Feces treatment system for pig farm

Abstract

The invention relates to the technical field of wastewater multi-stage treatment, in particular to a pig farm manure treatment system which comprises a pretreatment unit, a solid-phase treatment unit, a liquid-phase treatment unit and a gas-phase treatment unit which are sequentially connected, and material circulation channels are arranged among the units. The solid phase treatment unit comprises a spraying device with an adjustable microbial inoculum ratio and a turning machine with a controllable turning depth; the liquid phase treatment unit comprises a shunting path switchable carbon nitrogen adjusting tank, a flora activity compensable anaerobic fermentation tank and a photocatalysis-constructed wetland coupling subunit; and the gas phase treatment unit comprises a biogas membrane separation tower with adjustable operation pressure and a reflux device with controllable biogas residue reflux proportion. Each treatment unit can be dynamically adjusted according to the actual operation condition and the environment change, so that the adaptability of the system to different excrement types is improved, and the treatment efficiency reduction caused by the environment change is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-stage wastewater treatment, and particularly relates to a pig farm manure treatment system. BACKGROUND

[0002] The water flushing or water soaking manure process used in large-scale pig farms results in highly mixed manure and urine, forming manure with high fiber and high ammonia nitrogen characteristics. The existing technology has the following bottleneck problems: The pig manure contains a large amount of undigested feed fiber (mostly distributed in 5-50 mm), and the fiber material is easily entangled in the screen mesh during processing by the traditional drum screen. When the fiber length is greater than 10 mm, the screen mesh clogging rate is as high as 78%, which causes the moisture content of the solid manure residue to be maintained at more than 80% for a long time, which cannot meet the requirement of the compost process that the moisture content should be less than 60%. This problem directly causes the interruption of the solid resource utilization path.

[0003] Because urea in pig urine is rapidly hydrolyzed into ammonia nitrogen, the COD / N of the mixed liquid of manure and urine is usually less than 10:1. However, the metabolic needs of anaerobic fermentation bacteria maintain COD / N>15:1, and the existing technology has to directly put the manure into the anaerobic tank, resulting in the accumulation of volatile fatty acids and a decrease in methane production rate of more than 40%. This fundamental contradiction between component characteristics and process requirements is the core factor restricting the benefit of the biogas project.

[0004] Therefore, there is an urgent need for a pig farm manure treatment system to solve the above problems. SUMMARY

[0005] In order to achieve the above purposes, the pig farm manure treatment system provided by the present application comprises a pretreatment unit, a solid phase treatment unit, a liquid phase treatment unit and a gas phase treatment unit connected in sequence, and a material circulation channel is arranged between each unit: The pretreatment unit comprises a dynamically adjusted variable-diameter spiral screen, the front section of the spiral shaft of which is an equal-diameter spiral blade, and the rear section is a tapered variable-diameter spiral blade, the blade spacing decreases along the material advancing direction, and the screen mesh adopts a wedge-shaped steel wire woven structure with large size at the top and small size at the bottom; The solid phase treatment unit comprises a spraying device with adjustable bacteria agent ratio and a turning machine with controllable turning depth, the bacteria agent ratio of the spraying device is dynamically selected according to the carbon-nitrogen ratio of the solid manure residue, and the turning depth of the turning machine is adjusted in real time according to the oxygen concentration of the pile; The liquid phase treatment unit comprises a carbon-nitrogen adjusting tank with switchable shunt paths, an anaerobic fermentation tank with compensable bacteria activity, and a photocatalysis-artificial wetland coupling subunit, the shunt paths of the carbon-nitrogen adjusting tank are switched according to the carbon-nitrogen ratio of the liquid phase, the bacteria population temperature is self-adapted through inter-chamber heat exchange of the anaerobic fermentation tank, and the photocatalysis-artificial wetland coupling subunit takes the product of the solid phase treatment unit as the wetland substrate; The gas phase treatment unit comprises a biogas membrane separation tower with adjustable operating pressure and a backflow device with controllable biogas residue backflow ratio, the operating pressure of the biogas membrane separation tower is dynamically adjusted according to the biogas flow, and the backflow device delivers the anaerobic fermentation tank biogas residue to the solid phase treatment unit, and the backflow ratio is controlled according to the organic matter content of the biogas residue.

[0006] Preferably, the tapering screw screen's cone tapering screw blade taper dynamic adjustment process comprises: A torque sensor is installed at the end of the screw shaft to monitor the material pushing resistance in real time; When the pushing resistance continuously increases and exceeds the resistance threshold, the screw blade taper is increased through the hydraulic actuator; When the pushing resistance continuously decreases and is lower than the resistance threshold, the screw blade taper is decreased through the hydraulic actuator; The resistance threshold is determined by a learning model of historical operation data, and the specific steps are as follows: collecting stable operation torque data under different fiber contents of fecal pollution, establishing a fiber content-torque correlation curve, and taking the torque value corresponding to the inflection point of the curve as the dynamic threshold reference.

[0007] Preferably, the dynamic selection process of the bacterial agent ratio comprises: The carbon-nitrogen ratio of solid fecal residue is detected in real time by a near-infrared spectrometer; When the carbon-nitrogen ratio is higher than the first threshold, the bacterial agent nozzle containing lignin-degrading bacteria is started, and the spraying amount is linearly increased according to the fecal residue accumulation thickness; When the carbon-nitrogen ratio is lower than the second threshold, the bacterial agent nozzle containing ammonia-oxidizing bacteria is started, and the spraying amount is exponentially adjusted according to the fecal residue ammonia release rate; The first threshold and the second threshold are calibrated by humification experiments: test the humic acid generation efficiency under different carbon-nitrogen ratios in a controllable environment, and take the carbon-nitrogen ratio corresponding to the inflection point of the efficiency decline as the threshold boundary.

[0008] Preferably, the temperature self-adaptation process of the anaerobic fermentation tank's bacterial flora comprises: A mesophilic bacterial flora is arranged in the outer chamber of the anaerobic fermentation tank, a thermophilic bacterial flora is arranged in the center chamber, and a spiral coil heat exchanger is arranged between the two chambers; The ambient temperature change trend is obtained through an environmental temperature sensor, when the temperature continuously decreases and is lower than the low temperature threshold, the high temperature bacterial flora dominant mode is started: the outer chamber inlet is closed, and the heat medium flow direction of the heat exchanger is switched to the center chamber to the buffer chamber; When the temperature continuously increases and is higher than the high temperature threshold, the mesophilic bacterial flora dominant mode is started: the center chamber stirrer is closed, and the heat medium flow direction of the heat exchanger is switched to the outer chamber to the buffer chamber; The low temperature threshold and the high temperature threshold are determined according to seasonal gas production efficiency decay experiments: the unit COD gas production rate reduction rate in different temperature intervals is recorded, and the critical temperature when the reduction rate exceeds the allowable value is taken as the threshold.

