Method for comprehensive wet separation of anaerobic fermentation residues

Abstract

The present application relates to a kind of anaerobic fermentation biogas residue wet comprehensive separation method, comprising the following steps: (1) anaerobic fermentation biogas residue is diluted in turn using biogas slurry and / or sewage, then centrifugal separation, remove the impurities of particle size >10mm, liquid phase is separated once, and then separated for the second time, and the liquid phase containing organic components is obtained;(2) the liquid phase containing organic components, sludge of sewage treatment system is sent into conditioning tank, and wood and the like are added for conditioning, then dewatering by filter pressing, and the dewatering cake is obtained;(3) the dewatering cake is crushed and sent into rotten aging tank for rotten aging.The present application can fully resource utilization of most solid components in biogas residue by wet comprehensive separation of anaerobic fermentation biogas residue, solve the bottleneck problem that anaerobic fermentation biogas residue is difficult to resource utilization at present, and greatly improve the resource utilization rate and reduction rate of household garbage / kitchen garbage treatment technology based on anaerobic fermentation process.

Description

Technical Field

[0001] This invention belongs to the field of biogas residue resource utilization technology, and relates to a method for wet comprehensive sorting of anaerobic fermentation biogas residue. Background Technology

[0002] Anaerobic fermentation is an economical and efficient method for the harmless and resource-based treatment of urban and rural organic solid waste. It can anaerobically digest most organic matter and produce biogas. The biogas concentration produced by anaerobic fermentation can usually reach about 60%, and the biogas purification and power generation / purification technology is relatively mature. However, 20-30% of the organic components in the biogas residue and slurry usually cannot be fully degraded in the anaerobic fermentation process. In most cases, after dehydration, the biogas residue and slurry, with a water content of 70%-80%, are sent to landfills or co-processed in municipal solid waste incinerators. The overall volume reduction rate of anaerobic fermentation is relatively low, relying on incineration / landfill as a last resort. In recent years, there have been numerous explorations and applications of resource utilization for biogas residue, among which composting using the organic components in biogas residue is a widely studied technical route.

[0003] However, all types of waste, including food waste, kitchen waste, and household waste, contain impurities such as plastics, glass and ceramics, ash, paper, and wood and bamboo. Incompletely sorted food waste and household waste may also contain waste textiles. After pretreatment screening / pulping / sorting, textiles, plastics, and glass and ceramics are shredded. During pretreatment, most impurities are separated, but 15-20% are still shredded and mixed into the organic slurry. For wet anaerobic digesters, the material concentration in the tank is low, generally 1-2%. Most of the shredded fibers and plastic fragments are discharged as scum, while ash and broken glass and ceramics are discharged as sediment. However, some fibrous impurities remain suspended in the tank and are discharged with the biogas residue. For dry anaerobic digesters, the discharge concentration is usually above 15%, making it difficult to effectively remove these impurities. Thorough impurity removal of the biogas residue is necessary; otherwise, the quality of the product cannot be guaranteed, affecting the achievement of the overall resource recovery goal. For biogas residue treatment, most studies focus on improving solid-liquid separation efficiency, increasing the solid content of the solid phase, and postponing the process of removing impurities from biogas residue, removing impurities only after the residue has been fully decomposed and aged.

[0004] After composting and aging, it becomes even more difficult to separate the broken plastic pieces from the organic components, and it is also more difficult to separate the fine glass and ceramic fragments from the organic matter. This seriously restricts the resource utilization of anaerobic fermentation biogas residue.

