Kitchen wastewater treatment method and system

Abstract

The invention discloses a kitchen wastewater treatment method and system, and relates to the technical field of wastewater treatment.The kitchen wastewater treatment method comprises the steps that S1, pretreatment is conducted, large-particle matter and grease in wastewater are removed, and the water quality and the water quantity are adjusted; s2, carrying out solid-liquid separation, and degrading organic matters by utilizing an anaerobic treatment technology; s3, ammonia nitrogen treatment: removing ammonia nitrogen in the wastewater; and S4, final treatment: further removing nitrogen and other pollutants until emission requirements are met. According to the invention, the kitchen wastewater after pretreatment is treated by adopting a combined anaerobic treatment process of the completely mixed anaerobic reactor and the anaerobic MBR membrane, so that materials in the reactor can be in a completely mixed state, uniform distribution of temperature and pH value is ensured, deposition, scum crusting and concentration difference distribution are avoided, and the quality of kitchen wastewater is improved. Meanwhile, the anaerobic MBR membrane can effectively intercept anaerobic sludge and recycle the anaerobic sludge, so that the defect that the sludge of the kitchen anaerobic reactor is easy to lose is overcome, the sludge concentration and the methane production rate of the anaerobic reactor are improved, and the anaerobic treatment efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method and system for treating kitchen wastewater. Background Art

[0002] With the improvement of social living standards, the problem of food waste pollution has become increasingly serious. The treatment of food waste has also led to the generation of food wastewater, which mainly comes from the water contained in the food waste itself, the water generated during the fermentation process, and the water generated in various processes during the treatment of food waste.

[0003] The current mainstream and common treatment processes for food wastewater are a combination of several or more units, including pretreatment, anaerobic biological treatment, aerobic biological treatment, and membrane technology treatment. Anaerobic and aerobic biological treatment technologies are the core, but these processes also have some defects, as described in the following aspects:

[0004] (1) Stability of anaerobic treatment: Since the organic matter content in food wastewater is high, up to 100,000 mg / L, anaerobic reactors such as UASB are required for pre-treatment. However, some of the oil in food wastewater tends to adhere to the anaerobic sludge, making it difficult for the sludge to settle and thus lost with the water. As time goes by, the amount of sludge lost gradually increases. In addition, the reproduction rate of anaerobic microorganisms is slow, and the number of newly grown anaerobic microorganisms is less than the amount of lost anaerobic microorganisms. This ultimately leads to a decrease in the sludge load in the anaerobic reactor and a decrease in the removal rate, resulting in a higher organic matter load in the subsequent biochemical stage, affecting the treatment effect and treatment stability.

[0005] (2) High investment cost: Due to the high concentration of ammonia nitrogen and organic matter in food wastewater, conventional aerobic biochemical processes generally use two-stage A / O technology. The biochemical pool is designed to have a large capacity and a large number of equipment, resulting in a large project footprint, high civil construction costs, and high investment costs.

[0006] (3) High operating costs: Due to the high concentration of ammonia nitrogen in food wastewater, aerobic biochemical treatment requires a large-power blower to meet the aeration requirements of the nitrification tank: the aeration required for both the organic matter removal reaction and the nitrification reaction needs to be met at the same time. Moreover, since the nitrification tank has sufficient aeration to remove most of the organic matter, the denitrification tank lacks a carbon source, and the original material is difficult to use as a carbon source. At this time, a large amount of additional carbon source needs to be added, which greatly increases the operating cost. In addition, the removal of high-concentration ammonia nitrogen and organic matter leads to a large increase in sludge volume and an increase in sludge disposal costs.