[0009] Preferably, the substrate activation method of the photocatalysis-artificial wetland coupling subunit comprises: The humic acid particles produced by the solid phase treatment unit are crushed to a predetermined particle size range and filled in the root zone of the artificial wetland; A rotatable titanium dioxide / biochar composite carrier plate is arranged in the ultraviolet photocatalytic reactor, and the rotation speed of the carrier plate is controlled according to the ammonia nitrogen concentration of the influent; When the ammonia nitrogen concentration exceeds the concentration threshold, start the short-wavelength ultraviolet light source and increase the rotation speed of the carrier plate; When the ammonia nitrogen concentration is lower than the concentration threshold, start the long-wavelength ultraviolet light source and reduce the rotation speed of the carrier plate; The concentration threshold is determined by photocatalytic kinetics experiments: the mutation point of the degradation rate under different ammonia nitrogen concentrations is determined, and the mutation point concentration is taken as the grading control reference.

[0010] Preferably, the mesh gradient optimization method of the wedge-shaped steel wire woven structure comprises: A high-speed camera is installed at the inlet of the pretreatment unit to continuously collect the floating trajectory of the fiber material in the fecal pollution; The fiber length distribution histogram is extracted by image recognition algorithm, and the length interval corresponding to the histogram peak value is taken as the basis for mesh design; The ratio of the upper aperture to the lower aperture of the mesh is set as a function of the median length of the fibers, and the function relationship is calibrated by screening efficiency test.

[0011] Preferably, the real-time adjustment process of the turning and throwing depth comprises: An oxygen concentration sensor array is buried at different depths of the pile, and the oxygen concentration at the center point is taken as the control signal; When the oxygen concentration at the center point is lower than the oxygen threshold, the hydraulic arm of the turning and throwing machine is controlled to probe to the first depth; When the oxygen concentration at the center point is higher than the saturation threshold, the hydraulic arm of the turning and throwing machine is controlled to lift to the second depth; The oxygen threshold and the saturation threshold are determined by microbial respiration rate experiments: the specific oxygen consumption rate curve of the aerobic microbial community under different oxygen concentrations is measured, and the boundary oxygen concentration of the steep region of the curve is taken as the threshold.

[0012] Preferably, the control process of the biogas residue reflux ratio comprises: The volatile solid content of the biogas residue is detected in real time by the ignition loss method; When the volatile solid content is higher than the activity threshold, increase the reflux ratio to the first proportion value; when the volatile solid content is below the inert threshold, reducing the reflux ratio to a second value; The active threshold and the inert threshold are determined through microbial inoculation experiments: the biogas residue with different organic matter contents is introduced into the solid-phase treatment unit, and the content interval corresponding to the peak of the specific growth rate of the microorganisms is determined as the threshold boundary.

[0013] Preferably, the shunt path switching threshold dynamic correction method of the carbon-nitrogen regulation tank comprises: An online monitor is arranged at the water inlet of the anaerobic fermentation tank to record the COD / N ratio and the methane yield correlation data in real time; When the methane yield is continuously decreased and the decrease slope exceeds the allowable value, a threshold correction instruction is triggered; The COD / N ratio corresponding to the yield decrease inflection point is used as a new threshold to replace the original set value.

[0014] Preferably, the material circulation channel comprises two paths: solid-liquid circulation and liquid-solid circulation. The solid-liquid circulation path: the leachate generated by the solid-phase treatment unit is delivered to the carbon source supplement branch of the liquid-phase treatment unit through a pressure pump; The liquid-solid circulation path: the biogas residue of the gas-phase treatment unit is delivered to the raw material mixing area of the solid-phase treatment unit through a screw conveyor; The start and stop of the two paths are coordinated by the central controller, and the coordination logic is dynamically generated based on the difference between the carbon-nitrogen balance degree of the solid-phase treatment unit and the denitrification efficiency of the liquid-phase treatment unit.

[0015] The beneficial effects of the present application are: 1. The present application adopts a dynamically adjusted variable-diameter spiral screening machine, wherein the shape and structure of the spiral blade can effectively solve the problem of fiber material winding the screen. In addition, the screen adopts a wedge-shaped steel wire weaving structure with large size at the top and small size at the bottom, which optimizes the screening effect and reduces the resistance to small solid materials, thereby effectively reducing the screen clogging rate. This technology can significantly improve the screening efficiency and ensure the normal operation of solid-phase resourceization.

[0016] 2. The present application uses a carbon-nitrogen regulation tank, dynamically adjusts the shunt path according to the carbon-nitrogen ratio in the liquid phase by using the shunt path switchable technology, ensures that the COD / N ratio meets the needs of anaerobic fermentation, and optimizes the metabolic environment of the bacterial flora through the heat exchanger between the chambers in the anaerobic fermentation tank, thereby improving the fermentation efficiency. Through these dynamic adjustment mechanisms, the present application effectively solves the problem of too low COD / N ratio after the fecal pollution enters the anaerobic fermentation tank, avoids the accumulation of volatile fatty acids, improves the methane yield, and enhances the overall benefits of the biogas project.

[0017] 3、The photocatalysis-artificial wetland coupling subunit of the application can be accurately adjusted according to the change of ammonia nitrogen concentration. Through the rotatable titanium dioxide / biochar composite carrier plate in the ultraviolet photocatalytic reactor, the speed of the carrier plate is dynamically adjusted and the wavelength of the ultraviolet light source is changed according to the ammonia nitrogen concentration of the influent. When the ammonia nitrogen concentration is high, start the short-wavelength ultraviolet light source and increase the speed of the carrier plate; when the ammonia nitrogen concentration is low, start the long-wavelength ultraviolet light source and reduce the speed. Through this mechanism, the application can accelerate the degradation process of ammonia nitrogen when the ammonia nitrogen concentration is high, thereby improving the purification efficiency of wastewater.

[0018] 4、The application adjusts the working depth of the flipper in real time according to the oxygen concentration of the pile center point through the real-time adjustment mechanism of the flipper depth. When the oxygen concentration is lower than the oxygen threshold, the hydraulic arm of the flipper is controlled to probe to the first depth; when the oxygen concentration is higher than the saturation threshold, the hydraulic arm of the flipper is lifted to the second depth. Through this real-time adjustment process, the oxygen concentration during composting can be ensured to be always within the appropriate range, thereby improving the composting effect and resource utilization efficiency.

