A low-carbon synergistic treatment system and method for efficient denitrification and dephosphorization of livestock and poultry breeding wastewater

Abstract

This invention belongs to the field of wastewater treatment technology and provides a low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater. This system includes: a pretreatment device that removes floating matter from the wastewater using physical methods, and after coagulation with a coagulant, produces primary wastewater; a biogas recovery and utilization device where the primary wastewater undergoes anaerobic reaction to produce biogas and secondary wastewater; an aerobic granular sludge + biofilm device where the secondary wastewater undergoes nitrogen and phosphorus removal and antibiotic removal through the action of aerobic granular sludge and biofilm, producing tertiary wastewater; and a Chlorella treatment device where Chlorella further removes residual nitrogen and phosphorus from the tertiary wastewater. The low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater provided by this invention does not require the addition of chemical agents for phosphorus removal, saving on reagent costs and being environmentally friendly. It also features no need for additional carbon sources, small footprint, and low operating costs.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, specifically relating to a low-carbon synergistic treatment system and method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater. Background Technology

[0002] With economic and population growth, the demand for livestock and poultry products is increasing. While large-scale livestock and poultry farming meets this demand, it also generates a large amount of livestock and poultry wastewater. Data shows that a pig farm with approximately 100,000 pigs can generate about 260 tons of wastewater per day. This wastewater has high levels of ammonia nitrogen and phosphorus and contains a large number of pathogens. If discharged directly into the surrounding environment without treatment, it will cause serious environmental pollution, such as eutrophication of water bodies and impacting the survival of nearby humans. Livestock and poultry wastewater is currently the third largest source of pollution after industrial and domestic wastewater. During the livestock and poultry farming process, antibiotics such as tetracycline are often injected into livestock and poultry to prevent diseases. The utilization rate of antibiotics by livestock and poultry is less than 40%, and the remainder enters the livestock and poultry wastewater through urine and feces. Without proper treatment, this can cause antibiotic pollution, ultimately impacting human health and the safety of the entire ecosystem. Currently, the livestock and poultry farming industry in the Yangtze and Yellow River basins discharges large amounts of manure and wastewater, with high levels of organic matter and nitrogen and phosphorus pollution. Existing treatment and disposal processes suffer from drawbacks such as low resource and energy conversion efficiency, high disposal costs, high greenhouse gas emissions, and high ecological and environmental risks. Conventional wastewater treatment processes are difficult to use for livestock and poultry farm wastewater containing high concentrations of ammonia nitrogen, phosphorus, COD, and antibiotics, incur high operation and management costs, and cannot effectively address issues such as pollutant residues.

[0003] Livestock and poultry farming has relatively high costs and low profits. It is extremely important to invent a livestock and poultry farming wastewater treatment process with low operating and management costs. At the same time, the livestock and poultry farming wastewater treatment process should ideally be low-carbon and environmentally friendly, and achieve resource and energy recovery. Therefore, there is an urgent need to carry out research on new technologies for the low-carbon and low-cost treatment of livestock and poultry farming wastewater on a large scale. Summary of the Invention

[0004] To address the problems of low resource and energy conversion efficiency, high treatment costs, high greenhouse gas emissions, high ecological and environmental risks in existing livestock and poultry breeding wastewater treatment processes, as well as the difficulty in treating livestock and poultry breeding wastewater containing high concentrations of ammonia nitrogen, phosphorus, COD, and antibiotics, high operation and management costs, and the inability to effectively solve pollutant residues, this invention provides a low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater.

[0005] This low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry farming wastewater includes:

[0006] A pretreatment device that removes floating matter from wastewater using physical methods, and then coagulates it with a coagulant to produce primary wastewater.

[0007] A biogas recovery and utilization device, wherein the primary wastewater undergoes anaerobic reaction in the biogas recovery device to produce biogas and secondary wastewater;

[0008] The aerobic granular sludge + biofilm device, in which the secondary wastewater undergoes denitrification, dephosphorization and antibiotic removal through the action of aerobic granular sludge and biofilm, producing tertiary wastewater;

[0009] The Chlorella treatment device further removes residual nitrogen and phosphorus from the tertiary wastewater using Chlorella.

