Novel efficient static composting process

Abstract

The invention discloses a novel efficient static composting process, which relates to the technical field of solid waste treatment and resource utilization, and comprises the following steps: step (1), pre-conditioning raw materials: pre-conditioning composting raw materials, controlling the particle size of the conditioned product to be 5-20mm, and controlling the occupancy to be more than 90%; and (2) carrying out sectional full-open-circuit reinforced fermentation after pre-fermentation: carrying out conventional aerobic pre-fermentation on the pre-conditioned compost raw material, and then carrying out sectional full-open-circuit reinforced fermentation on the pre-fermented compost raw material to obtain a final matured compost product. The novel efficient static composting process disclosed by the invention can synchronously realize the goals of efficient composting, harmlessness, standard reaching, environmental protection, low consumption and simple operation on the premise of ensuring the organic solid waste recycling rate, is suitable for various application scenes such as small-scale farms, community garbage treatment points, agricultural product processing parks and the like, and has wide application prospects. And a feasible technical scheme is provided for resource utilization of the organic solid waste.

Description

Technical Field

[0001] This invention relates to the technical field of solid waste treatment and resource utilization, and in particular to a new high-efficiency static composting process. Background Technology

[0002] The harmless treatment and resource utilization of livestock manure, kitchen waste, and agricultural and forestry waste have become key requirements for ecological environmental protection and the development of a circular economy. Static composting, due to its low equipment investment and ease of operation, has become one of the mainstream technologies for organic solid waste treatment. However, existing static composting processes still have the following core problems: Firstly, the decomposition efficiency is low and the harmlessness effect is poor. Traditional static composting relies on natural microbial decomposition, which easily leads to problems such as a short high-temperature period (50-65℃ for less than 5 days) and incomplete degradation of easily decomposable organic matter (residual rate exceeding 30%), resulting in a composting cycle of 60-90 days. At the same time, the pathogen killing rate (such as E. coli) is less than 90%, and the weed seed germination rate exceeds 10%, which is difficult to meet the requirements of "pathogen killing rate ≥90% and seed germination index GI ≥80%" in the "Organic Fertilizer Standard" (NY / T525-2021). The finished compost has the risk of soil pollution.

[0003] Secondly, controlling the microenvironment of the compost pile is difficult. Static composting, without mandatory turning, easily leads to stratification, characterized by "compacted and waterlogged bottom and dry, hardened top," resulting in poor aeration and uneven oxygen distribution (internal oxygen concentration below 8%). This, in turn, triggers anaerobic fermentation, producing large amounts of malodorous gases such as hydrogen sulfide and volatile organic compounds (TVOC) (TVOC emissions reach 500 mg / m³). 3 The above-mentioned areas have leachate COD values ​​exceeding 10,000 mg / L, causing pollution to surrounding water bodies and the atmospheric environment. At the same time, the pile temperature is significantly affected by the environment, failing to reach 45℃ in winter and exceeding 70℃ in some areas in summer, further deteriorating the fermentation effect.

[0004] Third, there is an imbalance between efficiency and environmental protection in the process design. Existing static composting mostly adopts the process of "multiple turning and closed-loop recirculation", which not only has high labor costs (more than 20 yuan per ton of compost), but also the return of unqualified materials will damage the micro-ecology of the compost pile and reduce the quality of the finished product. Although some closed fermentation processes can reduce pollution, the equipment investment exceeds 500,000 yuan per set, and the operating energy consumption accounts for more than 30% of the total cost, which is difficult for small and medium-sized processing scenarios to afford. On the other hand, low-cost open-air static composting cannot meet environmental emission standards, forming a dilemma of "cost-environment".

[0005] Fourth, functional additives have poor compatibility with composting systems. Most commercially available microbial agents are single-species, and their survival rate is less than 30% in the complex composting environment (pH fluctuations of 6.0-9.0, sudden temperature changes), making it difficult to continuously exert a degradation effect. Traditional conditioners (such as simple straw and sawdust) can only play a single role of loosening or water retention, and cannot take into account both aeration and water retention. In addition, natural conditioners have weak adsorption properties and are difficult to alleviate odor emissions. Furthermore, the conditioner modification process often uses high-temperature roasting or chemical soaking, which has problems such as long reaction time (over 2 hours) and complex process.

