A movable photovoltaic power supply subcritical fertilizer production system and product application for nitrogen and phosphorus emission reduction and efficiency increase and high-moisture waste resource disposal

Abstract

This invention belongs to the field of biomass subcritical fertilizer production, specifically relating to a mobile photovoltaic-powered subcritical fertilizer production system and its product application aimed at reducing nitrogen and phosphorus emissions, increasing efficiency, and resource-based disposal of high-moisture waste. It includes a solar preheating system, a photovoltaic power supply system, an auxiliary heating system, a hydrothermal reaction system, and a post-treatment system. The photovoltaic power supply system and auxiliary heating system are connected to the electrical load of the hydrothermal reaction system; the hydrothermal reaction system is connected to both the solar preheating system and the post-treatment system. This invention utilizes electrodialysis technology to desalinate the hydrothermal charcoal before returning it to the field. Through electrodialysis, the desalination rate of the charcoal reaches 45%-90%, and the conductivity of the desalinated charcoal is 1.40-6.75 mS / cm. The desalinated charcoal significantly increases crop yield; chlorophyll content increases by 25.5-67.5%, fresh weight increases by 18.5%-175%, and lettuce root length increases by 37.0%-98.2%. The high degree of desalination avoids the negative effects of salt stress on lettuce roots.

Description

Technical Field

[0001] This invention belongs to the field of biomass subcritical fertilizer production, specifically involving a mobile photovoltaic-powered subcritical fertilizer production system and its product application for nitrogen and phosphorus emission reduction and efficiency improvement and resource utilization of high-moisture waste. Background Technology

[0002] Nutrient losses such as nitrogen and phosphorus during agricultural production are a major source of nutrient surplus in farmland, aquatic, and wetland ecosystems, and a significant cause of non-point source pollution. Hydrothermal carbonization (HTC) is a novel material conversion process that can convert high-moisture raw materials into hydrothermal carbon and charcoal liquid in a short time under relatively low temperature (<250℃) and energy input conditions. The hydrothermal carbon can be used as fuel, soil conditioner, and a novel carbon material, while the charcoal liquid contains abundant nutrients and is rich in amino acids, making it suitable as a liquid fertilizer. Both have economic value. This technology has attracted widespread international attention, providing a new solution for waste treatment and resource recycling. However, most existing hydrothermal reaction equipment still uses traditional electric heating or boiler hot water heating, consuming large amounts of non-renewable energy. High reaction energy consumption and high operation and maintenance costs severely restrict the progress and widespread application of hydrothermal carbonization technology in large-scale production. Therefore, to promote further research on hydrothermal carbonization technology, the development of low-energy-consumption, low-operation-cost, and sustainable hydrothermal carbonization equipment is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a mobile photovoltaic-powered subcritical fertilizer production system and its application for nitrogen and phosphorus emission reduction and efficiency improvement, as well as resource utilization of high-moisture waste.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a mobile photovoltaic-powered subcritical fertilizer production system for nitrogen and phosphorus emission reduction and efficiency improvement and resource utilization of high-moisture waste, comprising a solar preheating system, a photovoltaic power supply system, an auxiliary heating system, a hydrothermal reaction system, and a post-treatment system; the photovoltaic power supply system and the auxiliary heating system are connected to the electrical load of the hydrothermal reaction system; the hydrothermal reaction system is connected to the solar preheating system and the post-treatment system respectively;

[0005] The solar preheating system includes a heat pipe solar collector, a solar water tank, a PLC controller, a water pump, and a shut-off valve; one side of the solar water tank is connected to the hydrothermal reaction system via the water pump and the shut-off valve, and the other side is connected to the PLC controller via a pipeline; the solar water tank and the heat pipe solar collector are connected in parallel and fixed by a bracket;

[0006] The photovoltaic power supply system includes photovoltaic modules, a photovoltaic controller, a battery bank, an inverter, and a distribution box; the output terminal of the photovoltaic module is connected to the input terminal of the photovoltaic controller; the output terminal of the photovoltaic controller is connected to the input terminal of the battery bank; the output terminal of the battery bank is connected to the input terminal of the inverter; the output terminal of the inverter is connected to the input terminal of the distribution box; and the output terminal of the distribution box is connected to the electrical load of the hydrothermal reaction system.

[0007] The auxiliary heating system includes an auxiliary heater; the output end of the auxiliary heater is connected to the electrical load of the hydrothermal reaction system.

[0008] The hydrothermal reaction system includes a feeder, a reactor, a filter press, a solid storage device, and a liquid storage device; the feeder is connected to the feed inlet of the reactor; the discharge outlet of the reactor is connected to the filter press; the filter press is connected to both the solid storage device and the liquid storage device; and the liquid storage device is connected to the electrodialysis device.

[0009] The post-processing system includes an electrodialysis unit; the inlet of the electrodialysis unit is connected to the outlet of the liquid storage unit.

[0010] The solar water tank in the solar preheating system is connected to the heat pipe solar collector. The inner wall of the heat pipe solar collector is equipped with a temperature sensor, which is connected to the PLC controller.

[0011] The bottom of the heat pipe solar collector is fixed by a bracket;

[0012] The solar water tank has an inlet at one end and an outlet at the other end, and is equipped with a shut-off valve.

[0013] The photovoltaic power supply system consists of at least one set of photovoltaic modules, and is equipped with a base.

[0014] The battery pack in the photovoltaic power supply system contains at least two batteries, which are connected in series.

[0015] The feeder has a sample inlet at the top and a sample outlet on the side, and the sample outlet of the feeder is connected to the feed inlet of the reactor.

[0016] The reaction vessel includes a motor and a stirrer;

[0017] The filter press is connected to the outlet of the reactor and is equipped with a water pump and a shut-off valve.

[0018] The outlet of the filter press is connected to both a solid storage device and a liquid storage device;

[0019] The product storage devices used in the hydrothermal reaction stage include solid storage devices and liquid storage devices.

[0020] The outlet of the liquid storage device is connected to the inlet of the electrodialysis device via a pipeline.

[0021] This invention also discloses the application of a mobile photovoltaic-powered subcritical fertilizer production system for nitrogen and phosphorus emission reduction and efficiency improvement, as well as resource utilization of high-moisture waste, comprising the following steps:

[0022] In the solar water tank, the water required for the hydrothermal carbonization reaction is preheated. This process is monitored and controlled by a PLC controller. After the water is heated, it is transported to the reaction vessel through a water pump and a shut-off valve.

[0023] The hydrothermal carbonization reaction feedstock is added through the inlet of the feeder and then transported to the feed inlet of the reactor through the outlet of the feeder. The feedstock for hydrothermal carbonization is manure or vegetable waste. The reaction temperature is 180-260℃, and the reaction time is 0.8-1.2h. The mass-to-volume ratio of manure or vegetable waste to water in the hydrothermal carbonization reaction is 1kg:9-11L. The manure is cow dung or pig dung. The agitator in the reactor rotates at 200-300r / min and is used to stir the feedstock during the hydrothermal carbonization process. The reactor is completely sealed during the hydrothermal carbonization process, and the internal pressure of the reactor is 1.0-1.8MPa. After the reaction is completed, the reactor is cooled. After the reactor is depressurized, it can be opened to discharge the product. The product is fed from the discharge port of the reactor into a filter press through a water pump and a shut-off valve. Solid-liquid separation of the product is carried out by the filter press method, so that the water content of the hydrothermal carbon is less than 30%. The hydrothermal carbon is stored in a solid storage device, and the carbon liquid is stored in a liquid storage device.