[0005] Chinese patent application CN202310929674.9 discloses a method for the refined utilization and full-scale disposal of organic components in kitchen waste. Targeting the different organic components separated from kitchen waste, it constructs an integrated technical system encompassing efficient dry anaerobic fermentation of easily decomposable organic solid residue, ultra-high temperature aerobic composting of easily decomposable organic solid residue, and efficient wet anaerobic digestion of organic slurry. This forms a technical method for the refined utilization of the solid and liquid components of kitchen waste, achieving refined and efficient utilization and full-scale disposal of these components, providing technical support for kitchen waste disposal. However, this technology has high requirements for the raw materials processed. Typically, kitchen waste / household waste contains a certain amount of impurities such as glass, ceramics, paper, wood, bamboo, plastics, and textiles. During mechanical sorting, these impurities are crushed and ground into broken glass and fine fibers, ultimately entering soil conditioners / nutrient soil. This results in excessive impurities in the product, severely restricting the application scenarios of resource-based products, thus preventing the anaerobic fermentation residue from truly achieving resource utilization. Summary of the Invention

[0006] The purpose of this invention is to provide a method for wet comprehensive sorting of anaerobic fermentation biogas residue, which can realize the full resource utilization of biogas residue and solve the bottleneck problems in the resource utilization of anaerobic fermentation biogas residue.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for wet comprehensive separation of anaerobic fermentation biogas residue includes the following steps:

[0009] (1) The anaerobic fermentation biogas residue of kitchen waste and / or domestic waste is diluted and centrifuged in sequence to remove impurities with a particle size >10mm. The resulting liquid phase is then subjected to a first sand removal separation and a second fiber debris removal treatment to obtain a liquid phase containing organic components.

[0010] (2) The liquid phase containing organic components and the sludge generated by the sewage treatment system are fed into the conditioning tank together, and a conditioning agent is added. Then, the mixture is dewatered by pressure filtration to obtain dewatered cake.

[0011] (3) After the dewatered soil cake is crushed, it is sent to the composting and aging tank for composting and aging to obtain the nutrient soil product.

[0012] (4) The heavy inert component obtained after the first sand removal and separation in step (1) is further washed with water to obtain the gravel product;

[0013] (5) The impurity components obtained after centrifugation in step (1) and the fiber debris components obtained after secondary fiber removal in step (1) are combined and further dried or baked to obtain combustible components, which are then briquetteed into waste-derived fuel products.

[0014] (6) Through the above steps, the separation of organic components, heavy inert components and combustible components in anaerobic fermentation biogas residue was completed, and full resource utilization was achieved.

[0015] Furthermore, when the anaerobic fermentation biogas residue is obtained through anaerobic fermentation of kitchen waste or strictly classified kitchen waste, a cyclone desanding device is used for primary desanding and separation.

[0016] When anaerobic fermentation biogas residue is obtained from the anaerobic fermentation of domestic waste or kitchen waste that is not strictly classified, it is separated by gravity settling.

[0017] Furthermore, the secondary fiber debris removal process is carried out in a drum screen.

[0018] The drum screen is configured to be tilted at 5-10°, the screen mesh size is 30-60 mesh, and the drum rotation speed is 20-50 rpm.

[0019] Furthermore, the drum screen cleaner adopts a self-cleaning method based on the rolling of the drum. Compared with the hydraulic screen, which also uses gravity separation, the drum screen uses rotation to form fibrous debris into clumps, thereby achieving self-cleaning of the screen. In some practical cases, the hydraulic screen becomes clogged after only 10 minutes of operation. The drum screen structure can significantly extend the cleaning cycle to more than 30 days.

[0020] Furthermore, the drum impurity remover uses a 30-60 mesh screen, which is more effective at removing impurities, mainly consisting of flexible materials such as short fibers and broken plastics. The removal rate of short fibers and broken plastics can reach over 90%. In contrast, screening equipment that uses external forces such as extrusion and centrifugation often only achieves a removal rate of 40-50% due to the flexible nature of short fibers and broken plastics, which seriously affects the resource utilization properties of nutrient soil products.

[0021] Furthermore, during the primary sand removal and secondary fiber debris removal processes, gravel impurities and fiber debris impurities are generated respectively. The gravel impurities are washed and drained to obtain pure gravel with a moisture content of <5%. The fiber debris impurities are dehydrated and dried to be used as waste-derived fuel.

