Kitchen waste anaerobic digestion treatment and resource utilization system

Abstract

The invention discloses a kitchen waste anaerobic digestion treatment and resource utilization system which comprises a pretreatment subsystem, an anaerobic digestion subsystem, a biogas purification and utilization subsystem and a biogas slurry and biogas residue resource subsystem which are sequentially connected along the material flow direction, the pretreatment subsystem is used for carrying out impurity separation, pulping and oil extraction on incoming kitchen waste; and the anaerobic digestion subsystem is used for carrying out hydrolytic acidification and methanogenesis reaction on the pretreated organic slurry to generate biogas. According to the invention, through integration of high-efficiency pyrohydrolysis pretreatment, two-phase anaerobic digestion enhancement and multi-element resource deep treatment, the spanning of kitchen waste treatment from reduction to high value is realized, and the beneficial technical effects of the system are reflected in that: through pyrohydrolysis and multi-stage separation pretreatment, the organic matter degradation efficiency and the grease recovery rate are remarkably improved; and the acidification risk of the system is effectively relieved by combining two-phase anaerobic digestion with a trace element strengthening strategy, and the biogas yield and the operation stability are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment and resource utilization technology, specifically relating to an anaerobic digestion treatment and resource utilization system for kitchen waste. Background Technology

[0002] Food waste is a major component of urban household waste in my country, characterized by high organic content, high water content, easy decomposition and foul odor, and high oil content. Improper handling can not only cause serious environmental pollution but also lead to resource waste.

[0003] Currently, the main methods for treating food waste include landfill, incineration, and aerobic composting. These methods have many drawbacks: landfill occupies a large amount of land and produces leachate and greenhouse gases; incineration requires the addition of auxiliary fuel due to the low calorific value of food waste and is prone to producing dioxins; aerobic composting products have low fertilizer efficiency and may pose a risk of heavy metal pollution.

[0004] Anaerobic digestion technology can convert the organic matter in food waste into clean energy—biogas—while simultaneously producing nutrient-rich digestate and slurry, making it an ideal way to achieve the "reduction, resource recovery, and harmlessness" of food waste. However, existing anaerobic digestion systems for food waste generally suffer from the following problems:

[0005] 1. Incomplete pretreatment: The separation efficiency of impurities (such as plastics, glass, metals, etc.) is low, which affects the operation and digestion stability of subsequent equipment; the oil recovery rate is low, and high-value utilization is not achieved.

[0006] 2. Unstable system operation: The protein and lipids in food waste are prone to producing ammonia nitrogen and long-chain fatty acid accumulation during digestion, which inhibits methanogenic bacteria and leads to system acidification and failure.

[0007] 3. Limited resource products and low added value: Usually only the biogas power generation grid connection is considered, and the deep utilization of biogas slurry and biogas residue is insufficient, resulting in limited economic benefits.

[0008] 4. Low level of intelligence: The system relies heavily on manual experience for control, making it difficult to cope with the impact of fluctuations in the composition of food waste, resulting in low operating efficiency.

[0009] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a system for the anaerobic digestion and resource utilization of kitchen waste.

[0010] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0011] The purpose of this invention is to provide a system for the anaerobic digestion and resource utilization of kitchen waste, which integrates efficient pretreatment, two-phase anaerobic digestion, and deep resource utilization of the products.

[0012] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0013] A system for anaerobic digestion and resource utilization of kitchen waste includes a pretreatment subsystem, an anaerobic digestion subsystem, a biogas purification and utilization subsystem, and a biogas slurry and biogas residue resource utilization subsystem connected sequentially along the material flow direction. The pretreatment subsystem is used to separate impurities, slurry, and extract oil from the incoming kitchen waste. The anaerobic digestion subsystem is used to hydrolyze, acidify, and perform methanogenesis reactions on the pretreated organic slurry to produce biogas. The biogas purification and utilization subsystem is used to desulfurize, store, and utilize the generated biogas for energy. The biogas slurry and biogas residue resource utilization subsystem is used to perform solid-liquid separation on the effluent after anaerobic digestion and to perform deep treatment and resource utilization on the separated biogas slurry and biogas residue, respectively.

