Innocent treatment method of solid waste

Abstract

The invention relates to a harmless treatment method for solid waste. The compound probiotic microbial agent comprises bacillus licheniformis, lactobacillus rimosii, lactobacillus plantarum, clostridium butyricum and saccharomycetes, the effective viable count is larger than or equal to 0.5 billion / mL, pig manure, corn straw and saw dust are mixed according to the mass ratio to obtain a compost raw material, the initial carbon-nitrogen ratio (C / N) is adjusted to be 25-35, the water content is adjusted to be 55-65%, and the compost raw material is fermented to obtain the compound probiotic microbial agent. And adding a composite probiotic inoculant accounting for 0.5-2.5% of the total mass into the compost raw material. Through probiotic combination and concentration optimization, the problems of decomposition and pollution of various ARGs are solved at the same time.

Description

Technical Field

[0001] The invention relates to a method for harmlessly treating solid waste, and belongs to the technical field of resource utilization in environmental protection. Background Art

[0002] Pig farms produce enormous amounts of pig manure, which is relatively difficult to handle. Much of this manure is discharged into the environment without proper treatment. Livestock and poultry manure is inherently rich in nutrients essential for plant growth, such as nitrogen, phosphorus, and potassium, and is therefore often recycled back into farmland as organic fertilizer. In recent years, with the advancement of science and technology, large-scale, intensive farming practices have been gradually adopted by various countries. However, fresh animal manure is rich in antibiotics, hormones, heavy metals (Zn, Cu), resistance genes, and various pathogens. Directly discharging this waste into the environment without proper pretreatment can easily cause secondary pollution.

[0003] In the field of biological treatment, although many current technologies can achieve harmless treatment of manure, they do not effectively inhibit the growth of antibiotic resistance genes (ARGs) during aerobic composting. Therefore, it would be beneficial to obtain highly efficient organic fertilizer through harmless treatment. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention aims to provide a method for harmless treatment of solid waste, wherein a composite probiotic agent is added to the solid waste, and the number of effective live bacteria in the probiotic agent is ≥500 million / mL.

[0005] Preferably, the solid waste is any one or more solid waste selected from pig manure, corn stalks and sawdust.

[0006] Preferably, pig manure, corn stalks and sawdust are mixed according to a mass ratio to obtain a compost raw material (specifically), and the initial carbon-nitrogen ratio (C / N) is adjusted to 25-35 and the moisture content is 55-65%.

[0007] Preferably, 0.5-2.5% of the total mass of a composite probiotic agent is added to the compost raw material, and the agent comprises Bacillus licheniformis, Lactobacillus limonene, Lactobacillus plantarum, Clostridium butyricum and yeast.

[0008] Preferably, the composite probiotic agent is activated with brown sugar before use.

[0009] Preferably, antibiotic resistance genes are removed from the compost raw materials.

[0010] Preferably, the antibiotics include tetracyclines and macrolides.

[0011] By the present application, adding 2.5% of the composite probiotic agent can prolong the thermophilic period of aerobic composting, effectively kill pathogens and weed seeds in the pile, significantly improve the seed germination index of composting, promote the composting maturity, and obviously inhibit the proliferation and spread of antibiotic resistance genes ARGs in the aerobic composting process. Therefore, the application of the composite probiotic agent can effectively improve the process of aerobic composting, which has a positive significance for the harmless and resource utilization of solid waste. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The effect of adding different proportions of the composite probiotic agent of the present application on the temperature change of aerobic composting is shown;

[0013] Figure 2 The effect of adding different proportions of the composite probiotic agent of the present application on the change of seed germination index in the process of aerobic composting is shown;

[0014] Figure 3 The effect of adding different proportions of the composite probiotic agent of the present application on the change of antibiotic resistance genes ARGs in the process of aerobic composting is shown.

[0015] Among them, CK: no addition of composite probiotic agent; MC1: addition of 0.5% composite probiotic agent; MC2: addition of 1.5% composite probiotic agent; MC3: addition of 2.5% composite probiotic agent DETAILED DESCRIPTION

[0016] The present application is specifically described by the following examples, it is necessary to point out here that the following examples cannot be understood as a limitation to the protection scope of the present application, if some non-essential improvements and adjustments are made to the present application by skilled persons in the field according to the above application content, it still belongs to the scope of the present application.

[0017] The present application first discloses a probiotic combination for removing ARGs, the probiotic combination includes Bacillus licheniformis, Lactobacillus rhamnosus, Lactobacillus plantarum, Clostridium butyricum, yeast, but is not limited to this, as long as some specific enzymes can be secreted to accelerate the biodegradation of organic matter, adjust the physicochemical properties of the pile, enrich the composition and abundance of beneficial microorganisms. Through the present application, the composting maturity and the composite effect of inhibiting four types of ARGs are simultaneously improved.

