Anaerobic membrane bioreactor for treating kitchen waste with high solid content and operation method

Abstract

The invention provides an anaerobic membrane bioreactor for high-solid-content kitchen waste treatment and an operation method, and belongs to the technical field of waste treatment equipment.The anaerobic membrane bioreactor is characterized in that an anaerobic digestion tank is communicated with the head end of a membrane assembly through an ultrafiltration circulating pump; the tail end of the membrane component is used for discharging the produced concentrated liquid into the anaerobic digestion tank through a sludge discharge pump; and the anaerobic digestion tank pumps the produced biogas into the bottom aeration device through a gas reflux pump, and pumps the top biogas slurry into the bottom rotational flow water distribution port through a biogas slurry reflux pump. The tubular ultrafiltration membrane tube with a rifling structure is adopted, mud cakes on the inner surface of the membrane tube are scoured by strengthening disturbance of internal water flow, and the membrane blocking phenomenon is further avoided in a mode of adding rigid magnetic powder; the use of the magnetic powder can effectively improve the composition of functional microbial communities and the electron transfer efficiency, and with the assistance of the increase of the functional microbial biomass brought by the ultrafiltration membrane, the effective increase of the anaerobic digestion organic load of a kitchen waste treatment system can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of garbage treatment equipment, and in particular to an anaerobic membrane bioreactor for treating high-solid content kitchen garbage and an operation method thereof. Background Art

[0002] Food waste contains a large amount of protein, carbohydrates, oil, cellulose, etc. These organic substances have good biodegradability. Studies have found that the content of organic matter can reach 95-98% of the dry matter content, which shows that food waste has a high potential for energy recovery.

[0003] Anaerobic digestion is a good way to extract chemical energy from food waste. However, in order to ensure stable operation, the hydraulic retention time (HRT) used in traditional anaerobic digestion is ≥30 days, which leads to the low ability of the process to treat food waste, and the organic load is only 0.8-2kg COD / (m3d). If the HRT is blindly reduced, the methanogens with slower growth rates will be lost, making the anaerobic fermentation acid production and methanogenesis stage reactions more unbalanced under high organic load, and volatile acid accumulation is prone to occur, leading to system rancidity. In addition, food waste has extremely high COD and particulate matter concentrations, and it is difficult to completely remove them through anaerobic digestion, resulting in COD in the biogas slurry as high as 15,000-25,000 mg / L and TS of about 2-3%. Therefore, the anaerobic effluent with mud must first be separated from the mud and water by flotation or centrifugation before entering the aerobic treatment, resulting in complicated treatment processes and other problems.

[0004] Although the introduction of anaerobic membrane bioreactor can effectively solve the problem of solid-liquid separation and increase the sludge retention time in the anaerobic tank. However, the membrane flux in the reactor will continue to decrease as the device operates, and the transmembrane pressure difference of the membrane assembly will continue to increase (until >30kPa), resulting in the need for frequent cleaning or replacement of the membrane assembly, which results in high operating costs and seriously affects the treatment effect. In addition, the effect of anaerobic membrane bioreactors in increasing organic load by increasing sludge concentration is very limited, and is often accompanied by the problem of volatile acid accumulation. It is necessary to use more efficient functional microbial community composition and electron transfer methods to change the efficiency of anaerobic digestion. In addition, due to the reaction characteristics of anaerobic digestion, the acid production process in the anaerobic tank will cause corrosion of the agitator, resulting in damage to the impeller due to its inability to cope with high mechanical stress in a high solid content environment.

[0005] At present, the waste treatment method for kitchen waste with a high solid content is mostly to directly perform anaerobic digestion after crushing, pulping, and oil extraction to extract as much carbon and energy as possible. The anaerobic digestion reactor used is a fully mixed anaerobic reactor (CSTR), and a large-torque mechanical stirring paddle is used for direct mixing to ensure that the functional microorganisms and the substrate are fully mixed. The high liquid viscosity in the system causes the stirring paddle to be subjected to greater mechanical stress, and the acid produced during the anaerobic digestion process will gradually corrode the stirring paddle, resulting in a high equipment failure rate, difficult maintenance, and high operating costs. Therefore, mixing is performed by providing a higher liquid rising flow rate. However, the disturbance provided by this method is very limited, especially when the solid content of the original liquid is high, it is difficult to achieve a stirring effect.