[0019] 5、The application dynamically adjusts the backflow ratio of biogas residue according to the volatile solid content of the biogas residue through real-time monitoring of the volatile solid content. When the volatile solid content is higher than the activity threshold, the backflow ratio is increased; when the volatile solid content is lower than the inert threshold, the backflow ratio is reduced. This flexible backflow ratio control mechanism can ensure that the backflow of biogas residue is always in the best state, thereby improving the biogas production and overall treatment efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0021] Fig. 1 is a block diagram of the system of the application; Fig. 2 is a step flow chart of the taper dynamic adjustment process of the conical variable-diameter spiral blade of the variable-diameter spiral screening machine in the system of the application; Fig. 3 is a step flow chart of the control process of the biogas residue backflow ratio in the system of the application. DETAILED DESCRIPTION

[0022] The application will be described in detail below with reference to the drawings and specific embodiments. It should be noted here that, in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and other alternative ways can also be adopted by those skilled in the art to implement them; and the drawings are only used to more specifically describe the embodiments, and are not intended to specifically limit the application.

[0023] Please refer to Figs. 1-3 The pig farm manure treatment system provided by the embodiments of the application comprises a pretreatment unit, which comprises a variable-diameter spiral screening machine. The front section of the spiral shaft is an equal-diameter spiral blade, and the rear section is a tapered variable-diameter spiral blade, and the blade spacing gradually decreases along the material advancing direction. The screen mesh adopts a wedge-shaped steel wire woven structure with large size at the top and small size at the bottom.

[0024] The equal-diameter spiral blade can keep the material uniformly distributed and effectively avoid material blockage during the initial conveying process of the material; and the tapered variable-diameter spiral blade helps to further screen out larger solid particles.

[0025] The screen mesh adopts a wedge-shaped steel wire woven structure, and the unique design of large size at the top and small size at the bottom effectively improves the screening efficiency, especially for high-water-content manure materials, which avoids the low efficiency caused by blockage of the traditional screen mesh.

[0026] The design can efficiently remove larger solid impurities from the pig manure, reduce the burden of the subsequent treatment unit by optimizing the screening efficiency, reduce the equipment maintenance frequency, and prolong the service life of the equipment.

[0027] The solid-phase treatment unit comprises a spray device with adjustable bacteria agent ratio and a turning machine with adjustable turning depth. The spray device dynamically selects the ratio of bacteria agents according to the carbon-nitrogen ratio of the solid manure; and the turning machine adjusts the turning depth in real time according to the oxygen concentration of the pile.

[0028] The spray device monitors the carbon-nitrogen ratio in the solid manure in real time through a sensor and automatically adjusts the ratio of bacteria agents to ensure the optimal environment for the microbial fermentation process. For example, when the carbon-nitrogen ratio is too high, the nitrogen source bacteria agent is increased; otherwise, the carbon source bacteria agent is increased.

[0029] The turning machine is equipped with an oxygen concentration monitor, which adjusts the turning depth according to the oxygen concentration of the pile. When the oxygen concentration is too low, the turning machine increases the turning depth to enhance the aeration effect and ensure the aerobic composting process.

[0030] The system can realize dynamic regulation and control during the solid treatment process, improve the biodegradation efficiency of the composting process, ensure suitable microbial activity in each stage, reduce odor emission, and accelerate the resource conversion of organic waste.

[0031] The liquid phase treatment unit includes a carbon-nitrogen regulating tank (with switchable diversion paths), an anaerobic fermentation tank with compensable bacterial activity, and a photocatalysis-artificial wetland coupling subunit. The diversion paths of the carbon-nitrogen regulating tank are switched according to the carbon-nitrogen ratio of the liquid phase; the anaerobic fermentation tank realizes self-adaptation of the bacterial population temperature through an inter-chamber heat exchanger; and the photocatalysis-artificial wetland coupling subunit uses the product of the solid phase treatment unit as the wetland substrate.

[0032] The tank monitors the carbon-nitrogen ratio in the liquid phase through an automated system, and when the carbon-nitrogen ratio of the liquid phase is imbalanced, the system automatically adjusts the diversion paths to ensure that the carbon-nitrogen ratio of the treated water body is suitable for subsequent anaerobic fermentation.

[0033] The anaerobic fermentation tank is equipped with a heat exchange device to monitor the temperature of the bacterial population in real time during fermentation, and when the temperature changes, the heat exchange system can automatically adjust the heat distribution between the chambers to keep the bacterial population in an optimal temperature environment.

[0034] The product of the solid phase treatment unit is used as the wetland substrate, and the photocatalytic reaction is used to accelerate the degradation of organic pollutants in the water body, further purifying the aquaculture wastewater.

[0035] The liquid phase treatment unit realizes efficient carbon-nitrogen regulation and temperature self-adaptive management of liquid waste, not only accelerating the degradation process of organic matter, but also using photocatalytic technology to further purify the wastewater, improving the environmental benefits of the system.

[0036] The gas phase treatment unit includes a biogas membrane separation tower with adjustable operating pressure and a reflux device with controllable biogas residue reflux ratio. The operating pressure of the biogas membrane separation tower is dynamically adjusted according to the biogas flow; the reflux device transports the biogas residue in the anaerobic fermentation tank to the solid phase treatment unit, and the reflux ratio is controlled according to the organic matter content of the biogas residue.

[0037] According to the actual biogas flow, the operating pressure of the membrane separation tower is adjusted in real time. This can effectively improve the separation efficiency of biogas and avoid the decline in separation efficiency due to unstable pressure.

[0038] The reflux device dynamically adjusts the reflux ratio by detecting the organic matter content in the biogas residue, ensuring that organic matter can re-enter the solid phase treatment unit to maximize resource recovery.

[0039] By precisely adjusting the operating pressure of the biogas membrane separation tower, the purification efficiency of biogas can be improved, and gas waste can be reduced. The reflux device optimizes the reuse of biogas residue, not only improving the treatment efficiency of the system, but also reducing the loss of organic matter.

[0040] The pig farm manure treatment system realizes efficient treatment of pig manure and gas through accurate design and dynamic adjustment of each unit. The pretreatment unit reduces the material burden through accurate screening; the solid phase treatment unit optimizes the composting process through dynamic adjustment of the ratio of bacterial agents and turning depth; the liquid phase treatment unit ensures the fermentation effect through carbon and nitrogen adjustment and temperature control management; and the gas phase treatment unit realizes the maximization of biogas and biogas residue resources through membrane separation tower and reflux device. This series of innovative design not only improves the treatment efficiency, but also realizes the environmental protection benefit, providing a sustainable waste treatment solution for the breeding industry.