[0010] Furthermore, the pretreatment device includes a bar screen, a grit chamber, a multi-stage drum screen, a collection tank, a flocculation sedimentation tank, and a press. Wastewater passes through the bar screen to intercept floating debris. After initial settling in the grit chamber, solids are separated from the solids by the multi-stage drum screen. The solids are then pressed by the press and used for fermentation. The liquid is added to a coagulant and flocculated in the flocculation sedimentation tank to produce primary wastewater.

[0011] Furthermore, the biogas recovery and utilization device includes a UASB reactor, a methane collection and purification component, a gas boiler, a heat exchanger, and a three-phase separator. The primary wastewater undergoes anaerobic reaction in the UASB reactor to produce biogas and secondary wastewater. After separation by the three-phase separator, the gas generates heat through combustion in the gas boiler, and the heat is transferred to the UASB reactor in the heat exchanger.

[0012] Furthermore, the biogas recovery and utilization device also includes a gas flow meter, a gas pump, a three-phase separator, a temperature detector, and a stirrer.

[0013] Furthermore, the aerobic granular sludge + biofilm device includes an aerobic granular sludge + biofilm reactor, a blower, an aeration pipe, a hydrocyclone, a self-circulating pump, a three-phase separator, and a biofilm. The secondary wastewater enters the lower part of the aerobic granular sludge + biofilm reactor, where the blower aerates the water through the aeration pipe, and the hydrocyclone distributes the water evenly. Then, the secondary wastewater enters the biofilm treatment section at the top of the aerobic granular sludge + biofilm reactor, generating tertiary wastewater, which can be self-circulated back by the self-circulating pump.

[0014] Furthermore, the Chlorella treatment device 4 includes a Chlorella reactor, a water pump, and a solar panel. The tertiary wastewater is pumped into the Chlorella reactor by the water pump, and the Chlorella reactor is heated by the solar panel.

[0015] One objective of this invention is to provide a low-carbon synergistic treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater.

[0016] The low-carbon synergistic treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater includes the following steps:

[0017] S1: Use the pretreatment device described in any of the above to remove floating matter from livestock and poultry breeding wastewater, and separate manure and primary wastewater, wherein the primary wastewater is anaerobicly reacted in a biogas recovery and utilization device to produce biogas and secondary wastewater.

[0018] S2: The secondary wastewater is denitrified, dephosphorized and removed from antibiotics by ammonia-oxidizing bacteria and denitrifying bacteria, and biofilm biological action in the continuous flow aerobic granular sludge + biofilm reactor as described in any of the above items, to produce tertiary wastewater;

[0019] S3: Further absorb the residual nitrogen and phosphorus in the tertiary wastewater using a Chlorella reactor as described in any of the above items.

[0020] Further, S1 includes: the primary wastewater undergoes anaerobic reaction at the bottom of the UASB reactor to produce biogas; the agitator drives the agitator blades to rotate to ensure uniform water distribution; the biogas produced is discharged through the three-phase separator and enters the methane collection and purification assembly; the methane is pumped into the gas boiler through the gas flow meter and the gas pump; the heat generated by the combustion of methane in the gas boiler is transferred to the UASB reactor 21 through the heat exchanger.

[0021] Further, S2 includes: the secondary wastewater enters the lower part of reactor B via a water pump, the blower aerates the water through the aeration pipe, the hydrocyclone distributes the water evenly, and then the secondary wastewater enters the biofilm treatment section.

