Method for reducing emission of odor and greenhouse gases in compost

Abstract

The invention relates to a method for reducing emission of odor and greenhouse gases in compost, which comprises the following steps: S1, uniformly mixing compost raw materials to obtain a mixture A, and stacking the mixture A into a pile body; s2, the temperature of a pile body is made to reach 55 DEG C or above through pile body aeration or mechanical pile turning, and after the temperature is maintained for preset time T1, a mixture B is obtained; s3, carrying out secondary fermentation on the mixture B, and stopping the fermentation process when the temperature of the mixture B is close to the ambient temperature and is stably reduced or kept stable, so as to obtain a decomposed substance C; s4, newly building a compost body D, and covering the surface of the compost body D with the decomposed substance C according to the requirements on the raw material composition, the size and the shape of the compost body D and the mixture A to obtain a mixture E; s5, the mixture E is subjected to operation of the step S1 to the step S3, and the completely-decomposed organic fertilizer or the seedling raising and cultivation medium is obtained. The outer surface of the novel composting body is covered with the decomposed material, so that emission of odor and greenhouse gas in the composting process can be remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of composting, and in particular to a method for reducing odor and greenhouse gas emissions in composting. Background Art

[0002] With the development of social economy and the improvement of people's living standards, my country's livestock and poultry farming industry has developed rapidly, the breeding volume has increased rapidly, and the degree of intensive scale has been greatly improved. At present, the annual production of livestock and poultry manure in my country is about 3.8 billion tons, and the number of pigs killed and eliminated due to disease is about 60 million. The chemical oxygen demand emitted by the livestock and poultry farming industry alone reached 12.6826 million tons, accounting for 96% of the total agricultural source emissions, and the total nitrogen and total phosphorus emissions were 1.0248 million tons and 160,400 tons, becoming the main source of agricultural non-point source pollution; at the same time, livestock and poultry farming waste is also the main source of rural environmental pollution, seriously affecting the healthy development of the farming industry and the country's beautiful countryside creation plan. The unreasonable disposal of agricultural waste, especially untreated and improperly treated livestock and poultry manure and sewage, will bring many serious environmental problems.

[0003] Aerobic composting has become one of the most widely used ways to utilize aquaculture waste resources due to its advantages of on-site treatment, low cost, short time consumption, complete decomposition of organic matter, low product odor, high degree of harmlessness and low biological risk. Aerobic composting refers to the process of degrading carbon-containing organic matter in materials and generating high temperatures by using the biochemical action of microorganisms (bacteria, actinomycetes, yeasts, etc.) under artificial control conditions, controlling certain moisture, ventilation, C / N and other conditions, killing pathogens, insect eggs and weed seeds in agricultural waste, and converting them into organic fertilizer and cultivation substrate through fermentation and decomposition.

[0004] Aerobic composting will produce a large amount of odorous NH3 and H2S, greenhouse gases CH4, CO2 and N2O during the manure management process. Odorous NH3 and H2S are the main sources of environmental pollution.

[0005] In order to manage feces more effectively and reduce the harm caused by feces accumulation, composting technology has gradually developed in recent years. At present, the common composting technologies at home and abroad can be summarized into the following four categories, namely trough composting (the most widely used composting method at home and abroad, which mainly performs manual or mechanical turning operations on the basis of static composting on a regular basis), windrow composting (a typical open composting method, which piles the raw materials into narrow and long windrows, and the cross-section of the windrow is generally triangular or trapezoidal. The windrow is often large. This composting method does not have strict requirements for the oxygen supply of the windrow. It can be done without artificial disturbance like the static composting process, or it can be done by manual or mechanical turning to supply oxygen to the windrow. The specific turning frequency can be determined by the windrow temperature and windrow size), reactor composting (placing the material in a partially or fully closed warehouse, and controlling the oxygen content, turning frequency, windrow temperature and humidity and other conditions in the composting process efficiently, accurately and in real time through computer programs, providing the best aerobic fermentation environment for the material, and ultimately realizing a new type of composting method that accelerates the biodegradation and organic conversion process of the material). At present, windrow composting and trough composting account for more than 90% of the market, while reactor composting accounts for less than 10%.

