A method for removing resistance genes and promoting humification in enhanced aerobic composting

Abstract

The present invention provides a method for enhancing the removal of resistance genes and promoting humification in aerobic composting. The method comprises the following steps: mixing livestock and poultry manure with a composting auxiliary material, adjusting the moisture content to 55%-65%, and adding a MnFe2O4 additive to obtain a composting raw material; aerobically composting the material, turning the compost every 2-3 days during a temperature rise period and a high temperature period, and every 7 days during a temperature fall period and a mature period, with the aerobic composting time being 20-30 days. Compared with a conventional composting method, the relative abundances of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes in the mature compost obtained by the method are reduced by 60%-73%, 50%-57%, 20%-80%, and 45%-66%, respectively, and the humic acid (HA) content is increased by about 15%. Meanwhile, the method achieves efficient harmlessness and resource utilization of organic solid waste, and has the potential for large-scale production.

Description

Technical Field

[0001] The invention belongs to the field of solid waste treatment, and in particular relates to a method for removing resistance genes and promoting humification in enhanced aerobic composting. Background Art

[0002] The use and even abuse of antibiotics has accelerated the emergence of drug-resistant bacteria. Microbial resistance has become one of the most serious global public health challenges. The United Nations Environment Programme has listed antibiotic resistance genes (ARGs) as the first of six emerging environmental issues. Livestock and poultry farming is an important "source" of antibiotic resistance, and livestock and poultry manure is an important reservoir of ARGs. When it is applied to farmland soil as fertilizer, it will cause a significant increase in the types and number of ARGs in the soil. Studies have found that the abundance of 63 ARGs subtypes in soils treated with manure is 192 to 28,000 times higher than in control soils (Zhu YG, Johnson TA, Su JQ et al., Diverse and abundant antibiotic resistance genes in Chinese swine farms. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110(9): 3435-3440.). ARGs in soil can further enter crops through the soil-plant system, ultimately posing a potential threat to human health through the food chain. Therefore, effectively preventing the spread of ARGs in livestock and poultry manure in the environment has become a public safety need.

[0003] Aerobic composting is one of the most important ways to make livestock and poultry manure harmless, reduce its volume and recycle it as a resource. However, traditional aerobic composting processes have problems such as slow biotransformation, incomplete harmlessness, and low humification degree (low fertilizer efficiency of the product). Existing studies have shown that although antibiotics can be degraded during the composting process, the resistance genes induced by antibiotics cannot be effectively reduced after traditional aerobic composting (Su JQ, Wei B, Qu Y et al., Antibiotic resistome and its association with bacterial communities during sewage sludge composting. Environmental Science & Technology, 2015, 49 (12): 7356-7363.). The application of additives is the main technical strategy for enhancing composting. At present, composting additives mainly include material additives such as microbial agents and biochar. Chinese patent CN116948883A discloses a composite Bacillus biological agent to reduce sulfonamide resistance genes sul1, sul2 and integron gene intI1 in aerobic composting of pig manure. Chinese patent CN116730755A discloses a method for promoting the degradation of lignocellulose in lignocellulose organic waste compost by inoculating high-efficiency lignocellulose hydrolyzing bacteria, thereby improving the quality of the compost product. However, microbial agents usually have high requirements for composting conditions, and exogenous microorganisms often cannot compete with indigenous microorganisms, so the effect is often not obvious in actual production. Chinese patent CN107129374A discloses a method for using bamboo biochar to reduce the abundance of tetracycline resistance genes in organic fertilizers. The method involves high-temperature cracking of bamboo at 600°C into biochar, which is then added to the compost at 2.5% of the dry weight of the compost material. The abundance of three tetracycline resistance genes in the biochar-treated compost was significantly lower than that in the control group. Chinese patent CN115196616A discloses a method for reducing ARGs in manure by using magnesium salt-modified biochar material. The method comprises mixing rice husk biochar with a magnesium salt solution to prepare a magnesium salt-modified biochar material, and adding the material to the compost material at 2% of the weight of the manure. Overall, the absolute abundance of sulfonamide resistance genes (sul2, dfrA1, dfrA7), macrolide resistance genes (ermF, ermB) and MGEs integron gene (intI1) in the magnesium salt-modified biochar addition group was lower than that in the control group, while the absolute abundance of sul1, sul2, dfrA7 and ermF genes in the ordinary biochar treatment group was significantly higher than that in the control group. The document "Spectroscopic Characterization of Humus in Compost Added with Different Proportions of Corn Biochar" (Hou Zhibin, Xie Yiping, Cao Changchun, Xu Jintao. Science, Technology and Engineering, 2023, 23(26): 11459-11475.) discloses that adding 10% and 15% corn biochar to compost can increase the humus content of the product.It can be seen that the biochar materials in these reported schemes usually use a large amount (2%-20% of the dry weight of the material), which greatly increases the production cost and is not conducive to field promotion and application.