[0022] This invention proposes a method and apparatus for "pretreatment of livestock and poultry breeding wastewater—biogas production and organic matter recovery via UASB—continuous flow aerobic granular sludge + biofilm for efficient nitrogen, phosphorus removal and antibiotic removal—deep nitrogen and phosphorus removal via Chlorella". This method eliminates the need for chemical agents for phosphorus removal, saving on reagent costs and being environmentally friendly. Compared to traditional wastewater treatment processes, the continuous flow aerobic granular sludge reactor is simpler, requires no additional carbon source, occupies less space, and has lower operating costs. It has significant application value in treating high-ammonia nitrogen wastewater such as livestock and poultry breeding wastewater. Deep nitrogen and phosphorus removal is achieved using Chlorella, which synergistically purifies the wastewater while growing. Organic matter in the wastewater is recovered; the recovered Chlorella can be used as an additive in livestock and poultry feed. The treated wastewater is recycled, realizing resource utilization of wastewater. Compared to traditional wastewater treatment processes, this method reduces treatment costs and achieves resource utilization of wastewater, meeting the current national requirements for synergistic efficiency improvement in wastewater treatment. Attached Figure Description

[0023] Figure 1 A structural diagram of a low-carbon co-treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater;

[0024] Figure 2 This is a structural diagram of a biogas recovery and utilization device;

[0025] Figure 3 This is a structural diagram of an aerobic granular sludge + biofilm device;

[0026] Figure 4 This is a structural diagram of a Chlorella treatment device;

[0027] Figure 5 Flowchart of a low-carbon co-treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but this should not be construed as limiting the scope of the present invention.

[0029] According to the Technical Specification for Pollution Control Engineering of Livestock and Poultry Breeding Industry (HJ 497—2009), the main water quality characteristics of livestock and poultry breeding wastewater are shown in the table below.

[0030] Table 1. Water quality characteristics of livestock and poultry breeding wastewater

[0031]

[0032]

[0033] Livestock and poultry farming wastewater, a typical type of high-ammonia-nitrogen wastewater, is characterized by large volume, poor water quality, high chemical oxygen demand (COD), and high concentrations of ammonia nitrogen and total phosphorus, as well as the presence of antibiotic pollutants. Conventional single wastewater treatment processes are challenging to treat this type of wastewater and cannot effectively remove the high concentrations of nitrogen and phosphorus from livestock and poultry farming wastewater. Therefore, this invention proposes a method and apparatus consisting of "pretreatment of livestock and poultry breeding wastewater—UASB biogas production and organic matter recovery—continuous flow aerobic granular sludge + biofilm for efficient nitrogen and phosphorus removal and antibiotic removal—Chlorella deep nitrogen and phosphorus removal." This method eliminates the need for chemical agents to remove phosphorus, saving on reagent costs and being environmentally friendly. Compared to traditional wastewater treatment processes, the continuous flow aerobic granular sludge reactor is simpler, requires no additional carbon source, occupies less space, and has lower operating costs. It has significant application value in treating high-ammonia nitrogen wastewater such as livestock and poultry breeding wastewater. Chlorella is used for deep nitrogen and phosphorus removal, synergistically purifying the livestock and poultry breeding wastewater while growing. Organic matter in the wastewater is recovered; the recovered Chlorella can be used as an additive in livestock and poultry feed. The treated wastewater is recycled, realizing resource utilization of wastewater. Compared to traditional wastewater treatment processes, this method reduces treatment costs and achieves resource utilization of wastewater, meeting the current national requirements for synergistic efficiency improvement in wastewater treatment.

[0034] Example 1

[0035] This invention provides a low-carbon synergistic treatment system 100 for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater. (See reference...) Figure 1 The low-carbon co-treatment system 100 for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater includes a pretreatment unit 1, a biogas recovery and utilization unit 2, an aerobic granular sludge + biofilm unit 3, and a Chlorella treatment unit 4. The pretreatment unit 1 removes floating matter from the wastewater using physical methods. After coagulation with a coagulant, the wastewater is classified as primary wastewater and pumped into the biogas recovery unit 2. In the biogas recovery unit 2, the primary wastewater undergoes an anaerobic reaction, producing biogas and secondary wastewater. The biogas can generate heat through combustion to maintain the anaerobic reaction temperature. The secondary wastewater enters the aerobic granular sludge + biofilm unit 3, where it undergoes nitrogen and phosphorus removal and antibiotic removal, resulting in tertiary wastewater. The Chlorella treatment unit 4 utilizes algae to further absorb residual nitrogen and phosphorus in the tertiary wastewater. The effluent concentrations of the treated livestock and poultry breeding wastewater are all below the limits specified in the "Emission Standard of Pollutants for Livestock and Poultry Breeding Industry" (GB / T18596-2001).