[0014] In one or more embodiments of the present invention, the pretreatment subsystem includes a receiving bin, a crusher, a hot hydrolysis reactor, a hydrocyclone, a fine pulping machine, and a horizontal centrifuge connected in sequence; the hot hydrolysis reactor operates at a pressure of 0.5-1.2 MPa, a temperature of 120-160°C, and a reaction time of 15-40 minutes; the hydrocyclone is used to separate heavy impurities; the fine pulping machine has a built-in fine screen for separating light impurities and pulping the material; the horizontal centrifuge is used to extract crude oil from the slurry. Through high-temperature and high-pressure hydrothermal treatment, the complex organic structure and pathogenic microorganisms in the kitchen waste are thoroughly destroyed. This not only significantly improves the biodegradability of subsequent anaerobic digestion, shortens digestion time, and increases biogas production, but also sterilizes the material and promotes the release of intracellular oils, thereby synergistically improving the overall system's processing efficiency, operational stability, and oil recovery rate.

[0015] In one or more embodiments of the present invention, the pretreatment subsystem further includes a sedimentation tank and a debris removal device disposed between the hydrocyclone and the fine pulping machine for further removal of fine sand and fibrous impurities. Its technical function is to perform deep purification, aiming to further remove fine gravel, suspended solids, and entangled fibers remaining after hydrocyclone treatment. This design effectively prevents these minute impurities from accumulating in subsequent pipelines and equipment, avoiding wear and blockage of precision components such as pumps, valves, and membrane systems, and ensuring long-term stable operation of the system.

[0016] In one or more embodiments of the present invention, the anaerobic digestion subsystem includes a slurry buffer tank, a hydrolysis acidification tank, and a methanogenic tank connected in series. The hydrolysis acidification tank is equipped with a mechanical stirrer and a heating coil to control the reaction temperature at 35-40°C. The methanogenic tank is a completely mixed anaerobic reactor with a three-stage circulating water distributor and a double-membrane gas storage tank integrated at the top. The methanogenic tank is also equipped with an external circulation network and an automatic micronutrient dosing device connected to the external circulation network. The micronutrients include at least iron, cobalt, and nickel. The external circulation can enhance the hydraulic stirring and mass transfer efficiency within the reactor, ensuring sufficient contact between the substrate and microorganisms, and diluting any inhibitory substances that may be present in the influent. The automatic dosing of key micronutrients such as iron, cobalt, and nickel can directly meet the metabolic needs of anaerobic microorganisms such as methanogens, effectively alleviating metabolic inhibition caused by nutrient deficiency, and is a key guarantee for maintaining stable system operation under high load conditions.

[0017] In one or more embodiments of the present invention, the operating temperature of the methanogenic tank is controlled at a mesophilic range of 35-38°C or a thermophilic range of 50-55°C. This provides an optimal and constant growth environment for anaerobic microorganisms (mainly methanogenic archaea). The option of both mesophilic and thermophilic microbial communities gives the system a degree of operational flexibility, allowing it to select the optimal strategy based on regional climate, energy costs, and processing requirements, thereby maximizing methane yield and reaction rate.

[0018] In one or more embodiments of the present invention, the biogas purification and utilization subsystem includes a biological desulfurization tower, a gas holder, and a biogas utilization unit connected in sequence; the biogas utilization unit is a combined heat and power unit or a biogas purification and biomethane device. Its technical function lies in utilizing the biological metabolism of specific sulfur-oxidizing bacteria to convert hydrogen sulfide in biogas into elemental sulfur or sulfate. Compared with traditional chemical desulfurization, this method has significant advantages such as lower operating costs, no need to add chemical agents, no secondary pollution, and high desulfurization efficiency, making it a greener and more economical purification method.

[0019] In one or more embodiments of the present invention, the biogas slurry and biogas residue resource utilization subsystem includes a solid-liquid separator, a biogas slurry temporary storage tank connected to the liquid phase outlet of the solid-liquid separator, and a biogas residue buffer tank connected to the solid phase outlet of the solid-liquid separator. The outlet of the biogas slurry temporary storage tank is divided into two paths: one path is connected to the hydrolysis acidification tank via a return pipe, and the other path is connected to the biogas slurry deep treatment unit. The biogas slurry deep treatment unit is a nanofiltration and reverse osmosis membrane system. The concentrate outlet of the nanofiltration membrane is used to produce liquid organic fertilizer, and the permeate outlet of the reverse osmosis membrane produces recycled water. The outlet of the biogas residue buffer tank is divided into two paths: one path is connected to the aerobic fermentation chamber to produce solid organic fertilizer, and the other path is connected to the carbonization reactor to produce biochar. Its function is to convert biogas residue into biochar through pyrolysis technology. This transformation greatly increases the added value of the product. Biochar can be used as a high-quality soil conditioner or environmentally friendly adsorbent, realizing a leap from waste treatment to high-value material production and broadening the system's profit channels.

