A soil conditioner and its preparation method

Abstract

This application relates to the field of soil conditioner preparation technology, and in particular to a soil conditioner and its preparation method. The soil conditioner comprises porous biochar-based microspheres, which are made from food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and a binder. The food sludge-based biochar is produced by the pyrolysis of food sludge; the cellulose-based biochar is produced by the pyrolysis of waste biomass materials rich in cellulose; the binder is a disintegrating organic binder combined with at least one of illite powder, bentonite powder, dolomite powder, diatomaceous earth powder, kaolin powder, montmorillonite powder, and attapulgite powder; the disintegrating organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid. This soil conditioner can adsorb and remove heavy metal elements, adjust soil pH, improve soil structure and physicochemical properties, enhance water, soil, and fertilizer retention capacity, and effectively promote crop growth and development, thereby increasing crop yield and income.

Description

Technical Field

[0001] This application relates to the field of soil conditioner preparation technology, and in particular to a soil conditioner and its preparation method. Background Technology

[0002] Food sludge, a byproduct of food wastewater treatment produced by food companies, contains a variety of components, including organic matter, inorganic matter, and microorganisms. It also contains harmful organic matter, heavy metals, and harmful pathogens. If not properly treated, it may cause serious environmental damage and secondary pollution, placing a heavy burden on the environment and the economy.

[0003] The existing sludge treatment methods mainly include the following five types:

[0004] 1. Compression treatment method: The sludge is compressed under high pressure into a hard solid, and then buried underground. This not only occupies land resources, but also causes soil and groundwater pollution problems in the landfill area.

[0005] 2. Composting method: Sludge and organic waste are composted together. After a period of fermentation, the organic matter in the sludge is decomposed into fertilizer by microorganisms. However, the composting method has a long treatment cycle, low efficiency in removing heavy metals, and is prone to causing secondary pollutants.

[0006] 3. Incineration: High-temperature incineration of sludge can completely eliminate organic matter and pathogens in the sludge. However, incineration consumes energy and produces harmful gases such as carbon dioxide.

[0007] 4. Melting method: The sludge is heated to a high temperature and melted into a glassy state, which helps to fix the pollutants. However, this method requires high technical support and expensive equipment, and cannot achieve industrial-scale mass treatment of sludge.

[0008] 5. Landfilling: As an early and common method of sludge treatment, its harmful effects have gradually become apparent. Although the sludge is transported to a special landfill, buried underground, and covered with an impermeable layer and corrosion-resistant covering, the landfilled sludge will still pollute the soil and groundwater in the landfill area. There are frequent reports of soil and groundwater pollution problems caused by this method of sludge treatment, and the landfilling method has been gradually phased out.

[0009] To address the environmental and economic harms caused by food waste sludge, an environmentally friendly method for its treatment is urgently needed. To this end, the inventors have provided a soil conditioner prepared from food waste sludge and its preparation method, transforming food waste sludge into a valuable resource for soil conditioner production, thus meeting the requirements of sustainable green development. Summary of the Invention

[0010] To address the environmental and economic harm caused by food waste sludge, this invention provides a soil conditioner and its preparation method, turning food waste sludge into a valuable resource. By subjecting food waste sludge to high-temperature pyrolysis, a food waste sludge-based carbon material is obtained for use in the production of the soil conditioner.

[0011] The soil conditioner provided by this invention is achieved through the following technical solution:

[0012] A soil conditioner includes porous biochar-based microspheres, which are made from food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agents, and binders. The food sludge-based biochar is produced by the pyrolysis of food sludge. The cellulose-based biochar is produced by the pyrolysis of cellulose-rich waste biomass materials. The cellulose-rich waste biomass materials include rice straw, wheat straw, corn straw, sorghum straw, reed straw, waste sawdust, shredded dead branches, shredded dead bark, shredded leaves, shredded dead grass, shredded coconut shells, bagasse, and coffee grounds. The single-atom modified zeolite agent comprises a porous zeolite agent carrier and a single-atom metal loaded on the surface and pore walls of the porous zeolite agent carrier, wherein the single-atom metal comprises at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the single-atom metal loading rate in the single-atom modified zeolite agent is 1-5 wt%; the binder is a disintegrating organic binder combined with at least one of illite powder, bentonite powder, dolomite powder, diatomite powder, kaolin powder, montmorillonite powder, and attapulgite powder; the disintegrating organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid.

[0013] This invention effectively removes harmful pathogens, organic pollutants, and heavy metal particles from food sludge through a specific pyrolysis process. The resulting food sludge-based biochar has the advantages of high porosity, high surface area, and low heavy metal content, turning food sludge into a valuable resource for the production of soil conditioners.

[0014] The necessity of adding cellulose-based biochar materials: Food sludge-based biochar, as a peat material, has a relatively lower content of inorganic carbon and beneficial trace mineral particles compared to cellulose-based biochar. To meet the soil fertility restoration requirements during soil remediation, a blend of food sludge-based and cellulose-based biochar materials can better satisfy soil remediation needs. Cellulose-based biochar materials have a wide range of synthetic sources and low preparation costs; blending the two also helps reduce the overall production cost of soil conditioners. Among existing soil remediation products, the production cost of soil conditioners is a major factor restricting their widespread application.

[0015] Food sludge-based biochar and cellulose-based biochar materials in porous biochar-based microspheres can significantly reduce the available form of heavy metals in soil and decrease their migration in the environmental medium through interactive mechanisms such as physical adsorption, ion adsorption, ion exchange, and precipitation complexation, thereby reducing the biotoxicity of heavy metals in soil. Furthermore, the food sludge-based biochar and cellulose-based biochar materials in porous biochar-based microspheres also exhibit improved performance regarding Al... 3+ It has strong adsorption and fixation capabilities, regulates the composition of soil exchangeable acids, and reduces soil exchangeable Al. 3+ Adjusting the ratio of exchangeable acids in the soil can effectively alleviate the problem of aluminum toxicity in the soil, thereby promoting crop growth and development.

[0016] The porous biochar-based microspheres contain food sludge-based biochar and cellulose-based biochar materials. Their high porosity and large surface area structure can effectively absorb, retain, and retain water and fertilizer, increase soil porosity, reduce soil nutrient loss, and improve soil physical properties.

[0017] In summary, the soil conditioner provided by this invention can adsorb and remove heavy metal elements and trivalent aluminum ions, reducing heavy metal hazards and aluminum toxicity; it can react with H... + The association reaction increases soil volume, thereby adjusting soil pH, increasing soil porosity, reducing soil nutrient loss, improving soil physical properties, and enhancing water, soil and fertilizer retention capacity. This, in turn, promotes crop growth and development, leading to increased crop yield and income.

[0018] Preferably, the single-atom modified zeolite agent accounts for 0.5-2.0 wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8-20 wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 78-90 wt% of the total mass of the porous biochar-based microspheres; and the mass ratio of the food sludge-based biochar to the cellulose-based biochar is (1-4):(1-4).

[0019] By adopting the above technical solutions, the overall production cost of soil conditioners can be reduced.

[0020] Preferably, the preparation method of the food sludge-based biochar is as follows:

[0021] Step 1: Take 10 parts of food sludge and mix it evenly with 90-190 parts of water to obtain a sludge suspension;

[0022] Step 2: While stirring at 100-300 rpm, add an organic complex to the sludge suspension. The organic complex accounts for 0.01-0.10 wt% of the mass of the food sludge. Divide the organic complex into at least three portions, with an interval of 15-30 min between each portion. After the organic complex is added, continue stirring at 100-300 rpm for 30-60 min.

[0023] Step 3: Add a pH adjuster to the sludge suspension to adjust the pH of the sludge suspension to 6.8-7.1. Add magnetic single-atom modified halloysite, which accounts for 0.05-0.50 wt% of the mass of the food sludge. Divide the magnetic single-atom modified halloysite into at least three portions, with an interval of 15-30 minutes between two portions. After the magnetic single-atom modified halloysite is added, continue stirring at 100-300 rpm for 30-60 minutes.

[0024] Step 4: Let the sludge stand under ultraviolet light for 12-24 hours, then extract the upper layer of water to the sewage pipe network. The food sludge treated with organic complex + magnetic single-atom modified halloysite is then subjected to dry-wet separation to obtain food sludge granules with a water content of 25-40 wt%.

[0025] Step 5: Dry the food sludge granules from Step 4 at 120-160℃ to reduce the moisture content to ≤3.0%. Then grind and crush the dried food sludge granules to obtain crushed food sludge material. Perform magnetic separation on the crushed food sludge material. After magnetic separation, separate the recovered magnetic single-atom modified halloysite and the crushed food sludge material to be pyrolyzed.

[0026] Step six involves pyrolyzing the crushed food sludge from step five to obtain food sludge-based biochar with high specific surface area and high porosity.

[0027] This invention employs the latest single-atom catalyst technology to degrade organic matter and eliminate harmful pathogens in food sludge. Combined with a specific pyrolysis process, it effectively removes harmful pathogens, organic pollutants, and heavy metal particles from food sludge. The resulting food sludge-based biochar has the advantages of high porosity, high surface area, and low heavy metal content, turning food sludge into a valuable resource and solving the secondary pollution problem of traditional pyrolysis processes.

[0028] Preferably, the magnetic single-atom modified halloysite comprises single-atom modified halloysite and nanomagnetic particles grafted onto the surface of the single-atom modified halloysite, wherein the loading rate of the nanomagnetic particles in the magnetic single-atom modified halloysite is 0.5-5 wt%; the single-atom modified halloysite comprises halloysite with an average particle size of 0.5-20 micrometers and single-atom metals loaded on the surface of the halloysite and the pore wall surface, wherein the single-atom metals include at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the loading rate of the single-atom metals in the single-atom modified halloysite is 1-5 wt%.

[0029] Preferably, the nanomagnetic particles are nano-iron oxide (Fe3O4) with a particle size distribution of 5-30 nm.

[0030] The magnetic single-atom modified halloysite in this invention can degrade organic matter in food sludge and disinfect harmful pathogens. It can also be recycled and reused through magnetic separation technology, which greatly reduces the cost of harmless treatment of food sludge, helps to reduce the total production cost of soil conditioner, and thus enhances the competitiveness of this product.

[0031] Preferably, the method for preparing the magnetic single-atom modified halloysite is as follows:

[0032] Step 1: Preparation of single-atom modified halloysite;

[0033] Step 2: Mix 10 parts of single-atom modified halloysite and 40-90 parts of 0.5-2wt% epoxy silane aqueous solution evenly and then perform ultrasonic dispersion treatment for 0.5-1h. After ultrasonic dispersion treatment, filter under reduced pressure and vacuum dry the resulting solid to obtain epoxy silane grafted modified single-atom modified halloysite.

