A biochar microbial activity soil conditioner and a method of making the same

Abstract

The application discloses a kind of biochar microbial activity soil conditioner and preparation method thereof, belong to microbial technical field.The conditioner of the application is prepared from the following weight parts of raw materials: modified sludge biochar 40-80 parts, peanut shell 10-20 parts, humic acid 10-20 parts, urea 5-10 parts, ammonium dihydrogen phosphate 5-10 parts, attapulgite 5-10 parts, microbial inoculant 1-4 parts, conditioner 0.1-0.5 parts.The sludge biochar of the application is prepared from municipal sludge as raw material, and the physical and chemical properties of sludge biochar are fully improved through steps such as drying pyrolysis modification, and the adsorption capacity of heavy metal ions is improved;The application compounding rose color kock's bacteria and thick hair flat leather fungus as functional microbial inoculant, synergistic effect, realize the effective fixation and degradation to common heavy metal elements in soil, make heavy metal into stable form to reduce migration and biological availability.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a biochar microbial activated soil conditioner and its preparation method. Background Technology

[0002] Human beings have continuously exploited Earth's resources to improve their living conditions. While the gross industrial and agricultural output has grown rapidly, the living environment (including water, soil, air, and organisms) has been deteriorating. Soil, as a primary source of human well-being, occupies a vital position in human activities and is the foundation of human survival. The deterioration of the soil environment is caused by a variety of factors, such as the emission of waste gas, wastewater, and waste residue during industrial production; the irrational use of pesticides and fertilizers in agricultural production; and the discharge of various types of sewage from urban life. Heavy metal pollution is one of the causes of soil environmental degradation. Metals with a specific gravity greater than 4 are generally called heavy metals, including Pb, Ni, Hg, Zn, Cd, As, and Cr. Heavy metals are also major pollutants affecting the quality of farmland.

[0003] There are many causes of heavy metal pollution in soil, with mining being one of the main ones. Heavy metal pollution in soil is characterized by its insidious nature, persistence, and irreversibility. It can reduce crop yields and accumulate through the food chain, having a significant impact on human health. Therefore, the remediation of heavy metal-contaminated soil is a challenging task. Currently, soil remediation technologies mainly fall into three categories: physical remediation, chemical remediation, and bioremediation. Among these, in-situ passivation remediation of heavy metal-contaminated soil has been widely studied by scientists due to its low cost, simple operation, and ease of promotion. The selection of passivating agents is also crucial in the passivation remediation process of heavy metal-contaminated soil. Passivating agents are divided into inorganic and organic passivating agents. Currently, the most widely used organic passivating agents are organic waste and biochar.

[0004] Currently, the remediation function of biochar for heavy metal contaminated soil has been recognized by most scholars and has received attention in the academic community. Han (Han L, Zhang E, Yang Y, et al. Highly efficient U(VI) removal by chemically modified hydrochar and pyrochar derived from animal manure; Journal of Cleaner Production, 2020, 264; 121542) et al. found that biochar made from animal manure increased its specific surface area by 3-6 times after NaOH treatment and significantly increased its adsorption capacity for uranium.

[0005] However, current research on biochar is relatively limited. Many biochar-based soil conditioners have only one function, merely physically adsorbing and fixing one type of metal ion. They are expensive to use and have a weak effect on regulating soil physicochemical properties and biological activity, failing to fundamentally solve soil problems. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by using waste municipal sludge and peanut shells as raw materials to prepare highly active biochar materials. At the same time, it is supplemented with microbial agents that efficiently degrade heavy metal ions. The two work together to reduce the content of heavy metal ions in the soil and effectively improve the enzyme activity of the soil, thereby fundamentally enhancing the biological activity of the soil and improving the efficiency of soil cultivation.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0008] A biochar microbial activated soil conditioner is prepared from the following raw materials in parts by weight: 40-80 parts modified sludge biochar, 10-20 parts peanut shells, 10-20 parts humic acid, 5-10 parts urea, 5-10 parts ammonium dihydrogen phosphate, 5-10 parts attapulgite, 1-4 parts microbial inoculant, and 0.1-0.5 parts conditioner.

