Low-cost nitrogen and phosphorus removal treatment process for kitchen treatment sewage

Abstract

The invention provides a low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater, belongs to the technical field of kitchen wastewater treatment, and aims to overcome the defects that an existing nitrogen and phosphorus removal process for kitchen wastewater is long in flow, high in energy consumption, high in cost, unstable in effect and the like. According to the process, a combined process of pretreatment, short-cut nitrification, anaerobic ammonium oxidation and chemical auxiliary phosphorus removal is adopted, modified suspended filler, an anaerobic ammonium oxidation bacteria immobilized carrier and a modified fly ash composite phosphorus removal agent are matched, and intermediate water quality regulation and sludge backflow design is combined. The method realizes efficient and synchronous removal of nitrogen and phosphorus, simplifies the process flow, reduces energy consumption and medicament cost, improves operation stability, adapts to the characteristics of water quality fluctuation of kitchen sewage, and is high in practicability.

Description

Technical Field

[0001] This invention relates to the field of kitchen wastewater treatment technology, specifically to a low-cost nitrogen and phosphorus removal process for kitchen wastewater. Background Technology

[0002] Kitchen wastewater contains large amounts of organic matter and high concentrations of nitrogen and phosphorus pollutants, and its quality and quantity fluctuate greatly, making it one of the most challenging aspects of wastewater treatment. Existing nitrogen and phosphorus removal processes often combine traditional nitrification and denitrification technologies with chemical phosphorus removal, resulting in lengthy processes, high energy consumption, and large reagent consumption. For example, Chinese invention patent CN114620900A discloses a method for denitrifying anaerobic kitchen wastewater. This method involves filtration to remove oil, mixing in an equalization tank, treatment in a biological denitrification reactor, followed by discharge through multi-stage anoxic tanks, aerobic aeration tanks, and an MBR membrane bioreactor. While it achieves a certain level of denitrification, it suffers from numerous process steps, requires the addition of denitrifying bacteria and acidified hydrolysate to adjust the carbon-to-nitrogen ratio, leading to high operating costs. Furthermore, it does not offer a solution for the efficient and low-cost removal of phosphorus pollutants. In addition, traditional nitrification-denitrification processes require complete nitrification and denitrification stages, resulting in long retention times and high aeration energy consumption due to the numerous reaction steps. Chemical phosphorus removal commonly uses conventional agents such as aluminum and iron salts, which are costly and generate large amounts of chemical sludge. Furthermore, the coupling stability of short-cut nitrification and anaerobic ammonium oxidation in existing processes is poor, making it difficult to adapt to fluctuations in the water quality of kitchen wastewater. Moreover, phosphorus removal agents are mostly specialized chemicals, failing to achieve resource utilization of industrial waste, further increasing treatment costs. In addition, some processes lack precise control over key reaction stages, leading to unstable nitrogen and phosphorus removal effects and difficulty in meeting emission standards. Therefore, this application proposes a simplified, low-cost, and highly efficient and stable nitrogen and phosphorus removal process for kitchen wastewater. Summary of the Invention

[0003] The present invention aims to solve the problems mentioned in the background art by providing a low-cost nitrogen and phosphorus removal process for kitchen wastewater.

[0004] The specific technical solution is as follows:

[0005] A low-cost nitrogen and phosphorus removal process for kitchen wastewater includes the following steps:

[0006] Step 1, pretreatment: introduce kitchen wastewater into the bar screen filter unit to remove suspended impurities, and then enter the equalization tank for water quality and quantity adjustment, controlling the pH of the effluent from the equalization tank to 6.8-7.8 and the water temperature to 22-32℃;

[0007] Step 2, short-cut nitrification: The effluent from the equalization tank is introduced into the short-cut nitrification reactor, and modified suspended packing is added to the reactor. The dissolved oxygen concentration in the reactor is controlled at 0.8-1.5 mg / L, and the hydraulic retention time is 4-6 h to achieve the conversion of ammonia nitrogen to nitrite nitrogen, with a nitrite conversion rate of not less than 85%.

[0008] Step 3, anaerobic ammonia oxidation: The effluent from the short-cut nitrification reactor is introduced into the anaerobic ammonia oxidation reactor. The reactor is filled with an immobilized carrier of anaerobic ammonia oxidizing bacteria. The pH in the reactor is controlled at 7.5-8.3 and the hydraulic retention time is 8-12 hours. Under anaerobic conditions, ammonia nitrogen and nitrite nitrogen are removed simultaneously.

[0009] Step four, chemical-assisted phosphorus removal: introduce the effluent from the anaerobic ammonia oxidation reactor into the phosphorus removal reaction tank, add modified fly ash composite phosphorus removal agent into the tank, control the agent dosage to be 15-25 times the total phosphorus mass in the wastewater, stir and react for 20-30 minutes, then enter the sedimentation tank for solid-liquid separation, the effluent from the sedimentation tank is the qualified effluent.

[0010] The above-mentioned low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater includes a grid filter unit in step one with a grid aperture of 1-3 mm and a stirring device in the equalization tank with a stirring rate of 60-100 r / min.

[0011] In the aforementioned low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater, the modified suspended packing material in step two is made of polyurethane foam modified with iron ions. The packing material filling rate is 30-40% of the effective volume of the reactor, and the sludge concentration in the reactor is controlled at 3000-5000 mg / L.

[0012] In the aforementioned low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater, the anaerobic ammonia oxidizing bacteria immobilization carrier in step three is a sodium alginate-polyvinyl alcohol composite carrier with a particle size of 3-5 mm and an inoculation amount of anaerobic ammonia oxidizing bacteria of 5-8 g / L.

[0013] The aforementioned low-cost nitrogen and phosphorus removal process for kitchen wastewater includes an upflow reactor in step three, where a water distribution device is installed at the bottom of the reactor with a water distribution rate of 0.5-1.0 m / h to ensure uniform water flow.