[0007] (4) The effluent water quality fluctuates greatly, and it is difficult to stably meet the discharge standards. The traditional anaerobic plus aerobic biochemical treatment process has poor resistance to shock loads when the system's influent water quality and water volume fluctuate greatly. The effluent water quality is prone to fluctuate, and it is difficult to stably meet the discharge standards. The use of new biological denitrification treatment technologies such as anaerobic ammonia oxidation has high requirements for operation and management, unstable process operation, and it is difficult to guarantee the treatment effect. Summary of the Invention

[0008] The object of the present invention is to provide a method and system for treating kitchen wastewater to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a method for treating kitchen wastewater, comprising the following steps:

[0010] S1: Pretreatment: The kitchen wastewater after oil extraction is sent to the pretreatment unit to remove large particles and grease in the wastewater and adjust the water quality and water volume;

[0011] S2: solid-liquid separation, the produced water obtained in step S1 is sent to a high-efficiency anaerobic treatment unit to degrade organic matter using anaerobic treatment technology;

[0012] S3: Ammonia nitrogen treatment, sending the produced water obtained in step S2 to an ammonia-degassing membrane treatment unit to remove ammonia nitrogen in the wastewater;

[0013] S4: Final treatment: the produced water obtained in step S3 is sent to the MBR membrane treatment unit to further remove nitrogen and other pollutants until it meets the discharge requirements.

[0014] Preferably, the pretreatment unit in step S1 includes a regulating tank, a grease trap and a coagulation flotation tank.

[0015] Preferably, step S1 includes the following steps:

[0016] S11: Sending the oil-extracted kitchen wastewater to the regulating tank to adjust the water quality and water volume;

[0017] S12: The effluent from the regulating tank is sent to the grease trap, where grease is removed from the wastewater by gravity separation;

[0018] S13: The effluent from the grease trap is sent to a coagulation reaction tank, where PAC and PAM are added to form flocs to remove suspended solids;

[0019] S14: The effluent from the coagulation reaction tank enters the coagulation flotation tank, where the flotation technology is used to further remove grease and suspended solids in the water, so that the water quality meets the requirements for entering the high-efficiency anaerobic treatment unit.

[0020] Preferably, in step S2, the high-efficiency anaerobic treatment unit includes a completely mixed anaerobic reactor and an anaerobic MBR membrane tank. The completely mixed anaerobic reactor adopts a mechanical stirring form. The mixed anaerobic reactor is provided with a biogas collecting pipe and a biogas tank for collecting biogas generated by the anaerobic reaction. The anaerobic MBR membrane tank is provided with a sludge return pump for recycling anaerobic sludge. The anaerobic MBR membrane tank is provided with a biogas blower for aerating and flushing the membrane surface. The gas in the biogas tank is used as the gas source for the biogas blower.

[0021] Preferably, step S2 includes the following steps:

[0022] S21: sending the produced water obtained in step S1 into a completely mixed anaerobic reactor, in which the high-concentration organic matter in the food wastewater is degraded by anaerobic microorganisms;

[0023] S22: In a completely mixed anaerobic reactor, mechanical stirring is used to ensure that the wastewater and microorganisms are fully mixed;

[0024] S23: collecting the biogas generated by the anaerobic reaction in the completely mixed anaerobic reactor through the biogas collecting pipe, and at the same time transporting the biogas to the biogas tank for storage;

[0025] S24: The effluent from the completely mixed anaerobic reactor is sent to the anaerobic MBR membrane tank, and the anaerobic sludge is effectively retained by the MBR membrane assembly;

[0026] S25: In the anaerobic MBR membrane tank, part of the sludge is returned to the completely mixed anaerobic reactor through the sludge return pump to maintain the appropriate sludge concentration and reaction effect;

[0027] S26: A biogas blower is used in the anaerobic MBR membrane tank to aerate and flush the membrane surface.

[0028] Preferably, in step S3, the ammonia-degassing membrane treatment unit includes a pH adjustment system, a security filtration system, a temperature control system, an ammonia-degassing membrane system and an acid absorption liquid circulation system connected in sequence. The ammonia-degassing membrane treatment unit first passes the S2 effluent through the pH adjustment system under alkaline conditions to form high-concentration free ammonia wastewater, then blows out ammonia through the ammonia-degassing membrane, and finally is absorbed by the acid absorption liquid circulation system to form an ammonium sulfate solution with a mass concentration of 10% to 40%.

