A compost carbon sequestration and emission reduction method based on homologous biochar segmented addition

Abstract

The present application relates to the technical field of agricultural solid waste treatment, and discloses a composting carbon sequestration and emission reduction method based on homologous biochar segmented addition, which comprises the following steps: S100, material mixing and initial biochar addition, mixing tobacco straw aggregate with treated sheep manure, and adding 30-35% of homologous tobacco straw biochar based on the total added weight; S200, aerobic fermentation start; S300, high-temperature period biochar injection, monitoring the core temperature of the mixed material, when the specific high-temperature duration and the triggering condition of the temperature drop inflection point are met, the remaining homologous tobacco straw biochar is pre-wetted and deeply injected into the high-temperature zone; S400, fermentation and maturation and discharging. The present application supplements the un-plugged pores in the high-temperature fermentation period through the segmented addition process, inhibits the metabolism of methanogenic bacteria, promotes the conversion of free carbon into stable humic carbon, and realizes the long-term sequestration of organic carbon in agricultural solid waste.

Description

Technical Field

[0001] This invention relates to the field of agricultural solid waste treatment technology, specifically to a composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar. Background Technology

[0002] Aerobic fermentation composting of agricultural solid waste is a fundamental process for realizing the resource utilization and harmless treatment of organic waste. During the aerobic fermentation of agricultural solid waste, organic matter undergoes degradation and transformation under the metabolic action of microorganisms, generating humus and releasing heat. To control carbon loss during fermentation and enhance the agricultural value of compost products, introducing biochar into the composting system has become a key research focus in carbon sequestration and emission reduction technologies. Biochar, with its porous structure and surface functional groups, can adsorb soluble organic carbon during composting and interfere with the biochemical transformation pathways of carbon and nitrogen, making it a conventional carbon-based material for achieving synergistic carbon sequestration and emission reduction through composting.

[0003] Current technologies for biochar-assisted composting typically employ a one-time pre-mixing process. During the material preparation stage before fermentation and composting, operators mix a predetermined ratio of dried biochar with basic composting materials such as straw and livestock manure in a mixing device. After thorough mixing, the biochar-containing mixture is transported to the fermentation tank to build the compost pile, and then the ventilation equipment is activated to begin the aerobic fermentation process. Throughout the fermentation heating, high-temperature, and maturation stages, the mixture undergoes biochemical succession based on the material structure established in the early stages of fermentation. The physical pores of the biochar participate in the adsorption and biochemical reactions within the mixture from the very beginning of fermentation.

[0004] In the initial heating stage of composting fermentation, existing technologies produce water-soluble small-molecule organic matter and microbial metabolic colloids from the decomposition of easily degradable organic matter. These substances rapidly fill and block the physical pores of the biochar. When the mixture enters the high-temperature fermentation stage, characterized by intense carbon mineralization, solid organic matter decomposes into free soluble organic carbon. However, the biochar added during this high-temperature fermentation stage has already lost its adsorption and retention capacity. The lack of adsorption sites prevents the physical retention of soluble organic carbon, which is then converted into carbon dioxide and methane by microbial metabolism and released into the environment. This results in an increase in greenhouse gas emissions from the fermentation system and a decrease in total carbon retention. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar, which solves the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar, implemented using a trough-type aerobic fermentation reaction system, consists of the following steps: S100, Material Mixing and Initial Biochar Addition: Tobacco straw and sheep manure are mixed to prepare a basic compost mixture with a carbon-to-nitrogen ratio of 25:1 to 30:1 and a moisture content of 55% to 65%; In the preparation of the basic compost mixture, 30% to 35% of the total weight of the same source of tobacco straw biochar is added; Based on dry matter weight, the basic compost mixture is 100 parts, and the same source of tobacco straw biochar is 5 to 20 parts; S200, Aerobic Fermentation Start-up: Place the mixture of added tobacco straw biochar in a trough reactor to start fermentation; turn on the ventilation and aeration equipment of the trough reactor to continuously supply oxygen to the mixture, so that the mixture enters an aerobic heating state. S300, High-Temperature Biochar Injection: Triggering conditions are set by monitoring the temperature change curve of the mixed material core; when the core temperature of the mixed material reaches 60℃ or above and is maintained for 48 to 72 hours, and the temperature drops by 1℃ or more for 6 consecutive hours, the supplementary injection operation is triggered; after the triggering conditions are met, the remaining 65% to 70% of the homologous tobacco straw biochar is pre-wetted, and the pre-wetted homologous tobacco straw biochar is injected into the high-temperature zone of the mixed material through a deep rotary tillage device; S400, Fermentation and Discharge: After the injection operation is completed, the mixture enters the cooling and decomposition period; the mixture is turned in sections according to the set turning cycle and the moisture content of the mixture is controlled until the compost product is decomposed.

[0007] The innovative principles and technical mechanisms of this invention are as follows: This invention is based on the principle of matching the physicochemical properties of homologous biochar with the microecological environment of the basic compost mixture. Homologous tobacco straw biochar is prepared by pyrolysis carbonization at 400℃ to 600℃ using tobacco straw from the same source as the tobacco straw aggregate. Using homologous materials in the mixture can avoid the toxic inhibition of microorganisms by heterologous biochar, maintain the metabolic activity of carbon-degrading enzymes such as cellulase, ligninase, and dehydrogenase, and accelerate the biochemical decomposition of recalcitrant straw carbon components.

[0008] This invention changes the traditional one-time biochar addition process, employing a staged addition method to regulate the carbon conversion pathway of the mixed materials. During the material mixing stage, 30% to 35% of homologous tobacco straw biochar is added. The alkaline ash produced by pyrolysis neutralizes the organic acids generated in the early stages of fermentation, maintaining the pH of the mixed material pile between 6.5 and 8.0, providing an initial colonization environment for carbon-degrading microorganisms. The core purpose of limiting the initial addition amount is to prevent water-soluble small-molecule organic matter and microbial metabolic colloids generated in the early stages of fermentation from filling all physical pores.

[0009] During the high-temperature fermentation period, after the core temperature is maintained at 60℃ or above for 48 to 72 hours, the solid organic matter inside the mixture decomposes to produce free soluble organic carbon and soluble organic nitrogen. At this point, the initially added homologous tobacco straw biochar reaches adsorption saturation. When the temperature drops by more than 1℃ for 6 consecutive hours, it marks the end of the peak stage of carbon mineralization heat production. During the fermentation stage that meets the temperature drop characteristics, the remaining 65% to 70% of the homologous tobacco straw biochar is injected through pre-wetting treatment combined with deep rotary tillage. The combination of pre-wetting treatment and deep rotary tillage introduces unblocked physical pores into the mixture while avoiding thermal shock to the high-temperature microecological community and preventing a sudden increase in local oxygen supply. The supplemented homologous tobacco straw biochar adsorbs and retains free soluble organic carbon, reducing the carbon dioxide emission flux; at the same time, the porous structure of the homologous tobacco straw biochar breaks down the anaerobic microzones inside the mixture, inhibits the metabolic activity of methanogenic bacteria, and cuts off the methane generation pathway.

[0010] During the fermentation cooling and maturation stages, the retained soluble organic carbon remains in the mixed materials as precursors. Under mesophilic aerobic conditions, lignin-degrading bacteria utilize these precursors for metabolic activities. Catalyzed by oxygen-containing functional groups on the surface of the homologous tobacco straw biochar, the humic precursors undergo condensation and polymerization reactions, promoting the transformation of straight-chain aliphatic carbon into structurally complex aromatic carbon, forming stable humic carbon.