[0014] The above-mentioned low-cost nitrogen and phosphorus removal process for kitchen wastewater includes a step four method for preparing the modified fly ash composite phosphorus removal agent as follows: fly ash and ferrous sulfate are mixed at a mass ratio of 10:1, calcined at 500-600℃ for 2-3 hours, pulverized to a particle size of less than 100 mesh, and then mixed evenly with zeolite powder at a mass ratio of 8:2.

[0015] The aforementioned low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater includes a pH online monitoring and adjustment device installed in the phosphorus removal reaction tank in step four, which controls the pH of the reaction system to 7.0-7.5 in real time and the stirring rate to 80-120 r / min.

[0016] The aforementioned low-cost nitrogen and phosphorus removal process for kitchen wastewater treatment also includes a sludge return step, in which part of the sludge generated in the sedimentation tank is returned to the short-cut nitrification reactor at a return ratio of 30-50%, and the remaining sludge is treated in the sludge thickening tank.

[0017] The aforementioned low-cost nitrogen and phosphorus removal process for kitchen wastewater includes a sludge thickening tank that uses gravity thickening for 12-24 hours, resulting in sludge moisture content of 85-90% after thickening.

[0018] The aforementioned low-cost nitrogen and phosphorus removal process for kitchen wastewater includes an intermediate water tank between the short-cut nitrification reactor and the anaerobic ammonia oxidation reactor. A water quality monitoring device is installed in the intermediate water tank to monitor the concentrations of nitrite nitrogen and ammonia nitrogen in real time, ensuring that the molar ratio of nitrite nitrogen to ammonia nitrogen entering the anaerobic ammonia oxidation reactor is 1.0-1.3:1.

[0019] The present invention has the following beneficial effects:

[0020] This process achieves efficient and stable treatment of nitrogen and phosphorus removal from kitchen wastewater and cost control through a combined design of pretreatment, short-cut nitrification, anaerobic ammonia oxidation, and chemical-assisted phosphorus removal, along with sludge recirculation and intermediate water quality control. The pretreatment unit effectively intercepts impurities and homogenizes water quality, preventing blockages and water quality shocks in subsequent reaction units, thus laying the foundation for stable operation of the overall process. The coupling of the short-cut nitrification reactor and the anaerobic ammonia oxidation reactor eliminates some steps in traditional nitrification-denitrification processes, reducing aeration energy consumption and carbon source addition requirements. Simultaneously, the selection of modified suspended packing and immobilized carriers for anaerobic ammonia oxidation bacteria enhances the retention capacity and reaction efficiency of functional microorganisms, ensuring stable nitrogen removal. The application of modified fly ash composite phosphorus removal agent realizes the resource utilization of industrial waste, significantly reducing costs compared to conventional chemical phosphorus removal agents while improving the stability of phosphorus removal. The design of the water quality monitoring device and sludge return system in the intermediate pool further optimizes reaction conditions and enhances the process's resistance to water quality fluctuations. The application of the gravity thickener reduces energy consumption and costs for sludge disposal.

[0021] Overall, the process, through the synergistic function of each unit, not only achieves efficient removal of nitrogen and phosphorus pollutants, adapting to the treatment needs of kitchen wastewater with large fluctuations in water quality and high nitrogen and phosphorus concentrations, but also significantly reduces treatment costs through process simplification, selection of low-cost reagents, and energy conservation. At the same time, sludge return and concentration treatment improve the environmental friendliness and operational stability of the process, avoid secondary pollution, and have good economic efficiency and practicality, making it suitable for large-scale promotion and application. Attached Figure Description

[0022] Figure 1 A flowchart of a low-cost nitrogen and phosphorus removal process for kitchen wastewater provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0026] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Example

[0028] The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater provided in this embodiment is as follows: Figure 1 As shown, it includes the following steps:

[0029] Step 1, pretreatment: introduce kitchen wastewater into the bar screen filter unit to remove suspended impurities, and then enter the equalization tank for water quality and quantity adjustment, controlling the pH of the effluent from the equalization tank to 6.8-7.8 and the water temperature to 22-32℃;

[0030] Step 2, short-cut nitrification: The effluent from the equalization tank is introduced into the short-cut nitrification reactor, and modified suspended packing is added to the reactor. The dissolved oxygen concentration in the reactor is controlled at 0.8-1.5 mg / L, and the hydraulic retention time is 4-6 h to achieve the conversion of ammonia nitrogen to nitrite nitrogen, with a nitrite conversion rate of not less than 85%.

[0031] Step 3, anaerobic ammonia oxidation: The effluent from the short-cut nitrification reactor is introduced into the anaerobic ammonia oxidation reactor. The reactor is filled with an immobilized carrier of anaerobic ammonia oxidizing bacteria. The pH in the reactor is controlled at 7.5-8.3 and the hydraulic retention time is 8-12 hours. Under anaerobic conditions, ammonia nitrogen and nitrite nitrogen are removed simultaneously.

[0032] Step four, chemical-assisted phosphorus removal: introduce the effluent from the anaerobic ammonia oxidation reactor into the phosphorus removal reaction tank, add modified fly ash composite phosphorus removal agent into the tank, control the agent dosage to be 15-25 times the total phosphorus mass in the wastewater, stir and react for 20-30 minutes, then enter the sedimentation tank for solid-liquid separation, the effluent from the sedimentation tank is the qualified effluent.

[0033] This solution employs a combined process design of pretreatment, short-cut nitrification, anaerobic ammonium oxidation, and chemically assisted phosphorus removal. Pretreatment ensures the subsequent reaction system is free from interference from suspended impurities, laying the foundation for stable reactions. The coupling of short-cut nitrification and anaerobic ammonium oxidation eliminates some steps in traditional nitrification-denitrification processes, reducing energy and reagent consumption. The use of modified fly ash composite phosphorus removal agents enables the resource utilization of industrial waste, lowering phosphorus removal costs. The overall process forms a synergistic nitrogen and phosphorus removal system, efficiently removing nitrogen and phosphorus pollutants while significantly reducing treatment costs through process simplification and the selection of low-cost reagents. It is suitable for treating kitchen wastewater with large fluctuations in water quality and high nitrogen and phosphorus concentrations.