[0034] Step 3: Mix 10 parts of nanomagnetic particles and 40-90 parts of aminosilane aqueous solution with a concentration of 0.5-2wt% evenly, and then perform ultrasonic dispersion treatment for 0.5-1h. After ultrasonic dispersion treatment, filter under reduced pressure, and then vacuum dry the resulting solid to obtain aminosilane grafted modified nanomagnetic particles.

[0035] Step 4: Disperse 10 parts of epoxy silane-grafted modified single-atom halloysite and 0.053-0.53 parts of amino silane-grafted modified nanomagnetic particles in 90-190 parts of polar aprotic organic solvent, mix evenly, heat to 45-60℃, and maintain at 45-60℃ for 1-4 hours for ultrasonic dispersion treatment. The ultrasonic dispersion frequency is 30-44kHz and the ultrasonic dispersion power is 200-600W. After ultrasonic dispersion treatment, perform vacuum filtration, vacuum drying of the obtained filter material, and ball milling of the obtained solid material to obtain magnetic single-atom modified halloysite. The nanomagnetic particles are grafted onto the surface of single-atom modified halloysite through amide bonds.

[0036] The preparation process of magnetic single-atom modified halloysite provided by this invention is relatively simple. Nanomagnetic particles can be firmly grafted onto the surface of single-atom modified halloysite through amide bonds, thereby ensuring the efficiency of magnetic separation and recovery of magnetic single-atom modified halloysite, and thus reducing the cost of using food sludge biochar materials.

[0037] Preferably, in step six, 100 parts of the crushed food sludge from step five are weighed and mixed evenly with 0.5-2 parts of thiourea and placed in a muffle furnace for pyrolysis. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 5-10°C / min and held for 5-10 min, then heated to 360-420°C at a heating rate of 10-20°C / min and held for 40-50 min, then heated to 560-650°C at a heating rate of 5-10°C / min and held for 10-15 min, and finally heated to 160-240°C at a cooling rate of 5-10°C / min and allowed to cool naturally to room temperature. The resulting solid is then ball-milled to obtain food sludge-based biochar.

[0038] Preferably, in step six, 100 parts of the crushed food sludge from step five are weighed and mixed evenly with 1.2-1.6 parts of thiourea and then placed in a muffle furnace for pyrolysis. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 10°C / min and held for 10 min, then heated to 400-420°C at a heating rate of 20°C / min and held for 45 min, then heated to 580-600°C at a heating rate of 10°C / min and held for 15 min, and finally heated to 180-200°C at a cooling rate of 10°C / min and allowed to cool naturally to room temperature. The resulting solid is then ball-milled to obtain food sludge-based biochar.

[0039] The crushed food sludge to be pyrolyzed is mixed with ammonia-thiourea. The ammonia-thiourea is fractionated into ammonia and hydrogen sulfide gas at 225-230℃. At high temperatures (360-650℃), the ammonia and hydrogen sulfide gas can perform nitrogen and sulfur functional modification on the outer surface and pore wall surface of the food sludge biochar. Nitrogen and sulfur functional sites, amino groups, sulfur-containing functional groups, and carboxyl functional groups are grafted onto the surface of the food sludge biochar and the inner wall surface of its pores, which further improves the water retention and fertilizer retention performance, while also increasing soil fertility and enhancing the ability to adsorb, passivate, and eliminate heavy metal ions.

[0040] Preferably, the porous biochar-based microspheres further include calcined shell powder and porous coal gangue powder, wherein the calcined shell powder accounts for 5-10 wt% of the total mass of the porous biochar-based microspheres, and the porous coal gangue powder accounts for 5-10 wt% of the total mass of the porous biochar-based microspheres; the single-atom modified zeolite agent accounts for 0.5-2.0 wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8-20 wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 58-80 wt% of the total mass of the porous biochar-based microspheres; and the mass ratio of the food sludge-based biochar to the cellulose-based biochar is (1-4):(1-4).

[0041] To optimize the production cost of soil conditioners, low-cost calcined shell powder and porous coal gangue powder are incorporated into them. The production cost of calcined shell powder and porous coal gangue powder is lower than that of food sludge biochar. Appropriate incorporation of calcined shell powder and porous coal gangue powder can reduce the production cost of soil conditioners and also give them new advantages in soil remediation.

[0042] Calcined shell powder can reduce the aluminum content in cation exchange complexes, regulate soil pH, and alleviate soil acidification. The calcium ions it contains react with Na+ on the surface of soil colloids. + Mg 2+ The exchange process can transform the soil from a hydrophilic colloid to a hydrophobic colloid, improving soil structure and permeability, thereby achieving desalination and inhibiting salt return.

[0043] Porous coal gangue powder is rich in organic matter, providing nutrients and water to promote plant growth. Its abundant minerals provide trace elements and mineral nutrients to the soil, meeting the needs of plant growth. Using waste porous coal gangue powder as an adjunct to a soil conditioner solves the problem of its hazardous waste disposal. Furthermore, as a soil conditioner, it can increase soil fertility, improve soil structure, enhance water retention and aeration, and ultimately improve soil fertility and plant growth capacity.

[0044] Porous coal gangue powder is made from 95 parts coal gangue powder, 5 parts cement, 0.05 parts aluminum powder, and water (water-cement ratio of 0.60-0.65). If the accurately measured coal gangue powder, cement, aluminum powder, and water are mixed, foamed, and molded, then cured in a curing box at 70℃ for 12 hours, and after demolding, dried in a drying oven at 105℃ for 24 hours, it can be crushed to obtain the product.

[0045] Preferably, the soil conditioner is made of porous biochar-based microspheres, biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules; the amount of porous biochar-based microspheres added to the soil conditioner is 75-90 wt%; the amount of biodegradable compound fertilizer capsules added to the soil conditioner is 4-10 wt%; the amount of biodegradable organic complex capsules added to the soil conditioner is 2-10 wt%; and the amount of biodegradable organic fertilizer capsules added to the soil conditioner is 4-10 wt%.

[0046] The function of biodegradable compound fertilizer capsules: Under water erosion, the outer biodegradable film of the biodegradable compound fertilizer capsule breaks and slowly releases the compound fertilizer gel, which can effectively improve soil fertility and promote the growth and development of crops.

[0047] The function of biodegradable organic complex capsules: Under water erosion, the outer biodegradable film of the biodegradable organic complex capsule breaks and slowly releases the organic complex. On the one hand, it can effectively complex and remove heavy metal particles and reduce the toxicity of heavy metal ions. On the other hand, by selecting organic complexes of different acid and alkali types, it can also adjust the soil pH value, improve the soil structure and physical properties, and create a soil environment suitable for the growth and development of crops, which has a positive significance for increasing crop yield and income.

[0048] The function of biodegradable organic fertilizer capsules: When the outer biodegradable film of the biodegradable organic fertilizer capsule breaks, it slowly releases organic fertilizer, which can improve soil fertility on the one hand; on the other hand, it can introduce beneficial microbial flora, improve the soil microbial flora environment, and create a soil environment that is conducive to the growth and development of crops, which has a positive significance for increasing crop yield and income, and also facilitates the degradation and harmless treatment of biodegradable film.

[0049] In summary, soil conditioners made from porous biochar-based microspheres, biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules have better advantages in soil remediation.

[0050] The method for preparing the soil conditioner provided by this invention is achieved through the following technical solution:

[0051] A method for preparing a soil conditioner includes the following steps:

[0052] Step 1: Preparation of food sludge-based biochar;

[0053] Step 2: After accurately measuring and mixing food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder, the mixture is placed in a granulator for granulation to obtain porous biochar-based microspheres with a particle size of 0.5-2 cm.

[0054] Step 3: Mix the biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules with the porous biochar-based microspheres from Step 2 according to the specified ratio to obtain the soil conditioner composition.

[0055] The organic complexes contained in the biodegradable organic complex capsules in the soil conditioner composition are selected according to the acidity or alkalinity of the soil to be treated.

[0056] When the soil to be improved is acidic, the organic complex contained in the biodegradable organic complex capsule is an alkaline organic complex.

[0057] When the soil to be improved is alkaline, the organic complex contained in the biodegradable organic complex capsule is an acidic organic complex.

[0058] The preparation method of the present invention is relatively simple, the granulation is easy, and it is easy to realize industrial production.

[0059] In summary, this application has the following advantages:

[0060] 1. This invention transforms food sludge into a valuable resource by using a specific pyrolysis process and single-atom sterilization and catalytic technology to treat the food sludge at high temperatures to render it harmless. The resulting food sludge-based carbon material has the advantages of high porosity, high surface area, and low heavy metal content, and can be used in the production of soil conditioners.

[0061] 2. The soil conditioner of this invention can adsorb and remove soluble heavy metal elements and aluminum elements, reduce the harm of heavy metals and aluminum toxicity, adjust the soil pH value, improve the soil structure and physical properties and water, soil and fertilizer retention capacity, thereby promoting the growth and development of crops and achieving the effect of increasing crop yield and income.

[0062] 3. The preparation method of the present invention is relatively simple, the granulation is easy, it is easy to realize industrial production, reduce the production cost of soil conditioner, gain a competitive price advantage for the product, and facilitate market promotion and application.

[0063] 4. Based on soil remediation survey information, the inventors formulated a soil conditioner by combining porous biochar-based microspheres, biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules. This conditioner has the functions of slow-release compound fertilizer gel, organic complex, and organic fertilizer, which prolongs the continuous remediation life of the soil conditioner, helps to improve the physical properties of the soil, enhances the soil's resistance to damage, and creates a soil environment suitable for crop growth and development, thereby achieving the goal of increasing crop yield and income. Detailed Implementation

[0064] To further understand the inventiveness of this invention, the technical solution of this invention is described and explained below with reference to embodiments and comparative examples. The specific embodiments are merely explanations of this application and are not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventiveness, but as long as they are within the scope of the claims of this invention, they are protected by patent law.

[0065] Example

[0066] A soil conditioner comprises at least porous biochar-based microspheres. These porous biochar-based microspheres are made from food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agents, and binders.

[0067] The single-atom modified zeolite agent accounts for 0.5–2.0 wt% of the total mass of the porous biochar-based microspheres. The specific dosage of the single-atom modified zeolite agent needs to be determined by testing the soil to be remediated for harmful microorganisms. When the soil to be remediated is medical waste or biologically contaminated soil, the addition amount of single-atom modified zeolite agent in the porous biochar-based microspheres should be controlled at 1.5–2.0 wt%. For the remediation of common soils with continuous cropping obstacles, or acidic or alkaline soils, where harmful microorganisms are relatively few, the addition amount of single-atom modified zeolite agent in the porous biochar-based microspheres should be controlled at 0.5–1.0 wt%. In the small-scale test, the addition amount of single-atom modified zeolite agent was 1.0 wt%.

