Livestock farm manure liquid ecological treatment system

Abstract

The application discloses a liquid ecological treatment system for livestock and poultry farm manure, which realizes global collaborative control between units of the system by feeding back and feeding forward combined correlation of water quality parameters of effluent from a hydrolysis acidification unit and operation parameters of a multi-stage ecological purification unit through a water quality response model built in an intelligent control unit. Compared with the mode of independent operation of units in the prior art, the application significantly improves the adaptive capacity of the system to respond to fluctuation of water inflow load.

Description

Technical Field

[0001] This invention relates to the field of livestock and poultry breeding technology, and in particular to an ecological treatment system for liquid manure from livestock and poultry farms. Background Technology

[0002] With the rapid development of my country's livestock and poultry farming industry towards intensification and large-scale operations, the treatment of livestock manure liquid has become increasingly prominent. Livestock and poultry manure liquid is characterized by high organic matter concentration, an imbalanced carbon-nitrogen ratio, large fluctuations in water volume, and the presence of numerous pathogenic microorganisms. Direct discharge without proper treatment will cause serious pollution to surrounding water bodies and soil environments. Currently, the main treatment technologies for livestock and poultry manure liquid include anaerobic digestion, aerobic biological treatment, and constructed wetland purification processes; however, many technical bottlenecks still exist in practical engineering applications.

[0003] Chinese patent application CN201710944214.8 discloses a liquid ecological treatment system for livestock and poultry farm manure, comprising source-separation water-saving pens, a pollution treatment plant, a feed mill, and supporting planting land. The pollution treatment plant includes source-separation water-saving pens, a solid high-temperature aerobic fermentation system, a liquid mesophilic anaerobic fermentation system, a heating and heat balance system, and a detection and control system. A regulating tank is connected to the inlet of the liquid mesophilic anaerobic fermentation system via a pump, transporting the biogas produced by the liquid mesophilic anaerobic fermentation system to the heating and heat balance system. The heating and heat balance system is connected to the heating coil of the liquid mesophilic anaerobic fermentation system via pipelines. This invention uses the finished products of the pollution treatment plant—liquid organic-inorganic compound fertilizer and liquid microbial fertilizer—for irrigating and drip-irrigating crops grown on the supporting planting land, while forage grass serves as feed raw material for the feed mill, reducing costs for livestock farming, improving the nutritional level of feed, and promoting the harmonious development of the livestock industry and the ecological environment.

[0004] Chinese patent application CN202411760304.8 discloses a livestock and poultry wastewater purification device and its application, relating to the field of livestock and poultry wastewater purification technology. The device includes a first separation chamber with a first separation mechanism connected to its bottom by a slag discharge mechanism, and a second separation chamber with a second separation mechanism. The second separation chamber contains a peristaltic pump mechanism that transfers the separated liquid into the second separation chamber. A drive motor is located at the top of the first separation chamber. The drive motor synchronously operates the first and second separation mechanisms, allowing wastewater in the first separation chamber to enter the top of the first separation chamber under the influence of the first separation mechanism. This allows sediment in the wastewater to be blocked by a graphite filter layer, and the wastewater then enters the second separation chamber, where the second separation mechanism mixes the wastewater with the chemical solution, thus performing secondary purification. This makes the device more convenient for wastewater purification.

[0005] In summary, existing technologies for treating livestock and poultry manure liquids generally suffer from the following defects: They lack mechanisms for diverting and regulating the flow based on the water quality differences between different sources (high-concentration manure and low-concentration flushing water), leading to excessive dilution of high-concentration organic liquids and increased energy consumption, or the incorrect entry of low-concentration flushing water into the anaerobic system, resulting in resource waste; and they lack synergistic control mechanisms based on carbon-nitrogen ratio feedback between aerobic treatment units and anaerobic digestion units, making it difficult to solve the problem of low carbon-nitrogen ratios in livestock and poultry manure liquids limiting biological nitrogen removal efficiency. Summary of the Invention

[0006] In view of the above-mentioned shortcomings in the prior art, the present invention provides an ecological treatment system for liquid manure from livestock and poultry farms, the purpose of which is to solve the above-mentioned problems.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: an ecological treatment system for liquid manure from livestock and poultry farms, comprising: a source separation unit configured to receive raw manure liquid and separate it into a high-concentration solid phase and a low-concentration liquid phase based on density differences;

[0008] The hydrolysis acidification unit is connected to the liquid phase outlet of the source separation unit and is used to perform anoxic hydrolysis on the low-concentration liquid phase to break down organic macromolecules into volatile fatty acids and simultaneously release bound ammonia nitrogen.