[0034] Specifically, in this embodiment, the mesh size of the bar filter unit in step one is 1-3 mm, and a stirring device is installed in the equalization tank with a stirring rate of 60-100 r / min. This approach, by clearly defining the bar mesh size and the stirring parameters of the equalization tank, can improve the removal accuracy of suspended impurities in the pretreatment stage, preventing fine impurities from entering subsequent reactors and causing blockages or adhesion contamination. The stirring device promotes uniform mixing of water quality in the equalization tank, reducing the impact of water quality and quantity fluctuations on subsequent reactions, further ensuring the stability of the entire process operation, and creating more controllable influent conditions for subsequent nitrification and ammonia oxidation reactions.

[0035] Specifically, in this embodiment, the modified suspended packing material in step two is made of polyurethane foam modified with iron ions. The packing material filling rate is 30-40% of the effective volume of the reactor, and the sludge concentration in the reactor is controlled at 3000-5000 mg / L. The selection of modified suspended packing material in this scheme, after iron ion modification, can enhance the adsorption and fixation capacity of the packing material for microorganisms, and increase the retention of functional microorganisms in the reactor. Reasonable packing material filling rate and sludge concentration control can optimize the mass transfer environment in the reactor, strengthen the contact reaction between microorganisms and pollutants in the wastewater, thereby improving the short-cut nitrification efficiency, accelerating the conversion of ammonia nitrogen to nitrite nitrogen, and simultaneously enhancing the short-cut nitrification reactor's resistance to water quality fluctuations.

[0036] Specifically, in this embodiment, the anaerobic ammonia oxidizing bacteria immobilization carrier in step three is a sodium alginate-polyvinyl alcohol composite carrier with a particle size of 3-5 mm and an inoculation amount of anaerobic ammonia oxidizing bacteria of 5-8 g / L. This method uses a sodium alginate-polyvinyl alcohol composite carrier to immobilize anaerobic ammonia oxidizing bacteria, which can reduce the loss of anaerobic ammonia oxidizing bacteria and ensure the stability of the functional bacterial population within the reactor. The particle size design of the carrier optimizes the water flow and mass transfer conditions within the reactor, promoting sufficient contact between the anaerobic ammonia oxidizing bacteria and the substrate, thereby ensuring the stability of the simultaneous removal of ammonia nitrogen and nitrite nitrogen, and improving the efficiency and reliability of the anaerobic ammonia oxidation reaction.

[0037] Specifically, in this embodiment, the anaerobic ammonia oxidation reactor in step three is an upflow reactor with a water distribution device at the bottom of the reactor. The water distribution rate is 0.5-1.0 m / h to ensure uniform water flow. This design of the anaerobic ammonia oxidation reactor as an upflow reactor, coupled with a bottom water distribution device, facilitates the retention and growth of bacteria within the reactor. Uniform water distribution at the bottom avoids localized short-circuiting of the water flow, ensuring sufficient contact between the wastewater and the immobilized carrier of the anaerobic ammonia oxidizing bacteria, improving reaction mass transfer efficiency, ensuring uniform reaction in all areas of the reactor, and further enhancing the stability and uniformity of the denitrification effect.

[0038] Specifically, in this embodiment, the preparation method of the modified fly ash composite phosphorus removal agent in step four is as follows: fly ash and ferrous sulfate are mixed at a mass ratio of 10:1, calcined at 500-600℃ for 2-3 hours, and then pulverized to a particle size of less than 100 mesh. The mixture is then mixed evenly with zeolite powder at a mass ratio of 8:2. This method for preparing the modified fly ash composite phosphorus removal agent enhances the phosphorus adsorption performance of fly ash through calcination modification of fly ash and ferrous sulfate. Further enhancement of phosphorus removal capacity is achieved by combining it with zeolite powder. Using fly ash as the main raw material realizes the resource utilization of industrial waste, significantly reducing the preparation cost of phosphorus removal agents. Simultaneously, the optimization of the calcination and pulverization processes improves the dispersibility and reactivity of the agent, ensuring the stability of the phosphorus removal effect.

[0039] Specifically, in this embodiment, a pH online monitoring and adjustment device is installed in the phosphorus removal reaction tank in step four to control the pH of the reaction system to 7.0-7.5 in real time, with a stirring rate of 80-120 r / min. This scheme, by installing a pH online monitoring and adjustment device in the phosphorus removal reaction tank and controlling the stirring rate, can maintain a suitable pH environment required for the phosphorus removal reaction in real time, avoiding pH fluctuations from affecting the reaction efficiency between phosphorus and the reagent. A reasonable stirring rate ensures that the phosphorus removal reagent and wastewater are fully mixed, avoiding localized accumulation of the reagent that could lead to waste or incomplete reaction, thereby improving phosphorus removal efficiency, ensuring stable phosphorus removal results, and reducing reagent consumption.

[0040] Specifically, this embodiment also includes a sludge recirculation step, in which a portion of the sludge generated in the sedimentation tank is recirculated back to the short-cut nitrification reactor at a recirculation ratio of 30-50%, and the remaining sludge is treated in a sludge thickening tank. This newly added sludge recirculation step, by returning sedimentation tank sludge to the short-cut nitrification reactor, replenishes the functional microorganisms within the reactor, enhances the short-cut nitrification reaction capacity, and improves the stability of the nitrogen removal effect. The treatment of the remaining sludge in the thickening tank reduces the environmental pollution caused by direct sludge discharge, while also creating convenient conditions for subsequent sludge disposal, thus improving the environmental friendliness of the process and the overall operational stability.

[0041] Specifically, in this embodiment, the sludge thickening tank adopts gravity thickening, with a thickening time of 12-24 hours, and the moisture content of the thickened sludge is controlled at 85-90%. This scheme uses gravity thickening to treat excess sludge, eliminating the need for additional energy consumption and reducing energy consumption and costs in the sludge treatment process. A well-designed thickening process can effectively reduce the sludge moisture content and volume, facilitating subsequent sludge transportation, disposal, or resource utilization, thus improving the economy and practicality of the sludge treatment process.