[0024] The char liquid enters the electrodialysis device from the liquid storage device and is subjected to electrodialysis under the conditions of DC voltage 25-35V and peristaltic pump 40-80RPM. The desalination rate is 45%-90%, which is the mass fraction. The electrodialysis time is 15-120min (preferably 45-90min), and a desalinated char liquid with a conductivity of 1.40-6.75mS / cm is obtained. By adopting the above electrodialysis operating parameters, the desalination rate is improved. The carbon liquid contains almost no colloids, making it suitable for membrane technology desalination. Furthermore, a reasonable electrodialysis time can reduce the pollution of ion exchange membranes by dissolved organic matter such as humic acid and fulvic acid in the hydrothermal carbon liquid. Other desalination methods, such as reverse osmosis and ultrafiltration, mainly aim to obtain fresh water and achieve water recycling. However, the purpose of HAP desalination in this invention is to remove inorganic salt ions, such as sodium chloride, and separate them from the liquid phase, while retaining organic matter such as humic acid and some nutrients in the liquid phase. The desalinated HAP can still be used as liquid organic fertilizer or soil conditioner. Other desalination technologies cannot achieve similar results.

[0025] Taking a single reaction processing capacity of 30-50L of raw material as an example, after pretreatment, the raw material is heated for 3-4 hours using a preheating system, followed by a hydrothermal reaction for 1-2 hours. After the reaction is complete and the power is cut off, the material is allowed to cool and depressurize naturally at room temperature, which takes approximately 12 hours. A single reaction takes about one day.

[0026] Preferably, the desalination rate of the carbon liquid is 80%-90%, resulting in a desalinated carbon liquid with an electrical conductivity of 1.40±0.15 mS / cm.

[0027] Desalinated carbon solution is applied as a fertilizer to the soil for plant growth. The nitrogen replacement rate of the desalinated carbon solution is 24%-40%, expressed as a mass fraction. For fast-growing plants, the desalinated carbon solution is applied twice: the first time during the seedling stage and the second time during the mid-to-late stages of plant growth, with a mass ratio of 2:2.5-3.5 between the first and second applications. For wheat, the desalinated carbon solution is applied three times, with roughly equal amounts applied at the basal, tillering, and heading stages. By adding it in stages at different fertilization periods, the carbon solution works at different stages of plant growth. Applying the entire solution at once can result in excessive concentration or dosage, potentially causing seedling burn.

[0028] Hydrothermal charcoal can also be applied as a fertilizer to the soil for plant growth. The nitrogen replacement rate of hydrothermal charcoal is 15%-25%, and the phosphorus replacement rate is 25%-35%, with percentages representing mass fractions. This hydrothermal charcoal is manure-derived. The application rate of hydrothermal charcoal is approximately the same at the basal fertilizer, tillering fertilizer, and heading fertilizer stages. When applying, the hydrothermal charcoal should be thoroughly mixed with the top 0-20cm of soil. The application rate of hydrothermal charcoal is 0.2-2% of the topsoil, with percentages representing mass fractions.

[0029] When desalinated carbon liquid is applied as fertilizer to the soil for plant growth, it increases the chlorophyll content of plant leaves, promotes the accumulation of plant biomass, and increases the root length of plants.

[0030] The advantages of this invention are:

[0031] Direct application of hydrothermal carbonization liquid products to farmland can accelerate soil salinization due to high salt content, and the high concentration of nutrients such as ammonia nitrogen is detrimental to plant growth, while also causing ammonia volatilization. This invention utilizes electrodialysis technology to desalinate the hydrothermal carbonized liquid before returning it to the field. Electrodialysis improves desalination efficiency, and the highly desalinated carbonized liquid significantly increases crop yields, especially greatly promoting plant root growth.

[0032] The post-processing system used in this invention can effectively remove salt from the liquid-phase product carbon liquid, reduce potential environmental pollution, and improve the safety of the product for agricultural or other applications.

[0033] The solar preheating system used in this invention can preheat the water required by the hydrothermal reaction system to a certain temperature (90℃ in summer and 50℃ in winter), directly converting a portion of solar energy into heat energy and reducing energy loss. Taking a hydrothermal reaction system temperature of 180℃ as an example, it can reduce the energy consumption of the heating process by about 27% to 50%.

[0034] The photovoltaic power supply system used in this invention is equipped with photovoltaic modules, which can effectively store light energy and generate electricity to drive the hydrothermal reaction system, thereby significantly reducing the energy consumption of the processing system.

[0035] The hydrothermal reaction system used in this invention has strong equipment sealing and no secondary pollution during the reaction process. It can efficiently convert raw materials with high water content (such as vegetable waste, livestock and poultry manure, etc.) into hydrothermal char and char liquid with certain economic and ecological benefits, achieving a 90% reduction in the mass and a 60% reduction in the volume of the reaction raw materials, and promoting the recycling of resources.

[0036] The auxiliary heating system used in this invention can ensure the normal operation of the hydrothermal reaction system when photovoltaic power generation is insufficient, thereby improving the stability of the equipment. Attached Figure Description

[0037] Figure 1 A framework diagram of a mobile photovoltaic-powered subcritical fertilizer production system for nitrogen and phosphorus emission reduction and efficiency improvement, as well as resource utilization of high-moisture waste.

[0038] Figure 2 This is a schematic diagram of a mobile photovoltaic-powered subcritical fertilizer production system designed for nitrogen and phosphorus emission reduction and efficiency improvement, as well as resource utilization of high-moisture waste.

[0039] Figure 3 The effects of different manure and its hydrothermal carbon on the concentrations of (a) ammonium nitrogen and (b) nitrate nitrogen in paddy field surface water;

[0040] Figure 4 The effects of different manure and hydrothermal carbon treatments on phosphorus concentration in paddy field surface water;

[0041] Figure 5 The effects of different manure and its hydrothermal carbon on (a) N2O emission flux and (b) cumulative emissions in paddy field soil;

[0042] Figure 6 The effects of different manure and its hydrothermal carbon on (a) NH3 volatilization flux and (b) cumulative volatilization in paddy soil;

[0043] Figure 7 The effects of typical carbon liquid and desalination carbon liquid on the growth (biomass) of pak choi and lettuce were investigated. A, pak choi; B, lettuce.

[0044] Figure 8The effects of typical carbon liquid and desalination carbon liquid on the biomass and root growth of Chinese cabbage and lettuce were investigated. A. Chlorophyll content, B. Fresh weight of plants, C. Dry weight of plants, D. Root length of plants, E. Chinese cabbage root, F. Lettuce root.

[0045] Figure 9 Physiological indicators for wheat harvesting at the heading stage;

[0046] Figure 10 Physiological indicators of wheat roots harvested at the heading stage;

[0047] Figure 11 These are indicators of the yield and quality of wheat grains harvested at maturity.