[0041] In one possible implementation, a torque sensor is installed at the end of the screw shaft to monitor the resistance of the material pushing in real time.

[0042] The torque sensor is installed at the end of the screw shaft and is specifically used to monitor the resistance generated when the material is pushed during screening. These data can accurately reflect the flow resistance of the material, and further help to judge the working state of the screw blade.

[0043] The real-time data of the torque sensor is sent to the control system, which judges the difficulty of material pushing according to these data to provide basis for subsequent dynamic adjustment.

[0044] By monitoring the pushing resistance in real time, the system can sense the changes of the material at any time during the screening process, ensuring that the screening process is more flexible and accurate. This design improves the response speed to the characteristics of the material, avoids the problem of uneven material flow or blockage, and improves the screening efficiency and equipment reliability.

[0045] When the pushing resistance continues to increase and exceeds the resistance threshold, the hydraulic actuator is used to increase the taper of the screw blade; when the pushing resistance continues to decrease and is lower than the resistance threshold, the hydraulic actuator is used to reduce the taper of the screw blade.

[0046] The hydraulic actuator automatically adjusts the taper of the screw blade according to the instructions of the control system. Specifically, when the material passes through the screening machine, if there are many solid impurities in the material or the water content is too high, the pushing resistance will increase. At this time, the control system will trigger the hydraulic actuator to increase the taper of the screw blade, thereby reducing the accumulation of the material and reducing the pushing pressure.

[0047] When the pushing resistance decreases below a certain threshold, the hydraulic actuator will adjust the blade taper in the opposite direction to reduce the taper of the screw blade, ensuring that the screening efficiency will not be affected by the low resistance to the working state of the screen.

[0048] The dynamic adjustment process enables the spiral screen machine to adapt to the screening requirements of different materials in real time, avoiding the low efficiency or overload of traditional screening equipment due to changes in material properties. Through precise adjustment of the hydraulic actuator, the system can effectively optimize the screening process, reduce energy consumption, and improve screening accuracy and speed.

[0049] The resistance threshold is determined by a learning model based on historical operation data. The specific steps are as follows: collect stable operation torque data under different fiber content of fecal pollution, establish a fiber content-torque correlation curve, and take the torque value corresponding to the inflection point of the curve as the dynamic threshold reference.

[0050] Through long-term operation and treatment of different types of fecal pollution, the system will collect stable operation torque data under different fiber content. The data collection is not limited to the type of material, but also includes the propulsion resistance of each material under different working conditions.

[0051] By analyzing these data, the system will establish a correlation curve between fiber content and torque, and the inflection point of the curve will be the reference for the dynamic threshold. This threshold is used to determine whether the taper of the spiral blade needs to be adjusted.

[0052] The system continuously monitors the actual torque and compares it with the set dynamic threshold. Once the torque value exceeds or is lower than the set threshold, the hydraulic actuator is immediately triggered for adjustment.

[0053] By establishing a correlation between historical data and actual operation, the system can accurately adjust the resistance threshold according to the characteristics of different materials, without relying on fixed empirical values, which significantly improves the system's adaptability to a variety of materials.

[0054] The dynamic adjustment mechanism is based on actual operation data and historical learning model, which can continuously optimize equipment operation, reduce manual intervention, and improve overall processing efficiency and intelligent level.

[0055] The variable-diameter spiral screen machine in the present application realizes dynamic adjustment of the taper of the spiral blade by combining a torque sensor and a hydraulic actuator, optimizing the screening process. By monitoring the propulsion resistance of the material in real time, the system can automatically adjust the blade taper according to the characteristics of the material to ensure efficient and stable screening. Further, through the threshold determination mechanism based on historical data learning, the system can accurately set the dynamic resistance threshold according to the fiber content of different materials, achieving more intelligent operation. This technical solution not only improves the adaptability and screening efficiency of the equipment, but also greatly reduces energy consumption, prolongs the service life of the equipment, and has significant practical application value.

[0056] In one possible implementation, a near-infrared (NIR) spectrometer is installed in the manure residue conveying or stacking area. The device can non-contact and quickly detect solid materials. By comparing the spectral characteristics of organic matter and nitrogen-containing components in the manure residue, the real-time C / N ratio can be calculated.

[0057] The sampling frequency can be set to several times per minute to realize continuous data stream monitoring. The data is transmitted to the central control unit as the basis for adjusting the type and spraying amount of the bacterial agent.

[0058] When the system detects that the C / N ratio is higher than the first threshold value (indicating that the carbon source is excessive and the degradation is difficult), the control system starts the bacterial agent spraying system containing lignin-degrading bacteria (such as white rot fungi and Trichoderma).

[0059] The spraying amount is linearly increased according to the thickness of the manure residue stack, that is, the thicker the stack, the greater the spraying amount, to ensure that the effective bacteria are diffused to each layer of the stack and promote uniform decomposition.

[0060] When the system detects that the C / N ratio is lower than the second threshold value (indicating that the nitrogen content is high and the carbon source is insufficient, which is easy to produce ammonia), the control system starts the bacterial agent spraying system containing ammonia-oxidizing bacteria (such as Nitrosomonas and Nitrifying bacteria).

[0061] The spraying amount is adjusted according to the exponential rate of ammonia release, that is, the more intense the release, the higher the concentration of ammonia nitrogen, and the greater the number of ammonia-oxidizing bacteria required, and the spraying amount is automatically matched according to the exponential function.

[0062] The first and second C / N threshold values are not artificially set, but are obtained under laboratory conditions through humification experiments.

[0063] Under the conditions of controlling temperature and humidity and ventilation, different C / N ratio manure samples are added and standard bacterial agents are added, and the humic acid generation efficiency of each group is recorded within a certain period (such as 15 days).

[0064] The C / N ratio and humic acid generation efficiency curve is drawn, and the inflection point of the efficiency is found. The C / N values on both sides of the inflection point are the threshold limits required for dynamic adjustment.

[0065] By introducing near-infrared real-time detection, dynamic selection mechanism of functional bacterial agents, and data-driven threshold calibration method, the problem of extensive selection of bacterial agents and reaction lag in traditional manure treatment process is solved, and precise regulation and efficient resource utilization of manure decomposition process are realized. The system not only has outstanding environmental benefits, but also has wide application value in intelligent agriculture, green breeding, etc.