[0022] Furthermore, the conditioning tank is designed to have a residence time of 12-24 hours, with two tanks installed and operating alternately. The conditioning time in the conditioning tank is 2-4 hours. After the aforementioned process, the solid content of the feed to the conditioning tank is designed to be 2-5%.

[0023] Furthermore, the maturation and aging time is 25-35 days, and the pile temperature is controlled at 65-75℃.

[0024] Furthermore, before composting and aging, sawdust (15-25% by weight of the dewatered sludge cake) is added as an additive, and no further flocculants such as PAC or PAM are added. This process alters the sludge's properties, aiding in better flocculation and separation; additionally, the final nutrient soil product is more fluffy, making it ideal for landscaping and floriculture. The dewatered sludge cake has a solids content of 55-65%.

[0025] Furthermore, before anaerobic fermentation of kitchen waste and / or household waste to obtain anaerobic fermentation biogas residue, it undergoes pretreatment to separate magnetic metals from scum and impurities.

[0026] Furthermore, the biogas produced during anaerobic fermentation is used to generate electricity, while the biogas slurry is sent to the sewage treatment system for treatment before being discharged in compliance with standards.

[0027] The water used for diluting biogas residue in this invention does not require clean water. It is produced by a plate and frame filter press and / or a wastewater treatment system. After primary sand removal / secondary fiber removal / conditioning / plate and frame filtration, the aqueous phase is collected in the plate and frame filter press water tank. The process water is recycled, and part of the produced water is discharged to the wastewater treatment system. The overall water replacement cycle of the wet integrated sorting system is >30 days.

[0028] This invention employs a sequential process to remove impurities larger than 10mm, heavy inert components, short fiber impurities, and nutrient soil from anaerobic fermentation biogas residue. This process orderly separates the anaerobic fermentation biogas residue into organic components (nutrient soil), inert components (gravel), and combustible components (impurities such as shredded textiles and short fibers). Each component after separation meets the relevant product quality specifications, thus achieving the goal of full resource utilization of anaerobic fermentation biogas residue.

[0029] The method of this invention removes gravel and fiber impurities from anaerobic fermentation biogas residue, resulting in a highly homogeneous organic slurry. After dehydration and aerobic maturation and aging, these organic components yield nutrient soil with uniform particle size and low impurity content. The biogas residue resource products processed in this way include gravel that can be used as roadbed material or further separated to extract broken glass for deeper utilization; nutrient soil that can be used as a substrate for landscaping and flower cultivation; and short fibers that have been screened out that can be further dehydrated and dried to produce fuel rods for resource utilization. The dehydrated aqueous phase is partially recycled for biogas residue dilution, and a portion is treated by a wastewater treatment unit before being discharged.

[0030] Compared with existing technologies, this invention, through wet comprehensive sorting of anaerobic fermentation residue, can fully utilize the vast majority of solid components in the residue, solving the current bottleneck problem of the difficulty in utilizing anaerobic fermentation residue for resource purposes, and significantly improving the resource utilization rate and volume reduction rate of municipal solid waste / kitchen waste treatment technology based on anaerobic fermentation as the main process. Attached Figure Description

[0031] Figure 1 This is a flow chart of the wet impurity removal process for anaerobic fermentation biogas residue from municipal solid waste in Example 1;

[0032] Figure 2 This is a flow chart of the wet impurity removal process for anaerobic fermentation biogas residue of kitchen waste in Example 2;

[0033] Figure 3 This is a material state diagram of the biogas residue after fermentation;

[0034] Figure 4 A state diagram of the nutrient soil product;

[0035] Figure 5 This is a graph showing the physical properties of the dewatered cement cake. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0037] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0038] To achieve full resource utilization of biogas residue and overcome bottlenecks in the resource utilization of anaerobic fermentation biogas residue, this invention provides a method for wet comprehensive sorting of anaerobic fermentation biogas residue, comprising the following steps:

[0039] (1) The anaerobic fermentation biogas residue of kitchen waste and / or domestic waste is diluted and centrifuged in sequence to remove impurities with a particle size >10mm. The resulting liquid phase is then subjected to a first sand removal separation and a second fiber debris removal treatment to obtain a liquid phase containing organic components.