[0048] In the diagram: 1-Photovoltaic module; 2-Photovoltaic controller; 3-Battery pack; 4-Inverter; 5-Distribution box; 6-Auxiliary heater; 7-PLC controller; 8-Solar water tank; 9-Heat pipe solar collector; 10-Water pump; 11-Stop valve; 12-Feeder; 13-Reaction vessel; 14-Filter press; 15-Solid storage device; 16-Liquid storage device; 17-Inlet; 18-Motor; 19-Agitator; 20-Outlet; 21-Electrodialysis device. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1 and Figure 2 As shown, this invention provides a mobile photovoltaic-powered subcritical fertilizer production system for nitrogen and phosphorus emission reduction and efficiency improvement, as well as resource utilization of high-moisture waste. The system includes a solar preheating system, a photovoltaic power supply system, an auxiliary heating system, a hydrothermal reaction system, and a post-treatment system. The photovoltaic power supply system and the auxiliary heating system are connected to the electrical load of the hydrothermal reaction system. The hydrothermal reaction system is tightly connected to the solar preheating system and the post-treatment system via pipelines. The system also includes a water pump 10, a shut-off valve 11, and other connecting devices.

[0051] The solar preheating system includes a heat pipe solar collector 9, a solar water tank 8, a PLC controller 7, a water pump 10, and a shut-off valve 11. One side of the solar water tank 8 is connected to the hydrothermal reaction system via the water pump 10 and the shut-off valve 11, and the other side is connected to the PLC controller 7 via a pipeline. The solar water tank 8 is connected in parallel with the heat pipe solar collector 9 and is fixed by a bracket.

[0052] The photovoltaic power supply system includes a photovoltaic module 1, a photovoltaic controller 2, a battery pack 3, an inverter 4, and a distribution box 5. The output terminal of the photovoltaic module 1 is connected to the input terminal of the photovoltaic controller 2. The output terminal of the photovoltaic controller 2 is connected to the input terminal of the battery pack 3. The output terminal of the battery pack 3 is connected to the input terminal of the inverter 4. The output terminal of the inverter 4 is connected to the input terminal of the distribution box 5. The output terminal of the distribution box 5 is connected to the electrical load of the hydrothermal reaction system and is equipped with an off-grid system.

[0053] The auxiliary heating system includes an auxiliary heater 6; the output end of the auxiliary heater 6 is connected to the electrical load of the hydrothermal reaction system.

[0054] The hydrothermal reaction system includes a feeder 12, a reactor 13, a filter press 14, a solid storage device 15, and a liquid storage device 16. The feeder 12 is connected to the inlet 17 of the reactor 13 via a pipeline. The outlet 20 of the reactor 13 is tightly connected to the filter press 14 via a pipeline. The system also includes a water pump 10, a shut-off valve 11, and other connecting devices. The filter press 14 is connected to the solid storage device 15 and the liquid storage device 16 via pipelines. The liquid storage device 16 is tightly connected to the electrodialysis device 21 via a pipeline.

[0055] The post-treatment system includes an electrodialysis unit 21; the inlet of the electrodialysis unit 21 and the outlet of the liquid storage device 16 are connected by a pipe. Electrodialysis technology utilizes the selective permeability of ion exchange membranes to selectively migrate anions and cations under the action of an applied DC electric field, thereby forming a concentrate chamber and a desalination chamber alternately within the compartments formed by the ion exchange membranes to achieve desalination.

[0056] The solar water tank 8 in the solar preheating system is connected to the heat pipe solar collector 9. The inner wall of the heat pipe solar collector 9 is equipped with a temperature sensor, which is connected to the PLC controller 7.

[0057] The bottom of the heat pipe solar collector 9 is fixed by a bracket;

[0058] The solar water tank 8 has an inlet at one end and an outlet at the other end, and is equipped with a shut-off valve.

[0059] The photovoltaic power supply system comprises at least one set of photovoltaic modules 1, and is equipped with a base.

[0060] The battery pack 3 in the photovoltaic power supply system contains at least two batteries, which are connected in series.

[0061] The feeder 12 has a sample inlet on top and a sample outlet on the side. The sample outlet of the feeder 12 is tightly connected to the feed inlet 17 of the reactor 13 through a pipe.

[0062] The reaction vessel 13 includes auxiliary devices such as a motor 18 and a stirrer 19;

[0063] The inlet of the filter press 14 is connected to the outlet 20 of the reaction vessel 13 via a pipeline, and is equipped with a water pump 10 and a shut-off valve 11 and other connecting devices.

[0064] The outlet of the filter press 14 is connected to the solid storage device 15 and the liquid storage device 16 via pipes;

[0065] The hydrothermal reaction stage includes a solid storage device 15 and a liquid storage device 16.

[0066] The outlet of the liquid storage device 16 is connected to the inlet of the electrodialysis device 21 via a pipeline.

[0067] like Figure 1 As shown, the production system of the present invention includes a solar preheating system, a photovoltaic power supply system, an auxiliary heating system, a hydrothermal reaction system, and a post-processing system. The photovoltaic power supply system and the auxiliary heating system are connected to the electrical load of the hydrothermal reaction system. The hydrothermal reaction system is tightly connected to the solar preheating system and the post-processing system by pipes.

[0068] The main function of the solar preheating system is to convert solar energy into heat energy through the heat pipe solar collector 9, preheating the water required for hydrothermal carbonization. The main function of the photovoltaic power supply system is to convert light energy into electrical energy through the photovoltaic modules 1, powering the hydrothermal reaction system. The main function of the auxiliary heating system is to power the hydrothermal reaction system to ensure normal operation of the equipment when photovoltaic power generation is insufficient. The main function of the hydrothermal reaction system is to carry out the hydrothermal carbonization reaction of the input raw materials, generating hydrothermal carbon and molten carbon. The main function of the post-treatment system is to desalinate the molten carbon using electrodialysis technology, reducing secondary pollution.

[0069] When performing a hydrothermal carbonization reaction using the production system described in this invention, the following steps are included:

[0070] First, the water required for the hydrothermal carbonization reaction is preheated in the solar water tank 8. This process is monitored and controlled by the PLC controller 7. After the temperature is raised, the water is transported to the reaction vessel 13 through the water pump 10 and the shut-off valve 11.

[0071] like Figure 2As shown, the photovoltaic power supply system mainly includes photovoltaic modules 1, photovoltaic controller 2, battery pack 3, inverter 4, and distribution box 5. The function of photovoltaic module 1 is to convert solar radiation energy into DC power and it is connected to photovoltaic controller 2 through wires. The function of photovoltaic controller 2 is to regulate and control the power generated by the solar cell module, charge the battery pack 3, and provide overcharge and over-discharge protection for the battery pack 3. In areas with large temperature differences, photovoltaic controller 2 has a temperature compensation function. The input terminal of photovoltaic controller 2 is connected to the output terminal of photovoltaic module 1 through wires, and the output terminal of photovoltaic controller 2 is connected to the input terminal of battery pack 3 through connecting cables.

[0072] Specifically, photovoltaic module 1 is at least one set, with a base, and can be installed in an open area or on a roof.

[0073] Specifically, the battery pack 3 contains at least two batteries connected in series, which are used to store energy to ensure the power supply to the load. The input terminal of the battery pack 3 is connected to the output terminal of the photovoltaic controller 2 via a connecting cable, and the output terminal of the battery pack 3 is connected to the input terminal of the inverter 4 via a connecting cable. The battery pack 3 can be installed inside a concrete structure.

[0074] Specifically, inverter 4 is the core component of the photovoltaic power supply system. Its function is to convert the direct current generated by the photovoltaic cell module into alternating current for use by the AC load. The input terminal of inverter 4 is connected to the output terminal of battery pack 3 through a connecting cable, and the output terminal of inverter 4 is connected to the input terminal of distribution box 5 through a wire.