[0009] The multi-stage ecological purification unit includes, in sequence along the liquid flow direction, at least one anoxic denitrification zone, at least one aerobic nitrification zone, and at least one plant absorption zone. The anoxic denitrification zone receives the effluent from the hydrolysis acidification unit and uses the volatile fatty acids as a carbon source for denitrification. The aerobic nitrification zone treats the denitrification effluent with nitrification. The plant absorption zone uses the roots of aquatic plants to absorb residual nutrients.

[0010] A reuse buffer unit is connected to the end outlet of the multi-stage ecological purification unit to temporarily store the purified water and supply it back to the source separation unit or external flushing pipeline according to the water demand of the plant area.

[0011] The intelligent control unit is connected to the source separation unit, the hydrolysis acidification unit, the multi-stage ecological purification unit, and the reuse buffer unit. The intelligent control unit dynamically adjusts the flow ratio of the source separation unit, the internal circulation flow rate of the multi-stage ecological purification unit, and the return supply ratio of the reuse buffer unit based on the effluent water quality parameters of the hydrolysis acidification unit and the dissolved oxygen and oxidation-reduction potential of each zone of the multi-stage ecological purification unit.

[0012] Preferably, in the multi-stage ecological purification unit, a gas-liquid isolation baffle structure is provided between the at least one-stage anoxic denitrification zone and the at least one-stage aerobic nitrification zone. The gas-liquid isolation baffle structure causes the dissolved oxygen generated in the nitrification zone to be consumed during the liquid phase mass transfer process, so as to maintain the anaerobic environment of the anoxic denitrification zone. At the same time, part of the nitrified liquid in the aerobic nitrification zone is returned to the inlet of the anoxic denitrification zone through an internal circulation pipe. The return flow rate is adjusted in real time by the intelligent control unit according to the carbon-nitrogen ratio of the anoxic denitrification zone.

[0013] Preferably, the plant absorption zone is divided into a shallow water root zone and a deep water floating bed zone along the liquid flow direction. The shallow water root zone is planted with emergent plants and has a first hydraulic residence time, while the deep water floating bed zone is planted with floating plants and has a second hydraulic residence time. The first hydraulic residence time is shorter than the second hydraulic residence time, and the effluent from the shallow water root zone enters the deep water floating bed zone through a drop weir to enhance the nitrification assistance effect of the deep water floating bed zone by utilizing the drop weir for reoxygenation.

[0014] Preferably, an intermediate regulating tank is provided between the hydrolysis acidification unit and the multi-stage ecological purification unit. The intermediate regulating tank receives the effluent from the hydrolysis acidification unit and regulates its pH and alkalinity. The regulated effluent is intermittently transported to the anoxic denitrification zone in a pulse manner. The period and amplitude of the pulse are dynamically determined by the intelligent control unit based on the volatile fatty acid concentration of the effluent from the hydrolysis acidification unit and the nitrate load of the anoxic denitrification zone.

[0015] Preferably, the reuse buffer unit includes a low-water-level storage area and a high-water-level storage area. The low-water-level storage area receives the terminal effluent from the multi-stage ecological purification unit and allows it to settle. The high-water-level storage area stores the supernatant after settling. The reuse buffer unit preferentially draws water from the high-water-level storage area for its recirculation operation. When the water level in the high-water-level storage area is lower than a set threshold, the intelligent control unit reduces the recirculation ratio and increases the internal circulation flow of the multi-stage ecological purification unit to delay the reuse of effluent and maintain the hydraulic balance of the system.