[0020] In one or more embodiments of the present invention, a biogas slurry fermentation and acid production unit is further provided before the biogas slurry deep treatment unit to enrich volatile fatty acids as raw materials for synthesizing biodegradable plastics. Its core function is to directionally convert the residual organic carbon source in the biogas slurry into high-purity volatile fatty acids by regulating the fermentation process. This upgrades low-value biogas slurry into a high-value raw material for synthesizing biodegradable plastics, opening up a completely new and highly efficient resource utilization pathway, and is a key innovation point for realizing "turning waste into treasure" and improving the economics of the project.

[0021] In one or more embodiments of the present invention, the system further includes an intelligent control subsystem; the intelligent control subsystem includes sensors, a central controller, and actuators deployed at key nodes of the system; the sensors are used to monitor pH, redox potential, temperature, liquid level, biogas flow rate, and component parameters in real time; the central controller outputs optimized control commands based on sensor data and combined with a digital twin model and big data analysis algorithms; the actuators are used to receive control commands and adjust the operating status of the feed pump, return pump, heating system, stirring device, and trace element dosing device. Its function is to achieve a leap from "passive response" to "active prediction and optimization." By creating a virtual model of the system and combining historical and real-time data, system performance can be simulated and predicted, potential faults can be diagnosed, and optimal control strategies can be generated autonomously, thereby significantly improving the system's automation, intelligence, and overall operational efficiency.

[0022] A method for anaerobic digestion and resource utilization of kitchen waste includes the following steps:

[0023] S1. The kitchen waste undergoes multi-stage pretreatment, including hot water hydrolysis, to separate heavy impurities, light impurities, and crude oil, resulting in a higher-quality and more easily digestible organic slurry.

[0024] S2. The organic slurry is subjected to hydrolysis acidification and methanogenesis reaction in sequence, and the methanogenesis process is enhanced by adding trace elements to produce biogas.

[0025] S3. Conduct biological desulfurization, storage, and energy utilization of the generated biogas;

[0026] S4. The effluent after anaerobic digestion is subjected to solid-liquid separation to obtain biogas slurry and biogas residue;

[0027] S5. Part of the biogas slurry is recycled to the hydrolysis and acidification step, and the remaining biogas slurry is fermented to produce acid and enrich VFAs. Then, it is subjected to membrane deep treatment to obtain PHA synthesis raw materials, liquid organic fertilizer and recycled water, respectively.

[0028] S6. Mix a portion of the biogas residue with a conditioner and carry out aerobic fermentation to produce solid organic fertilizer or cultivation substrate, and carbonize the other portion to produce biochar.

[0029] Compared with existing technologies, this invention achieves a leap from "reduction" to "high-value" in food waste treatment by integrating efficient hot water hydrolysis pretreatment, enhanced two-phase anaerobic digestion, and multi-resource deep treatment. Its beneficial technical effects are concentrated in the following aspects: the system significantly improves organic matter degradation efficiency and oil recovery rate through hot water hydrolysis and multi-stage sorting pretreatment; and effectively mitigates the risk of system acidification through a two-phase anaerobic digestion combined with a trace element enhancement strategy, greatly improving biogas production and operational stability. Simultaneously, the system innovatively converts biogas slurry into liquid fertilizer, recycled water, and bioplastic raw materials, and biogas residue into organic fertilizer and biochar, forming a diversified product output system of "energy-fertilizer-materials-water," greatly enhancing resource recovery value and economic benefits. Furthermore, the application of full-process intelligent control and digital twin technology ensures adaptive and optimized operation of the system under various working conditions, ultimately maximizing the unity of energy recovery, environmental benefits, and economic benefits in food waste treatment. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of an anaerobic digestion and resource utilization system for kitchen waste according to an embodiment of the present invention;

[0032] Figure 2 This is a system diagram of the preprocessing subsystem in this invention;

[0033] Figure 3 This is a flowchart of the processing scheme of the present invention.