[0004] MnFe2O4 is a type of spinel ferrite catalyst. Its microstructure, including variable oxygen vacancies and easily excited energy bands in the lattice, leads to variable microinterface properties. Currently, there are no reports on the application of MnFe2O4 in aerobic composting to reduce resistance genes and enhance humification. Summary of the Invention

[0005] In order to solve the technical problems of incomplete harmlessness and low humification degree in existing aerobic composting methods, the present invention provides a method for utilizing MnFe2O4 to enhance the removal of resistance genes and promote humification in aerobic composting.

[0006] Specifically, the present invention is achieved through the following technical solutions:

[0007] 1) Raw material preparation:

[0008] The livestock and poultry manure and compost auxiliary materials are mixed, the moisture content is adjusted to 55%-65% (the moisture content is preferably 60%), the carbon-nitrogen ratio is 20-30 (the C / N is preferably 25), and the MnFe2O4 additive is added along with the water to obtain a compost raw material;

[0009] The livestock and poultry manure includes one or more of pig manure, chicken manure, sheep manure or cow manure;

[0010] The composting auxiliary material is one or more of wheat straw, corn straw, rice straw or sawdust, which are crushed to a length of less than 3 cm;

[0011] The fresh weight ratio of livestock and poultry manure and compost auxiliary materials is 3:1-6:1;

[0012] The added amount of the MnFe2O4 additive is 0.01%-0.5% of the dry weight of the initial compost material.

[0013] 2) Aerobic composting:

[0014] Conventional aerobic composting is carried out using the compost raw materials prepared as described above. The compost is turned over every 2-3 days during the temperature rise period and high temperature period, and every 7 days during the temperature drop period and maturity period. The high temperature period of the compost temperature (above 50°C) is not less than 5 days, and the aerobic composting time is 20-30 days, thereby achieving enhanced removal of resistance genes in the compost product and promoting humification; the compost product meets the organic fertilizer maturity standard (NY525-2021).

[0015] The aerobic composting method in this step is a conventional composting method in the art, such as the method disclosed in the literature (Sun HJ, Chen S, Zhu Net al., Hydrothermal carbonization aqueous phase promotes nutrient retention and humic substance formation during aerobic composting of chicken manure. Bioresource Technology, 2023, 385: 129418.).

[0016] Preferably, the additive MnFe2O4 used in the above technical solution is prepared by the following hydrothermal method: configure 0.1 mol L -1 Ferric chloride and 0.05 mol L -1 Mixed solution of manganese chloride, add 3 mol L -1 The suspension was then injected into a high-pressure reactor, which was then placed in a muffle furnace and heated to 250°C at a rate of 10°C / min for 12 hours. After the reaction was complete, the high-pressure reactor was cooled to room temperature, and the sample was removed and washed several times with deionized water and ethanol alternately until the pH of the washings no longer changed. Finally, the sample was dried in a vacuum drying oven at 60°C for 12-24 hours, ground, and passed through a 300-mesh sieve to obtain a dark brown powder, which was the MnFe2O4 additive.