[0006] Similarly, due to the high solid content in the food waste system, the existing biogas slurry treatment process is extremely dependent on the pre-efficient solid-liquid separation technology, and it is necessary to reduce the suspended matter content in the biogas slurry before denitrification and carbon removal to avoid impact on the subsequent biochemical system. Currently, the more commonly used methods are flotation, flocculation sedimentation, centrifugal solid-liquid separators, etc., all of which lead to high operating costs. Although some patents use anaerobic membrane bioreactors with external tubular ultrafiltration membranes to achieve solid-liquid separation, the membrane blockage problem is very serious during actual use in the food waste treatment industry. Summary of the invention

[0007] The object of the present invention is to provide an anaerobic membrane bioreactor for treating high-solid content food waste and an operation method thereof, so as to solve at least one technical problem existing in the above-mentioned background technology.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] On the one hand, the present invention provides an anaerobic membrane bioreactor for treating high-solid content food waste, comprising: a raw liquid collection tank for collecting raw liquid from food waste, and an anaerobic digestion tank connected to the raw liquid collection tank; the anaerobic digestion tank is connected to the head end of a membrane assembly through an ultrafiltration circulation pump; the end of the membrane assembly discharges part of the concentrated liquid produced by the membrane assembly into the anaerobic digestion tank through a mud discharge pump; wherein the anaerobic digestion tank pumps the produced biogas into a bottom aeration device through a gas reflux pump, and pumps the top biogas into a bottom swirl water distribution outlet through a biogas reflux pump.

[0010] Furthermore, the biogas residue produced by the anaerobic digestion tank is discharged to the magnetic powder recovery unit through the biogas residue discharge pump, the magnetic powder after magnetization recovery re-enters the anaerobic digestion tank, and the remaining biogas residue enters the sludge dewatering system.

[0011] Furthermore, the anaerobic digestion tank is connected to the ultrafiltration circulation pump via a biogas slurry discharge pump.

[0012] Furthermore, the membrane assembly is an external tubular membrane assembly, using an ultrafiltration membrane with an inner diameter of 5 mm and a pore size of 30 nm, and having internal rifling with an angle of 30° and a spacing of 1 cm to enhance turbulence in the membrane tube.

[0013] Furthermore, the water produced by the membrane assembly is collected by an external casing and then discharged to a biogas slurry regulating tank via a drainage pump for subsequent biogas slurry treatment.

[0014] Furthermore, the ultrafiltration circulation pump is connected to the dosing and cleaning barrel via a cleaning pump, and the end of the membrane assembly is connected to the dosing and cleaning barrel via a drainage pump.

[0015] Furthermore, the chemical-adding cleaning barrel is connected to a plurality of cleaning liquid storage barrels.

[0016] In a second aspect, the present invention provides an operation method of an anaerobic membrane bioreactor for treating high-solid content kitchen waste, wherein: the anaerobic digester pumps the biogas produced in the anaerobic tank into a bottom aeration device through a gas reflux pump, and pumps the top biogas into a bottom swirl water distribution outlet through a biogas reflux pump, so as to achieve a biogas reflux ratio of 1:20; magnetic powder is added to the anaerobic digester to change the enzyme activity and community composition of functional microorganisms by promoting extracellular electron transfer;

[0017] Part of the biogas produced by the anaerobic digester is used to provide disturbance inside through a gas reflux pump, and the other part is discharged to a biogas treatment system for subsequent dehydration treatment. The produced biogas residue is discharged to a magnetic powder recovery unit through a biogas residue discharge pump. The magnetic powder after magnetization recovery re-enters the anaerobic digester through a feed pump, and the remaining biogas residue enters a sludge dehydration system.

[0018] The biogas slurry is discharged through the biogas slurry external discharge pump, and is mixed with the reflux stock liquid in the membrane assembly in the ultrafiltration circulation pump and then injected into the membrane assembly together. When the parameters are adjusted according to the operating effect of the digester, the biogas slurry properties may fluctuate, and the stable operation of the external tubular membrane assembly 5 can be achieved when the suspended matter content in the biogas slurry is within 45g / L.

[0019] Furthermore, the temperature of the membrane assembly during operation is 30-38°C, the maximum pressure is no higher than 0.8 MPa, and the produced water is collected by an external casing and then discharged to a biogas slurry regulating tank through a drainage pump for subsequent biogas slurry treatment.

[0020] Furthermore, the hydraulic retention time of the anaerobic digester is 25 to 30 days, the operating temperature is 32 to 34° C., the operating pH is maintained between 7.0 and 7.7, the magnetic powder content is maintained at 3 to 5%, and the load can achieve 6 to 8 kg COD / (m3d).