[0029] Preferably, step S3 includes the following steps:

[0030] S31: sending the produced water obtained in step S2 into a pH adjustment system, and adjusting the pH value of the water to an alkaline condition by adding alkaline substances to promote the generation of free ammonia;

[0031] S32: The wastewater after pH adjustment is sent to the security filtration system to remove suspended matter and solid impurities in the water through filtration;

[0032] S33: Send the filtered water to the temperature control system to adjust the water temperature so that the wastewater can be removed from ammonia within a suitable temperature range;

[0033] S34: The conditioned wastewater is fed into an ammonia-degassing membrane system, where ammonia in the wastewater is effectively blown off into the gas phase through membrane separation technology;

[0034] S35: After the ammonia is removed, it passes through the acid absorption liquid circulation system, where the acid absorption liquid absorbs the ammonia to form an ammonium sulfate solution with a concentration of 10% to 40%.

[0035] Preferably, in step S4, the MBR membrane treatment unit includes a denitrification tank, a nitrification tank, and an MBR membrane tank connected in sequence. The denitrification tank and the nitrification tank are provided with nitrification liquid reflux, and the reflux ratio is 200% to 1000%. The reflux ratio of the MBR membrane tank is 200% to 1000%.

[0036] Preferably, step S4 includes the following steps:

[0037] S41: sending the produced water obtained in step S3 into a denitrification tank, where a denitrification reaction is carried out under anaerobic conditions;

[0038] S42: The effluent from the denitrification tank is sent to the nitrification tank, where ammonia nitrogen is converted into nitrate nitrogen by nitrifying bacteria through nitrification reaction under aerobic conditions;

[0039] S43: setting a nitrification liquid reflux system in the nitrification tank to return part of the effluent to the denitrification tank through a reflux pipe, with the reflux ratio set at 200% to 1000%;

[0040] S44: The effluent from the nitrification tank is sent to the MBR membrane tank, and the suspended solids and microorganisms in the water are effectively intercepted by the MBR membrane components;

[0041] S45: A sludge return pump is provided in the MBR membrane tank to return part of the sludge in the membrane tank to the nitrification tank, and the return ratio is set to 200% to 1000%;

[0042] S46: Carry out water quality monitoring and monitor the effluent from the MBR membrane pool until it meets the discharge standards.

[0043] The present invention also provides a system for treating kitchen wastewater, comprising:

[0044] The pretreatment module sends the oil-extracted kitchen wastewater to the pretreatment unit to remove large particles and grease in the wastewater and adjust the water quality and water volume;

[0045] The solid-liquid separation module sends the produced water obtained from the pretreatment module to the high-efficiency anaerobic treatment unit, which uses anaerobic treatment technology to degrade organic matter;

[0046] The ammonia nitrogen treatment module sends the produced water obtained from the solid-liquid separation module to the ammonia-degassing membrane treatment unit to remove ammonia nitrogen from the wastewater;

[0047] The final treatment module sends the produced water obtained from the ammonia nitrogen treatment module to the MBR membrane treatment unit to further remove nitrogen and other pollutants until it meets the emission requirements.

[0048] The technical effects and advantages of the present invention are as follows:

[0049] (1) The present invention uses a combined anaerobic treatment process of a completely mixed anaerobic reactor and an anaerobic MBR membrane to treat pretreated food wastewater. The anaerobic combined process can keep the materials in the reactor in a completely mixed state, ensure uniform temperature and pH distribution, avoid sedimentation, scum crusting and concentration distribution, and at the same time, the anaerobic MBR membrane can effectively intercept anaerobic sludge and recycle it, solving the problem of easy loss of sludge in the anaerobic food reactor, increasing the sludge concentration and biogas production rate of the anaerobic reactor, and improving the anaerobic treatment efficiency;