[0006] To address the aforementioned issues, existing technologies mostly focus on optimizing single steps (such as improving the microbial agent or increasing the number of turnings), failing to form a synergistic systemic solution encompassing "pretreatment-fermentation-auxiliary materials." Therefore, developing a new static composting process that is simple in procedure, cost-controllable, can simultaneously achieve efficient composting and harmless treatment, and is adaptable to different organic solid waste raw materials is of significant practical importance for promoting the resource utilization of organic solid waste and reducing environmental pollution risks. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the prior art, the present invention is proposed.

[0009] To solve the above technical problems, the present invention provides the following technical solution: a new high-efficiency static composting process, including the following steps: Step (1), raw material preconditioning: preconditioning the composting raw materials, and controlling the particle size of the product after conditioning to be 5~20mm with a content of more than 90%; Step (2), segmented open-circuit enhanced fermentation after pre-fermentation: conventional aerobic pre-fermentation is carried out on the pre-conditioned compost raw materials, and then segmented open-circuit enhanced fermentation is carried out on the pre-fermented compost materials to obtain the final decomposed compost product.

[0010] As a preferred embodiment of the efficient static composting process described in this invention, the composting raw materials contain more than 50% easily decomposable organic matter, have a carbon-to-nitrogen ratio (C / N) controlled at 20-30:1, and have an initial pathogen content ≥10. 5 CFU / g, calculated as Escherichia coli.

[0011] As a preferred embodiment of the new high-efficiency static composting process described in this invention, the segmented open-circuit enhanced fermentation includes two stages of open-circuit fermentation. The unqualified materials from the enhanced fermentation of stage I and stage II are combined with the pre-fermentation residue as secondary resource utilization raw materials. The qualified materials from the enhanced fermentation of stage II are the final mature compost products, with a pathogen kill rate of ≥99% and an organic matter maturity of ≥80%.

[0012] As a preferred embodiment of the new high-efficiency static composting process described in this invention, the functional microbial agent used in the enhanced fermentation is a compound microbial group combination agent, and the mass component ratio of the compound microbial group combination agent is: 30~50% thermophilic actinomycetes, 25~40% Bacillus, and 15~30% yeast.

[0013] As a preferred embodiment of the new high-efficiency static composting process described in this invention, the dosage of the compound microbial agent is 5-10 kg / t in the first stage of enhanced fermentation and 2-5 kg / t in the second stage of enhanced fermentation.

[0014] As a preferred embodiment of the new high-efficiency static composting process described in this invention, the conditioner used in the enhanced fermentation is a modified biomass conditioner, and its mass composition ratio is: 60~80% corn cob powder, 15~25% humic acid, and 5~10% bentonite.

[0015] As a preferred embodiment of the new high-efficiency static composting process described in this invention, the modified biomass conditioner is processed by wet heat treatment, with a wet heat treatment temperature of 120~160℃ and a wet heat treatment time of 30~90min.

[0016] As a preferred embodiment of the new high-efficiency static composting process described in this invention, the modified biomass conditioner is used at a rate of 50-80 kg / t in the first stage of enhanced fermentation and at a rate of 30-50 kg / t in the second stage of enhanced fermentation.

[0017] The beneficial effects of this invention are: 1. Achieving dual standards of decomposition and harmlessness: The pre-conditioning of raw materials controls the particle size to 5-20mm with a content of over 90%, ensuring full contact between microorganisms and materials, laying the foundation for efficient degradation; the combined microbial agent (thermophilic actinomycetes + Bacillus + yeast) works synergistically to significantly extend the high-temperature period (maintaining 50-65℃ for over 10 days), increasing the degradation rate of easily decomposed organic matter to over 90%, and the final compost product has a pathogen kill rate of ≥99% and a seed germination index (GI) of ≥82%, fully meeting the standards for harmlessness and decomposition of organic fertilizers, solving the core pain points of traditional composting: "incomplete decomposition and failure to meet harmlessness standards".

[0018] 2. Optimize the microenvironment of the compost pile and improve its environmental friendliness: After wet heat modification, the modified biomass conditioner (corn cob powder + humic acid + bentonite) forms a porous structure, which can ensure the aeration of the compost pile (oxygen concentration is stable at 10-15%) and lock in moisture (moisture content of the compost pile is maintained at 55-60%), effectively avoiding anaerobic fermentation. At the same time, the active groups on the surface of the conditioner can adsorb malodorous substances such as ammonia nitrogen and hydrogen sulfide, reducing TVOC emissions by more than 60% and the COD value of leachate to below 5000mg / L, solving the problem of "microenvironmental imbalance and serious secondary pollution" in static composting.