[0009] Furthermore, the modified sludge biochar is obtained through drying, pyrolysis, and carbonization modification.

[0010] Furthermore, the method for preparing the modified sludge biochar is as follows:

[0011] (1) Dry the urban sludge at a temperature of 100-110℃ for 24-30 hours. After drying, break the sludge into solid sludge particles of 0.5-1mm.

[0012] (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:5-10, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 300-400℃ at a rate of 5-6℃ per minute, held at the temperature for 1 hour, and then raised to 500℃ at a rate of 1-2℃ per minute. After holding at the temperature for 5 hours, the temperature is naturally cooled to obtain sludge biochar.

[0013] (3) Disperse the sludge biochar obtained in step (2) in water at a solid-liquid ratio of 1 kg: 1 L, add 1-3 wt% ferric nitrate of sludge biochar, then add 3-8 wt% urea of ​​sludge biochar, keep at 60°C for 15-20 min, then add 1-3 wt% hexadecyltrimethylammonium bromide of sludge biochar, raise the temperature to 95-100°C and continue stirring until the solution becomes gel-like, transfer to a vacuum drying oven at 110-130°C for 5 h, and then calcine at 600°C for 3 h to obtain the final product modified sludge biochar.

[0014] Furthermore, the microbial inoculants are *Coprinus roseus* with accession number CGMCC1.15046 and *C. thunbergii* with accession number CCTCC AF 96007.

[0015] The present invention relates to Kocuria rosea, with accession number CGMCC1.15046, purchased from the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0016] The present invention relates to *Chrysosporium*, with accession number CCTCC AF 96007, purchased from the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0017] Furthermore, the preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium, centrifuged at 5000 r / min for 8-10 min, the supernatant is discarded to obtain the two bacterial cells, and then the two bacterial suspensions are prepared with physiological saline to form bacterial suspensions with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried.

[0018] The LB medium consists of: 2g trypsin, 1g trypsin mother powder, 2g sodium chloride, pH 7.4, diluted with distilled water to 200mL, and sterilized at 121℃ for 20min.

[0019] Furthermore, the conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:1.

[0020] A method for preparing a biochar microbial activated soil conditioner includes the following preparation steps:

[0021] (1) Preparation of modified sludge biochar;

[0022] (2) Preparation of microbial inoculants;

[0023] (3) Mix the modified sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

[0024] Further, the granulation method in step (3) is as follows: the disc angle is adjusted to 50°-60°, the rotation speed is adjusted to 5-10 r / min, and atomized water is sprayed while rotating. When particles with a diameter of 0.5-1 mm are produced, the spraying of atomized water is stopped, the rotation speed is adjusted to 40-60 r / min, and the rotation is fast until the particles are 1-3.5 mm in diameter.

[0025] The dosage and usage of the soil conditioner of this invention is 30-50 kg / mu.

[0026] Properly treating sludge from urban wastewater treatment plants and realizing its resource utilization is a major challenge facing my country's urbanization process. Current sludge treatment methods mainly include sanitary landfill, aerobic composting, anaerobic digestion, incineration, and pyrolysis carbonization. Among these, sludge pyrolysis carbonization technology has attracted much attention because it can achieve a significant reduction, harmlessness, and stabilization of sludge. Sludge biochar possesses the characteristics of biochar and has enormous potential for resource utilization.

[0027] However, current sludge biochar pyrolysis technology does not completely treat the pollutants it contains, resulting in poor pore size distribution of the biochar, with many dead and closed pores. In practical applications, its adsorption and fixation capacity is poor, and the resource utilization rate of sludge is not high.

[0028] Therefore, this invention involves drying and pyrolysis modification of sludge, followed by programmed heating and modification to increase the total pore volume and average pore size, resulting in a more developed pore structure, increased specific surface area, and richer surface functional groups. This significantly improves the quality and usability of the co-pyrolysis biochar product, effectively reducing toxic and harmful substances such as pathogens in the sludge. Simultaneously, it optimizes the pore structure of the sludge biochar. Subsequent sol-gel precipitation and calcination crystallization using ferric nitrate, urea, and hexadecyltrimethylammonium bromide result in the deposition of abundant magnetic particles in the sludge biochar. This significantly enhances the adsorption capacity of the sludge biochar and provides efficient protection for active microorganisms, stimulating their continuous and efficient function.

