Method for mixing and composting sheep manure and corn straw

Abstract

The invention discloses a method for mixing and composting sheep manure and corn straws, which comprises the following steps: raw material preparation, filler addition, moisture adjustment, inoculant inoculation, composting fermentation, post-treatment and the like, in the filler addition process, biochar is modified to prepare a slow-release fertilizer, zeolite is added into different layers of a fermentation product for multiple times, and the fermentation product is uniformly mixed with the zeolite. In the preparation process of the hydrothermal carbonized biochar, attapulgite loaded with nutrient elements is added. According to the method, peculiar smell and ammonia gas emission in the initial stage of composting can be controlled by utilizing the adsorption characteristic of zeolite in different fermentation stages in the composting process, and the situation that the fermentation starting speed is affected due to insufficient available nutrients of microorganisms caused by adsorption of excessive zeolite is also avoided; meanwhile, attapulgite loaded with nutrient elements is added in the preparation process of the hydrothermal carbonized biochar, so that pores of the biochar can be filled, physical support is provided for pore walls of the biochar in the high-temperature and high-pressure hydrothermal reaction process, and the pores are prevented from collapsing under the action of pressure and temperature.

Description

Technical Field

[0001] This invention relates to the field of organic waste treatment and fertilizer preparation technology, specifically to a method for composting a mixture of sheep manure and corn stalks. Background Technology

[0002] Organic waste composting is an important technical means to achieve the recycling of agricultural resources, reduce environmental pollution, and produce high-quality organic fertilizer. With the development of agricultural production, the output of organic waste such as straw and livestock manure is increasing year by year. Converting these wastes into organic fertilizer through composting not only solves the pollution problem caused by open-air waste dumping but also replenishes soil organic matter, improves soil structure, and enhances soil fertility, meeting the needs of green agriculture development. Currently, composting technology is widely used to treat organic waste such as corn stalks and sheep manure. Its core principle is to utilize the metabolic action of microorganisms to decompose organic matter into stable humus. During this process, the fermentation environment needs to be optimized by adjusting parameters such as the carbon-nitrogen ratio, moisture, and aeration.

[0003] However, existing composting technologies still have many key problems that urgently need to be solved. First, the volatilization of odorous gases such as ammonia during composting leads to significant loss of core nutrients like nitrogen, reducing the fertilizer efficiency of the compost product, and also causes air pollution, impacting the surrounding environment. Second, the fermentation start-up efficiency is low, the heating rate is slow, and the high-temperature period is short, resulting in an excessively long maturation cycle (usually more than 30 days), and it is difficult to completely kill pathogens, insect eggs, and other harmful organisms. Third, biochar, as a commonly used composting additive, is prone to pore structure collapse during hydrothermal carbonization due to high temperature and pressure, losing its adsorption capacity and nutrient retention ability, thus limiting its role in optimizing the composting environment. Fourth, traditional methods of adding adsorbents such as zeolite (such as one-time addition or uniform mixing) have obvious defects; they either cannot effectively control initial odor and nutrient loss, or excessive adsorption leads to insufficient nutrients available to microorganisms, hindering the fermentation process. Fifth, the content of nutrients such as nitrogen, phosphorus, and potassium in compost products is low and the release is uneven, making it difficult to meet the needs of crop growth and limiting its application as a high-quality organic fertilizer.

[0004] These problems mean that existing composting technologies need improvement in terms of efficiency, product quality, and environmental friendliness. Therefore, developing a mixed composting method that can reduce ammonia volatilization, accelerate the fermentation process, protect the pore structure of biochar, and increase the nutrient content of compost has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0005] This invention provides a method for composting sheep manure and corn stalks to solve the problems of high ammonia volatilization, long heating time, long decomposition time, low nitrogen, phosphorus and potassium content in compost products, and easy collapse of hydrothermal carbonized biochar pores due to pressure and temperature in the existing technology.

[0006] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: This invention provides a method for composting sheep manure and corn stalks, including steps such as raw material pretreatment, adsorbent addition, biochar grading, composting fermentation, and post-treatment. Through precise design of raw material ratio, additive types and addition methods, and process parameters, the composting efficiency and product quality are synergistically improved.

[0007] In the raw material pretreatment stage, sheep manure with a moisture content of 40%-50% is selected as the main nitrogen source. Its moisture content can meet the initial metabolic needs of microorganisms and avoid anaerobic environment caused by excessive moisture. Corn stalks are selected as the carbon source and crushed to 5-10cm. This particle size can ensure the air permeability of the pile and promote the attachment and decomposition of microorganisms by increasing the specific surface area. The two are mixed at a mass ratio of 1:(0.2-0.5). This ratio can adjust the carbon-nitrogen ratio to a suitable range of 25-30:1, providing balanced nutrition for microorganisms and avoiding fermentation stagnation or excessive release of ammonia caused by carbon-nitrogen imbalance.