[0066] In one possible implementation, the anaerobic fermentation tank includes an outer chamber and a central chamber, where the outer chamber mainly accommodates mesophilic bacteria groups, and the central chamber is configured to accommodate thermophilic bacteria groups. A spiral coil heat exchanger is provided between the two chambers, and the temperature in the chambers is adjusted by the flow of the heat medium of the heat exchanger. By controlling the temperature change, the optimal environment for the growth of bacteria groups and the fermentation reaction is achieved.

[0067] The ambient temperature sensor is used to monitor the change of the external ambient temperature in real time, and adjust the temperature in the fermentation tank according to the change trend of the temperature. The specific process is as follows: When the external temperature continuously falls below the preset low temperature threshold, the thermophilic bacteria group dominant mode is started. At this time, the feed inlet of the outer chamber is closed, and the heat medium in the heat exchanger is guided from the central chamber to the buffer chamber, and through the action of the thermophilic bacteria group, the temperature stability of the fermentation process is ensured, and the methane production efficiency is improved.

[0068] When the external temperature continuously rises above the preset high temperature threshold, the mesophilic bacteria group dominant mode is started. At this time, the agitator of the central chamber is closed, and the heat medium of the heat exchanger is guided to the outer chamber to the buffer chamber, and the environment suitable for the growth of the mesophilic bacteria group is adjusted to maintain the stable fermentation temperature.

[0069] The low temperature threshold and the high temperature threshold are calibrated through seasonal gas production efficiency decay experiments. The experimental steps include recording the unit COD (chemical oxygen demand) gas production rate reduction under different temperature intervals. As the temperature changes, the gas production efficiency also changes, and research has found that when the gas production efficiency reduction rate exceeds a certain critical value, the temperature is considered to have entered the critical interval. At this time, the temperature threshold is defined as the low temperature threshold and the high temperature threshold, which is used to adjust the temperature control strategy in the anaerobic fermentation process.

[0070] By optimizing the fermentation process through temperature adjustment, the anaerobic fermentation tank can efficiently and stably operate under different external temperature conditions, improving the reliability and environmental adaptability of the system.

[0071] In one possible implementation, in the solid phase treatment unit, humic acid particles are produced after certain treatment. These particles have good adsorption and reactivity and can effectively participate in the degradation of ammonia nitrogen in the photocatalytic process.

[0072] The humic acid particles are broken to a predetermined particle size range (usually between a few millimeters and a few microns), to ensure that the surface area of the particles is suitable for good contact with the root system of the wetland plants. Then the particles are filled in the root zone of the constructed wetland as the growth substrate of the wetland plants, to increase their reactivity and treatment capacity.

[0073] The ultraviolet photocatalytic reactor is provided with a rotatable titanium dioxide / biochar composite carrier plate. The titanium dioxide and biochar composite carrier can effectively adsorb and catalyze the decomposition of ammonia nitrogen, and the rotating carrier plate can improve the reaction efficiency and enhance the uniformity of light.

[0074] The rotation speed of the carrier plate is controlled according to the ammonia nitrogen concentration in the influent. The higher the ammonia nitrogen concentration, the more pollutants, and the system needs a higher catalytic reaction rate. Therefore, the rotation speed of the carrier plate will be automatically adjusted according to the concentration to adapt to the treatment demand under different pollution loads.

[0075] When the ammonia nitrogen concentration exceeds the predetermined concentration threshold, the system starts the short-wavelength ultraviolet light source and increases the rotation speed of the carrier plate. Short-wavelength ultraviolet light can excite titanium dioxide catalyst to promote the decomposition of ammonia nitrogen and improve reaction efficiency. At the same time, increasing the rotation speed of the carrier plate can improve the mixing effect of the reactor and enhance the rate of catalytic reaction.

[0076] When the ammonia nitrogen concentration is lower than the concentration threshold, the system starts the long-wavelength ultraviolet light source and reduces the rotation speed of the carrier plate. Long-wavelength ultraviolet light has weak excitation effect on the catalyst, which is suitable for mild reaction under low ammonia nitrogen concentration, thereby saving energy and preventing over-treatment.

[0077] The concentration threshold is determined by photocatalytic kinetics experiments. By measuring the degradation rate under different ammonia nitrogen concentrations, the variation law of reaction rate is analyzed. When the ammonia nitrogen concentration reaches a certain critical point, the degradation rate changes abruptly (such as sharply decreasing or increasing), and the concentration at this time is regarded as the control threshold of the system.

[0078] According to the experimental results, the mutation points under different ammonia nitrogen concentrations are determined, and these mutation points are used as the basis for hierarchical control. This method can ensure that the system can operate efficiently under different pollution levels and avoid over-treatment or insufficient treatment.

[0079] Through the innovative photocatalytic and constructed wetland coupling technology, efficient removal of ammonia nitrogen in pig farm fecal pollution is achieved, with the advantages of intelligent adjustment and energy saving and environmental protection, greatly improving the treatment capacity and operation efficiency of the system.

[0080] In one possible implementation, a high-speed camera is installed at the inlet of the pretreatment unit, mainly used for continuously collecting the floating trajectory of fiber materials in fecal pollution. The motion trajectory of these fiber materials in fecal pollution is a key basis for optimizing the mesh design.

[0081] The high-speed camera can obtain the motion speed, direction, and floating time of the fibers by capturing the motion trajectory of different fibers in fecal pollution in real time, which helps to understand the distribution and characteristics of fiber materials.

[0082] The acquired video data is processed using image recognition algorithms to extract the length distribution information of the fibrous material. The algorithm first identifies each fibrous material object in the video and calculates its length.

[0083] Subsequently, a length distribution histogram was generated using the extracted fiber length information. The peak values ​​of the histogram represent the length ranges that occur most frequently in the fiber material, providing a reference for mesh design.

[0084] Histogram analysis can identify which fiber length segments are most common in fecal matter, allowing this characteristic to be considered in subsequent mesh design to ensure that the designed mesh can efficiently trap or filter fibers within these size ranges.

[0085] Based on the histogram of fiber length distribution, the length range corresponding to the peak value is used as the basis for mesh design. Specifically, the selection of this length range determines the mesh size, thereby optimizing the mesh size and shape to filter out most of the fibrous material to the greatest extent possible.

[0086] For the mesh of a wedge-shaped wire braided structure, the ratio of the upper aperture to the lower aperture is set as a function of the median fiber length. The median reflects the central value of the fiber length and can serve as a reasonable benchmark for designing the mesh gradient.