[0011] This invention provides a composting method for carbon sequestration and emission reduction based on the staged addition of homologous biochar. It has the following beneficial effects: 1. This invention solves the problem of premature pore blockage caused by single-stage addition of homologous tobacco straw biochar by adding it in stages. Based on the characteristics of the core temperature drop, the peak inflection point of carbon mineralization is determined, and pre-wetted homologous tobacco straw biochar is deeply injected into the mixture during the high-temperature period. The introduced unblocked pores trap free soluble organic carbon and soluble organic nitrogen, while the rotary tillage action simultaneously eliminates anaerobic microzones and inhibits methanogenic bacteria metabolism. The staged addition process improves the total carbon retention rate of the mixture, reduces carbon dioxide and methane emission fluxes, and achieves carbon sequestration and emission reduction in the composting system.

[0012] 2. This invention utilizes homologous tobacco straw biochar to retain soluble organic carbon released during high-temperature periods, reshaping the organic carbon skeleton of the mixed materials. The retained small-molecule carbon sources act as precursors in the later stages of fermentation, undergoing condensation and polymerization reactions catalyzed by oxygen-containing functional groups on their surfaces. The condensation process promotes the conversion of linear aliphatic carbon into aromatic carbon, increasing the degree of polymerization of aromatic rings in humic molecules. The condensation reaction and physical adsorption transform easily mineralized and degraded free carbon into stable humic carbon with anti-degradation capabilities, enhancing the molecular structural stability of compost products and achieving long-term sequestration of organic carbon.

[0013] 3. This invention introduces homologous tobacco straw biochar to construct a fermentation microecological environment that matches the mixed materials, overcoming the toxic inhibitory effect of heterologous substances on microbial metabolism. In the early stages of fermentation, the homologous tobacco straw biochar neutralizes accumulated organic acids, maintaining the system's pH balance, and utilizes its pores to provide colonization space for native carbon-degrading microorganisms. This colonization environment promotes the enrichment of functional enzymes such as cellulase and ligninase, accelerating the biochemical decomposition of recalcitrant straw carbon. The enhanced microecological activity provides precursors for subsequent humus synthesis, forming a synergistic reaction system of physical adsorption and biodegradation. Attached Figure Description

[0014] Figure 1 This is a flowchart of a composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see the appendix Figure 1 This invention provides a method for carbon sequestration and emission reduction through staged addition of homologous biochar in composting. The basic material includes a carbon sequestration and emission reduction tobacco straw-sheep manure compost composition. This composition comprises a basic compost mixture and homologous tobacco straw biochar. By dry matter weight, the basic compost mixture comprises 100 parts, and the homologous tobacco straw biochar comprises 5 to 20 parts. The basic compost mixture consists of tobacco straw as aggregate and sheep manure. Homologous tobacco straw biochar refers to a carbon-based material prepared by pyrolysis of tobacco straw from the same source as that in the basic compost mixture. Using homologous materials in the mixture ensures that the physicochemical properties of the homologous tobacco straw biochar match the microecological environment of the basic compost mixture, maintaining the activity of carbon-degrading enzymes such as cellulase, ligninase, and dehydrogenase in the basic compost mixture.

[0017] The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar relies on a trough-type aerobic fermentation reaction system. For the construction of the basic infrastructure of the trough-type aerobic fermentation reaction system, those skilled in the art can refer to the standards of conventional large-scale composting plants. The basic construction of the trough-type aerobic fermentation reaction system is well-known technology in this field and will not be elaborated further here.

[0018] The overall process flow of the composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar is divided into the following steps: S100: Material Mixing and Initial Biochar Addition. In step S100, tobacco straw and sheep manure are mixed to prepare a basic compost mixture with a carbon-to-nitrogen ratio of 25:1-30:1 and a moisture content of 55%-65%. During the preparation of the basic compost mixture, 30%-35% of the total weight of homologous tobacco straw biochar is added. This addition in step S100 neutralizes the organic acids produced in the early stages of fermentation of the basic compost mixture and provides an initial colonization environment for carbon-degrading microorganisms.

[0019] S200: Aerobic fermentation start-up. The mixture containing the same source of tobacco straw biochar is placed in a trough reactor to start fermentation. In step S200, the ventilation and aeration equipment of the trough reactor is turned on to continuously oxygenate the mixture, allowing it to enter an aerobic and heating state.

[0020] S300: High-Temperature Biochar Injection. Conventional one-time addition methods can prematurely clog the physical pores of the biochar in steps S100 and S200. Step S300 sets trigger conditions by monitoring the temperature change curve of the mixed material core. When the core temperature of the mixed material reaches 60℃ or above, is maintained for 48-72 hours, and the temperature decreases by 1℃ or more within 6 consecutive hours, a follow-up injection is triggered. After the trigger conditions are met, the remaining 65%-70% of the homologous tobacco straw biochar is pre-wetted and injected into the high-temperature zone of the mixed material using a deep rotary tillage device. The combination of pre-wetting and deep rotary tillage injection, while avoiding sudden increases in local oxygen supply and thermal shock, utilizes the unblocked physical pores of the homologous tobacco straw biochar to adsorb and retain soluble organic carbon and soluble organic nitrogen, and reduces the metabolic activity of methanogenic bacteria, thereby reducing carbon dioxide and methane emissions. The retained soluble organic carbon and soluble organic nitrogen remain in the mixture as precursors for synthesis.

[0021] S400: Fermentation and Composting. After the injection operation in step S300, the mixture enters the cooling and composting period. In step S400, the mixture is turned over in stages according to the set turning cycle, and the moisture content of the mixture is controlled until the compost product is fully decomposed. During the composting process in step S400, the recalcitrant straw carbon inside the compost product is converted into stable humic carbon with aromatic structural characteristics, completing the total carbon sequestration of the entire composting cycle.

[0022] To perform step S100 as described above, it is necessary to pretreat the basic raw materials of the carbon sequestration and emission reduction tobacco straw-sheep manure compost composition and prepare homologous tobacco straw biochar. The pretreatment of the basic raw materials and the preparation of homologous tobacco straw biochar are subordinate steps to step S100 and are divided into steps S101 to S105.

[0023] S101: Preparation of Tobacco Straw Aggregate. Collect tobacco straw and remove inorganic impurities. Feed the tobacco straw, after removing inorganic impurities, into a mechanical pulverizer for mechanical pulverization. Sieve the pulverized tobacco straw through a vibrating screen to separate and intercept the pulverized straw with a particle size in the range of 10-30 mm as tobacco straw aggregate. The 10-30 mm particle size range provides a supporting framework for the base mixture, ensuring that the base mixture has free porosity to meet the ventilation and oxygen supply requirements of aerobic microorganisms during the aerobic fermentation stage. For the process of removing inorganic impurities from tobacco straw and the mechanical structure of the mechanical pulverizer, those skilled in the art can refer to conventional agricultural solid waste treatment manuals. The inorganic impurity removal process and pulverizer structure are well-known technologies in this field and will not be elaborated further here.

[0024] S102: Pyrolysis of Homologous Tobacco Straw Biochar. Tobacco straw from the same source as in step S101 is used. The uncrushed or crushed tobacco straw is placed in an anaerobic pyrolysis furnace for pyrolysis and carbonization. The pyrolysis parameters of the anaerobic pyrolysis furnace are set as follows: the furnace is heated to a target pyrolysis temperature of 400-600℃ at a heating rate of 5-15℃ / min, and maintained at this temperature for 2-4 hours. At the set heating rate and target pyrolysis temperature, the cellulose and hemicellulose inside the tobacco straw undergo thermal decomposition, generating a carbon-based framework with microporous and mesoporous structures. The target pyrolysis temperature range of 400-600℃ preserves the oxygen-containing functional groups on the surface of the homologous tobacco straw biochar, enabling it to possess cation exchange capacity and the ability to chemically bond with soluble organic carbon.