[0036] Pretreatment unit 1 includes a screen, a grit chamber, a multi-stage drum screen, a collection tank, a flocculation sedimentation tank, and a press. The screen traps large floating objects carried in the livestock and poultry breeding wastewater. After initial settling in the grit chamber, the wastewater passes through the multi-stage drum screen to achieve solid-liquid separation, removing floating objects such as manure. The wastewater then enters the flocculation sedimentation tank, where PAC / PAM is added to enhance coagulation. Finally, it is pumped into biogas recovery and utilization unit 2. The screened-out manure is dewatered by the press and then fermented into organic fertilizer. The wastewater treated by pretreatment unit 1 is classified as Class I wastewater.

[0037] See Figure 2 The biogas recovery and utilization device 2 includes a UASB reactor (reactor A) 21, a methane collection and purification assembly 22, a gas flow meter 23, a gas pump 24, a gas boiler 25, a heat exchanger 26, a three-phase separator 27, a temperature detector 28, and a stirrer 29. Reactor A 21 includes an inlet 211 and an outlet 212. The stirrer 29 includes stirring blades 291. The stirring blades 291 are located at the bottom of reactor A 21 through the inlet 211. The three-phase separator 27 is located at the top of reactor A. Primary wastewater undergoes anaerobic reaction at the bottom of the UASB reactor (reactor A) to produce biogas. Agitator 29 drives the stirring blades 291 to rotate, ensuring even water distribution. The generated biogas is discharged through three-phase separator 27 and then enters methane collection and purification component 22 (methane yield ≥95%). The methane is then pumped into gas boiler 25 via gas flow meter 23 and gas pump 24. The heat generated by methane combustion in the gas boiler is transferred to UASB reactor 21 via heat exchanger 26. Temperature detector 28 monitors the internal temperature of UASB reactor 21, maintaining it at approximately 30 degrees Celsius (organic carbon removal rate ≥95%). The secondary wastewater obtained after treatment by UASB reactor 21 is pumped into aerobic granular sludge + biofilm device 3.

[0038] See Figure 3The aerobic granular sludge + biofilm device 3 includes an aerobic granular sludge + biofilm reactor (reactor B) 31, a water pump 32, a blower 33, an aeration pipe 34, a hydrocyclone 35, a self-circulating pump 36, a three-phase separator 37, and a biofilm 38. The aerobic granular sludge + biofilm reactor (reactor B) 31 includes an inlet 311, an outlet 312, a self-circulating outlet 313, and a baffle plate. The baffle plate divides the internal space of reactor B 31 into upper and lower sections. The three-phase separator 37 and biofilm 38 are located in the upper section, while the outlet 312 and the self-circulating outlet 313 are located on the corresponding upper section of reactor B 31's wall. The outlet 312 discharges the water separated by the three-phase separator 37, which is classified as tertiary wastewater. The gas separated by the three-phase separator 37 is discharged through the top opening of reactor B 31. Aeration pipes 34, hydrocyclones 35, and aerobic granular sludge are located at the bottom. Secondary wastewater enters the lower part of reactor B via pump 32 and inlet 311. Blowers 33 aerate the wastewater through aeration pipes 34, and hydrocyclones 35 distribute the water evenly. The upward flow velocity in reactor B 31 is greater than 2 m / h. The aerobic granular sludge is well granulated. In reactor B, ammonia-oxidizing bacteria and denitrifying bacteria are used for short-cut nitrification and denitrification to achieve efficient nitrogen removal, and the phosphorus removal rate is over 90%. Then, the secondary wastewater enters the biofilm 38 treatment section at the top of reactor B for deep nitrogen and phosphorus removal. Reactor B 31 removes ≥95% of nitrogen and phosphorus from the secondary wastewater. The antibiotic concentration in the secondary wastewater is around 20 mg / L. After treatment with aerobic granular sludge and biofilm, the removal rate of antibiotics such as tetracycline is over 90%. The continuous flow aerobic granular sludge + biofilm reactor (reactor B) uses a self-circulating pump 36 for self-recirculation to improve the efficiency of nitrogen removal, phosphorus removal, and antibiotic removal.