[0087] The functional relationship was calibrated through a sieving efficiency test. This test, conducted under actual operating conditions, involved continuously adjusting the mesh size to test the sieving effect and ultimately determine the optimal functional relationship. This optimization process ensures that the mesh achieves the best filtration effect regardless of fiber length.

[0088] By analyzing fiber length distribution using image recognition algorithms and combining this with screening efficiency tests to perform gradient optimization of mesh design, the screening efficiency, adaptability, and economy of the system are significantly improved, which helps to enhance the overall operational performance of the manure treatment system in pig farms.

[0089] In one possible implementation, an array of oxygen concentration sensors is embedded at different depths within the pile. These sensors can monitor the oxygen concentration at different levels within the pile in real time to obtain accurate oxygen distribution data. In particular, the sensor at the center point of the array will serve as the primary control signal source for adjusting the tumbling depth.

[0090] The oxygen concentration at the center point reflects the most critical oxygen level within the pile. Therefore, the system will adjust the working depth of the turning machine in real time based on the changes in oxygen concentration at this point to ensure that the aerobic environment within the pile is always in the optimal state.

[0091] When the center point oxygen concentration is below the set aerobic threshold, it means that the aerobic microorganisms in the pile may enter an anaerobic state due to lack of oxygen, affecting the fermentation effect of the pile. At this time, the control system will instruct the hydraulic arm of the turner to probe to the first depth, increase the turning frequency and depth of the pile, and allow more air to enter the pile to promote the diffusion of oxygen and the activity of aerobic microorganisms.

[0092] When the center point oxygen concentration is above the set saturation threshold, it means that the oxygen content in the pile has reached or is close to saturation, and too much oxygen in the pile may cause unnecessary energy waste. To avoid this situation, the hydraulic arm of the turner will be lifted to the second depth, thereby reducing the intensity and frequency of turning to avoid excessive agitation of the pile and maintaining an appropriate oxygen concentration.

[0093] The aerobic threshold and saturation threshold are determined through a microbial respiration rate experiment. In this experiment, the specific oxygen consumption rate of the aerobic microbial community under different oxygen concentrations is measured to obtain the relationship between the respiration behavior of the microorganisms and the oxygen concentration.

[0094] The specific oxygen consumption rate and oxygen concentration curve is drawn through experimental data. This curve shows the change in microbial activity at different oxygen concentrations. When the oxygen concentration is low, the respiration rate of the microorganisms increases rapidly, and when the oxygen concentration approaches saturation, the respiration rate of the microorganisms tends to be stable. The steep change region of the curve is the demarcation point of the aerobic threshold and the saturation threshold, corresponding to the minimum requirement and maximum acceptable value of the oxygen concentration, respectively.

[0095] Through threshold control based on the oxygen concentration sensor array and the microbial respiration rate experiment, real-time adjustment of the turning depth can effectively improve the fermentation efficiency of the pile, optimize energy use, improve system stability, and promote efficient treatment of pig farm manure.

[0096] In one possible implementation, the ignition loss method is used as a method for real-time detection of the volatile solid content of the biogas residue. This method heats a certain amount of biogas residue sample to a high temperature (550°C in the embodiment of the present invention) to completely burn the organic matter in it, thereby determining the content of volatile solids. Volatile solids mainly refer to organic matter in biogas residue, which is a key indicator of organic matter decomposition and microbial activity.

[0097] This process continuously monitors the volatile solid content in the biogas residue to real-time understand the activity state of the organic matter in the biogas residue, providing data support for subsequent reflux ratio adjustment.

[0098] When the volatile solid content detected in real time exceeds the set active threshold, it indicates that the organic matter in the biogas residue has a higher activity, the activity of microorganisms is stronger, and the decomposition process of the biogas residue has not been completed. At this time, in order to enhance the decomposition effect of microorganisms, it is necessary to increase the reflux ratio to ensure that more biogas residue is re-introduced into the solid-phase treatment unit for further treatment. At this time, the reflux ratio is increased to the first ratio value to enhance the organic matter degradation capacity of the reactor.

[0099] When the volatile solid content is lower than the set inert threshold, it indicates that the organic matter in the biogas residue has been relatively stable, the activity of microorganisms is lower, and the decomposition process has been close to completion. At this time, the reflux ratio is reduced to the second ratio value to reduce unnecessary reflux, improve the processing efficiency of the system, and avoid over-treatment.

[0100] The active threshold and the inert threshold are determined through microbial inoculation experiments. In the experiment, biogas residues with different organic matter contents are introduced into the solid-phase treatment unit to simulate the actual fermentation and decomposition process.

[0101] By measuring the specific growth rate of microorganisms under different organic matter contents, the growth rate curve of microorganisms can be obtained. The peak value of the curve represents the optimal growth state of microorganisms, and the corresponding organic matter content interval is the boundary of the active threshold and the inert threshold.

[0102] Above the active threshold, the growth rate of microorganisms is at a peak state, indicating that the organic matter still has a high degradation potential; below the inert threshold, the growth rate of microorganisms decreases, indicating that the decomposition process of organic matter has been close to completion, and the activity of microorganisms has significantly weakened.

[0103] Based on the real-time detection of volatile solid content and the thresholds determined by microbial inoculation experiments, the system can effectively improve the treatment efficiency of biogas residue, save resources, optimize the degradation effect of microorganisms, and enhance the intelligence and automation of the system, ensuring that the pig farm manure treatment system operates efficiently, economically, and environmentally friendly.

[0104] In one possible implementation, an online monitor is installed at the water inlet of the anaerobic fermentation tank to monitor water quality parameters in real time. The online monitor can accurately measure the chemical oxygen demand (COD) and nitrogen (N) content in the influent, and calculate the COD / N ratio. This ratio is a key indicator for measuring the degradation capacity of organic matter and the balance of nitrogen source supply.

[0105] At the same time, the monitor also records the methane production rate, i.e., the amount of methane gas generated during the anaerobic fermentation process. Methane production rate is an important indicator of anaerobic fermentation reaction effect, reflecting the activity of microorganisms in degrading organic matter.

[0106] The system establishes a dynamic relationship model between the COD / N ratio and the methane production rate by continuously recording the correlation data between the two. Through these data, the trend of methane production rate under different COD / N ratios can be analyzed, thereby judging the efficiency of the anaerobic fermentation reaction.

[0107] This process helps to monitor the state of the anaerobic fermentation reaction in real time, ensuring that the microbial community can exert the best degradation efficiency under different carbon-nitrogen ratios.

