Method for harmlessly treating biogas residues and poplar leaves through earthworms and earthworm compound feed

Abstract

The invention relates to a method for harmlessly treating biogas residues and poplar leaves through earthworms and earthworm compound feed, and belongs to the technical field of solid waste treatment and feed recycling. The method comprises the following steps: mixing biogas residues and poplar leaves, and carrying out aerobic composting to obtain a mixed base material; putting earthworms into the mixed base material for earthworm composting to obtain composted earthworms; on the basis of the total dosage of the biogas residues and the poplar leaves, the dosage of the biogas residues is 60-80 wt%, and the dosage of the poplar leaves is 20-40 wt%. According to the earthworm compound feed disclosed by the invention, the biogas residues and the poplar leaves are mixed and then are subjected to aerobic composting, and the earthworms are put into the mixed base material and are subjected to earthworm composting, so that not only can the high-protein earthworms be obtained, but also the survival rate and the yield of the earthworms can be improved; the weight gain rate, the specific growth rate and the survival rate of the lobsters can be remarkably increased, and the feed coefficient is reduced.

Description

Technical Field

[0001] This invention relates to a method for harmlessly treating biogas residue and poplar leaves using earthworms, and to earthworm compound feed, belonging to the technical field of solid waste treatment and feed resource utilization. Background Technology

[0002] Solid waste management is an urgent challenge requiring intervention at all levels to achieve a sustainable and healthy environment. The generation of solid waste is constantly increasing, and its treatment requires significant land use. Improper disposal methods such as open dumping and open burning further exacerbate environmental pollution. Adopting scientific, environmentally friendly, and sustainable waste management technologies is key to addressing this challenge. Currently, various physical, chemical, and biological technologies have been developed for solid waste management, with biological methods (such as biogasification, composting, and vermicomposting) receiving increasing attention. Vermicomposting is an environmentally friendly method for treating biodegradable waste. Most of the non-toxic, biodegradable components in solid waste can be efficiently utilized as composting feedstock. Various biodegradable wastes, including agricultural waste, industrial waste, municipal solid waste, sludge, and papermaking waste, have been used as feedstock for vermicomposting.

[0003] Biogas residue mainly comes from agricultural and forestry waste, as well as the residue produced after some agricultural organic waste undergoes biogas fermentation. During the anaerobic fermentation process, the carbon, hydrogen, oxygen, and other elements in these raw materials are gradually decomposed and transformed, eventually producing gases such as methane and carbon dioxide, while the remaining organic matter forms biogas residue.

[0004] Biogas residue is rich in organic matter and nutrients, possessing both fast-acting and slow-release fertilizer properties. It can be directly applied to farmland or horticultural crops as a high-quality organic fertilizer. Continuous application of biogas residue can not only increase crop yields but also improve soil structure and fertility. In addition, biogas residue can be mixed with inorganic fertilizers such as phosphate rock powder to produce compound fertilizers, thereby improving phosphorus utilization.

[0005] Vermicomposting, as an environmentally friendly and efficient waste treatment method, has significant advantages in handling agricultural and forestry waste. However, traditional vermicomposting techniques still have limitations and shortcomings, such as low treatment efficiency and incomplete material conversion. Raw biogas residue has a strong pungent odor and contains harmful gases such as ammonia; directly using it for vermicomposting can cause earthworms to escape or even die.

[0006] Therefore, it is of great significance to study a composting method for earthworms that has a high survival rate and is conducive to earthworm growth. Summary of the Invention

[0007] To address the problems existing in the prior art, one of the objectives of this invention is to provide a method for the harmless treatment of biogas residue and poplar leaves using earthworms. This invention involves mixing biogas residue and poplar leaves for aerobic composting, and then placing earthworms in the mixed substrate for earthworm composting. This not only yields high-protein earthworms but also improves the survival rate and yield of earthworms. Furthermore, the compost sample obtained after earthworm composting can be used as fertilizer.