[0017] In this application, the terms "antibiotic resistance gene" and "resistance gene" refer to resistance genes for sulfonamides, tetracyclines, macrolides, and aminoglycosides. The term "enhancing or promoting humification" refers to increasing the humic acid content and improving the fertilizer efficiency of compost products.

[0018] Compared with the existing aerobic composting method, the method of the present invention for removing resistance genes and promoting humification in enhanced aerobic composting has the following beneficial effects:

[0019] 1) The present invention has a significant effect on enhancing the removal of resistance genes and humification. At the end of the composting in the embodiment, the relative abundance of sulfonamide resistance genes in the compost product obtained by the method of the present invention is reduced by 60%-73% compared with the control (wherein the relative abundance of sul1 gene is reduced by 60%-73% compared with the control, and the relative abundance of sul2 gene is reduced by 24%-69% compared with the control); the relative abundance of tetracycline resistance genes is reduced by 50%-57% compared with the control (wherein the relative abundance of tetC gene is reduced by 60%-84% compared with the control, the relative abundance of tetG gene is reduced by 25%-41% compared with the control, the relative abundance of tetM gene is reduced by 42%-53% compared with the control, the relative abundance of tetO gene is reduced by 12%-88% compared with the control, and the relative abundance of tetW gene is reduced by 10%-20% compared with the control). The relative abundance of ermB genes decreased by 42%-64% compared with the control, and the relative abundance of tetX genes decreased by 70%-73% compared with the control); the relative abundance of macrolide resistance genes decreased by 20%-80% compared with the control (among which the relative abundance of ermB genes decreased by 26%-57%, the relative abundance of ermC genes decreased by 1.4%-65%, and the relative abundance of ermF genes decreased by 11%-99% compared with the control); the relative abundance of aminoglycoside resistance genes decreased by 45%-66% compared with the control (among which the relative abundance of aadA genes decreased by 46%-77%, and the relative abundance of aadD decreased by 14%-43% compared with the control); humic substance HS increased by 2%-14% compared with the control, and humic acid HA increased by 6%-15% compared with the control.

[0020] 2) The present invention is simple to operate, has low material costs, and is pollution-free. The MnFe2O4 structure is highly controllable, and its interfacial properties can be manipulated by adjusting the metal molar ratio, calcination temperature, and time. This allows for targeted adaptation to the polyphenol-Maillard reaction catalytic mechanism, while achieving efficient, harmless, and resourceful disposal of organic solid waste, making it suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Comparison of the relative abundance changes of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes in the 0.01% MnFe2O4 addition group and the control group during the composting process in Example 1 of the present invention;

[0022] Figure 2 Comparison of changes in humic substance HS and humic acid HA content in the 0.01% MnFe2O4 addition group and the control group during the composting process in Example 1 of the present invention;

[0023] Figure 3 Comparison of the relative abundance changes of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes in the 0.1% MnFe2O4 addition group and the control group during the composting process in Example 2 of the present invention;

[0024] Figure 4Comparison of changes in humic substance HS and humic acid HA content in the 0.1% MnFe2O4 addition group and the control group during the composting process in Example 2 of the present invention;

[0025] Figure 5 Comparison of the relative abundance changes of sulfonamide, tetracycline, macrolide, and aminoglycoside resistance genes in the 0.5% MnFe2O4 addition group and the control group during the composting process in Example 3 of the present invention;

[0026] Figure 6 Comparison of changes in humic substance HS and humic acid HA content in the 0.5% MnFe2O4 addition group and the control group during the composting process in Example 3 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0028] Preparation method of MnFe2O4 in the embodiment:

[0029] Prepare 0.1 mol L -1 Ferric chloride and 0.05 mol L -1 Mixed solution of manganese chloride, add 3 mol L -1 NaOH solution to a pH of 12. Then inject the above suspension into a high-pressure reactor, place the high-pressure reactor in a muffle furnace for reaction (heating to 250°C at a rate of 10°C / min, reaction time is 12h). After the reaction is completed, wait for the high-pressure reactor to cool to room temperature, take out the sample, wash it alternately with deionized water and ethanol several times until the pH of the washing liquid no longer changes, and finally dry it in a vacuum drying oven (temperature 60°C, time 12h) to obtain a dark brown powder. After taking it out and grinding it, pass it through a 300-mesh sieve for use;

