Pretreatment method of mixed traditional Chinese medicine residues before aerobic composting

Abstract

The invention discloses a pretreatment method before aerobic composting of mixed traditional Chinese medicine residues, which comprises the following steps: crushing the mixed traditional Chinese medicine residues according to particle sizes by a flat grinding method, then carrying out high-temperature steam explosion, carrying out constant-temperature reaction on the obtained mixed traditional Chinese medicine residues and a deep eutectic solvent at 80-100 DEG C, and carrying out enzymolysis by using cellulase and ligninase at 50-60 DEG C to obtain the mixed traditional Chinese medicine residues. And finally, mixing with a compound fermentation inoculant which is streptomyces microflavus and bacillus subtilis, and reacting for 6-12 hours, so that through a multi-step comprehensive pretreatment process, active antibacterial factors are effectively eliminated, the opening degree of cellulose and the degradability of lignin are improved, the active antibacterial factors are effectively eliminated, and the degradation rate of lignin is improved. The degradation rate of cellulose and lignin in the traditional Chinese medicine residues is remarkably improved, and the degradation efficiency, the composting efficiency and the composting quality of the traditional Chinese medicine residues are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of traditional Chinese medicine residue treatment, and in particular relates to a pretreatment method for mixed traditional Chinese medicine residue before aerobic composting. Background Art

[0002] As a by-product of traditional Chinese medicine production, Chinese herbal medicine residue is rich in organic matter. However, it is difficult to degrade because it contains a large amount of cellulose and lignin. In addition, the active antibacterial factors inhibit the fermentation efficiency of microorganisms, which becomes the main obstacle to the aerobic composting of Chinese herbal medicine residue and makes it difficult to meet the pretreatment requirements of aerobic composting.

[0003] Existing pretreatment technologies, such as drying and crushing, simple high-temperature steaming and chemical treatment, have limited effects and are difficult to meet the needs of efficient composting. The Chinese patent with publication number CN116332704A discloses a method for preparing and using a bio-organic fertilizer made from Chinese medicinal residues, which mainly involves drying and crushing the Chinese medicinal residues, adding a composite fermentation agent (Streptomyces slender and Bacillus subtilis), adjusting the carbon-nitrogen ratio, composting and fermenting, drying and cooling, and screening. However, the drying and crushing process cannot effectively open the cellulose and lignin structures, and the degradation efficiency is low. Simple high-temperature aerobic composting cannot effectively remove antibacterial factors, which affects the activity of microorganisms. The Chinese patent with publication number CN115304410A discloses a method for treating solid waste of Chinese herbal medicines. After drying and crushing in the sun, straw, urea and water are added and stirred evenly, and a composite agent of organic fertilizer fermentation bacteria is further added. The subsequent composting process can be regulated according to the organic rate of the medicinal residues, but the antibacterial factors are not effectively treated, which affects the composting effect. Chinese patent publication number CN113943179A discloses a method for promoting aerobic composting of Chinese medicine solid waste by adding residual sludge, wherein the medicine residue is squeezed and dehydrated, air-dried, added with sludge for mixed fermentation, and allowed to stand. However, the squeezing and air-drying steps are cumbersome and inefficient, and sludge as an auxiliary material has potential pollution problems, and the treatment effect on antibacterial factors is not obvious.

[0004] Therefore, the prior art mostly adopts simple crushing, drying or high temperature treatment, which cannot fully open the compact structure of cellulose and lignin in microstructure, resulting in slow degradation and low composting efficiency. Chinese medicine residues contain a variety of active antibacterial factors, which are not effectively removed in existing pretreatment technologies, directly affecting the activity of microorganisms and the efficiency of the composting process. The steps of high temperature stewing, extrusion dehydration, soaking, etc. are cumbersome, energy consumption is high, and they are not suitable for large-scale industrial applications. At the same time, these methods still have limited effects on the degradation of lignin and cellulose. Although composite fermentation agents are used in some patents, due to the inadequate pretreatment in the early stage, the effect of the agent is difficult to give full play, resulting in poor composting effect. Summary of the invention

[0005] In view of the problem that it is difficult to meet the needs of aerobic composting pretreatment in the prior art, the present invention provides a pretreatment method for mixed Chinese medicine residues before aerobic composting. Through a multi-step comprehensive pretreatment process, active antibacterial factors are effectively eliminated, the opening degree of cellulose and the degradability of lignin are improved, and the active antibacterial factors are effectively eliminated, the degradation rate of cellulose and lignin in the Chinese medicine residues is significantly improved, and the degradation efficiency, composting efficiency and composting quality of the Chinese medicine residues are significantly improved.