[0040] (2) The liquid phase containing organic components and the sludge generated by the sewage treatment system are fed into the conditioning tank together, and a conditioning agent is added. Then, the mixture is dewatered by pressure filtration to obtain dewatered cake.

[0041] (3) After the dewatered soil cake is crushed, it is sent to the composting and aging tank for composting and aging to obtain the nutrient soil product.

[0042] (4) The heavy inert component obtained after the first sand removal and separation in step (1) is further washed with water to obtain the gravel product;

[0043] (5) The impurity components obtained after centrifugation in step (1) and the fiber debris components obtained after secondary fiber removal in step (1) are combined and further dried or baked to obtain combustible components, which are then briquetteed into waste-derived fuel products.

[0044] (6) Through the above steps, the separation of organic components, heavy inert components and combustible components in anaerobic fermentation biogas residue was completed, and full resource utilization was achieved.

[0045] In some specific implementations, when anaerobic fermentation biogas residue is obtained from the anaerobic fermentation of kitchen waste or strictly classified kitchen waste, its glass and ceramic content is relatively low, while the material viscosity is relatively high. Therefore, a cyclone desanding device can be used for primary desanding and separation.

[0046] In some specific implementations, when anaerobic fermentation biogas residue is obtained from the anaerobic fermentation of domestic waste or kitchen waste that is not strictly classified, the biogas residue has a low viscosity, but the mud and sand content can reach 8-10%, and a gravity sedimentation method can be used for primary sand removal and separation.

[0047] In some specific implementations, before the anaerobic fermentation biogas residue undergoes a sand removal and separation process, dilution water is added to adjust the viscosity or solids content. Optionally, the volume ratio of dilution water to biogas residue can be 2 to 3:1.

[0048] There are various types of equipment for solid-liquid separation, such as hydraulic screens, screw presses, spiral extruders, horizontal screw centrifugal dewatering machines, and plate and frame filter presses. All of these devices can separate the aqueous and solid phases. However, for separating organic components and short fibers, due to the inherent softness and deformability of fibers and plastic fragments, they easily pass through the screen and enter the aqueous phase under centrifugal and compressive forces. Excessive fiber debris entering the aqueous phase severely affects the quality of the final product. While hydraulic screens can theoretically remove fiber fragments, in actual operation, textile fibers easily entangle and accumulate in the screen gaps, and the surface friction resistance of metal screens is relatively high, leading to screen clogging within minutes and affecting actual processing capacity. Therefore, in some specific embodiments of this invention, the secondary fiber debris removal process is carried out in a drum screen, utilizing the drum screen to separate organic components from fiber fragments.

[0049] The drum screen is configured to be tilted at 5-10°, with a screen mesh size of 30-60 mesh and a drum rotation speed of 20-50 rpm. The intercepted fiber debris and broken plastic pieces form clumps inside the drum and are discharged from the end outlet due to the combined effect of the drum rotation and the tilt angle. In addition, preferably, the screen can be made of polymer material to provide a smoother surface, which is more conducive to the removal of impurities.

[0050] In some specific embodiments, the primary sand separation and secondary fiber debris removal processes also generate gravel impurities and fiber debris impurities. The separated gravel impurities are then washed with water to remove residual organic matter and fiber impurities adhering to the surface. After natural drainage, pure gravel with a moisture content of <5% is obtained, which can be used as a road subbase. Fiber debris impurities (such as various fibers, broken plastic pieces, and other debris) are intercepted in the oversize component and, after further dehydration and drying, can be sold as waste-derived fuel (RDF) as an alternative fuel.