[0050] (2) The present invention adopts an ammonia-degassing membrane treatment unit, which greatly reduces the subsequent ammonia nitrogen treatment load, adjusts a reasonable carbon-nitrogen ratio, improves the stability of the subsequent biochemical treatment effect, and reduces aeration energy consumption and the amount of external carbon source added;

[0051] (3) The present invention adopts a one-stage A / O-MBR system, which reduces the floor space of the structure, reduces the civil construction cost and equipment investment cost, reduces the organic load and ammonia nitrogen load of biochemical treatment, reduces the sludge production, effectively saves the sludge disposal cost, and the MBR membrane treatment process greatly improves the solid-liquid separation efficiency and the stability of the effluent water quality, and finally the effluent meets the national emission standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart of a method for treating kitchen wastewater according to the present invention.

[0053] Figure 2 This is a pre-processing flow chart of step S1 of the present invention.

[0054] Figure 3 This is a flow chart of solid-liquid separation in step S2 of the present invention.

[0055] Figure 4 This is a flow chart of ammonia nitrogen treatment in step S3 of the present invention.

[0056] Figure 5 This is a flowchart of the final processing of step S4 of the present invention.

[0057] Figure 6 This is a block diagram of a kitchen wastewater treatment system according to the present invention. DETAILED DESCRIPTION

[0058] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0059] The present invention provides Figure 1-6 A method for treating kitchen wastewater shown includes the following steps:

[0060] S1: Pretreatment: The kitchen wastewater after oil extraction is sent to the pretreatment unit to remove large particles and grease in the wastewater and adjust the water quality and water volume;

[0061] S2: solid-liquid separation, the produced water obtained in step S1 is sent to a high-efficiency anaerobic treatment unit to degrade organic matter using anaerobic treatment technology;

[0062] S3: Ammonia nitrogen treatment, sending the produced water obtained in step S2 to an ammonia-degassing membrane treatment unit to remove ammonia nitrogen in the wastewater;

[0063] S4: Final treatment: the produced water obtained in step S3 is sent to the MBR membrane treatment unit to further remove nitrogen and other pollutants until it meets the discharge requirements.

[0064] The pretreated food wastewater is treated by an anaerobic treatment process combining a completely mixed anaerobic reactor and an anaerobic MBR membrane. This anaerobic combination process can keep the materials in the reactor in a completely mixed state, ensure uniform temperature and pH distribution, avoid sedimentation, scum crusting and concentration distribution. At the same time, the anaerobic MBR membrane can effectively intercept anaerobic sludge and recycle it, solving the defect of easy loss of sludge in the anaerobic food reactor, increasing the sludge concentration and biogas production rate of the anaerobic reactor, and improving the anaerobic treatment efficiency, reducing the organic matter treatment load of the subsequent aerobic biochemical unit.

[0065] The pretreatment unit in step S1 includes a regulating tank, a grease trap and a coagulation flotation tank.

[0066] Step S1 includes the following steps:

[0067] S11: The oil-extracted food wastewater is sent to the regulating tank to adjust the water quality and water volume. This prevents load changes in subsequent treatment units caused by water quality fluctuations or sudden increases in water volume, ensuring stable operation of the system. During the water intake process, the regulating tank also helps to precipitate some larger solid particles.

[0068] S12: The effluent from the regulating tank is sent to the grease trap, where grease is removed from the wastewater by gravity separation. Gravity separation effectively removes floating oil and grease from the wastewater, reducing the impact of grease on subsequent treatment units and preventing grease from inhibiting microorganisms in the anaerobic reactor. After grease removal, the water quality is improved, which helps to improve the efficiency of subsequent treatment;

[0069] S13: The effluent from the grease trap is sent to a coagulation reaction tank, where PAC and PAM are added to form flocs to remove suspended solids. The formation of flocs can settle the suspended solids, improve the clarity of the water, and meet the requirements of subsequent treatment;

[0070] S14: The effluent from the coagulation reaction tank enters the coagulation flotation tank, where flotation technology is used to further remove grease and suspended solids in the water, ensuring that the water quality meets the requirements for entering the high-efficiency anaerobic treatment unit. Flotation technology can further remove tiny grease and suspended solids in the water on the basis of coagulation reaction, ensuring that the water quality meets the requirements of the high-efficiency anaerobic treatment unit, improving the overall wastewater treatment efficiency and reducing the burden on subsequent treatment units.