[0006] The present invention is achieved through the following technical solutions: A pretreatment method for mixed Chinese medicine residues before aerobic composting comprises the following steps: S1, grinding the mixed Chinese medicine residue to be aerobic composted to a particle size of 0.5-2 mm by flat grinding, wherein the particle size of 0.5-2 mm destroys the cellulose and lignin structure of the Chinese medicine residue, increases its reaction activity, and increases the surface area of ​​the Chinese medicine residue particles, and then performs high-temperature steam explosion to obtain the mixed Chinese medicine residue with dispersed fiber bundles; S2, reacting the mixed Chinese medicine residues dispersed from the fiber bundles with a low eutectic solvent at a constant temperature of 80-100° C. to obtain the mixed Chinese medicine residues treated with the low eutectic solvent; S3, the mixed Chinese medicine residue treated with the low eutectic solvent is first enzymatically hydrolyzed with cellulase and ligninase at 50-60°C to obtain the enzymatically hydrolyzed mixed Chinese medicine residue, which is then mixed with a composite fermentation agent and reacted for 6-12 hours. The composite fermentation agent is Streptomyces tenuifolius and Bacillus subtilis, thereby completing the pretreatment of the mixed Chinese medicine residue before aerobic composting.

[0007] Preferably, the moisture content of the mixed Chinese medicinal residue in S1 is less than 30%.

[0008] Preferably, S1 grinds the mixed Chinese medicine residue by a flat grinder for 12-20 min, the rotation speed of the rotating flat grinding disc in the flat grinder is 1400-1800 rpm, the angle formed by the rotating flat grinding disc and the fixed grinding disc is 12°~18°, and the temperature inside the flat grinder is controlled below 60°C.

[0009] Preferably, the temperature during high temperature steam explosion in S1 is 190° C.-210° C., the pressure is 1.2-1.8 MPa, and the duration is 6-8 min.

[0010] Preferably, S2 first dries the mixed Chinese medicine residue dispersed from the fiber bundle to a moisture content of ≤15% to obtain dried Chinese medicine residue, and then the dried Chinese medicine residue reacts with the low eutectic solvent at the temperature.

[0011] Furthermore, the low eutectic solvent described in S2 is composed of choline chloride and urea in a molar ratio of 1:(2-5), and the dried traditional Chinese medicine residue and the low eutectic solvent are reacted at a constant temperature of 80-100°C in a mass ratio of (3-10):100.

[0012] Furthermore, the dried Chinese medicine residue and the low eutectic solvent are isothermally reacted at the temperature for 1-4 h.

[0013] Preferably, S3 washes the mixed Chinese medicine residue treated with the low eutectic solvent to neutrality, and then dehydrates the mixture to obtain dehydrated Chinese medicine residue. The dehydrated Chinese medicine residue is enzymolyzed with cellulase and ligninase at 50-60°C for 12-24 h.

[0014] Furthermore, the mass ratio of the total amount of the cellulase and the ligninase to the dehydrated Chinese medicinal residue is 1:20. In terms of the percentage of dosage, the cellulase is 70%-80%, and the ligninase is 20%-30%.