[0021] The invention has the following beneficial effects: a tubular ultrafiltration membrane tube with a rifling structure is used to flush the mud cake on the inner surface of the membrane tube by strengthening the disturbance of the internal water flow, and the occurrence of membrane blockage is further avoided by adding rigid magnetic powder. The use of magnetic powder can effectively improve the composition of functional microbial communities and the efficiency of electron transfer, and with the increase in the amount of functional microorganisms brought by the ultrafiltration membrane, the anaerobic digestion organic load of the food waste treatment system can be effectively improved.

[0022] Additional aspects and advantages of the present invention will be given in part in the following description, which will become obvious from the following description, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0024] Figure 1 This is a structural diagram of an anaerobic membrane bioreactor for treating high-solid content food waste according to an embodiment of the present invention.

[0025] Figure 2 This is a bottom structural diagram of an anaerobic digestion tank of an anaerobic membrane bioreactor for treating high-solid content food waste according to an embodiment of the present invention.

[0026] Figure 3 This is a structural diagram of the membrane tubes of the membrane assembly of the anaerobic membrane bioreactor for treating high-solid content food waste according to an embodiment of the present invention.

[0027] Among them: 1-food waste raw liquid; 2-raw liquid collection tank; 3-anaerobic digestion tank; 4-ultrafiltration circulation pump; 5-membrane assembly; 6-dosing cleaning barrel; 7-acid storage barrel; 8-alkali storage barrel; 9-cleaning liquid barrel; 10-magnetic powder recovery unit; 11-biogas treatment system; 12-biogas slurry regulating tank; 13-feed pump; 14-gas reflux pump; 15-biogas slurry reflux pump; 16-biogas slurry external discharge pump; 17-sludge pump; 18-biogas residue discharge pump; 19-discharge pump; 20-cleaning pump; 21-discharge pump; 22-drainage pump; 23-acid pump; 24-alkali pump; 25-cleaning liquid pump; 26-sludge dewatering system. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below by the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0029] It should be understood by those skilled in the art that unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs.

[0030] It should also be understood that terms, such as those defined in commonly used dictionaries, should be understood to have a meaning consistent with that in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless as defined herein.

[0031] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or groups thereof.

[0032] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0033] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0034] In the description of this specification, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present technology and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present technology.

[0035] Unless otherwise clearly specified or limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected or set, or detachably connected or set, or integrally connected or set. For ordinary technicians in this field, the specific meanings of the above terms in this technology can be understood according to specific circumstances.

[0036] To facilitate understanding of the present invention, the present invention is further explained below with reference to specific embodiments in conjunction with the accompanying drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0037] Those skilled in the art should understand that the drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily necessary for implementing the present invention.

[0038] The present invention adopts a tubular ultrafiltration membrane tube with a rifling structure, and realizes the flushing of the mud cake on the inner surface of the membrane tube by strengthening the disturbance of the internal water flow, and further avoids the occurrence of membrane blocking by adding rigid magnetic powder. The use of magnetic powder can effectively improve the composition of functional microbial communities and the efficiency of electron transfer, and with the improvement of the amount of functional microorganisms brought by the ultrafiltration membrane, it can effectively improve the anaerobic digestion organic load of the kitchen waste treatment system. The present invention uses reflux biogas for aeration, uses the rising disturbance of gas instead of mechanical stirring for mixing, and performs a 1:20 slurry reflux through a cyclone water distributor to avoid gas-liquid short-circuiting, which can effectively achieve the stirring effect while avoiding the occurrence of equipment failure.

[0039] Example

[0040] like Figure 1 As shown, in this embodiment, an anaerobic membrane bioreactor for treating high-solid content food waste is provided, comprising: a raw liquid collection pool 2 for collecting raw liquid 1 of food waste, and an anaerobic digestion tank 3 connected to the raw liquid collection pool 2; the anaerobic digestion tank 3 is connected to the head end of the membrane assembly 5 through an ultrafiltration circulation pump 4; the end of the membrane assembly 5 discharges part of the concentrated liquid produced by the membrane assembly 5 into the anaerobic digestion tank 3 through a mud discharge pump 17; wherein the anaerobic digestion tank 3 pumps the produced biogas into the bottom aeration device through a gas reflux pump 14, and pumps the top biogas into the bottom swirl water distribution outlet through a biogas reflux pump 15.