[0008] This invention produces highly effective organic fertilizer by adding sheep manure during the composting and fermentation process of corn stalks. Both of these main raw materials are common agricultural wastes. Using them for composting achieves waste reuse and reduces the environmental impact of waste. This composting method can transform inexpensive and widely available sheep manure and corn stalk waste into valuable fertilizer, significantly reducing fertilizer production costs.

[0009] The adsorbent is added using a combination of staged and layered zeolite addition. The total amount of zeolite is 3%-8% of the sheep manure mass. This range ensures its adsorption performance without overcrowding microbial activity space. In staged addition, 30%-40% is added in the initial stage (0-5 days) to control the high concentration of ammonia volatilization and odor caused by its strong adsorption properties. In the middle stage (6-15 days), 40%-50% is added, as microbial activity is vigorous and nutrient release is rapid; zeolite adsorbs excess nutrients to prevent loss. In the later stage (16 days to maturity), 10%-30% is added, primarily to stabilize the nutrient content and structure of the compost pile. In layered addition, 30%-40% is added to the bottom and top. The bottom zeolite adsorbs nutrients from the leachate, while the top intercepts volatile gases. The middle 20%-40% is added to balance the adsorption capacity of the compost pile. This three-dimensional distribution improves the adsorption efficiency of zeolite by more than 20% compared to traditional uniform addition.

[0010] Biochar is added using a tiered addition strategy, with the total addition amount accounting for 3%-8% of the sheep manure mass. Initially, pyrolysis char of straw with a particle size of 1-3 mm is added, accounting for 2%-6% of the sheep manure mass. Its large pore structure can significantly improve the permeability of the compost pile, promote the reproduction of aerobic microorganisms, and accelerate the temperature rise. Later, hydrothermal carbonization biochar with a particle size of 0.1-0.5 mm is added, accounting for 1%-2% of the sheep manure mass. The small particle size can fill the micropores of the compost pile, improve the compactness and stability of the compost, and enhance water retention and nutrient adsorption capacity.

[0011] Adding hydrothermal biochar in the later stages of composting can improve the stability and quality of the compost, fixing nutrients and harmful substances. Hydrothermal biochar typically possesses abundant functional groups and high adsorption capacity. In the later stages of composting, when most organic matter has been decomposed, adding hydrothermal biochar can further fix the remaining nutrients in the compost, such as phosphorus and potassium, preventing their loss during subsequent storage and use. Simultaneously, it can also adsorb harmful substances that may be generated during composting, such as heavy metal ions or recalcitrant organic pollutants, reducing the potential harm of compost products to soil and plants.

[0012] In some feasible ways, the preparation of hydrothermal carbonized biochar in this invention includes the following steps: First, attapulgite is pretreated by soaking it in a solution containing ammonium nitrate and potassium dihydrogen phosphate for 12-24 hours, loading nutrients through ion exchange, and then ultrasonically dispersed in 0.2-5 cm biomass (such as wheat straw or peanut shells) with stirring at 300-500 r / min for 15-30 min. The attapulgite accounts for 5%-10% of the biomass mass, and its nanoscale fiber structure can provide physical support for the pores of biochar during subsequent carbonization. Biomass undergoes a two-step carbonization process under nitrogen atmosphere protection: low-temperature carbonization at 300-450℃ for 2-4 hours (heating rate 8-12℃ / min) to remove volatile components and initially form pores; high-temperature carbonization at 600-800℃ for 4-5 hours to further stabilize the structure; finally, it is mixed with water at a ratio of 1:(2-5) and subjected to hydrothermal reaction at 150-220℃ for 60-120 minutes. Hydrothermal carbonization under high temperature and pressure can introduce more oxygen-containing functional groups, while attapulgite effectively prevents pore collapse, increasing the specific surface area of ​​biochar by 35% compared to the group without additives.

[0013] The hydrothermal carbonization biochar of this invention makes the compost structure more compact and stable. It fills the gaps between compost particles, creating a structure more conducive to storage and transportation. Furthermore, this compact structure reduces the risk of the compost being washed away by rain or blown away by wind after being mixed with soil, improving its usability. It also promotes further microbial activity and diversity by providing a unique living environment: the surface properties and internal structure of hydrothermal carbonization biochar differ from those of corn stalk biochar, providing a new habitat for microorganisms in the later stages of composting. Some microorganisms adapted to specific conditions in the later stages of composting can grow and reproduce on the surface and in the pores of hydrothermal carbonization biochar, further decomposing residual organic matter and increasing the degree of compost maturation. The unique chemical composition and physical structure of corn stalk biochar attract and support different types of microorganisms, thereby increasing the diversity of microorganisms in the compost. This diverse microbial community makes the compost more stable in the later stages and allows it to better interact with soil microorganisms after application, promoting the health of the soil ecosystem.

[0014] Corn stalk biochar can enhance plant growth and improve soil fertility. When compost products containing hydrothermally carbonized biochar are applied to the soil, they can improve soil fertility and physical properties. It can increase the soil's water and fertilizer retention capacity, enabling it to better retain moisture and nutrients, providing more favorable conditions for plant growth. For example, it can adsorb nutrients in the soil, preventing their loss, and slowly release these nutrients when needed by plants, improving fertilizer utilization efficiency. Hydrothermally carbonized biochar may contain substances that stimulate plant growth, such as plant hormone analogs or trace elements. These substances can promote root growth and development, enhance plant resistance, and thus improve plant yield and quality.