[0025] S103: Grading of Homologous Tobacco Straw Biochar. The homologous tobacco straw biochar produced by the pyrolysis in step S102 is cooled to room temperature under anaerobic conditions. The cooled homologous tobacco straw biochar is then crushed using a crusher. The crushed homologous tobacco straw biochar is graded through a mesh screen, and carbon particles with a diameter in the range of 1-5 mm are collected as homologous tobacco straw biochar. The 1-5 mm particle size range ensures that the homologous tobacco straw biochar has a specific surface area for adsorbing soluble organic nitrogen and soluble organic carbon, and prevents the pores of the base mixture from being blocked by fine carbon powder due to excessively small particle size.

[0026] S104: Adjusting the Moisture Content of Sheep Manure. Test the initial moisture content of fresh sheep manure. If the initial moisture content of fresh sheep manure exceeds 75%, add a drying aid to dehydrate the fresh sheep manure, or reduce the moisture content to between 60% and 70% by natural air drying. Setting the moisture content of sheep manure below 70% can prevent the sheep manure from forming clumps when mixed with tobacco straw aggregate, thus preventing the formation of localized anaerobic environments in the early stages of fermentation.

[0027] S105: Mixture Preparation and Initial Biochar Addition. The tobacco straw aggregate prepared in step S101, the sheep manure treated in step S104, and a portion of the homologous tobacco straw biochar prepared in step S103 are fed into a twin-shaft mixer for mixing. During the mixing operation, the weight ratio of tobacco straw aggregate to sheep manure is calculated based on the initial carbon-nitrogen ratio and moisture content of the tobacco straw aggregate and the sheep manure, maintaining the overall carbon-nitrogen ratio of the base mixture between 25:1 and 30:1. In the simultaneous operation of adjusting the overall carbon-nitrogen ratio, 30%-35% of the total weight of homologous tobacco straw biochar is added to the twin-shaft mixer. The overall moisture content of the mixture in the twin-shaft mixer is adjusted to 55%-65% by spraying water or adding dried tobacco straw aggregate. Within a carbon-to-nitrogen ratio range of 25:1 to 30:1, the carbon and nitrogen source ratios meet the nutritional requirements of carbon-degrading microorganisms. A total water content of 55%-65% can dissolve soluble organic matter and maintain the thickness of the liquid film on the surface of the base mixture, providing a liquid-phase mass transfer channel for the biochemical metabolism of microorganisms.

[0028] After completing the mixture preparation and initial biochar addition in step S105, the process enters the pile building and early fermentation microecological construction stage. This stage is divided into steps S106 to S109.

[0029] S106: Composting the Mixture. The mixture output from step S105 is transported to the fermentation tank of the trough-type aerobic fermentation reaction system, and the mixture is stacked to form a compost pile. The stack height of the compost pile is controlled to be 1.2-1.5m. A stack height of 1.2-1.5m can balance the heat accumulation inside the compost pile with the physical pressure borne by the bottom layer of the compost. A stack height below 1.2m will cause the compost pile to dissipate heat too quickly, preventing the compost pile from reaching the temperature threshold required for subsequent fermentation processes. A stack height above 1.5m will cause excessive pressure on the bottom layer of the compost, resulting in a decrease in free porosity and triggering anaerobic fermentation at the bottom. For the feeding equipment that transports the mixture to the fermentation tank, those skilled in the art can use a conventional track feeder from a trough-type composting production line. The mechanical structure of the feeding equipment is well-known in the art and will not be described in detail here.

[0030] S107: Organic Acid Neutralization Reaction. In the initial fermentation stage after constructing the mixed material pile, the easily degradable organic matter inside the mixture decomposes under the metabolic action of aerobic microorganisms, generating volatile fatty acids and other organic acids. The 30%-35% homologous tobacco straw biochar added in step S105 forms alkaline ash and oxygen-containing functional groups on its surface during pyrolysis, resulting in an overall weakly alkaline pH. The homologous tobacco straw biochar undergoes an acid-base neutralization reaction with the organic acids generated inside the mixed material, maintaining the pH of the mixed material pile between 6.5 and 8.0. This pH range of 6.5-8.0 avoids the toxic inhibition of microorganisms caused by the accumulation of organic acids, maintaining the metabolic activity of carbon-degrading microorganisms such as cellulose-degrading bacteria.

[0031] S108: Early Microbial Colonization. The initial addition of homologous tobacco straw biochar provides a space for the colonization and attachment of native carbon-degrading microorganisms in the mixture through its physical pores. These microorganisms attach to the pores of the homologous tobacco straw biochar, forming a microbial film. This porous colonization environment promotes the secretion of cellulase, ligninase, and dehydrogenase. The enrichment of cellulase, ligninase, and dehydrogenase accelerates the biochemical decomposition of recalcitrant straw carbon components in the mixture, providing precursors for the subsequent synthesis of the humic carbon skeleton.

[0032] S109: Pore Blockage Control. Limiting the initial addition to 30%-35% of the total weight of the homologous tobacco straw biochar is to prevent premature and complete blockage of carbon adsorption pores during the early stages of fermentation. In the initial heating phase of mixed material fermentation, the rapid decomposition of easily degradable organic matter generates water-soluble small-molecule organic matter and microbial metabolic colloidal substances. Limiting the initial addition of homologous tobacco straw biochar ensures that water-soluble small-molecule organic matter and microbial metabolic colloids occupy only a small portion of the adsorption sites on the homologous tobacco straw biochar. The remaining 65%-70% of the homologous tobacco straw biochar is reserved for deeper injection during the subsequent high-temperature fermentation period, ensuring that unblocked physical pores remain for adsorption and retention during the peak release of soluble organic carbon.

[0033] After completing the pore blockage control in step S109, the mixture enters the aerobic fermentation start-up stage. The operation and biochemical reaction process of the aerobic fermentation start-up stage are divided into steps S201 to S204.

[0034] S201: Forced ventilation system activated. Activate the forced ventilation system installed at the bottom of the trough-type aerobic fermentation reaction system to introduce outside air into the mixture pile. Set the ventilation rate of the forced ventilation system to 0.05-0.2 m / s². 3 / (m 3 (min). 0.05-0.2m 3 / (m 3 A ventilation rate of (·min) can meet the oxygen demand for aerobic microorganism reproduction without removing excessive bioheat from the mixture pile. For the duct layout and fan selection of the forced ventilation equipment, those skilled in the art can refer to conventional trough composting production lines. The duct layout and fan selection are well-known technologies in this field and will not be elaborated further here.

[0035] S202: Pore oxygen concentration control. During the process of introducing outside air into the mixture stockpile, the pore oxygen volume concentration inside the stockpile is monitored in real time by an oxygen sensor inserted inside the stockpile. The ventilation rate of the forced ventilation system is adjusted based on the data from the oxygen sensor to maintain the pore oxygen volume concentration between 10% and 15%. If the pore oxygen volume concentration is below 10%, the bottom layer of the mixture will experience denitrification and methanogenesis due to oxygen deficiency, increasing greenhouse gas emissions. If the pore oxygen volume concentration is above 15%, excessive air penetration into the mixture stockpile will cause physical cooling, preventing heat accumulation inside the stockpile.