[0034] Explanation of key figure labels:

[0035] 1-Receiving bin, 2-Crusher, 3-Hot water hydrolysis reactor, 4-Hydrocyclone, 5-Pulping machine, 6-Horizontal centrifuge, 7-Sedimentation tank, 8-Impurity removal device. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0037] like Figure 1 As shown, an embodiment of the present invention discloses an anaerobic digestion and resource utilization system for kitchen waste, comprising a pretreatment subsystem, an anaerobic digestion subsystem, a biogas purification and utilization subsystem, and a biogas slurry and biogas residue resource utilization subsystem connected sequentially along the material flow direction. The pretreatment subsystem is used to separate impurities, slurry, and extract oil from the incoming kitchen waste; the anaerobic digestion subsystem is used to hydrolyze, acidify, and perform methanogenic reactions on the pretreated organic slurry to produce biogas; the biogas purification and utilization subsystem is used to desulfurize, store, and utilize the generated biogas for energy; and the biogas slurry and biogas residue resource utilization subsystem is used to perform solid-liquid separation on the effluent after anaerobic digestion, and to perform deep treatment and resource utilization on the separated biogas slurry and biogas residue respectively.

[0038] The working principle of this anaerobic digestion and resource utilization system for kitchen waste is as follows: Through the precise coupling and synergy of a series of physical, chemical, and biological processes, the system achieves the step-by-step separation and targeted transformation of different components in kitchen waste, ultimately achieving comprehensive energy and resource recovery. Specifically: First, the pretreatment subsystem uses physical methods such as multi-stage sorting, crushing, pulping, and centrifugal oil extraction to separate the mixed kitchen waste into waste impurities, recovered crude oil, and homogenized organic slurry, creating pure and efficient substrate conditions for subsequent biological treatment. Next, the organic slurry enters the core of the anaerobic digestion subsystem—the hydrolysis-acidification and methanogenic two-phase reactor. Here, through the relay action of microbial communities such as hydrolytic bacteria, acidifying bacteria, and methanogenic bacteria, the organic matter in the slurry is gradually degraded and ultimately converted into biogas with methane as the main component, completing the transformation from waste to biogas. The process involves converting waste organic matter into clean energy. Subsequently, the biogas produced is desulfurized and stored through a purification and utilization subsystem, and is ultimately used for power generation or purified into biogas, achieving energy utilization. Finally, the digested residues (biogas slurry and biogas residue) enter the resource utilization subsystem, where they are further transformed into diversified resource products such as liquid organic fertilizer, recycled water, and solid organic fertilizer through solid-liquid separation and subsequent advanced treatment (such as membrane concentration and aerobic fermentation). This constructs a complete, closed-loop, and efficient recycling system from "waste" to "energy" and "resources".

[0039] like Figure 2 As shown, the pretreatment subsystem includes a receiving chamber 1, a crusher 2, a hot hydrolysis reactor 3, a hydrocyclone 4, a fine pulping machine 5, and a horizontal centrifuge 6 connected in sequence. The hot hydrolysis reactor 3 operates at a pressure of 0.5-1.2 MPa, a temperature of 120-160℃, and a reaction time of 15-40 minutes. The hydrocyclone 4 is used to separate heavy impurities. The fine pulping machine 5 has a built-in fine screen for separating light impurities and pulping the material. The horizontal centrifuge 6 is used to extract crude oil from the slurry.

[0040] like Figure 2 As shown, the pretreatment subsystem also includes a sedimentation tank 7 and a debris removal device 8 located between the hydrocyclone 4 and the fine pulping machine 5, for further removal of fine sand and fibrous debris.

[0041] Specifically, the anaerobic digestion subsystem includes a slurry buffer tank, a hydrolysis acidification tank, and a methanogenic tank connected in series. The hydrolysis acidification tank is equipped with a mechanical stirrer and heating coils to control the reaction temperature at 35-40℃. The methanogenic tank is a completely mixed anaerobic reactor with a three-stage circulating water distributor and a double-membrane gas storage tank integrated on top. The methanogenic tank is also equipped with an external circulation pipeline and an automatic trace element dosing device connected to the external circulation pipeline. The trace elements include at least iron, cobalt, and nickel.

[0042] Specifically, the operating temperature of the methane production tank is controlled at a medium temperature of 35-38℃ or a high temperature of 50-55℃.