[0029] This invention combines two functional microbial agents. When the two bacteria are mixed in equal proportions, they can promote each other. The active substances produced can effectively passivate various heavy metal elements in the soil, maximizing the adsorption and degradation of heavy metals. At the same time, sludge biochar loaded with abundant magnetic particles serves as a microbial carrier, which can adhere to soil particles for a longer period of time to fully passivate heavy metals in the soil. This improves the passivation ability and passivation effect of this invention, minimizing the content of available heavy metal ions in the soil, and allowing the conditioner to work continuously and stably.

[0030] In summary, the beneficial effects of this invention are as follows:

[0031] (1) This invention uses urban sludge as raw material to prepare sludge biochar. Through steps such as drying and pyrolysis modification, the physicochemical properties of sludge biochar are fully improved, and its adsorption capacity for heavy metal ions is enhanced.

[0032] (2) The present invention combines Coccus roseus and Corynebacterium tumefaciens as functional microbial agents. The two work synergistically to achieve effective fixation and degradation of common heavy metal elements in soil, and to transform heavy metals into stable forms to reduce migration and bioavailability.

[0033] (3) At the same time, urea, humic acid, peanut shells and other nutrients are added to provide certain nutrients for crops and promote crop growth. Humic acid can also supplement the organic matter of farmland soil, improve the soil aggregate structure, alleviate the compaction of the soil by lime, and improve the fertility of farmland soil.

[0034] (4) Adding polyacrylamide and chitosan can increase the water retention of the soil. On the other hand, polyacrylamide has the same negative charge as the soil surface and can combine with soil particles through cation bridges to increase soil aggregate structure and regulate soil structure. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0036] Example 1

[0037] A biochar microbial activated soil conditioner is prepared from the following raw materials in parts by weight: 40 parts modified sludge biochar, 10 parts peanut shells, 20 parts humic acid, 5 parts urea, 10 parts ammonium dihydrogen phosphate, 5 parts attapulgite, 1 part microbial inoculant, and 0.1 parts conditioner.

[0038] The modified sludge biochar is obtained through drying, pyrolysis, and carbonization modification.

[0039] The method for preparing the modified sludge biochar is as follows:

[0040] (1) Dry the municipal sludge at a temperature of 100-110℃ for 24 hours. After drying, crush the sludge into...

[0041] Solid sludge particles of 0.5-1mm;

[0042] (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:5, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 300°C at a rate of 5-6°C per minute, held at the temperature for 1 hour, and then raised to 500°C at a rate of 1-2°C per minute. After holding at the temperature for 5 hours, the temperature is naturally cooled to obtain sludge biochar.

[0043] (3) Disperse the sludge biochar obtained in step (2) in water at a solid-liquid ratio of 1 kg: 1 L, add 1 wt% ferric nitrate of sludge biochar, then add 3 wt% urea of ​​sludge biochar, keep at 60°C for 15 min, then add 1 wt% hexadecyltrimethylammonium bromide of sludge biochar, raise the temperature to 95-100°C and continue stirring until the solution becomes gel-like, transfer to a vacuum drying oven at 110-130°C for 5 h, and then calcine at 600°C for 3 h to obtain the final product modified sludge biochar.

[0044] The microbial agents are *Coprinus roseus* with accession number CGMCC1.15046 and *Crassula pumilum* with accession number CCTCC AF 96007.

[0045] Kocuria rosea, with accession number CGMCC1.15046, was purchased from the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0046] The *Chrysosporium* species used in this embodiment, with accession number CCTCC AF 96007, was purchased from the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0047] The preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium and centrifuged at 5000 r / min for 8-10 min. The supernatant is discarded to obtain the two bacterial cells. Then, they are prepared into bacterial suspensions with physiological saline with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried.

[0048] The LB medium consists of: 2g trypsin, 1g trypsin mother powder, 2g sodium chloride, pH 7.4, diluted with distilled water to 200mL, and sterilized at 121℃ for 20min.