[0015] To further improve nutrient utilization, a slow-release carrier is introduced before adding zeolite. The preparation process is as follows: 25-30 parts by weight of straw biochar are impregnated with 50-60 parts by weight of urea solution, utilizing the biochar's pores to adsorb urea and form a support; then, an aqueous solution containing 5-10 parts by weight of sodium alginate and 5-10 parts by weight of aminosulfonic acid-modified carboxymethyl cellulose is added. The gelling properties of sodium alginate form a physical barrier, while the modified carboxymethyl cellulose enhances the binding force with urea through amino groups; finally, 2-8 parts by weight of ferric chloride (crosslinking agent) and 2-6 parts by weight of oxidized starch (to enhance stability) are added, forming a solidified carrier through ionic crosslinking and condensation reactions.

[0016] Slow-release carriers effectively encapsulate urea, allowing it to be released slowly during composting. In the initial stages of composting, the adsorption of biochar and the encapsulation by hydrogels prevent significant urea loss due to environmental factors such as rainwater runoff and rapid microbial decomposition. For example, in areas with heavy rainfall, urea in conventional fertilizers may seep into deeper soil layers, hindering effective absorption by plant roots. These slow-release carriers reduce urea leaching losses, ensuring a sustained supply of nutrients for the composting process and subsequent plant growth over a longer period.

[0017] Furthermore, this allows the fertilizer release rate to be better matched with the decomposition activities of microorganisms during composting and the nutrient requirements of plants during growth. In the early stages of composting, the decomposition of sheep manure and corn stalks by microorganisms is relatively slow. At this time, the slowly released urea can provide microorganisms with an appropriate nitrogen source, promoting their growth and the decomposition of organic matter. As composting progresses and plants grow, the fertilizer release rate can be appropriately adjusted according to environmental conditions (such as temperature, humidity, and microbial activity), avoiding situations of insufficient or excessive nutrient supply.

[0018] The presence of biochar and hydrogels can make the compost structure more stable. They bind the organic particles in the compost together, preventing it from becoming too loose or broken during turning or transportation. This stable structure helps maintain the uniformity of aeration channels and moisture distribution within the compost, improving the overall quality of the compost.

[0019] Besides the slow-release effect of urea, other components in the slow-release carrier also help reduce nutrient loss. For example, biochar can adsorb ammonium nitrogen produced during composting, preventing it from volatilizing into the air. Components such as oxidized starch may also interact with nutrients, further fixing them and making them less prone to loss. By reducing nutrient loss, more nutrients can be absorbed and utilized by plants, improving fertilizer utilization efficiency. The structure and composition of this slow-release carrier may also facilitate nutrient absorption by plant roots. The presence of hydrogels can improve the soil's aggregate structure, making the soil looser and conducive to root growth and extension. Simultaneously, some components in the slow-release carrier (such as biochar) may contain trace elements or active substances that promote root growth, further enhancing the plant's ability to absorb nutrients. By reducing nutrient leaching and volatilization losses, this nutrient slow-release carrier can reduce the risk of eutrophication and air pollution caused by fertilizer runoff. For example, in traditional fertilization, excessive urea entering water bodies can lead to the proliferation of algae, causing water quality deterioration. Using this slow-release carrier can effectively control the release of urea and reduce its negative impact on the environment.

[0020] In some feasible embodiments, the preparation of aminosulfonic acid-modified carboxymethyl cellulose in this invention includes the following steps: Sodium carboxymethyl cellulose was dissolved in an ethanol-water mixture with a volume fraction of 60%-80% to prepare a solution with a mass concentration of 8%-12%. This solution was then mixed with aminosulfonic acid at a ratio of 1:(0.8-1.2). At 85±5℃, 5%-10% of the mass of aminosulfonic acid was added dropwise as a carbodiimide condensing agent. After reacting for 1-3 hours, the pH was adjusted to 6.8-7.2. After purification, a product with a degree of substitution of 0.3-0.45 was obtained. Its amino group can form hydrogen bonds with urea, extending the nitrogen release cycle to more than 60 days.

[0021] During the composting fermentation stage, the moisture content should be adjusted to 50%-60%, which is the optimal range for microbial enzyme activity. Too low a moisture content will hinder metabolism, while too high a moisture content will lead to oxygen deficiency. Inoculated fungal agents (such as white-rot fungi and Trichoderma) are loaded onto zeolite at a ratio of 2-3:1. The porous structure of zeolite provides a shelter for the agents, increasing their survival rate by 40% compared to direct inoculation. Adding 50-100g of agent per kg of material can decompose complex organic matter in sheep manure and corn stalks, such as cellulose and lignin. The fermentation temperature should be controlled at 50-70℃, as thermophilic microorganisms are active within this temperature range, accelerating composting and killing pathogens. The compost should be turned every 2-3 days to balance temperature and oxygen levels. Composting is complete in 15-30 days. Finally, the residue is removed by sieving, yielding a nutrient-balanced and structurally stable compost product.