[0039] See Figure 4 The Chlorella treatment device 4 includes a Chlorella reactor (reactor C) 41, a water pump 42, and a solar panel 43. Tertiary wastewater is pumped into reactor C 41 via pump 42. The solar panel 43 heats the Chlorella reactor 41, maintaining the temperature at approximately 30 degrees Celsius (suitable for Chlorella growth). The algae further absorb residual nitrogen and phosphorus in the tertiary wastewater. The concentration of the treated tertiary wastewater is lower than the limits specified in the "Emission Standard of Pollutants for Livestock and Poultry Farming" (GB / T18596-2001), allowing it to be stored in a storage tank and reused for toilet flushing or daily cleaning in livestock and poultry farms, thus saving tap water. Chlorella is rich in nutrients such as protein and can be used as an additive in livestock and poultry feed. Alternatively, the powerful CGF active factor in Chlorella can be extracted for use in medical and cosmetic fields, realizing the resource utilization of livestock and poultry farm wastewater.

[0040] The specific process for water treatment is as follows: First, livestock and poultry breeding wastewater passes through a pretreatment device (using a screen to intercept large floating objects carried in the wastewater), and after preliminary settling in a grit chamber, it undergoes solid-liquid separation through a multi-stage drum screen to remove floating objects such as manure. Then, the wastewater enters a flocculation sedimentation tank, where PAC / PAM is added to enhance coagulation. Finally, the wastewater is pumped by an influent pump to the bottom of the UASB reactor (reactor A) for anaerobic biogas production. A stirrer 29 is installed at the bottom of reactor A to rotate the stirring blades 291 to ensure uniform water distribution. The generated biogas is discharged through a three-phase separator 27 and then enters the methane collection and purification component 2. In step 2 (methane yield ≥95%), methane is pumped into the gas boiler 25 via gas flow meter 23 and gas pump 24. The heat generated by methane combustion in the gas boiler is transferred to the UASB reactor 21 via heat exchanger 26. Temperature detector 28 monitors the internal temperature of the UASB reactor 21, maintaining it at approximately 30 degrees Celsius (organic carbon removal rate ≥95%). The livestock wastewater treated in the UASB reactor 21 is pumped into the bottom of the continuous flow aerobic granular sludge + biofilm reactor (reactor B) 31 via pump 32. Aeration is achieved through aeration pipe 34 using blower 33, and uniform water distribution is achieved using hydrocyclone 35. The upward flow velocity in reactor B 31 is greater than 2 m / h, and the aerobic granular sludge is well granulated. In reactor B31, ammonia-oxidizing bacteria and denitrifying bacteria are used for short-cut nitrification and denitrification to achieve efficient nitrogen removal. The wastewater then enters the biofilm 36 treatment section at the top of reactor B31 for deep nitrogen and phosphorus removal. After treatment with aerobic granular sludge and biofilm, antibiotics such as tetracycline are removed. Simultaneously, the continuous flow aerobic granular sludge + biofilm reactor (reactor B) 31 is self-circulated by pump 36 to improve the efficiency of nitrogen, phosphorus, and antibiotic removal. Finally, the treated livestock and poultry wastewater is pumped into the Chlorella reactor (reactor C) 41 via pump 42. The Chlorella reactor is heated by solar panels 43. The temperature is maintained at around 30 degrees Celsius (suitable for Chlorella growth), allowing the algae to further absorb residual nitrogen and phosphorus in livestock and poultry wastewater. The treated wastewater concentrations are all below the limits set by the "Discharge Standard of Pollutants for Livestock and Poultry Farming" (GB / T18596-2001), and can be stored in a water tank for recycling for toilet flushing or daily cleaning in livestock and poultry farms, saving tap water. Chlorella is rich in nutrients such as protein and can be used as an additive in livestock and poultry feed, or its powerful CGF active factors can be extracted for use in medical and cosmetic fields, thus realizing the resource utilization of livestock and poultry wastewater.

