Method for promoting biogas residue aerobic composting humification process

Abstract

The invention provides a method for promoting a biogas residue aerobic composting humification process, and belongs to the technical field of solid waste recycling. The method comprises the following steps: crushing and sieving tea wastes, adding into water, fully stirring, and filtering to obtain a tea residue leachate; mixing the biogas residue with a high C / N auxiliary material according to a carbon-nitrogen ratio to obtain a compost raw material; adding the tea residue leachate into the compost raw material, then adjusting the moisture content, and then carrying out aerobic fermentation to obtain a compost product. According to the method, by promoting the humification process, the aerobic composting efficiency of the biogas residues is improved, the retention rate of organic matters in the composting process can be increased, and the loss of the total organic carbon content is reduced by 40-50%; the humification process can be effectively accelerated, the humic acid coefficient is increased by 10%-30%, and the polymerization degree is increased by 60%-80%; the aerobic composting efficiency is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for promoting the aerobic composting and humification process of biogas residue. Background Technology

[0002] With rapid urbanization and industrialization, the amount of solid waste is increasing rapidly. If this waste is not properly disposed of, it will cause enormous damage to the natural environment. However, if appropriate treatment methods are adopted, this waste can become a reliable resource, turning waste into treasure. Food waste has a high organic content, rich nutrients, good biodegradability, and significant resource potential. Anaerobic digestion is a commonly used method for treating food waste. This method can effectively reduce waste volume, and its digestate can be used as fertilizer to improve soil quality and can also produce biogas for renewable energy. However, the sludge produced by anaerobic digestion still contains many incompletely degraded organic matter, which has the potential for further resource utilization.

[0003] Composting is primarily used for food waste, agricultural waste, and yard waste, and is a reliable method for treating anaerobic digestion sludge. The composting process transforms waste into valuable humus, which can be used as agricultural fertilizer to support crop growth and reduce reliance on chemical fertilizers. The heat generated during the high-temperature composting process effectively kills pathogens in the sludge, improving product safety. Sludge typically emits a strong odor, but composting technology can deodorize it by degrading ammonia and volatile organic compounds, making the product more suitable for agricultural applications.

[0004] In the humification process of composting, humic precursors play a crucial role in building the basic framework of humic matter and are a significant factor influencing the humification efficiency. Humic precursors mainly include lignin, cellulose, polyphenols, and proteins. Among them, polyphenols can combine with amino acids and other substances through the phenolic hydroxyl groups (polyphenol-Maillard pathway), promoting the formation of complex macromolecular organic matter. Furthermore, polyphenols degrade relatively slowly, which is beneficial for producing more durable and stable humic matter. Catechol is a typical polyphenol and is often used in research to optimize the composting process. However, catechol has biotoxicity, inhibiting microbial activity in the early stages of composting, thus reducing composting efficiency, and also has environmental pollution effects, which can affect the safety and reliability of compost products. Tea polyphenols are natural polyphenols with strong antioxidant properties. They are abundant in agricultural and forestry wastes such as tea dregs, tea seed shells, and tea branches and leaves, and are characterized by their wide availability, non-toxicity, and non-polluting nature, making them potential for optimizing composting processes. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for promoting the aerobic composting and humification process of biogas residue. This invention composts biogas residue by using straw, sawdust, and mushroom residue as auxiliary materials to adjust the carbon-nitrogen ratio. During the composting process, tea residue leachate rich in natural plant polyphenols (tea polyphenols) is added to reduce carbon emissions through oxidation and polymerization, promote the aerobic composting and humification process, and thus improve the humus content and composting efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for promoting the aerobic composting and humification process of biogas residue, comprising the following steps: After crushing and sieving tea industry waste, it is added to water and stirred thoroughly. The mixture is then filtered to obtain a tea residue extract rich in natural polyphenols. The biogas residue and high C / N auxiliary materials are mixed according to the carbon-nitrogen ratio to obtain composting raw materials; Tea residue extract is added to the composting raw materials, the moisture content is adjusted, and then aerobic fermentation is carried out to obtain the compost product.

[0007] In a preferred embodiment of the present invention, the sieving is performed through a 10-mesh sieve.

[0008] In a preferred embodiment of the present invention, the tea waste is at least one of tea dregs, tea seed shells, and tea tree branches and leaves; the mass ratio of the tea waste to water is 1:8 to 1:12; and the stirring is performed by continuous stirring for 1 hour in a constant temperature water bath at 30 to 40°C.

[0009] In a preferred embodiment of the present invention, the biogas residue is the solid residue after anaerobic digestion of organic waste; the organic waste includes, but is not limited to, wet waste, feces, and sludge.