[0022] Turning the compost pile every 2-3 days ensures thorough mixing of the materials, guaranteeing even oxygen supply and preventing localized anaerobic environments. Turning also helps regulate temperature, making the composting process more stable and efficient. After 15-30 days of fermentation and post-processing, the resulting compost is of high quality. It is rich in organic matter, nitrogen, phosphorus, potassium, and other nutrients, effectively improving soil structure and increasing soil fertility. For example, the organic matter in the compost enhances the soil's water and fertilizer retention capacity, promotes soil aggregate formation, and benefits plant root growth. Screening removes incompletely decomposed residues and impurities, resulting in a purer final compost product that is easier to use and store, reducing potential adverse effects on soil and plants.

[0023] During composting, good aeration is beneficial for the growth and reproduction of aerobic microorganisms, enabling them to fully decompose organic matter. Biochar has a porous structure, and zeolite also has a large specific surface area and porosity. The addition of biochar and zeolite can improve the aeration and water retention of the compost. Biochar and zeolite also have a certain water retention capacity, and maintaining moisture in the fermenting material ensures a stable living environment for microorganisms during composting, preventing a decline in microbial activity due to excessive moisture loss.

[0024] On the one hand, biochar has various functional groups on its surface, which can adsorb nutrients produced during composting, such as ammonium nitrogen, preventing nutrient loss. Simultaneously, it can slowly release these nutrients in the later stages of composting, improving fertilizer utilization. Zeolite also has ion exchange capabilities, enabling it to adsorb and exchange cations in compost, regulating nutrient supply.

[0025] On the other hand, adjusting the moisture content of compost materials to 50%-60% is a suitable range for the composting process. At this moisture level, microbial metabolic activities can proceed smoothly, and enzyme activity can be guaranteed. If the moisture content is too high, it will lead to poor aeration inside the compost, creating an anaerobic environment, producing unpleasant odors, and affecting the quality of the compost. If the moisture content is too low, microbial growth will be inhibited, the decomposition rate of organic matter will slow down, and it will be detrimental to improving composting fermentation efficiency.

[0026] Compared with the prior art, the present invention has the following advantages: 1. This invention involves particle-grading biochar to allow for the addition of biochar of different particle sizes according to different stages and needs of composting. In the early stages of composting, adding larger-sized biochar increases the porosity of the compost, facilitating ventilation and heat dissipation. In the later stages of composting, adding smaller-sized biochar better fills the pores in the compost, improving its compactness and stability, and facilitating storage and transportation. Furthermore, biochar of different particle sizes can form different levels of pore structure with the composting materials, which is beneficial for the distribution and transport of moisture and nutrients, promoting the overall improvement of compost quality.

[0027] 2. This invention adds zeolite in layers, which allows the zeolite at the bottom to absorb the liquid and nutrients that seep out during composting, preventing nutrient loss and soil pollution; the zeolite at the top can absorb the odors and harmful gases produced during composting, reducing environmental pollution, and also helps maintain the humidity and temperature of the compost, promoting the decomposition of the compost.

[0028] 3. The addition of zeolite in this invention can provide a good adhesion environment for the microbial agent, increase the contact area between the microbial agent and the composting raw materials, improve the survival rate and activity of the microbial agent, and thus better exert the promoting effect of the microbial agent on composting. At the same time, the properties of zeolite itself can also work together with biochar to optimize the composting effect.

[0029] 4. This invention, by creating a slow-release nutrient carrier, allows the fertilizer release rate to better match the decomposition activities of microorganisms during composting and the nutrient requirements of plants during growth. In the early stages of composting, the decomposition of sheep manure and corn stalks by microorganisms is relatively slow. At this time, the slowly released urea can provide microorganisms with an appropriate nitrogen source, promoting their growth and the decomposition of organic matter. As composting progresses and plants grow, the fertilizer release rate can be appropriately adjusted according to environmental conditions (such as temperature, humidity, and microbial activity), avoiding situations of insufficient or excessive nutrient supply.

[0030] 5. This invention adds attapulgite loaded with nutrients during the hydrothermal carbonization process of biochar preparation, thereby filling the pores of the biochar. During the high-temperature and high-pressure hydrothermal reaction, it provides physical support for the pore walls of the biochar, preventing the pores from collapsing due to pressure and temperature. Moreover, due to the special structure of attapulgite and its adsorption characteristics for nutrients, the nutrients will not be lost rapidly, but will be gradually released into the surrounding environment over time, providing a long-term and stable supply of nutrients for plant growth, improving fertilizer utilization, and further enhancing the effect of fertilizer. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. 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.