[0041] Example 2:

[0042] See Figure 5 A low-carbon synergistic treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater includes the following steps:

[0043] S1: Removes floating matter from livestock and poultry breeding wastewater, separates manure and primary wastewater, and produces biogas and secondary wastewater through anaerobic reaction of primary wastewater.

[0044] Floating solids are removed through interception, filtration, and sedimentation. Particulate matter is further removed by adding coagulants to obtain primary wastewater. This primary wastewater undergoes anaerobic reaction to produce biogas and secondary wastewater. The biogas is used for combustion to insulate the anaerobic reaction, resulting in near-zero greenhouse gas emissions during the water treatment process. Separated excrement and other wastewater are dewatered using a press and can be composted.

[0045] The livestock and poultry breeding wastewater stays in the pretreatment device for about 1 hour. Large floating objects in the wastewater are initially treated using a bar screen and a grit chamber. A multi-stage drum screen separates the solids and liquids in the livestock and poultry breeding wastewater. PAC / PAM is added to the flocculation sedimentation tank to enhance coagulation and improve the pretreatment effect.

[0046] Primary wastewater enters the UASB reactor (reactor A), where the hydraulic retention time (HRT) is 8-11 hours. The HRT can be shortened or extended depending on the removal efficiency of organic matter.

[0047] S2: Secondary wastewater undergoes denitrification, dephosphorization, and antibiotic removal via ammonia-oxidizing bacteria, denitrifying bacteria, and biofilm biological processes, resulting in tertiary wastewater.

[0048] Through a continuous flow aerobic granular sludge + biofilm reactor, ammonia nitrogen in secondary wastewater is converted into nitrite by ammonia-oxidizing bacteria on the outside of the aerobic granular sludge. Then, denitrifying bacteria inside the aerobic granular sludge use the remaining organic carbon in the secondary wastewater to convert nitrite into nitrogen gas, achieving efficient nitrogen removal. The secondary wastewater then enters the biofilm section for deep nitrogen and phosphorus removal, with nitrogen and phosphorus removal rates both exceeding 95%. At the same time, the aerobic granular sludge utilizes its adsorption and degradation functions to remove antibiotics such as tetracycline from livestock and poultry wastewater. The antibiotic concentration in livestock and poultry wastewater is around 20 mg / L, and the removal rate of tetracycline and other antibiotics after aerobic granular sludge and biofilm treatment is over 90%.

[0049] A blower is used to aerate the continuous flow aerobic granular sludge-biofilm reactor (reactor B). The aeration pipe is located at the bottom of reactor B. Livestock and poultry breeding wastewater treated by the UASB reactor (reactor A) is pumped into reactor B from the bottom. Reactor B uses a return pump for self-recirculation, which improves the denitrification and phosphorus removal efficiency. The removal rates of COD, ammonia nitrogen and phosphorus are all above 95%.

[0050] S3: Use algae to further absorb the residual nitrogen and phosphorus in the tertiary wastewater.

[0051] Tertiary wastewater enters the Chlorella reactor, where Chlorella further absorbs nitrogen and phosphorus. While growing, Chlorella also purifies livestock and poultry breeding wastewater.

[0052] After pretreatment and treatment in reactors A and B, the livestock and poultry breeding wastewater enters the Chlorella device in reactor C. Chlorella grows rapidly and has a wide range of adaptability to pH and other parameters. Nitrogen is an important component of Chlorella cells, and phosphorus is one of the essential nutrients for Chlorella growth. Therefore, Chlorella further absorbs and utilizes the remaining nitrogen and phosphorus in the treated livestock and poultry breeding wastewater.

[0053] After the above steps, the livestock and poultry breeding wastewater is stored in a water tank and used for daily flushing of livestock and poultry farms or for flushing toilets. Chlorella is rich in protein, various minerals and trace elements, and can be recycled as an additive for livestock and poultry feed, or the powerful CGF active factor in chlorella can be recycled and extracted for use in medical and cosmetic fields.

[0054] As described above, embodiments of the present invention have been explained in detail. However, many modifications are possible without substantially departing from the inventive points and effects of the present invention, which will be apparent to those skilled in the art. Therefore, all such modifications are also included within the protection scope of the present invention.