[0006] Nowadays, manure composting technology has become a widely used method for industrial and agricultural waste management. This is because composting can not only reduce the amount of manure discharged in intensive animal husbandry, but also obtain a stable, humus-rich organic fertilizer and cultivation medium.

[0007] At present, the effective methods for controlling the generation of NH3 and H2S, greenhouse gases CO2, CH4, and N2O in odor mainly include: (1) Raw material control, mainly by adding high-carbon materials such as straw, sawdust, peanut shells or other deodorizing materials as conditioners to reduce the initial C / N (1) Adjust the moisture content and porosity of the materials to the appropriate ratio to reduce the generation of odor during the composting process; (2) Control the process parameters, control the organic waste composting process, optimize the aeration parameters, keep the material fermentation process in an aerobic state, and reduce the generation of odorous gases; (3) Deodorant control, generally achieved by adding microbial agents or chemical deodorants into the compost body, mainly by using oxidation, reduction, neutralization, addition, condensation, ion exchange and other reactions to convert the generated malodorous substances into odorless substances, thereby reducing the generation of odor during the organic waste composting process; (4) Collect and treat them centrally. However, the odor suppression technology of adding chemical deodorants on the surface of the compost body for the organic waste composting process is often ineffective. The reason is that the chemical deodorants are consumed as the composting process progresses, resulting in a gradual decrease in the deodorization effect until the effect is completely eliminated. If too much chemical deodorant is added, it will also affect the normal progress of the composting and increase the deodorization cost. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems existing in the prior art and provide a method for reducing odor and greenhouse gas emissions in composting.

[0009] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions: A method for reducing odor and greenhouse gas emissions in composting, the method comprising the following steps: Step S1: uniformly mixing the compost raw materials to obtain a mixture A, and piling the mixture A into a pile; Step S2: Aeration or mechanical turning of the pile is performed to make the pile temperature reach above 55°C and maintain the temperature for a preset time T1 to obtain a mixture B; Step S3: performing secondary fermentation on the mixture B, and stopping the fermentation process when the temperature thereof approaches the ambient temperature and steadily decreases or remains stable, thereby obtaining a mature product C; Step S4: creating a new compost body D, with the same raw material composition, size and shape requirements as the mixture A, and covering the surface of the compost body D with the decomposed matter C to obtain the mixture E; Step S5: Perform the operations of steps S1 to S3 on the mixture E to obtain fully decomposed organic fertilizer or seedling and cultivation medium.

[0010] Furthermore, in step S1, the carbon-nitrogen ratio of the mixture A after the compost raw materials are mixed is 20:1-40:1, the moisture content is 45%-65%, the particle size is not greater than 5 cm, and the pH is 5.5-9.0.

[0011] Furthermore, in step S1, the composting raw materials include multiple types of livestock and poultry manure, crop straw, edible fungus residue, vegetable waste, wood chips, rice husks, and food processing industry waste.

[0012] Furthermore, in step S1, the pile of mixture A is in the shape of a strip pile, a trough or a reactor, with a length of more than 10 meters, a bottom width of 3 to 5 meters, a height of 2 to 3 meters, and a longitudinal section that is nearly triangular or trapezoidal.

[0013] Furthermore, when windrow composting is used, the maintenance time T1 is not less than 15 days; When trough composting is used, the maintenance time T1 shall not be less than 7 days; When reactor composting is used, the maintenance time T1 is not less than 5 days.

[0014] Furthermore, in step S2, when the temperature of the pile is higher than 65°C, the temperature is lowered by turning the pile, stirring, aerating or any one or more of the following methods.

[0015] Furthermore, in step S2, the compost turning cycle is once every 7-10 days, so that the oxygen concentration inside the compost body is preferably not less than 5%, and the aeration air volume is 0.05m 2 / min~0.2m 2 / min.

[0016] Furthermore, in step S2, the compost turning method includes: Windrow composting uses a turning machine; Trough composting uses a chain-type compost turning machine or aeration at the bottom of the compost body; Reactor composting uses bottom aeration.