[0071] In step S2, the high-efficiency anaerobic treatment unit includes a completely mixed anaerobic reactor and an anaerobic MBR membrane tank. The completely mixed anaerobic reactor adopts mechanical stirring. The mixed anaerobic reactor is provided with a biogas collecting pipe and a biogas tank for collecting biogas generated by the anaerobic reaction. The anaerobic MBR membrane tank is provided with a sludge return pump for recycling anaerobic sludge. The anaerobic MBR membrane tank is provided with a biogas blower for aerating and flushing the membrane surface. The gas in the biogas tank is used as the gas source of the biogas blower.

[0072] Step S2 includes the following steps:

[0073] S21: The produced water obtained in step S1 is fed into a completely mixed anaerobic reactor. In this reactor, the high-concentration organic matter in the food wastewater is degraded by anaerobic microorganisms. The anaerobic microorganisms can efficiently degrade the high-concentration organic matter in the food wastewater in an oxygen-deficient environment, converting it into biogas and other metabolites. Through biodegradation, the organic matter content in the wastewater is reduced, thereby reducing the wastewater volume;

[0074] S22: In a completely mixed anaerobic reactor, mechanical stirring is used to ensure that the wastewater and microorganisms are fully mixed. Mechanical stirring can ensure that the wastewater and microorganisms are fully in contact, improve the degradation efficiency of microorganisms, and stir to evenly distribute the substances in the reactor, avoid sedimentation and dead zones, and improve the overall performance of the reactor;

[0075] S23: In the completely mixed anaerobic reactor, biogas generated by the anaerobic reaction is collected through a biogas collecting pipe and transported to a biogas tank for storage. By collecting the biogas generated by the anaerobic reaction, energy recovery can be performed. The biogas can be used for power generation or as fuel, thereby reducing processing costs.

[0076] S24: The effluent from the completely mixed anaerobic reactor is sent to the anaerobic MBR membrane tank, where the anaerobic sludge is effectively intercepted by the MBR membrane assembly. The MBR membrane assembly can effectively intercept anaerobic sludge and microorganisms, ensuring the clarity of the effluent and reducing suspended solids in the effluent.

[0077] S25: In the anaerobic MBR membrane tank, part of the sludge is returned to the completely mixed anaerobic reactor through the sludge return pump to maintain the appropriate sludge concentration and reaction effect. Part of the sludge is returned to the completely mixed anaerobic reactor through the sludge return pump to ensure that there is enough activated sludge in the reactor to maintain the appropriate sludge concentration and reaction effect.

[0078] S26: In the anaerobic MBR membrane tank, the biogas fan is used to aerate and flush the membrane surface, which can effectively prevent membrane pollution and blockage and extend the service life of the membrane.

[0079] In step S3, the ammonia-degassing membrane treatment unit includes a pH adjustment system, a security filtration system, a temperature control system, an ammonia-degassing membrane system and an acid absorption liquid circulation system connected in sequence. The ammonia-degassing membrane treatment unit first passes the S2 effluent through the pH adjustment system under alkaline conditions to form high-concentration free ammonia wastewater, then blows out ammonia through the ammonia-degassing membrane, and finally is absorbed by the acid absorption liquid circulation system to form an ammonium sulfate solution with a mass concentration of 10% to 40%, which greatly reduces the subsequent ammonia nitrogen treatment load, adjusts a reasonable carbon-nitrogen ratio, improves the stability of the subsequent biochemical treatment effect, and reduces aeration energy consumption and the amount of external carbon source added.