[0051] In some specific implementations, the conditioning tanks are designed with a residence time of 12-24 hours, with two tanks operating alternately. The conditioning time within the tanks is 2-4 hours. After the aforementioned process, the solids content of the feed to the conditioning tanks is designed to be 2-5%. Furthermore, 15%-25% of the sawdust in the conditioning tanks is used as a conditioning agent, and no flocculants such as PAC or PAM are added. This approach alters the sludge properties, aiding in better flocculation and separation. Additionally, the final nutrient soil product is more fluffy, making it highly suitable for landscaping and floriculture applications.

[0052] In some specific implementations, the maturation and aging time is 25-35 days, and the pile temperature is 65-75℃.

[0053] In some specific embodiments, sawdust, comprising 15-25% of the oven-dried mud mass, is added as an additive before pressure filtration and dewatering. Additionally, the solids content of the dewatered mud cake can be 55-65%.

[0054] In some specific implementations, before anaerobic fermentation of kitchen waste and / or household waste to obtain anaerobic fermentation biogas residue, pretreatment is performed to separate magnetic metals from floating scum impurities.

[0055] In a more specific implementation, the biogas produced during anaerobic fermentation is used to generate electricity, while the biogas slurry is sent to a wastewater treatment system for treatment before being discharged in compliance with standards or recycled as dilution water.

[0056] In some specific embodiments, the water generated during the filter press dewatering process of the present invention can be recycled as dilution water. After circulating for 3 to 5 days, it is then discharged into the wastewater treatment system for treatment to avoid the accumulation of ammonia nitrogen and salt. The water treated by the wastewater treatment system can be partially reused in the biogas residue wet sorting system without the need to introduce additional clean water.

[0057] Each of the above implementation methods can be implemented individually, or in any combination of two or more.

[0058] The above implementation methods will be described in more detail below with reference to specific embodiments.

[0059] Example 1:

[0060] like Figure 1 As shown, the designed moisture content of municipal solid waste is 45-55%, textile content is 10-20%, plastic content is 10-15%, organic matter content is 5-15%, and glass, ceramics, and ash content is 10-20%. After pretreatment to remove magnetic metals, textiles, plastics, and other impurities, the material enters the dry anaerobic fermentation unit. The moisture content of the fermented biogas residue is approximately 35-40% (material state as shown). Figure 3 (As shown).

[0061] Because municipal solid waste contains a lot of textiles, plastics, and ash, but has good liquid phase fluidity and low viscosity, the ratio of circulating dilution water to biogas residue is 2-3:1 (in this example, a volume ratio of 2.5:1 is selected), that is, the moisture content of biogas residue is adjusted to about 10%. Then, it is separated by a biomass separator with a screen aperture of 8-10mm. Most of the larger particles of textiles and plastics are screened out, while the broken glass ceramics, ash, and organic components are washed into the liquid phase by the circulating dilution water and enter the spiral desanding device through the screen.

[0062] The spiral desanding device is designed with a residence time of approximately 15 minutes, allowing sufficient time for glass, ceramics, and ash to settle to the bottom of the hopper before being removed by the spiral. The liquid phase after removing heavy materials contains approximately 25% organic matter and 75% fibrous impurities. This liquid phase is pumped into a drum screen (i.e., a drum impurity remover) for further impurity removal. The drum screen is set at a 5° inclination angle, uses a 30-mesh nylon screen, and has an adjustable drum rotation speed of 20–50 rpm. Fiber impurities are trapped inside the drum and eventually roll to the end outlet under gravity. They are then conveyed by a screw conveyor and mixed with textile impurities removed by the preceding biomass separator. After being pressed and dewatered by a screw extruder, the screw extruder presses at a pressure of 0.8 MPa with an 8 mm screen. The extruded solid phase is further thermally dried to produce fuel rods, which can provide a calorific value of 3000–5000 kcal / kg. The liquid phase obtained from the screw extruder is then used as circulating dilution water.