[0015] Preferably, in S3, the mass ratio of Streptomyces tenuifolius to Bacillus subtilis is 1:4, and the mass ratio of the mixed Chinese medicine residue after enzymatic hydrolysis to the composite fermentation bacterial agent is 1000:1.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses a pretreatment method for mixed Chinese medicine residues before aerobic composting. The mixed Chinese medicine residues are subjected to shear force, impact force and friction force applied by a flat grinding method, and their chemical bonds are broken or deformed, thereby increasing the exposure of cellulose and lignin, causing the material structure to change, thereby achieving the purpose of refinement and crushing. The particle size of 0.5-2 mm destroys the cellulose and lignin structure of the Chinese medicine residues, increases their reaction activity, and increases the surface area of ​​the Chinese medicine residue particles. Compared with other high-energy consumption and high-impact crushing methods, the gentle treatment method of the flat grinding method reduces excessive crushing and heat accumulation, protects the composition of the material, has relatively low energy consumption, and is suitable for large-scale industrial applications. High-temperature steam explosion treatment uses high-temperature and high-pressure steam to physically decompose the cellulose and lignin in the Chinese medicine residues, destroy their compact molecular structure, and make these difficult-to-degrade components easier to be decomposed and converted in subsequent processing steps. At the same time, the steam can penetrate the cell wall and tissue of the Chinese medicine residues, rupture the cell wall, and release substances including antibacterial factors (heat-sensitive proteins, phenolic compounds or other active ingredients) in the cells. These factors usually inhibit the fermentation efficiency of microorganisms and affect the composting effect. At high temperatures, they denature, degrade or inactivate, thereby reducing the antibacterial activity, which can promote the activity and reproduction of microorganisms in the subsequent composting process and improve the treatment efficiency. The effective contact between the low eutectic solvent and the surface of the cellulose molecule leads to the gradual dissociation of the hydrogen bonds between the cellulose molecular chains, and the cellulose structure becomes looser, which enhances the reactivity of the subsequent enzymatic hydrolysis. With the dissociation of hydrogen bonds, hydroxyl groups and other reactive sites are more exposed, which promotes the further interaction between cellulose and solvent, creating conditions for subsequent degradation and transformation; the cross-linking bonds of lignin gradually break and gradually transform into low molecular weight aromatic compounds. After treatment, some hydrophobic groups of lignin are neutralized by the solvent, increasing the interaction with enzymes and microorganisms in the aqueous phase and promoting subsequent biodegradation. The long-chain cellulose polymer is gradually hydrolyzed by cellulase into shorter fibers and monosaccharides, and its network structure becomes looser, increasing the contact area between cellulose and enzymes and accelerating the enzymatic hydrolysis process. The partial degradation of lignin helps its own decomposition, promotes the contact between these components and enzymes by reducing the wrapping of cellulose, reduces the inhibitory effect of lignin on enzymatic hydrolysis, and improves the overall enzymatic hydrolysis efficiency. As cellulose and lignin degrade, the overall structure of the Chinese medicine residue becomes looser and easier to handle, which helps improve aeration and moisture management during composting, thereby accelerating the composting process. Streptomyces tenuifolius decomposes complex organic matter such as residual cellulose, starch and protein into simple small molecules such as sugars, amino acids and short-chain fatty acids by secreting a variety of enzymes, which can be further converted into stable humus by microorganisms during the composting process. The secondary metabolites produced during the growth of Streptomyces tenuifolius can promote the further decomposition of organic matter, and through interaction with other microorganisms, it also accelerates the degradation of complex organic matter.The various exoenzymes secreted by Bacillus subtilis can degrade the residual complex organic matter in the material. The organic acids produced in the metabolic process can reduce the pH value, which is conducive to the degradation of organic matter. It can also inhibit the growth of some harmful microorganisms, ensuring that beneficial microorganisms dominate the composting process. Enzymes such as lignin peroxidase and laccase secreted by Streptomyces pyogenes can oxidize and decompose antibacterial substances in Chinese medicine residues, making the composting environment more suitable for the active activities of microorganisms. Streptomyces pyogenes can inhibit the growth of some harmful pathogenic microorganisms, help degrade antibacterial factors, and optimize the structure of composting microbial communities. Bacillus subtilis consumes nutrients in the environment through rapid reproduction and metabolism, and competitively excludes harmful microorganisms by occupying favorable positions on the surface and in the microenvironment, effectively reducing the impact of antibacterial factors, making the microbial community in the composting process more stable and efficient. Antibiotics such as antimicrobial peptides produced by Bacillus subtilis can inhibit or kill residual pathogens, ensure the safety and effectiveness of composting, and provide advanced technical means for the resource utilization of Chinese medicine residues. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Electron microscope image of Chinese medicine residue after crushing using existing technology.

[0018] Figure 2 This is an electron microscope image of the Chinese medicine residue after being crushed by flat grinding in the experimental group of Case 1 of the present invention.

[0019] Figure 3 This is an electron microscope image of the Chinese medicine residue after being crushed by flat grinding and then exploded by high-temperature steam in the experimental group of Case 1 of the present invention.

[0020] Figure 4 This is an electron micrograph of the Chinese medicine residues of the experimental group of Case 1 of the present invention after being treated with a low eutectic solvent. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0022] The present invention discloses a pretreatment method for mixed Chinese medicine residues before aerobic composting, which specifically comprises the following steps: Step 1, raw material preparation: Select mixed Chinese medicine residue with a moisture content of less than 30%. If it is higher than 30%, dry it to avoid excessive adhesion or clogging of the equipment in step 2.

[0023] Step 2, crushing and mixing: The mixed material is crushed by flat grinding, and the particle size of the crushed particles is 0.5-2 mm.

[0024] 1. Equipment name and specifications Equipment Name: Pan Mill Model: PM-5025 flat grinder, its main components include: rotating flat grinding disc, fixed grinding disc, feed port, discharge port, and adjustment device.