[0016] Preferably, when the source separation unit separates based on density differences, the intelligent control unit adjusts the separation cutting particle size according to the solid content and temperature of the raw fecal liquid, so that the suspended solids concentration of the low-concentration liquid phase after separation is controlled within a preset range; and the high-concentration solid phase separated by the source separation unit is guided to the external solid phase treatment module, while the low-concentration liquid phase enters the hydrolysis acidification unit to avoid carbon source loss caused by the sideflow of the liquid phase.

[0017] Preferably, the intelligent control unit has a built-in water quality response model. The water quality response model uses the chemical oxygen demand, ammonia nitrogen, and volatile fatty acid concentrations of the effluent from the hydrolysis acidification unit as input variables, and the dissolved oxygen setpoint, internal circulation reflux ratio, and recirculation ratio of the reuse buffer unit in each zone of the multi-stage ecological purification unit as output variables. The model performs feedforward-feedback composite adjustment of the output variables by updating parameters in real time, so that the system maintains a stable removal rate of total nitrogen and total phosphorus in the effluent when the influent water quality fluctuates.

[0018] Preferably, the system further includes a seasonal operation mode switching logic. The intelligent control unit increases the internal circulation flow of the multi-stage ecological purification unit and shortens the actual hydraulic retention time of the plant absorption zone in low-temperature mode, based on the ambient temperature and the growth cycle of aquatic plants. At the same time, it decreases the internal circulation flow and extends the actual hydraulic retention time of the plant absorption zone in high-temperature mode. The switching logic also adjusts the temperature maintenance strategy of the hydrolysis acidification unit to ensure that the yield of volatile fatty acids in different modes matches the carbon source demand of the anoxic denitrification zone.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. This invention discloses an ecological treatment system for liquid manure from livestock and poultry farms. Through a water quality response model built into the intelligent control unit, it establishes a feedforward-feedback composite correlation between the effluent water quality parameters of the hydrolysis and acidification unit and the operating parameters of the multi-stage ecological purification unit, achieving global coordinated control among all units of the system. Compared to the independent operation mode of existing technologies, this invention significantly improves the system's adaptive capability to fluctuations in influent load.

[0021] 2. This invention provides an ecological treatment system for liquid manure from livestock and poultry farms. By incorporating a gas-liquid isolation baffle structure within a multi-stage ecological purification unit, the system physically ensures the dissolved oxygen gradient between the anoxic and aerobic zones. Simultaneously, dynamic adjustment through internal circulation reflux achieves precise carbon source allocation. Volatile fatty acids generated by the hydrolysis and acidification unit are utilized in situ as a carbon source for denitrification, eliminating the need for external carbon source addition and reducing operating costs.

[0022] 3. The present invention provides an ecological treatment system for liquid manure from livestock and poultry farms. By linking the reuse buffer unit with the front-end treatment unit through signal transmission, a mechanism for adjusting the water supply ratio based on the water level of the high-level storage area is established. When the reuse water volume is insufficient, the system automatically increases the internal circulation flow to maintain hydraulic balance, achieving coordinated matching between effluent reuse and treatment load, and avoiding the problem of disconnect between reuse strategy and treatment operation in traditional systems.

[0023] 4. The present invention provides an ecological treatment system for liquid manure from livestock and poultry farms. Through a seasonal operation mode switching logic, the system maintains stable treatment efficiency under different ambient temperatures and aquatic plant growth cycles, solving the common industry problem of significant decline in treatment efficiency of traditional constructed wetlands under low-temperature conditions in winter. Attached Figure Description

[0024] Figure 1 This is a general process flow diagram of an ecological treatment system for liquid manure from livestock and poultry farms according to the present invention;

[0025] Figure 2 This is a schematic diagram of the partitioned structure and internal circulation flow of the multi-level ecological purification unit in this invention;

[0026] Figure 3 This is a schematic diagram of the signal connection and data flow of the intelligent control unit in this invention;

[0027] Figure 4 This is a schematic diagram of the water level partitioning and feedback scheduling logic of the reuse buffer unit in this invention. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals.

[0029] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0030] To make the content of this invention easier to understand, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings.