[0036] S203: Real-time monitoring of core temperature. During the operation of activating the forced ventilation equipment, the temperature sensor inserted into the mixture pile is turned on, and the core temperature change curve of the mixture pile is continuously recorded. The probe end of the temperature sensor is controlled to be located within a depth range of 0.5-0.8m from the top surface of the mixture pile to accurately obtain the core temperature. The core temperature change curve recorded by the temperature sensor is used to quantify the biochemical metabolic intensity of carbon-degrading microorganisms and to provide numerical triggering conditions for subsequent deep biochar injection operations during the high-temperature fermentation period.

[0037] S204: Microbial Community Succession and Heating. Under the combined effects of oxygen supply from the forced ventilation system and the organic acid neutralization reaction in step S107, thermophilic aerobic bacteria and fungi proliferate within the mixture. Thermophilic microorganisms degrade water-soluble carbohydrates and proteins in the mixture, releasing bioheat. The accumulated bioheat raises the core temperature of the mixture to above 40°C, and the microecological community undergoes a succession from thermophilic to thermophilic microorganisms. The fermentation metabolism of the thermophilic microorganisms causes the core temperature to continue to rise, and the mixture transitions into the high-temperature fermentation phase.

[0038] After completing the transition of the mixture to the high-temperature fermentation stage in step S204, the mixture enters the high-temperature fermentation stage. During this stage, deep biochar injection is performed. The triggering mechanism for this deep biochar injection operation is as follows: S301: High-Temperature Initiation Monitoring. Based on the core temperature change curve continuously recorded by the temperature sensor in step S203, monitor the core temperature of the mixture. When the core temperature of the mixture reaches 60℃ or above, record the high-temperature initiation time. A core fermentation temperature of 60℃ or above is a physical indicator of the biochemical degradation of hemicellulose and some cellulose within the mixture. Within the temperature range of 60℃ or above, thermophilic microorganisms secrete extracellular enzymes, promoting the decomposition of solid organic matter within the mixture into free soluble organic carbon and soluble organic nitrogen.

[0039] S302: Duration Threshold Determination. Based on the high-temperature initiation time, calculate the duration for which the core temperature is maintained at 60℃ or higher. Determine if the duration reaches the range of 48-72 hours. A high-temperature duration of 48-72 hours allows the mixture to accumulate heat to kill pathogens and weed seeds, ensuring the compost meets harmless hygiene standards. After 48-72 hours of high-temperature decomposition, the physical pores of the initially added homologous tobacco straw biochar in step S105 are filled with water-soluble small molecules and microbial metabolic colloids produced in the early stages of fermentation, reaching adsorption saturation. Because the initially added homologous tobacco straw biochar loses its adsorption capacity for newly generated soluble organic carbon, the soluble organic carbon accumulated inside the mixture faces the risk of being mineralized into carbon dioxide gas by aerobic microorganisms and released.

[0040] S303: Temperature Drop Inflection Point Trigger Determination. Under the condition that the core temperature is maintained for 48-72 hours, the decreasing trend of the core temperature is continuously evaluated along the time axis. When the core temperature change curve shows a temperature drop of 1°C or more within 6 consecutive hours, it is confirmed that the peak stage of carbon mineralization heat production in the mixture has ended, meeting the triggering conditions for deep injection of remaining homologous tobacco straw biochar. A temperature drop of more than 1°C for 6 consecutive hours indicates that the consumption of readily degradable carbon sources within the mixture exceeds the generation of readily degradable carbon sources, and the fermentation heat production rate of thermophilic microorganisms is lower than the heat dissipation rate of the mixture to the external environment. Physical intervention in the mixture during the fermentation stage that meets the temperature drop characteristics avoids damage to the high-temperature fermentation micro-ecological community and meets the process requirement of introducing unblocked physical pores into the mixture to retain soluble organic carbon.

[0041] After completing the deep injection of biochar from the remaining homologous tobacco straw in stage S300, the peak stage of carbon mineralization and heat generation in the mixture subsided, and the mixture entered the cooling and maturation period. The operations during the cooling and maturation period, as well as the microecological evolution process, are divided into steps S401 to S404.

[0042] S401: Segmented Turning and Moisture Content Adjustment. After the deep injection operation is completed and the mixture has remained for 24-48 hours, mechanical turning is performed on the mixture according to a preset turning cycle. The mechanical turning cycle is set to once every 5-7 days. Since the homologous tobacco straw biochar injected in the deep injection has completed the adsorption and retention of soluble organic carbon, mechanical turning at this time will not cause a large amount of carbon gas to escape. The mechanical turning operation introduces external oxygen into the mixture, breaking up any possible anaerobic micro-zones and maintaining the aerobic metabolic environment of the microbial community during the cooling period. During the mechanical turning operation, the moisture content of the mixture is monitored. If the moisture content of the mixture is lower than 40%, it is adjusted to between 40% and 50% by spraying water. For the turning equipment used in mechanical turning, those skilled in the art can use a conventional trough-type turning machine. The mechanical structure of the turning equipment is well-known in the art and will not be described in detail here.

[0043] S402: Humic Synthesis and Carbon Skeleton Stabilization. During the cooling and maturation periods, the core temperature of the mixture gradually decreases to below 40°C. Under mesophilic aerobic conditions, lignin-degrading bacteria in the mixture utilize the previously retained soluble organic carbon and soluble organic nitrogen for metabolic activities. These bacteria convert recalcitrant straw carbon into humic precursors. Catalyzed by oxygen-containing functional groups on the surface of the homologous tobacco straw biochar, these humic precursors undergo condensation and polymerization reactions, forming stable humic carbon with aromatic structures. The formation of stable humic carbon increases the degree of polymerization of organic matter molecules, converting free carbon into fixed carbon.

[0044] S403: Fermentation Endpoint Detection and Maturity Determination. Continuous monitoring of the physicochemical and biological indicators of the mixture is used to determine the end point of the fermentation process. When the temperature difference between the core of the mixture and the ambient temperature is within 2℃, the overall carbon-to-nitrogen ratio of the mixture decreases to between 15:1 and 20:1, and the seed germination index is ≥80%, the mixture is considered to have reached full maturity. Full maturity signifies the cessation of the biochemical decomposition process within the mixture, and the stabilization of the physicochemical properties of the compost system. The mixture that has reached full maturity is the final product of the carbon sequestration and emission reduction tobacco straw-sheep manure compost composition.

[0045] S404: Product Discharge and Carbon Sequestration Application. The fully decomposed compost is removed from the trough-type aerobic fermentation system. The discharged compost is directly applied to agricultural soils as a soil amendment substrate. The stable humic carbon and homologous tobacco straw biochar within the compost possess anti-degradation capabilities in the soil microecological environment. Applying the compost to the soil reduces the mineralization and decomposition rate of soil microorganisms, thus achieving the sequestration of organic carbon in agricultural solid waste and greenhouse gas emission reduction.

[0046] Example 1 A base compost mixture with a total dry matter weight of 100 parts and homologous tobacco straw biochar with a total weight of 10 parts were prepared. Tobacco straw was collected and inorganic impurities removed, then crushed using a mechanical crusher to obtain tobacco straw aggregate with a particle size of 15 mm. Tobacco straw from the same source was placed in an anaerobic pyrolysis furnace and heated to 450°C at a heating rate of 10°C per minute, and held at 450°C for two hours. After pyrolysis, the mixture was cooled to room temperature under anaerobic conditions, and particles with a particle size of 2 mm were collected by crushing and sieving as homologous tobacco straw biochar. Fresh sheep manure was collected and air-dried to reduce its moisture content to 65%. The tobacco straw aggregate and sheep manure were fed into a twin-shaft mixer and mixed, adjusting the overall carbon-to-nitrogen ratio of the base compost mixture to 25:1 and the overall moisture content of the base compost mixture to 55%. During the mixing operation of the twin-shaft mixer, three parts of homologous tobacco straw biochar were added, accounting for 30% of the total weight of ten parts of homologous tobacco straw biochar.