[0018] In the present application, the composite probiotic agent is composed of Bacillus licheniformis, Lactobacillus rhamnosus, Lactobacillus plantarum, Clostridium butyricum, yeast and the like, the effective viable count is ≥5 billion / mL, the form of the agent belongs to liquid probiotic agent, and a proper amount of brown sugar is added to the composite probiotic agent before use to activate it fully under normal temperature and humidity.

[0019] Example 1: Aerobic composting experiment

[0020] Pig manure, corn straw and sawdust were added to the compost reactor in a mass ratio, mixed to obtain compost raw materials, and the initial carbon-nitrogen ratio (C / N) was adjusted to 30, and the moisture content was 60%. A total mass of 2.5% of a composite probiotic agent (MC3 group) was added to the compost raw materials, the agent comprising Bacillus licheniformis, Lactobacillus rhamnosus, Lactobacillus plantarum, Clostridium butyricum and yeast, and the effective viable bacterial count was ≥5 billion / mL. The composite probiotic agent was activated with brown sugar before use. The compost reactor was a thickened foam box with a cover, with a length × width × height of 735mm × 525mm × 465mm, and timely turning was performed during the composting process to ensure sufficient oxygen in the pile.

[0021] Example 2:

[0022] Pig manure, corn straw and sawdust were added to the compost reactor in a mass ratio, mixed to obtain compost raw materials, and the initial carbon-nitrogen ratio (C / N) was adjusted to 30, and the moisture content was 60%. A total mass of 2.5% of a composite probiotic agent (MC3 group) was added to the compost raw materials, the agent comprising Bacillus licheniformis, Lactobacillus rhamnosus, Lactobacillus plantarum, Clostridium butyricum and yeast, and the effective viable bacterial count was ≥5 billion / mL. The composite probiotic agent was activated with brown sugar before use. The compost reactor was a thickened foam box with a cover, with a length × width × height of 735mm × 525mm × 465mm, and timely turning was performed during the composting process to ensure sufficient oxygen in the pile.

[0023] Example 3:

[0024] Pig manure, corn straw and sawdust were added to the compost reactor in a mass ratio, mixed to obtain compost raw materials, and the initial carbon-nitrogen ratio (C / N) was adjusted to 30, and the moisture content was 60%. A total mass of 2.5% of a composite probiotic agent (MC3 group) was added to the compost raw materials, the agent comprising Bacillus licheniformis, Lactobacillus rhamnosus, Lactobacillus plantarum, Clostridium butyricum and yeast, and the effective viable bacterial count was ≥5 billion / mL. The composite probiotic agent was activated with brown sugar before use. The compost reactor was a thickened foam box with a cover, with a length × width × height of 735mm × 525mm × 465mm, and timely turning was performed during the composting process to ensure sufficient oxygen in the pile.

[0025] Comparative Example 1:

[0026] Pig manure, corn stalks and sawdust are added to the compost reactor in a mass ratio, mixed to obtain compost raw materials, and the initial carbon-nitrogen ratio (C / N) is adjusted to 30 and the moisture content is 60%. No composite probiotic inoculum (CK group) is added to the compost raw materials. The inoculum includes Bacillus licheniformis, Lactobacillus limonene, Lactobacillus plantarum, Clostridium butyricum and yeast, and the effective viable count is ≥ 500 million / mL. The composite probiotic inoculum is activated with brown sugar before use. The compost reactor is a thickened foam box with a cover of 735mm × 525mm × 465mm in length × width × height. During the composting process, the compost is turned in time to ensure that there is sufficient oxygen in the pile.

[0027] In the present invention, Figure 1 The effect of adding different proportions of the composite probiotic agent of the present invention on the temperature change of aerobic composting is shown in the figure. In the figure, CK: no composite probiotic agent is added; MC1: 0.5% composite probiotic agent is added; MC2: 1.5% composite probiotic agent is added; MC3: 2.5% composite probiotic agent is added. Figure 1 As shown, compost temperature increased dramatically from the initial stage to the second day, reaching a peak of 67.0°C, 68.0°C, 68.6°C, and 68.0°C in the CK, MC1, MC2, and MC3 groups, respectively. High compost temperatures (>50°C) can effectively kill pathogens and weed seeds in the compost. Adding the new composite probiotic inoculant further prolonged the high-temperature period of the compost compared to the control group.