[0030] Example 1

[0031] (1) Material Preparation and Mixing: In this example, the chicken manure raw material was fresh chicken manure (70% moisture content) from a chicken farm in Nanjing, and wheat straw was obtained from the Liuhe experimental field of the Jiangsu Academy of Agricultural Sciences (8% moisture content). The wheat straw was crushed to <3 cm. Fresh chicken manure and wheat straw were mixed in a ratio of 5:1, and water was added to adjust the moisture content to 60% and the C / N ratio to 25. MnFe2O4 at 0.01% of the dry weight of the initial compost material was added along with the water. The group with MnFe2O4 added was designated as the experimental group, and the group without the additive was designated as the control group.

[0032] (2) Aerobic composting: The compost material obtained in step (1) was subjected to conventional aerobic composting. This embodiment used a conventional method for composting, referring to the method disclosed in “Sun HJ, Chen S, Zhu N et al., Hydrothermal carbonizationaqueous phase promotes nutrient retention and humic substance formation during aerobic composting of chicken manure. Bioresource Technology, 2023, 385: 129418.” A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm was used for composting. The compost was turned over every 2-3 days during the heating period and the high temperature period, and every 7 days during the cooling period and the decomposition period. The aerobic composting time was 30 days (both the experimental group and the control group were heated to above 50°C on the first day of composting, maintained above 50°C for 11 days, and then underwent a cooling and decomposition period). After testing, the compost products of the experimental group and the control group met the organic fertilizer decomposition standard (NY525-2021).

[0033] The resistance genes and humification parameters of the two groups were tested during the composting process. Figure 1 and Figure 2 shown. Figure 1 In the figure, (a)-(d) are the detection results of the relative abundance of sulfonamides, tetracyclines, macrolides, and aminoglycosides, respectively.

[0034] Resistance gene determination method: High-throughput qPCR method, the relative abundance of the target gene was normalized by 16S rRNA gene copy number, referring to the method of the literature "Zhu N, Long YJ, Kan ZX et al., Reduction of mobile genetic elements determines the removal of antibiotic resistance genes during pigmanure composting after thermal pretreatment. Bioresource Technology, 2023, 387: 129672."

[0035] Depend on Figure 1As the aerobic composting process progressed, the relative abundance of resistance genes decreased. However, a high level of resistance genes remained in the control group after 30 days of aerobic composting. Adding 0.01% MnFe₂O₄ significantly promoted the degradation of resistance genes. By the end of composting, the relative abundance of sulfonamide resistance genes decreased by 60%, tetracycline resistance genes by 50%, macrolide resistance genes by 80%, and aminoglycoside resistance genes by 66%.

[0036] Figure 2 In the figure, (a) and (b) are the test results for humic substance HS and humic acid HA, respectively. HS and HA determination method: 2g of ground compost sample was added to 20mL of extract (0.1mol / LNaOH and 0.1mol / LNa4P2O7, volume ratio 1:1), shaken at room temperature for 2h, centrifuged at 4000rpm for 10min, the supernatant was extracted, and the residue was removed. The above process was repeated three times for the residue. The filtrate is the total humic substance HS. 2 / 3 of the HS was acidified with 6mol / L hydrochloric acid to a pH of 1.0-2.0, stirred thoroughly, and allowed to stand overnight at room temperature. Centrifuged at 4000rpm for 10min, the precipitate is humic acid HA, which was dissolved with 0.1mol / LKOH and the volume was fixed. HS and HA in the sample were determined using a TOC analyzer.