[0042] Specifically, in this embodiment, an intermediate water tank is set up between the short-cut nitrification reactor and the anammox reactor. A water quality monitoring device is installed in the intermediate water tank to monitor the nitrite nitrogen and ammonia nitrogen concentrations in real time, ensuring that the molar ratio of nitrite nitrogen to ammonia nitrogen entering the anammox reactor is 1.0-1.3:1. This scheme, by setting up an intermediate water tank and equipping it with a water quality monitoring device between the short-cut nitrification and anammox reactors, allows for real-time monitoring of the substrate concentration ratio entering the anammox reactor. By adjusting the substrate molar ratio to ensure it matches the requirements of the anammox reaction, it avoids a decrease in reaction efficiency or failure due to substrate imbalance, thereby ensuring the efficient and stable operation of the anammox reaction and further improving the reliability and treatment effect of the entire nitrogen removal process.

[0043] Specifically, in this embodiment, the conversion process from ammonia nitrogen to nitrite nitrogen in the short-cut nitrification reactor is controlled by the following kinetic equation:

[0044]

[0045] in:

[0046] This refers to ammonia nitrogen concentration, expressed in mg / L.

[0047] [DO] represents the dissolved oxygen concentration, in mg / L.

[0048] [F] represents the effective biofilm attachment area of ​​the modified suspended packing material, in m² / m³.

[0049] k is the apparent reaction rate constant, with a value ranging from 0.12 to 0.18 mg / (L·h);

[0050] The dissolved oxygen half-saturation constant has a value ranging from 0.6 to 0.9 mg / L.

[0051] The value is the half-saturation constant of ammonia nitrogen, ranging from 8 to 12 mg / L;

[0052] It is the half-saturation constant of the packing adhesion effect, with a value range of 5–8 m² / m³.

[0053] This kinetic equation dynamically adjusts the hydraulic retention time and aeration intensity by monitoring ammonia nitrogen concentration, dissolved oxygen concentration, and packing material adhesion area in real time, thereby achieving a stable control of nitrification rate of not less than 85%.

[0054] Equation derivation process:

[0055] This equation is derived from the dynamics of the two-substrate-inhibited Monod equation, taking into account the following factors:

[0056] 1. Ammonia nitrogen is used as a substrate, and its conversion rate is affected by its own concentration (saturated type).

[0057] 2. Dissolved oxygen acts as an electron acceptor, and its concentration affects the efficiency of nitrite formation.

[0058] 3. The adhesion effect of packing material affects microbial retention and reactivity.

[0059] 4. To avoid conflicts across dimensions, all parameters are measured in units commonly used in wastewater treatment.

[0060] The derivation process is as follows:

[0061]

[0062] in:

[0063] This indicates the effect of dissolved oxygen on the reaction rate;

[0064] This indicates the effect of ammonia nitrogen concentration on the reaction rate;

[0065] This indicates the effect of filler adhesion on the reaction rate.

[0066] This equation incorporates the packing adhesion effect (F) as a kinetic variable into the short-range nitration model, making it suitable for specific process conditions involving modified suspended packing and low DO control.

[0067] Example:

[0068] Suppose at a certain moment:

[0069] =80mg / L;

[0070] [DO] = 1.2 mg / L;

[0071] [F] = 10 m² / m³;

[0072] k=0.15, =0.7, =10, =6;

[0073] Substitute into the equation:

[0074]

[0075] .

[0076] Based on this, the ammonia nitrogen removal rate within 4–6 hours can be estimated, and aeration and HRT can be adjusted in real time.

[0077] Parameter description table:

[0078]

[0079] Technical effects and working principle process:

[0080] Technical benefits: This equation enables quantitative and dynamic control of the short-cut nitrification process. Operating parameters can be adjusted in real time based on influent load, DO, and packing status to ensure a stable nitrite rate of ≥85%, thereby improving denitrification efficiency and system shock resistance.

[0081] Working principle and process:

[0082] 1. Real-time monitoring ;

[0083] 2. Substitute the values ​​into the equation to calculate the current reaction rate r;

[0084] 3. Calculate the required HRT based on the target ammonia nitrogen removal rate;

[0085] 4. Dynamically adjust the aeration system (control DO) or influent flow rate (control HRT);

[0086] 5. To achieve a stable molar ratio of nitrite to ammonia nitrogen of 1.0–1.3:1, providing ideal influent for anaerobic ammonia oxidation.

[0087] Working principle: This process is based on the synergistic treatment logic of pretreatment-short-cut nitrification-anaerobic ammonium oxidation-chemical assisted phosphorus removal. Through functional matching and parameter coordination of each unit, it achieves low-cost and high-efficiency nitrogen and phosphorus removal. First, the bar screen filter unit intercepts suspended impurities in the wastewater, preventing blockages in subsequent reactors. The equalization tank homogenizes water quality and quantity, providing stable influent conditions for subsequent biochemical reactions. In the short-cut nitrification reactor, modified suspended media provides an attachment carrier for microorganisms. Under low dissolved oxygen conditions, functional microorganisms convert ammonia nitrogen into nitrite nitrogen, eliminating the step of converting nitrite nitrogen to nitrate nitrogen in traditional nitrification and reducing energy consumption. In the anaerobic ammonia oxidation reactor, anaerobic ammonia oxidizing bacteria are immobilized on a carrier to retain functional bacterial communities. Under anaerobic conditions, they use nitrite nitrogen as an electron acceptor to oxidize ammonia nitrogen, achieving simultaneous nitrogen removal. Compared to traditional denitrification, no additional carbon source is required, further reducing costs. In the phosphorus removal reactor, modified fly ash composite phosphorus removal agent removes phosphorus pollutants through adsorption and chemical precipitation, utilizing industrial waste to prepare the agent for resource utilization. The water quality monitoring device in the intermediate tank regulates the substrate ratio in real time to ensure efficient anaerobic ammonia oxidation. The sludge return system replenishes functional microorganisms, improving process stability. The gravity thickener reduces sludge volume, lowering subsequent disposal costs. Through functional synergy, each unit forms a highly efficient treatment system that combines biochemical denitrification with low-cost chemical phosphorus removal, balancing treatment effectiveness and economy.