[0068] The single-atom modified zeolite agent can be synthesized by Guangxi Lianke Hua New Materials Co., Ltd. or Beijing Single Atom Catalysis Technology Co., Ltd. The surface and pores of the single-atom modified zeolite agent are loaded with single-atom metals through chemical bonds. These single-atom metals include at least one of Fe, Ag, Cu, Zn, Ce, and Ti. The porous zeolite agent carrier is selected as 4A zeolite powder with an average particle size of 0.5-50 micrometers. Preferably, the porous zeolite agent carrier is 4A zeolite powder with a particle size distribution of 20-38 micrometers. The 4A zeolite powder is first sieved through a 400-mesh sieve, and the resulting sieved material is then sieved through a 625-mesh sieve. The material remaining on the 625-mesh sieve is 4A zeolite powder with a particle size distribution of 20-38 micrometers.

[0069] To facilitate understanding of the preparation technology of single-atom modified zeolite agents, the following preparation method is provided: First, 4A zeolite powder with a particle size distribution of 20-38 μm is calcined and activated at 200℃ for 2 hours and set aside. Then, an aqueous solution of 10-20 g / L acetylacetone salts (acetylacetone iron, acetylacetone silver, acetylacetone copper, acetylacetone zinc, acetylacetone cerium, acetylacetone titanium) is added to the 4A zeolite powder with a particle size distribution of 20-38 μm at a dropping rate of 80-120 μL / second. The metal content in the acetylacetone salt solution accounts for 0.5% of the total mass ratio of the metals in the 4A zeolite powder and the acetylacetone salt solution. The solution is diluted to -5wt% and then ultrasonically treated at a frequency of 40-100kHz for 30-60 minutes to disperse it evenly. The mixture is then stirred at 80-120r / min for 12-16 hours. The resulting mixture is heated to the boiling point of water to evaporate the solvent. The solvent is then thoroughly ground in a planetary ball mill at 40-60r / min for 0.5-1 hour to obtain a solid powder. The solid powder is then heated in air at 400-420℃ for 2 hours, cooled to room temperature, and ground in a planetary ball mill at 60-80r / min for 10-30 minutes to obtain the final product.

[0070] Preferably, the single-atom metals are Fe and Ti, with a mass ratio of Fe to Ti of 2:1. The single-atom metal loading rate in the single-atom modified zeolite agent is 1–5 wt%. Preferably, the single-atom metal loading rate in the single-atom modified zeolite agent is 3–5 wt%. More preferably, the single-atom metal loading rate in the single-atom modified zeolite agent is 5 wt%, which makes the cost of using the single-atom modified zeolite agent relatively low under industrial mass production.

[0071] On the one hand, single-atom modified zeolite agents can play an excellent role in sterilization and disinfection in soil, effectively removing harmful pathogens (bacteria, viruses, etc.) from the soil. On the other hand, the porous structure of single-atom modified zeolite agents can adsorb organic pollutants. Under sunlight (specifically, ultraviolet rays), the single-atom metal can catalyze the decomposition of organic pollutants, thus playing a role in decomposing organic pollutants. At the same time, the porous structure of zeolite can also improve water and fertilizer retention, thereby enhancing soil remediation efficiency and effectively improving the physicochemical properties of the soil. In addition, the porous structure of single-atom modified zeolite agents can increase the content of exchangeable ions and also adsorb heavy metal ions, thus improving the soil's resistance to erosion, passivating heavy metals in the soil, reducing heavy metal pollution, reducing crop stress, and achieving the goal of increasing crop yield and income.

[0072] The binder accounts for 8-20 wt% of the total mass of the porous biochar-based microspheres. The binder is a key material in the granulation of porous biochar-based microspheres. The binder selected in this invention is a compound of a disintegrating organic binder and an inorganic binder. The inorganic binder is at least one of illite powder, bentonite powder, dolomite powder, diatomaceous earth powder, kaolin powder, montmorillonite powder, and attapulgite powder. All of the above inorganic binders have a porous structure, which can improve soil structure, increase soil fertility, improve soil structure, increase soil water retention and aeration, and enhance soil fertility and plant growth capacity.

[0073] To facilitate transportation and use, the porous biochar-based microspheres are designed with a particle size between 0.8 and 3.0 cm. However, a particle size of 0.8-3.0 cm is not advantageous for soil remediation. The smaller the microspheres, the greater their contact area with the soil, resulting in higher soil remediation efficiency. Therefore, a disintegrating organic binder is added to the binder of the porous biochar-based microspheres. The disintegrating organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid. This binder disintegrates in water under external moisture erosion, allowing the porous biochar-based microspheres to disintegrate into smaller microspheres. This results in a larger contact area between the microspheres and the soil, effectively improving soil remediation efficiency.

[0074] Preferably, the binder is made of kaolin powder and starch, and the starch content in the binder is controlled at 20-40 wt%. Kaolin powder and starch are widely available and have relatively low procurement costs. Under the premise of ensuring the soil remediation effect, the production cost of the porous biochar-based microspheres is controlled, thereby enhancing the product's competitive advantage.

[0075] Food wastewater sludge, a byproduct of food industry wastewater treatment, contains various components including organic matter, inorganic matter, and microorganisms, as well as harmful organic matter, heavy metals, and pathogens. It requires specialized treatment; improper handling can lead to severe environmental damage and secondary pollution, imposing a heavy burden on the environment and the economy. The core technical solution of this invention is to address the pollution problem of food wastewater sludge by using high-temperature pyrolysis to obtain food wastewater sludge-based carbon materials for the production of soil conditioners.

[0076] Food sludge-based biochar materials contain relatively less inorganic carbon (SIC) and organic carbon (SOC) compared to cellulose-based biochar. In soil remediation, exogenous supplementation of SIC and SOC can improve soil fertility and erosion resistance, thus benefiting crop yields. Therefore, the biochar in porous biochar-based microspheres is a blend of food sludge-based and cellulose-based biochar. The total mass of both types accounts for 78–90 wt% of the total mass of the porous biochar-based microspheres. The mass ratio of food sludge-based biochar to cellulose-based biochar is (1–4):(1–4). Preferably, the mass ratio is 3:1.

[0077] Numerous studies have documented information on cellulose-based biochar, which is produced by the pyrolysis of cellulose-rich waste biomass materials. Cellulose-rich waste biomass materials include at least one of the following: rice straw, wheat straw, corn straw, sorghum straw, reed straw, waste sawdust, shredded dead branches, shredded dead bark, shredded leaves, shredded dead grass, shredded coconut shells, bagasse, coffee grounds, and peanut shell residue. Cellulose-based biochar materials can be directly purchased from existing sources (such as corn straw biochar from Henan Xingnuo Environmental Protection Materials Co., Ltd., and corn, wheat, and rice straw biochar from Henan Jiahe Water Purification Materials Co., Ltd.), or customized production can be commissioned to other companies.

[0078] Food sludge-based biochar is produced by the pyrolysis of food sludge. It's important to note that existing technologies also exist for pyrolyzing sludge into biochar, such as thermal degradation in an inert atmosphere, with pyrolysis temperatures ranging from 300-1000℃. This process converts wastewater sludge into fixed carbon, ash, bio-oil, combustible gases, and water vapor. However, existing sludge treatment technologies have the following problems: 1. The porosity of biochar is inversely proportional to the pyrolysis temperature. To obtain biochar materials with high porosity, the pyrolysis temperature must be too low, resulting in incomplete elimination and decomposition of harmful pathogens and organic pollutants in the sludge. Conversely, while higher pyrolysis temperatures achieve relatively thorough elimination and decomposition of harmful pathogens and organic pollutants, they affect the porosity of the biochar material, ultimately impacting the remediation effect of soil conditioners. Furthermore, residual heavy metal particles can easily cause secondary pollution. Therefore, the inventors provide a method for preparing food sludge-based biochar materials that efficiently removes heavy metal particles and achieves relatively high porosity and specific surface area. The specific preparation method is as follows:

[0079] Step 1: Take 10 parts of food sludge and mix it evenly with 90-190 parts of water to obtain a sludge suspension;

[0080] Step 2: While stirring at 100-300 rpm, add an organic complex to the sludge suspension. The organic complex accounts for 0.01-0.10 wt% of the food sludge mass. Divide the organic complex into at least three portions, with an interval of 15-30 min between each portion. After the organic complex is added, continue stirring at 100-300 rpm for 30-60 min.

[0081] The organic complex is at least one of aminocarboxylic acid salts and organophosphonates.

[0082] Aminocarboxylic acid salt organic complexes include trisodium aminotriacetate, sodium EDTA, ethylenediaminetetraacetic acid (TEA), pentasodium diethylenetriaminepentacarboxylic acid, etc. Organophosphonate organic complexes include heptasodium diethylenetriaminepentamethylenephosphonate, pentasodium ethylenediaminetetramethylenephosphonate, hexasodium hexamethylenediaminetetramethylenephosphonate, etc.

[0083] The amount of organic complex added depends on the content of heavy metal ions measured in the sludge suspension. The organic complex is added in excess, that is, the actual added mass of organic complex is 1.05-1.1 times the standard complexing amount of organic complex with heavy metal ions. The organic complex effectively removes heavy metal ions.

[0084] Step 3: Add a pH adjuster to the sludge suspension. The pH adjuster is tartaric acid and / or phosphoric acid. After adding the pH adjuster, adjust the pH of the sludge suspension to 6.8-7.1. Add magnetic single-atom modified halloysite to disinfect harmful pathogens and effectively passivate heavy metal particles. The magnetic single-atom modified halloysite accounts for 0.05-0.50 wt% of the food sludge mass. The amount of magnetic single-atom modified halloysite added depends on the content of harmful pathogens in the sludge suspension. In the small-scale test, 0.05 wt% magnetic single-atom modified halloysite can effectively remove more than 95% of harmful pathogens. Divide the magnetic single-atom modified halloysite into at least three portions. The interval between two portions of magnetic single-atom modified halloysite is 15-30 min. After the magnetic single-atom modified halloysite is added, continue stirring at 100-300 rpm for 30-60 min.