[0008] The second objective of this invention is to provide a compound earthworm feed, which, when used to feed lobsters, can significantly improve the weight gain rate, specific growth rate, and survival rate of lobsters, while reducing the feed conversion ratio.

[0009] To achieve the above objectives, a first aspect of the present invention provides a method for harmlessly treating biogas residue and poplar leaves using earthworms, the method comprising:

[0010] (1) Mix biogas residue and poplar leaves and then perform aerobic composting to obtain a mixed substrate;

[0011] (2) Earthworms are placed in a mixed substrate for earthworm composting to obtain composted earthworms;

[0012] Based on the total amount of biogas residue and poplar leaves used, the amount of biogas residue used is 60-80 wt%, and the amount of poplar leaves used is 20-40 wt%.

[0013] This invention uses poplar leaves as a conditioner to pre-treat biogas residue through aerobic composting. Introducing poplar leaves not only improves the palatability of the biogas residue but also facilitates the efficient degradation of macromolecules such as lignocellulose in the mixture. It also increases the C / N ratio during fermentation (achieving a balance of carbon and nitrogen nutrients) and the E4 / E6 ratio, allowing the mixed substrate to reach a certain "pre-stabilized" or "pre-composted" state. This shortens the composting cycle of the biogas residue waste and reduces the risk of secondary fermentation and heat generation and the production of toxic substances during subsequent vermicomposting. Furthermore, the pre-treatment fermentation process effectively removes ammonia and further adjusts pH, C / N ratio, moisture content, and organic matter content, which is more beneficial for earthworm farming. Compared to directly using biogas residue for farming, earthworm survival rates and yields are higher, and the obtained earthworms have a higher protein content, making them a high-quality protein feed source. This invention improves the utilization value of biogas residue and poplar leaves, enhances the effectiveness of vermicomposting, and increases their overall value.

[0014] As a preferred option, biogas residue is the solid waste remaining after anaerobic fermentation to produce biogas in a fermentation plant.

[0015] As a preferred embodiment, the biogas residue has a pH of 7-8, an organic carbon content of 270-320 g / kg, a total nitrogen content of 20-25 g / kg, a carbon-to-nitrogen ratio of 10-14, an organic matter content of 480-540 g / kg, and an E4 / E6 ratio of 2.8-3.2. The weakly alkaline nature of the biogas residue provides an ideal living environment for earthworms, avoiding direct stimulation and damage to their body surface and digestive system from excessively acidic or alkaline conditions. Simultaneously, it possesses good buffering capacity, neutralizing the sudden pH drop caused by organic acid production in the early stages of composting, and the potential pH increase due to ammonification in the later stages, thereby maintaining the relative stability of the compost microenvironment. If the initial acidity of the biogas residue is too high, it will directly inhibit earthworm activity and feeding; while excessive alkalinity may be toxic to earthworms, leading to escape or death. Under these preferred conditions, the organic carbon and organic matter content contains a large amount of energy and carbon sources that can be utilized by earthworms and microorganisms. The total nitrogen content and carbon-to-nitrogen ratio of this invention provide sufficient nitrogen nutrients, which is conducive to the rapid reproduction of microorganisms, thereby initiating and accelerating the composting process. If the C / N ratio is too high, the microorganisms will proliferate slowly due to insufficient nitrogen source, prolonging the composting time; if the C / N ratio is too low, nitrogen will easily volatilize in large quantities in the form of ammonia, producing an odor and causing nitrogen loss. At the same time, high concentrations of ammonia have a direct toxic effect on earthworms.

[0016] In this invention, the E4 / E6 value (the ratio of absorbance at 465 nm to 665 nm) is used as one of the indicators of compost maturity, reflecting the size and degree of condensation of humic acid molecules. The smaller the E4 / E6 value, the larger the molecular weight, and the higher the degree of condensation and aromatization of aromatic rings in the compost.

[0017] As a preferred option, the particle size of both biogas residue and poplar leaves is independently <5mm.