[0025] 2. Process and parameters Step 2a: Feed It is evenly fed into the space between the rotating flat grinding disc and the fixed grinding disc of the flat grinder through the feed port.

[0026] Step 2b: Grinding Process Rotating flat grinding disc speed: 1400-1800 RPM (the specific speed can be adjusted according to the characteristics of the material and the specifications of the equipment) Applied force: The flat grinder grinds the Chinese medicine residue through the shear force, impact force and friction force between the rotating flat grinding disc and the fixed grinding disc.

[0027] Grinding disc angle: The angle formed by the rotating flat grinding disc and the fixed grinding disc is set to 12°~18° to optimize the shearing and grinding effects and ensure particle uniformity.

[0028] Processing temperature: During the grinding process, the internal temperature of the equipment is controlled below 60°C to avoid overheating and changes in material properties.

[0029] Step 2c: Particle size adjustment Target particle size: The particle size of the Chinese medicine residue after flat grinding is controlled at 0.5-2 mm. By adjusting the gap between the rotating flat grinding disc and the fixed grinding disc, the particle size of the final material can be controlled to meet the requirements of subsequent processing.

[0030] Step 2d: Material Collection The ground materials are discharged from the outlet of the flat mill, collected and directly enter the next step of high-temperature steam explosion treatment.

[0031] 3. Flat grinding disc design: The surface of the grinding disc is designed with tiny grooves and convex structures to increase the force points of the material during the grinding process and improve the grinding efficiency.

[0032] Adjustment device: The flat grinder is equipped with a precise gap adjustment device, which can accurately adjust the shortest vertical distance and angle between the rotating flat grinding disc and the fixed grinding disc according to the material properties and grinding requirements. The material is evenly sheared and rubbed on the rotating flat grinding disc, avoiding excessive crushing and uneven crushing in a single direction, ensuring the uniformity and consistency of the particles.

[0033] The processing time is 12-20 minutes (depending on whether the discharge size meets the standard. If the discharge size does not meet the standard, it will continue to be sent to the flat grinder and the processing time is the superimposed time).

[0034] Step 3, high temperature steam explosion treatment: The crushed mixture is placed in a high-temperature steam explosion device, with the temperature controlled at 190℃-210℃, the pressure at 1.2-1.8 MPa, and the duration at 6-8 minutes. High-temperature steam explosion can further effectively destroy the structure of cellulose and lignin and enhance their degradability. The specific steps are as follows: Step 3a, material preparation: The Chinese medicine residues crushed by the flat grinding method are evenly placed into the processing chamber of the high-temperature steam explosion device.

[0035] Step 3b, sealing the processing chamber: Close and seal the process chamber to ensure there are no leaks.

[0036] Step 3c, heating and pressurization: Start the heating program to increase the temperature in the processing chamber to 190°C-210°C, then turn on the steam generator to increase the pressure in the processing chamber to 1.2-1.8 MPa.

[0037] Step 3d, maintain processing time: At the above temperature and pressure, the treatment time is maintained for 6-8 minutes to ensure that the steam can fully penetrate the material and destroy the structure of cellulose and lignin.

[0038] Step 3e, rapid pressure reduction and temperature reduction: After the treatment time is over, the pressure and temperature in the treatment chamber are quickly reduced. The pressure is reduced to normal pressure and the temperature is reduced to room temperature by exhausting steam or circulating cooling water. (Cooling rate: 25-28℃ / min, pressure reduction rate: 0.3-0.4 MPa / min) Step 3f, material removal: Open the processing chamber and take out the Chinese medicine residue after high-temperature steam explosion treatment.

[0039] Step 3g, subsequent processing: The treated Chinese medicine residue is dried to a moisture content of ≤15% and then transferred to a deep eutectic solvent (DES) treatment tank for the next step of treatment.

[0040] Step 4, deep eutectic solvent treatment: The specific steps are as follows: Step 4a, preparing a low eutectic solvent by heating and stirring: Choline chloride is used as a hydrogen bond acceptor and directly mixed with urea (hydrogen bond donor) at a molar ratio of 1: (2-5) without adding other solvents, and heated to 80°C-100°C, and stirred continuously until it is completely dissolved to form a uniform and clear liquid deep eutectic solvent (DES).

[0041] Before preparation, the hydrogen bond donor and acceptor must be dried first, especially choline chloride must be placed in an oven for 4-6 hours. The amount of DES is selected according to the mass ratio of dried Chinese medicine residue: DES = (3-10): 100.