[0088] How to use:

[0089] 1. Pretreatment Start-up: The kitchen wastewater is introduced into the bar screen filter unit. After the bar screen intercepts suspended impurities, the wastewater enters the equalization tank. The stirring device in the equalization tank is turned on to make the water quality uniformly mixed. At the same time, the pH of the wastewater is adjusted to a suitable range and the water temperature is controlled to stabilize, thus completing the pretreatment stage.

[0090] 2. Short-cut nitrification operation: The pretreated wastewater is pumped into the short-cut nitrification reactor to ensure that the modified suspended packing material in the reactor is in a suspended state. The dissolved oxygen concentration is controlled by adjusting the aeration system and maintaining the set hydraulic retention time to convert ammonia nitrogen in the wastewater into nitrite nitrogen. The nitrite conversion rate is monitored regularly.

[0091] 3. Anaerobic ammonia oxidation operation: The effluent from the short-cut nitrification reactor enters the intermediate water tank. The concentrations of nitrite nitrogen and ammonia nitrogen are monitored by a water quality monitoring device to ensure that the ratio is appropriate before being introduced into the anaerobic ammonia oxidation reactor. The pH and hydraulic retention time in the reactor are controlled to ensure that the wastewater is in full contact with the immobilized carrier of anaerobic ammonia oxidizing bacteria under anaerobic conditions, so as to achieve simultaneous removal of ammonia nitrogen and nitrite nitrogen.

[0092] 4. Chemical-assisted phosphorus removal: The effluent from the anaerobic ammonia oxidation reactor enters the phosphorus removal reaction tank, where a modified fly ash composite phosphorus removal agent is added in proportion. The stirring device is turned on to ensure that the agent and the wastewater are fully mixed and the reaction time is maintained. After the reaction is completed, the wastewater enters the sedimentation tank to achieve solid-liquid separation. The effluent from the sedimentation tank is the compliant effluent.

[0093] 5. Sludge treatment: Activate the sludge return system to return part of the sludge generated in the sedimentation tank to the short-cut nitrification reactor, and discharge the remaining sludge into the gravity thickener; reduce the sludge moisture content through gravity thickening, and then carry out subsequent treatment of the thickened sludge.

[0094] 6. Operation and Control: Real-time monitoring of influent and effluent water quality in each unit; adjustment of substrate ratio through water quality monitoring device in intermediate water tank; and adjustment of reaction pH through online pH monitoring and adjustment device in phosphorus removal reactor to ensure stable parameters in each unit and guarantee treatment effect.

[0095] In summary, this low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater has the following advantages:

[0096] This process achieves efficient and stable treatment of nitrogen and phosphorus removal from kitchen wastewater and cost control through a combined design of pretreatment, short-cut nitrification, anaerobic ammonia oxidation, and chemical-assisted phosphorus removal, along with sludge recirculation and intermediate water quality control. The pretreatment unit effectively intercepts impurities and homogenizes water quality, preventing blockages and water quality shocks in subsequent reaction units, thus laying the foundation for stable operation of the overall process. The coupling of the short-cut nitrification reactor and the anaerobic ammonia oxidation reactor eliminates some steps in traditional nitrification-denitrification processes, reducing aeration energy consumption and carbon source addition requirements. Simultaneously, the selection of modified suspended packing and immobilized carriers for anaerobic ammonia oxidation bacteria enhances the retention capacity and reaction efficiency of functional microorganisms, ensuring stable nitrogen removal. The application of modified fly ash composite phosphorus removal agent realizes the resource utilization of industrial waste, significantly reducing costs compared to conventional chemical phosphorus removal agents while improving the stability of phosphorus removal. The design of the water quality monitoring device and sludge return system in the intermediate pool further optimizes reaction conditions and enhances the process's resistance to water quality fluctuations. The application of the gravity thickener reduces energy consumption and costs for sludge disposal.

[0097] Overall, the process, through the synergistic function of each unit, not only achieves efficient removal of nitrogen and phosphorus pollutants, adapting to the treatment needs of kitchen wastewater with large fluctuations in water quality and high nitrogen and phosphorus concentrations, but also significantly reduces treatment costs through process simplification, selection of low-cost reagents, and energy conservation. At the same time, sludge return and concentration treatment improve the environmental friendliness and operational stability of the process, avoid secondary pollution, and have good economic efficiency and practicality, making it suitable for large-scale promotion and application.

[0098] In addition, this embodiment also provides the following three examples:

[0099] Example 1: Small-scale laboratory test for nitrogen and phosphorus removal from kitchen wastewater

[0100] I. Technical Solution

[0101] This example is for a small-scale laboratory wastewater treatment facility with a daily processing capacity of 50L, and the specific steps are as follows:

[0102] 1. Pretreatment: The kitchen wastewater is introduced into the bar screen filter unit, and a bar screen with a pore size of 2mm is used to intercept food residue, fiber and other suspended impurities. After filtration, the wastewater enters the equalization tank, the stirring device in the tank is turned on, the stirring rate is controlled at 80r / min, the pH of the wastewater is adjusted to 7.2-7.6, and the water temperature is maintained at 25-28℃ to achieve equalization of water quality and quantity.

[0103] 2. Short-cut nitrification: The effluent from the equalization tank is pumped into the short-cut nitrification reactor. Iron-modified polyurethane foam suspension packing is added to the reactor, with a packing filling rate of 35%. The sludge concentration in the reactor is controlled at about 4000 mg / L. The dissolved oxygen concentration is adjusted to 1.0-1.2 mg / L through the aeration system, and the hydraulic retention time is set to 5 hours.

[0104] 3. Anaerobic ammonia oxidation: The effluent from the short-cut nitrification reactor is introduced into the anaerobic ammonia oxidation reactor. The reactor is filled with sodium alginate-polyvinyl alcohol composite anaerobic ammonia oxidizing bacteria immobilization carrier with a particle size of 4 mm. The inoculum amount of anaerobic ammonia oxidizing bacteria is 6 g / L. The pH in the reactor is controlled at 7.8-8.0, the hydraulic retention time is 10 h, and an anaerobic environment (dissolved oxygen concentration <0.2 mg / L) is maintained.

