating costs.

[0057] The biogas generated by the reactor itself is recycled, which can ensure the complete mixing state of the reactor and can also be used to flush the membrane module to reduce sludge loss and reduce operating costs.

[0058] The reactor body is cylindrical and hollow inside. Baffles are installed inside the reactor body along the longitudinal section of the reactor body. The reactor body is divided into two relatively independent areas by the baffles 4: anaerobic reaction chamber 16 and membrane separation chamber 17. The anaerobic reaction chamber and membrane separation chamber are filled with anaerobic sludge. Membrane module 7 is also installed in the membrane separation chamber.

[0059] Baffles can also be set along the axial section of the reactor body, dividing the reactor body into two relatively independent areas of the same or different sizes: an anaerobic reaction chamber and a membrane separation chamber. If the two spatial areas are of different sizes, the larger side is the anaerobic reaction chamber, and the other side is the membrane separation chamber.

[0060] In a specific embodiment of the present invention, the baffle is arranged along the longitudinal section passing through the central axis of the reactor body. The baffle 4 divides the reactor body into two equal and relatively independent anaerobic reaction chambers and membrane separation chambers. The anaerobic reaction chamber and the membrane separation chamber are filled with anaerobic sludge. The membrane separation chamber is also equipped with a membrane module 7.

[0061] After entering the anaerobic reactor, the wastewater is mixed with activated sludge and undergoes anaerobic reactions, mainly including hydrolysis acidification, hydrogen production, acetic acid production, and methanogenesis. The water flows from bottom to top to the three-phase separator for solid-liquid-gas separation.

[0062] The baffle is a rectangular flat plate, set on the central axis of the cylindrical reactor body, that is, the baffle extends along the axis of the reactor body. The width of the baffle matches the diameter of the reactor body, and the height of the baffle matches the height of the water inside the reactor body.

[0063] The baffle extends vertically along the central axis of the reactor body and extends along the diameter of the circular bottom of the reactor body to the inner wall of the reactor body, and is fixedly installed on the inner wall of the reactor body; the top of the baffle is adapted to the liquid level inside the reactor body, that is, the height of the baffle is consistent with the liquid level inside the reactor body.

[0064] The baffle divides the reactor body into two relatively independent compartments: an anaerobic reaction chamber and a membrane separation chamber, which are symmetrically distributed on the left and right sides. The lower part of the baffle is fixed to the bottom of the reactor body and is sealed to the bottom contact surface.

[0065] The bottom of the baffle is fixedly installed on the bottom of the reactor body, and several elongated sludge return ports 10 are opened at the bottom of the baffle for returning the sludge settled in the membrane separation chamber to the anaerobic reaction chamber. This sludge return reduces energy consumption. The sludge return ports in this invention reduce the need for a dedicated sludge return pump, thus lowering costs.

[0066] The sludge return inlet is elongated (it can also be a round hole or any other shape), and the height of the sludge return inlet is 2cm-5cm. It should be arranged as densely as possible while meeting gravity load requirements. The sludge return inlet is located at the bottom of the sludge return plate at the bottom of the membrane separation chamber, allowing the sludge to settle to the bottom under gravity and then flow directly into the anaerobic reaction chamber from the sludge return inlet.

[0067] like Figure 1 , 23. Multiple water distribution pipes 18 are laid parallel to the bottom of the anaerobic reaction chamber 16. The water distribution pipes are parallel to the bottom of the baffle. The length of the water distribution pipes is adapted to the length of the chord of the circular bottom of the reactor body. Water distribution holes 3 are evenly arranged on each water distribution pipe. The water distribution pipes are connected to the water inlet pipe extending into the bottom of the anaerobic reaction chamber. The sewage outside the reactor body is introduced into the reactor body through the water inlet pipe 1 and the water is evenly distributed.

[0068] like Figure 1 , 3 A three-phase separator 5 and an oxidation-reduction potential detection electrode 6 are installed in the upper part of the anaerobic reaction chamber of the reactor body; wherein:

[0069] The oxidation-reduction potential (ORP) detection electrode 6 extends from the detection port into the anaerobic reaction chamber of the reactor body and is fixedly installed on the gas collection sealing cover through the detection port in a vertical position. The detection port is sealed. The upper end of the ORP detection electrode, i.e., one end of the connecting wire, is located outside the gas collection cover and is electrically connected to the automatic control system (i.e., the ORP online detector). The lower end (electrode sensor end) extends into the water inside the anaerobic reaction chamber 16 of the reactor body to measure the ORP of the water inside the reactor body. Furthermore, the lower end of the ORP detection electrode extends into the middle of the water in the anaerobic reaction chamber to measure the temperature and ORP of the water in the middle of the anaerobic reaction chamber.