[0017] Furthermore, in step S4, the covering method is to cover the outer surface of the new compost with the decomposed material with a thickness of 10-20 cm.

[0018] The beneficial effects of the present invention are: The present invention covers the decomposed materials on the outer surface of the new compost body, and such covering of the decomposed compost can significantly reduce the emission of odor and greenhouse gases during the composting process. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to embodiments.

[0020] A method for reducing odor and greenhouse gas emissions in composting, the method comprising the following steps: Step S1: uniformly mixing the compost raw materials to obtain a mixture A, and piling the mixture A into a pile; Step S2: Aeration or mechanical turning of the pile is performed to make the pile temperature reach above 55°C and maintain the temperature for a preset time T1 to obtain a mixture B; Step S3: performing secondary fermentation on the mixture B, and stopping the fermentation process when the temperature thereof approaches the ambient temperature and steadily decreases or remains stable, thereby obtaining a mature product C; Step S4: creating a new compost body D, with the same raw material composition, size and shape requirements as the mixture A, and covering the surface of the compost body D with the decomposed matter C to obtain the mixture E; Step S5: Perform the operations of steps S1 to S3 on the mixture E to obtain fully decomposed organic fertilizer or seedling and cultivation medium.

[0021] In the step S1, the carbon-nitrogen ratio of the mixture A after the compost raw materials are mixed is 20:1-40:1, the moisture content is 45%-65%, the particle size is not more than 5 cm, and the pH is 5.5-9.0.

[0022] In step S1, the composting raw materials include livestock and poultry manure, crop straw, edible fungus residue, vegetable waste, wood chips, rice husks, and food processing industry waste.

[0023] In step S1, the pile of mixture A is in the shape of a strip pile, a trough or a reactor, with a length of more than 10 meters, a bottom width of 3 to 5 meters, a height of 2 to 3 meters, and a longitudinal section that is nearly triangular or trapezoidal.

[0024] When windrow composting is used, the maintenance time T1 shall not be less than 15 days; When trough composting is used, the maintenance time T1 shall not be less than 7 days; When reactor composting is used, the maintenance time T1 is not less than 5 days.

[0025] In step S2, when the temperature of the pile is higher than 65°C, the temperature is lowered by turning the pile, stirring, aerating or any one or more of the following methods.

[0026] In step S2, the compost is turned once every 7-10 days, so that the oxygen concentration inside the compost is not less than 5%, and the aeration air volume is 0.05m 2 / min~0.2m 2 / min.

[0027] In step S2, the compost turning method includes: Windrow composting uses a turning machine; Trough composting uses a chain-type compost turning machine or aeration at the bottom of the compost body; Reactor composting uses bottom aeration.

[0028] In step S4, the covering method is to cover the outer surface of the new compost with the decomposed material to a thickness of 10-20 cm.

[0029] In specific implementation: (1) There was no significant difference in the physical and chemical properties of the composting process and products between the covered and uncovered treatments, and both treatments reached the maturity standard. The piles of different treatments experienced three stages: the heating period, the high temperature period, and the cooling period. The temperature of all treatments could be maintained above 50°C for more than 5 days, meeting the requirements for the compost temperature in GB7959-2012 "Sanitary Requirements for Harmless Treatment of Excrement", and reaching the harmless requirements. The germination index reached 93.92% and 89.85% respectively at 35 days of composting, both reaching more than 80%. From the perspective of safety, the composts of the two treatments were fully mature at 35 days.

[0030] (2) Differences in odor and greenhouse gas emissions between the two treatment methods NH3 is one of the main components of odor. The cumulative emission of NH3 is 0.02g / Kg in the covered treatment and 0.137g / Kg in the uncovered treatment. The covered treatment reduced emissions by 85.4%, which was significantly different from the uncovered treatment (p<0.05).

[0031] H2S is one of the main components of odor. The cumulative emission of H2S is 0.013 mg / Kg in the covered treatment and 0.024 mg / Kg in the uncovered treatment. The covered treatment reduced emissions by 53.68%, which was significantly different from the uncovered treatment (p<0.05).