[0041] The sludge produced by the anaerobic digestion tank 3 is discharged to the magnetic powder recovery unit 10 through the sludge discharge pump 18, and the magnetic powder after magnetization recovery re-enters the anaerobic digestion tank 3, and the remaining sludge enters the sludge dewatering system 26. The water produced by the membrane module 5 is collected by the external casing and discharged to the biogas slurry regulating tank 12 through the drainage pump 22 for subsequent biogas slurry treatment. The ultrafiltration circulation pump 4 is connected to the dosing cleaning barrel 6 through the cleaning pump 20, and the end of the membrane module 5 is connected to the dosing cleaning barrel 6 through the drainage pump 21.

[0042] The dosing cleaning barrel 6 is connected to a plurality of cleaning solution storage barrels, such as an acid storage barrel 7, an alkali storage barrel 8 and a cleaning solution barrel 9, respectively.

[0043] In this embodiment, the operation method of the anaerobic membrane bioreactor for treating high solid content food waste comprises the following steps:

[0044] After screening, pulping, dilution and oil extraction, the restaurant kitchen waste liquid 1 enters the liquid collection tank 2 so as to provide a stable feed for the anaerobic digestion tank 3 through the feed pump 13. The solid content of the restaurant kitchen waste liquid 1 in the collection tank 2 is 5-8%, and the chemical oxygen demand (COD) is 70000-80000 mg / L.

[0045] The anaerobic digestion tank 3 adopts a gas-water mixing method, and the biogas produced in the anaerobic tank is pumped into the bottom aeration device through the gas reflux pump 14, thereby providing disturbance for the food waste raw liquid therein, and the top biogas is pumped into the bottom swirl water distribution outlet through the biogas reflux pump 15. Figure 2 As shown, a 1:20 biogas slurry return ratio is achieved, providing an upward flow rate for the mixed liquid in the anaerobic tank and generating a swirl flow, avoiding the occurrence of gas-liquid short-circuiting phenomenon, and achieving sufficient mixing of anaerobic digestion sludge and substrate. In addition, magnetic powder (100-120 mesh, particle size 180-150 μm) is added to the anaerobic tank to change its enzyme activity and community composition by promoting the extracellular electron transfer of functional microorganisms, thereby avoiding organic acid inhibition and increasing organic load. The hydraulic retention time of the anaerobic tank 3 is 25 to 30 days, the operating temperature is 32 to 34°C, the operating pH is maintained between 7.0 and 7.7, the magnetic powder content is maintained at 3 to 5% (mixed and supplemented with the feed when loss occurs), and the load can achieve 6 to 8 kg COD / (m3d);

[0046] Part of the biogas produced by the anaerobic digester 3 is used to provide disturbance inside through the gas reflux pump 14, and the other part is discharged to the biogas treatment system 11 for subsequent desulfurization and other operations. The produced biogas residue is discharged to the magnetic powder recovery unit 10 through the biogas residue discharge pump 18. The magnetic powder after magnetization recovery re-enters the digester through the feed pump 13, and the remaining biogas residue enters the sludge dewatering system 26;

[0047] The biogas slurry is discharged through the biogas slurry external discharge pump 16, and is mixed with the reflux stock solution in the membrane module 5 in the ultrafiltration circulation pump 4 and then pumped into the membrane module 5 together. When the parameters are adjusted according to the operation effect of the digester, the biogas slurry properties may fluctuate, and the content of suspended matter in the biogas slurry within 45g / L can achieve stable operation of the external tubular membrane module 5;

[0048] The external tubular membrane assembly 5 uses an ultrafiltration membrane with an inner diameter of 5 mm and a pore size of 30 nm, and has internal rifling with an angle of 30° and a spacing of 1 cm to enhance the turbulence in the membrane tube (e.g. Figure 3 At the same time, the rigid magnetic powder in the biogas slurry will also strengthen the scouring of the mud cake, so the internal liquid flow rate is maintained at about 20m3 / h during operation to avoid membrane blockage; during operation, the temperature of the membrane assembly 5 is 30-38°C, and the maximum pressure is not higher than 0.8mpa. The produced water is collected by the external casing and discharged to the biogas slurry regulating tank 12 through the drainage pump 22 for subsequent biogas slurry treatment;

[0049] When the pressure in the membrane tube is high, part of the concentrated liquid produced by the membrane assembly 5 can be discharged to the digester 3 through the sludge pump 17 to maintain a high sludge concentration in the digester and maintain the residence time of the retained large organic particles in the digester, thereby increasing the organic load.