[0063] After sand and impurity removal from the liquid phase in the drum screen, the solids consist only of organic components. These liquid components enter a conditioning tank for conditioning. The overall design residence time of the conditioning tank is 24 hours, with two tanks installed and operating alternately. The conditioning time in the conditioning tank is 2-4 hours. After the aforementioned process, the design feed solids content of the conditioning tank is 5%. 20% sawdust by weight of the oven-dried mud is added as an additive, followed by filtration through a plate and frame filter press. The resulting mud cake has a solids content of approximately 50-55%. The mud cake is then crushed and sent to a composting and aging unit for composting. After 28 days of composting and aging, the nutrient soil product (such as...) is obtained. Figure 4After inspection and packaging, the nutrient soil is sold. In this example, the yield of nutrient soil compared to household waste raw materials is about 4%, the moisture content is <40%, and the organic matter content is 25-35%.

[0064] The aqueous phase produced by the plate and frame filter press is partially recycled (approximately 70%) as circulating dilution water, and a portion (approximately 30%) is sent to the wastewater treatment system for treatment before being discharged.

[0065] The glass, ceramics, and ash components removed by the spiral sand separator can be further cleaned to remove residual organic components and fibers adhering to the surface, and then used as a road subbase for resource utilization. In this example, the sand and gravel account for about 7-10% of the raw material of municipal solid waste, and the moisture content is <5%.

[0066] In this example, the dry basis of the fuel rods accounts for approximately 20% of the municipal solid waste raw material, with a moisture content of <20%, and can provide a calorific value of 3000-5000 kcal / kg, serving as an alternative fuel for resource utilization.

[0067] Through the above processing, the full-component resource utilization of anaerobic fermentation biogas residue from municipal solid waste was achieved. After wet comprehensive sorting, the anaerobic fermentation biogas residue from municipal solid waste yielded three resource products: nutrient soil, gravel, and fuel rods, without generating any other solid waste or wastewater.

[0068] Anaerobic fermentation biogas residue, produced from municipal solid waste, undergoes a process involving blending and dilution, impurity removal via biomass separator, gravity sand removal, removal of fibrous impurities via drum screen, addition of sawdust (25% of the dry weight of the biogas) as a conditioner, and pressing and dehydration. The resulting biogas cake, tested by a third-party organization, shows an organic matter content of 44.3%, far exceeding the 25% requirement of GB / T23486-2009. Furthermore, heavy metal elements such as cadmium, mercury, and lead are more than two orders of magnitude lower than the upper limit of this standard (e.g., ...). Figure 5 It has been widely used in landscaping and flower cultivation in the region.

[0069] Example 2:

[0070] For well-sorted kitchen waste (meaning impurity content is less than 5%), the designed raw material moisture content is 70-75%, and the impurity content of plastics, bamboo, wood, glass, etc. is about 5-15%. In the pretreatment stage, 80-85% of impurities can be removed. After impurity removal and pulping, the kitchen waste undergoes anaerobic fermentation, degrading 60-70% of organic matter. The resulting biogas residue has a solids content of about 15-20% and an impurity content of about 5%.

[0071] Because the sludge from kitchen waste has a high viscosity, the dilution ratio of water to sludge is controlled at 2-3:1 (2.5:1 is selected in this example) to dilute the material to a solid content of about 4%. The diluted sludge is then removed by a cyclone desanding device to remove sand impurities. The sand impurity components have a moisture content of about 60% and an organic matter content of <20%, and are then transported off-site for landfill disposal.

[0072] Even after sand removal, some fragmented plastic remains in the biogas sludge. This liquid phase is pumped into a rotary drum screen for impurity removal. The drum screen is set at a 5° inclination angle, uses a 30-mesh nylon screen, and has an adjustable rotation speed of 20-50 rpm. Fiber impurities are trapped inside the drum and eventually roll to the discharge port under gravity. The solid sludge is further compressed and dehydrated to below 60% moisture content by a screw press before being mixed with sand and other impurities and transported to landfills. The total amount transported to landfills accounts for approximately 1-2% of the total incoming kitchen waste.