[0018] As a preferred option, the biogas residue and poplar leaves are first dried in the sun, and then crushed into particles with a diameter of <5mm.

[0019] As a preferred embodiment, the conditions for aerobic composting are: moisture content of 60-70 wt% and time of 15-20 days.

[0020] As a preferred method, the compost pile should be turned over every 2 to 4 days during aerobic composting.

[0021] As a preferred method, the earthworm release density is 0.1~0.3 kg / m². 3 .

[0022] As a preferred method, the conditions for vermicomposting are: temperature 20-25℃, substrate moisture content 60-70 wt%, turning the compost every 3-4 days, and composting time 20-100 days. During composting, water should be added when the substrate moisture content drops below 60 wt%. A further optimized composting time is 25-48 days. Earthworms raised for 25-48 days experience rapid weight gain, and continued composting afterward has virtually no impact on their weight.

[0023] As a preferred option, the average weight of earthworms after composting is 550~611mg.

[0024] As a preferred embodiment, based on the total amount of biogas residue and poplar leaves, the amount of biogas residue is 65-75 wt%, and the amount of poplar leaves is 25-35 wt%. Biogas residue provides abundant nitrogen, minerals, and pre-stabilized organic matter, providing ample nutrition for earthworms and microorganisms. Poplar leaves, acting as a "conditioner" and "carbon source," increase the C / N ratio of the mixture, accelerating the decomposition of organic matter while minimizing nitrogen loss in the form of ammonia. Too few poplar leaves result in a low C / N ratio and a relative excess of nitrogen, leading to significant ammonia volatilization, producing an unpleasant odor and directly toxicizing earthworms. Too many poplar leaves result in a high C / N ratio, reducing the compost pile's heat and moisture retention capabilities, making it easier for moisture and heat to dissipate. This is detrimental to the continuous activity of microorganisms and the habitat of earthworms, meaning it contains more recalcitrant lignin and cellulose. Earthworms and microorganisms need to expend more energy to decompose these stubborn substances, reducing composting efficiency.

[0025] As a preferred embodiment, the earthworm is *Eisenia fetida*.

[0026] As a preferred embodiment, the earthworm composting operation includes: putting earthworms into a mixed substrate and composting the earthworms in a breeding box.

[0027] As a preferred embodiment, the breeding box is a plastic box with holes at the bottom, and the bottom is covered with a layer of mesh.

[0028] The second aspect of the present invention is to provide the aforementioned earthworm compound feed, comprising the following components: 170-190 parts earthworm powder, 85-95 parts miscanthus, 30-40 parts corn flour, 50-60 parts rapeseed meal, 17-23 parts wheat flour, 3-5 parts calcium dihydrogen phosphate, 1.3-1.8 parts salt, 3-4 parts mealworm powder, 0.3-0.5 parts allicin, 2-3 parts vitamins, and 7-9 parts minerals;

[0029] The earthworm powder is made from earthworms that have been composted and then dried and crushed according to the method described in the first aspect above.

[0030] The earthworm powder provided by this invention can replace soybean meal in crayfish farming, and can also improve the growth performance and feed utilization rate of crayfish, improve the nutritional content of crayfish, and further enhance the quality of feed. Miscanthus sinensis is not only abundant and inexpensive, but also environmentally friendly, and can also help improve the digestibility of feed for crayfish. Through the synergistic effect between earthworm powder, Miscanthus sinensis and other components, this invention enables the compound feed to significantly improve the weight gain rate, specific growth rate and survival rate of crayfish when used in crayfish farming, while reducing the feed conversion ratio.

[0031] As a preferred embodiment, the vitamin is vitamin C.

[0032] As a preferred embodiment, the mineral is a calcium, magnesium, and phosphorus feed additive.

[0033] As a preferred method, earthworms after composting are first temporarily kept in clean water for 8-12 hours to expel the contents of their digestive tract. Then, the earthworms are dried at 50-70℃ until they reach a constant weight. The dried earthworms are then crushed and passed through an 80-100 mesh sieve to remove the sieve residue, thus obtaining the earthworm powder.