[0031] like Figures 1 to 4 As shown, this invention discloses an ecological treatment system for liquid manure from livestock and poultry farms. Its core technological architecture comprises source separation, hydrolysis acidification, multi-stage ecological purification, and intelligent control. The system has a rational structure, with highly modular units, facilitating engineering implementation and operation and maintenance management. This system can be widely applied to the treatment of liquid manure from large-scale pig farms, dairy farms, chicken farms, and other livestock and poultry farms, possessing significant promotional value and industrialization prospects. All core equipment in the system can be domestically produced, ensuring controllable construction and operating costs, making it suitable for large-scale application.

[0032] Example 1

[0033] This embodiment provides an ecological treatment system for liquid manure from livestock and poultry farms, the overall process flow of which is as follows: Figure 1As shown, the treatment object is the mixed liquid of manure and sludge produced by a large-scale pig farm with 5,000 pigs, which produces about 80 tons of liquid manure and sludge per day.

[0034] The source separation unit is configured to receive raw sewage and separate it into a high-concentration solid phase and a low-concentration liquid phase based on density differences. In this embodiment, the source separation unit employs a screw extrusion density separation device, utilizing the density difference between solid particles and liquid in a centrifugal force field to achieve separation. The feed inlet of the source separation unit is connected to the sewage collection tank, and the raw sewage is fed into the separation chamber at an appropriate pressure by a feed pump.

[0035] The intelligent control unit adjusts the separation and cutting particle size in real time based on the solid content and temperature of the raw sewage solution. In this embodiment, the solid content is monitored by an online turbidimeter, and the temperature is monitored by an insertion temperature sensor. When the solid content of the raw solution is high, the intelligent control unit reduces the rotation speed of the screw extrusion and increases the effective separation area of ​​the separation chamber to reduce the cutting particle size, ensuring that the concentration of suspended solids in the low-concentration liquid phase after separation is controlled within a reasonable range. When the temperature of the raw solution is low, the intelligent control unit also reduces the cutting particle size to compensate for the decrease in separation efficiency caused by the increased liquid viscosity under low-temperature conditions.

[0036] The high-concentration solid phase separated by the source separation unit is directed to the external solid phase treatment module for composting or anaerobic dry fermentation; the low-concentration liquid phase enters the hydrolysis acidification unit entirely, with no liquid phase sideflow throughout the process, ensuring that the soluble organic carbon in the manure is not lost.

[0037] The hydrolysis acidification unit is connected to the liquid phase outlet of the source separation unit and is used for anoxic hydrolysis of the low-concentration liquid phase. The hydrolysis acidification unit is a plug-flow hydrolysis acidification tank, and a submersible agitator is installed in the tank to maintain an anoxic environment.

[0038] During the hydrolysis-acidification process, organic macromolecules such as proteins, polysaccharides, and fats are broken down into volatile fatty acids, mainly acetic acid, propionic acid, and butyric acid, by facultative hydrolytic bacteria. Simultaneously, bound ammonia nitrogen from protein molecules is released into the liquid phase. The goal of this process is to ensure that the concentration of volatile fatty acids in the effluent from the hydrolysis-acidification unit reaches a suitable range, providing a sufficient carbon source for the subsequent anoxic denitrification zone.

[0039] The effluent from the hydrolysis and acidification unit enters an intermediate equalization tank. This tank is equipped with a dosing device and an online pH monitor to adjust the effluent pH value, maintaining it within a suitable range to meet the metabolic requirements of subsequent denitrifying bacteria. Simultaneously, the intermediate equalization tank contains a stirring device to homogenize the hydrolysis and acidification effluent, reducing batch-to-batch fluctuations in effluent quality.

[0040] The effluent from the intermediate equalization tank is intermittently pumped to the anoxic denitrification zone of the multi-stage ecological purification unit in a pulsed manner. The period and amplitude of the pulses are dynamically determined by the intelligent control unit based on the volatile fatty acid concentration in the effluent from the hydrolysis acidification unit and the nitrate load in the anoxic denitrification zone. When the volatile fatty acid concentration and nitrate load are both high, the pulse period is shortened and the amplitude is increased; when the volatile fatty acid concentration and nitrate load are both low, the pulse period is lengthened and the amplitude is decreased. This pulsed influent helps to create periodic fluctuations in carbon source concentration within the anoxic denitrification zone, promoting the alternating activity of denitrifying bacteria and improving carbon source utilization efficiency.