[0085] Step 4: Let the water stand under ultraviolet light for 12-24 hours, then extract the upper layer of water to the sewage network. The upper layer of water, after being treated with organic complex and magnetic single-atom modified halloysite, has a relatively low content of heavy metal ions and harmful pathogens. It can be directly discharged into the sewage network or used as the feed water in Step 1. The food sludge treated with organic complex and magnetic single-atom modified halloysite is then subjected to dry-wet separation to obtain food sludge granules with a water content of 25-40 wt%.

[0086] Step 5: Place the food sludge granules from Step 4 in an oven and dry them at 120-160℃ to ensure the moisture content is below 3.0%. Then grind and crush the dried food sludge granules to obtain crushed food sludge material. Perform magnetic separation on the crushed food sludge material. After magnetic separation, separate the recovered magnetic single-atom modified halloysite and the crushed food sludge material to be pyrolyzed. Preferably, perform gravity sieving on the obtained crushed food sludge material to be pyrolyzed to remove heavy metal organic complexes.

[0087] Step six involves pyrolyzing the crushed food sludge from step five to obtain food sludge-based biochar with high specific surface area and high porosity. Specifically, 100 parts of the crushed food sludge from step five are weighed and mixed evenly with 0.5-2 parts of ammonia-thiourea, then placed in a muffle furnace for pyrolysis. The ammonia-thiourea, at 225-230℃, is fractionated into ammonia and hydrogen sulfide gases, which introduce nitrogen and sulfur functional sites, amino groups, sulfur-containing functional groups, and carboxyl functional groups onto the surface of the biochar, improving the passivation and elimination performance of the final food sludge-based biochar. Under a nitrogen atmosphere, the temperature is initially increased at 5-10℃ / min. The mixture is heated at a rate of 10-20℃ / min to 225-230℃ and held for 5-10 minutes. Then, it is heated at a rate of 10-20℃ / min to 360-420℃ and held for 40-50 minutes. Next, it is heated at a rate of 5-10℃ / min to 560-650℃ and held for 10-15 minutes. Finally, it is heated at a rate of 5-10℃ / min to 160-240℃ and then allowed to cool naturally to room temperature. The resulting solid is then ball-milled to refine it, thus obtaining food sludge-based biochar. Through the above specific pyrolysis process, food sludge-based biochar with high porosity, high specific surface area, and low heavy metal particle content can be obtained.

[0088] Preferably, in step six, 100 parts of the crushed food sludge to be pyrolyzed are weighed and mixed evenly with 1.2-1.6 parts of thiourea and placed in a muffle furnace for pyrolysis. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 10°C / min and held for 10 min, then heated to 400-420°C at a heating rate of 20°C / min and held for 45 min, then heated to 580-600°C at a heating rate of 10°C / min and held for 15 min, and finally heated to 180-200°C at a cooling rate of 10°C / min and allowed to cool naturally to room temperature. The resulting solid is then ball-milled to obtain food sludge-based biochar.

[0089] The magnetic single-atom modified halloysite in step three can be recycled by magnetic separation in step five. The recovery rate of magnetic single-atom modified halloysite is over 75%, which effectively reduces the production cost of food sludge-based biochar.

[0090] Magnetic single-atom modified halloysite can be synthesized by Guangxi Lianke Hua New Materials Co., Ltd. or Beijing Single Atom Catalysis Technology Co., Ltd. Magnetic single-atom modified halloysite comprises single-atom modified halloysite and nano-magnetic particles grafted onto the surface of the single-atom modified halloysite. The loading rate of nano-magnetic particles in the magnetic single-atom modified halloysite is 0.5-5 wt%. Commercially available nano-ferric oxide with a particle size of 5-30 nm is acceptable. The loading rate of nano-ferric oxide affects the recovery rate of magnetic single-atom modified halloysite; with a nano-magnetic particle loading rate of 3-5 wt%, the recovery rate of magnetic single-atom modified halloysite can reach over 85%.

[0091] Single-atom modified halloysite can be synthesized by Guangxi Lianke Hua New Materials Co., Ltd. or Beijing Single-Atom Catalysis Technology Co., Ltd. Single-atom modified halloysite comprises halloysite with an average particle size of 0.5-20 micrometers and single-atom metals supported on the surface and pore walls of the halloysite. The single-atom metals include at least one selected from Fe, Ag, Cu, Zn, Ce, and Ti, with a single-atom metal loading rate of 1-5 wt%. Preferably, the single-atom metals are Fe, Ag, and Ti, with a mass ratio of Fe, Ag, and Ti of 5:2:3. Single-atom modified halloysite can sterilize and decompose organic pollutants. The single-atom metal loading rate affects the sterilization and disinfection ability of magnetic single-atom modified halloysite; a single-atom metal loading rate of 2-5% is preferred.

[0092] The preparation method of magnetic single-atom modified halloysite is as follows:

[0093] Step 1, Preparation of single-atom modified halloysite:

[0094] S1.1, Halloysite is ball-milled to an average particle size of 0.5-20 μm and then calcined and activated at 180-200℃ for 1-2 h;

[0095] S1.2, add halloysite with an average particle size of 0.5-20 micrometers to an aqueous solution of 10-20 g / L acetylacetone salts (acetylacetone iron, acetylacetone silver, acetylacetone copper, acetylacetone zinc, acetylacetone cerium, acetylacetone titanium) at a dropping rate of 80-120 μL / s. The metal content in the acetylacetone salt solution accounts for 0.5-5 wt% of the total mass ratio of the metals in the halloysite and acetylacetone salt solution. The resulting solution is ultrasonically dispersed at an ultrasonic frequency of 40-100 kHz for 0.5-1 h, and then the mixed solution is stirred at 60-100 r / min for 12-16 h.

[0096] The mixed solution obtained in S1.3 and S1.2 is heated to the boiling point of water, evaporated at high temperature, and the solvent is dried. The solution is then thoroughly ground in a planetary ball mill at a speed of 40-60 r / min for 0.5-1.0 hours to obtain a solid powder.

[0097] S1.4 The obtained solid powder is heated in air at 360-400℃ for 2-3 hours, cooled to room temperature and then placed in a planetary ball mill and ground at 40-80 r / min for 30-60 min to obtain single-atom modified halloysite. The particle size of single-atom modified halloysite is controlled by the planetary ball mill speed and time.

[0098] Step 2: Mix 10 parts of single-atom modified halloysite and 40-90 parts of 0.5-2wt% epoxy silane aqueous solution evenly and then perform ultrasonic dispersion treatment for 0.5-1h. After ultrasonic dispersion treatment, filter under reduced pressure and vacuum dry the resulting solid to obtain epoxy silane grafted modified single-atom modified halloysite.

[0099] Step 3: Mix 10 parts of nanomagnetic particles and 40-90 parts of aminosilane aqueous solution with a concentration of 0.5-2wt% evenly, and then perform ultrasonic dispersion treatment for 0.5-1h. After ultrasonic dispersion treatment, filter under reduced pressure, and then vacuum dry the resulting solid to obtain aminosilane grafted modified nanomagnetic particles.

[0100] Step 4: Disperse 10 parts of epoxy silane-grafted modified single-atom halloysite and 0.053-0.53 parts of amino silane-grafted modified nanomagnetic particles in 90-190 parts of polar aprotic organic solvent (such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEMA), dimethyl sulfoxide (DMSO), acetone, etc.) until homogeneous. Heat to 45-60℃ and maintain at 45-60℃ for 1-4 hours for ultrasonic dispersion treatment. The ultrasonic dispersion frequency is 30-44kHz and the ultrasonic dispersion power is 200-600W. After ultrasonic dispersion treatment, perform vacuum filtration and vacuum drying of the filtered material. The resulting solid is ball-milled to obtain magnetic single-atom modified halloysite. The nanomagnetic particles are grafted onto the surface of the single-atom modified halloysite through amide bonds.

[0101] A method for preparing a soil conditioner includes the following steps: first, food sludge-based biochar is prepared; then, accurately measured food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder are mixed evenly and placed in a granulator for granulation to obtain porous biochar-based microspheres with a particle size of 0.8-3 cm, which is the soil conditioner.

[0102] To reduce the production cost of porous biochar-based microspheres while improving soil remediation effects, the porous biochar-based microspheres are also incorporating calcined shell powder and porous coal gangue powder.

[0103] In the porous biochar-based microsphere formulation, calcined shell powder accounts for 5–10 wt% of the total mass of the porous biochar-based microspheres, and porous coal gangue powder accounts for 5–10 wt% of the total mass of the porous biochar-based microspheres. Single-atom modified zeolite agent accounts for 0.5–2.0 wt% of the total mass of the porous biochar-based microspheres. Binder accounts for 8–20 wt% of the total mass of the porous biochar-based microspheres. The total mass of food sludge-based biochar and cellulose-based biochar accounts for 58–80 wt% of the total mass of the porous biochar-based microspheres. The mass ratio of food sludge-based biochar to cellulose-based biochar is (1–4):(1–4), with a preferred mass ratio of 3:1.

[0104] To address different soil types (acidic and alkaline soils) and promote crop yield increases, soil conditioners are formulated using porous biochar-based microspheres, biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules. The amount of porous biochar-based microspheres added to the soil conditioner is 75-90 wt%. The amount of biodegradable compound fertilizer capsules added is 4-10 wt%. The amount of biodegradable organic complex capsules added is 2-10 wt%. The amount of biodegradable organic fertilizer capsules added is 4-10 wt%. The preparation method of the above soil conditioner includes the following steps:

[0105] Step 1: Preparation of food sludge-based biochar;

[0106] Step 2: After accurately measuring and mixing food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder, the mixture is placed in a granulator for granulation to obtain porous biochar-based microspheres with a particle size of 0.8-3 cm.

[0107] Step 3: Mix the biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules with the porous biochar-based microspheres from Step 2 according to the specified ratio to obtain the soil conditioner composition.

[0108] The organic complexes contained in the biodegradable organic complex capsules in the soil conditioner composition are selected according to the acidity or alkalinity of the soil to be treated.

[0109] When the soil to be improved is acidic, the organic complexes contained in the biodegradable organic complex capsules are alkaline organic complexes, such as aminocarboxylic acid salt organic complexes: trisodium triamcinate, sodium EDTA, ethylenediaminetetraacetic acid (TEA), pentasodium diethylenetriaminepentacarboxylate, etc.

[0110] When the soil to be improved is alkaline, the organic complexes contained in the biodegradable organic complex capsules are acidic organic complexes, such as complex acids: tartaric acid, citric acid, phosphoric acid, hexamethylenediaminetetramethylphosphonic acid, phosphoric acid, etc.