[0049] The conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:1.

[0050] A method for preparing a biochar microbial activated soil conditioner includes the following preparation steps:

[0051] (1) Preparation of modified sludge biochar;

[0052] (2) Preparation of microbial inoculants;

[0053] (3) Mix the modified sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

[0054] The granulation method in step (3) is as follows: Adjust the disc angle to 50°-60°, first adjust the rotation speed to 5r / min, spray atomized water while rotating, stop spraying water when particles with a diameter of 0.5-1mm are produced, adjust the rotation speed to 40r / min, rotate quickly until the particles have a diameter of 1-3.5mm and then stop.

[0055] Example 2

[0056] A biochar microbial activated soil conditioner is prepared from the following raw materials in parts by weight: 50 parts modified sludge biochar, 12 parts peanut shells, 20 parts humic acid, 5 parts urea, 8 parts ammonium dihydrogen phosphate, 6 parts attapulgite, 2 parts microbial inoculant, and 0.2 parts conditioner.

[0057] The modified sludge biochar is obtained through drying, pyrolysis, and carbonization modification.

[0058] The method for preparing the modified sludge biochar is as follows:

[0059] (1) Dry the urban sludge at a temperature of 100-110℃ for 24 hours. After drying, break the sludge into solid sludge particles of 0.5-1mm.

[0060] (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:6, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 300-400℃ at a rate of 5-6℃ per minute, held at the temperature for 1 hour, and then raised to 500℃ at a rate of 1-2℃ per minute. After holding at the temperature for 5 hours, the temperature is naturally cooled to obtain sludge biochar.

[0061] (3) Disperse the sludge biochar obtained in step (2) in water at a solid-liquid ratio of 1 kg: 1 L, add 1 wt% ferric nitrate of sludge biochar, then add 5 wt% urea of ​​sludge biochar, keep at 60°C for 15 min, then add 2 wt% hexadecyltrimethylammonium bromide of sludge biochar, raise the temperature to 95-100°C and continue stirring until the solution becomes gel-like, transfer to a vacuum drying oven at 110-130°C for 5 h, and then calcine at 600°C for 3 h to obtain the final product modified sludge biochar.

[0062] The microbial agents are *Coprinus roseus* with accession number CGMCC1.15046 and *Crassula pumilum* with accession number CCTCC AF 96007.

[0063] Kocuria rosea, with accession number CGMCC1.15046, was purchased from the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0064] The *Chrysosporium* species used in this embodiment, with accession number CCTCC AF 96007, was purchased from the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0065] The preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium and centrifuged at 5000 r / min for 8-10 min. The supernatant is discarded to obtain the two bacterial cells. Then, they are prepared into bacterial suspensions with physiological saline with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried.

[0066] The LB medium consists of: 2g trypsin, 1g trypsin mother powder, 2g sodium chloride, pH 7.4, diluted with distilled water to 200mL, and sterilized at 121℃ for 20min.

[0067] The conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:1.

[0068] A method for preparing a biochar microbial activated soil conditioner includes the following preparation steps:

[0069] (1) Preparation of modified sludge biochar;

[0070] (2) Preparation of microbial inoculants;

[0071] (3) Mix the modified sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

[0072] The granulation method in step (3) is as follows: Adjust the disc angle to 50°-60°, first adjust the rotation speed to 8r / min, spray atomized water while rotating, stop spraying water when particles with a diameter of 0.5-1mm are produced, adjust the rotation speed to 50r / min, rotate quickly until the particles have a diameter of 1-3.5mm and then stop.

[0073] Example 3

[0074] A biochar microbial activated soil conditioner is prepared from the following raw materials in parts by weight: 60 parts modified sludge biochar, 16 parts peanut shells, 15 parts humic acid, 8 parts urea, 5 parts ammonium dihydrogen phosphate, 7 parts attapulgite, 3 parts microbial inoculant, and 0.3 parts conditioner.

[0075] The modified sludge biochar is obtained through drying, pyrolysis, and carbonization modification.

[0076] The method for preparing the modified sludge biochar is as follows:

[0077] (1) Dry the municipal sludge at a temperature of 100-110℃ for 30 hours. After drying, crush the sludge into...