[0041] The multi-stage ecological purification unit, along the liquid flow direction, includes a primary anoxic denitrification zone, a primary aerobic nitrification zone, and a primary plant absorption zone. Its zoning structure and internal circulation flow direction are as follows: Figure 2 As shown.

[0042] The bottom of the anoxic denitrification zone is lined with volcanic rock packing material, and the surface of the packing material is covered with a biofilm of denitrifying bacteria. The anoxic denitrification zone receives pulsed effluent from the intermediate equalization tank and uses volatile fatty acids produced by the hydrolysis acidification unit as a carbon source for denitrification, reducing nitrate nitrogen to nitrogen gas.

[0043] A gas-liquid isolation baffle structure is installed between the anoxic denitrification zone and the aerobic nitrification zone. This baffle structure consists of vertical baffles and horizontal guide plates. The lower end of the vertical baffle is submerged to an appropriate depth below the liquid surface, while the upper end extends above the liquid surface. The horizontal guide plates extend from the bottom of the vertical baffles towards the aerobic nitrification zone. This structure allows the dissolved oxygen generated in the aerobic nitrification zone to be consumed by the resistance of the baffles during the liquid-phase mass transfer process. At the same time, the rising nitrogen bubbles generated in the anoxic denitrification zone are intercepted at the baffles, further preventing the diffusion of dissolved oxygen into the anoxic zone and maintaining the anaerobic environment of the anoxic denitrification zone.

[0044] The bottom of the aerobic nitrification zone is equipped with microporous aeration discs, supplied with air by a Roots blower. Suspended activated sludge is maintained at a certain concentration within the aerobic nitrification zone, and dissolved oxygen is controlled within an appropriate range by an intelligent control unit. Under aerobic conditions, ammonia nitrogen is converted to nitrate nitrogen by ammonia-oxidizing bacteria and nitrite-oxidizing bacteria.

[0045] A portion of the nitrified liquor from the aerobic nitrification zone is returned to the inlet of the anoxic denitrification zone via an internal circulation pipeline. This return flow rate is adjusted in real-time by an intelligent control unit based on the carbon-to-nitrogen ratio (C / N ratio) of the anoxic denitrification zone. The internal circulation pipeline is equipped with an electromagnetic flow meter and an electric regulating valve, allowing for continuous adjustment of the return ratio within a wide range. The intelligent control unit calculates the C / N ratio in real-time using online nitrate and COD sensors at the outlet of the anoxic denitrification zone. When the C / N ratio is low, the return ratio is increased to dilute the nitrate concentration entering the anoxic zone, thereby improving the denitrification efficiency per unit carbon source. When the C / N ratio is high, the return ratio is decreased to reduce the hydraulic load. Through this dynamic adjustment, the C / N ratio of the anoxic denitrification zone is maintained within a suitable range.

[0046] The plant absorption zone is divided into a shallow root zone and a deep floating bed zone along the flow direction. The shallow root zone is planted with emergent plants such as reeds and cattails, resulting in a shorter hydraulic retention time. The deep floating bed zone has a greater depth and is planted with floating plants such as water hyacinth and duckweed, with the coverage controlled within an appropriate range, resulting in a longer hydraulic retention time. The effluent from the shallow root zone enters the deep floating bed zone through a drop weir. The drop weir reoxygenates the water, increasing the dissolved oxygen concentration in the deep floating bed zone and enhancing its nitrification-assisted effect, allowing residual ammonia nitrogen to be further oxidized and removed in the plant absorption zone.

[0047] The reuse buffer unit connects to the terminal outlet of the multi-stage ecological purification unit, and its structure is as follows: Figure 4 As shown, it includes a low-water storage area and a high-water storage area. The low-water storage area receives the effluent from the multi-stage ecological purification unit and allows it to settle. A small amount of suspended solids at the bottom are periodically discharged through the sludge discharge pipe. The supernatant after settling flows by gravity into the high-water storage area, which is used to store the purified effluent and supply it back to the source separation unit or external flushing pipeline according to the plant's water demand.