[0032] Example 1: A method for composting sheep manure and corn stalks provided in this embodiment of the invention, the specific steps of which are as follows: Raw material pretreatment: Take 100 kg of sheep manure with a moisture content of 45% and mix it with 35 kg of corn stalks crushed to 7 cm (mass ratio 1:0.35). The corn stalks are the carbon source and the sheep manure is the nitrogen source. This ratio can be adjusted to a carbon-nitrogen ratio of 28:1, which is suitable for microbial growth.

[0033] Adsorbent addition: Add 5.5 kg of zeolite at 5.5% of the sheep manure weight, in three batches: 2.2 kg (40%) in the initial stage (day 1), 2.75 kg (50%) in the middle stage (day 8), and 0.55 kg (10%) in the later stage (day 20). When adding in layers, add 2.2 kg (40%) at the bottom, 1.1 kg (20%) in the middle, and 2.2 kg (40%) at the top. Natural clinoptilolite is selected as the zeolite to control ammonia by utilizing its adsorption properties.

[0034] Biochar addition in stages: 5.5 kg of biochar was added at 5.5% of the sheep manure mass. In the initial stage (day 1), 4.4 kg of pyrolysis biochar from corn stalks with a particle size of 2 mm (4.4% of the sheep manure mass) was added. In the later stage (day 15), 1.1 kg of hydrothermal carbonized biochar with a particle size of 0.3 mm (1.1%) was added. Preparation of hydrothermal carbonized biochar: 10 kg of wheat straw (biomass) was crushed to 2 cm and mixed with 0.75 kg of attapulgite clay (7.5% of the biomass mass) (pretreatment: soaking in a solution containing ammonium nitrate and potassium dihydrogen phosphate for 18 hours, stirring at 300 r / min + ultrasonic dispersion for 20 minutes). Under a nitrogen atmosphere, the temperature was increased to 375℃ at 10℃ / min for low-temperature carbonization for 3 hours, then increased to 700℃ for high-temperature carbonization for 4.5 hours. The mixture was then mixed with water at a 1:3 ratio and hydrothermally reacted at 180℃ for 90 minutes. The attapulgite clay supports the porous structure.

[0035] Sustained-release carrier addition: Before adding zeolite, a sustained-release carrier was prepared: 55 parts by mass of urea were dissolved in water, impregnated with 27 parts by mass of corn straw biochar, dried, and then coated with an aqueous solution containing 7 parts by mass of sodium alginate and 7 parts by mass of aminosulfonic acid-modified carboxymethyl cellulose. 5 parts by mass of ferric chloride and 4 parts by mass of oxidized starch were added for cross-linking and curing. Preparation of aminosulfonic acid-modified carboxymethyl cellulose: Sodium carboxymethyl cellulose was dissolved in a 70% ethanol-water solution (10% by mass concentration), mixed with aminosulfonic acid at a 1:1 mass ratio, and 7% by mass of carbodiimide condensing agent (based on aminosulfonic acid) was added dropwise at 85℃. The reaction was allowed to proceed for 2 hours, the pH was adjusted to 7.0, and the product with a degree of substitution of 0.38 was obtained after purification.

[0036] Composting fermentation: Adjust the moisture content to 55%, inoculate with white rot fungicide at a rate of 75g per kg of material (loaded by zeolite, with a zeolite to fungicide mass ratio of 2.5:1), ferment at 55℃ for 22 days, turning the pile every 2 days.

[0037] Post-processing: Screening removes residue, yielding well-rotted compost.

[0038] Table 1 is a comparison table of fertilizer performance parameters obtained in Examples 1-3 and Comparative Examples 1-7.

[0039] Analysis of Table 1 shows that Examples 1-3 exhibited excellent performance across all parameters. The key advantages are: First, the phased and layered addition of zeolite precisely matched the ammonia adsorption requirements at different stages of composting, controlling ammonia volatilization at 2.5-2.7 kg, a 15%-34% reduction compared to the control group, and significantly improving nitrogen retention. Second, the graded addition of biochar (large-particle-size biochar initially improving permeability, and small-particle-size hydrothermally carbonized biochar enhancing fertilizer retention in the later stages) combined with attapulgite soil pore support resulted in a biochar porosity of 56%-60%, shortening the time to reach 50℃ to 2.8-3.2 days, increasing the maximum temperature to 63-67℃, shortening the maturation time to 20-25 days, and effectively killing pathogens during the high-temperature period. Third, the slow-release carrier constructed from aminosulfonic acid-modified carboxymethyl cellulose extended the nutrient slow-release period to 60-70%. In addition, the nutrient adsorption capacity of hydrothermal carbonized biochar is combined to achieve nitrogen, phosphorus and potassium contents of 2.7%-2.9%, 1.1%-1.3% and 1.4%-1.6% respectively, which is 15%-40% higher than the control ratio.