[0075] Specifically, the function of distribution box 5 is as an isolating switch, equipped with surge protection devices, overvoltage protection, and overcurrent protection. When the battery power is insufficient, it automatically switches to grid power supply and disconnects the original power supply line. The contactor contacts inside distribution box 5 are connected to the output terminal of inverter 4 via wires. The output terminal of distribution box 5 is connected to the load electrical appliances of the hydrothermal reaction system. Distribution box 5 is located near the photovoltaic power supply system and the hydrothermal reaction system.

[0076] like Figure 2 As shown, the auxiliary heating system mainly includes an auxiliary heater 6, which is used to supply power to the hydrothermal reaction system when photovoltaic power generation is insufficient, ensuring the normal operation of the equipment.

[0077] Specifically, the output of the auxiliary heater 6 is connected to the load electrical appliance of the hydrothermal reaction system, and the auxiliary heater 6 is located near the hydrothermal reaction system.

[0078] like Figure 2 As shown, the hydrothermal reaction system includes, in sequence, a feeder 12, a reactor 13, a filter press 14, a solid storage device 15, and a liquid storage device 16, as well as a water pump 10 and a shut-off valve 11 connected to each device;

[0079] Specifically, the hydrothermal carbonization reaction feedstock is added through the inlet of feeder 12 and then transported through the outlet of feeder 12 to the feed port 17 of reactor 13;

[0080] Specifically, the reactor 13 is equipped with a motor 18 and a stirrer 19. The stirrer 19 rotates at a speed of 200-300 r / min and is used to stir the raw materials during the hydrothermal carbonization process to improve the reaction efficiency.

[0081] Specifically, the reactor 13 is completely sealed during the hydrothermal carbonization process, with an internal pressure of 1.0–1.8 MPa. After the reaction is completed, the reactor 13 can be cooled by either purging with condensate or by natural cooling. To ensure operational safety, the reactor 13 can be opened to discharge material after depressurization.

[0082] Specifically, the product is fed from the outlet 20 of the reactor 13 into the filter press 14 via the water pump 10 and the shut-off valve 11. The solid and liquid components of the product are separated by the filter press method, so that the water content of the hydrothermal carbon is less than 30%. The hydrothermal carbon is stored in the solid storage device 15, and the carbon liquid is stored in the liquid storage device 16.

[0083] like Figure 2 As shown, the post-treatment system mainly includes an electrodialysis device 21;

[0084] Specifically, the molten carbon enters the electrodialysis unit 21 from the liquid storage device 16, and the salt in the molten carbon is removed by electrodialysis, thereby improving the safety of molten carbon resource utilization.

[0085] In this embodiment of the invention, the thermal energy required for the hydrothermal carbonization reaction is provided by a solar preheating system and a photovoltaic power generation system. The solar preheating system converts solar energy into thermal energy to preheat the reaction water, reducing energy loss during the conversion between solar and electrical energy. The photovoltaic power generation system converts solar energy into electrical energy, exhibiting low energy consumption and strong resistance to load shocks. An auxiliary heating system is also included to ensure operational performance under special weather conditions such as winter or prolonged periods of overcast and rainy weather, demonstrating sustainable application prospects. A post-treatment system desalinates the product charcoal, effectively reducing its salt concentration and improving the safety of charcoal resource utilization, thus contributing to the widespread application of hydrothermal carbonization technology.

[0086] Application example:

[0087] (1) Preparation of hydrothermal carbon liquid:

[0088] Hydrothermal carbonization: Cow dung and vegetable waste were used as raw materials, reacted at 220℃ and 260℃ respectively in a hydrothermal carbonization system for 1 hour. In the hydrothermal carbonization (HTC), the ratio of cow dung or vegetable waste to water was 1 kg:10 L, and the pressure inside the reactor was 1.5 MPa. Solid-phase hydrothermal carbon and liquid-phase hydrothermal carbon were obtained. The cow dung-based hydrothermal carbon prepared at 220℃ and 260℃ were designated CM220 and CM260, respectively; the vegetable waste-based hydrothermal carbon prepared at 220℃ and 260℃ were designated GV220 and GV260, respectively.

[0089] Table 1. Basic physicochemical properties of hydrothermal charcoal from manure and vegetable waste sources.

[0090]

[0091] Note: TN: Total Nitrogen; DOC: Dissolved Organic Carbon; AP: Available Phosphorus; AK: Available Potassium.

[0092] (2) Characterization of desalination of hydrothermal carbon liquid:

[0093] The preparation process of the hydrothermal carbonized liquid used for desalination characterization was as follows: pig manure was used as raw material and reacted in a hydrothermal carbonization system at 200℃ for 1 hour; the material ratio of pig manure to water was 1 kg: 10 L. The resulting carbonized liquid was used as the undesalinated carbonized liquid. Desalination was then performed on the obtained carbonized liquid to obtain low-desalinated carbonized liquid and high-desalinated carbonized liquid, respectively. Electrodialysis desalination treatment test parameters: DC voltage 30 V, peristaltic pump 60 RPM, electrodialysis module with 5 cathodes, 5 anodes, and 9 compartments of 5 cm × 10 cm. Desalination for 30 min yielded low-desalinated carbonized liquid, or desalination for 75 min yielded high-desalinated carbonized liquid. 1 L of carbonized liquid was desalinated each time. The low-desalinated carbonized liquid obtained from multiple desalination operations was mixed to obtain the final low-desalinated carbonized liquid, and the high-desalinated carbonized liquid obtained from multiple desalination operations was mixed to obtain the final high-desalinated carbonized liquid. The physicochemical properties of the undesalinated carbonized liquid, low-desalinated carbonized liquid, and high-desalinated carbonized liquid were determined.

[0094] The conductivity of the char liquid is measured by sampling. The degree of desalination (i.e., desalination rate) is determined by the change in the conductivity of the char liquid; specifically, the change in the conductivity of the char liquid corresponds linearly with the degree of desalination.

[0095] Table 2. Basic physicochemical properties of typical carbonized liquids and desalination carbonized liquids

[0096]

[0097]

[0098] (3) Pot experiments were conducted to verify the desalination carbon solution.

[0099] A pot experiment was conducted at the Jiangsu Academy of Agricultural Sciences experimental base in 2024. The tested vegetable varieties were fast-growing butter bok choy and Italian lettuce. Each pot contained 10 kg of soil (soil properties are shown in Table 4), with an effective planting area of ​​0.1 m² / pot. Eight vegetables were planted per pot. The time from sowing to harvest was approximately 35 days for the butter bok choy and approximately 50 days for the Italian lettuce. The control treatment CKU received normal fertilization, equivalent to 225 kg / ha of pure nitrogen, 90 kg / ha of phosphorus (P₂O₅), and 180 kg / ha of potassium (K₂O). Except for CK, all other treatments had the same equivalent pure nitrogen (N) application rate as the CKU group (90 kg / ha of P₂O₅ and 180 kg / ha of K₂O). In this part of the experiment, the applied materials were HAP (non-desalted carbon solution, Table 2), LD-HAP (low-desalted carbon solution, Table 2), and HD-HAP (high-desalted carbon solution, Table 2). The nitrogen replacement rate was 24%-40%, as shown in Table 5. Daily water management used tap water irrigation. The pot experiment showed that the application of desalted carbon solution promoted the macroscopic growth of plants, increased the chlorophyll content of vegetable leaves, significantly promoted the accumulation of plant biomass, and improved plant root parameters, with the high-desalted group showing the best effect. Results are as follows: Figure 7-8 As shown.