[0048] The reuse buffer unit prioritizes drawing water from the high-level storage area, with the intake located at an appropriate depth below the water surface to avoid surface scum and bottom sediment. An ultrasonic level gauge is installed in the high-level storage area to monitor water level changes in real time. When the water level in the high-level storage area falls below a set threshold, the intelligent control unit reduces the reuse ratio and increases the internal circulation flow of the multi-stage ecological purification unit to delay effluent reuse and maintain the system's hydraulic balance.

[0049] The intelligent control unit is connected to the source separation unit, hydrolysis acidification unit, multi-stage ecological purification unit, and reuse buffer unit via signals, and their signal connections and data flow are as follows: Figure 3 As shown.

[0050] The core of the intelligent control unit is an industrial-grade embedded controller with a built-in water quality response model. This model uses the chemical oxygen demand, ammonia nitrogen, and volatile fatty acid concentrations of the effluent from the hydrolysis acidification unit as input variables, and the dissolved oxygen setpoints, internal circulation reflux ratios, and recirculation ratios of the reuse buffer unit in each zone of the multi-stage ecological purification unit as output variables.

[0051] The water quality response model adopts a feedforward-feedback composite regulation architecture: the feedforward part makes predictive adjustments based on the real-time detection value of the influent water quality. When the chemical oxygen demand of the effluent from the hydrolysis acidification unit suddenly increases, the model increases the dissolved oxygen setpoint and internal circulation reflux ratio in advance to reserve buffer capacity for subsequent treatment units. The feedback part makes corrections based on the actual operating effect of each zone of the multi-stage ecological purification unit. When the nitrate concentration at the outlet of the anoxic denitrification zone is higher than the preset value, the model further adjusts the reflux ratio and pulse influent parameters.

[0052] The parameters of the water quality response model are updated periodically, and the model gain coefficient is corrected online using the recursive least squares method to maintain the model's ability to track the time-varying characteristics of the system. Through this combined regulation mechanism, the system can maintain a stable removal rate of total nitrogen and total phosphorus in the effluent even under fluctuating influent water quality conditions.

[0053] Overall system workflow and performance

[0054] The overall workflow of the system in this embodiment is as follows: The raw manure liquid first enters the source separation unit for density separation. The high-concentration solid phase is transported for composting, while the low-concentration liquid phase enters the hydrolysis and acidification unit for facultative hydrolysis. The hydrolysis and acidification effluent, after conditioning in an intermediate equalization tank, enters the multi-stage ecological purification unit in a pulsed manner, sequentially passing through the anoxic denitrification zone for nitrogen removal, the aerobic nitrification zone for nitrification, and the plant absorption zone for deep purification. The purified effluent enters the reuse buffer unit, preferentially reused for plant area flushing and dilution water from the source separation unit; the excess is discharged after meeting standards. The intelligent control unit monitors and coordinates the key parameters of each unit in real time throughout the process.

[0055] Monitoring data from six months of continuous operation of the system showed that the influent chemical oxygen demand (COD), ammonia nitrogen, total nitrogen (TNO), and total phosphorus (TP) were all at high concentrations; the effluent COD remained stable at a low level, while ammonia nitrogen, TNO, and TTP all met the limits set by the "Emission Standard for Pollutants from Livestock and Poultry Farming". The system's daily recycled water consumption accounts for over 60% of the total treated effluent, significantly reducing the amount of fresh water required. Compared to existing technologies, this system requires no external carbon source, significantly reducing treatment costs and noticeably improving operational stability.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 is that the treatment object is a dairy farm with 2,000 cows, producing approximately 45 tons of liquid manure per day. Due to the high cellulose content in the dairy farm manure, the hydraulic retention time of the hydrolysis and acidification unit is extended to fully break down large cellulose molecules. The water quality response model parameters of the intelligent control unit have been adjusted to suit the characteristics of the dairy farm manure, and cellulase activity has been added as an auxiliary correction parameter to the model input variables.