[0047] After the mixture was prepared, it was transported to the fermentation tank and stacked to a height of 1.2 meters. Forced ventilation was activated, with a ventilation rate of 0.1 cubic meters of air per cubic meter of mixture per minute, maintaining an oxygen volume concentration of 12% within the mixture pile. The core temperature was continuously recorded using a temperature sensor. When the core temperature reached 60 degrees Celsius and remained there for 48 hours, and the temperature sensor recorded a temperature drop of 1 degree Celsius over 6 consecutive hours, the deep-layer injection triggering conditions for the high-temperature period were met. The remaining 7 portions of homologous tobacco straw biochar were pre-wetted and injected into the high-temperature zone of the mixture using a deep rotary tillage device. After injection and a 24-hour settling period, the mechanical turning cycle was set to once every five days. During the cooling and composting periods, the mixture was considered fully composted when the temperature difference between the core and ambient temperatures was within 1 degree Celsius, the overall carbon-to-nitrogen ratio decreased to 15:1, and the seed germination index reached 85%. The mixture was then removed from the fermentation tank to obtain the final compost product of Example 1.

[0048] Example 2 A base compost mixture with a total dry matter weight of 100 parts and a homologous tobacco straw biochar with a total weight of 15 parts were prepared. Tobacco straw was collected and aggregated with a particle size of 25 mm. The tobacco straw from the same source was placed in an anaerobic pyrolysis furnace and heated to 550°C at a heating rate of 5°C per minute, and held at 550°C for three hours. The pyrolysis products were cooled to room temperature under anaerobic conditions, and the homologous tobacco straw biochar with a particle size of 4 mm was collected after crushing and sieving. Sheep manure dried to a moisture content of 60% was mixed with the tobacco straw aggregate to adjust the overall carbon-to-nitrogen ratio of the base compost mixture to 30:1, and the overall moisture content of the base compost mixture was adjusted to 65%. During the mixing process, 5.25 parts of homologous tobacco straw biochar were added, accounting for 35% of the total weight of the 15 parts of homologous tobacco straw biochar.

[0049] The mixture was transported to the fermentation tank and stacked to a height of 1.5 meters. Forced ventilation was activated, with a ventilation rate of 0.15 cubic meters of air per cubic meter of mixture per minute, maintaining an oxygen volume concentration of 15% within the mixture pile. When the core temperature of the mixture reached 65 degrees Celsius and remained there for 72 hours, and the temperature sensor recorded a temperature drop of 1.5 degrees Celsius over six consecutive hours, the deep-layer injection triggering conditions for the high-temperature period were met. The remaining 9.75 parts of homologous tobacco straw biochar were pre-wetted and injected into the high-temperature zone of the mixture using a deep rotary tillage device. After injection and a 48-hour settling period, the mechanical turning cycle was set to once every seven days. During the cooling and composting periods, when the temperature difference between the core of the mixture and the ambient temperature is within 0.5 degrees Celsius, the overall carbon-to-nitrogen ratio decreases to 18:1, and the seed germination index reaches 90%, the mixture is considered to have reached complete composting. The mixture is then removed from the fermentation tank to obtain the final compost product of Example 2.

[0050] Comparative Example 1 provides a basic composting method without adding homologous tobacco straw biochar to demonstrate the necessity of homologous tobacco straw biochar in carbon sequestration and emission reduction processes.

[0051] Comparative Example 1: Compared with Example 1, the difference is that no homologous tobacco straw biochar is added in the mixture preparation operation, the basic pile mixture is only composed of tobacco straw aggregate and sheep manure, and the pre-wetting treatment and deep injection operation for homologous tobacco straw biochar are not performed during the high temperature fermentation period. All other aspects are the same.

[0052] Comparative Example 2 provides a composting method using a one-time addition process to verify the technical effectiveness of the segmented addition process in overcoming the problem of premature clogging of physical pores.

[0053] Comparative Example 2: Compared with Example 1, the difference is that in the preparation of the mixture, all 10 parts of homologous tobacco straw biochar are added into the twin-shaft mixer at once, and the deep injection operation for homologous tobacco straw biochar is not performed after the high temperature fermentation period meets the triggering conditions. All other aspects are the same.

[0054] Comparative Example 3 provides a composting method that directly adds dry biochar using the traditional turning and throwing method during the high-temperature fermentation period, highlighting the ingenuity of pre-wetting treatment and deep rotary tillage injection in preventing thermal shock and avoiding instantaneous escape of carbon gas.

[0055] Comparative Example 3: Compared with Example 1, the difference is that after the high-temperature fermentation period meets the triggering conditions, the remaining 7 portions of homologous tobacco straw biochar are not pre-wetted. Instead, a mechanical turner is used to directly turn and mix the 7 portions of homologous tobacco straw biochar in a dry state into the mixture, replacing the deep injection operation of the deep rotary tillage equipment. All other aspects are the same.

[0056] Comparative Example 4 provides a composting method with an addition of biochar from the same source of tobacco straw exceeding the specified range, used to verify that the addition range of 5%-20% is the critical numerical range for achieving carbon fixation and microecological balance.

[0057] Comparative Example 4: Compared to Example 1, the difference lies in the preparation of 25 parts by weight of homologous tobacco straw biochar. In the mixture preparation process, 7.5 parts by weight of homologous tobacco straw biochar were added, accounting for 30% of the total weight of the 25 parts. After the triggering conditions were met during the high-temperature fermentation period, the remaining 17.5 parts by weight of homologous tobacco straw biochar were pre-wetted and injected into the high-temperature zone of the mixture; all other steps were the same.

[0058] Test Example 1 To verify the technical effects of Examples 1 and 2, and to compare and analyze them with Comparative Examples 1 to 4, a multi-dimensional carbon cycle effect verification was performed on the fermentation process and final product of Examples 1, 2, and the four comparative examples.

[0059] Throughout the aerobic fermentation cycle, gases released from the fermentation tank surface were collected daily at set times using static dark-box gas chromatography. The collected gas samples were injected into the gas chromatograph to determine the concentrations of carbon dioxide and methane. The daily emissions were summed throughout the fermentation cycle to obtain the cumulative carbon dioxide and methane emission fluxes. The mixture was weighed and sampled before fermentation started and after complete fermentation. The total carbon mass fraction in the solid samples was determined using an elemental analyzer, and the total carbon retention rate was calculated based on the total dry matter mass before and after fermentation. For the specific operating procedures of the gas chromatograph and elemental analyzer, those skilled in the art can refer to conventional analytical chemistry experimental standards; the instrument operating procedures are well-known in the field and will not be elaborated further here.

[0060] During the high-temperature fermentation and fermentation maturation stages, core layer samples of the mixed materials were collected periodically. The core layer samples were mixed with deionized water at a solid-liquid ratio of 1:10 and extracted by shaking on a reciprocating shaker for 2 hours. The extracted suspension was then filtered through a 0.45-micron pore size filter membrane. The filtrate was placed in a total organic carbon analyzer to determine the soluble organic carbon content within the filtrate.