[0111] The biodegradable compound fertilizer capsule includes a biodegradable coating film and compound fertilizer filled within the coating film. The coating film can be selected from polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly(3-hydroxyalkanoate) PHA, poly(ε-caprolactone) PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, carbon dioxide copolymer, etc., or a composite coating film composed of starch combined with at least one of the following: polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly(3-hydroxyalkanoate) PHA, poly(ε-caprolactone) PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, and carbon dioxide copolymer.

[0112] The coating film is preferably made of polyvinyl alcohol (PVA) and starch. PVA has a degree of polymerization of 2200-2400, a molecular weight of 80,000-90,000, and a degree of hydrolysis of 97%. The function of the biodegradable compound fertilizer capsules is that, under water erosion, the outer coating film ruptures, releasing the compound fertilizer gel, effectively improving soil fertility and promoting crop growth and development. Alternatively, the coating film is preferably...

[0113] Compound fertilizers are formulated based on the micronutrient requirements of crops to repair the soil. Options include nitrogen fertilizers (such as ammonium nitrogen fertilizers, nitrate nitrogen fertilizers, and ammonium nitrate nitrogen fertilizers), potassium fertilizers (potassium chloride, potassium sulfate, potassium nitrate, monopotassium phosphate, potassium dihydrogen phosphate, potassium polyphosphate, potassium polyphosphate, organic potassium, and wood ash), phosphate fertilizers (such as superphosphate, triple superphosphate, monoammonium phosphate, and diammonium phosphate), magnesium fertilizers (such as magnesium sulfate, magnesium chloride, magnesite, dolomite, and calcium magnesium phosphate), boron fertilizers (such as borax, boric acid, boron-containing superphosphate, boron magnesium phosphate, fluid boron, sugar alcohol boron, amino acid boron, amino acid boron calcium fertilizer, boron calcium magnesium, and succinate boron), manganese fertilizers (such as manganese sulfate, manganese chloride, manganese oxide, and manganese carbonate), zinc fertilizers (such as zinc sulfate, zinc chloride, and zinc oxide), and molybdenum fertilizers (such as ammonium molybdate, sodium molybdate, molybdenum trioxide, and molybdenum disulfide). Ammonium nitrogen fertilizers include ammonium bicarbonate, ammonium sulfate, ammonium chloride, and ammonia water. Nitrate nitrogen fertilizers include sodium nitrate, calcium nitrate, and ammonium nitrate. Amide nitrogen fertilizers include urea. Appropriate water-retaining agents (humic acid copolymers, sodium polyacrylate, polyvinyl alcohol, polyglutamate-modified biochar, sodium polyacrylate-modified bentonite, etc.) can also be added to compound fertilizers.

[0114] Biodegradable organic complex capsules consist of a biodegradable coating film and an organic complex filling the coating film. When the soil to be improved is acidic, the organic complex contained in the biodegradable organic complex capsules is an alkaline organic complex, such as aminocarboxylic acid salts: trisodium triamcinate, sodium EDTA, ethylenediaminetetraacetic acid (TEA), pentasodium diethylenetriaminepentacarboxylate, etc. When the soil to be improved is alkaline, the organic complex contained in the biodegradable organic complex capsules is an acidic organic complex, such as complexed acids: tartaric acid, citric acid, phosphoric acid, hexamethylenediaminetetramethylenephosphonic acid, etc.

[0115] The coating film in the biodegradable organic complex capsules can be selected from polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly(3-hydroxyalkanoate) PHA, poly(ε-caprolactone) PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, carbon dioxide copolymer, etc., or a composite coating film composed of starch combined with at least one of polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly(3-hydroxyalkanoate) PHA, poly(ε-caprolactone) PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, and carbon dioxide copolymer. The preferred coating film is polyvinyl alcohol PVA and starch. The polyvinyl alcohol PVA has a degree of polymerization of 2200-2400, a molecular weight of 80,000-90,000, and a degree of alcoholysis of 97%.

[0116] The function of biodegradable organic complex capsules: Under water erosion, the outer biodegradable film of the biodegradable organic complex capsule breaks and slowly releases the organic complex. On the one hand, it can effectively complex and remove heavy metal particles and reduce the toxicity of heavy metal ions. On the other hand, by selecting organic complexes of different acid and base types, it can also adjust the soil pH value, improve the soil structure and physical properties, and create a soil environment suitable for the growth and development of crops, which has a positive significance for increasing crop yield.

[0117] Biodegradable organic fertilizer capsules consist of a biodegradable coating film and organic fertilizer filled within the coating film.

[0118] The coating film in the biodegradable organic fertilizer capsules can be selected from polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly(3-hydroxyalkanoate) PHA, poly(ε-caprolactone) PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, carbon dioxide copolymer, etc., or a composite coating film composed of starch combined with at least one of the following: polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly(3-hydroxyalkanoate) PHA, poly(ε-caprolactone) PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, and carbon dioxide copolymer. The preferred coating film is polyvinyl alcohol PVA and starch. The polyvinyl alcohol PVA has a degree of polymerization of 2200-2400, a molecular weight of 80,000-90,000, and a degree of alcoholysis of 97%.

[0119] The function of biodegradable organic fertilizer capsules: When the outer biodegradable film of the biodegradable organic fertilizer capsule breaks, it slowly releases organic fertilizer, which can improve soil fertility on the one hand; on the other hand, it can introduce beneficial microbial flora, improve the soil microbial flora environment, and create a soil environment that is conducive to the growth and development of crops, which has a positive significance for increasing crop yield and income, and also facilitates the degradation and harmless treatment of biodegradable film.

[0120] This soil conditioner composition, formulated with porous biochar-based microspheres, biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules, possesses the functions of slow-release compound fertilizer gel, organic complex, and organic fertilizer. It extends the continuous remediation lifespan of the soil conditioner, improves soil physical properties, enhances the soil's resistance to damage, and creates a soil environment conducive to crop growth and development, thereby increasing crop yields. Furthermore, this soil conditioner composition can reduce the frequency of fertilizer application for crops, and the slow-release compound fertilizer gel can meet the crop's growth needs, thus reducing fertilizer input costs.

[0121] Example 1: A soil conditioner is a porous biochar-based microsphere with a particle size of 10±1mm. The porous biochar-based microsphere is made of 67.5 parts food sludge-based biochar, 22.5 parts cellulose-based biochar (corn stalk biochar from Henan Xingnuo Environmental Protection Materials Co., Ltd.), 1 part single-atom modified zeolite agent (outsourced), 5.4 parts kaolin (325 mesh white calcined kaolin, purchased from Lingshou Zhuolei Building Materials Co., Ltd.), and 3.6 parts starch (industrial grade corn starch, purchased from Jinan Deqiao Chemical Technology Co., Ltd.).

[0122] The preparation method of magnetic single-atom modified halloysite (outsourced) is as follows:

[0123] Step 1, Preparation of single-atom modified halloysite:

[0124] S1.1, place halloysite (500 mesh halloysite powder, Lingshou County Nanyu Mineral Products Processing Plant) in a planetary ball mill and ball mill at 60 rpm for 10 minutes to obtain medium particle size D. 50 =16μm ultrafine halloysite was obtained and calcined and activated in a muffle furnace at 200℃ for 2 hours for later use;

[0125] S1.2, an aqueous solution of 20 g / L acetylacetone salt (1 L of acetylacetone salt solution contains 10 g of iron acetylacetone, 4 g of silver acetylacetone, and 6 g of titanium acetylacetone) is added to the medium-sized particle size D prepared in S1.1 at a dropping rate of 100 μL / s. 50=16μm ultrafine halloysite, the content of metal elements (iron + silver + titanium) in the acetylacetone salt solution is 2wt% of the total mass ratio of metal elements (iron + silver + titanium) in the ultrafine halloysite and the acetylacetone salt solution. The resulting solution is ultrasonically dispersed at an ultrasonic frequency of 100kHz for 1h, and then the mixed solution is stirred at 100r / min for 12h.

[0126] The mixed solution obtained in S1.3 and S1.2 is heated to the boiling point of water, evaporated at high temperature, and the solvent is dried. The solution is then thoroughly ground in a planetary ball mill at 60 r / min for 0.5 hours to obtain a solid powder.

[0127] S1.4 The obtained solid powder was heated in air at 400°C for 2 hours, cooled to room temperature, and then ground in a planetary ball mill at 50 r / min for 30 minutes to obtain medium particle size D. 50 =10μm single-atom modified halloysite;

[0128] Step 2: Mix 10 parts of the single-atom modified halloysite prepared in S1.4 and 90 parts of 1 wt% aqueous solution of γ-glycidyl oxypropyltrimethoxysilane (KH560) evenly and then perform ultrasonic dispersion treatment for 1 h. The ultrasonic frequency is 40 kHz and the power is 400 W. After ultrasonic dispersion treatment, the mixture is filtered under reduced pressure. The resulting solid is then vacuum dried at 85 °C for 4.0 h to obtain γ-glycidyl oxypropyltrimethoxysilane grafted modified single-atom modified halloysite.

[0129] Step 3: Mix 10 parts of nano-magnetic particles (nano-iron oxide with a particle size of 10-30nm, Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) and 90 parts of 1.5wt% aqueous solution of γ-aminopropyltriethoxysilane (KH550) evenly and then perform ultrasonic dispersion treatment for 1 hour. The ultrasonic frequency is 40kHz and the power is 400W. After ultrasonic dispersion treatment, the mixture is filtered under reduced pressure. The resulting solid is vacuum dried at 85℃ for 4.0 hours to obtain γ-aminopropyltriethoxysilane grafted modified nano-magnetic particles.

[0130] Step 4: Disperse 10 parts of epoxysilane-grafted modified single-atom halloysite and 0.4 parts of γ-aminopropyltriethoxysilane-grafted modified nanomagnetic particles from Step 3 in 150 parts of N,N-dimethylformamide. Mix thoroughly, heat in a water bath to 50°C, and maintain at 50°C for 90 min of ultrasonic dispersion treatment. The ultrasonic dispersion frequency is 40 kHz and the ultrasonic dispersion power is 400 W. After ultrasonic dispersion treatment, perform vacuum filtration. Vacuum dry the obtained filter material at 85°C for 4.0 h. Place the obtained solid material in a planetary ball mill for ball milling refinement treatment. The ball milling speed is 60 rpm and the ball milling time is 15 min. After ball milling refinement, medium particle size D is obtained. 50 Magnetic single-atom modified halloysite with a diameter of 10 μm.

[0131] The specific preparation method of food sludge-based biochar is as follows:

[0132] Step 1: Take 10L of food sludge and 190L of tap water and pour them into a 300L stainless steel reactor. Adjust the speed to 300rpm and stir for 1 hour to obtain a sludge suspension.