[0010] In a preferred embodiment of the present invention, the high C / N auxiliary material is a mixture of straw, sawdust, and mushroom residue in a mass ratio of (6~8):(1~2):(2~3); the particle size of the high C / N auxiliary material is 1~2 mm. Through the synergistic complementarity of the three materials, the carbon-nitrogen ratio of the pile is adjusted, the pore structure is improved to enhance aeration, and the moisture is balanced to create an ideal environment for microorganisms to efficiently degrade organic matter.

[0011] In a preferred embodiment of the present invention, the carbon-nitrogen ratio is 20:1 to 30:1.

[0012] In a preferred embodiment of the present invention, the moisture content is 50% to 70%. Moisture content refers to the percentage of water mass in the composting raw material to the total mass of the raw material.

[0013] In a preferred embodiment of the present invention, the amount of tea residue extract added is 8% to 12% of the wet basis mass of the composting raw materials. Excessive polyphenols will inhibit the microbial activity during the composting process, thereby delaying the biodegradation of organic matter and hindering the composting process.

[0014] In a preferred embodiment of the present invention, the aerobic fermentation time is 36 days, the aeration rate is 0.6~1.0L / min / kg, and the aeration frequency is 10min on / 20min off.

[0015] The composting reactor involved in this invention is constructed of two layers of plexiglass, and the exterior is wrapped with insulating cotton to prevent heat loss during composting. The main body of the reactor has a volume of approximately 10L, with an aeration chamber at the bottom that is 30mm high. The top of the composting reactor is covered and an exhaust pipe is inserted. Air is supplied via a flexible hose, and oxygen from an air pump enters the aeration chamber from the bottom of the reactor. The top of the aeration chamber is fitted with a 100-mesh metal mesh to prevent material leakage. The reactor is placed inside an insulated foam box with heat-insulating tape on the outside to further prevent heat loss.

[0016] The present invention discloses the following technical effects: (1) This invention provides a method to promote the aerobic composting humification process. By adding tea residue leachate, the organic matter conversion of compost is promoted, which is manifested by increased temperature and oxygen consumption, promoting the conversion of protein organic matter into humus, reducing the loss of total organic carbon content by 40% to 50%, and significantly improving carbon retention rate.

[0017] (2) Tea residue extract provides plant polyphenols that enhance the aroma of humic acid by rapidly consuming precursors and introducing lignin-derived monomers; it can also improve the diversity of humic acid functional groups through polysaccharides and aliphatic substances, thereby achieving a synergistic increase in humic acid yield and degree of polymerization. The humic acid coefficient increases by 10%~30%, and the degree of polymerization increases by 60%~80%; effectively accelerating the humification process.

[0018] (3) This method utilizes tea dregs and other tea industry waste to prepare compost additive leachate. Compared with mineral fertilizers and artificial synthetic additives, it can effectively avoid soil salinity imbalance, plant toxicity and microbial inhibition, and helps protect the soil ecosystem. This method is based on waste resource utilization, and is both economical and environmentally friendly, in line with the goals of green economy and sustainable development. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0025] The detection methods involved in the following embodiments are as follows: Dissolved organic carbon (DOC): Weigh the sample (1:10, wet weight) and mix it with water in a 250 ml Erlenmeyer flask. Place the flask in a constant temperature incubator (150 r / min, 24 h, 25 ℃). Take the supernatant and filter it through a 0.45 μm filter membrane to obtain dissolved organic matter (DOM). Use a total organic carbon analyzer to determine the DOC.

[0026] The humic content was analyzed using a sodium hydroxide-sodium pyrophosphate extraction method. Samples passing through a 100-mesh sieve were extracted with a sodium hydroxide-sodium pyrophosphate solution by shaking. The extract was centrifuged and filtered through a membrane to obtain the supernatant. A suitable amount of the supernatant was taken to determine the TOC, recorded as the humic acid content (HS-C). A certain volume of the supernatant was acidified with sulfuric acid for 24 hours, then centrifuged to obtain the supernatant, and its TOC was determined, recorded as the fulvic acid content (FA-C). The humic acid content (HA-C) was the difference between the humic acid content (HS-C) and the fulvic acid content (FA-C).

[0027] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0028] Example 1 A method for promoting the aerobic composting and humification process of biogas residue, the specific steps of which are as follows: (1) Tea waste such as tea dregs, tea seed shells, and tea tree branches and leaves are cut and crushed and passed through a 10-mesh sieve to obtain dregs; the dregs are mixed with ultrapure water at a mass ratio of 1:12 and stirred continuously for 1 hour in a constant temperature water bath at 30℃, and then filtered to obtain tea dregs extract.