[0061] The filtrate sample prepared by the aforementioned filtration was extracted and placed in a UV-Vis spectrophotometer. The absorbance of the filtrate at a wavelength of 254 nm was measured, and the absorbance value was divided by the concentration of dissolved organic carbon in the filtrate sample to calculate the UV aromatization index. The UV aromatization index is used to quantify the degree of aromatic ring polymerization and molecular structural stability of the humic carbon skeleton in compost products. Simultaneously, a Fourier transform infrared spectroscopy was used to scan the functional groups of the fully decomposed mixture solid sample to determine the conversion ratio of aliphatic carbon to aromatic carbon.

[0062] Samples of the mixture were extracted during the warming and high-temperature stages of fermentation. Cellulase activity in the samples was determined using the 3,5-dinitrosalicylic acid colorimetric method. The highest cellulase activity value during the fermentation cycle was recorded as the peak cellulase activity. Peak cellulase activity reflects the early decomposition ability of microorganisms in the microecological environment for recalcitrant straw carbon components.

[0063] Following the above testing procedures, the test data for Example 1, Example 2, and Comparative Examples 1 to 4 are summarized. The test data is summarized in Table 1:

[0064] Table 1. Multidimensional characterization test data of carbon cycle in the examples and comparative examples. Based on the test data in Table 1 and the innovative mechanism of the composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar, the following conclusions are drawn: Comparing the test data of Example 1 and Comparative Example 1, it can be concluded that introducing homologous tobacco straw biochar into the base mixture of tobacco straw and sheep manure can increase the total carbon retention rate from 38.54% to over 60% and significantly reduce the cumulative emission flux of carbon dioxide and methane. The addition of homologous tobacco straw biochar significantly increased the peak activity of cellulase, and this increase in cellulase activity verifies the high degree of matching between the physicochemical properties of the homologous material and the microecological environment of the base mixture. This matched microecological environment avoids the toxic inhibition of carbon-degrading enzymes by heterologous biochar and promotes the decomposition of recalcitrant straw carbon.

[0065] Comparing the test data of Example 1 and Comparative Example 2, it can be concluded that the segmented addition process has significant technical advantages. Comparative Example 2 uses a one-time addition method, where water-soluble small-molecule organic matter and microbial metabolic colloids generated in the early stage of fermentation cause premature blockage of the physical pores of the homologous tobacco straw biochar. During the carbon mineralization explosion stage at high temperature during fermentation, the one-time addition of homologous tobacco straw biochar loses its adsorption capacity, and a large amount of soluble organic carbon is converted into greenhouse gases and emitted, resulting in a cumulative carbon dioxide emission flux as high as 178.65 kg / t. Example 1 reserves 65% to 70% of the homologous tobacco straw biochar for deep injection during the high temperature stage of fermentation, using the unblocked physical pores to precisely retain soluble organic carbon, reducing the soluble organic carbon content at the maturity stage to 12.41 g / kg. The retained soluble organic carbon participates in subsequent condensation reactions, transforming into stable humic carbon with an aromatic structure, thereby achieving a significant improvement in the UV aromaticity index. The increase in the UV aromatization index proves that the staged addition process can promote the conversion of free carbon to stationary carbon.

[0066] Comparing the test data of Example 1 and Comparative Example 3, it can be concluded that the injection operation using pre-wetting treatment combined with deep rotary tillage equipment during the high-temperature fermentation period is a key technical action for reducing greenhouse gas emissions. Comparative Example 3 directly added dry, homologous tobacco straw biochar using traditional mechanical turning and turning methods. The dry carbon particles triggered a thermal shock to the microecological environment of the mixture, and the mechanical turning action introduced excessive instantaneous airflow into the mixture, causing a large amount of carbon dioxide and methane gas trapped inside to escape to the outside. The pre-wetting deep injection operation replenishes physical pores without disrupting the in-situ microecological structure during the high-temperature period, achieving synergistic carbon sequestration and emission reduction.

[0067] Comparing the test data of Examples 1 and 2 with Comparative Example 4, it can be concluded that there is a strict critical effect in the amount of homologous tobacco straw biochar added. When the added amount exceeds the upper limit of 20 parts and reaches 25 parts, the excessive amount of homologous tobacco straw biochar disrupts the carbon-nitrogen ratio balance and liquid-phase mass transfer balance suitable for the survival of carbon-degrading microorganisms within the mixture. This microecological imbalance leads to a decrease in cellulase activity, and the total carbon retention rate shows a rebound downward trend, proving that the dry matter weight ratio of 5 to 20 parts is the core parameter range for achieving the optimal carbon sequestration and emission reduction effect of the composting system. The test data listed in Table 1 provide sufficient implementation verification support for the component ratios, fermentation condition judgment thresholds, and core operational actions described in the claims.

[0068] Test Example 2 Carbon dynamic transformation and micro-ecological succession testing.

[0069] The mixture from Example 1 was used as the experimental group, and the mixture from Comparative Example 2 was used as the control group. Day 3 of fermentation was defined as the time point before the high-temperature injection, day 5 of fermentation as the time point after the high-temperature injection, day 15 of fermentation as the cooling period, and day 30 of fermentation as the maturation period. In-situ sampling and online monitoring were conducted on the fermentation tank at these four time points: day 3, day 5, day 15, and day 30 of fermentation.

[0070] The carbon dioxide and methane emission fluxes on the surface of the fermenter were continuously measured using a tunable semiconductor laser absorption spectroscopy system. Solid-phase samples of the mixture were extracted at corresponding time points, and the weight-average molecular weight of water-soluble organic matter was determined using gel permeation chromatography. Weight-average molecular weight was used to assess the conversion rate of free small carbon molecules to polymerized large carbon molecules. Total deoxyribonucleic acid (DNA) was simultaneously extracted from the solid-phase samples of the mixture, and the relative abundance of methanogenic bacteria in the microbial community was analyzed using high-throughput sequencing technology.

[0071] The test data of the experimental group and the control group at different fermentation stages are summarized in Table 2.

[0072]

[0073] Table 2. Dynamic test data on carbon flux and microecological evolution before and after deep injection during the high-temperature period. Based on the test data in Table 2 and the regulatory mechanism of staged addition of homologous biochar, the following conclusions are drawn: In the control group, carbon dioxide and methane emission fluxes peaked on day 5 of fermentation, and the relative abundance of methanogens increased to 2.54%. The homologous tobacco straw biochar added in the control group at one time reached adsorption saturation in the early stages of fermentation. Pore blockage prevented the homologous tobacco straw biochar in the control group from intervening in the high-temperature carbon mineralization reaction. The bottom mixture consumed oxygen, creating an anaerobic microenvironment that promoted the proliferation of methanogens and the release of methane.

[0074] After performing deep-injection on day 3 of fermentation, the carbon dioxide and methane emission fluxes decreased on day 5. Pre-wetted homologous tobacco straw biochar, introduced into the high-temperature zone of the mixture, altered the physicochemical state of the gas-liquid-solid three-phase interface. Deep rotary tillage, combined with the unblocked porous structure, broke down the anaerobic microzones within the mixture, inhibiting the metabolic activity of methanogenic bacteria and reducing their relative abundance from 1.83% to 0.61%. Supplementing the mixture with unblocked homologous tobacco straw biochar can interrupt the methane formation pathway and reduce greenhouse gas emission fluxes.