[0078] Solid sludge particles of 0.5-1mm;

[0079] (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:10, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 400°C at a rate of 5-6°C per minute, held at the temperature for 1 hour, and then raised to 500°C at a rate of 1-2°C per minute. After holding at the temperature for 5 hours, the temperature is naturally cooled to obtain sludge biochar.

[0080] (3) Disperse the sludge biochar obtained in step (2) in water at a solid-liquid ratio of 1 kg: 1 L, add 3 wt% ferric nitrate of sludge biochar, then add 8 wt% urea of ​​sludge biochar, keep at 60°C for 15-20 min, then add 2 wt% hexadecyltrimethylammonium bromide of sludge biochar, raise the temperature to 95-100°C and continue stirring until the solution becomes gel-like, transfer to a vacuum drying oven at 110-130°C for 5 h, and then calcine at 600°C for 3 h to obtain the final product modified sludge biochar.

[0081] The microbial agents are *Coprinus roseus* with accession number CGMCC1.15046 and *Crassula pumilum* with accession number CCTCC AF 96007.

[0082] Kocuria rosea, with accession number CGMCC1.15046, was purchased from the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0083] The *Chrysosporium* species used in this embodiment, with accession number CCTCC AF 96007, was purchased from the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0084] The preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium and centrifuged at 5000 r / min for 8-10 min. The supernatant is discarded to obtain the two bacterial cells. Then, they are prepared into bacterial suspensions with physiological saline with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried.

[0085] The LB medium consists of: 2g trypsin, 1g trypsin mother powder, 2g sodium chloride, pH 7.4, diluted with distilled water to 200mL, and sterilized at 121℃ for 20min.

[0086] The conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:1.

[0087] A method for preparing a biochar microbial activated soil conditioner includes the following preparation steps:

[0088] (1) Preparation of modified sludge biochar;

[0089] (2) Preparation of microbial inoculants;

[0090] (3) Mix the modified sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

[0091] The granulation method in step (3) is as follows: Adjust the disc angle to 50°-60°, first adjust the rotation speed to 10r / min, spray atomized water while rotating, stop spraying water when particles with a diameter of 0.5-1mm are produced, adjust the rotation speed to 60r / min, rotate quickly until the particles have a diameter of 1-3.5mm and then stop.

[0092] Example 4

[0093] A biochar microbial activated soil conditioner is prepared from the following raw materials in parts by weight: 80 parts modified sludge biochar, 20 parts peanut shells, 10 parts humic acid, 10 parts urea, 5 parts ammonium dihydrogen phosphate, 10 parts attapulgite, 4 parts microbial inoculant, and 0.5 parts conditioner.

[0094] The modified sludge biochar is obtained through drying, pyrolysis, and carbonization modification.

[0095] The method for preparing the modified sludge biochar is as follows:

[0096] (1) Dry the municipal sludge at a temperature of 100-110℃ for 30 hours. After drying, crush the sludge into...

[0097] Solid sludge particles of 0.5-1mm;

[0098] (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:10, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 400°C at a rate of 5-6°C per minute, held at the temperature for 1 hour, and then raised to 500°C at a rate of 1-2°C per minute. After holding at the temperature for 5 hours, the temperature is naturally cooled to obtain sludge biochar.

[0099] (3) Disperse the sludge biochar obtained in step (2) in water at a solid-liquid ratio of 1 kg: 1 L, add 3 wt% ferric nitrate of sludge biochar, then add 8 wt% urea of ​​sludge biochar, keep at 60°C for 15-20 min, then add 3 wt% hexadecyltrimethylammonium bromide of sludge biochar, raise the temperature to 95-100°C and continue stirring until the solution becomes gel-like, transfer to a vacuum drying oven at 110-130°C for 5 h, and then calcine at 600°C for 3 h to obtain the final product modified sludge biochar.

[0100] The microbial agents are *Coprinus roseus* with accession number CGMCC1.15046 and *Crassula pumilum* with accession number CCTCC AF 96007.