[0034] As a preferred embodiment, the earthworm compound feed comprises the following components: 180 parts earthworm powder, 90 parts miscanthus, 36 parts corn flour, 54 parts rapeseed meal, 20 parts wheat flour, 4 parts calcium dihydrogen phosphate, 1.6 parts salt, 3.6 parts yellow mealworm powder, 0.4 parts allicin, 2.4 parts vitamins, and 8 parts minerals.

[0035] As a preferred option, the earthworm compound feed is used to raise lobsters.

[0036] As a preferred embodiment, the lobster is the red swamp crayfish (Procambarus clarkii).

[0037] Compared with the prior art, the present invention has at least the following advantages:

[0038] (1) This invention improves the C / N ratio of fermentation by mixing poplar leaves as a conditioner with biogas residue and performing aerobic composting, shortens the composting cycle of biogas residue waste, and increases the utilization value of biogas residue and poplar leaves. Furthermore, the pretreatment fermentation process effectively removes ammonia substances and adjusts pH, C / N, water content and organic matter content, which is more beneficial to earthworm breeding. Compared with directly using biogas residue for breeding, the earthworm survival rate and yield are higher. Furthermore, the compost sample obtained after earthworm composting can be used as fertilizer.

[0039] (2) This invention realizes the harmless, reduced and resource-based treatment of biogas residue and poplar leaves, while producing high-value-added earthworm protein and earthworm casting organic fertilizer, which is in line with the direction of green circular agriculture.

[0040] (3) When the compound feed of the present invention is used in lobster farming, it can significantly improve the weight gain rate, specific growth rate and survival rate of lobsters, and reduce the feed conversion ratio.

[0041] (4) The earthworms raised by this invention have a protein content of up to 60%, a fat content of more than 6%, and an ash content of more than 12%. Their nutritional value is superior to that of ordinary earthworm powder and soybean meal, making them a high-quality protein feed source. Attached Figure Description

[0042] Figure 1 These are scanning electron microscope (SEM) images of the initial mixed sample obtained by mixing biogas residue and poplar leaves before aerobic composting in Example 1, and the compost sample after earthworm composting. Figure 1 In the image, 'a' is a scanning electron microscope (SEM) image of the initial mixture of biogas residue and poplar leaves before aerobic composting. Figure 1 Figure 'b' shows a scanning electron microscope (SEM) image of the compost sample after vermicomposting. The image reveals that the initial mixture exhibits a relatively dense structure and blocky consistency, while the final vermicompost sample displays a more porous, fragmented, and granular texture. This structure plays a significant role in improving soil structure, activating soil life, coordinating water and air environments, and enhancing fertilizer efficiency. This change is due to the fact that during vermicomposting, earthworms (Eisenia fetidae) feed on and tear apart the initial mixture. The decomposition of the substrate material is further promoted by various enzymes and gut microbiota activity (mainly hydrolytic bacteria) in the earthworm's gut.