[0100] CK was a blank control; CKU was a conventional fertilization control; HAP was a control group treated with non-desalinated charcoal solution; LV and HV were treated with low-desalinated and high-desalinated charcoal solutions, respectively, with the same amount of charcoal solution applied as the HAP treatment; LN and HN were treated with low-desalinated and high-desalinated charcoal solutions, respectively, with the amount of charcoal solution applied as well as the HAP group to achieve the same nitrogen substitution rate. The application methods and timing of the charcoal solution and supplementary urea were identical. After transplanting and stabilizing the seedlings, the total amount was applied in two applications per pot. The first application was 40% of the total amount applied in the early stages when the seedlings were small, and the second application was 60% of the total amount applied in the later stages when the plants had a higher demand for nutrients. The application was evenly distributed around the plants. An iso-nitrogen substitution was used primarily because pig manure charcoal solution has a high total nitrogen content, and vegetables have the highest nitrogen requirement for growth.

[0101] According to the vegetable experiment cycle, taking a fast-growing butter bok choy with a 35-day cycle as an example, transplanting begins 10 days after seedling establishment. The first application of 40% charcoal solution is done 5 days after transplanting (day 15), and the second application of 60% charcoal solution is done 10 days later (day 25). Fertilizer: Superphosphate and potassium chloride are applied as base fertilizer in a single application before transplanting. Urea is applied simultaneously with the charcoal solution (including the single application ratio and application time, i.e., the first application of urea on day 15 (40% of the total urea application), and the second application of urea on day 25 (60% of the total urea application)).

[0102] According to the vegetable experiment cycle, taking Italian lettuce as an example with a 50-day cycle, transplanting begins 12 days after seedling establishment. The first application of 40% charcoal solution is applied 6 days after transplanting (day 18), and the second application (60%) is applied 20 days later (day 38). Fertilizers: Superphosphate and potassium chloride are applied as base fertilizer in a single application before transplanting. Urea is applied simultaneously with the charcoal solution (including the single application ratio and timing, i.e., the first application of urea on day 18 (40% of the total urea application), and the second application of urea on day 38 (60% of the total urea application)).

[0103] The effects of applying undesalinated and desalinated charcoal solutions on the growth (i.e., biomass accumulation) of pak choy and lettuce, such as... Figure 7 As shown. Figure 7 The A in the text corresponds to the bok choy on day 35. Figure 7 B in the text corresponds to the lettuce on day 50.

[0104] As shown in Table 3 and Figure 8 As shown, compared with the control, all treatment groups of desalination charcoal liquid increased the chlorophyll content of plant leaves, significantly promoted the accumulation of plant biomass, and improved plant root parameters. Among them, the high desalination charcoal liquid group showed the best effect. Compared with the control (CK), control (CKU), and control (HAP) groups, the application of desalination carbon solution had a certain impact on the chlorophyll content of pak choi leaves. Compared with the control group, LV, HV, LN, and HN increased by 35.3%, 26.3%, 30.6%, and 25.5%, respectively; compared with the control group, LV, HV, LN, and HN increased by 9.5%, 2.2%, 5.8%, and 1.6%, respectively. The application of desalination carbon solution significantly increased the chlorophyll content of lettuce leaves. Compared with the control group, LV, HV, LN, and HN increased by 45.7%, 62.4%, 50.0%, and 67.5%, respectively; compared with the control group, LV, HV, LN, and HN increased by 37.5%, 53.2%, 41.5%, and 58.1%, respectively.

[0105] Table 3 Plant growth indicators of each treatment group and control group for desalination charcoal liquid

[0106]

[0107]

[0108]

[0109] In Table 3, 1-1, 1-2, 1-3, and 1-4 are four parallel samples.

[0110] The optimal effect on fresh weight of both bok choy and lettuce was observed in the HV group. Compared to CKU and HAP, the fresh weight of bok choy increased by 19.6% and 91.4%, respectively, while the fresh weight of lettuce increased by 18.5% and 175%, respectively. The fresh weight of plants in the HAP group was lower than that of CKU, almost the same as that of CK, indicating that the undesalted charcoal solution inhibits the normal biomass accumulation of lettuce. Dry weight showed a similar effect to fresh weight. The application of desalted charcoal solution had a more significant impact on lettuce roots. Compared to the undesalted group, the average root length of lettuce in the low-desalted group increased by 37.0%, while the average root length of lettuce in the high-desalted group increased by 98.2%. The increase in root growth in the high-desalted group was significantly greater, indicating that a higher degree of desalination can avoid the negative effects of salt stress on lettuce roots.

[0111] Table 4 Basic Properties of Soil

[0112]

[0113] Table 5. Application amounts of carbon solution, urea, superphosphate, and potassium chloride, and N / P replacement rates for each treatment.

[0114]

[0115] Biomass is an important indicator of yield increase. Experiments show that a higher degree of desalination is beneficial. In the experiments, yield increase was achieved with nitrogen replacement rates ranging from 24% to 40%. A higher nitrogen utilization rate can be appropriately adopted to increase the land's capacity to absorb biomass without exceeding the soil's capacity to absorb nutrients and salts.

[0116] (4) Field tests were conducted to verify the desalination carbon solution obtained in (1):

[0117] An in-situ soil column experiment was conducted at the Nanjing Taihe Rice Planting Professional Cooperative. The wheat variety used was Ningmai 33. The total growth period was from November 2023 to May 2024. The wheat soil column experiment employed a planting method of three holes per pot, with three seedlings per hole, using a sowing method. The experimental wheat soil columns were custom-made using PVC material, with a diameter of 50 cm, an effective height of 50 cm, a soil depth of 35 cm, and a surface depth of 15 cm. Urea was used as the nitrogen fertilizer, applied in three stages: basal fertilizer, tillering fertilizer, and heading fertilizer, with a nitrogen fertilizer application ratio of 3:3:4 (mass ratio). Phosphorus fertilizer (P2O5) and potassium fertilizer (K2O) were applied all at once during the basal fertilizer application. The basic physicochemical properties of the soil before tillage are shown in Table 6.

[0118] Table 6. Basic physical and chemical properties of soil before tillage.

[0119]

[0120] In wheat cultivation, the conventional fertilization rate is 240 kg N·m·h. -196kg P ha -1 and 192kg Kha -1 In this part of the study, hydrothermal charcoal liquid was used as a fertilizer synergist, with 200ml applied as basal fertilizer, at the jointing and booting stage, and at the heading stage. The CM220, CM260, GV220, and GV260 groups were treated with 240kgN ha. -1 96kg P ha -1 and 192kg K ha -1 The usual fertilization rate was maintained. The control treatments were no fertilization (CK0) and regular fertilization (CKU). No additional water management was performed routinely. The experimental results showed that, compared with regular fertilization, the additional application of hydrothermal carbon solutions (CM220, CM260, GV220, GV260) acted as fertilizer synergists, significantly promoting wheat root development and growth. Compared with the control group CKU, CM220, CM260, GV220, and GV260 increased protein content by 6.0%, 3.4%, 1.1%, and 2.3%, respectively; CM220, CM260, GV220, and GV260 increased crude fat content by 3.3%, 8.1%, and 3.3%, respectively, while GV260 had no effect on increasing it; CM220, CM260, GV220, and GV260 increased starch content by 5.2%, 6.3%, 3.8%, and 6.6%, respectively; and CM220, CM260, GV220, and GV260 increased yield by 20.8%, 20.4%, 21.7%, and 19.7%, respectively.