[0050] When the membrane tube is slightly blocked, that is, when the pressure in the membrane assembly 5 is still difficult to reduce after the sludge pump 17 discharges sludge, an appropriate flushing process is required, and the flushing process is about once a month. When the equipment is running, the corresponding reagents must be kept in the acid storage tank 7, the alkali storage tank 8 and the cleaning liquid tank 9. When the membrane is blocked, the biogas slurry external discharge pump 16 and the sludge pump 17 must be turned off first to prevent the cleaning liquid from entering the digester. Subsequently, after being mixed and diluted in the dosing cleaning barrel 6 by the acid pump 23, the alkali pump 24 and the cleaning liquid pump 25, it is added to the membrane assembly through the cleaning pump 20, and the flow rate is provided by the ultrafiltration circulation pump 4 to clean the membrane assembly. After cleaning, the liquid returns to the dosing cleaning barrel 6 through the drainage pump 21 for recycling. After the pressure of the membrane assembly 5 returns to normal, the sewage in the dosing cleaning barrel 6 is discharged to the regulating tank 12, and is subsequently treated with the sewage treatment system.

[0051] The cleaning steps are as follows: First, the reagents in the acid storage tank 7 and the cleaning liquid tank 9 are mixed and added into the dosing cleaning tank 6. After mixing and dilution, the pH in the dosing cleaning tank 6 is maintained in the range of 1.8 to 2.5, and after heating to a temperature close to that of the membrane module 5, the cleaning pump 20 is turned on for the acid cleaning process, and the pressure of the module is monitored to see if it is normal. After the acid cleaning operation for 30 minutes, the cleaning pump 20 is turned off, and the dosing cleaning tank 6 is emptied; if the pressure of the membrane module is restored, the reagents in the cleaning liquid tank 9 are added into the dosing cleaning tank 6, and diluted. After the release, open the cleaning pump 20 to flush and maintain the membrane assembly. After running for 15 minutes, the cleaning pump 20 and the drainage pump 21 can be turned off, and the system can be restored to use; if the pressure of the membrane assembly is still high after acid washing, the medicines in the alkali storage barrel 8 and the cleaning liquid barrel 9 are mixed and put into the dosing cleaning barrel 6. After mixing and dilution, the pH in the dosing cleaning barrel 6 is maintained in the range of 11.5 to 12.5, and the acid washing operation is repeated for alkali washing. After the alkali washing is completed, the membrane assembly needs to be flushed and maintained after the medicines in the cleaning liquid barrel 9 are diluted.

[0052] When the membrane tube needs to be replaced, that is, a certain membrane tube in the membrane assembly 5 leaks, or the flushing process still cannot reduce the pressure in the membrane tube, the corresponding membrane tube needs to be replaced. At this time, the feed pump 13, the biogas slurry discharge pump 16 and the mud pump 17 can be stopped, and the drainage pump 21 can be turned on to drain the liquid in the membrane tube, and then the corresponding blocked section in the membrane assembly 5 can be replaced. The drainage and membrane assembly replacement process can be completed within 20 minutes. The life of the membrane assembly is 5 to 10 years.

[0053] When the anaerobic tank fails, that is, equipment failure, damage or internal environmental imbalance occurs and sludge discharge maintenance is required, the feed pump 13, gas return pump 14, biogas slurry return pump 15, biogas slurry external discharge pump 16 and sludge pump 17 need to be closed, and the discharge pump 19 is opened to discharge the sludge and garbage raw liquid in the digester 3, and the bottom biogas residue is discharged through the biogas residue discharge pump 18.

[0054] In summary, the anaerobic membrane bioreactor and operation method for treating high-solid content food waste proposed in the embodiments of the present invention utilizes the method of reflux gas lift in the biogas in the anaerobic tank to replace the mechanical stirring equipment to achieve the mixing and disturbance of the stock solution, and eliminates the dead corners in the digester tank by the vortex flow of the reflux biogas to achieve complete mixing; and utilizes a tubular ultrafiltration membrane with built-in rifling as a membrane component, and the turbulent flow generated by the water flowing through the rifling flushes the mud cake, thereby achieving solid-liquid separation of the food waste biogas with a high solid content; at the same time, the functional microbial community composition and the electron transfer mode in the digester are changed by the addition of magnetic powder, thereby effectively improving the organic load of anaerobic digestion.

[0055] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative work on the basis of the technical solution disclosed in the present invention should be included in the scope of protection of the present invention.