[0040] Comparative Examples 1-7 suffered from performance degradation due to the absence of the core elements of this invention: Comparative Example 1 (conventional method) had the highest ammonia volatilization (3.8 kg) and the longest composting time (30 days) due to the lack of stratified and staged zeolite addition, ungraded biochar, and slow-release carrier, demonstrating the defects of traditional methods such as severe nutrient loss and low efficiency; Comparative Example 2 (one-time zeolite addition) resulted in suppressed microbial activity due to excessive adsorption in the initial stage, extending the heating time to 3.8 days, and ammonia volatilization was 27% higher than the example; Comparative Example 3 (ungraded biochar) had poor fertilizer retention due to the lack of small-particle biochar filling the pores in the later stage, with a nitrogen content of only 2.3%; Comparative Example 4 (non-hydrothermal carbonization biochar) lacked the functional groups introduced by the hydrothermal reaction, resulting in insufficient nutrient adsorption capacity and a shortened slow-release period to 42 days. The nitrogen content in Comparative Examples 5 (without a slow-release carrier) and 6 (ordinary carboxymethyl cellulose) was 10%-15% lower than in the previous examples due to the inability to effectively control nutrient release. Comparative Example 7 (without attapulgite) experienced a decrease in maximum temperature to 60°C and a prolonged composting time due to biochar pore collapse (porosity 46%). These disadvantages demonstrate the irreplaceable nature of technologies such as staged stratified zeolite addition, biochar grading and hydrothermal carbonization, and slow-release carrier modification.

[0041] The testing methods and standards for the relevant performance parameters in Table 1 above are as follows: Ammonia volatilization: The content of volatilized ammonia was determined by boric acid absorption method using the closed-space gas collection method, referring to "GB / T 36195-2018 Determination of Ammonia Volatilization in Livestock and Poultry Manure Composting".

[0042] Time to reach 50℃: The temperature at the center of the reactor was monitored in real time using multi-point temperature sensors (accuracy ±0.5℃), and the time to reach 50℃ was recorded.

[0043] Composting time: Refer to the "NY / T 3442-2019 Technical Specification for Evaluation of Compost Maturity", and determine the maturity endpoint by combining the temperature stabilization period (temperature fluctuation ≤2℃ for 5 consecutive days), germination index (≥80%) and C / N ratio (≤20).

[0044] Nitrogen, phosphorus, and potassium content: Nitrogen content was determined by the Kjeldahl method (GB / T 8572-2010), phosphorus content was determined by the molybdenum-antimony colorimetric method (GB / T 8573-2010), and potassium content was determined by the flame photometry method (GB / T 8574-2010).

[0045] Porosity of biochar: The ratio of total pore volume to particle volume of biochar was determined by mercury porosimetry (GB / T 21650.3-2011).

[0046] Nutrient slow-release period: Referring to GB / T 23348-2009 Slow-release fertilizers, the time when the cumulative nutrient release rate reaches 80% is determined by water immersion extraction-dynamic leaching method.

[0047] Example 2: A method for composting sheep manure and corn stalks provided in this embodiment of the invention, the specific steps of which are as follows: Raw material pretreatment: Take 100 kg of sheep manure with a moisture content of 40% and mix it with 20 kg of corn stalks crushed to 5 cm (mass ratio 1:0.2), and control the carbon-nitrogen ratio to 30:1.

[0048] Adsorbent addition: Add 3 kg of zeolite at 3% of the sheep manure weight, in three batches: 0.9 kg (30%) in the initial stage (day 1), 1.2 kg (40%) in the middle stage (day 7), and 0.9 kg (30%) in the later stage (day 18); stratified addition: 1.2 kg (40%) at the bottom, 0.6 kg (20%) in the middle, and 1.2 kg (40%) at the top, using mordenite.

[0049] Biochar addition in stages: Add 3 kg of biochar at 3% of sheep manure mass. Initially, add 2 kg of pyrolysis biochar from corn stalks with a particle size of 1 mm (accounting for 2%), and later add 1 kg of hydrothermal carbonized biochar with a particle size of 0.1 mm (accounting for 1%). Preparation of hydrothermal carbonized biochar: Take 5 kg of rice straw (crushed to 0.2 cm), add 0.25 kg of attapulgite clay (5% of biomass mass) (soak for 12 h, stir at 500 r / min + sonicate for 15 min); heat to 300℃ at 8℃ / min for low-temperature carbonization for 2 h, then heat to 600℃ for high-temperature carbonization for 4 h, mix with water at a ratio of 1:2, and hydrothermally react at 150℃ for 60 min.

[0050] Slow-release carrier addition: 50 parts by weight of urea impregnate 25 parts by weight of corn straw biochar, which is then coated with an aqueous solution containing 5 parts by weight of sodium alginate and 5 parts by weight of aminosulfonic acid modified carboxymethyl cellulose (degree of substitution 0.3), and then solidified with 2 parts by weight of ferric chloride and 2 parts by weight of oxidized starch.

[0051] Composting fermentation: Adjust the moisture content to 50%, add 50g of Trichoderma agent per kg of material (zeolite to agent ratio 2:1), ferment at 50℃ for 15 days, and turn the pile every 3 days.

[0052] Post-processing: Screening yields compost products.

[0053] Example 3: A method for composting sheep manure and corn stalks provided in this embodiment of the invention, the specific steps of which are as follows: Raw material pretreatment: Take 100kg of sheep manure with a moisture content of 50% and mix it with 50kg of corn stalks crushed to 10cm (mass ratio 1:0.5), with a carbon-nitrogen ratio of 25:1.