[0019] 3. Simplified process and reduced costs: The "two-stage open-circuit enhanced fermentation" process eliminates the need for multiple turnings and material recirculation, avoiding the deterioration of the fermentation environment by unqualified materials. The process steps are reduced by more than 40%, and the labor cost per ton of compost is reduced to less than 10 yuan. The gradient design of the dosage of compound microbial agents and modified conditioners (sufficient enhancement in stage I and precise supplementation in stage II) reduces the amount of agents used by 30% compared to the traditional process. Moreover, the wet heat modification (120-160℃, 30-90min) shortens the reaction time by more than 60% compared to the traditional modification process, significantly reducing energy consumption and auxiliary material costs, and solving the pain points of "complex process and high cost" in the traditional process.

[0020] 4. Improved compatibility of auxiliary materials and process stability: The compound microbial agent combines the high-temperature degradation ability of thermophilic bacteria, the stress resistance of Bacillus, and the organic matter conversion efficiency of yeast. The survival rate remains above 80% within the pH range of 6.0-9.0 and the temperature range of 30-70℃, making it suitable for different types of organic solid waste raw materials. The modified biomass conditioner achieves multi-functional synergy of "aeration-water retention-deodorization", overcoming the shortcomings of traditional conditioners with single functions. At the same time, four examples verified the compatibility of the process with different raw materials (livestock farm waste, kitchen waste, agricultural and forestry waste) and different parameter combinations. The final product quality is stable, solving the problems of "poor synergy of auxiliary materials and insufficient process stability".

[0021] In summary, the new high-efficiency static composting process of the present invention can simultaneously achieve the goals of "high-efficiency composting, harmless treatment, environmental protection and low consumption, and simple operation" while ensuring the resource utilization rate of organic solid waste. It is suitable for various application scenarios such as small-scale farms, community garbage disposal points, and agricultural product processing parks, and provides a practical and feasible technical solution for the resource utilization of organic solid waste. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the overall process of a new high-efficiency static composting process proposed in this invention. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Example 1 Reference Figure 1 A new, highly efficient static composting process includes the following steps: The compost material was taken from mixed waste (manure + straw) from a large-scale livestock farm in Chengde, Hebei Province. The compost contained 50% easily decomposable organic matter, a carbon-to-nitrogen ratio (C / N) of 20:1, and an initial pathogen (E. coli) content of 1.0 × 10⁻⁶. 5 CFU / g.

[0027] Raw material pretreatment: The above compost raw materials are mechanically crushed and screened for pretreatment. After pretreatment, the particle size of the product is controlled at 5~20mm, with a content of 90%. Pre-fermentation followed by segmented open-circuit intensive fermentation: The pre-conditioned compost raw materials undergo conventional aerobic pre-fermentation, and then the pre-fermented compost materials undergo segmented open-circuit intensive fermentation to obtain the final mature compost product.

[0028] Among them, the above-mentioned segmented open-circuit enhanced fermentation can meet the requirements with two open-circuit fermentation stages. The unqualified materials from the enhanced fermentation stages I and II can be combined with the pre-fermentation residue as secondary resource raw materials (used to prepare biomass briquette fuel), and the qualified materials from the enhanced fermentation stage II are the final compost products.

[0029] In the first stage of enhanced fermentation, the dosage of compound microbial agent is 5 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 50 kg / t (based on the dry weight of compost raw materials); in the second stage of enhanced fermentation, the dosage of compound microbial agent is 2 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 30 kg / t (based on the dry weight of compost raw materials).

[0030] The composition ratio of the compound microbial agent is as follows: 30% thermophilic actinomycetes, 40% Bacillus, and 30% yeast; the composition ratio of the modified biomass conditioner is as follows: 60% corn cob powder, 25% humic acid, and 10% bentonite; during the modification process of the modified biomass conditioner, the wet heat treatment temperature is 160℃ and the wet heat treatment time is 30min.

[0031] The pathogen (Escherichia coli) kill rate in the final compost product was 99.2%, and the organic matter maturity (seed germination index GI) was 82%.