[0080] Step S3 includes the following steps:

[0081] S31: The produced water obtained in step S2 is fed into a pH adjustment system, where the pH value of the water is adjusted to an alkaline condition by adding an alkaline substance to promote the generation of free ammonia. Under alkaline conditions, the volatility of ammonia is enhanced, which helps to effectively remove ammonia from the water through the degassing membrane system later;

[0082] S32: The wastewater after pH adjustment is sent to the security filtration system to remove suspended matter and solid impurities in the water through filtration to avoid clogging and damage to subsequent equipment;

[0083] S33: The filtered water is sent to the temperature control system to adjust the water temperature so that the wastewater can be removed from ammonia within a suitable temperature range. The suitable temperature can accelerate chemical and biological reactions and improve the overall efficiency of ammonia removal.

[0084] S34: The conditioned wastewater is fed into the ammonia-degassing membrane system. Through membrane separation technology, ammonia in the wastewater is effectively blown off into the gas phase. The membrane technology has high selectivity and high permeability, which can effectively separate ammonia and ensure removal effect.

[0085] S35: After the ammonia is removed, it passes through the acid absorption liquid circulation system, where the acid absorption liquid absorbs the ammonia to form an ammonium sulfate solution with a concentration of 10% to 40%, which can convert the ammonia into useful chemicals for subsequent processing and utilization.

[0086] In step S4, the MBR membrane treatment unit includes a denitrification tank, a nitrification tank, and an MBR membrane tank connected in sequence. The denitrification tank and the nitrification tank are provided with nitrification liquid reflux, and the reflux ratio is 200% to 1000%. The MBR membrane tank has a reflux ratio of 200% to 1000%.

[0087] Step S4 includes the following steps:

[0088] S41: The produced water obtained in step S3 is sent to a denitrification tank, where a denitrification reaction is carried out under anaerobic conditions. Denitrifying bacteria convert nitrate nitrogen into nitrogen gas, thereby reducing the nitrogen content in the water and releasing the nitrogen into the atmosphere in the form of gas, thereby reducing nitrogen accumulation in the water body and reducing water pollution;

[0089] S42: The effluent from the denitrification tank is fed into the nitrification tank, where ammonia nitrogen is converted into nitrate nitrogen through nitrification reaction under aerobic conditions using nitrifying bacteria. The nitrification reaction not only removes ammonia nitrogen but also improves water quality and reduces environmental impact.

[0090] S43: A nitrification liquid reflux system is set in the nitrification tank to return part of the effluent to the denitrification tank through a reflux pipe. The reflux ratio is set to 200% to 1000%. By returning part of the nitrification tank effluent to the denitrification tank, more nitrate nitrogen can be provided as a substrate for the denitrification reaction, thereby promoting nitrogen removal.

[0091] S44: The effluent from the nitrification tank is sent to the MBR membrane tank, where the MBR membrane components effectively intercept the suspended solids and microorganisms in the water. The MBR membrane components can effectively intercept the suspended solids and microorganisms in the water, ensuring the clarity of the effluent and reducing pollutants in the effluent;

[0092] S45: A sludge return pump is provided in the MBR membrane tank to return part of the sludge in the membrane tank to the nitrification tank. The return ratio is set at 200% to 1000%. By returning part of the sludge in the membrane tank to the nitrification tank, sufficient activated sludge is ensured in the nitrification reactor to improve the reaction efficiency.

[0093] S46: Carry out water quality monitoring, monitor the effluent from the MBR membrane pool, and discharge it until it meets the discharge standards. Regular water quality monitoring can prevent pollution to the environment.