[0121] like Figure 9 As shown, compared with CKU, the application of charcoal solution had no significant effect on the growth of wheat at the heading stage, which was reflected in plant height, SPAD value, number of tillers, and number of effective spikes. Slight differences in chlorophyll fluorescence images among the treatments indicated that photosynthesis was slightly stronger after charcoal solution application than after CKU. However, the application of charcoal solution had a significant effect on dry weight and fresh weight, resulting in a marked increase in both.

[0122] like Figure 10 As shown, compared with CKU, the application of charcoal significantly promoted the growth of wheat roots, which was reflected in fresh weight, dry weight, root length, root surface area, root tip and root activity, especially for GV220.

[0123] like Figure 11As shown, compared with CKU, the application of charcoal solution also promoted wheat growth, thereby increasing yield by 19.7%-21.7%. This is also evidenced by indicators such as the number of effective spikes and the thousand-grain weight at wheat maturity. Applying charcoal slightly improved wheat grain quality. Compared with the control group, CM220, CM260, GV220, and GV260 increased protein content by 6.0%, 3.4%, 1.1%, and 2.3%, respectively; CM220, CM260, GV220, and GV260 increased crude fat content by 3.3%, 8.1%, and 3.3%, respectively, while GV260 had no effect; CM220, CM260, GV220, and GV260 increased starch content by 5.2%, 6.3%, 3.8%, and 6.6%, respectively; and CM220, CM260, GV220, and GV260 increased yield by 20.8%, 20.4%, 21.7%, and 19.7%, respectively.

[0124] (5) Hydrothermal carbon synthesis

[0125] Hydrothermal char was prepared using two typical livestock manures (pig manure and cow manure, labeled PM and CM) from a farm in Jiangsu Province. The pressure inside the reactor was 1.5 MPa; the manure-to-water ratio was 1 kg:10 L. During preparation, 5 kg of manure was placed in a high-pressure hydrothermal reactor, using 50 L of water as the solvent and reaction medium, and reacted at 180℃, 220℃, and 260℃ for 1 h, respectively. The obtained manure-derived hydrothermal char was dried in a 90℃ oven, ground to pass through a 2 mm sieve, and stored in sealed reagent bottles. The pig manure-derived hydrothermal char (labeled PCs) prepared at 180℃, 220℃, and 260℃ were designated PC180, PC220, and PC260, respectively. The cow manure-derived hydrothermal char (CCs) prepared at 180℃, 220℃, and 260℃ were designated CC180, CC220, and CC260, respectively. The basic physicochemical properties of different feces and their source hydrothermal carbon are shown in Table 7.

[0126] Table 7. Basic physicochemical properties of different feces and their source hydrothermal carbon.

[0127]

[0128]

[0129] Note: The material ratio for hydrothermal carbonization (HTC) is 1:10, and the residence time is 1 hour. PC180, PC220, and PC260 are hydrothermal carbons of pig manure prepared at 180℃, 220℃, and 260℃, respectively; CC180, CC220, and CC260 are hydrothermal carbons of cow manure prepared at 180℃, 220℃, and 260℃, respectively. The solid-liquid ratio for pH measurement is 1:10. Zeta potential is measured at pH=7 using water as the dispersant. C, N, H, and S are determined using an elemental analyzer, and O(%) = 100% - C% - N% - H% - S% - Ash%. SSA is the specific surface area, PV is the pore volume, APD is the average pore size, and nitrogen is the carrier gas. ND indicates no detection.

[0130] (5) The hydrothermal carbon obtained in (4) was subjected to a soil column test to verify its performance.

[0131] A rice soil column experiment was conducted at the Jiangsu Academy of Agricultural Sciences experimental base. The tested rice variety was Nanjing 46. Rice seedlings for the soil column experiment were transplanted on June 23, 2021, using a planting method of three plants per hole per pot. The nitrogen fertilizer used in the experiment was urea, applied three times: basal fertilizer, tillering fertilizer, and panicle fertilizer, on June 25, July 6, and August 19, 2021, respectively, with a nitrogen fertilizer application ratio of 3:3:4. Phosphate fertilizer (P2O5) and potassium fertilizer (K2O) were applied once during the basal fertilizer application. The basic properties of the tested soil were as follows: pH = 5.27, organic carbon 17.02 g·kg⁻¹. -1 Total nitrogen 1.88 g·kg -1 Total phosphorus 0.455 g·kg -1 Total potassium 12.4 g·kg -1 8.2 mg / kg of readily available phosphorus -1 Available potassium 82.6 mg·kg -1 Alkaline nitrogen uptake: 165.8 mg / kg -1 In this study, the nitrogen and phosphorus fertilizers were reduced by 20% and 30% (mass fraction), respectively, in the treatment with the application of manure and manure-derived hydrothermal char (MHCs), while the control treatment received normal fertilization. Routine water management involved irrigation with tap water, maintaining a water level of 3-5 cm on the paddy field surface. The experimental paddy soil columns were custom-made from PVC material, with a diameter of 30 cm and an effective height of 50 cm. Each column contained 35 kg of paddy soil, with the topsoil comprising the first 20 cm of the column. Manure and its MHCs were mixed with the topsoil at a ratio of 0.5% (i.e., the mass ratio of MHCs to topsoil was 0.5%) before being incorporated into the column. No other materials were applied to the remaining subsoil.

[0132] Soil column experiments showed that manure hydrothermal biochar possesses unique properties and abundant nutrients. When applied to paddy fields with reduced nitrogen and phosphorus fertilizer application, it can meet the nutrient requirements for rice growth and development while reducing the risk of soil nitrogen and phosphorus loss and the loss of reactive gaseous nitrogen. For example, the reduction effect of MHCs on important reactive gaseous nitrogen (N2O and NH3) in paddy soil is largely influenced by the raw materials used. Pig manure hydrothermal biochar (PCs) showed a better N2O reduction trend, with a reduction range of 25.0-28.4%; while cow manure hydrothermal biochar (CCs) did not significantly change soil N2O emissions; direct application of manure to the field did not show any reduction effect. Besides the influence of PCs themselves on soil aeration, reducing the concentration of substrates for denitrification (10.1-66.9% nitrate nitrogen) and lowering the activities of nitrate reductase and nitrite reductase inhibits the denitrification process and reduces N2O formation. Soil NH3 volatilization decreased significantly after the application of manure and its MHCs, with reductions ranging from 38.7% to 54.5%. Figure 3-6 As shown in Tables 9 and 10, the effects of different manure and hydrothermal char application on rice growth and yield are illustrated.

[0133] The experimental treatments, numbering, and fertilization amounts are shown in Table 8.

[0134] Table 8. Experimental Treatments, Numbers, and Fertilizer Application Amounts

[0135]

[0136] Table 9. Effects of different types of manure and hydrothermal char on rice growth.

[0137]

[0138] Note: Lowercase letters indicate significant differences between the control and fecal and MHCs treatments. If no matching letter is found, the difference between the treatments is significant (P<0.05).