[0108] When the methane production rate is continuously decreasing and the slope of the decrease exceeds the set allowable value, the system determines that the anaerobic reaction is in an abnormal state, triggering a threshold correction instruction. At this time, the system automatically starts the dynamic correction program to timely adjust the carbon-nitrogen ratio threshold, ensuring the reaction process returns to normal.

[0109] Specifically, when the methane production rate continuously decreases to a certain critical point, the system analyzes the COD / N ratio corresponding to the inflection point of the decrease and uses it as the new shunt path switching threshold, replacing the originally set static threshold. This dynamic adjustment can flexibly respond to changes in methane production rate caused by environmental changes, fluctuations in raw material composition, etc. in the anaerobic reaction.

[0110] Whenever the threshold correction instruction is triggered, the system introduces the new COD / N ratio into the control algorithm of the carbon-nitrogen adjustment tank to adjust the switching strategy of the shunt path in real time. In this way, the treatment system can always maintain the best operating state under different wastewater qualities and reaction conditions.

[0111] In addition, the system's adjustment is gradual to avoid system fluctuations caused by excessive adjustment. Through continuous monitoring and correction, the stability and efficiency of the system are ensured.

[0112] The dynamic correction method of the shunt path switching threshold of the carbon-nitrogen adjustment tank can dynamically adjust system operating parameters by continuously monitoring the correlation data between the COD / N ratio and the methane production rate, thereby optimizing treatment effects, improving system stability, saving resources, and enhancing the intelligence and automation level of the system, with significant economic and environmental benefits.

[0113] In one possible implementation, the solid-phase treatment unit (such as a solid waste treatment area) produces leachate containing a certain amount of dissolved organic matter and available carbon sources through treatment. These leachate are delivered to the carbon source supplement branch of the liquid-phase treatment unit (such as a liquid wastewater treatment area) through a pressurized pump. In this process, the leachate are used as a supplemental carbon source to provide further anaerobic fermentation, denitrification, or other treatment reactions to the liquid-phase treatment unit.

[0114] The start and stop of the pressurized pump is controlled by the central controller to ensure that the leachate flow rate meets the carbon source demand of the liquid treatment unit. By dynamically adjusting the leachate delivery rate, the liquid treatment unit can maintain a relatively stable carbon source supply.

[0115] The biogas residue generated in the gas phase treatment unit (e.g., biogas production area) is transported to the raw material mixing area of the solid phase treatment unit via a screw conveyor. As a solid waste containing abundant organic matter, biogas residue can provide the necessary raw material support for the solid phase treatment unit, helping to improve the efficiency of solid phase treatment.

[0116] The delivery rate of biogas residue can be adjusted according to the needs of the solid phase treatment unit by starting and stopping the screw conveyor. The start and stop of this path is coordinated by the central controller, which dynamically adjusts according to the difference between the carbon-nitrogen balance of the solid phase treatment unit and the nitrogen removal efficiency of the liquid phase treatment unit.

[0117] The central controller monitors the difference between the carbon-nitrogen balance (i.e., the ratio of carbon and nitrogen in the system) of the solid phase treatment unit and the nitrogen removal efficiency (i.e., the removal rate of nitrogen) of the liquid phase treatment unit in real time. Carbon-nitrogen balance is an important indicator affecting treatment efficiency, and appropriate carbon source can improve the degradation efficiency of microorganisms. Nitrogen removal efficiency directly affects the removal of nitrogen source in the water treatment process.

[0118] Based on the above monitoring data, the central controller dynamically generates start and stop strategies. For example, when the carbon-nitrogen balance of the solid phase treatment unit is low, the central controller will increase the leachate delivery rate of the solid-liquid circulation path to ensure that the liquid phase treatment unit has sufficient carbon source support; at the same time, when the nitrogen removal efficiency of the liquid phase treatment unit is high, the central controller may slow down the delivery speed of biogas residue in the liquid-solid circulation path to optimize the solid phase treatment effect.

[0119] The coordinated work of the solid-liquid and liquid-solid circulation paths not only improves the resource utilization rate of the system, but also greatly improves the overall treatment effect and operation efficiency, while ensuring that the pig farm manure treatment system can maintain a stable working state under variable operating conditions.

[0120] The present application encompasses any substitutions, modifications, equivalent methods and solutions made to the essence and scope of the present application. In order for the public to have a thorough understanding of the present application, specific details are described in the following preferred embodiments of the present application, and the present application can also be fully understood without these details by those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits, etc. are not described in detail.

[0121] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A manure treatment system for pig farms, characterized in that: It includes a pretreatment unit, a solid-phase treatment unit, a liquid-phase treatment unit, and a gas-phase treatment unit connected in sequence, with material circulation channels between each unit: The pretreatment unit includes a dynamically adjustable variable diameter spiral screen, with equal diameter spiral blades at the front of the spiral shaft and conical variable diameter spiral blades at the rear. The blade spacing decreases along the material propulsion direction, and the screen adopts a wedge-shaped steel wire woven structure with a larger upper section and a smaller lower section. The solid phase treatment unit includes a spraying device with adjustable microbial agent ratio and a turning machine with controllable turning depth. The microbial agent ratio of the spraying device is dynamically selected according to the carbon-nitrogen ratio of the solid manure residue, and the turning depth of the turning machine is adjusted in real time according to the oxygen concentration of the pile. The liquid phase treatment unit includes a carbon-nitrogen conditioning tank with switchable flow paths, an anaerobic fermenter with compensable microbial activity, and a photocatalysis-constructed wetland coupling subunit. The flow path of the carbon-nitrogen conditioning tank is switched according to the liquid phase carbon-nitrogen ratio. The anaerobic fermenter achieves microbial temperature self-adaptation through inter-chamber heat exchange. The photocatalysis-constructed wetland coupling subunit uses the solid phase treatment unit product as the wetland substrate. The gas phase treatment unit includes a biogas membrane separator with adjustable operating pressure and a reflux device with controllable biogas residue reflux ratio. The operating pressure of the biogas membrane separator is dynamically adjusted according to the biogas flow rate. The reflux device transports the biogas residue from the anaerobic digester to the solid phase treatment unit, and the reflux ratio is controlled according to the organic matter content of the biogas residue.