[0101] Kocuria rosea, with accession number CGMCC1.15046, was purchased from the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0102] The *Chrysosporium* species used in this embodiment, with accession number CCTCC AF 96007, was purchased from the China Center for Type Culture Collection, located at No. 299, Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0103] The preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium and centrifuged at 5000 r / min for 8-10 min. The supernatant is discarded to obtain the two bacterial cells. Then, they are prepared into bacterial suspensions with physiological saline with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried.

[0104] The LB medium consists of: 2g trypsin, 1g trypsin mother powder, 2g sodium chloride, pH 7.4, diluted with distilled water to 200mL, and sterilized at 121℃ for 20min.

[0105] The conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:1.

[0106] A method for preparing a biochar microbial activated soil conditioner includes the following preparation steps:

[0107] (1) Preparation of modified sludge biochar;

[0108] (2) Preparation of microbial inoculants;

[0109] (3) Mix the modified sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

[0110] The granulation method in step (3) is as follows: Adjust the disc angle to 50°-60°, first adjust the rotation speed to 5-10 r / min, spray atomized water while rotating, stop spraying water when particles with a diameter of 0.5-1 mm are produced, adjust the rotation speed to 40-60 r / min, rotate quickly until the particles have a diameter of 1-3.5 mm, then stop.

[0111] Comparative Example 1

[0112] A biochar microbial activated soil conditioner is prepared from the following raw materials in parts by weight: 80 parts sludge biochar, 20 parts peanut shells, 10 parts humic acid, 10 parts urea, 5 parts ammonium dihydrogen phosphate, 10 parts attapulgite, 4 parts microbial inoculant, and 0.5 parts conditioner.

[0113] The sludge biochar is obtained through drying and pyrolysis carbonization.

[0114] The method for preparing the sludge biochar is as follows:

[0115] (1) Dry the municipal sludge at a temperature of 100-110℃ for 30 hours. After drying, crush the sludge into...

[0116] Solid sludge particles of 0.5-1mm;

[0117] (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:10, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 400°C at a rate of 5-6°C per minute and held at a constant temperature for 1 hour. Then, the temperature is raised to 500°C at a rate of 1-2°C per minute and held at a constant temperature for 5 hours. After that, the temperature is naturally cooled to obtain sludge biochar.

[0118] The microbial agents are *Coprinus roseus* with accession number CGMCC1.15046 and *Crassula pumilum* with accession number CCTCC AF 96007.

[0119] This comparative example of Kocuria rosea, with accession number CGMCC1.15046, was purchased from the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0120] This comparative example, *Chrysosporium*, with accession number CCTCC AF 96007, was purchased from the China Center for Type Culture Collection, located at No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0121] The preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium and centrifuged at 5000 r / min for 8-10 min. The supernatant is discarded to obtain the two bacterial cells. Then, they are prepared into bacterial suspensions with physiological saline with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried.

[0122] The LB medium consists of: 2g trypsin, 1g trypsin mother powder, 2g sodium chloride, pH 7.4, diluted with distilled water to 200mL, and sterilized at 121℃ for 20min.

[0123] The conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:1.

[0124] A method for preparing a biochar microbial activated soil conditioner includes the following preparation steps:

[0125] (1) Preparation of sludge biochar;

[0126] (2) Preparation of microbial inoculants;

[0127] (3) Mix the sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

[0128] The granulation method in step (3) is as follows: Adjust the disc angle to 50°-60°, first adjust the rotation speed to 5-10 r / min, spray atomized water while rotating, stop spraying water when particles with a diameter of 0.5-1 mm are produced, adjust the rotation speed to 40-60 r / min, rotate quickly until the particles have a diameter of 1-3.5 mm, then stop.

[0129] In this comparative example, except for the absence of the third step of modification of sludge biochar, the raw materials and preparation methods are the same as in Example 4.