[0070] In a specific embodiment of the present invention, the oxidation-reduction potential detection electrode used is an oxidation-reduction potential detection electrode with a temperature probe, which is used to measure the temperature and oxidation-reduction potential of the sewage sludge in the anaerobic reaction chamber of the reactor body and to monitor the microbial status.

[0071] In a specific embodiment of the present invention, the lower end of the oxidation-reduction potential detection electrode with a temperature probe extends into the water body below the bottom of the three-phase separator to monitor the oxidation-reduction potential of the water in the reactor body of the anaerobic membrane bioreactor of the present invention. The oxidation-reduction potential of the water can directly reflect the anaerobic conditions in the reaction zone of the reactor and indirectly reflect the growth status of microorganisms in the reactor.

[0072] The redox potential (RPP) value inside a reactor typically reflects the oxygen content of the water sample. Anaerobic reactions require extremely low oxygen levels. Generally, anaerobic reactors need an RRP below -330 mV; otherwise, the growth of methanogenic bacteria will be inhibited, affecting the biogas production of the reactor. The purpose of setting up an RRP detection electrode is to measure the RRP of the water sample.

[0073] The oxidation-reduction potential detection electrode in this embodiment of the invention is an oxidation-reduction potential detection electrode with a temperature probe. Other oxidation-reduction potential detection electrodes known in the art are also applicable to this invention.

[0074] The three-phase separator is installed on one side of the anaerobic reaction chamber, fixedly mounted on the baffle and the inner wall of the reactor body, with its installation height consistent with the liquid level inside the reactor body.

[0075] In this invention, the bottom inclination angle of the precipitator in the three-phase separator 5 should be relatively large, preferably 45° to 60°, and the average flow velocity of water through the liquid-solid separation pores should be maintained at 0-2 m / s. 3 ·m -2 ·h -1 .

[0076] The cylindrical sidewall of the reactor body has a sandwich structure, and the sandwich is filled with water for water bath heating or insulation. That is, the sidewall of the reactor body is equipped with a water bath sandwich to maintain the water temperature in the sandwich at 25-45℃, so as to ensure the anaerobic reaction temperature in the reactor.

[0077] In this specific embodiment of the invention, the anaerobic reaction occurring in the anaerobic reactor is illustrated using a mesophilic anaerobic reaction as an example. Anaerobic reactions at other temperatures are also applicable to this invention.

[0078] like Figure 2 , 3 A water inlet (not shown) is opened on the upper side wall of the bottom of the reactor body at the lower part of the reactor body. Wastewater is introduced into the reactor body through the water inlet, and the water inlet is sealed to the water inlet pipe.

[0079] The inlet pipe extends into the lower part of the anaerobic reaction chamber of the reactor body, above the bottom of the reactor body. The inlet pipe is perpendicular to the baffle 4. At least one water distribution pipe 18 is installed on the inlet pipe in a direction parallel to the baffle. The water distribution pipe is connected to the inlet pipe and has several water distribution holes 3 to distribute water evenly.

[0080] In a specific embodiment of the present invention, there are 4 water distribution pipes, and the length of the water distribution pipes is adapted to the length of the chord parallel to the diameter of the reactor body and the baffle.

[0081] The water distribution pipeline is designed according to the design method of a high-resistance water distribution system. The water distribution holes are small holes that face downwards or are inclined, with the flow velocity in the holes not less than 4 times the flow velocity at the pipe end, and the opening ratio is 0.2% to 0.25%. Both ends of the water distribution pipe are closed.

[0082] The wastewater is evenly distributed at the bottom of the reaction chamber through the water distribution holes. As the water flows upward from the bottom of the reactor, the sludge inside the reactor falls downward due to gravity, which also causes a change in the direction of the water flow in some areas, making the sludge and water mix more evenly.

[0083] After the anaerobic reaction, the mixed system in the anaerobic reactor is separated by a three-phase separator. The gas (biogas) flows upward, is collected in the gas collection and sealing hood, and flows out of the reactor body. The sludge after solid-liquid-gas separation is collected by the gas collection hood of the three-phase separator and sinks downward under its own weight and water flow, returning to the lower part of the anaerobic reactor to degrade organic matter. The water at the liquid surface in the anaerobic reactor flows out of the anaerobic reactor through the overflow weir of the three-phase separator and flows into the membrane separation chamber 17.