[0043] Figure 2 These are Fourier transform infrared (FT-IR) spectra of the initial mixture of biogas residue and poplar leaves before aerobic composting in Example 1, and the compost sample after vermicomposting. FT-IR spectroscopy is an analytical method that helps identify chemical functional groups. Changes in absorption band intensity can be used to assess the stability of vermicompost. The FT-IR spectra at different stages show the changes in the relative intensity of the absorption bands. Both the initial mixture and the compost sample are at approximately 3450 cm⁻¹. -1 The sample exhibited a distinct OH stretching peak due to hydrogen bonding, and the peak intensities decreased in the following order: initial mixed sample > compost sample after vermicomposting. This phenomenon indicates the decomposition of phenolic compounds and carbohydrates. During the treatment, the intensity ranged from 2720.8–2723.2 cm⁻¹. -1 The range (corresponding to the hydrocarbon stretching vibration of the aliphatic methylene group) decreased. This finding suggests that the presence of reduced aliphatic structure may promote the degradation of lipids and carbohydrates. At approximately 1604.7 cm⁻¹ -1 A decrease in relative intensity was observed at the C=O stretching vibration of the amide group, the C=O of the quinone type, and / or the C=O of the hydrogen-bonded conjugated ketone. This change can be attributed to the reduction of aromatic groups during vermicomposting. Subsequently, at 1352.2 cm⁻¹, -1A peak appeared at 1102.8 cm⁻¹, which is attributed to the NO stretching vibration of the nitro group. -1 The peak intensity decreased at 770.1 and 616.7 cm⁻¹, which is attributed to the reduced content of aromatic ethers and polysaccharides. -1 The peaks observed may indicate the presence of silicate groups (Si-O-Si), aromatic ethers, and polysaccharides (CH stretching vibrations) in the compost sample. Therefore, compared to the initial levels of the organic waste raw material, the FTIR spectrum of vermicompost shows an increase in nitrogen-rich components and a decrease in aliphatic and aromatic compounds. The stabilization and humification of the organic matter implies that the compost product is safe (does not burn roots) and highly efficient (rich in humic acid and slow-release nutrients). Detailed Implementation

[0044] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0045] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0046] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0047] The biogas residue comes from the residual waste after biogas fermentation at Jiangsu Xuzhou Huaneng Ecological Technology Co., Ltd. The biogas residue has a pH of 7.40, an organic carbon content (TOC) of 294.85 g / kg, a total nitrogen (TN) content of 23.22 g / kg, a carbon-to-nitrogen ratio (C / N) of 12.71, an organic matter (OM) content of 508.32 g / kg, and an E4 / E6 content of 3.08.

[0048] The poplar leaves are sourced from Nanyang City, Henan Province. The pH of the poplar leaves is 5.19, the total organic carbon (TOC) content is 523.35 g / kg, the total nitrogen (TN) content is 22.98 g / kg, the carbon-nitrogen ratio (C / N) is 22.77, the organic matter (OM) content is 902.26 g / kg, and the E4 / E6 content is 6.35.

[0049] The crude protein content of soybean meal is 46.4615%, the crude ash content is 5.81%, and the crude fat content is 2.66%.

[0050] Vitamin: Vitamin C.

[0051] Minerals: Calcium magnesium phosphorus feed additive (manufacturer: Yuqiyangyang, brand: Subu 100).

[0052] The preparation example of the present invention is used for the harmless treatment of biogas residue.

[0053] Preparation Example 1

[0054] (1) After drying the biogas residue and poplar leaves separately, crush them into fragments with a particle size of less than 5 mm, mix them in a mass ratio of 7:3 (the total amount of biogas residue and poplar leaves is 5 kg), add water to make the moisture content 65 wt%, and carry out a 15-day aerobic composting pretreatment. During the composting process, turn the pile over every 3 days. When the moisture content is lower than 60%, add water to obtain the mixed base material.

[0055] (2) Place the mixed substrate into the breeding boxes to form an earthworm breeding bed. The breeding boxes are 30×20×12 (cm) plastic boxes with holes at the bottom, and the bottom is covered with a layer of 100-mesh mesh. Each box contains 1 kg of mixed substrate. Earthworms with reproductive rings (Eisenia fetida, initial average earthworm weight 220 mg) are then added for composting at a density of 0.2 kg / m³. 3 During earthworm composting, the ambient temperature was maintained at 25℃, and water was sprayed to keep the humidity at 70wt%. The compost was turned over every 3 days, and earthworms were collected from the compost samples after 45 days of composting.

[0056] In this preparation example, the survival rate of earthworms was 100%, and the average weight of the produced adult earthworms was 590.30 mg.

[0057] In this preparation example, the compost sample after vermicomposting had a carbon-to-nitrogen ratio of 11.96 and an E4 / E6 ratio of 4.73. This indicates that the compost sample has achieved good maturity and stability, making it a high-quality organic fertilizer.