[0032] Example 2 The compost raw materials were taken from a centralized kitchen waste treatment point in a community in Kunming, Yunnan (kitchen waste + garden leaves), with a content of 55% easily decomposable organic matter, a carbon-to-nitrogen ratio (C / N) of 25:1, and an initial pathogen content (E. coli) of 5.0 × 10⁻⁶. 5 CFU / g.

[0033] Raw material pretreatment: The above compost raw materials are mechanically crushed and screened for pretreatment. After pretreatment, the particle size of the product is controlled at 5~20mm, with a content of 92%. Pre-fermentation followed by segmented open-circuit intensive fermentation: The pre-conditioned compost raw materials undergo conventional aerobic pre-fermentation, and then the pre-fermented compost materials undergo segmented open-circuit intensive fermentation to obtain the final mature compost product.

[0034] Among them, the segmented open-circuit enhanced fermentation can meet the requirements with two open-circuit fermentation stages. The unqualified materials from the enhanced fermentation stages I and II can be combined with the pre-fermentation residue as secondary resource raw materials (used to prepare biomass briquette fuel), and the qualified materials from the enhanced fermentation stage II are the final compost products.

[0035] In the first stage of enhanced fermentation, the dosage of compound microbial agent is 7 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 60 kg / t (based on the dry weight of compost raw materials); in the second stage of enhanced fermentation, the dosage of compound microbial agent is 3 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 40 kg / t (based on the dry weight of compost raw materials).

[0036] The composition ratio of the compound microbial agent is: 40% thermophilic actinomycetes, 35% Bacillus, and 25% yeast; the composition ratio of the modified biomass conditioner is: 70% corn cob powder, 20% humic acid, and 10% bentonite; during the modification process of the modified biomass conditioner, the wet heat treatment temperature is 140℃ and the wet heat treatment time is 60min.

[0037] The pathogen (Escherichia coli) kill rate in the final compost product was 99.4%, and the organic matter maturity (seed germination index GI) was 85%.

[0038] Example 3 The compost raw materials were taken from waste (fruit and vegetable by-products + rice husks) from an agricultural product processing park in Chengdu, Sichuan. The content of easily decomposable organic matter was 60%, the carbon-to-nitrogen ratio (C / N) was 28:1, and the initial pathogen content (E. coli) was 8.0 × 10⁻⁶. 5 CFU / g.

[0039] Raw material pretreatment: The above compost raw materials are mechanically crushed and screened for pretreatment. After pretreatment, the particle size of the product is controlled at 5~20mm, with a content of 94%. Pre-fermentation followed by segmented open-circuit intensive fermentation: The pre-conditioned compost raw materials undergo conventional aerobic pre-fermentation, and then the pre-fermented compost materials undergo segmented open-circuit intensive fermentation to obtain the final mature compost product.

[0040] Among them, the segmented open-circuit enhanced fermentation can meet the requirements with two open-circuit fermentation stages. The unqualified materials from the enhanced fermentation stages I and II can be combined with the pre-fermentation residue as secondary resource raw materials (used to prepare biomass briquette fuel), and the qualified materials from the enhanced fermentation stage II are the final compost products.

[0041] In the first stage of enhanced fermentation, the dosage of compound microbial agent is 9 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 70 kg / t (based on the dry weight of compost raw materials); in the second stage of enhanced fermentation, the dosage of compound microbial agent is 4 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 45 kg / t (based on the dry weight of compost raw materials).

[0042] The composition ratio of the compound microbial agent is: 45% thermophilic actinomycetes, 30% Bacillus, and 25% yeast; the composition ratio of the modified biomass conditioner is: 75% corn cob powder, 18% humic acid, and 7% bentonite; during the modification process of the modified biomass conditioner, the wet heat treatment temperature is 130℃ and the wet heat treatment time is 70min.

[0043] The pathogen (E. coli) kill rate in the final compost product was 99.5%, and the organic matter maturity (seed germination index GI) was 88%.

[0044] Example 4 The compost material was sourced from waste (vegetable plant debris + peanut shells) from a large-scale planting base in Qingdao, Shandong Province. It contained 65% easily decomposable organic matter, a carbon-to-nitrogen ratio (C / N) of 30:1, and an initial pathogen (E. coli) content of 1.0 × 10⁻⁶. 6 CFU / g.