[0028] In the present invention, the seed germination index is the most direct indicator for testing the toxicity of compost products. Figure 2 The results show that adding different proportions of the composite probiotic agent of the present invention affects the change of seed germination index during aerobic composting. Figure 2As shown, the seed germination index of the initial compost is low, which indicates that the toxicity of the compost at this time is relatively high and it is not suitable for direct reuse in farmland production. As the composting continues, the seed germination index of the four treatments shows a significant increase, which means that the toxicity of the pile is further reduced. After the composting is completed, the GI values ​​of the CK, MC1, MC2, and MC3 treatments were 92.6%, 106.5%, 119.1%, and 122.3%, respectively, all of which have reached the compost maturity standards specified in NY525-2021 (seed germination index ≥ 70%). The addition of a new composite probiotic agent further improves the seed germination index of the compost product, which is beneficial to the composting. Among them, the preferred addition amount of the new composite probiotic agent is 2.5%. When the dosage is between 0.5% and 1.5%, the inhibitory effect on some ARGs is not significant or even rebounds, such as tetracyclines. When 2.5% of the compound probiotic inoculant (MC3 group) was added, the compost product's seed germination index (GI) reached 122.3%, far exceeding the national standard of 70% and a 32% improvement over the uninoculated control group (CK group). This data demonstrates that this technology can effectively reduce compost phytotoxicity, ensuring the safety of compost products in farmland applications, and directly addressing the problem of crop growth inhibition caused by insufficient composting in traditional compost.

[0029] In the present invention, Figure 3 The changes of antibiotic resistance genes ARGs in aerobic composting process were shown by adding different proportions of the composite probiotic agent of the present invention. Figure 3As shown, after composting, the removal rates of tetracycline resistance genes in the CK, MC1, MC2, and MC3 treatments were -1.79%, -21.62%, -20.42%, and 8.59%, respectively. The MC3 treatment reduced the abundance of tetracycline resistance genes, while the tetracycline resistance genes in the other three groups rebounded to varying degrees after composting. Compared to 30.32% in the CK treatment, the removal rates of aminoglycoside resistance genes in the MC1, MC2, and MC3 treatments were 21.91%, 12.43%, and 33.14%, respectively. The MC3 treatment was more effective in removing aminoglycoside resistance genes than the other three treatments. As for macrolide and fluoroquinolone resistance genes, all treatments showed a significant increase after composting. The growth rates of macrolide resistance genes in CK, MC1, MC2, and MC3 after composting were 34.07%, 43.03%, 40.70%, and 16.81%, respectively. The growth rates of fluoroquinolone resistance genes in CK, MC1, MC2, and MC3 after composting were 22.62%, 34.94%, 36.46%, and 19.72%, respectively. This indicates that the MC3 treatment, with the addition of 2.5% of the composite probiotic inoculant, significantly inhibited the rebound of macrolide and fluoroquinolone resistance genes. In summary, the addition of 2.5% of the composite probiotic inoculant significantly reduced the presence of antibiotic resistance genes (ARGs). This is because the addition of probiotics increased the proliferation of beneficial bacteria in the compost, thereby indirectly inhibiting the colonization of resistance gene-bearing probiotics.

[0030] The present invention demonstrates through examples that a 2.5% addition of a microbial agent can simultaneously improve maturity (seed germination index > 120%), inhibit tetracycline and aminoglycoside resistance genes (ARGs), and significantly suppress the rebound of macrolide / fluoroquinolone ARGs (reducing the growth rate by more than 50%). Compared to traditional composting agents that focus on maturity or removing a single ARG, the present invention addresses both maturity and multiple ARG contamination issues through a specific combination of bacterial species and optimized concentrations.

[0031] In the present invention, the preferred addition of 2.5% of the composite probiotic agent can extend the thermophilic period of aerobic composting, effectively kill pathogens and weed seeds in the compost, significantly increase the compost seed germination index, promote compost maturity, and significantly inhibit the proliferation and spread of antibiotic resistance genes (ARGs) during aerobic composting. Therefore, the use of this composite probiotic agent can effectively improve the progress of aerobic composting, which has positive significance for the harmless treatment and resource utilization of solid waste.

Claims

1. A method for harmless treatment of solid waste, characterized in that: Add a composite probiotic agent to the solid waste, with the effective live bacteria count ≥ 500 million / mL.

2. The method according to claim 1, wherein The solid waste is any one or more solid wastes selected from pig manure, corn stalks and sawdust.

3. The method according to claim 2, wherein: Pig manure, corn stalks and sawdust are mixed according to a mass ratio to obtain a compost raw material, and an initial carbon-nitrogen ratio (C / N) is adjusted to 25-35 and a moisture content to 55-65%.

4. The method according to any one of claims 1 to 3, wherein 0.5-2.5% of the total mass of a composite probiotic agent is added to the compost raw material, wherein the probiotic agent comprises Bacillus licheniformis, Lactobacillus limonene, Lactobacillus plantarum, Clostridium butyricum and yeast.

5. The method according to claim 4, wherein The composite probiotic agent is activated with brown sugar before use.

6. The method according to any one of claims 1 to 5, wherein The antibiotic resistance genes in the compost raw materials are removed.

7. The method according to claim 6, wherein: The antibiotics include tetracyclines and macrolides.

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