[0105] 4. Chemical-assisted phosphorus removal: The effluent from the anaerobic ammonia oxidation reactor enters the phosphorus removal reaction tank, where a modified fly ash composite phosphorus removal agent is added (preparation method: fly ash and ferrous sulfate are mixed at a mass ratio of 10:1, calcined at 550℃ for 2.5 hours, then pulverized to 80 mesh, and then mixed evenly with zeolite powder at a mass ratio of 8:2). The dosage of the agent is 20 times the mass of total phosphorus in the wastewater. The stirring device is turned on, and the stirring speed is controlled at 100 r / min. After reacting for 25 minutes, the mixture enters the sedimentation tank and is allowed to stand for 30 minutes to achieve solid-liquid separation. The effluent from the sedimentation tank is the treated effluent.

[0106] II. Working Principle

[0107] The bar screen filter intercepts suspended impurities, preventing clogging of the packing material in subsequent reactors and laying the foundation for stable reactions. The equalization tank homogenizes water quality through stirring, eliminating the impact of water quality and quantity fluctuations on subsequent biochemical reactions. In the short-cut nitrification reactor, modified suspended packing provides stable attachment sites for nitrite-oxidizing bacteria. The low dissolved oxygen environment selectively enriches nitrite-oxidizing bacteria, converting ammonia nitrogen in wastewater into nitrite nitrogen, eliminating the step of nitrite nitrogen to nitrate nitrogen conversion in traditional nitrification and reducing aeration energy consumption. In the anaerobic ammonia oxidation reactor, immobilized carriers retain anaerobic ammonia-oxidizing bacteria, preventing the loss of functional bacteria. Under anaerobic conditions, anaerobic ammonia-oxidizing bacteria use nitrite nitrogen as an electron acceptor to oxidize ammonia nitrogen, achieving simultaneous nitrogen removal without the need for additional carbon sources. In the phosphorus removal reactor, modified fly ash composite phosphorus removal agent captures phosphorus pollutants through surface adsorption and chemical precipitation, achieving efficient phosphorus removal. The sedimentation tank completes solid-liquid separation, ensuring clear effluent. All units work together to form a complete nitrogen and phosphorus removal system, balancing efficiency and cost control.

[0108] III. Experimental Data

[0109] Influent water quality: COD 1800-2200mg / L, ammonia nitrogen 350-420mg / L, total phosphorus 45-55mg / L, pH 6.5-7.8;

[0110] Effluent water quality: COD 180-220 mg / L, ammonia nitrogen 15-25 mg / L, total phosphorus 0.8-1.2 mg / L, pH 7.0-7.5;

[0111] Key reaction efficiencies: Short-cut nitrification nitrification rate 90-92%, anaerobic ammonia oxidation denitrification efficiency 88-90%, phosphorus removal efficiency 97-98%.

[0112] IV. Technical Effects

[0113] This example demonstrates the efficient and simultaneous removal of nitrogen and phosphorus pollutants from small-scale kitchen wastewater treatment through a compact process design and precise parameter control, ensuring stable effluent quality. The selection of modified suspended media and anaerobic ammonia-oxidizing bacteria immobilization carriers enhances the retention capacity of functional microorganisms and strengthens the stability of biochemical denitrification. The application of modified fly ash composite phosphorus removal agent realizes the resource utilization of industrial waste, significantly reducing phosphorus removal costs. The overall process is flexible in operation, requires minimal space, and eliminates the need for complex equipment, making it suitable for laboratory research or emergency wastewater treatment needs at small kitchen waste treatment sites, providing a reliable experimental basis for the large-scale application of the process.

[0114] Example 2: Pilot-scale nitrogen and phosphorus removal test of kitchen wastewater

[0115] I. Technical Solution

[0116] This example focuses on a pilot-scale wastewater treatment plant with a daily processing capacity of 5 m³, which includes the addition of an intermediate water tank and water quality monitoring device, as well as an online pH monitoring and adjustment device for the phosphorus removal reaction tank. The specific steps are as follows:

[0117] 1. Pretreatment: The kitchen wastewater is filtered through a bar screen filter unit (3mm mesh size) and then enters the equalization tank (effective volume 12m³). The stirring device is turned on (stirring speed 90r / min), the pH is adjusted to 7.0-7.8, and the water temperature is controlled at 24-30℃.

[0118] 2. Short-cut nitrification: The effluent from the equalization tank is introduced into the short-cut nitrification reactor (effective volume 8m³), and iron-modified polyurethane foam suspension packing is added (filling rate 38%). The sludge concentration is controlled at 3800mg / L, the dissolved oxygen concentration is 1.1-1.4mg / L, and the hydraulic retention time is 5.5h.

[0119] 3. Intermediate water quality control: The effluent from the short-cut nitrification reactor enters the intermediate water tank (effective volume 2m³). The concentrations of nitrite nitrogen and ammonia nitrogen are monitored in real time by a water quality monitoring device to ensure that the molar ratio of the two is 1.1-1.2:1. If the ratio is unbalanced, the aeration rate of the short-cut nitrification reactor is adjusted for fine adjustment.

[0120] 4. Anaerobic ammonia oxidation: The effluent from the intermediate water tank is introduced into an upflow anaerobic ammonia oxidation reactor (effective volume 15m³). 3 The bottom is equipped with a water distribution device (water distribution rate 0.8m / h), and the reactor is filled with sodium alginate-polyvinyl alcohol composite anaerobic ammonia-oxidizing bacteria immobilization carrier (particle size 3-5mm, inoculum amount 7g / L). The pH is controlled at 7.6-8.2, the hydraulic retention time is 11h, and the anaerobic environment is maintained.

[0121] 5. Chemical-assisted phosphorus removal: The effluent from the anaerobic ammonia oxidation reactor enters the phosphorus removal reaction tank (effective volume 6 m³), ​​and the same modified fly ash composite phosphorus removal agent as in Example 1 is added, with the agent dosage being 22 times the total phosphorus mass; the stirring device is turned on (stirring speed 110 r / min), and the pH of the reaction system is controlled in real time to 7.2-7.4 through the pH online monitoring and adjustment device. After reacting for 28 min, the effluent enters the sedimentation tank (effective volume 10 m³), ​​and the effluent is discharged after solid-liquid separation.