[0084] The membrane separation chamber 17 mainly plays a role in the final stage of effluent retention in the anaerobic membrane bioreactor, improving the quality of the effluent and reducing sludge loss.

[0085] The membrane separation chamber is equipped with membrane module 7, sludge return plate 9, and aeration assembly, wherein:

[0086] The membrane module is submerged below the liquid surface in the membrane separation chamber; the outlet of the membrane module is connected to the outlet pipe 8, and the effluent after membrane separation is discharged from the reactor through the outlet pipe.

[0087] The size of the membrane module is calculated based on the reactor's hydraulic residence time and flow rate; simply purchase a membrane module with a suitable membrane flux. The membrane module is installed on the inner wall of the reactor body below the liquid level and is fixed using hooks, supports, etc., and should be easily replaceable.

[0088] The sludge return plate is located below the membrane module and is inclined. Its bottom is fixedly installed at the bottom of the reactor body and is fixed together with the side of the baffle facing the membrane separation chamber. Its upper end is higher than the bottom and is inclined towards the anaerobic reaction chamber. The inclination angle with the bottom plane of the reactor is 60° (usually ≥45°, preferably 45-75°).

[0089] The sludge return plate is a semi-circular flat plate structure, which can be made of reinforced concrete or polypropylene. Its bottom is located at the bottom of the reactor body and abuts against the bottom of the baffle 4. Its arc-shaped outer edge is raised to fit tightly and seal against the inner wall of the reactor body. The length of the bottom of the sludge return plate matches the diameter of the reactor body, and the angle between the sludge return plate and the bottom plane of the reactor body is 60° (usually ≥45°, preferably 45-75°). Multiple through holes (not shown in the figure) are opened on the sludge return plate at positions corresponding to the membrane module above and below. That is, the through holes are located below the membrane module, usually directly below the membrane module. The aeration pipe of the aeration component passes through the through holes from the bottom of the sludge return plate upwards, enters the membrane separation chamber, and extends to the bottom of the membrane module. An aeration head 14 is installed at the top of the aeration pipe.

[0090] Figure 3 Double arrows indicate wastewater; single arrows indicate returned sludge; triple arrows indicate biogas.

[0091] The aeration pipe is sealed to prevent sludge and water from flowing into the space between the sludge return plate and the bottom of the reactor body within the membrane separation chamber.

[0092] The sludge return plate is secured or installed at the lower part of the membrane separation chamber of the reactor body by means of grooves opened along the inner wall of the reactor, or by means of a bracket set at the bottom of the reactor, so that the sludge return plate with a semi-circular structure is fixedly installed at the bottom of the reactor, and the angle between the sludge return plate and the bottom plane of the reactor body is 60° (usually ≥45°, preferably 45-75°).

[0093] The sludge in the membrane separation chamber settles naturally and is collected by the sludge return plate to the sludge return port of the baffle. It then flows back to the anaerobic reaction chamber through the sludge return port to continue the anaerobic reaction.

[0094] At the bottom of membrane separation chamber 17, a sludge return plate 9 is installed, inclined towards the sludge return port at the bottom of baffle 4. Sludge settled on the sludge return plate within the membrane separation chamber slides down to the sludge return port of the baffle under gravity, flowing into the anaerobic reaction chamber from there. Anaerobic microorganisms naturally settle from the membrane separation chamber and, utilizing the inclination angle of the sludge return plate, fall to the sludge return port. Under the action of the rising water flow in the anaerobic reaction chamber, the settled sludge from the sludge return port is carried into the reaction zone of the reaction chamber, re-participating in the anaerobic reaction and preventing clogging of the sludge return port.

[0095] like Figure 4 The aeration assembly, located below the membrane module, includes an air distribution pipe 21, an aeration pipe 22, and an aeration head 14. The air distribution pipe, in a T-shape, is positioned below the sludge return plate and lies flat at the bottom of the reactor body. The tail end of the T-shaped air distribution pipe is connected to the biogas return pipe 13 located outside the reactor body, and the end is fixedly connected to multiple aeration pipes 22. The number of aeration pipes corresponds to the number of through holes on the sludge return plate. An aeration head 14 is fixedly installed at the end of each aeration pipe. The aeration head is 0.5m (typically 0.5-1m) from the bottom of the membrane module.