[0037] Depend on Figure 2 As the aerobic composting process progressed, the degree of humification gradually increased. At the end of the composting period in the control group, HS increased by 33% and HA increased by 89%. The addition of 0.01% MnFe2O4 significantly promoted the humification process. At the end of the composting period, HS increased by 14% and HA increased by 15% compared to the control group.

[0038] Example 2

[0039] (1) Material Preparation and Mixing: In this example, the chicken manure raw material was fresh chicken manure (moisture content 75%) from a chicken farm in Zhenjiang City, and wheat straw was taken from a straw farm in Lianyungang (moisture content 7%). The wheat straw was crushed to 1-3 cm. Fresh chicken manure and wheat straw were mixed in a ratio of 3:1, and water was added to adjust the moisture content to 55% and the C / N ratio to 30. MnFe2O4 was added at 0.1% of the dry weight of the initial compost material along with the water. The group with MnFe2O4 added was designated as the experimental group, and the group without the additive was designated as the control group.

[0040] (2) Aerobic composting: The compost material obtained in step (1) is subjected to conventional aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm is used for composting. The pile is turned over once every 2-3 days during the heating period and the high temperature period, and once every 7 days during the cooling period and the mature period. The aerobic composting time is 30 days (both the experimental group and the control group are heated to above 50°C on the first day of composting, maintained above 50°C for 10 days, and then undergo a cooling and mature period). After testing, the compost products of the experimental group and the control group all meet the organic fertilizer mature standard (NY525-2021).

[0041] The resistance genes and humification parameters of the two groups were tested during the composting process. Figure 3 and Figure 4 The detection method is the same as that in Example 1.

[0042] Figure 3 In the figure, (a)-(d) are the detection results of the relative abundance of sulfonamides, tetracyclines, macrolides, and aminoglycosides, respectively. Figure 3 As the aerobic composting process progressed, the relative abundance of resistance genes decreased. However, the control group still had a high level of resistance genes after 30 days of aerobic composting. The addition of 0.1% MnFe2O4 significantly promoted the degradation of resistance genes. By the end of composting, the relative abundance of sulfonamide resistance genes decreased by 71%, tetracycline resistance genes by 56%, macrolide resistance genes by 20%, and aminoglycoside resistance genes by 45%.

[0043] Figure 4 In the figure, (a) and (b) are the test results of humic substance HS and humic acid HA respectively. Figure 4 As the aerobic composting process progressed, the degree of humification gradually increased. At the end of the composting period in the control group, HS increased by 33% and HA increased by 91%. The addition of 0.1% MnFe2O4 significantly promoted the humification process. At the end of the composting period, HS increased by 12% and HA increased by 9% compared to the control group.

[0044] Example 3

[0045] (1) Material Preparation and Mixing: In this example, the chicken manure raw material was fresh chicken manure (moisture content 60%) from a chicken farm in Yancheng City, and wheat straw was taken from a straw farm in Yancheng City (moisture content 9%). The wheat straw was crushed to 1-3 cm. Fresh chicken manure and wheat straw were mixed in a ratio of 6:1, and water was added to adjust the moisture content to 65% and the C / N ratio to 20. MnFe2O4 was added along with the water at 0.5% of the dry weight of the initial compost material. The group with MnFe2O4 added was designated as the experimental group, and the group without the additive was designated as the control group.

[0046] (2) Aerobic composting: The compost material obtained in step (1) is subjected to normal aerobic composting (the steps are the same as in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm is used for composting. The pile is turned over once every 2-3 days during the heating period and the high temperature period, and once every 7 days during the cooling period and the mature period. The aerobic composting time is 30 days (both the experimental group and the control group are heated to above 50°C on the first day of composting, and maintained above 50°C for 8 days, and then undergo a cooling and mature period). After testing, the compost products of the experimental group and the control group all meet the organic fertilizer mature standard (NY525-2021).

[0047] The resistance genes and humification parameters of the two groups were tested during the composting process. Figure 5 and Figure 6 The detection method is the same as that in Example 1.