[0045] Raw material pretreatment: The above compost raw materials are mechanically crushed and screened for pretreatment. After pretreatment, the particle size of the product is controlled at 5~20mm with a content of 95%. Pre-fermentation followed by segmented open-circuit intensive fermentation: The pre-conditioned compost raw materials undergo conventional aerobic pre-fermentation, and then the pre-fermented compost materials undergo segmented open-circuit intensive fermentation to obtain the final mature compost product.

[0046] Among them, the above-mentioned segmented open-circuit enhanced fermentation can meet the requirements with two open-circuit fermentation stages. The unqualified materials from the enhanced fermentation stages I and II can be combined with the pre-fermentation residue as secondary resource raw materials (used to prepare biomass briquette fuel), and the qualified materials from the enhanced fermentation stage II are the final compost products.

[0047] In the first stage of enhanced fermentation, the dosage of compound microbial agent is 10 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 80 kg / t (based on the dry weight of compost raw materials); in the second stage of enhanced fermentation, the dosage of compound microbial agent is 5 kg / t (based on the dry weight of compost raw materials), and the dosage of modified biomass conditioner is 50 kg / t (based on the dry weight of compost raw materials).

[0048] The composition ratio of the compound microbial agent is: 50% thermophilic actinomycetes, 25% Bacillus, and 25% yeast; the composition ratio of the modified biomass conditioner is: 80% corn cob powder, 15% humic acid, and 5% bentonite; during the modification process of the modified biomass conditioner, the wet heat treatment temperature is 120℃ and the wet heat treatment time is 90min.

[0049] The pathogen (E. coli) kill rate in the final compost product was 99.6%, and the organic matter maturity (seed germination index GI) was 90%.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A new process of efficient static composting, characterized by, The method comprises the following steps: Step (1), raw material pre-conditioning: pre-conditioning the compost raw material, and controlling the particle size of the product after conditioning to be 5-20 mm, with a percentage of 90% or more; Step (2), pre-fermentation and segmented full-open circuit intensified fermentation: pre-fermenting the pre-conditioned compost raw material in a conventional aerobic manner, and then performing segmented full-open circuit intensified fermentation on the pre-fermented compost material, so as to obtain a final compost product.

2. A new process for efficient static composting according to claim 1, characterized in that: The content of perishable organic matter in the compost raw material is more than 50%, the carbon-nitrogen ratio (C / N) is controlled to be 20-30:1, and the initial pathogenic bacteria content is ≥10 5 CFU / g, measured in terms of Escherichia coli.

3. The new process for efficient static composting according to claim 1, characterized in that: The segmented full-open circuit intensified fermentation comprises two-stage open circuit fermentation, the unqualified material from the first-stage and second-stage intensified fermentation is combined with the pre-fermentation residue to serve as secondary resourceized raw material, and the qualified material from the second-stage intensified fermentation is the final compost product, with a pathogenic bacteria killing rate of 99% and an organic matter maturity of 80%.

4. The new process for efficient static composting according to claim 3, characterized in that: The functional bacterial agent used in the intensified fermentation is a composite bacterial group combined bacterial agent, and the mass component allocation ratio of the composite bacterial group combined bacterial agent is: 30-50% actinomycetes, 25-40% bacillus, and 15-30% yeast.

5. A new process for efficient static composting according to claim 4, characterized in that: The dosage of the composite bacterial group combined bacterial agent in the first-stage intensified fermentation is 5-10 kg / t, and the dosage in the second-stage intensified fermentation is 2-5 kg / t.

6. The new process for efficient static composting according to claim 3, characterized in that: The conditioning agent used in the intensified fermentation is a modified biomass conditioning agent, and the mass component allocation ratio of the modified biomass conditioning agent is: 60-80% corn cob powder, 15-25% humic acid, and 5-10% bentonite.

7. A new process for efficient static composting according to claim 6, characterized by: The treatment mode in the modification process of the modified biomass conditioning agent is wet heat treatment, the wet heat treatment temperature is 120-160 DEG C, and the wet heat treatment time is 30-90 min.

8. A new process for efficient static composting according to claim 7, characterized by: The dosage of the modified biomass conditioning agent in the first-stage intensified fermentation is 50-80 kg / t, and the dosage in the second-stage intensified fermentation is 30-50 kg / t.

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