[0029] (2) A high C / N ratio auxiliary material (a mixture of straw, sawdust, and mushroom residue in a mass ratio of 6:1:3) was mixed with kitchen waste biogas residue at a C / N ratio of 20:1 to obtain composting raw material. Then, tea residue leachate was added (8% of the wet basis mass of the composting raw material). The initial moisture content of the compost mixture was adjusted to 50%. After the composting materials were mixed evenly, they were transferred to the composting reactor. The composting cycle was 36 days, the aeration rate was 0.6 L / min, and the aeration frequency was 10 min on / 20 min off. During the composting period, the material was turned over with a shovel.

[0030] After composting, the total organic carbon (TOC) content decreased from 56% to 45%, with a TOC loss rate of 19%; the humification coefficient (HR) was 26%; the humic acid ratio (PHA) and degree of polymerization (DP) were 57% and 1.38, respectively. The high PHA and DP values ​​indicate that the tea residue extract effectively increased the molecular weight and structural complexity of HS.

[0031] Example 2 A method for promoting the aerobic composting and humification process of biogas residue, the specific steps of which are as follows: (1) Tea waste such as tea dregs, tea seed shells, and tea tree branches and leaves are cut and crushed and passed through a 10-mesh sieve to obtain dregs; the dregs are mixed with ultrapure water at a mass ratio of 1:12 and stirred continuously for 1 hour in a constant temperature water bath at 35℃, and then filtered to obtain tea dregs extract.

[0032] (2) A high C / N ratio auxiliary material (a mixture of straw, sawdust, and mushroom residue in a mass ratio of 6:1:3) was mixed with kitchen waste biogas residue at a C / N ratio of 25:1 to obtain composting raw material. Then, tea residue leachate was added (10% of the wet basis mass of the composting raw material). The initial moisture content of the compost mixture was adjusted to 60%. After the composting materials were mixed evenly, they were transferred to the composting reactor. The composting cycle was 36 days, the aeration rate was 0.8 L / min, and the aeration frequency was 10 min on / 20 min off. During the composting period, the material was turned over with a shovel.

[0033] After composting, the total organic carbon (TOC) content decreased from 53% to 44%, with a TOC loss rate of 17%; the humification coefficient (HR) was 29%; the humic acid ratio (PHA) and degree of polymerization (DP) were 61% and 1.59, respectively. The high PHA and DP values ​​indicate that the tea residue extract effectively increased the molecular weight and structural complexity of HS.

[0034] Example 3 A method for promoting the aerobic composting and humification process of biogas residue, the specific steps of which are as follows: (1) Tea waste such as tea dregs, tea seed shells, and tea tree branches and leaves are cut and crushed and passed through a 10-mesh sieve to obtain dregs; the dregs are mixed with ultrapure water at a mass ratio of 1:8 and stirred continuously for 1 hour in a constant temperature water bath at 40℃, and then filtered to obtain tea dregs extract.

[0035] (2) A high C / N ratio auxiliary material (a mixture of straw, sawdust, and mushroom residue in a mass ratio of 6:1:3) was mixed with kitchen waste biogas residue at a C / N ratio of 30:1 to obtain composting raw material. Then, tea residue leachate was added (the amount added was 12% of the wet basis mass of the composting raw material). The initial moisture content of the compost mixture was adjusted to 70%. After the composting materials were mixed evenly, they were transferred to the composting reactor. The composting cycle was 36 days, the aeration rate was 1.0 L / min, and the aeration frequency was 10 min on / 20 min off. During the composting period, the material was turned over with a shovel.

[0036] After composting, the total organic carbon (TOC) content decreased from 62% to 40%, with a TOC loss rate of 20%; the humification coefficient (HR) was 27%; the humic acid ratio (PHA) and degree of polymerization (DP) were 59% and 1.43, respectively. The high PHA and DP values ​​indicate that the tea residue extract effectively increased the molecular weight and structural complexity of HS.

[0037] Comparative Example 1 A method for promoting the aerobic composting and humification process of biogas residue, the specific steps of which are as follows: The high C / N ratio auxiliary material (a mixture of straw, sawdust, and mushroom residue in a mass ratio of 6:1:3) was mixed with kitchen waste biogas residue to obtain compost raw material, with a C / N ratio of 25:1. The initial moisture content was then adjusted to 60%. After thorough mixing, the compost material was transferred to the composting reactor. The composting cycle was 36 days, with an aeration rate of 0.8 L / min and an aeration frequency of 10 minutes on / 20 minutes off. The material was turned over with a shovel during composting.