[0133] Step 2: While stirring at 300 rpm, add 8g of pentasodium diethylenetriaminepentacarboxylate (CAS: 140-01-2) to the sludge suspension in the stainless steel reactor. Divide the pentasodium diethylenetriaminepentacarboxylate into four equal portions, each with a mass of 2g. Add two portions of pentasodium diethylenetriaminepentacarboxylate at an interval of 15min. After the organic complex is formed, continue stirring at 300 rpm for 30min.

[0134] Step 3: Add tartaric acid, a pH adjuster, to the sludge suspension. After adding the pH adjuster, adjust the pH of the sludge suspension to 7.0. Add 15g of magnetic single-atom modified halloysite to disinfect harmful pathogens and effectively passivate heavy metal particles. Divide the magnetic single-atom modified halloysite into three equal parts, each part weighing 5g. Add two parts of magnetic single-atom modified halloysite at an interval of 15min. After adding the magnetic single-atom modified halloysite, continue stirring at 300rpm for 30min.

[0135] Step 4: Turn on the ultraviolet lamp located at the top of the stainless steel reactor. Under ultraviolet light irradiation, stir at 300 rpm for 2 hours and then let stand for 12 hours. Extract the upper layer of water to the sewage network. The output upper layer of water, after being treated with organic complex and magnetic single-atom modified halloysite, has relatively low levels of heavy metal ions and harmful pathogens. It can be directly discharged into the sewage network or used as the feed water in Step 1. The food sludge treated with organic complex and magnetic single-atom modified halloysite is discharged from the bottom of the stainless steel reactor. The obtained food sludge is fed into a screw extrusion dry-wet separator for dry-wet separation to obtain food sludge granules. The measured water content of the food sludge granules is 32.4 wt%.

[0136] Step 5: Place the food sludge granules from Step 4 in an oven to ensure the moisture content is below ≤3.0%. Adjust the drying temperature to 150℃ and dry for 4.0 hours until the moisture content is 2.8%. Then, feed the dried food sludge granules into an industrial ball mill for grinding and crushing to obtain crushed food sludge material. Feed the crushed food sludge material into a belt-driven permanent magnet powder separator for magnetic separation. The belt-driven permanent magnet powder separator recovers magnetic single-atom modified halloysite, with a recovery rate of 85.6 wt%. The crushed food sludge material to be pyrolyzed from the belt-driven permanent magnet powder separator is fed into a wind-powered gravity separator for gravity screening to remove some heavy metal organic complexes, thus obtaining dried crushed food sludge material to be pyrolyzed.

[0137] Step Six: Place the crushed food sludge from Step Five into a muffle furnace for pyrolysis. Under a nitrogen atmosphere, first heat to 230℃ at a heating rate of 10℃ / min and hold for 10 min, then heat to 400℃ at a heating rate of 20℃ / min and hold for 45 min, then heat to 600℃ at a heating rate of 10℃ / min and hold for 15 min, and finally heat to 200℃ at a cooling rate of 10℃ / min and allow to cool naturally to room temperature. The resulting solid is then fed into an industrial ball mill for ball milling to refine the material, yielding a medium particle size D. 50 =20μm food sludge-based biochar, average pore size 10.8nm, specific surface area 364m² 2 / g. Food sludge-based biochar and cadmium-containing wastewater (Cb 2+ The solid-liquid ratio of the biochar (50 mg / L) was 0.1 g / L, the pH of the solution was 5.0, and the adsorption capacity of the food sludge-based biochar at 25℃ was 359 mg / L.

[0138] The specific preparation method of the single-atom modified zeolite agent is as follows: First, 4A zeolite powder with a particle size distribution of 20-38 μm is calcined and activated at 200℃ for 2 hours and set aside. Then, an aqueous solution of 18 g / L acetylacetone salt (1 L of acetylacetone salt solution contains 12 g of acetylacetone iron and 6 g of acetylacetone iron titanium) is added to the 4A zeolite powder with a particle size distribution of 20-38 μm at a dropping rate of 100 μL / second. The total mass of iron and titanium in the acetylacetone salt solution accounts for 4 wt% of the total mass ratio of iron + titanium in the 4A zeolite powder and the acetylacetone salt solution. The resulting solution was ultrasonically treated at 100 kHz for 30 min to disperse it evenly, and then stirred at 100 r / min for 12 h. The resulting solution was heated to the boiling point of water, evaporated at high temperature, and the solvent was dried. The solution was then thoroughly ground in a planetary ball mill at 50 r / min for 0.5 h to obtain a solid powder. The obtained solid powder was heated in air at 400 °C for 2 h, cooled to room temperature, and then ground in a planetary ball mill at 60 r / min for 10 min to obtain a medium particle size D. 50 Single-atom modified zeolite agent with a diameter of 25 μm.

[0139] A method for preparing a soil conditioner is as follows: 67.5 parts of food sludge-based biochar, 22.5 parts of cellulose-based biochar, 1 part of single-atom modified zeolite agent, 5.4 parts of 325-mesh white calcined kaolin, and 3.6 parts of industrial-grade corn starch are placed in a high-speed dispersion kettle and dispersed and mixed at 400 rpm for 1 hour. After uniform mixing, the resulting mixture is placed in an HLSG-50 wet mixing granulator for granulation to obtain porous biochar-based microspheres with a particle size of 10±1 mm, which is the soil conditioner.

[0140] To investigate the effect of the content of nano-ferric oxide in magnetic single-atom modified halloysite on the yield of magnetic single-atom modified halloysite in step five of the food sludge-based biochar preparation process, experimental examples 2-4 and comparative examples 1-2 were used to study the food sludge-based biochar preparation process.

[0141] The difference between Example 2 and Example 1 is as follows: In step four of the method for preparing magnetic single-atom modified halloysite, 10 parts of epoxy silane-grafted modified single-atom modified halloysite and 0.06 parts of γ-aminopropyltriethoxysilane-grafted modified nanomagnetic particles from step three are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly. The mixture is then heated in a water bath to 50°C and maintained at 50°C for 90 minutes for ultrasonic dispersion. The ultrasonic dispersion frequency is 40kHz and the ultrasonic dispersion power is 400W. After ultrasonic dispersion, the mixture is filtered under reduced pressure. The resulting filter material is then vacuum dried at 85°C for 4.0 hours. The resulting solid is then ball-milled in a planetary ball mill at 60 rpm for 15 minutes. After ball milling, a medium particle size D is obtained. 50The magnetic single-atom modified halloysite with a particle size of 10 μm was prepared using the same steps as other preparation methods. In step five of the food sludge-based biochar preparation process, the recovery rate of the magnetic single-atom modified halloysite was 75.8%.

[0142] The difference between Example 3 and Example 1 is as follows: In step four of the method for preparing magnetic single-atom modified halloysite, 10 parts of epoxy silane-grafted modified single-atom modified halloysite and 0.31 parts of γ-aminopropyltriethoxysilane-grafted modified nanomagnetic particles from step three are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly. The mixture is then heated in a water bath to 50°C and maintained at 50°C for 90 minutes for ultrasonic dispersion. The ultrasonic dispersion frequency is 40kHz and the ultrasonic dispersion power is 400W. After ultrasonic dispersion, the mixture is filtered under reduced pressure. The resulting filter material is then vacuum dried at 85°C for 4.0 hours. The resulting solid is then ball-milled in a planetary ball mill at 60 rpm for 15 minutes. After ball milling, a medium particle size D is obtained. 50 The magnetic single-atom modified halloysite with a diameter of 10 μm was prepared using the same steps as other preparation methods. In step five of the food sludge-based biochar preparation process, the recovery rate of the magnetic single-atom modified halloysite was 83.8%.

[0143] The difference between Example 4 and Example 1 is as follows: In step four of the method for preparing magnetic single-atom modified halloysite, 10 parts of epoxy silane-grafted modified single-atom modified halloysite and 0.50 parts of γ-aminopropyltriethoxysilane-grafted modified nanomagnetic particles from step three are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly. The mixture is then heated in a water bath to 50°C and maintained at 50°C for 90 minutes for ultrasonic dispersion. The ultrasonic dispersion frequency is 40kHz and the ultrasonic dispersion power is 400W. After ultrasonic dispersion, the mixture is filtered under reduced pressure. The resulting filter material is then vacuum dried at 85°C for 4.0 hours. The resulting solid is then ball-milled in a planetary ball mill at 60 rpm for 15 minutes. After ball milling, a medium particle size D is obtained. 50 The magnetic single-atom modified halloysite with a diameter of 10 μm was prepared using the same steps as other preparation methods. In step five of the food sludge-based biochar preparation process, the recovery rate of the magnetic single-atom modified halloysite was 87.2%.

[0144] The difference between Comparative Example 1 and Example 1 is as follows: In step four of the method for preparing magnetic single-atom modified halloysite, 10 parts of epoxy silane-grafted modified single-atom modified halloysite and 0.02 parts of γ-aminopropyltriethoxysilane-grafted modified nanomagnetic particles from step three are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly. The mixture is then heated in a water bath to 50°C and maintained at 50°C for 90 minutes for ultrasonic dispersion. The ultrasonic dispersion frequency is 40kHz and the ultrasonic dispersion power is 400W. After ultrasonic dispersion, the mixture is filtered under reduced pressure. The resulting filter material is then vacuum dried at 85°C for 4.0 hours. The resulting solid is then ball-milled in a planetary ball mill at 60 rpm for 15 minutes. After ball milling, a medium particle size D is obtained. 50 The magnetic single-atom modified halloysite with a diameter of 10 μm was prepared using the same steps as other preparation methods. In step five of the food sludge-based biochar preparation process, the yield of the recovered magnetic single-atom modified halloysite was 25.4%.

[0145] The difference between Comparative Example 2 and Example 1 is as follows: In step four of the preparation method of magnetic single-atom modified halloysite, 10 parts of epoxy silane-grafted modified single-atom modified halloysite and 0.6 parts of γ-aminopropyltriethoxysilane-grafted modified nanomagnetic particles from step three are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly. After heating to 50°C in a water bath, ultrasonic dispersion is performed at 50°C for 90 minutes. The ultrasonic dispersion frequency is 40kHz and the ultrasonic dispersion power is 400W. After ultrasonic dispersion, the material is filtered under reduced pressure. The resulting filter material is then vacuum dried at 85°C for 4.0 hours. The resulting solid is then ball-milled in a planetary ball mill at 60 rpm for 15 minutes. After ball milling, medium particle size D is obtained. 50 The magnetic single-atom modified halloysite with a particle size of 10 μm was prepared using the same steps as other preparation methods. In step five of the food sludge-based biochar preparation process, the recovery rate of the magnetic single-atom modified halloysite was 87.6%.