[0048] Figure 5 In the figure, (a)-(d) are the detection results of the relative abundance of sulfonamides, tetracyclines, macrolides, and aminoglycosides, respectively.

[0049] Depend on Figure 5 As the aerobic composting process progressed, the relative abundance of resistance genes decreased. However, a high level of resistance genes remained in the control group after 30 days of aerobic composting. The addition of 0.5% MnFe₂O₄ significantly promoted the degradation of resistance genes. By the end of composting, the relative abundance of sulfonamide resistance genes decreased by 73%, tetracycline resistance genes by 57%, macrolide resistance genes by 29%, and aminoglycoside resistance genes by 63% compared to the control.

[0050] Figure 6 In the figure, (a) and (b) are the test results of humic substance HS and humic acid HA respectively. Figure 6 As the aerobic composting process progressed, the degree of humification gradually increased. At the end of the composting period in the control group, HS increased by 34% and HA increased by 88%. The addition of 0.5% MnFe2O4 significantly promoted the humification process. At the end of the composting period, HS increased by 2% and HA increased by 6% compared to the control group.

[0051] Comparative Example 1

[0052] (1) Material preparation and mixing: In the comparative example, the chicken manure raw material was fresh chicken manure from a chicken farm in Nanjing (moisture content 70%, sourced from the same example 1), and the wheat straw was taken from the Liuhe experimental field of Jiangsu Academy of Agricultural Sciences (moisture content 8%, sourced from the same example 1). The wheat straw was crushed to <3 cm.

[0053] Fresh chicken manure and wheat straw were mixed in a ratio of 5:1, and appropriate amount of water was added to adjust the moisture content to 60% and the C / N ratio to 25. 0.01% MnO2 based on the dry weight of the initial compost material was added along with the water. The group with added MnO2 (McLean, China) was set as the experimental group, and the group without additives was set as the control group.

[0054] (2) Aerobic composting: The compost material obtained in step (1) is subjected to conventional aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm is used for composting. The compost is turned over once every 2-3 days during the heating period and the high temperature period, and once every 7 days during the cooling period and the mature period. The aerobic composting time is 30 days (both the experimental group and the control group are heated to above 50°C on the first day of composting, and maintained above 50°C for 11 days, and then undergo a cooling and mature period). After testing, the compost products of the experimental group and the control group all meet the organic fertilizer mature standard (NY525-2021).

[0055] The resistance genes and humification parameters of the two groups were tested during the composting process using the same method as in Example 1. The results were compared with those of the MnFe2O4 addition group in Example 1, and are shown in Table 1.

[0056] Table 1 Relative abundance of resistance genes in mature compost products of each treatment group

[0057]

[0058] As shown in Table 1, compared with the control, MnO2 addition increased the relative abundance of various resistance genes in the compost, while reducing the content of humic acid (HS) by 13% and showing a limited increase in humic acid (HA) by 4.7%. However, MnFe2O4 addition significantly promoted the degradation of resistance genes, with the relative abundance of sulfonamide resistance genes in the compost decreasing by 60%, tetracycline resistance genes by 50%, macrolide resistance genes by 80%, and aminoglycoside resistance genes by 66%. Furthermore, MnFe2O4 addition significantly promoted the humification of the compost, with humic acid (HS) increasing by 14% and humic acid (HA) by 15% compared with the control.

[0059] Comparative Example 2

[0060] (1) Material preparation and mixing: In this embodiment, the chicken manure raw material was taken from fresh chicken manure (moisture content 70%, the same source as in Example 1) from a chicken farm in Nanjing, and the wheat straw was taken from the Liuhe experimental field of Jiangsu Academy of Agricultural Sciences (moisture content 8%, the same source as in Example 1). The wheat straw was crushed to 1-3 cm.

[0061] Fresh chicken manure and wheat straw were mixed in a ratio of 5:1, and the carbon-nitrogen ratio was adjusted to 25. An appropriate amount of water was added to adjust the moisture content to 60%. 0.01% MnSO4 of the dry weight of the initial compost material was added along with the water. The group with added MnSO4 (McLean, China) was set as the experimental group, and the group without additives was set as the control group.