[0038] After composting, the total organic carbon (TOC) content decreased from 56% to 37%, with a TOC loss rate of 33%; the humification factor (HR) was 23%; and the humic acid ratio (PHA) and degree of polymerization (DP) were 46% and 0.86, respectively. (The difference from Example 2 is that the addition of tea residue extract was omitted.) Comparative Example 2 A method for promoting the aerobic composting and humification process of biogas residue, the specific steps of which are as follows: A high-C / N ratio auxiliary material (a mixture of straw, sawdust, and mushroom residue in a mass ratio of 6:1:3) was mixed with kitchen waste biogas residue at a C / N ratio of 25:1 to obtain compost raw material. Then, tea polyphenols were added (at 1% of the wet basis mass of the compost raw material) to adjust the initial moisture content to approximately 60%. After thorough mixing, the compost material was transferred to the composting reactor. The composting cycle was 36 days, with an aeration rate of 0.8 L / min and an aeration frequency of 10 minutes on / 20 minutes off. During composting, the material was turned over with a shovel.

[0039] After composting, the total organic carbon (TOC) content decreased from 55% to 42%, with a TOC loss rate of 21%; the humification factor (HR) was 27%; and the humic acid ratio (PHA) and degree of polymerization (DP) were 56% and 1.27, respectively. (The difference from Example 2 is that the tea residue extract was replaced with tea polyphenols.) As can be seen from Example 2 and Comparative Example 2, compared with the pure polyphenol system, tea residue extract can supplement the release of tea polysaccharides, theanine and other soluble organic matter. These can serve as precursors of humic substances to prolong the humification process and enhance the diversity and complexity of humic acid molecular structures. At the same time, it can regulate the metabolic strategies of microorganisms and improve their utilization efficiency of organic matter.

[0040] Comparative Example 3 A method for promoting the aerobic composting and humification process of biogas residue, the specific steps of which are as follows: A high-C / N ratio auxiliary material (a mixture of straw, sawdust, and mushroom residue in a mass ratio of 6:1:3) was mixed with kitchen waste biogas residue at a C / N ratio of 25:1 to obtain compost raw material. Then, catechol (1% of the wet basis mass of the compost raw material) was added to adjust the initial moisture content to 60%. After the compost material was thoroughly mixed, it was transferred to the compost reactor. The composting cycle was 36 days, with an aeration rate of 0.8 L / min and an aeration frequency of 10 minutes on / 20 minutes off. During composting, the material was turned over with a shovel.

[0041] After composting, the total organic carbon (TOC) content decreased from 58% to 47%, with a TOC loss rate of 23%; the humification factor (HR) was 27%; and the humic acid ratio (PHA) and degree of polymerization (DP) were 53% and 1.34, respectively. (The difference from Example 2 is that the tea residue extract was replaced with catechol.) This invention effectively promotes the conversion of organic matter into humus by adding tea residue leachate. Organic carbon loss is reduced by nearly 50%; the humification process is effectively accelerated, with humic acid content increasing by over 30% and HA / FA ratio improving by over 80%; aerobic composting efficiency is significantly enhanced. This method utilizes tea residue and other tea industry waste to prepare compost additives, with active ingredients mainly consisting of natural organic matter such as tea polyphenols. Compared to mineral fertilizers and synthetic additives, it effectively avoids soil salinity imbalance and biotoxicity problems, contributing to the protection of soil ecosystem diversity and stability. Based on waste resource utilization, this method reduces waste treatment costs and dependence on mineral fertilizers and synthetic additives, combining economic efficiency with environmental friendliness, aligning with green economic and sustainable development goals.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for promoting the aerobic composting and humification process of biogas residue, characterized in that, Includes the following steps: After crushing and sieving tea industry waste, add it to water and stir thoroughly. Filter the solution to obtain tea residue leachate. The biogas residue and high C / N auxiliary materials are mixed according to the carbon-nitrogen ratio to obtain composting raw materials; Tea residue extract is added to the composting raw materials, the moisture content is adjusted, and then aerobic fermentation is carried out to obtain the compost product.

2. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The tea industry waste is at least one of tea residue, tea seed shells, and tea tree branches and leaves; the mass ratio of the tea industry waste to water is 1:8 to 1:12; the stirring is carried out by continuous stirring for 1 hour in a constant temperature water bath at 30 to 40°C.

3. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The biogas residue is the solid residue after anaerobic digestion of organic waste; the organic waste includes at least one of wet waste, feces and sludge.

4. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The high C / N auxiliary material is a mixture of straw, sawdust and mushroom residue in a mass ratio of (6~8):(1~2):(2~3); the particle size of the high C / N auxiliary material is 1~2mm.

5. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The carbon-nitrogen ratio is 20:1 to 30:

1.

6. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The moisture content is 50%~70%.

7. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The amount of tea residue leachate added is 8% to 12% of the wet basis mass of the compost raw materials.

8. The method for promoting the aerobic composting and humification process of biogas residue according to claim 1, characterized in that, The aerobic fermentation time is 36 days, the aeration rate is 0.6~1.0L / min, and the aeration frequency is 10min on / 20min off.