[0146] A comparison of Examples 1-4 and Comparative Examples 1-2 shows that when the loading rate of the nanomagnetic particles is controlled at 0.5-5 wt%, the recovery rate of magnetic single-atom modified halloysite is relatively high, which can reduce the preparation cost of food sludge biochar. Preferably, when the loading rate of the nanomagnetic particles is controlled at 3-5 wt%, the recovery rate of magnetic single-atom modified halloysite can reach more than 80 wt%, which can effectively reduce the preparation cost of food sludge biochar.

[0147] To investigate the effects of the addition of magnetic single-atom modified halloysite and organic complexes on the physicochemical properties of the prepared food sludge-based biochar, comparative examples 3-4 were tested to illustrate the preparation process of food sludge-based biochar.

[0148] The difference between Comparative Example 3 and Example 1 is as follows: In the preparation method of food sludge-based biochar, step two involves stirring at 300 rpm for 75 minutes; in step three, calcium hydroxide is added to the sludge suspension, and the pH of the sludge suspension is adjusted to 7.0 after the pH adjuster is added. 15g of magnetic single-atom modified halloysite is added to disinfect harmful pathogens and effectively passivate heavy metal particles. The magnetic single-atom modified halloysite is divided into three equal parts, each with a mass of 5g. The interval between adding two parts of magnetic single-atom modified halloysite is 15 minutes. After the magnetic single-atom modified halloysite is added, stirring is continued at 300 rpm for 30 minutes. The remaining preparation steps are the same.

[0149] The difference between Comparative Example 4 and Example 1 is as follows: In step three of the method for preparing food sludge-based biochar, tartaric acid, a pH adjuster, is added to the sludge suspension. After the pH adjuster is added, the pH of the sludge suspension is adjusted to 7.0, and stirring is continued at 300 rpm for 60 minutes. In step five, the food sludge granules from step four are placed in an oven to ensure that the moisture content of the food sludge granules is less than ≤3.0%. The drying temperature is adjusted to 150℃ and the drying process is carried out for 4.0 hours, resulting in a moisture content of 2.8% in the food sludge granules. The dried food sludge granules are then fed into an industrial ball mill for grinding and crushing to obtain crushed food sludge material. The crushed food sludge material is then subjected to gravity sieving and fed into a wind-powered gravity separator for gravity sieving to remove some heavy metal organic complexes, thus obtaining dried crushed food sludge material to be pyrolyzed. The remaining preparation steps are the same.

[0150] The heavy metal content in the raw material - food sludge - was determined (the heavy metal element content is as follows: Pb 238.4 mg / kg, Cb 6.9 mg / kg, Hg 3.3 mg / kg, Cr 68.6 mg / kg, As 15.2 mg / kg, total heavy metal content (M1) 332.4 mg / kg).

[0151] The heavy metal content of the food sludge-based biochar in Example 1 and Comparative Examples 3-4 was determined, including Pb, Cb, Hg, Cr, As, and the total heavy metal content M2. The heavy metal removal rate P due to the pyrolysis process was calculated as (332.4 - M2) * 100 / 332.4. To clearly demonstrate the effects of the addition of magnetic single-atom modified halloysite and organic complexes on the physicochemical properties of the prepared food sludge-based biochar, the test parameters were compiled and tabulated. See Table 1: Heavy Metal Content Parameters in Food Sludge-Based Biochar of Example 1 and Comparative Examples 3-4.

[0152] Table 1: Heavy metal content parameters in food sludge-based biochar from Example 1 and Comparative Examples 3-4

[0153]

[0154]

[0155] Based on the comparison of Example 1 and Comparative Examples 3-4 and Table 1, it can be seen that the combined use of magnetic single-atom modified halloysite and organic complex can reduce the heavy metal content in food sludge-based biochar.

[0156] Heavy metal removal test of food sludge-based biochar: using Cb 2+ Cr 3+ , Pb 2+ Standard solutions, each with a mass concentration of 1000 mg / L, were diluted 10-fold to prepare a mixed standard solution. The Cb concentration in the solution was measured using ICP. 2+ Cr 3+ , Pb 2+ The concentrations of the active ingredients were 102.5 mg / L, 98.9 mg / L, and 104.3 mg / L, respectively. The pH of the solution was adjusted to 6. 60 mL of this solution and 0.10 g of biochar were added to separate 100 mL centrifuge tubes. The mixture was shaken and adsorbed at room temperature for 24 h. After filtration through filter paper, the Cb concentration in the solution was determined by ICP. 2+ Cr 3+ , Pb 2+ The mass concentration of heavy metals was determined, and the removal rate and amount of heavy metals by food sludge-based biochar were calculated. The experimental results are shown in Table 2.

[0157] Table 2: Heavy metal removal parameters of food sludge-based biochar in Example 1 and Comparative Examples 3-4

[0158] <![CDATA[Cb 2+ Removal rate (%) <![CDATA[Cr 3+ Removal rate (%) <![CDATA[Pb 2+ Removal rate (%) Total removal rate (%) Example 1 40.2 98.5 96.1 78.2 Comparative Example 3 37.1 93.8 92.7 74.5 Comparative Example 4 35.9 94.6 93.5 74.7

[0159] As can be seen from the comparison of Example 1 and Comparative Examples 3-4 and Table 2, the residual heavy metal content in food sludge-based biochar has a negative impact on the heavy metal removal performance of food sludge-based biochar materials.

[0160] The difference between Example 5 and Example 1 is that in step six of the preparation method of food sludge-based biochar, 100 parts of the crushed food sludge to be pyrolyzed in step five are weighed and mixed evenly with 1.5 parts of thiourea. Under a nitrogen atmosphere, the mixture is first heated to 230°C at a heating rate of 10°C / min and held for 10 min, then heated to 400°C at a heating rate of 20°C / min and held for 45 min, then heated to 600°C at a heating rate of 10°C / min and held for 15 min, and finally heated to 200°C at a cooling rate of 10°C / min and allowed to cool naturally to room temperature. The resulting solid is then fed into an industrial ball mill for ball milling and refining to obtain a medium particle size D. 50=20μm food sludge-based biochar, with an average pore size of 10.2nm and a specific surface area of ​​369.2m². 2 / g. Food sludge-based biochar and cadmium-containing wastewater (Cb 2+ The solid-liquid ratio of the biochar prepared in Example 5 (50 mg / L) was 0.1 g / L, the solution pH was 5.0, and the adsorption capacity of the food sludge-based biochar at 25°C was 372 mg / L. The heavy metal removal parameters of the food sludge-based biochar prepared in Example 5 are as follows: Cb 2+ Removal rate 51.4%, Cr 3+ Removal rate 99.8%, Pb 2+ The removal rate was 99.5%, and the total removal rate was 83.6%. A comparison between Example 1 and Example 5 shows that adding thiourea to the pyrolysis process can improve the heavy metal removal capacity of the prepared food sludge-based biochar material.

[0161] The difference between Example 6 and Example 1 is that: one soil conditioner is a porous biochar-based microsphere with a particle size of 10±1mm. The porous biochar-based microsphere is made of 56.25 parts food sludge-based biochar, 18.75 parts cellulose-based biochar (corn stalk biochar from Henan Xingnuo Environmental Protection Materials Co., Ltd.), 8 parts calcined shell powder (325 mesh, from Lingshou County Kaiqi Mineral Products Processing Plant), 7 parts porous coal gangue powder (calcined 1250 mesh coal gangue powder, customized from Lingshou County Jingjia Mineral Products Processing Plant), 1 part single-atom modified zeolite agent (outsourced), 5.4 parts kaolin (325 mesh white calcined kaolin, purchased from Lingshou County Zhuolei Building Materials Co., Ltd.), and 3.6 parts starch (industrial grade corn starch, purchased from Jinan Deqiao Chemical Technology Co., Ltd.).

[0162] The difference between Example 7 and Example 5 is that: a soil conditioner is made from 85 parts of porous biochar-based microspheres prepared in Example 5, 6 parts of biodegradable compound fertilizer capsules, 3 parts of biodegradable organic complex capsules, and 6 parts of biodegradable organic fertilizer capsules.

[0163] The coating film of biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules is made of 20 parts starch and 80 parts polyvinyl alcohol (PVA), with the film thickness controlled at 80-100 micrometers.

[0164] The biodegradable compound fertilizer capsules contain a mixture of potassium dihydrogen phosphate, calcium nitrate, and diammonium phosphate in a 1:1:1 mass ratio. The capsules are manufactured using a coating process and have a particle size of 5-6 mm.

[0165] The organic complex in the biodegradable organic complex capsules is pentasodium diethylenetriaminepentacarboxylate. The biodegradable organic complex capsules are manufactured via a coating process, with a particle size of 5-6 mm.

[0166] The organic fertilizer in the biodegradable organic fertilizer capsule is sheep manure organic fertilizer YJF-012 from Dongying Kunbao Organic Fertilizer Co., Ltd. The biodegradable organic fertilizer capsule is produced by a coating machine and has a particle size of 5-6mm.

[0167] Soil amendments from Examples 1 and 5-7 were used in a soil remediation experiment. The experimental method was as follows: Ten samples of topsoil (0-30 cm) from the dyeing wastewater area surrounding the dyeing industrial park in Honghe Town, Xiuzhou District, Jiaxing City were randomly collected. These samples were air-dried, ground, sieved, and mixed to obtain soil samples to be remediated. The physicochemical properties of the soil samples were measured, recorded, and tabulated. The soil samples were then filled into the experimental area (3m long * 3m wide * 0.3m deep). 2kg of soil amendment was manually applied to the surface of the soil in the experimental area. The soil was then tilled to a depth of 10-15cm. Finally, the surface of the soil was sprayed with atomized water every 24 hours at a rate of 50g / m². 2 After seven days, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with each spraying amount being 50 g / m³. 2 After seven days, the physical and chemical properties of the soil were measured, recorded, and tabulated.

[0168] Table 3: Physicochemical properties of soil remediated by soil conditioners in Examples 1 and 5-7

[0169] Original soil Example 1 Example 5 Example 6 Example 7 organic matter g / kg 16.56 20.71 21.15 20.94 22.37 Pb content (mg / kg) 143.5 27.27 21.54 24.54 19.09 Cb content (mg / kg) 1.53 1.01 0.93 0.90 0.86 Hg content (mg / kg) 3.84 1.03 0.98 0.99 0.83 Cr content (mg / kg) 28.3 5.52 5.41 5.35 4.19 As content (mg / kg) 6.51 0.90 0.81 0.87 0.68 pH 4.87 6.15 6.07 6.28 6.57 catalase mL / g 3.15 3.87 3.94 4.06 4.13

[0170] Based on the comparison of Examples 1, 5-7 and Table 3, it can be seen that after 14 days of soil amendment application, soil fertility (organic matter) increased, harmful heavy metals such as lead, chromium, cadmium, mercury and arsenic were effectively adsorbed and reduced to below the risk control value, and the soil pH value increased by more than 1.20, effectively improving the physical and chemical properties of the soil.