2. The pig farm manure treatment system according to claim 1, characterized in that: The dynamic adjustment process of the tapered variable diameter spiral blades of the variable diameter spiral screen includes: A torque sensor is installed at the end of the screw shaft to monitor the material propulsion resistance in real time. When the propulsion resistance continues to increase and exceeds the resistance threshold, the cone of the helical blades is increased by the hydraulic actuator. When the propulsion resistance continues to decrease and falls below the resistance threshold, the cone angle of the helical blades is reduced by the hydraulic actuator. The resistance threshold is determined by a learning model based on historical operating data. The specific steps are as follows: collect stable operating torque data under different fecal fiber contents, establish a fiber content-torque correlation curve, and use the torque value corresponding to the inflection point of the curve as a dynamic threshold benchmark.

3. The pig farm manure treatment system according to claim 1, characterized in that: The dynamic selection process of the inoculant ratio includes: The carbon-to-nitrogen ratio of solid fecal residue was detected in real time using a near-infrared spectrometer. When the carbon-nitrogen ratio is higher than the first threshold, the spray nozzle containing lignin-degrading bacteria is activated, and the spraying amount increases linearly with the thickness of the manure accumulation. When the carbon-nitrogen ratio is lower than the second threshold, start the spray nozzle containing ammonia-oxidizing bacteria, and adjust the spraying amount according to the ammonia release rate index of the manure residue. The first and second thresholds are calibrated through humification experiments: the efficiency of humic acid generation is tested under different carbon-nitrogen ratios in a controlled environment, and the carbon-nitrogen ratio corresponding to the inflection point of efficiency decline is used as the threshold boundary.

4. The pig farm manure treatment system according to claim 1, characterized in that: The microbial community temperature adaptive process in the anaerobic fermenter includes: Mesophilic bacteria are placed in the outer chamber of the anaerobic fermenter, and thermophilic bacteria are placed in the central chamber. A spiral coil heat exchanger is installed between the two chambers. By acquiring the trend of external temperature changes through an ambient temperature sensor, when the temperature continues to be below the low temperature threshold, the high temperature microbial community-dominated mode is activated: the feed inlet of the outer chamber is closed, and the heat medium flow direction of the heat exchanger is switched to the central chamber to the buffer chamber. When the temperature remains above the high temperature threshold, the mesophilic microbial community-dominated mode is activated: the central chamber stirrer is turned off, and the heat exchanger heat medium flow direction is switched from the outer chamber to the buffer chamber. The low temperature threshold and high temperature threshold are determined based on a seasonal gas production efficiency decay experiment: the rate of decrease in unit COD gas production is recorded in different temperature ranges, and the critical temperature at which the rate of decrease exceeds the allowable value is taken as the threshold.

5. The pig farm manure treatment system according to claim 1, characterized in that: The matrix activation method of the photocatalytic-artificial wetland coupling subunit includes: The humic acid particles produced by the solid phase treatment unit are crushed to a predetermined particle size range and filled into the root zone of the artificial wetland. A rotatable titanium dioxide / biochar composite support plate is set in the ultraviolet photocatalytic reactor, and the rotation speed of the support plate is controlled in stages according to the ammonia nitrogen concentration of the influent. When the ammonia nitrogen concentration exceeds the concentration threshold, the short-wavelength ultraviolet light source is activated and the carrier plate rotation speed is increased. When the ammonia nitrogen concentration is below the concentration threshold, the long-wavelength ultraviolet light source is activated and the carrier plate rotation speed is reduced. The concentration threshold was determined through photocatalytic kinetic experiments: the mutation point of the degradation rate at different ammonia nitrogen concentrations was measured, and the concentration at the mutation point was used as the grading control benchmark.

6. The pig farm manure treatment system according to claim 1, characterized in that: The mesh gradient optimization method for the wedge-shaped steel wire braided structure includes: A high-speed camera is installed at the inlet of the pretreatment unit to continuously collect the floating trajectory of fibrous materials in the feces. The fiber length distribution histogram is extracted using an image recognition algorithm, and the length interval corresponding to the peak value of the histogram is used as the basis for mesh design. The ratio of the upper aperture to the lower aperture of the mesh is set as a function of the median fiber length, and the functional relationship is calibrated through screening efficiency tests.

7. The pig farm manure treatment system according to claim 1, characterized in that: The real-time adjustment process of the tumbling depth includes: An array of oxygen concentration sensors is buried at different depths in the pile body, and the oxygen concentration at the center point is used as the control signal. When the oxygen concentration at the center point is lower than the oxygen demand threshold, control the hydraulic arm of the turner to descend to the first depth; When the oxygen concentration at the center point is higher than the saturation threshold, control the hydraulic arm of the turner to rise to the second depth; The oxygen demand threshold and saturation threshold were determined through a microbial respiration rate experiment: the specific oxygen consumption rate curves of aerobic microbial communities at different oxygen concentrations were measured, and the oxygen concentration at the boundary of the steep change zone of the curve was used as the threshold.

8. The pig farm manure treatment system according to claim 1, characterized in that: The process for controlling the proportion of biogas residue recirculation includes: The volatile solids content of biogas residue was detected in real time using the loss on ignition method; When the volatile solids content is higher than the activity threshold, increase the reflux ratio to the first ratio value; When the volatile solids content is below the inert threshold, reduce the reflux ratio to the second ratio value; The activity threshold and inert threshold were determined through a microbial inoculation experiment: biogas residues with different organic matter contents were introduced into the solid phase treatment unit, and the content range corresponding to the peak of the microbial specific growth rate was measured as the threshold boundary.

9. The pig farm manure treatment system according to claim 1, characterized in that: The dynamic correction method for the diversion path switching threshold of the carbon-nitrogen conditioning tank includes: An online monitoring instrument was installed at the inlet of the anaerobic digester to record the correlation data between the COD / N ratio and methane yield in real time. When a continuous decrease in methane yield is detected and the rate of decrease exceeds the allowable value, a threshold correction command is triggered. Replace the original set value with the COD / N ratio corresponding to the inflection point of the yield decline as the new threshold.

10. The pig farm manure treatment system according to claim 1, characterized in that: The material circulation channel includes two paths: solid-liquid circulation and liquid-solid circulation. Solid-liquid circulation path: The leachate generated by the solid phase treatment unit is transported to the carbon source replenishment branch of the liquid phase treatment unit via a pressurized pump; Liquid-solid circulation path: The biogas residue from the gas phase treatment unit is transported to the raw material mixing zone of the solid phase treatment unit via a screw conveyor; The start and stop of the two paths are coordinated by the central controller. The coordination logic is dynamically generated based on the difference between the carbon-nitrogen balance of the solid phase treatment unit and the denitrification efficiency of the liquid phase treatment unit.

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