[0094] The present invention also provides a system for treating kitchen wastewater, comprising:

[0095] The pretreatment module sends the oil-extracted kitchen wastewater to the pretreatment unit to remove large particles and grease in the wastewater and adjust the water quality and water volume;

[0096] The solid-liquid separation module sends the produced water obtained from the pretreatment module to the high-efficiency anaerobic treatment unit, which uses anaerobic treatment technology to degrade organic matter;

[0097] The ammonia nitrogen treatment module sends the produced water obtained from the solid-liquid separation module to the ammonia-degassing membrane treatment unit to remove ammonia nitrogen from the wastewater;

[0098] The final treatment module sends the produced water obtained from the ammonia nitrogen treatment module to the MBR membrane treatment unit to further remove nitrogen and other pollutants until it meets the emission requirements.

[0099] The food wastewater treatment system uses four modules: pretreatment, solid-liquid separation, ammonia nitrogen treatment, and final treatment. It gradually removes large particles, grease, organic matter, and ammonia nitrogen from the wastewater, ensuring that the effluent quality meets emission standards. This not only effectively reduces the environmental burden and the risk of water pollution, but also recycles resources such as biogas and ammonia, increases water reuse rates, and optimizes water resource management.

[0100] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for treating kitchen wastewater, characterized in that: The following steps are involved: S1: Pretreatment: The kitchen wastewater after oil extraction is sent to the pretreatment unit to remove large particles and grease in the wastewater and adjust the water quality and water volume; S2: solid-liquid separation, the produced water obtained in step S1 is sent to a high-efficiency anaerobic treatment unit to degrade organic matter using anaerobic treatment technology; S3: Ammonia nitrogen treatment, sending the produced water obtained in step S2 to an ammonia-degassing membrane treatment unit to remove ammonia nitrogen in the wastewater; S4: Final treatment: the produced water obtained in step S3 is sent to the MBR membrane treatment unit to further remove nitrogen and other pollutants until it meets the discharge requirements.

2. The method for treating kitchen wastewater according to claim 1, wherein: The pretreatment unit in step S1 includes a regulating tank, a grease trap and a coagulation flotation tank.

3. The method for treating kitchen wastewater according to claim 2, wherein: The step S1 comprises the following steps: S11: Sending the oil-extracted kitchen wastewater to the regulating tank to adjust the water quality and water volume; S12: The effluent from the regulating tank is sent to the grease trap, where grease is removed from the wastewater by gravity separation; S13: The effluent from the grease trap is sent to a coagulation reaction tank, where PAC and PAM are added to form flocs to remove suspended solids; S14: The effluent from the coagulation reaction tank enters the coagulation flotation tank, where the flotation technology is used to further remove grease and suspended solids in the water, so that the water quality meets the requirements for entering the high-efficiency anaerobic treatment unit.

4. The method for treating kitchen wastewater according to claim 1, wherein: In step S2, the high-efficiency anaerobic treatment unit includes a completely mixed anaerobic reactor and an anaerobic MBR membrane tank. The completely mixed anaerobic reactor adopts a mechanical stirring form. The mixed anaerobic reactor is provided with a biogas collecting pipe and a biogas tank for collecting biogas generated by the anaerobic reaction. The anaerobic MBR membrane tank is provided with a sludge return pump for recycling anaerobic sludge. The anaerobic MBR membrane tank is provided with a biogas blower for aerating and flushing the membrane surface. The gas in the biogas tank is used as the gas source of the biogas blower.

5. The method for treating kitchen wastewater according to claim 4, characterized in that: The step S2 comprises the following steps: S21: sending the produced water obtained in step S1 into a completely mixed anaerobic reactor, in which the high-concentration organic matter in the food wastewater is degraded by anaerobic microorganisms; S22: In a completely mixed anaerobic reactor, mechanical stirring is used to ensure that the wastewater and microorganisms are fully mixed; S23: collecting the biogas generated by the anaerobic reaction in the completely mixed anaerobic reactor through the biogas collecting pipe, and at the same time transporting the biogas to the biogas tank for storage; S24: The effluent from the completely mixed anaerobic reactor is sent to the anaerobic MBR membrane tank, and the anaerobic sludge is effectively retained by the MBR membrane assembly; S25: In the anaerobic MBR membrane tank, part of the sludge is returned to the completely mixed anaerobic reactor through the sludge return pump to maintain the appropriate sludge concentration and reaction effect; S26: A biogas blower is used in the anaerobic MBR membrane tank to aerate and flush the membrane surface.