[0171] To understand the long-term remediation effect of the soil remediation agent, a 7*9 day simulated soil remediation experiment was conducted using the soil conditioner in Example 5. Soil samples (3m long x 3m wide x 0.3m deep) were filled into the experimental area. 2kg of soil conditioner was manually applied to the surface of the soil in the experimental area, followed by a 10-15cm tillage. Then, the surface of the soil was sprayed with atomized water every 24 hours, with each spraying amount being 50g / m². 2 After seven days, the soil's physicochemical properties (T) were tested. 7d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2After seven days, the soil's physicochemical properties (T) were tested. 14d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 21d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 28d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 35d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 42d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 49d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 54d Then, the soil in the experimental area to be remediated was tilled to a depth of 10-15 cm, and atomized water was sprayed every 24 hours, with a spraying rate of 50 g / m² each time. 2 After seven days, the soil's physicochemical properties (T) were tested. 63d The physicochemical properties of soil T 7d To T 63d Conduct measurements, record data, and create tables.

[0172] Table 4: Parameters of the soil conditioner used in Example 5 during a 7*9 day simulated soil remediation experiment.

[0173]

[0174] As shown in Table 5, the soil conditioner in Example 5 showed an inflection point at 13-16 days. Within 16 days of application, the soil conditioner showed rapid adsorption and removal efficiency of heavy metals and could relatively quickly adjust the soil pH. Therefore, the following are the guidelines for using the soil conditioner in Example 5: When using the soil conditioner provided by this invention to remediate acidic medium-weight heavy metal contaminated soil, the soil remediation showed initial results after 14 days of use, and the soil remediation effect was more obvious after 35 days of use, which has met the requirements for planting common crops.

[0175] In summary, the soil conditioner of this invention can adsorb and remove heavy metal elements, adjust soil pH, improve soil structure and physicochemical properties, and enhance water, soil and fertilizer retention capacity. It can also effectively promote crop growth and development, thereby increasing crop yield and income.

Claims

1. A soil conditioner, characterized in that: The product includes porous biochar-based microspheres, which are made from food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agents, and binders. The food sludge-based biochar is produced by the pyrolysis of food sludge. The cellulose-based biochar is produced by the pyrolysis of cellulose-rich waste biomass materials. These cellulose-rich waste biomass materials include rice straw, wheat straw, corn straw, sorghum straw, reed straw, waste wood chips, shredded dead branches, shredded dead bark, shredded leaves, shredded dead grass, shredded coconut shells, bagasse, coffee grounds, and peanut shell residue. The single-atom modified zeolite agent comprises a porous zeolite agent carrier and a single-atom metal loaded on the surface and pore walls of the porous zeolite agent carrier, wherein the single-atom metal comprises at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the single-atom metal loading rate in the single-atom modified zeolite agent is 1-5 wt%; the binder is a disintegrating organic binder combined with at least one of illite powder, bentonite powder, dolomite powder, diatomite powder, kaolin powder, montmorillonite powder, and attapulgite powder; the disintegrating organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid. The preparation method of the food sludge-based biochar is as follows: Step 1: Take 10 parts of food sludge and mix it evenly with 90-190 parts of water to obtain a sludge suspension; Step 2: While stirring at 100-300 rpm, add an organic complex to the sludge suspension. The organic complex accounts for 0.01-0.10 wt% of the mass of the food sludge. Divide the organic complex into at least three portions, with an interval of 15-30 min between each portion. After the organic complex is added, continue stirring at 100-300 rpm for 30-60 min. Step 3: Add a pH adjuster to the sludge suspension to adjust the pH of the sludge suspension to 6.8-7.

1. Add magnetic single-atom modified halloysite, which accounts for 0.05-0.50 wt% of the mass of the food sludge. Divide the magnetic single-atom modified halloysite into at least three portions, with an interval of 15-30 minutes between two portions. After the magnetic single-atom modified halloysite is added, continue stirring at 100-300 rpm for 30-60 minutes. Step 4: After standing under ultraviolet light for 12-24 hours, the upper layer of water is extracted and sent to the sewage network. The food sludge, which has been treated with organic complex and magnetic single-atom modified halloysite, undergoes dry-wet separation to obtain food sludge granules with a moisture content of 25-40 wt%. Step 5: Dry the food sludge granules from Step 4 at 120-160℃ to reduce the moisture content to ≤3.0%. Then grind and crush the dried food sludge granules to obtain crushed food sludge material. Perform magnetic separation on the crushed food sludge material. After magnetic separation, separate the recovered magnetic single-atom modified halloysite and the crushed food sludge material to be pyrolyzed. Step six: Pyrolysis of the crushed food sludge material to be pyrolyzed in step five yields food sludge-based biochar with high specific surface area and high porosity. The preparation method of the magnetic single-atom modified halloysite is as follows: Step 1: Preparation of single-atom modified halloysite; Step 2: Mix 10 parts of single-atom modified halloysite and 40-90 parts of 0.5-2wt% epoxy silane aqueous solution evenly and then perform ultrasonic dispersion treatment for 0.5-1h. After ultrasonic dispersion treatment, filter under reduced pressure and vacuum dry the resulting solid to obtain epoxy silane grafted modified single-atom modified halloysite. Step 3: Mix 10 parts of nanomagnetic particles and 40-90 parts of aminosilane aqueous solution with a concentration of 0.5-2wt% evenly, and then perform ultrasonic dispersion treatment for 0.5-1h. After ultrasonic dispersion treatment, filter under reduced pressure, and then vacuum dry the resulting solid to obtain aminosilane grafted modified nanomagnetic particles. Step 4: Disperse 10 parts of epoxy silane-grafted modified single-atom halloysite and 0.053-0.53 parts of amino silane-grafted modified nanomagnetic particles in 90-190 parts of polar aprotic organic solvent, mix evenly, heat to 45-60℃, and maintain at 45-60℃ for 1-4 hours for ultrasonic dispersion treatment. The ultrasonic dispersion frequency is 30-44kHz and the ultrasonic dispersion power is 200-600W. After ultrasonic dispersion treatment, perform vacuum filtration, vacuum drying of the obtained filter material, and ball milling of the obtained solid material to obtain magnetic single-atom modified halloysite. The nanomagnetic particles are grafted onto the surface of single-atom modified halloysite through amide bonds.

2. The soil conditioner according to claim 1, characterized in that: The single-atom modified zeolite agent accounts for 0.5 to 2.0 wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8 to 20 wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 78 to 90 wt% of the total mass of the porous biochar-based microspheres; the mass ratio of the food sludge-based biochar to the cellulose-based biochar is (1 to 4):(1 to 4).

3. The soil conditioner according to claim 1, characterized in that: In step six, 100 parts of the crushed food sludge from step five are weighed and mixed evenly with 0.5-2 parts of thiourea. The mixture is then placed in a muffle furnace for pyrolysis. Under a nitrogen atmosphere, the mixture is first heated to 225-230℃ at a heating rate of 5-10℃ / min and held for 5-10 min. Then, it is heated to 360-420℃ at a heating rate of 10-20℃ / min and held for 40-50 min. Next, it is heated to 560-650℃ at a heating rate of 5-10℃ / min and held for 10-15 min. Finally, it is heated to 160-240℃ at a cooling rate of 5-10℃ / min and then allowed to cool naturally to room temperature. The resulting solid is then ball-milled to obtain food sludge-based biochar.

4. The soil conditioner according to claim 1, characterized in that: In step six, 100 parts of the crushed food sludge from step five are weighed and mixed evenly with 1.2-1.6 parts of thiourea. The mixture is then placed in a muffle furnace for pyrolysis. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 10°C / min and held for 10 min. Then, it is heated to 400-420°C at a heating rate of 20°C / min and held for 45 min. Next, it is heated to 580-600°C at a heating rate of 10°C / min and held for 15 min. Finally, it is heated to 180-200°C at a cooling rate of 10°C / min and then allowed to cool naturally to room temperature. The resulting solid is then ball-milled to refine the solid material, thus obtaining food sludge-based biochar.

5. A soil conditioner according to claim 1, characterized in that: The porous biochar-based microspheres further include calcined shell powder and porous coal gangue powder, with the calcined shell powder accounting for 5-10 wt% of the total mass of the porous biochar-based microspheres and the porous coal gangue powder accounting for 5-10 wt% of the total mass of the porous biochar-based microspheres; the single-atom modified zeolite agent accounting for 0.5-2.0 wt% of the total mass of the porous biochar-based microspheres; the binder accounting for 8-20 wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounting for 58-80 wt% of the total mass of the porous biochar-based microspheres; and the mass ratio of the food sludge-based biochar to the cellulose-based biochar being (1-4):(1-4).

6. A soil conditioner according to claim 1 or 5, characterized in that: The soil conditioner is composed of porous biochar-based microspheres, biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules; the amount of porous biochar-based microspheres added to the soil conditioner is 75-90 wt%; the amount of biodegradable compound fertilizer capsules added to the soil conditioner is 4-10 wt%; the amount of biodegradable organic complex capsules added to the soil conditioner is 2-10 wt%; and the amount of biodegradable organic fertilizer capsules added to the soil conditioner is 4-10 wt%.

7. A method for preparing the soil conditioner as described in claim 6, characterized in that: Includes the following steps: Step 1: Preparation of food sludge-based biochar; Step 2: After accurately measuring and mixing food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder, the mixture is placed in a granulator for granulation to obtain porous biochar-based microspheres with a particle size of 0.8-3 cm. Step 3: Mix the biodegradable compound fertilizer capsules, biodegradable organic complex capsules, and biodegradable organic fertilizer capsules with the porous biochar-based microspheres from Step 2 according to the specified ratio to obtain the soil conditioner composition. The organic complexes contained in the biodegradable organic complex capsules in the soil conditioner composition are selected according to the acidity or alkalinity of the soil to be treated. When the soil to be improved is acidic, the organic complex contained in the biodegradable organic complex capsule is an alkaline organic complex. When the soil to be improved is alkaline, the organic complex contained in the biodegradable organic complex capsule is an acidic organic complex.

Images