[0058] Preparation Example 2

[0059] (1) After drying the biogas residue and poplar leaves separately, crush them into fragments with a particle size of less than 5 mm and mix them in a mass ratio of 7.5:2.5 (the total amount of biogas residue and poplar leaves is 5 kg). Add water to make the moisture content 70 wt% and carry out 20 days of aerobic composting pretreatment. Turn the pile over every 3 days during the composting process. When the moisture content is lower than 60%, add water to obtain the mixed base material.

[0060] (2) Place the mixed substrate into the breeding boxes to form an earthworm breeding bed. The breeding boxes are 30×20×12 (cm) plastic boxes with holes at the bottom, and the bottom is covered with a layer of 100-mesh mesh. Each box contains 1 kg of mixed substrate. Earthworms with reproductive rings (Eisenia fetida, initial average earthworm weight 231 mg) are then added for composting at a density of 0.25 kg / m³. 3 During earthworm composting, the ambient temperature was maintained at 25℃, and water was sprayed to keep the humidity at 65wt%. The compost was turned over every 3 days, and earthworms were collected from the compost samples after 45 days of composting.

[0061] In this preparation example, the survival rate of earthworms was 100%, and the average weight of the produced adult earthworms was 589.50 mg.

[0062] Preparation Example 3

[0063] This preparation example was carried out using a method similar to that of Preparation Example 1, except that the earthworm composting time was 20 days.

[0064] In this preparation example, the survival rate of earthworms was 100%, the initial average weight of earthworms was 210.5 mg, and the average weight of adult earthworms produced was 331.68 mg.

[0065] Preparation Example 4

[0066] This preparation example was carried out using a method similar to that of Preparation Example 1, except that the earthworm composting time was 90 days.

[0067] In this preparation example, the survival rate of earthworms was 100%, the initial average weight of earthworms was 229.8 mg, and the average weight of adult earthworms produced was 590.21 mg.

[0068] Comparative Preparation Example 1

[0069] This comparative preparation example was prepared using a method similar to that of Preparation Example 1, except that poplar leaves were not added and the total amount of biogas residue used was 5 kg.

[0070] In this comparative preparation, the survival rate of earthworms was 0% (earthworms escaped or died), the initial average weight of earthworms was 233.4 mg, and the average weight of adult earthworms produced was 0 mg.

[0071] Preparation of Comparative Example 2

[0072] This comparative preparation was carried out using a method similar to that of Preparation Example 1, except that poplar leaves were replaced with an equal mass of fruit peel residue (watermelon rind).

[0073] In this comparative preparation, the survival rate of earthworms was 0% (earthworms escaped or died), the initial average weight of earthworms was 235 mg, and the average weight of adult earthworms produced was 0 mg.

[0074] Comparative preparation example 3

[0075] This comparative preparation example was prepared using a method similar to that of Preparation Example 1, except that poplar leaves were replaced with an equal mass of paper scraps, the particle size of which was less than 5 mm.

[0076] In this comparative preparation, the survival rate of earthworms was 85%, the initial average weight of earthworms was 242 mg, and the average weight of adult earthworms produced was 368.88 mg.

[0077] Comparative preparation example 4

[0078] This comparative preparation example was prepared using a method similar to that of Preparation Example 1, except that poplar leaves were replaced with camphor leaves of equal mass, and the particle size of the camphor leaves was less than 5 mm.

[0079] In this comparative preparation, the survival rate of earthworms was 75%, the initial average weight of earthworms was 231.2 mg, and the average weight of adult earthworms produced was 448.3 mg.

[0080] Comparative preparation example 5

[0081] This comparative preparation example was prepared using a method similar to that of Preparation Example 1. The difference is that the total amount of biogas residue and poplar leaves was kept constant, and the mass ratio of biogas residue to poplar leaves was adjusted to 8.5:1.5.