[0054] Adsorbent addition: Add 8 kg of zeolite at 8% of the sheep manure weight, in three batches: 3.2 kg (40%) in the initial stage (day 2), 4 kg (50%) in the middle stage (day 10), and 0.8 kg (10%) in the later stage (day 25); stratified addition: 3.2 kg (40%) at the bottom, 1.6 kg (20%) in the middle, and 3.2 kg (40%) at the top, using clinoptilolite.

[0055] Biochar addition in stages: Add 8 kg of biochar at 8% of the sheep manure mass. Initially, add 6 kg of pyrolysis biochar from corn stalks with a particle size of 3 mm (6%), and later add 2 kg of hydrothermal carbonized biochar with a particle size of 0.5 mm (2%). Preparation of hydrothermal carbonized biochar: Take 10 kg of peanut shells (crushed to 5 cm), add 1 kg of attapulgite clay (10% of the biomass mass) (soak for 24 h, stir at 400 r / min + sonicate for 30 min); heat to 450℃ at 12℃ / min for low-temperature carbonization for 4 h, then heat to 800℃ for high-temperature carbonization for 5 h, mix with water at a ratio of 1:5, and hydrothermally react at 220℃ for 120 min.

[0056] Slow-release carrier addition: 60 parts by weight of urea impregnate 30 parts by weight of corn straw biochar, which is then coated with an aqueous solution containing 10 parts by weight of sodium alginate and 10 parts by weight of aminosulfonic acid-modified carboxymethyl cellulose (degree of substitution 0.45), and then solidified with 8 parts by weight of ferric chloride and 6 parts by weight of oxidized starch.

[0057] Composting fermentation: Adjust the moisture content to 60%, add 100g of Trichoderma harzianum agent per kg of material (zeolite to agent ratio 3:1), ferment at 70℃ for 30 days, turning the pile every 2 days.

[0058] Post-processing: Screening yields compost products.

[0059] Comparative Example 1: The difference between this comparative example and Example 1 is that it uses a conventional composting method, without the staged / layered addition of zeolite (5.5 kg of zeolite is added uniformly at once), without grading the biochar (5.5 kg of pyrolysis char from corn stalks with a particle size of 2 mm is added directly), without adding a slow-release carrier, and with direct inoculation of the microbial agent (without zeolite loading). The hydrothermal carbonization of the biochar does not use attapulgite clay. The remaining steps (raw material ratios, fermentation parameters, etc.) are the same as in Example 1.

[0060] Comparative Example 2: The difference between this comparative example and Example 1 is that 5.5 kg of zeolite was added all at once at the beginning of composting (day 1), instead of being added in three stages. The stratification method was the same as in Example 1. The remaining steps (biochar grading, slow-release carrier, microbial agent, etc.) were the same as in Example 1.

[0061] Comparative Example 3: The difference between this comparative example and Example 1 is that the 5.5 kg of biochar was all corn stalk pyrolysis char with a particle size of 2 mm, and it was not added in stages (added all at once in the initial stage), and hydrothermal carbonization of biochar was not used. The remaining steps (zeolite addition, slow-release carrier, etc.) were the same as in Example 1.

[0062] Comparative Example 4: The difference between this comparative example and Example 1 is that the 1.1 kg of biochar added later was pyrolysis biochar of corn stalks with a particle size of 0.3 mm, rather than hydrothermal carbonized biochar, and did not undergo hydrothermal carbonization treatment. The remaining steps are the same as in Example 1.

[0063] Comparative Example 5: The difference between this comparative example and Example 1 is that the sustained-release carrier is not prepared and added, while the remaining steps (zeolite addition, biochar fractionation, etc.) are the same as in Example 1.

[0064] Comparative Example 6: The difference between this comparative example and Example 1 is that ordinary carboxymethyl cellulose is used instead of aminosulfonic acid modified carboxymethyl cellulose in the sustained-release carrier, while the remaining preparation steps (urea loading, cross-linking and curing, etc.) are the same as in Example 1.

[0065] Comparative Example 7: The difference between this comparative example and Example 1 is that no attapulgite is added during the preparation of hydrothermal carbonization biochar. The remaining preparation steps (carbonization temperature, hydrothermal reaction, etc.) are the same as in Example 1, and the remaining composting steps are the same as in Example 1.

[0066] Any numerical values ​​cited herein include all values ​​ranging from a lower limit to an upper limit, increasing by one unit, with at least two units between any lower and any higher value. For example, if the quantity of a component or the value of a process variable (e.g., temperature, pressure, time, etc.) is described as being from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in this specification. For values ​​less than 1, a unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1, etc. These are merely examples intended for explicit expression, and it can be assumed that all possible combinations of values ​​listed between the minimum and maximum values ​​are similarly explicitly stated in this specification.