[0042] Step 4b, pre-processing material preparation: The Chinese medicine residues after high-temperature steam explosion treatment are evenly placed in the treatment pool.

[0043] Step 4c, adding a deep eutectic solvent: Add the prepared low eutectic solvent into the treatment tank, according to the previous proportions, to ensure that the material is completely immersed in the solvent.

[0044] Step 4d, constant temperature treatment: The temperature of the treatment tank is controlled at 80℃-100℃, kept constant, and stirred to ensure sufficient contact between the solvent and the Chinese medicine residue. The treatment time is 1-4 hours.

[0045] During the isothermal treatment, the deep eutectic solvent (DES) effectively contacts the surface of cellulose molecules, causing the hydrogen bonds between cellulose molecular chains to gradually dissociate. This dissociation of hydrogen bonds makes the cellulose structure looser and enhances its reactivity in the subsequent enzymatic hydrolysis process. With the dissociation of hydrogen bonds between cellulose chains, the hydroxyl groups and other reactive sites in cellulose are more exposed, which promotes the further interaction between cellulose and solvent and creates conditions for subsequent degradation and transformation. Lignin is a highly cross-linked aromatic polymer. Under high-temperature DES treatment, the cross-linking bonds (such as ether bonds and ester bonds) of lignin gradually break. The breaking of these bonds leads to the deconstruction of the complex network structure of lignin, causing it to gradually transform from its original high molecular weight state to low molecular weight aromatic compounds. Lignin usually has a high hydrophobicity, which hinders its biodegradation during composting. After isothermal treatment, some hydrophobic groups are neutralized by the solvent, and the hydrophobicity of lignin is reduced, thereby increasing its interaction with enzymes and microorganisms in the water phase and promoting subsequent biodegradation.

[0046] Step 4e, Rinse and Neutralize: After the treatment, the material is taken out of the treatment tank and rinsed with clean water to remove the residual low eutectic solvent until the material is neutral.

[0047] Step 4f, pre-enzymatic treatment: The washed material is dehydrated in preparation for the next enzymatic treatment.

[0048] Step 5, enzymatic treatment: Then add cellulase and ligninase (mass ratio of materials: cellulase / ligninase = 20:1). According to the percentage of dosage, the cellulase is 70%-80%, the ligninase is 20%-30%, the enzymolysis temperature is 50°C-60°C, and the time is 12-24 hours.

[0049] Under the action of cellulase, the long-chain cellulose polymer is gradually hydrolyzed into shorter fibers (such as cellobiose) and monosaccharides (such as glucose). As cellulose breaks down into smaller sugar molecules, the cellulose network structure becomes looser. This loosening helps to increase the contact area between cellulose and enzymes, further accelerating the enzymatic hydrolysis process. The partial degradation of lignin not only helps its own decomposition, but also promotes the contact between these components and enzymes by reducing the wrapping of cellulose, reducing the inhibitory effect of lignin on enzymatic hydrolysis, and improving the overall enzymatic hydrolysis efficiency. As cellulose and lignin degrade, the overall structure of the Chinese medicine residue becomes looser and easier to handle. This loosening of the structure helps to improve aeration and moisture management during the composting process, thereby accelerating the composting process.

[0050] Step 6, microbial pretreatment: The treated material is mixed with a composite fermentation agent (the mass ratio of Streptomyces flavonoids and Bacillus subtilis powder is 1:4). The dosage of the composite fermentation agent is determined by the bacterial concentration per unit weight of the material. If the number of bacteria in the agent is 1 billion / gram of powder, the concentration in the material must reach 1 million bacteria per gram of material, that is, the weight ratio of the material to the agent is 1000:1, which means that 1 gram of dry powder of the agent is added to every 1000 grams of the material, and the reaction is allowed to stand for 6-12 hours to further degrade residual organic matter and antibacterial factors.

[0051] Streptomyces aureofaciens is a common actinomycete in soil with strong cellulose decomposition ability. It can secrete a variety of enzymes (such as cellulase, amylase, protease, etc.) to decompose complex organic matter such as residual cellulose, starch and protein in the material into simple small molecules such as sugars, amino acids and short-chain fatty acids. These small molecules can be further utilized by microorganisms in the subsequent composting process and converted into stable humus. Streptomyces aureofaciens produces a variety of secondary metabolites during its growth, which can not only promote the further decomposition of organic matter, but also accelerate the degradation of complex organic matter in the material through interaction with other microorganisms. Bacillus subtilis is a bacterium with strong tolerance and decomposition ability, which can secrete a variety of exoenzymes, such as cellulase, pectinase, protease and lipase. These enzymes can further degrade the residual complex organic matter in the material, especially those components that have not been completely degraded in the previous treatment process. Bacillus subtilis produces organic acids during metabolism, which can reduce the pH value of the material and create an acidic environment that is more conducive to the degradation of organic matter. In addition, the low pH value can also inhibit the growth of some harmful microorganisms, ensuring that beneficial microorganisms dominate the composting process.