[0139] Table 10 Effects of different manure types and hydrothermal char application on rice yield

[0140]

[0141] The trends in the concentration changes of ammonium nitrogen and nitrate nitrogen in field surface water were roughly the same for different manure and MHCs treatments. For example... Figure 3As shown in (a), except for the PK treatment where the ammonium nitrogen concentration in the field water remained consistently low, the peak ammonium nitrogen concentration in the field water for the other treatments occurred on days 1-2 of the fertilization period. The application of inorganic nitrogen fertilizer at the initial stage of basal fertilization caused the ammonium nitrogen concentration in the field water to peak on days 1-3 of the fertilization period. Except for the PM and CC180 treatments, the peak ammonium nitrogen concentration in the NPK treatment was higher than that of the other treatments, and gradually decreased as the fertilization period progressed. During the tillering stage, after the addition of inorganic nitrogen fertilizer, the ammonium nitrogen concentration in the field water reached its peak on day 1 of the fertilization period, and then gradually decreased. Among these, except for the PM and PC180 treatments, the ammonium nitrogen concentration in the NK treatment remained higher than that of the other treatments during the tillering stage. During the heading stage, the ammonium nitrogen concentration in the field water reached its peak on days 1-3 of the fertilization period, and was generally lower than that of the previous two fertilization periods. Figure 3 As shown in (b), the peak concentration of nitrate nitrogen in field water generally occurred on day 7 of the three fertilization stages. The overall nitrate nitrogen concentration in field water was relatively low during the basal fertilization stage, with the NPK treatment showing the largest peak. During the tillering stage, the overall nitrate nitrogen concentration in field water was higher in the CM and NPK treatments than in other treatments, with the peak values ​​for CM and NPK treatments occurring on days 5 and 7, respectively. The nitrate nitrogen concentration in field water further increased during the heading stage, with the CC180 treatment showing an overall higher concentration than other treatments, and the peak value occurring on day 7 of the fertilization stage.

[0142] like Figure 4 As shown, the trends in phosphorus concentration in field surface water were roughly the same for different manure and MHC treatments, with the PM treatment exhibiting a higher concentration. The peak concentrations of phosphorus in field surface water for all three fertilization stages occurred on the first day of each fertilization period, and gradually decreased as the fertilization period progressed. Specifically, the peak concentrations of phosphorus in field surface water were highest in the PK and NPK treatments at the initial stage of basal fertilization, followed by a rapid decline. In the later stage of basal fertilization, the PM treatment maintained a consistently high concentration of phosphorus in field surface water. During the tillering stage, the phosphorus concentrations in all treatments were significantly lower than those during the basal fertilization stage. Furthermore, the PM treatment had a higher concentration of phosphorus in field surface water than the other treatments. After two months of rice growth, most of the phosphorus in the field surface water was absorbed and utilized by the plants, resulting in consistently low phosphorus concentrations during the heading stage, with no significant differences between treatments.

[0143] like Figure 5 As shown, the soil N2O emission flux in paddy fields after the application of different manure and its MHCs was as follows: Figure 5 As shown, the overall trends in N2O emission fluxes across different treatments were similar. During the basal and tillering stages, the soil was consistently flooded, resulting in low soil N2O emission fluxes. However, as the fertilization period progressed, the soil water layer gradually decreased during the drying stage, leading to a gradual increase in soil N2O emission fluxes, peaking on day 40 after rice transplanting, followed by a gradual decline. N2O emission fluxes remained low during the panicle stage and generally remained low thereafter.

[0144] Calculations of cumulative soil N2O emissions during rice growth indicate that MHCs may show a better N2O reduction trend than manure treatment, but the effect varies significantly depending on the raw materials used. The effects of applying different manures and their MHCs on cumulative soil N2O emissions are inconsistent. Compared to NPK, PM application showed an increasing trend in cumulative soil N2O emissions, from 30.24 mg·m³. -2 It rose to 32.42 mg·m -2 The increase was 7.2%, but the increasing trend was not significant (P>0.05); while the application of PCs showed an effect of inhibiting soil N2O emissions, with the cumulative soil N2O emissions of PC180 and PC260 decreasing to 22.67 mg·m³. -2 and 21.64 mg·m -2 The N2O emissions were significantly reduced by 25.0% and 28.4% (P<0.05). However, the application of CM and CCs promoted soil N2O emissions, with CM, CC180, and CC260 increasing to 33.64 mg·m³. -2 34.30 mg·m -2 and 35.99 mg·m -2 The treatment increased cumulative soil N2O emissions by 11.3%, 13.4%, and 19.0%, respectively, but the changes were not significant (P>0.05). Fecal treatment had no significant effect on soil N2O emissions. Different MHCs had inconsistent effects on soil N2O emissions. CCs had no significant effect on increasing N2O emissions, while PCs treatment showed better N2O reduction.

[0145] like Figure 6 As shown in the figure, NH3 volatilization in paddy field soil is another pathway for the loss of active gaseous nitrogen in the soil. The effects of different manure types and their MHCs on this pathway are illustrated in the figure. Figure 6 It can be seen that soil NH3 volatilization is mainly concentrated during the basal fertilizer and tillering fertilizer stages, while the overall soil NH3 volatilization flux is lower during the heading fertilizer stage compared to the previous two fertilizer stages. Compared with NPK, the soil NH3 volatilization of manure and its MHCs showed a significant decreasing trend. The peak soil NH3 volatilization flux during the basal fertilizer stage occurred on days 2-4, with the soil NH3 volatilization flux of NPK being significantly higher than other treatments overall, peaking on day 2 at 16.43 kg·hm². -2 ·d -1 The peak NH3 volatilization flux in the soil during the tillering period occurred on days 1-3. Similarly, the overall NH3 volatilization flux in the NPK treatment was significantly higher than that in other treatments, with the peak NH3 volatilization flux occurring on day 1 at 14.62 kg·hm². -2 ·d -1 The overall NH3 volatilization flux in the soil was relatively low during the heading and fertilization stages, with the emission peak occurring on the 2nd-3rd day. Among them, PC180 had the highest peak NH3 volatilization flux in the soil, at 5.44 kg·hm².-2 ·d -1 From the perspective of soil NH3 volatilization flux, the treatment of manure and its MHCs has shown a significant emission reduction trend during the basal fertilizer and tillering fertilizer periods.

[0146] Calculations of soil NH3 volatilization accumulation under each treatment during the three fertilization periods showed that the soil NH3 volatilization accumulation significantly decreased after application of different manures and their MHCs (P<0.05). Compared with NPK, PM, PC180, and PC260 decreased from 152.31 kg·hm². -2 ·d -1 They decreased to 71.39 kg·hm -2 83.82 kg·hm -2 and 78.53 kg·hm -2 The concentrations of PM2.5, CC180, and CC260 decreased by 53.1%, 45.3%, and 48.4%, respectively. The soil NH3 volatilization accumulation of PM2.5 was lower than that of PC2, but the difference was not statistically significant (P>0.05). Meanwhile, CM2, CC180, and CC260 decreased to 85.15 kg·hm2. -2 93.37 kg·hm -2 and 69.28 kg·hm -2 The treatments reduced soil NH3 volatilization accumulation by 44.1%, 38.7%, and 54.5%, respectively. CM treatment showed better NH3 reduction than CC180 but worse than CC260. There was no significant difference between the CM and CCs treatments (P>0.05). Based on the cumulative volatilization, the basal fertilizer period and the tillering fertilizer period were the main periods for soil NH3 reduction using manure and its MHCs.