[0067] Unless otherwise stated, all ranges include the endpoints and all numbers between them. The terms "approximately" or "about" used with ranges apply to both endpoints of the range. Thus, "approximately 20 to 30" is intended to cover "approximately 20 to approximately 30," including at least the specified endpoints.

[0068] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the appended claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the inventors have not considered that subject matter as part of the disclosed inventive subject matter.

[0069] The present invention has been described by way of example above. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A method for mixed composting with sheep manure and corn stalks, characterized by, The method comprises the following steps: (1) raw material pretreatment: mixing sheep manure with a water content of 40%-50% and corn straw crushed to 5-10 cm at a mass ratio of 1:(0.2-0.5); (2) adsorbent addition: adding zeolite three times at the initial, middle and late stages of composting, with the total amount accounting for 3%-8% of the mass of sheep manure; (3) biochar graded addition: adding first-particle-size biochar at the initial stage and second-particle-size biochar at the late stage, with the total amount accounting for 3%-8% of the mass of sheep manure, and the second-particle-size biochar added at the late stage being hydrothermal carbonized biochar, and adding 5%-10% of attapulgite by mass of biomass as a pore support during the preparation of the hydrothermal carbonized biochar; (4) compost fermentation: adjusting the water content of the material to 50%-60%, inoculating 50-100 g of microbial inoculum per kg of material, and composting at 50-70 ℃ for 15-30 days, with turning every 2-3 days; (5) post-treatment: removing unrotted residues by screening to obtain mature compost.

2. The method of claim 1, wherein, In the step (2), the zeolite is added at a ratio of 30%-40% at the initial stage, 40%-50% at the middle stage, and 10%-30% at the late stage; And / or, the zeolite is added in layers, with the total amount of 30%-40% at the bottom, 20%-40% in the middle, and 30%-40% at the top.

3. The method of claim 1, wherein, In the step (3): The first-particle-size biochar is straw pyrolysis carbon with a particle size of 1-3 mm, and the amount added accounts for 2%-6% of the mass of sheep manure; The second-particle-size biochar has a particle size of 0.1-0.5 mm, and the amount added accounts for 1%-2% of the mass of sheep manure.

4. The method of claim 1, wherein, The attapulgite in the step (3) is pretreated, which comprises the following steps: Soaking in a solution containing ammonium nitrate and potassium dihydrogen phosphate nutrient elements for 12-24 h for nutrient element loading; Dispersing in biomass with a particle size of 0.2-5 cm by stirring at 300-500 r / min for 15-30 min.

5. The method of claim 5, wherein, The preparation of the hydrothermal carbonized biochar comprises the following steps: a) heating the biomass with dispersed attapulgite to 300-450 ℃ at a heating rate of 8-12 ℃ / min under a nitrogen atmosphere, low-temperature carbonization for 2-4 h; b) continuing to heat at a heating rate of 8-12 ℃ / min to 600-800 ℃, high-temperature carbonization for 4-5 h; c) mixing the high-temperature carbonization product with water at a mass ratio of 1:(2-5), and hydrothermal reaction at 150-220 ℃ for 60-120 min.

6. The method of claim 1, wherein, Before adding the zeolite in step (2), a slow-release carrier is prepared and mixed into the material, and the slow-release carrier is obtained by the following steps: i. urea loading: preparing 50-60 parts by mass of urea into a solution, impregnating 25-30 parts by mass of straw biochar, filling urea into the pores of the biochar, and drying to obtain the carrier; ii. gel coating: coating the carrier with an aqueous solution containing 5-10 parts by mass of sodium alginate and 5-10 parts by mass of modified carboxymethyl cellulose with sulfamic acid; iii. cross-linking and solidification: adding 2-8 parts by mass of ferric chloride and 2-6 parts by mass of oxidized starch to form a solidified slow-release carrier through ionic cross-linking and condensation reaction.

7. The method of claim 7, wherein the slow release carrier is prepared by, The sulfamate-modified carboxymethyl cellulose is prepared by the following steps: (1) dissolving sodium carboxymethyl cellulose in an ethanol-water mixed solvent with an ethanol volume fraction of 60-80%, to prepare a solution with a mass concentration of 8-12%; (2) adding sulfamic acid, and controlling the mass ratio of sodium carboxymethyl cellulose to sulfamic acid to be 1:(0.8-1.2); (3) under constant temperature stirring at 85±5℃, adding a carbodiimide condensing agent accounting for 5-10% of the mass of the sulfamic acid, and reacting for 1-3 hours; (4) after the reaction is completed, adjusting the pH to 6.8-7.2 with a sodium hydroxide solution; (5) after ethanol precipitation, pure water washing, and vacuum drying, sulfamate-modified carboxymethyl cellulose with a degree of substitution of 0.3-0.45 is obtained.

8. The method according to any one of claims 1 to 8, characterized in that, In the step (4), the microbial agent is a fungal agent, and is loaded on a zeolite carrier, with a mass ratio of the zeolite to the agent being (2-3):

1.

9. The method of claim 1, wherein, The biomass in the hydrothermal carbonization biochar includes at least one of wheat straw, rice straw, and peanut hulls.

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