[0052] Streptomyces leucodermi can secrete enzymes such as lignin peroxidase and laccase, which can oxidize and decompose antimicrobial substances in Chinese medicine residues, such as phenols and polyphenolic compounds. These antimicrobial substances usually inhibit the activity of other microorganisms. Through the action of Streptomyces leucodermi, the concentration of these antimicrobial factors can be reduced, making the entire composting environment more suitable for the active activities of microorganisms. Streptomyces leucodermi itself has antimicrobial activity, which can inhibit the growth of some harmful pathogenic microorganisms and further eliminate the unfavorable factors in the composting process. This inhibitory effect not only helps to degrade antimicrobial factors, but also optimizes the structure of composting microbial communities. Bacillus subtilis consumes nutrients in the environment through rapid reproduction and metabolism, and competitively excludes harmful microorganisms by occupying favorable positions on the surface of materials and in the microenvironment. This competitive effect effectively reduces the impact of antimicrobial factors, making the microbial community in the composting process more stable and efficient. Bacillus subtilis can also produce antibiotic substances such as antimicrobial peptides to further inhibit or kill residual pathogens in the material, ensuring the safety and effectiveness of composting.

[0053] Example Case 1: Small-scale experiment 1 Experimental group: 50 kg of traditional Chinese medicine residue, 25 kg of crop straw and 25 kg of residual activated sludge from a municipal sewage plant were selected, the traditional Chinese medicine residue was pretreated according to the above steps, and then aerobic composting was started in combination with the crop straw and residual activated sludge.

[0054] The specific steps are as follows: The mixed Chinese medicine residue is dried to a moisture content of less than 30%, and then crushed by a PM-5025 flat grinder, with a rotating flat grinding disc speed of 1600 RPM, an angle formed by the rotating flat grinding disc and the fixed grinding disc set to 15°, a processing time of 18 minutes, an internal temperature controlled at 40°C, and a particle size of 2-5 mm after crushing; The crushed sample was placed in a high-temperature steam explosion device, the temperature was controlled at 200°C, the pressure was 1.6MPa, and the duration was 10 minutes. Then the pressure and temperature in the processing chamber were rapidly reduced, the cooling rate was 25°C / minute, the pressure reduction rate was 0.3MPa / minute, the processing chamber was opened, and the traditional Chinese medicine residue after high-temperature steam explosion treatment was taken out.

[0055] To perform the deep eutectic solvent treatment process: DES was prepared with choline chloride and urea in a molar ratio of 1:4, heated to 90°C, and stirred continuously until completely dissolved to form a uniform and clear liquid low eutectic solvent (DES). The amount of DES was selected according to the mass ratio of dry Chinese medicine residue: DES = (8): 100. After being treated at 80°C for 1 hour, the Chinese medicine residue was rinsed with clean water after the low eutectic solvent treatment until it was neutral; The material was dehydrated, and cellulase and ligninase were added, the material: cellulase / ligninase = 20:1, the amount of cellulase and ligninase was 80%:20% by percentage, the enzymatic hydrolysis temperature was 50°C, and the time was 12 hours.

[0056] The treated material was mixed with a composite fermentation agent (the mass ratio of Streptomyces leucoderma and Bacillus subtilis powder was 1:4), the weight ratio of the material to the agent was 1000:1, and the reaction was allowed to stand for 8 hours. This was the end of the pretreatment.

[0057] The final organic fertilizer was obtained by combining 25 kg of crop straw and 25 kg of residual activated sludge from a municipal sewage plant for aerobic composting.

[0058] During the fermentation process, the compost temperature, pH value and organic matter content were monitored regularly, and the cellulose, lignin content and microbial activity of the compost were tested once a week.

[0059] 2. Control group: 50 kg of traditional Chinese medicine residue, 25 kg of crop straw and 25 kg of residual activated sludge from a municipal sewage plant were selected, the traditional Chinese medicine residue was dried until the moisture content was less than 30%, and aerobic composting was carried out directly under the same composting conditions as the experimental group.

[0060] During the fermentation process, the compost temperature, pH value and organic matter content were monitored regularly, and the cellulose, lignin content and microbial activity of the compost were tested once a week.