[0082] In this comparative preparation, the survival rate of earthworms was 60%, the initial average weight of earthworms was 253 mg, and the average weight of adult earthworms produced was 332.2 mg.

[0083] Example 1

[0084] (1) The earthworms obtained after composting in the above example were temporarily kept in clean water for 10 hours to expel the contents of their digestive tract. Then, the washed earthworms were placed in a forced-air drying oven at 60°C and dried for 8 hours until constant weight was achieved. The dried earthworm blocks were crushed with a pulverizer and passed through a 100-mesh sieve. The material passing through the sieve was collected to obtain dark brown earthworm powder with a special fishy smell. The powder was sealed in a package and stored in a cool, dry place.

[0085] (2) Mix the earthworm powder obtained in step (1) with cogon grass, corn flour, rapeseed meal, wheat flour, calcium dihydrogen phosphate, salt, yellow mealworm powder, allicin, vitamins and minerals evenly to obtain earthworm compound feed.

[0086] (3) A lobster farming experiment was conducted using earthworm compound feed for 18 days, with 12 lobsters released into each group. In this example, the initial average weight of the lobsters was 13.19g.

[0087] (4) The daily feeding amount should be controlled at about 3% of the shrimp's body weight, and feeding should be done at 10 am and 6 pm.

[0088] (5) During the normal feeding period, turn on the oxygenation equipment every day to keep the dissolved oxygen in the water above 5 mg / L. Depending on the water color and other water quality conditions, sprinkle vitamin C once every 7 to 10 days to adjust the water quality.

[0089] Unless otherwise specified, the other embodiments are carried out with reference to the method of Embodiment 1. The difference is that the types and amounts of raw materials used in each embodiment are different, as detailed in Table 1.

[0090]

[0091] Comparative Example 1

[0092] This comparative example was conducted using a method similar to that of Example 1, except that earthworm powder was replaced with an equal mass of soybean meal.

[0093] Comparative Example 2

[0094] This comparative example was conducted using a method similar to that of Example 1, except that the type of earthworm remained the same, and the amount of earthworm powder was adjusted to 45g and the amount of soybean meal was adjusted to 135g.

[0095] Comparative Example 3

[0096] This comparative example was conducted using a method similar to that of Example 1, except that the type of earthworm remained the same, and the amount of earthworm powder and soybean meal was adjusted to 90g.

[0097] Comparative Example 4

[0098] This comparative example was conducted using a method similar to that of Example 1, except that the type of earthworm remained the same, the amount of earthworm powder was adjusted to 135g, and the amount of soybean meal was adjusted to 45g.

[0099] Comparative Example 5

[0100] This comparative example was conducted using a method similar to that of Example 1, except that the amount of Miscanthus sinensis was adjusted to 0g.

[0101] Test Case A

[0102] The pH value, total organic carbon (TOC), total nitrogen (TN), carbon-to-nitrogen ratio (C / N), organic matter (OM), and E4 / E6 of the mixture obtained by mixing biogas residue and poplar leaves in each preparation example (sample before aerobic composting) were tested. The main results are shown in Table 2.

[0103] The pH value of the sample aqueous suspension (1:10, w / v) was measured using a glass electrode pH meter.

[0104] The total organic carbon (TOC) content was determined using the potassium dichromate external heating method.

[0105] Total nitrogen (TN) content was determined using a Kjeldahl nitrogen analyzer (SONNEN, K06A, Shanghai).

[0106] The organic matter (OM) content was determined by the loss on ignition method, which involves calcining the sample at 550°C for 8 hours.

[0107] E4 / E6 ratio determination method: The mixture (dry matter) obtained by mixing biogas residue and poplar leaves in the preparation example was mixed with deionized water at a ratio of 1:10 (W(g): V(mL)). The mixture was extracted at room temperature with horizontal shaking at 200 rpm for 1 hour. Then, it was centrifuged at 10,000 rpm for 5 minutes, followed by filtration of the resulting mixture. The absorbance of the filtrate at 465 and 665 nm was measured using a UV-5200 UV-Vis spectrophotometer, and the E4 / E6 ratio was calculated accordingly.