[0058] In the plant absorption zone of the multi-level ecological purification unit, calamus and canna lilies are planted in the shallow water root zone to replace reeds and cattails, in order to adapt to the higher potassium ion concentration in the dairy farm effluent. In the seasonal operation mode switching logic, the start-up temperature threshold of the low-temperature mode is set to a lower value to adapt to the higher sensitivity of the dairy farm manure treatment system to low temperatures. The remaining structure and working principle are the same as in Example 1, and the operation effect is good.

[0059] Example 3

[0060] The difference between this embodiment and Embodiment 1 is that the system adds a seasonal operation mode switching logic. The intelligent control unit automatically switches the operation mode according to the ambient temperature and the growth cycle of aquatic plants.

[0061] In low-temperature mode, the intelligent control unit increases the internal circulation flow rate of the multi-stage ecological purification unit from the standard mode, while simultaneously shortening the actual hydraulic retention time in the plant absorption zone. Increasing the internal circulation flow rate helps to enhance heat exchange within the system, mitigating the inhibitory effect of low temperatures on microbial activity; shortening the hydraulic retention time in the plant absorption zone prevents excessive cooling and stagnation of the effluent under low-temperature conditions. Simultaneously, the heating device of the hydrolysis acidification unit is activated to maintain the tank temperature within an appropriate range, ensuring that the yield of volatile fatty acids is not lower than the higher level observed in the ambient temperature mode.

[0062] In high-temperature mode, the intelligent control unit reduces the internal circulation flow while extending the actual hydraulic retention time in the plant absorption zone. Extending the hydraulic retention time fully utilizes the vigorous metabolic activity of plants and microorganisms under high-temperature conditions, further improving effluent quality. The heating device of the hydrolysis and acidification unit is shut off, relying on ambient temperature to maintain the hydrolysis and acidification process. Through seasonal operation mode switching logic, the system ensures stable effluent quality throughout the year, with a significantly higher total nitrogen removal rate in winter compared to traditional fixed-mode systems.

[0063] The remaining structure and working principle are the same as in Example 1.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ecological treatment system for liquid waste from livestock and poultry farms, characterized in that, include: The source separation unit is configured to receive raw fecal waste liquid and separate it into a high-concentration solid phase and a low-concentration liquid phase based on density differences. The hydrolysis acidification unit is connected to the liquid phase outlet of the source separation unit and is used to perform anoxic hydrolysis on the low-concentration liquid phase to break down organic macromolecules into volatile fatty acids and simultaneously release bound ammonia nitrogen. The multi-stage ecological purification unit includes, in sequence along the liquid flow direction, at least one anoxic denitrification zone, at least one aerobic nitrification zone, and at least one plant absorption zone. The anoxic denitrification zone receives the effluent from the hydrolysis acidification unit and uses the volatile fatty acids as a carbon source for denitrification. The aerobic nitrification zone treats the denitrification effluent with nitrification. The plant absorption zone uses the roots of aquatic plants to absorb residual nutrients. A reuse buffer unit is connected to the end outlet of the multi-stage ecological purification unit to temporarily store the purified water and supply it back to the source separation unit or external flushing pipeline according to the water demand of the plant area. The intelligent control unit is connected to the source separation unit, the hydrolysis acidification unit, the multi-stage ecological purification unit, and the reuse buffer unit. The intelligent control unit dynamically adjusts the flow ratio of the source separation unit, the internal circulation flow rate of the multi-stage ecological purification unit, and the return supply ratio of the reuse buffer unit based on the effluent water quality parameters of the hydrolysis acidification unit and the dissolved oxygen and oxidation-reduction potential of each zone of the multi-stage ecological purification unit.

2. The ecological treatment system for liquid manure from livestock and poultry farms according to claim 1, characterized in that, In the multi-stage ecological purification unit, a gas-liquid isolation baffle structure is provided between the at least one-stage anoxic denitrification zone and the at least one-stage aerobic nitrification zone. The gas-liquid isolation baffle structure causes the dissolved oxygen generated in the nitrification zone to be consumed during the liquid phase mass transfer process, so as to maintain the anaerobic environment of the anoxic denitrification zone. At the same time, part of the nitrified liquid in the aerobic nitrification zone is returned to the inlet of the anoxic denitrification zone through an internal circulation pipe. The return flow rate is adjusted in real time by the intelligent control unit according to the carbon-nitrogen ratio of the anoxic denitrification zone.