[0130] Comparative Example 2

[0131] The composition of the microbial inoculant was changed, while the remaining raw materials and preparation methods remained the same as in Example 4. Specifically, in the preparation method of the microbial inoculant:

[0132] The preparation method of the microbial agent is as follows: Coccus roseus and Leptotrichum thunbergii are activated separately, and after activation, they are inoculated into LB medium and centrifuged at 5000 r / min for 8-10 min. The supernatant is discarded to obtain the two bacterial cells. Then, they are prepared into bacterial suspensions with physiological saline with OD600≈1. Finally, the two bacterial suspensions are mixed at a volume ratio of 1:2, 2:1, 0:1 or 1:0 and spray-dried.

[0133] Table 1. Volume ratio of comparative bacterial suspensions

[0134] Comparative group Rose-colored Cochlea Phanerochaete chlamydophyllum Comparative Example 2 1 2 Comparative Example 3 2 1 Comparative Example 4 0 1 Comparative Example 5 1 0

[0135] Performance testing

[0136] Effect of strains on the removal of heavy metal ions

[0137] Preparation of activated bacterial cells: The bacterial suspensions of the microbial agents from Examples 4 and Comparative Examples 2-5 of this invention were inoculated into LB medium at a 2% inoculum and cultured on a shaker at 150 rpm for 12 hours. This liquid was used as activated bacterial cells for later use. The activated bacterial cells were added at 4% by volume to an LB solution containing known concentrations of heavy metals. After shaking at a constant temperature for 4 hours, a sample was taken, centrifuged at 8000 rpm for 10 minutes, and the concentration of remaining heavy metals in the supernatant was determined using a SpectrAA220 atomic absorption spectrophotometer. The removal rate was calculated.

[0138] The method for calculating the removal rate of heavy metals is as follows:

[0139]

[0140] Where R is the removal rate of heavy metals, C0 is the initial concentration of heavy metals (mg / L), and Ce is the concentration of heavy metals in the solution at equilibrium (mg / L).

[0141] The removal efficiency of each heavy metal particle is shown in Table 2:

[0142] Table 2 Experimental Results

[0143]

[0144] As shown in Table 2, the strains of this invention exhibit good removal effects on heavy metals lead, nickel, and copper. Furthermore, when the two strains are mixed in equal amounts, their removal of heavy metals is mutually promoted, particularly the removal of heavy metal ions. However, changing the ratio of the two strains disrupts this synergistic effect, weakening the removal effect on heavy metal ions.

[0145] Planting Trial

[0146] Heavy metal contaminated soil was retrieved from the contaminated site and planted in the Agricultural Experiment Park of the Linyi Academy of Agricultural Sciences in Shandong Province. Changes in soil properties before and after planting were statistically analyzed.

[0147] Test crop: Linmai No. 9

[0148] The soil type is alluvial brown soil, with a loam texture, moderate soil fertility, and 22.6 g·kg organic matter. -1 Hydrolyzable nitrogen 130.9 mg·kg -1 Available phosphorus 70.9 mg·kg -1 142.5 mg / kg of readily available potassium -1 The soil pH was 7.1. The content of toxic and harmful heavy metals was 0.015 mg / kg of available Hg. -1 The effective state of As is 1.201 mg·kg -1 Available Cd 0.033 mg·kg -1 Available Pb content: 4.56 mg·kg -1 The effective Cr content is 0.13 mg·kg. -1 .

[0149] The methods for soil sample analysis were as follows: pH value was determined according to NY / T 1121.2-2006; organic matter according to NY / T 1121.6-2006; hydrolyzable nitrogen according to Chapter 7, "Determination of Soil Nitrogen," of the "Technical Specification for Soil Analysis (Second Edition)"; available phosphorus according to NY / T1121.7-2014; available potassium according to NY / T 889-2004; available cadmium according to HJ 804-2016; available chromium according to HJ 166-2004; available lead according to HJ 804-2016; available arsenic according to DB35 / T 1459-2014; and available mercury according to DB35 / T 1459-2014. The methods for plant sample analysis were as follows: mercury and arsenic were determined by microwave digestion-atomic fluorescence spectrometry; and lead, cadmium, and chromium were determined by microwave digestion-graphite furnace atomic absorption spectrometry.

[0150] Ten treatment groups were set up, and the conditioners obtained in Examples 1-4 and Comparative Examples 1-5 were applied on the basis of conventional fertilization, with an application rate of 30 kg / mu. A blank control group was set up, which only performed conventional fertilization.