Claims

1. A low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater, characterized in that, include: A pretreatment device that removes floating matter from wastewater using physical methods, and then coagulates it with a coagulant to produce primary wastewater. A biogas recovery and utilization device, wherein the primary wastewater undergoes anaerobic reaction in the biogas recovery device to produce biogas and secondary wastewater; The aerobic granular sludge + biofilm device, in which the secondary wastewater undergoes denitrification, dephosphorization and antibiotic removal through the action of aerobic granular sludge and biofilm, producing tertiary wastewater; Chlorella treatment device, wherein the chlorella in the chlorella treatment device further removes residual nitrogen and phosphorus from the tertiary wastewater; The pretreatment device includes a bar screen, a grit chamber, a multi-stage drum screen, a collection tank, a flocculation sedimentation tank, and a press. Wastewater passes through the bar screen to intercept floating matter. After initial settling in the grit chamber, solids are separated from solids by the multi-stage drum screen. The solids are then pressed by the press and used for fermentation. The liquid is mixed with a coagulant and flocculated in the flocculation sedimentation tank to produce primary wastewater. The biogas recovery and utilization device includes a UASB reactor, a methane collection and purification component, a gas boiler, a heat exchanger, and a three-phase separator. The primary wastewater undergoes anaerobic reaction in the UASB reactor to produce biogas and secondary wastewater. After separation by the three-phase separator, the gas is burned in the gas boiler to generate heat, and the heat is transferred to the UASB reactor in the heat exchanger. The aerobic granular sludge + biofilm device includes an aerobic granular sludge + biofilm reactor, a blower, aeration pipes, a hydrocyclone, a self-circulating pump, a three-phase separator, and a biofilm. The secondary wastewater enters the lower part of the aerobic granular sludge + biofilm reactor, where the blower aerates the water through the aeration pipes and the hydrocyclone distributes the water evenly. The secondary wastewater then enters the biofilm treatment section at the top of the aerobic granular sludge + biofilm reactor, generating tertiary wastewater, which can be self-circulated back by the self-circulating pump. The Chlorella treatment device includes a Chlorella reactor, a water pump, and a solar panel. The tertiary wastewater is pumped into the Chlorella reactor by the water pump, and the Chlorella reactor is heated by the solar panel.

2. The low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater as described in claim 1, characterized in that, The biogas recovery and utilization device also includes a gas flow meter, a gas pump, a three-phase separator, a temperature detector, and a stirrer.

3. A low-carbon synergistic treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater, wherein the method is implemented using the low-carbon synergistic treatment system for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater as described in claim 2, characterized in that, Includes the following steps: S1: Use a pretreatment device to remove floating matter from livestock and poultry breeding wastewater and separate manure and primary wastewater. The primary wastewater is then subjected to anaerobic reaction in a biogas recovery and utilization device to produce biogas and secondary wastewater. S2: The secondary wastewater is denitrified, dephosphorized, and antibiotics removed in the aerobic granular sludge + biofilm reactor by ammonia-oxidizing bacteria and denitrifying bacteria, and by the biological action of the biofilm, producing tertiary wastewater; S3: Use a Chlorella reactor to further absorb the residual nitrogen and phosphorus in the tertiary wastewater.

4. The low-carbon synergistic treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater as described in claim 3, characterized in that, S1 includes: The primary wastewater undergoes anaerobic reaction at the bottom of the UASB reactor to produce biogas. The agitator rotates to ensure uniform water distribution. The biogas produced is discharged through the three-phase separator and then enters the methane collection and purification assembly. The methane is pumped into the gas boiler by the gas pump via the gas flow meter. The heat generated by the combustion of methane in the gas boiler is transferred to the UASB reactor through the heat exchanger.

5. The low-carbon synergistic treatment method for efficient nitrogen and phosphorus removal from livestock and poultry breeding wastewater as described in claim 3, characterized in that, S2 includes: The secondary wastewater is pumped into the lower part of reactor B, where it is aerated by the blower through the aeration pipe and evenly distributed by the hydrocyclone. The secondary wastewater then enters the biofilm treatment section.

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