[0096] Under the action of the vacuum biogas circulation pump 20, the biogas in the gas return pipe 13 is pressurized and distributed to each aeration pipe through the gas distribution pipe. Then, it is aerated through the aeration heads to form a large number of pressurized bubbles, which flush the membrane module above the aeration heads, clean the membrane fibers, and reduce membrane fouling. This invention utilizes the biogas generated by the reactor itself to flush the membrane module, which can improve energy utilization. The aerated biogas is collected again by the gas collection sealing cover and flows to the biogas storage tank through the exhaust pipe.

[0097] In the specific embodiments of the present invention, the membrane module is selected as a hollow fiber membrane. The membrane module 7 includes, but is not limited to, plate membranes and hollow fiber membranes.

[0098] One end of the water outlet pipe 8 of the membrane module is connected to the water outlet end of the membrane module, and the other end extends from the water outlet port on the gas collection sealing cover 11 and extends to the outside of the reactor body to discharge the purified water from the reactor. A drain valve 81 is provided on the water outlet pipe to facilitate stopping the membrane module when the reactor of the present invention is not working, or to facilitate the maintenance of the membrane module.

[0099] Gas continuously washes the membrane surface, causing the sludge adsorbed on the membrane surface to desorb under shear force, thus mitigating membrane fouling. The sludge return plate is tilted towards the anaerobic reaction chamber. Anaerobic microorganisms in the membrane separation chamber settle to the sludge return plate and naturally sink to the sludge return port 10 due to the tilt of the sludge return plate, and then flow back into the anaerobic reaction chamber from the sludge return port.

[0100] The working principle or workflow of the anaerobic bioreactor for mitigating membrane fouling of this invention is as follows:

[0101] After pretreatment, the wastewater enters the bottom of the anaerobic reaction chamber 15 of the anaerobic membrane bioreactor through the inlet pipe 1. Under the uniform water distribution effect of the water distribution pipes 18 evenly distributed at the bottom of the anaerobic reaction chamber and the water distribution holes 3 evenly arranged on them, the water flows evenly from bottom to top. Under the action of microorganisms within the anaerobic reaction chamber, an anaerobic reaction takes place (i.e., firstly, hydrolysis and acidification, where hydrolysis and acidification bacteria convert large molecules into smaller molecules; then, the hydrogen and acetic acid production stage, where hydrogen and acetic acid production bacteria convert the small molecules produced in the previous stage into hydrogen, acetic acid, etc.; finally, the methanogenic stage, where methanogenic bacteria utilize the products produced in the previous stage). The generated hydrogen and acetic acid are used to synthesize methane. The water then flows upwards through the three-phase separator 5 at the top of the anaerobic reaction chamber for three-phase separation. Solid sludge falls back, and the generated biogas (gas) is separated and collected at the gas collection sealing hood 11, discharged through the exhaust pipe, and stored in the biogas storage tank 12. Part of the biogas flows back to the membrane separation chamber of the membrane bioreactor through the gas return pipe, and the remaining biogas is purified for reuse or directly used as fuel. The separated water flows through the overflow weir of the three-phase separator and flows into the membrane separation chamber 17 from the top of the baffle 4. Under the action of the membrane module 7, the water is filtered by the membrane, and the effluent flows out of the membrane bioreactor from the effluent pipe.

[0102] The outer shell of the reactor body in the accompanying drawings of this invention is schematic and shown in perspective to facilitate the display of the internal structure.