[0032] The cumulative emission of CH4 was 3.057g / Kg in the covered treatment and 9.387g / Kg in the uncovered treatment. The covered treatment reduced emissions by 67.4%, which was significantly different from the uncovered treatment (p<0.05).

[0033] The cumulative emission of N2O was 0.109g / Kg in the covered treatment and 0.062g / Kg in the uncovered treatment. The covered treatment increased the emission by 75.8%, which was significantly different from the uncovered treatment (p<0.05).

[0034] The cumulative emissions of CO2 were 161.527 g / Kg in the covered treatment and 207.583 g / Kg in the uncovered treatment. The covered treatment reduced emissions by 22.2%, which was significantly different from the uncovered treatment (p<0.05).

[0035] (3) Conclusion: Covering mature compost can significantly reduce odor and greenhouse gas emissions during the composting process, with a greenhouse gas (CO2 equivalent) emission reduction rate of 41.5%, as shown in Table 1 below: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for reducing odor and greenhouse gas emissions in composting, characterized in that: The method comprises the following steps: Step S1: uniformly mixing the compost raw materials to obtain a mixture A, and piling the mixture A into a pile; Step S2: Aeration or mechanical turning of the pile is performed to make the pile temperature reach above 55°C and maintain the temperature for a preset time T1 to obtain a mixture B; Step S3: performing secondary fermentation on the mixture B, and stopping the fermentation process when the temperature thereof approaches the ambient temperature and steadily decreases or remains stable, thereby obtaining a mature product C; Step S4: creating a new compost body D, with the same raw material composition, size and shape requirements as the mixture A, and covering the surface of the compost body D with the decomposed matter C to obtain the mixture E; Step S5: Perform the operations of steps S1 to S3 on the mixture E to obtain fully decomposed organic fertilizer or seedling and cultivation medium.

2. The method for reducing odor and greenhouse gas emissions in composting according to claim 1, characterized in that: In the step S1, the carbon-nitrogen ratio of the mixture A after the compost raw materials are mixed is 20:1-40:1, the moisture content is 45%-65%, the particle size is not more than 5 cm, and the pH is 5.5-9.

0.

3. The method for reducing odor and greenhouse gas emissions in composting according to claim 2, characterized in that: In step S1, the composting raw materials include livestock and poultry manure, crop straw, edible fungus residue, vegetable waste, wood chips, rice husks, and food processing industry waste.

4. The method for reducing odor and greenhouse gas emissions in composting according to claim 3, characterized in that: In step S1, the pile of mixture A is in the shape of a strip pile, a trough or a reactor, with a length of more than 10 meters, a bottom width of 3 to 5 meters, a height of 2 to 3 meters, and a longitudinal section that is nearly triangular or trapezoidal.

5. The method for reducing odor and greenhouse gas emissions in composting according to claim 4, characterized in that: When windrow composting is used, the maintenance time T1 shall not be less than 15 days; When trough composting is used, the maintenance time T1 shall not be less than 7 days; When reactor composting is used, the maintenance time T1 is not less than 5 days.

6. The method for reducing odor and greenhouse gas emissions in composting according to claim 1, characterized in that: In step S2, when the temperature of the pile is higher than 65°C, the temperature is lowered by turning the pile, stirring, aerating or any one or more of the following methods.

7. The method for reducing odor and greenhouse gas emissions in composting according to claim 1, characterized in that: In step S2, the compost is turned once every 7-10 days, so that the oxygen concentration inside the pile is preferably not less than 5%, and the aeration air volume is 0.05m 2 / min~0.2m 2 / min.

8. The method for reducing odor and greenhouse gas emissions in composting according to claim 7, characterized in that: In step S2, the compost turning method includes: Windrow composting uses a turning machine; Trough composting uses a chain-type compost turning machine or aeration at the bottom of the compost body; Reactor composting uses bottom aeration.

9. The method for reducing odor and greenhouse gas emissions in composting according to claim 1, characterized in that: In step S4, the covering method is to cover the outer surface of the new compost with the decomposed material to a thickness of 10-20 cm.

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