3. The ecological treatment system for liquid manure from livestock and poultry farms according to claim 1, characterized in that, The plant absorption zone is divided into a shallow root zone and a deep floating bed zone along the liquid flow direction. The shallow root zone is planted with emergent plants and has a first hydraulic residence time, while the deep floating bed zone is planted with floating plants and has a second hydraulic residence time. The first hydraulic residence time is shorter than the second hydraulic residence time. The effluent from the shallow root zone enters the deep floating bed zone through a drop weir to enhance the nitrification assistance effect of the deep floating bed zone by utilizing the drop weir for reoxygenation.

4. The ecological treatment system for liquid manure from livestock and poultry farms according to claim 1, characterized in that, An intermediate regulating tank is provided between the hydrolysis acidification unit and the multi-stage ecological purification unit. The intermediate regulating tank receives the effluent from the hydrolysis acidification unit and adjusts its pH and alkalinity. The adjusted effluent is intermittently transported to the anoxic denitrification zone in a pulse manner. The period and amplitude of the pulse are dynamically determined by the intelligent control unit based on the volatile fatty acid concentration of the effluent from the hydrolysis acidification unit and the nitrate load of the anoxic denitrification zone.

5. The ecological treatment system for liquid manure from livestock and poultry farms according to claim 1, characterized in that, The reuse buffer unit includes a low-water-level storage area and a high-water-level storage area. The low-water-level storage area receives the terminal effluent from the multi-stage ecological purification unit and allows it to settle. The high-water-level storage area stores the supernatant after settling. The reuse buffer unit preferentially draws water from the high-water-level storage area for its recirculation operation. When the water level in the high-water-level storage area is lower than a set threshold, the intelligent control unit reduces the recirculation ratio and increases the internal circulation flow of the multi-stage ecological purification unit to delay the reuse of effluent and maintain the hydraulic balance of the system.

6. The ecological treatment system for liquid manure from livestock and poultry farms according to claim 1, characterized in that, When the source separation unit separates based on density differences, the intelligent control unit adjusts the separation cutting particle size according to the solid content and temperature of the raw fecal liquid, so that the suspended solids concentration of the low-concentration liquid phase after separation is controlled within a preset range. Furthermore, the high-concentration solid phase separated by the source separation unit is guided to the external solid phase treatment module, while the low-concentration liquid phase enters the hydrolysis acidification unit to avoid carbon source loss caused by the sideflow of the liquid phase.

7. The ecological treatment system for liquid manure from livestock and poultry farms according to claim 1, characterized in that, The intelligent control unit has a built-in water quality response model. The water quality response model uses the chemical oxygen demand, ammonia nitrogen, and volatile fatty acid concentrations of the effluent from the hydrolysis acidification unit as input variables, and the dissolved oxygen setpoint, internal circulation reflux ratio, and recirculation ratio of the reuse buffer unit as output variables. The model performs feedforward-feedback composite adjustment of the output variables by updating parameters in real time, so that the system maintains a stable removal rate of total nitrogen and total phosphorus in the effluent when the influent water quality fluctuates.

8. The ecological treatment system for liquid manure from livestock and poultry farms according to any one of claims 1 to 7, characterized in that, The system also includes a seasonal operation mode switching logic. The intelligent control unit increases the internal circulation flow of the multi-stage ecological purification unit and shortens the actual hydraulic residence time of the plant absorption zone in low-temperature mode, based on the ambient temperature and the growth cycle of aquatic plants. At the same time, it decreases the internal circulation flow and extends the actual hydraulic residence time of the plant absorption zone in high-temperature mode. The switching logic also adjusts the temperature maintenance strategy of the hydrolysis acidification unit to ensure that the yield of volatile fatty acids in different modes matches the carbon source demand of the anoxic denitrification zone.

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