[0122] II. Working Principle

[0123] This example, based on the core process, utilizes an upflow anaerobic ammonium oxidation reactor and a bottom water distribution device to achieve uniform water flow distribution, avoid local short-circuiting, enhance the contact between wastewater and the immobilized carrier, and improve mass transfer efficiency and bacterial retention. The addition of an intermediate tank and water quality monitoring device enables precise integration of short-cut nitrification and anaerobic ammonium oxidation reactions, ensuring the substrate ratio matches the metabolic needs of anaerobic ammonium oxidizing bacteria and preventing a decrease in reaction efficiency due to substrate imbalance. The application of an online pH monitoring and adjustment device in the phosphorus removal reactor maintains a suitable acid-base environment for the phosphorus removal reaction in real time, preventing pH fluctuations from affecting the activity of the reagents and ensuring stable phosphorus removal results. Through functional synergy and precise control, each unit forms a highly efficient treatment system suitable for pilot-scale operation, balancing treatment efficiency, operational stability, and cost control requirements.

[0124] III. Experimental Data

[0125] Influent water quality: COD 2000-2500mg / L, ammonia nitrogen 380-450mg / L, total phosphorus 50-60mg / L, pH 6.3-8.0;

[0126] Effluent water quality: COD 190-230 mg / L, ammonia nitrogen 12-20 mg / L, total phosphorus 0.6-1.0 mg / L, pH 7.1-7.6;

[0127] Key reaction efficiencies: Short-cut nitrification nitrification rate 89-93%, anaerobic ammonia oxidation nitrogen removal efficiency 89-92%, phosphorus removal efficiency 98-99%; Operating energy consumption: 0.8-1.0 kWh / m³ wastewater; Chemical cost: 0.3-0.4 yuan / m³ wastewater.

[0128] IV. Technical Effects

[0129] This example further enhances the operational stability and shock resistance of the process by adding intermediate water quality control and online pH adjustment devices, adapting to small fluctuations in water quality and quantity at the pilot-scale level. The design of the upflow anaerobic ammonia oxidation reactor strengthens the uniformity of nitrogen removal and avoids the problem of incomplete local reactions; precise pH control in the phosphorus removal reactor improves reagent reaction efficiency and reduces reagent waste. The overall process achieves efficient and stable removal of nitrogen and phosphorus at the pilot-scale level, significantly reducing operating energy consumption and reagent costs. The process is highly adaptable, providing key parameter support and technical verification for subsequent practical engineering applications. Furthermore, the process is easy to operate, requiring no complex operation and maintenance management, making it easy to extend to wastewater treatment in small and medium-sized food waste treatment centers.

[0130] Example 3: Application of nitrogen and phosphorus removal in actual engineering projects for kitchen wastewater treatment

[0131] I. Technical Solution

[0132] This example is for a real-scale project treating kitchen wastewater with a daily processing capacity of 500 m³. It includes the addition of a sludge return system and a gravity thickener. The specific steps are as follows:

[0133] 1. Pretreatment: Wastewater from kitchen waste is filtered through a bar screen filter unit (bar screen aperture 1.5mm) and then enters the equalization tank (effective volume 150m³). The stirring device has a stirring rate of 70r / min, and the pH is adjusted to 6.8-7.6 and the water temperature is 26-32℃.

[0134] 2. Short-cut nitrification: The effluent from the equalization tank is introduced into the short-cut nitrification reactor (effective volume 80m³), and iron-modified polyurethane foam suspension packing is added (filling rate 32%). The sludge concentration is controlled at 3500mg / L, the dissolved oxygen concentration is 0.9-1.3mg / L, and the hydraulic retention time is 4.8h.

[0135] 3. Intermediate water quality control: The effluent enters the intermediate water tank (effective volume 30m³), and the water quality monitoring device controls the molar ratio of nitrite nitrogen to ammonia nitrogen to be 1.0-1.3:1.

[0136] 4. Anaerobic ammonia oxidation: An upflow anaerobic ammonia oxidation reactor (effective volume 180m³) is introduced, with a water distribution rate of 0.7m / h at the bottom, filled with an immobilized anaerobic ammonia oxidizing bacteria carrier (particle size 4-5mm, inoculum amount 8g / L), pH 7.5-8.3, and hydraulic retention time 9.5h.

[0137] 5. Chemical-assisted phosphorus removal: The phosphorus is introduced into the phosphorus removal reaction tank (effective volume 60m³), and modified fly ash composite phosphorus removal agent (preparation method: fly ash and ferrous sulfate 10:1, calcined at 580℃ for 2h, pulverized to 100 mesh and mixed with zeolite powder 8:2) is added. The amount added is 24 times the total phosphorus mass. The stirring rate is 100r / min, the pH is adjusted online to 7.1-7.5, and after reacting for 26min, it is introduced into the sedimentation tank (effective volume 120m³).

[0138] 6. Sludge disposal: Turn on the sludge return system and return the sludge from the sedimentation tank to the short-cut nitrification reactor at a return ratio of 40%; the remaining sludge is discharged into the gravity thickener (effective volume 50m³) and gravity thickened for 20h. The thickened sludge is then transported off-site for disposal.

[0139] II. Working Principle

[0140] This example addresses the significant fluctuations in water quality and quantity characteristic of large-scale engineering projects. A sludge return system recirculates sludge from the sedimentation tank back to the short-cut nitrification reactor, replenishing lost functional microorganisms, maintaining stable sludge concentration, enhancing short-cut nitrification capacity, and improving the process's resilience to water quality fluctuations. The gravity thickener utilizes a low-cost gravity thickening method to reduce excess sludge volume, lowering sludge transportation and subsequent disposal costs. The uniform water distribution design and precise control of the intermediate water tank in the upflow anaerobic ammonia oxidation reactor ensure uniform and efficient denitrification under large-scale operation. The large-scale application of modified fly ash composite phosphorus removal agent enables the batch conversion of industrial waste into resources, further controlling treatment costs. Through process synergy, precise control, and sludge resource utilization, each unit forms a stable treatment system suitable for large-scale kitchen wastewater treatment, balancing treatment effectiveness, operational stability, and economic efficiency.