[0043] Specifically, the biogas purification and utilization subsystem includes a biological desulfurization tower, a gas holder, and a biogas utilization unit connected in sequence; the biogas utilization unit is a combined heat and power unit or a biogas purification and biomethane device.

[0044] Specifically, the biogas slurry and biogas residue resource utilization subsystem includes a solid-liquid separator, a biogas slurry storage tank connected to the liquid phase outlet of the solid-liquid separator, and a biogas residue buffer tank connected to the solid phase outlet of the solid-liquid separator. The outlet of the biogas slurry storage tank is divided into two paths: one path is connected to the hydrolysis acidification tank through a return pipeline, and the other path is connected to the biogas slurry deep treatment unit. The biogas slurry deep treatment unit is a nanofiltration and reverse osmosis membrane system. The concentrate outlet of the nanofiltration membrane is used to produce liquid organic fertilizer, and the permeate outlet of the reverse osmosis membrane produces recycled water. The outlet of the biogas residue buffer tank is divided into two paths: one path is connected to the aerobic fermentation chamber to produce solid organic fertilizer, and the other path is connected to the carbonization reactor to produce biochar.

[0045] Specifically, a biogas slurry fermentation and acid production unit is set up before the biogas slurry deep treatment unit to enrich volatile fatty acids as raw materials for the synthesis of biodegradable plastics.

[0046] Specifically, the system also includes an intelligent control subsystem; the intelligent control subsystem includes sensors, a central controller, and actuators deployed at key nodes of the system; the sensors are used to monitor pH, redox potential, temperature, liquid level, biogas flow rate, and component parameters in real time; the central controller outputs optimized control commands based on sensor data and combined with digital twin models and big data analysis algorithms; the actuators are used to receive control commands and adjust the operating status of the feed pump, return pump, heating system, stirring device, and trace element dosing device.

[0047] like Figure 3 As shown, another embodiment of the present invention provides a method for anaerobic digestion treatment and resource utilization of kitchen waste, comprising the following steps:

[0048] S1. The kitchen waste undergoes multi-stage pretreatment, including hot water hydrolysis, to separate heavy impurities, light impurities, and crude oil, resulting in a higher-quality and more easily digestible organic slurry.

[0049] S2. The organic slurry is subjected to hydrolysis acidification and methanogenesis reaction in sequence, and the methanogenesis process is enhanced by adding trace elements to produce biogas.

[0050] S3. Conduct biological desulfurization, storage, and energy utilization of the generated biogas;

[0051] S4. The effluent after anaerobic digestion is subjected to solid-liquid separation to obtain biogas slurry and biogas residue;

[0052] S5. Part of the biogas slurry is recycled to the hydrolysis and acidification step, and the remaining biogas slurry is fermented to produce acid and enrich VFAs. Then, it is subjected to membrane deep treatment to obtain PHA synthesis raw materials, liquid organic fertilizer and recycled water, respectively.

[0053] S6. Mix a portion of the biogas residue with a conditioner and carry out aerobic fermentation to produce solid organic fertilizer or cultivation substrate, and carbonize the other portion to produce biochar.

[0054] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for anaerobic digestion treatment and resource utilization of kitchen waste, characterized in that, The system comprises a pretreatment subsystem, an anaerobic digestion subsystem, a biogas purification and utilization subsystem, and a biogas slurry and residue resource subsystem connected in sequence along the material flow direction, wherein: The pretreatment subsystem is used for impurity separation, pulping, and oil extraction of the incoming kitchen waste; The anaerobic digestion subsystem is used for hydrolysis acidification and methanogenesis of the pretreated organic slurry to produce biogas; The biogas purification and utilization subsystem is used for desulfurization, storage, and energy utilization of the produced biogas; The biogas slurry and residue resource subsystem is used for solid-liquid separation of the effluent after anaerobic digestion, and deep processing and resource utilization of the separated biogas slurry and residue.

2. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 1, characterized in that, The pretreatment subsystem comprises a receiving bin, a crusher, a thermal hydrolysis reactor, a hydrocyclone, a fine-pulping machine, and a horizontal centrifuge connected in sequence; the thermal hydrolysis reactor has an operating pressure of 0.5-1.2 MPa, a temperature of 120-160℃, and a reaction time of 15-40 minutes; the hydrocyclone is used for separating heavy impurities; the fine-pulping machine is provided with a fine grid for separating light impurities and pulping the material; and the horizontal centrifuge is used for extracting crude oil from the slurry.

3. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 2, characterized in that, The pretreatment subsystem further comprises a sand settling tank and a foreign matter removal device arranged between the hydrocyclone and the fine-pulping machine for further removing fine sand and fiber impurities.

4. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 3, characterized in that, The anaerobic digestion subsystem comprises a slurry buffer tank, a hydrolysis acidification tank, and a methanogenesis tank connected in series; the hydrolysis acidification tank is provided with a mechanical stirrer and a heating coil inside to control the reaction temperature at 35-40℃; the methanogenesis tank is a complete-mix anaerobic reactor provided with a three-stage loop water distributor inside and a double-membrane gas storage tank integrated at the top; the methanogenesis tank is further provided with an external circulation pipe network and a trace element automatic feeding device connected with the external circulation pipe network, and the trace elements at least include iron, cobalt, and nickel.

5. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 4, characterized in that, The operating temperature of the methanogenesis tank is controlled at mesophilic 35-38℃ or thermophilic 50-55℃.

6. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 5, characterized in that, The biogas purification and utilization subsystem comprises a biological desulfurization tower, a gas tank, and a biogas utilization unit connected in sequence; and the biogas utilization unit is a combined heat and power unit or a biogas purification and bio-natural gas device.

7. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 6, characterized in that, The biogas slurry and residue resource subsystem comprises a solid-liquid separator, a biogas slurry temporary storage tank connected with the liquid phase outlet of the solid-liquid separator, and a biogas residue buffer bin connected with the solid phase outlet of the solid-liquid separator; the outlet of the biogas slurry temporary storage tank is divided into two routes, one of which is connected to the hydrolysis acidification tank through a reflux pipeline, and the other of which is connected to a biogas slurry deep processing unit; the biogas slurry deep processing unit is a nanofiltration and reverse osmosis membrane system; the concentrated water outlet of the nanofiltration membrane is used to produce liquid organic fertilizer, and the water outlet of the reverse osmosis membrane is used to produce recycled water; the outlet of the biogas residue buffer bin is also divided into two routes, one of which is connected to an aerobic fermentation bin to produce solid organic fertilizer, and the other of which is connected to a carbonization reactor to produce biochar.

8. The kitchen waste anaerobic digestion treatment and resource utilization system according to claim 7, characterized in that, The biogas slurry deep processing unit is further provided with a biogas slurry fermentation and acid production unit before it for enriching volatile fatty acids as raw materials for synthesizing biodegradable plastics.

9. The kitchen waste anaerobic digestion treatment and resource utilization system according to any one of claim 8, characterized in that, The system also comprises an intelligent control subsystem; the intelligent control subsystem comprises sensors deployed at key nodes of the system, a central controller and an actuator; the sensors are used to monitor pH, oxidation-reduction potential, temperature, liquid level, biogas flow and component parameters in real time; the central controller outputs optimized control instructions based on sensor data and in combination with a digital twin model and big data analysis algorithms; and the actuator is used to receive the control instructions and adjust the operating state of the feed pump, the reflux pump, the heating system, the stirring device and the trace element dosing device.

10. A method for anaerobic digestion and resource utilization of kitchen waste, used in a system for anaerobic digestion and resource utilization of kitchen waste according to any one of claims 1-9, characterized in that, The method comprises the following steps: S1, the kitchen waste is subjected to multi-stage pretreatment including thermal hydrolysis, heavy impurities, light impurities and crude grease are separated, and an organic slurry with higher quality and better digestibility is obtained; S2, the organic slurry is subjected to hydrolysis acidification and methanogenesis in sequence, and the methanogenesis process is intensified by adding trace elements, thereby producing biogas; S3, the produced biogas is subjected to biological desulfurization, storage and energy utilization; S4, the effluent after anaerobic digestion is subjected to solid-liquid separation, thereby obtaining biogas slurry and biogas residue; S5, part of the biogas slurry is refluxed to the hydrolysis acidification step, the remaining biogas slurry is subjected to fermentation to enrich VFAs, then subjected to membrane deep treatment, thereby obtaining PHA synthesis raw material, liquid organic fertilizer and recycled water respectively; S6, part of the biogas residue is mixed with a conditioning agent and subjected to aerobic fermentation, thereby producing solid organic fertilizer or cultivation substrate, and the other part is subjected to carbonization treatment, thereby producing biochar.

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