[0147] The above embodiments are only used to illustrate the technical solutions of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. An application of a mobile photovoltaic-powered subcritical fertilizer production system for nitrogen and phosphorus emission reduction and efficiency improvement, and resource utilization of high-moisture waste, characterized in that: Includes the following steps: In the solar water tank (8), the water required for the hydrothermal carbonization reaction is preheated. This process is monitored and controlled by the PLC controller (7). After the temperature is raised, the water is transported to the reactor (13) through the water pump (10) and the shut-off valve (11). The hydrothermal carbonization reaction feedstock is added through the inlet of the feeder (12) and then transported to the feed inlet (17) of the reactor (13) through the outlet of the feeder (12). The hydrothermal carbonization reaction feedstock is manure, the reaction temperature is 180-260 ℃, the reaction time is 1-2 h, and the mass-to-volume ratio of manure to water in the hydrothermal carbonization reaction is 1 kg: 9-11 L. The manure is cow manure or pig manure. The agitator (19) in the reactor (13) rotates at 200-300 r / min and is used for stirring the feedstock during the hydrothermal carbonization process. The reactor (13) is completely sealed during the hydrothermal carbonization process, and the internal pressure of the reactor (13) is 1.0-1.

8. After the reaction is completed, the reactor (13) is cooled. After the reactor (13) is depressurized, the reactor can be opened to discharge the product. The product is fed from the discharge port (20) of the reactor (13) into the filter press (14) by means of the water pump (10) and the shut-off valve (11). The solid-liquid separation of the product is carried out by the filter press method, so that the water content of the hydrothermal carbon is less than 30%. The hydrothermal carbon is stored in the solid storage device (15), and the carbon liquid is stored in the liquid storage device (16). The carbon liquid enters the electrodialysis device (21) from the liquid storage device (16) and is subjected to electrodialysis under the conditions of DC voltage 25-35V and 40-80 RPM. The desalination rate is 80%-90% and the electrodialysis time is 15-120min, resulting in a desalinated carbon liquid with a conductivity of 1.40±0.15mS / cm. Desalinated carbon solution is applied as fertilizer to the soil for plant growth, with a nitrogen replacement rate of 24%-40%. For fast-growing bok choy and Italian lettuce, desalinated carbon solution is applied twice: the first time during the seedling stage and the second time during the middle and late stages of plant growth, with a mass ratio of 2:2.5-3.5 between the first and second applications. For wheat, desalinated carbon solution is applied three times, with the application amounts being roughly equal at the basal fertilizer, tillering fertilizer, and heading fertilizer stages. When desalinated carbon liquid is applied as fertilizer to the soil for plant growth, it increases the chlorophyll content of plant leaves, promotes the accumulation of plant biomass, and increases the root length of plants.

2. The application of the mobile photovoltaic-powered subcritical fertilizer production system according to claim 1, which is aimed at reducing nitrogen and phosphorus emissions and improving efficiency, as well as the resource utilization of high-moisture waste, is characterized in that... A mobile photovoltaic-powered subcritical fertilizer production system for nitrogen and phosphorus emission reduction and efficiency improvement, as well as resource utilization of high-moisture waste, includes a solar preheating system, a photovoltaic power supply system, an auxiliary heating system, a hydrothermal reaction system, and a post-treatment system. The photovoltaic power supply system and the auxiliary heating system are connected to the electrical load of the hydrothermal reaction system; the hydrothermal reaction system is connected to both the solar preheating system and the post-treatment system. The solar preheating system includes a heat pipe solar collector (9), a solar water tank (8), a PLC controller (7), a water pump (10), and a shut-off valve (11); one side of the solar water tank (8) is connected to the hydrothermal reaction system through the water pump (10) and the shut-off valve (11), and the other side is connected to the PLC controller (7) through a pipeline; the solar water tank (8) and the heat pipe solar collector (9) are connected in parallel and fixed by a bracket; The photovoltaic power supply system includes a photovoltaic module (1), a photovoltaic controller (2), a battery pack (3), an inverter (4), and a distribution box (5); the output terminal of the photovoltaic module (1) is connected to the input terminal of the photovoltaic controller (2); the output terminal of the photovoltaic controller (2) is connected to the input terminal of the battery pack (3); the output terminal of the battery pack (3) is connected to the input terminal of the inverter (4); the output terminal of the inverter (4) is connected to the input terminal of the distribution box (5); and the output terminal of the distribution box (5) is connected to the electrical load of the hydrothermal reaction system. The auxiliary heating system includes an auxiliary heater (6); the output end of the auxiliary heater (6) is connected to the electrical load of the hydrothermal reaction system; The hydrothermal reaction system includes a feeder (12), a reactor (13), a filter press (14), a solid storage device (15), and a liquid storage device (16); the feeder (12) is connected to the feed inlet (17) of the reactor (13); the discharge outlet (20) of the reactor (13) is connected to the filter press (14); the filter press (14) is connected to both the solid storage device (15) and the liquid storage device (16); the liquid storage device (16) is connected to the electrodialysis device (21); The post-processing system includes an electrodialysis unit (21); the inlet of the electrodialysis unit (21) is connected to the outlet of the liquid storage device (16).

3. The application of the mobile photovoltaic-powered subcritical fertilizer production system according to claim 2, which is aimed at reducing nitrogen and phosphorus emissions and improving efficiency, as well as the resource utilization of high-moisture waste, is characterized in that... The solar water tank (8) in the solar preheating system is connected to the heat pipe solar collector (9). The inner wall of the heat pipe solar collector (9) is equipped with a temperature sensor and is connected to the PLC controller (7). The bottom of the heat pipe solar collector (9) is fixed by a bracket; The solar water tank (8) has an inlet at one end and an outlet at the other end, and is equipped with a shut-off valve.

4. The application of the mobile photovoltaic-powered subcritical fertilizer production system according to claim 2, which is aimed at reducing nitrogen and phosphorus emissions and improving efficiency, as well as the resource utilization of high-moisture waste, is characterized in that... The photovoltaic power supply system has at least one set of photovoltaic modules (1) and is provided with a base; the battery pack (3) in the photovoltaic power supply system contains at least two batteries, which are connected in series.

5. The application of the mobile photovoltaic-powered subcritical fertilizer production system according to claim 2, which is aimed at reducing nitrogen and phosphorus emissions and improving efficiency, as well as the resource utilization of high-moisture waste, is characterized in that... The feeder (12) has a sample inlet on the top and a sample outlet on the side. The sample outlet of the feeder (12) is connected to the feed inlet (17) of the reactor (13). The reactor (13) includes a motor (18) and a stirrer (19). The inlet of the filter press (14) is connected to the outlet (20) of the reactor (13), and is equipped with a water pump (10) and a shut-off valve (11). The outlet of the filter press (14) is connected to the solid storage device (15) and the liquid storage device (16); The product storage devices used in the hydrothermal reaction stage include solid storage devices (15) and liquid storage devices (16).

6. The application of the mobile photovoltaic-powered subcritical fertilizer production system according to claim 2, which is aimed at reducing nitrogen and phosphorus emissions and improving efficiency, as well as the resource utilization of high-moisture waste, is characterized in that... The outlet of the liquid storage device (16) is connected to the inlet of the electrodialysis device (21) via a pipeline.

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