[0061] Case 2: Large-scale production Experimental Group: 500 kg of traditional Chinese medicine residue, 250 kg of crop straw and 250 kg of residual activated sludge from a municipal sewage plant were selected and pretreated according to the steps of the experimental group in Case 1 before large-scale composting and fermentation.

[0062] During the fermentation process, the compost temperature, pH value and organic matter content were monitored regularly, and the cellulose, lignin content and microbial activity of the compost were tested once a week.

[0063] Control group: 500 kg of traditional Chinese medicine residue, 250 kg of crop straw and 250 kg of residual activated sludge from a municipal sewage plant were selected, the traditional Chinese medicine residue was dried until the moisture content was less than 30%, and aerobic fermentation was carried out directly under the same composting conditions as the experimental group.

[0064] During the fermentation process, the compost temperature, pH value and organic matter content were monitored regularly, and the cellulose, lignin content and microbial activity of the compost were tested once a week.

[0065] Comparison of application effects Figure 1 Among the traditional Chinese medicine residues crushed by existing methods, the crushing equipment type is a hammer crusher or a toothed roller crusher (commonly used traditional crushing equipment), with a rotation speed of 1200 RPM. The lower rotation speed leads to smaller shear and impact forces, and the crushing gap is usually 1-2 cm. The larger gap leads to larger crushed particles of the material and cannot fully destroy the fiber structure. The particle size is uneven, and there are a large number of unbroken fiber bundles and large particles, resulting in unsatisfactory overall crushing effect of the material. Traditional crushing methods mainly rely on mechanical impact. The fiber bundles in the traditional Chinese medicine residues after crushing remain relatively intact, and the fibers are tightly bound to each other, which cannot effectively open the structure of cellulose and lignin. Due to insufficient crushing force, the surface of the material after crushing is still relatively smooth, lacking sufficient microscopic cracks and pores, and exposed sites, making it difficult to increase the specific surface area and microbial attachment points, which is not conducive to the attachment and degradation of microorganisms.

[0066] In contrast, after being crushed using the flat grinding method, Figure 2 The fiber structure of the Chinese medicine residue is obviously broken, and the overall peeling degree of the residue surface is higher than that of the existing crushing technology. The fiber bundles are separated into smaller fiber units, the surface roughness increases, and the internal cellulose bundles of the residue are exposed, exposing more microscopic cracks and pores. These characteristics significantly increase the specific surface area and active sites of the fiber, providing more attachment points and nutrient contact surfaces for microorganisms in the aerobic composting process, thereby accelerating the degradation and transformation of organic matter.

[0067] After high temperature steam explosion treatment, Figure 3As shown in the figure, the fiber bundle after steam explosion is completely spread out and no longer looks like Figure 1 , Figure 2 The blocky structure gathered together.

[0068] After standing and reacting with the composite fermentation agent, Figure 4 , the hydrogen bonds between the cellulose chains dissociate, the exposed sites increase, and the subsequent microbial fermentation process is promoted.

[0069] Table 1: Comparison of properties of Chinese medicine residue before and after pretreatment

[0070] The parameter determination methods used are as follows: 1. Fermentation time: It includes the sum of aerobic fermentation and aging time, starting from the initial fermentation stage (the 7th day after the start of fermentation). After the temperature rises to 60°C, the duration of high-temperature fermentation is recorded, and the time node of temperature drop is also recorded until the pile temperature drops sharply. The time of aging to a moisture content of 35% is recorded.

[0071] 2Organic matter content: The high-temperature ignition method (Loss-on-Ignition, LOI) was used for measurement, and the organic matter content in the organic fertilizer of the Chinese medicinal residue compost after pretreatment was 62%, while the organic matter content in the organic fertilizer of the Chinese medicinal residue compost without pretreatment was 35%.

[0072] 3. Determination method of cellulose content and lignin content: Paradigm washing method.

[0073] 4. Determination of antibacterial activity of antibacterial factors: Inhibition zone method: In the experiment, the water extract of organic fertilizer or the treated Chinese medicine residue is directly placed on the culture medium containing pathogens for cultivation. After a certain period of time (usually 24-48 hours), the diameter of the area around which no colonies grow (i.e. the diameter of the inhibition zone) is measured. The size of the inhibition zone directly reflects the strength of the antibacterial property.

[0074] GBT39101-2020 standard: This standard specifies the inhibition zone method for determining the antibacterial properties of peptides and is one of the commonly used reference standards.