[0073] After sand removal, the organic slurry is filtered through a plate and frame filter press. The solids content of the sludge cake is approximately 35-40%. The sludge cake is further crushed and then sent to a composting and aging unit for approximately 28 days, ultimately yielding nutrient soil / organic fertilizer. The nutrient soil / organic fertilizer has a moisture content of <40% and an organic matter content of >30%. By adding nutrients such as nitrogen and phosphorus, various types of organic fertilizers can be produced. The nutrient soil / organic fertilizer accounts for approximately 8-12% of the raw material yield from kitchen waste.

[0074] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for wet comprehensive separation of anaerobic fermentation biogas residue, characterized in that, Includes the following steps: Step (1): The anaerobic fermentation biogas residue of domestic waste is diluted and centrifuged in sequence to remove impurities with a particle size >10mm. The resulting liquid phase is then subjected to a first sand removal separation and a second fiber debris removal treatment to obtain a liquid phase containing organic components. Step (2): The liquid phase containing organic components and the sludge generated by the sewage treatment system are sent into the conditioning tank together, and a conditioning agent is added. Then, the mixture is dewatered by pressure filtration to obtain dewatered cement cake. Step (3): After crushing the dewatered cement cake, send it into the composting and aging tank for composting and aging to obtain the nutrient soil product; Step (4): The heavy inert component obtained after the first sand removal and separation in step (1) is further washed with water to obtain the gravel product; Step (5): The impurity components obtained after centrifugation in step (1) and the fiber debris components obtained after secondary fiber removal in step (1) are combined and further dried or baked to obtain combustible components, which are then briquetteed into waste-derived fuel products. Step (6): Through the above steps, the separation of organic components, heavy inert components, and combustible components in anaerobic fermentation biogas residue was completed, realizing full resource utilization; In step (2), add 15%-25% sawdust as a conditioner; In step (2), the design residence time of the conditioning tank is 12-24 hours, and two tanks are set up to operate alternately. The conditioning time in the conditioning tank is 2-4 hours, and the solid content of the feed to the conditioning tank is designed to be 2-5%. The wastewater treatment system in step (2) is used to treat the biogas slurry produced by the anaerobic fermentation of domestic waste.

2. The method for wet comprehensive separation of anaerobic fermentation biogas residue according to claim 1, characterized in that, The secondary fiber debris removal process is carried out in a drum screen. The drum screen is configured to be tilted at 5-10°, the screen mesh size is 30-60 mesh, and the drum rotation speed is 20-50 rpm.

3. The method for wet comprehensive sorting of anaerobic fermentation biogas residue according to claim 1, characterized in that, During the primary sand removal and secondary fiber debris removal processes, gravel impurities and fiber debris components are generated respectively. The gravel impurities, i.e. the heavy inert components, are washed and drained to obtain pure gravel with a moisture content of <5%. The fiber debris components are dehydrated and dried to serve as the waste-derived fuel product.

4. The method for wet comprehensive sorting of anaerobic fermentation biogas residue according to claim 1, characterized in that, The composting and aging process takes 25-35 days, and the temperature of the compost pile is controlled at 65-70℃.

5. The method for wet comprehensive sorting of anaerobic fermentation biogas residue according to claim 1, characterized in that, The water used for diluting biogas residue is produced by a plate and frame filter press and / or a wastewater treatment system. The water phase generated by the primary sand removal and secondary fiber debris removal in step (1), and the conditioning and pressure filtration in step (2) is collected in the product water tank of the plate and frame filter press. Part of it is recycled as process water, and the other part is discharged to the sewage treatment system to control the overall water replacement cycle in the wet integrated sorting process to be >30 days.

6. The method for wet comprehensive separation of anaerobic fermentation biogas residue according to claim 1, characterized in that, Before anaerobic fermentation to obtain anaerobic digestate, municipal solid waste undergoes pretreatment to separate magnetic metals from floating scum and impurities.

7. The method for wet comprehensive separation of anaerobic fermentation biogas residue according to claim 6, characterized in that, The biogas produced during anaerobic fermentation is used to generate electricity, while the biogas slurry is sent to the sewage treatment system for treatment before being discharged in compliance with standards.

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