[0141] III. Experimental Data

[0142] Influent water quality: COD 1900-2600mg / L, ammonia nitrogen 360-480mg / L, total phosphorus 48-62mg / L, pH 6.2-8.1;

[0143] Effluent water quality: COD 185-240 mg / L, ammonia nitrogen 10-18 mg / L, total phosphorus 0.5-0.9 mg / L, pH 7.0-7.7;

[0144] Key reaction efficiencies: Short-cut nitrification nitrification rate 88-92%, anaerobic ammonia oxidation nitrogen removal efficiency 90-93%, phosphorus removal efficiency 98-99%; Operating energy consumption: 0.7-0.9 kWh / m³ wastewater; Chemical cost: 0.28-0.38 yuan / m³ 3 Wastewater; sludge production: 0.3-0.4 kg / m³ wastewater.

[0145] IV. Technical Effects

[0146] This example demonstrates efficient and stable treatment of large-scale kitchen wastewater through the integration of large-scale process design with auxiliary systems such as sludge return and gravity thickening, ensuring consistently high effluent quality. The sludge return system enhances the retention and replenishment of functional microorganisms, significantly improving the process's adaptability to fluctuations in water quality and quantity in actual engineering projects. The low-cost sludge disposal method of the gravity thickening tank reduces energy consumption and costs for subsequent sludge treatment and avoids secondary pollution. The large-scale application of modified suspended media and immobilized carriers ensures efficient and stable biochemical reactions. The batch use of modified fly ash composite phosphorus removal agent achieves synergistic optimization of cost control and pollutant removal. The overall process is simplified and easy to operate and maintain, maintaining low energy consumption and low cost advantages even in large-scale applications. It is well-suited to the large-scale wastewater treatment needs of the kitchen wastewater treatment industry and possesses significant promotional value and economic benefits.

[0147] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater, characterized in that, Includes the following steps: Step 1, pretreatment: introduce kitchen wastewater into the bar screen filter unit to remove suspended impurities, and then enter the equalization tank for water quality and quantity adjustment, controlling the pH of the effluent from the equalization tank to 6.8-7.8 and the water temperature to 22-32℃; Step 2, short-cut nitrification: The effluent from the equalization tank is introduced into the short-cut nitrification reactor, and modified suspended packing is added to the reactor. The dissolved oxygen concentration in the reactor is controlled at 0.8-1.5 mg / L, and the hydraulic retention time is 4-6 h to achieve the conversion of ammonia nitrogen to nitrite nitrogen, with a nitrite conversion rate of not less than 85%. Step 3, anaerobic ammonia oxidation: The effluent from the short-cut nitrification reactor is introduced into the anaerobic ammonia oxidation reactor. The reactor is filled with an immobilized carrier of anaerobic ammonia oxidizing bacteria. The pH in the reactor is controlled at 7.5-8.3 and the hydraulic retention time is 8-12 hours. Under anaerobic conditions, ammonia nitrogen and nitrite nitrogen are removed simultaneously. Step four, chemical-assisted phosphorus removal: introduce the effluent from the anaerobic ammonia oxidation reactor into the phosphorus removal reaction tank, add modified fly ash composite phosphorus removal agent into the tank, control the agent dosage to be 15-25 times the total phosphorus mass in the wastewater, stir and react for 20-30 minutes, then enter the sedimentation tank for solid-liquid separation, the effluent from the sedimentation tank is the qualified effluent.

2. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, The grid filter unit described in step one has a grid aperture of 1-3mm, and a stirring device is installed in the regulating tank with a stirring rate of 60-100r / min.

3. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, The modified suspended packing material mentioned in step two is made of polyurethane foam modified with iron ions. The packing material filling rate is 30-40% of the effective volume of the reactor, and the sludge concentration in the reactor is controlled at 3000-5000 mg / L.

4. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, The anaerobic ammonia oxidizing bacteria immobilization carrier mentioned in step three is a sodium alginate-polyvinyl alcohol composite carrier with a particle size of 3-5 mm and an inoculum amount of anaerobic ammonia oxidizing bacteria of 5-8 g / L.

5. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, The anaerobic ammonia oxidation reactor described in step three is an upflow reactor with a water distribution device at the bottom of the reactor. The water distribution rate is 0.5-1.0 m / h to ensure uniform water flow.

6. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, The preparation method of the modified fly ash composite phosphorus removal agent in step four is as follows: fly ash and ferrous sulfate are mixed at a mass ratio of 10:1, calcined at 500-600℃ for 2-3 hours, and then pulverized until the particle size is less than 100 mesh. Then, it is mixed evenly with zeolite powder at a mass ratio of 8:

2.

7. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, In step four, a pH online monitoring and adjustment device is installed in the phosphorus removal reaction tank to control the pH of the reaction system to 7.0-7.5 in real time, and the stirring rate to 80-120 r / min.

8. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 1, characterized in that, It also includes a sludge return step, in which part of the sludge produced in the sedimentation tank is returned to the short-cut nitrification reactor at a return ratio of 30-50%, and the remaining sludge is sent to the sludge thickening tank for treatment.

9. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to claim 8, characterized in that, The sludge thickening tank adopts gravity thickening method, with a thickening time of 12-24 hours, and the moisture content of the thickened sludge is controlled at 85-90%.

10. The low-cost nitrogen and phosphorus removal treatment process for kitchen wastewater according to any one of claims 1-9, characterized in that, An intermediate water tank is set between the short-cut nitrification reactor and the anaerobic ammonia oxidation reactor. A water quality monitoring device is installed in the intermediate water tank to monitor the nitrite nitrogen concentration and ammonia nitrogen concentration in real time, ensuring that the molar ratio of nitrite nitrogen to ammonia nitrogen entering the anaerobic ammonia oxidation reactor is 1.0-1.3:1.

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