[0103] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0104] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An anaerobic membrane bioreactor for mitigating membrane fouling, characterized in that, It includes the reactor body, the gas collection sealing hood, and the gas recovery-recirculation assembly, wherein: The main body of the reactor is used for anaerobic biological reaction and membrane separation of wastewater, wherein: The reactor body is cylindrical with a hollow interior and a sandwich structure on the side walls. The sandwich is filled with water for water bath heating or insulation, maintaining the water temperature in the sandwich at 25-45℃. It includes baffles installed inside the reactor body and anaerobic reaction chambers and membrane separation chambers located on both sides of the baffles. The baffles are set along the longitudinal section of the reactor body, dividing the reactor body into two relatively independent areas: the anaerobic reaction chamber and the membrane separation chamber. The bottom of the anaerobic reaction chamber is filled with activated sludge. After the wastewater enters the anaerobic reaction chamber, it mixes with the activated sludge to carry out the anaerobic reaction. The bottom of the baffles is fixedly installed on the bottom of the reactor body, and several long strip-shaped sludge return ports are opened at the bottom of the baffles to return the sludge settled in the membrane separation chamber to the anaerobic reaction chamber. Furthermore, a three-phase separator and an oxidation-reduction potential detection electrode are installed at the top of the anaerobic reaction chamber, wherein: The oxidation-reduction potential detection electrode extends from the detection port of the gas collection sealing cover into the anaerobic reaction chamber of the reactor body to measure the temperature and oxidation-reduction potential of the water inside the anaerobic reaction chamber and monitor the growth status of microorganisms inside the anaerobic reaction chamber. The three-phase separator is fixedly installed at the liquid surface inside the anaerobic reactor body, and the bottom inclination angle of the sedimentation tank of the three-phase separator is 45-60°. After the anaerobic reaction, the mixed system is separated by the three-phase separator. The gas flows upward, is collected in the gas collection hood, and then flows out of the reactor body. The sludge after solid-liquid-gas separation is collected by the gas collection hood of the three-phase separator and sinks downward under its own weight and the action of water flow, returning to the lower part of the anaerobic reaction chamber to degrade organic matter. The water at the liquid surface of the anaerobic reaction chamber flows out of the anaerobic reaction chamber through the overflow weir of the three-phase separator and flows into the membrane separation chamber. The supernatant from the anaerobic reaction flows into the membrane separation chamber, which contains membrane modules, a sludge return plate, and an aeration assembly. Water is produced through membrane separation by the membrane modules within the chamber. The membrane module is submerged below the liquid surface in the membrane separation chamber. The outlet of the membrane module is connected to the outlet pipe, and the water after membrane separation is discharged from the reactor through the outlet pipe. The sludge return plate is located below the membrane module and is inclined. Its bottom is fixedly installed at the bottom of the reactor body and is fixed together with the side of the baffle facing the membrane separation chamber. Its upper end is higher than the bottom and is inclined towards the anaerobic reaction chamber. The aeration unit is located below the membrane module and includes an air distribution pipe, an aeration pipe, and an aeration head. The gas generated by the aeration head washes over the membrane module, cleans the membrane fibers, and reduces membrane fouling. The gas collection sealing cover is used to collect the biogas produced by the anaerobic reaction inside the reactor body and discharge the biogas to the gas recovery-recirculation assembly outside the reactor body; The gas recovery-recirculation assembly is located outside the reactor body and is fixedly connected to the top of the gas collection sealing hood. It is used to store the biogas collected by the gas collection sealing hood and to return a portion of the biogas to the inside of the reactor body to flush the membrane module inside the reactor body that performs membrane separation.

2. The anaerobic membrane bioreactor as described in claim 1, characterized in that, The gas collecting sealing cover is conical or inverted funnel-shaped, and the shape and size of its bottom match the shape and size of the top of the reactor body.

3. The anaerobic membrane bioreactor as described in claim 1 or 2, characterized in that, The gas collection sealing cover is provided with an exhaust port, a detection port, and a water outlet. The exhaust port is connected to the gas recovery-recirculation component; the detection port is used to fix and install the oxidation-reduction potential detection electrode; and the water outlet is used to fix and install the water outlet pipe from which the purified water flows out after membrane separation in the reactor body.

4. The anaerobic membrane bioreactor as described in claim 1 or 2, characterized in that, The gas recovery-recirculation assembly includes an exhaust pipe, a biogas storage tank, a gas return pipe, and a biogas circulation pump. One end of the exhaust pipe is sealed to a gas collection sealing cover, and the other end is connected to the biogas storage tank mounted on the exhaust pipe. One end of the gas return pipe is connected to the biogas storage tank, and the other end is connected to a gas distribution pipe located at the bottom of the reactor body, returning a portion of the biogas stored in the biogas storage tank to the reactor body. The biogas circulation pump is mounted on the gas return pipe and is used to pressurize the biogas returning to the reactor body, ensuring the returned biogas has a certain pressure.

5. The anaerobic membrane bioreactor as described in claim 1, characterized in that, The air distribution pipe is located below the sludge return plate and is T-shaped. Its tail end is connected to the biogas return pipe located outside the reactor body and is fixedly connected to multiple aeration pipes. An aeration head is fixedly installed at the end of the aeration pipe.

6. The anaerobic membrane bioreactor as described in claim 1, characterized in that, The sludge return plate is a semi-circular flat plate with multiple through holes at positions corresponding to the membrane module. The aeration pipe of the aeration module passes through the through holes from the bottom of the sludge return plate upwards, extends into the membrane separation chamber, and extends to the bottom of the membrane module.

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