[0075] Antibacterial data Before preprocessing: Diameter of antibacterial zone: 12-20 mm (higher antibacterial activity) Note: In the traditional Chinese medicine residue that has not been pretreated, the antibacterial factors are more active and have a stronger inhibitory effect on microorganisms, so a larger inhibition zone diameter is shown in the experiment.

[0076] After preprocessing: Diameter of antibacterial zone: 3-8 mm (lower antibacterial activity) Description: After flat grinding, high-temperature steam explosion and microbial pretreatment, the antibacterial factors in the traditional Chinese medicine residue were effectively degraded or inhibited, and the antibacterial activity was significantly reduced, thus showing a smaller inhibition zone diameter in the antibacterial experiment.

Claims

1. A pretreatment method for mixed Chinese medicine residues before aerobic composting, characterized in that: The steps include: S1, crushing the mixed Chinese medicinal residue to be aerobic composted to a particle size of 0.5-2 mm by flat grinding, and then performing high-temperature steam explosion to obtain the mixed Chinese medicinal residue with dispersed fiber bundles; S2, reacting the mixed Chinese medicine residues dispersed from the fiber bundles with a low eutectic solvent at a constant temperature of 80-100° C. to obtain the mixed Chinese medicine residues treated with the low eutectic solvent; S3, the mixed Chinese medicine residue treated with the low eutectic solvent is first enzymatically hydrolyzed with cellulase and ligninase at 50-60°C to obtain the enzymatically hydrolyzed mixed Chinese medicine residue, which is then mixed with a composite fermentation agent and reacted for 6-12 hours. The composite fermentation agent is Streptomyces tenuifolius and Bacillus subtilis, thereby completing the pretreatment of the mixed Chinese medicine residue before aerobic composting.

2. The pretreatment method before aerobic composting of mixed Chinese medicinal residues according to claim 1, characterized in that: The moisture content of the mixed Chinese medicinal residue described in S1 is less than 30%.

3. The pretreatment method before aerobic composting of mixed Chinese medicinal residues according to claim 1, characterized in that: S1 grinds the mixed Chinese medicine residues by a flat grinder for 12-20 min, the rotation speed of the rotating flat grinding disc in the flat grinder is 1400-1800 rpm, the angle formed by the rotating flat grinding disc and the fixed grinding disc is 12°~18°, and the temperature inside the flat grinder is controlled below 60°C.

4. The pretreatment method before aerobic composting of mixed Chinese medicinal residues according to claim 1, characterized in that: The temperature of S1 during high temperature steam explosion is 190℃-210℃, the pressure is 1.2-1.8 MPa, and the duration is 6-8 min.

5. The pretreatment method before aerobic composting of mixed Chinese medicinal residues according to claim 1, characterized in that: S2 first dries the mixed Chinese medicine residues dispersed from the fiber bundles to a moisture content of ≤15% to obtain dried Chinese medicine residues, and then the dried Chinese medicine residues react with the low eutectic solvent at the temperature.

6. The pretreatment method before aerobic composting of mixed Chinese medicinal residues according to claim 5, characterized in that: The low eutectic solvent described in S2 is composed of choline chloride and urea in a molar ratio of 1:(2-5), and the dried traditional Chinese medicine residue and the low eutectic solvent are reacted at a constant temperature of 80-100°C in a mass ratio of (3-10):

100.

7. The pretreatment method of mixed Chinese medicinal residues before aerobic composting according to claim 6, characterized in that: The dried Chinese medicine residue and the low eutectic solvent are reacted at the temperature for 1-4 h.

8. The pretreatment method before aerobic composting of mixed Chinese medicinal residues according to claim 1, characterized in that: S3 washes the mixed Chinese medicine residue treated with the low eutectic solvent to neutrality, and then dehydrates it to obtain dehydrated Chinese medicine residue. The dehydrated Chinese medicine residue is enzymolyzed with cellulase and ligninase at 50-60°C for 12-24 hours.

9. The pretreatment method of mixed Chinese medicinal residues before aerobic composting according to claim 8, characterized in that: The mass ratio of the total amount of the cellulase and ligninase to the dehydrated Chinese medicinal residue is 1:

20. In terms of percentage of dosage, the cellulase is 70%-80% and the ligninase is 20%-30%.

10. The pretreatment method of mixed Chinese medicinal residues before aerobic composting according to claim 1, characterized in that: In S3, the mass ratio of Streptomyces tenuifolius to Bacillus subtilis is 1:4, and the mass ratio of the mixed Chinese medicine residue after enzymatic hydrolysis to the composite fermentation agent is 1000:1.

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