[0151] The planting results are shown in Table 3:

[0152] Table 3 Changes in soil properties before and after planting

[0153]

[0154] As can be seen from the data in Table 3, the conditioner of this invention can effectively reduce the content of various available heavy metal ions in the soil, with significant effects. However, the control level of heavy metals in soil was significantly reduced in Comparative Example 1, which lacked biochar modification, and Comparative Examples 2-5, which had altered microbial agent composition. This is because Comparative Example 1, which lacked biochar modification and used ordinary sludge biochar, had reduced activity and could not fully adsorb and protect the microbial agent. In Comparative Examples 2-5, which had altered agent composition, the balanced synergistic effect between strains disappeared, resulting in a decreased ability to degrade heavy metal ions in the soil, thus reducing the soil conditioning capacity.

[0155] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A biochar microbial activated soil conditioner, characterized in that, It is prepared from the following raw materials in parts by weight: 40-80 parts modified sludge biochar, 10-20 parts peanut shells, 10-20 parts humic acid, 5-10 parts urea, 5-10 parts ammonium dihydrogen phosphate, 5-10 parts attapulgite, 1-4 parts microbial inoculant, and 0.1-0.5 parts conditioner; the modified sludge biochar is obtained after drying, pyrolysis, and carbonization modification. The method for preparing the modified sludge biochar is as follows: (1) Dry the urban sludge at a temperature of 100-110℃ for 24-30 hours. After drying, break the sludge into solid sludge particles of 0.5-1mm. (2) Mix solid sludge particles with calcium sulfate at a mass ratio of 100:5-10, and then place them in a carbonization furnace for programmed temperature rise pyrolysis. Under a nitrogen atmosphere, the temperature is raised to 300-400℃ at a rate of 5-6℃ per minute, held at the temperature for 1 hour, and then raised to 500℃ at a rate of 1-2℃ per minute. After holding at the temperature for 5 hours, the temperature is naturally cooled to obtain sludge biochar. (3) Disperse the sludge biochar obtained in step (2) in water at a solid-liquid ratio of 1 kg: 1 L, add 1-3 wt% ferric nitrate of sludge biochar, then add 3-8 wt% urea of ​​sludge biochar, keep at 60°C for 15-20 min, then add 1-3 wt% hexadecyltrimethylammonium bromide of sludge biochar, raise the temperature to 95-100°C and continue stirring until the solution is gel-like, transfer to a vacuum drying oven at 110-130°C and dry for 5 h, then calcine at 600°C for 3 h to obtain the final product modified sludge biochar; The microbial inoculants are *Coprinus rosea* with accession number CGMCC1.15046 and *Clerodendrum thunbergii* with accession number CCTCCAF 96007. The preparation method of the microbial inoculants is as follows: *Coprinus rosea* and *Clerodendrum thunbergii* are activated separately, inoculated into LB medium, centrifuged at 5000 r / min for 8-10 min, the supernatant is discarded to obtain the two bacterial cells, and then the two bacterial suspensions are prepared separately with physiological saline to prepare bacterial suspensions with OD600≈1. Finally, the two bacterial suspensions are mixed in equal volumes and spray-dried. The conditioning agent is polyacrylamide and chitosan in a mass ratio of 1:

1.

2. A method for preparing the biochar microbial activated soil conditioner according to claim 1, characterized in that, The preparation steps include the following: (1) Preparation of modified sludge biochar; (2) Preparation of microbial inoculants; (3) Mix the modified sludge biochar and microbial agent thoroughly by weight, then add humic acid, urea, ammonium dihydrogen phosphate, attapulgite, conditioner and crushed peanut shells, mix and granulate with water or binder, and finally dry and shape.

3. The method for preparing the biochar microbial activated soil conditioner according to claim 2, characterized in that, Step (3) granulation method: Adjust the disc angle to 50°-60°, first adjust the rotation speed to 5-10r / min, spray atomized water while rotating, stop spraying water when particles with a diameter of 0.5-1mm are produced, adjust the rotation speed to 40-60r / min, rotate quickly until the particles have a diameter of 1-3.5mm and then stop.

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