[0075] The weight-average molecular weight of water-soluble organic matter in the experimental group increased after the injection of homologous tobacco straw biochar, reaching 3215 Da at the maturity stage. The oxygen-containing functional groups on the surface of the homologous tobacco straw biochar formed chemical bonds with free small-molecule organic carbon. After trapping small-molecule carbon, the homologous tobacco straw biochar underwent condensation polymerization under the catalysis of microbial enzymes, using physical pores as reaction centers. In the control group, due to the lack of unblocked adsorption sites, the free small-molecule carbon underwent mineralization and decomposition, resulting in a weight-average molecular weight of 2108 Da for water-soluble organic matter at the maturity stage. The difference in weight-average molecular weight between the experimental and control groups demonstrates that the segmented addition of homologous tobacco straw biochar altered the carbon transformation pathway, promoting the conversion of free carbon sources into humic precursors with increased polymerization, thus achieving structural stability and physical sequestration of organic carbon.

[0076] To verify the effect of deep injection during the high-temperature fermentation period on the evolution of the carbon skeleton of humic substances and the stability of carbon fixation in the mixture, the microscopic molecular structure of humic substances was analyzed.

[0077] The mixture of Example 1, Comparative Example 1, and Comparative Example 2 at the 30th day of fermentation and maturation was used as the test sample.

[0078] The solid sample of the mixture was mixed with deionized water at a solid-liquid ratio of 1:10 and extracted by shaking in a constant temperature shaker at room temperature for 24 hours. The mixture was centrifuged, and the supernatant was filtered through a 0.45-micron pore membrane to obtain the soluble organic matter extract.

[0079] The soluble organic matter extract was scanned using a three-dimensional fluorescence spectrometer to obtain excitation-emission matrix spectral data. Parallel factor analysis was used to decompose the excitation-emission matrix spectral data into components, and the relative proportion of humic acid-like components in the total fluorescent components was calculated.

[0080] The absorbance of the soluble organic matter extract was measured by scanning with a UV-Vis spectrophotometer to obtain the absorbance at a specific wavelength, and the UV absorption wavelength ratio was calculated.

[0081] High-resolution mass spectrometry (HMS) analysis of the dissolved organic matter extract was performed using Fourier transform ion cyclotron resonance (FTIR) mass spectrometry. Based on the molecular formula derived from the mass spectrometry data, the modified aromatic index and the number of equivalent double bonds were calculated. The modified aromatic index and the number of equivalent double bonds are used to reflect the degree of aromatic ring condensation in the carbon skeleton at the molecular level.

[0082] The solid samples of the mixture were dehydrated using a freeze dryer. The dehydrated solid samples were then scanned using Fourier transform infrared spectroscopy (FTIR), with wavenumbers measured at 1630 cm⁻¹. -1 The absorption peak intensity and wavenumber of the aromatic carbon-carbon double bond at 2920 cm⁻¹ -1 The ratio of the absorption peak intensities of aliphatic C-H bonds at a given location. This ratio is used to assess the proportion of aromatic structures in the organic carbon skeleton.

[0083] Parallel factor analysis (PARAFAC) was used to decompose the three-dimensional fluorescence spectral data and calculate the relative proportion of humic acid-like components in the total fluorescent components. Absorbance at specific wavelengths was measured using UV-Vis spectroscopy, and combined with Fourier transform infrared spectroscopy (FTIR) and high-resolution mass spectrometry (FTICR-MS) data, the microscopic molecular characteristic indices of the solid and liquid extracts from the mixture were obtained.

[0084] The microscopic characterization test data of Example 1, Comparative Example 1, and Comparative Example 2 are summarized in Table 3:

[0085] Table 3. Spectroscopic and mass spectrometric microscopic characterization data of humus in the mixture during fermentation and composting period. Based on the test data in Table 3 and the regulatory mechanism of staged application of biochar from the same source tobacco straw, the following conclusions are drawn: In Example 1, the proportion of humic acid-like fluorescent components reached 68.42%, and the UV absorption wavelength ratio decreased to 3.14. Comparison of three-dimensional fluorescence and UV-Vis spectral data showed that deep injection of unblocked homologous tobacco straw biochar during the high-temperature fermentation period retained soluble organic matter to participate in subsequent reactions, promoting the conversion of low-molecular-weight free carbon into high-molecular-weight humic acid-like components. Fourier transform infrared spectroscopy and high-resolution mass spectrometry data showed that the modified aromatic index and equivalent double bond number of Example 1 were significantly higher than those of the comparative example. Multidimensional spectral and mass spectrometry data jointly demonstrated that the segmented addition of homologous tobacco straw biochar retained chemical reaction sites, promoting the conversion of linear aliphatic carbon into aromatic carbon. The increased degree of aromatic ring condensation enhanced the anti-degradation ability of humic molecules, achieving chemical sequestration of organic carbon. Test Example 4 Evolution of physicochemical indicators and verification test of compost maturity.

[0086] The mixtures of Examples 1, 2, and Comparative Examples 1 to 4 were used as test subjects. Sampling and in-situ monitoring were carried out during the early fermentation stage, the high-temperature stage, and the maturation stage.

[0087] The highest core temperature during the fermentation cycle was continuously recorded using a temperature sensor. Solid phase samples from the maturation stage were extracted, mixed with deionized water, and shaken. The pH was measured using a pH meter, and the conductivity was measured using a conductivity meter. The soluble organic nitrogen content was determined using a total organic carbon / total nitrogen analyzer. The total nitrogen content was determined using an elemental analyzer, and the final carbon-to-nitrogen ratio was calculated based on the total carbon data. Aqueous extracts from the maturation stage samples were used for seed germination tests, and the seed germination index was calculated.

[0088] The physicochemical indicators and final maturity data of each group during the fermentation process are summarized in Table 4:

[0089] Table 4. Evolution of culinary indices and final decomposition test data of the mixture Based on the test data in Table 4 and the physicochemical effects of the same-origin tobacco straw biochar, the following conclusions are drawn: The highest core temperatures of both Examples 1 and 2 exceeded 60°C and met the duration requirements, demonstrating that the basic compost mixture possessed sufficient fermentation heat energy at the set carbon-nitrogen ratio. The pH value during the maturation period of the examples remained stable between 7.6 and 7.8, proving that the homologous tobacco straw biochar added in the early stages of fermentation effectively neutralized organic acids and maintained acid-base balance. The total nitrogen content during the maturation period of the examples reached over 24.5 g / kg, while the soluble organic nitrogen content decreased to 145.2 mg / kg or below. The increase in total nitrogen content and the decrease in soluble organic nitrogen demonstrate that the biochar added in stages during the high-temperature period retained the free nitrogen source, reducing ammonia volatilization and nitrogen loss.

[0090] In the examples, the electrical conductivity was below the defined safety threshold, the seed germination index exceeded 80%, and the carbon-nitrogen ratio decreased to the range of 15:1 to 20:1. Comparative Example 1 lacked intervention from homologous tobacco straw biochar, resulting in a higher carbon-nitrogen ratio due to total nitrogen loss, and the seed germination index did not reach the complete decomposition standard. The comprehensive test data in Table 4 demonstrates that the parameter combination and segmented addition steps defined in this invention can eliminate the phytotoxicity of the product, achieving harmless treatment of agricultural solid waste and high-quality nitrogen and fertilizer retention.