6. The method for treating kitchen wastewater according to claim 1, characterized in that: In step S3, the ammonia-degassing membrane treatment unit includes a pH adjustment system, a security filtration system, a temperature control system, an ammonia-degassing membrane system and an acid absorption liquid circulation system connected in sequence. The ammonia-degassing membrane treatment unit first passes the S2 effluent through the pH adjustment system under alkaline conditions to form high-concentration free ammonia wastewater, then blows out ammonia through the ammonia-degassing membrane, and finally is absorbed by the acid absorption liquid circulation system to form an ammonium sulfate solution with a mass concentration of 10% to 40%.

7. The method for treating kitchen wastewater according to claim 6, characterized in that: The step S3 comprises the following steps: S31: sending the produced water obtained in step S2 into a pH adjustment system, and adjusting the pH value of the water to an alkaline condition by adding alkaline substances to promote the generation of free ammonia; S32: The wastewater after pH adjustment is sent to the security filtration system to remove suspended matter and solid impurities in the water through filtration; S33: Send the filtered water to the temperature control system to adjust the water temperature so that the wastewater can be removed from ammonia within a suitable temperature range; S34: The conditioned wastewater is fed into an ammonia-degassing membrane system, where ammonia in the wastewater is effectively blown off into the gas phase through membrane separation technology; S35: After the ammonia is removed, it passes through the acid absorption liquid circulation system, where the acid absorption liquid absorbs the ammonia to form an ammonium sulfate solution with a concentration of 10% to 40%.

8. The method for treating kitchen wastewater according to claim 1, wherein: In step S4, the MBR membrane treatment unit includes a denitrification tank, a nitrification tank, and an MBR membrane tank connected in sequence. The denitrification tank and the nitrification tank are provided with nitrification liquid reflux, and the reflux ratio is 200% to 1000%. The reflux ratio of the MBR membrane tank is also 200% to 1000%.

9. The method for treating kitchen wastewater according to claim 8, characterized in that: The step S4 comprises the following steps: S41: sending the produced water obtained in step S3 into a denitrification tank, where a denitrification reaction is carried out under anaerobic conditions; S42: The effluent from the denitrification tank is sent to the nitrification tank, where ammonia nitrogen is converted into nitrate nitrogen by nitrifying bacteria through nitrification reaction under aerobic conditions; S43: setting a nitrification liquid reflux system in the nitrification tank to return part of the effluent to the denitrification tank through a reflux pipe, with the reflux ratio set at 200% to 1000%; S44: The effluent from the nitrification tank is sent to the MBR membrane tank, and the suspended solids and microorganisms in the water are effectively intercepted by the MBR membrane components; S45: A sludge return pump is provided in the MBR membrane tank to return part of the sludge in the membrane tank to the nitrification tank, and the return ratio is set to 200% to 1000%; S46: Carry out water quality monitoring and monitor the effluent from the MBR membrane pool until it meets the discharge standards.

10. A system for treating food wastewater, implementing a method for treating food wastewater according to any one of claims 1 to 9, characterized in that: include: The pretreatment module sends the oil-extracted kitchen wastewater to the pretreatment unit to remove large particles and grease in the wastewater and adjust the water quality and water volume; The solid-liquid separation module sends the produced water obtained from the pretreatment module to the high-efficiency anaerobic treatment unit, which uses anaerobic treatment technology to degrade organic matter; The ammonia nitrogen treatment module sends the produced water obtained from the solid-liquid separation module to the ammonia-degassing membrane treatment unit to remove ammonia nitrogen from the wastewater; The final treatment module sends the produced water obtained from the ammonia nitrogen treatment module to the MBR membrane treatment unit to further remove nitrogen and other pollutants until it meets the emission requirements.

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