[0062] (2) Aerobic composting: The compost material obtained in step (1) is subjected to conventional aerobic composting (the steps are the same as those in Example 1). A cubic insulated box with a length of 63 cm, a width of 48 cm, and a height of 36 cm is used for composting. The compost is turned over once every 2-3 days during the heating period and the high temperature period, and once every 7 days during the cooling period and the mature period. The aerobic composting time is 30 days (both the experimental group and the control group are heated to above 50°C on the first day of composting, and maintained above 50°C for 11 days, and then undergo a cooling and mature period). After testing, the compost products of the experimental group and the control group all meet the organic fertilizer mature standard (NY525-2021).

[0063] The resistance genes and humification parameters of the two groups were tested during the composting process using the same method as in Example 1. The results were compared with those of the MnFe2O4 addition group in Example 1, and are shown in Table 2.

[0064] As shown in Table 2, compared with the control, the addition of MnSO₄ increased the relative abundance of various resistance genes in the compost. Meanwhile, the HS content of humic substances remained unchanged, while the HA content of humic acid increased slightly (by 7%). However, the addition of MnFe₂O₄ significantly promoted the degradation of resistance genes, with the relative abundance of sulfonamide resistance genes in the compost decreasing by 60%, tetracycline resistance genes by 50%, macrolide resistance genes by 80%, and aminoglycoside resistance genes by 66% compared with the control. Furthermore, the addition of MnFe₂O₄ significantly promoted the humification of the compost, with HS content in the compost increasing by 14% and HA content in the compost increasing by 15% compared with the control.

[0065] Table 2 Relative abundance of resistance genes in mature compost products of each treatment group

[0066]

[0067] Although the above embodiments have been used to fully describe the present invention through general explanations and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present invention. Therefore, such modifications or improvements, which do not depart from the spirit of the present invention, are intended to fall within the scope of protection claimed in the present invention.

Claims

1. A method for removing resistance genes and promoting humification in enhanced aerobic composting, characterized in that: The specific steps are as follows: After mixing livestock and poultry manure and compost auxiliary materials, adjusting the moisture content to 55%-65%, adding MnFe2O4 to obtain compost raw materials; The livestock and poultry manure includes one or more of pig manure, chicken manure, sheep manure or cow manure; The composting auxiliary material includes one or more of wheat straw, corn straw, rice straw or sawdust; Aerobic composting is performed using compost materials for 20-30 days to achieve the removal of resistance genes in the enhanced compost product and promote humification; The resistance gene includes at least one of sulfonamide resistance genes, tetracycline resistance genes, macrolide resistance genes, and aminoglycoside resistance genes.

2. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: In step 1), the mass ratio of livestock and poultry manure to compost auxiliary material is 3:1-6:

1.

3. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 1): The length of the composting auxiliary material is less than 3 cm.

4. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 1) The amount of MnFe2O4 added is 0.01%-0.5% of the dry weight of the compost raw material.

5. The method for enhancing the removal of resistance genes and promoting humification in aerobic composting according to claim 1, characterized in that: Step 2) The aerobic composting means that the compost is turned every 2-3 days during the temperature rise period and the high temperature period, and every 7 days during the temperature drop period and the mature period, and the compost temperature is higher than 50°C for no less than 5 days.

6. The method for removing resistance genes and promoting humification in enhanced aerobic composting according to any one of claims 1 to 5, characterized in that: Step 1) The MnFe2O4 is prepared by the following method: -1 Ferric chloride and 0.05 mol L -1 To the mixed solution of manganese chloride, 3 mol L -1 The pH was adjusted to 12 by NaOH; the mixture was then placed in a muffle furnace and heated to 250°C at a rate of 10°C / min, reacted for 12 h, and naturally cooled. The solid was washed with deionized water and ethanol, dried, ground, and passed through a 300-mesh sieve to obtain the MnFe2O4.

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