[0091] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar, characterized in that, The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar relies on a trough-type aerobic fermentation reaction system and includes the following steps: S100, Material Mixing and Initial Biochar Addition: Tobacco straw and sheep manure are mixed to prepare a basic compost mixture with a carbon-to-nitrogen ratio of 25:1 to 30:1 and a moisture content of 55% to 65%; In the preparation of the basic compost mixture, 30% to 35% of the total weight of the homologous tobacco straw biochar is added; Based on dry matter weight, the basic compost mixture is 100 parts, and the homologous tobacco straw biochar is 5 to 20 parts; S200, Aerobic Fermentation Start-up: Place the mixture of the same source tobacco straw biochar into a trough reactor to start fermentation; turn on the ventilation and aeration equipment of the trough reactor to continuously supply oxygen to the mixture, so that the mixture enters an aerobic heating state; S300, High-Temperature Biochar Injection: Triggering conditions are set by monitoring the temperature change curve of the mixed material core; when the core temperature of the mixed material reaches 60°C or above and is maintained for 48 to 72 hours, and the temperature drops by 1°C or more for 6 consecutive hours, a follow-up injection operation is triggered; after the triggering conditions are met, the remaining 65% to 70% of the homologous tobacco straw biochar is pre-wetted, and the pre-wetted homologous tobacco straw biochar is injected into the high-temperature zone of the mixed material through a deep rotary tillage device; S400, Fermentation and Discharge: After the injection operation is completed, the mixture enters the cooling and composting period; the mixture is turned over in stages according to the set turning cycle and the moisture content of the mixture is controlled until the compost product is mature.

2. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 1, characterized in that, Before the mixing of materials and the initial addition of biochar, the pretreatment of the basic raw materials and the preparation process of biochar from the same source of tobacco straw include the following steps: Preparation of tobacco straw aggregate: Collect the tobacco straw and remove the inorganic impurities mixed in the tobacco straw; send the tobacco straw after removing the inorganic impurities into a mechanical crusher for mechanical crushing; screen the crushed tobacco straw through a vibrating screen to intercept and select crushed straw with a particle size in the range of 10 mm to 30 mm as tobacco straw aggregate; Pyrolysis of biochar from the same source as the tobacco straw: tobacco straw from the same source as the tobacco straw is taken, and the uncrushed or crushed tobacco straw is placed in an anaerobic pyrolysis furnace for pyrolysis and carbonization; the pyrolysis parameters of the anaerobic pyrolysis furnace are set as follows: the inside of the anaerobic pyrolysis furnace is heated to the target pyrolysis temperature of 400°C to 600°C at a heating rate of 5°C to 15°C per minute, and the temperature is kept constant at the target pyrolysis temperature for 2 to 4 hours; Grading of homologous tobacco straw biochar: The homologous tobacco straw biochar produced by pyrolysis is cooled to room temperature under anaerobic conditions; the cooled homologous tobacco straw biochar is crushed using a crusher; the crushed homologous tobacco straw biochar is graded through a mesh screen, and carbon particles with a particle size in the range of 1 mm to 5 mm are collected as homologous tobacco straw biochar.

3. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 2, characterized in that, The pretreatment of the basic raw materials also includes: Sheep manure moisture content adjustment: Test the initial moisture content of fresh sheep manure; if the initial moisture content of the fresh sheep manure exceeds 75%, add drying auxiliary material to the fresh sheep manure for dehydration treatment, or reduce the moisture content of the fresh sheep manure to between 60% and 70% by natural air drying. The material mixing and initial biochar addition specifically involve: feeding the tobacco straw aggregate, treated sheep manure, and a portion of the homologous tobacco straw biochar into a twin-shaft mixer for mixing; during the mixing operation, adjusting the overall moisture content of the mixture in the twin-shaft mixer to 55% to 65% by spraying water or adding dried tobacco straw aggregate.

4. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 1, characterized in that, In step S100, after material mixing and initial biochar addition, the process enters the pile building and early fermentation microecological construction stage, including: Material stacking: The mixed output materials are transported to the fermentation tank of the trough-type aerobic fermentation reaction system, and the mixed materials are stacked to form a material pile; the stacking height of the material pile is controlled to be 1.2 meters to 1.5 meters; Organic acid neutralization reaction: The homologous tobacco straw biochar undergoes an acid-base neutralization reaction with the organic acids generated inside the mixture, maintaining the pH of the mixture pile between 6.5 and 8.

0.

5. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 1, characterized in that, The S200 aerobic fermentation start-up includes: Forced ventilation equipment startup: Start the forced ventilation equipment laid at the bottom of the trough-type aerobic fermentation reaction system to fill the mixture pile with outside air; set the ventilation rate of the forced ventilation equipment to 0.05 to 0.2 cubic meters of air per cubic meter of mixture per minute; Pore ​​oxygen concentration control: The pore oxygen volume concentration inside the mixture pile is monitored in real time by an oxygen sensor inserted inside the mixture pile; the ventilation rate of the forced ventilation equipment is adjusted according to the data fed back by the oxygen sensor so that the pore oxygen volume concentration is maintained between 10% and 15%.

6. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 1, characterized in that, During the S300 high-temperature biochar injection phase, the operation of monitoring the core temperature change curve of the mixed feedstock includes: Real-time core temperature monitoring: The temperature sensor inserted into the mixture material pile is turned on, and the core temperature change curve of the mixture material pile is continuously recorded; the detection end of the temperature sensor is controlled to be located within a depth range of 0.5 meters to 0.8 meters from the top surface of the mixture material pile to accurately obtain the core temperature.

7. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 1, characterized in that, In the S300 process, during the high-temperature biochar injection, the determination process for setting trigger conditions is as follows: High-temperature initiation monitoring: Based on the continuously recorded core temperature change curve, monitor the core temperature of the mixture; when the core temperature of the mixture reaches 60°C or above, record the high-temperature initiation time; Duration threshold determination: Based on the high temperature onset time, calculate the duration for which the core temperature is maintained at or above 60°C; determine whether the duration reaches the range of 48 to 72 hours. Cooling inflection point trigger determination: Under the condition that the core temperature is maintained for 48 to 72 hours, the decreasing trend of the core temperature is continuously evaluated along the time axis; when the core temperature change curve shows the data characteristic that the temperature decrease reaches or exceeds 1°C within 6 consecutive hours, the trigger condition is met.

8. The composting carbon sequestration and emission reduction method based on the staged addition of homologous biochar according to claim 1, characterized in that, The S400 process, including fermentation, composting, and discharge, includes: Segmented turning and moisture content adjustment: After the injection operation is completed and the mixture remains for 24 to 48 hours, the mixture is mechanically turned according to a preset turning cycle; the turning cycle is set to once every 5 to 7 days; during the mechanical turning operation, the moisture content of the mixture is monitored; if the moisture content of the mixture is lower than 40%, the moisture content of the mixture is adjusted to between 40% and 50% by spraying water.

9. A method for composting, carbon sequestration, and emission reduction based on the staged addition of homologous biochar, as described in claim 8, is characterized in that... The S400 process, including fermentation, composting, and discharging, also includes: Fermentation endpoint detection and maturity determination: Continuously monitor the physicochemical and biological indicators of the mixture; when the temperature difference between the core of the mixture and the ambient temperature is within 2℃, the overall carbon-nitrogen ratio of the mixture decreases to between 15:1 and 20:1, and the seed germination index is greater than or equal to 80%, the mixture is determined to have reached a fully mature state, and compost products that have reached a fully mature state are obtained.

10. A method for composting, carbon sequestration, and emission reduction based on the staged addition of homologous biochar, as described in claim 9, is characterized in that... After determining that the mixture has reached a fully decomposed state, the process further includes: Product output and carbon sequestration application: The fully decomposed compost products are removed from the trough-type aerobic fermentation reaction system; the discharged compost products are directly applied to agricultural soil as soil amendment substrate.

Images