Claims

1. An anaerobic membrane bioreactor for treating high-solid content kitchen waste, characterized in that: include: A raw liquid collection tank (2) for collecting raw liquid from kitchen waste, and an anaerobic digestion tank (3) connected to the raw liquid collection tank (2); the anaerobic digestion tank (3) is connected to the head end of a membrane module (5) via an ultrafiltration circulation pump (4); the tail end of the membrane module (5) discharges part of the concentrated liquid produced by the membrane module (5) into the anaerobic digestion tank (3) via a mud discharge pump (17); wherein the anaerobic digestion tank (3) pumps the produced biogas into a bottom aeration device via a gas reflux pump (14), and pumps the top biogas into a bottom swirl water distribution outlet via a biogas reflux pump (15).

2. The anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 1, characterized in that: The biogas residue produced by the anaerobic digestion tank (3) is discharged to the magnetic powder recovery unit (10) through the biogas residue discharge pump (18), the magnetic powder recovered by magnetization re-enters the anaerobic digestion tank (3), and the remaining biogas residue enters the sludge dewatering system (26).

3. The anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 1, characterized in that: The anaerobic digestion tank (3) is connected to the ultrafiltration circulation pump (4) via a biogas slurry discharge pump (16).

4. The anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 1, characterized in that: The membrane assembly (5) is an external tubular membrane assembly, using an ultrafiltration membrane with an inner diameter of 5 mm and a pore size of 30 nm, and having internal rifling with an angle of 30° and a spacing of 1 cm to enhance turbulence in the membrane tube.

5. The anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 4, characterized in that: The water produced by the membrane assembly (5) is collected by an external casing and then discharged to a biogas slurry regulating tank (12) via a drainage pump (22) for subsequent biogas slurry treatment.

6. The anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 1, characterized in that: The ultrafiltration circulation pump (4) is connected to the dosing and cleaning barrel (6) via a cleaning pump (20), and the end of the membrane assembly (5) is connected to the dosing and cleaning barrel (6) via a drainage pump (21).

7. The anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 6, characterized in that: The dosing cleaning barrel (6) is connected to a plurality of cleaning liquid storage barrels.

8. An operating method of an anaerobic membrane bioreactor for treating high-solid content food waste, characterized in that: The anaerobic digestion tank (3) pumps the biogas produced in the anaerobic tank into the bottom aeration device through the gas reflux pump (14), and pumps the top biogas into the bottom swirl water distribution outlet through the biogas reflux pump (15), so as to achieve a biogas reflux ratio of 1:20; magnetic powder is added to the anaerobic digestion tank (3) to change the enzyme activity and community composition of functional microorganisms by promoting the extracellular electron transfer of the functional microorganisms; A portion of the biogas produced by the anaerobic digestion tank (3) is used to provide internal disturbance through a gas reflux pump (14), and the other portion is discharged to a biogas treatment system (11) for subsequent degassing. The produced biogas residue is discharged to a magnetic powder recovery unit (10) through a biogas residue discharge pump (18). The magnetic powder recovered by magnetization re-enters the anaerobic digestion tank (3) through a feed pump (13), and the remaining biogas residue enters a sludge dewatering system (16); The biogas slurry is discharged through the biogas slurry external discharge pump (16), and is mixed with the reflux stock solution in the membrane assembly (5) in the ultrafiltration circulation pump (4) and then pumped into the membrane assembly (5) together. When the parameters are adjusted according to the operating effect of the digester, the biogas slurry properties may fluctuate. However, when the suspended matter content in the biogas slurry is within 45 g / L, the external tubular membrane assembly 5 can achieve stable operation.

9. The method for operating the anaerobic membrane bioreactor for treating high-solid content kitchen waste according to claim 8, characterized in that: The temperature of the membrane assembly (5) during operation is 30-38° C., and the maximum pressure is no higher than 0.8 MPa. The produced water is collected by an external casing and then discharged to the biogas slurry regulating tank (12) through a drainage pump (22) for subsequent biogas slurry treatment.

10. The method for operating the anaerobic membrane bioreactor for treating high-solid content food waste according to claim 8, characterized in that: The hydraulic retention time of the anaerobic digestion tank (3) is 25 to 30 days, the operating temperature is 32 to 34°C, the operating pH is maintained between 7.0 and 7.7, the magnetic powder content is maintained at 3 to 5%, and the load can achieve 6 to 8 kg COD / (m3d).

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