[0108]

[0109] Table 2 shows that before aerobic composting, the mixture of biogas residue and poplar leaves had the richest organic matter content, and the pH and C / N ratio were suitable for earthworm growth. Comparative Preparations 1 and 3 had low organic matter content, and Comparative Preparation 2 had an excessively high pH, ​​both unsuitable for earthworm growth. In Preparation 4, the C / N ratio < 20 was not the optimal value for earthworm growth.

[0110] Test Case B

[0111] The protein, fat, and ash content of the adult earthworms prepared in the above preparation example were tested, and the specific results are shown in Table 3.

[0112] Sample preparation: The earthworms obtained after composting in the above examples were temporarily kept in clean water for 10 hours to expel their digestive contents. Then, the washed earthworms were placed in a 60℃ forced-air drying oven and dried for 8 hours until constant weight. The dried earthworm blocks were then crushed using a pulverizer and passed through a 100-mesh sieve. The sieve residue was collected to obtain dark brown earthworm powder with a distinctive fishy odor. The protein, fat, and ash content of the earthworm powder were tested using the Kjeldahl method, Soxhlet extraction, and calcination method.

[0113]

[0114] Test Case C

[0115] The breeding results in the above examples were tested. The test items were initial average weight, final weight, weight gain rate, specific growth rate, feed conversion ratio and survival rate. The specific results are shown in Table 4.

[0116] The following formulas are used to calculate the relevant indicators of growth performance and reproductive performance.

[0117] Weight gain rate = 100 × (Wt - W0) / W0;

[0118] Survival rate = 100 × Nt / N0;

[0119] Specific growth rate = (lnWt - lnW0) / t × 100;

[0120] Feed conversion ratio = Wf / (WtNt - W0N0).

[0121] In the formula, Nt is the final number of tails; N0 is the initial number of tails; Wt is the final body mass (g); W0 is the initial body mass (g); t is the number of experimental days (d); and Wf is the total weight of feed fed in each breeding box (g).

[0122]

[0123] As can be seen from the results in Table 4, the compound feed provided by the present invention can improve the growth performance and feed utilization of lobsters, improve the nutritional content of lobsters, and the effect is more obvious as the proportion of earthworm powder added increases.

[0124] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for harmlessly treating biogas residue and poplar leaves using earthworms, characterized in that: The method includes: (1) Mix biogas residue and poplar leaves and then perform aerobic composting to obtain a mixed substrate; (2) Earthworms are placed in a mixed substrate for earthworm composting to obtain composted earthworms; Based on the total amount of biogas residue and poplar leaves used, the amount of biogas residue used is 60-80 wt%, and the amount of poplar leaves used is 20-40 wt%.

2. The method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1, characterized in that: Biogas residue is the solid waste remaining after anaerobic fermentation to produce biogas in a fermentation plant; And / or, the particle size of biogas residue and poplar leaves is independently <5 mm.

3. A method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1 or 2, characterized in that: The biogas residue has a pH of 7-8, an organic carbon content of 270-320 g / kg, a total nitrogen content of 20-25 g / kg, a carbon-to-nitrogen ratio of 10-14, an organic matter content of 480-540 g / kg, and an E4 / E6 ratio of 2.8-3.

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4. A method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1 or 2, characterized in that: The conditions for aerobic composting are: moisture content of 60-70 wt% and time of 15-20 days.

5. A method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1 or 2, characterized in that: The stocking density of earthworms is 0.1~0.3 kg / m³. 3 .

6. A method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1 or 2, characterized in that: The conditions for vermicomposting are: temperature of 20-25℃, substrate moisture of 60-70wt%, turning the compost every 3-4 days, and composting time of 20-100 days.

7. A method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1 or 2, characterized in that: Based on the total amount of biogas residue and poplar leaves used, the amount of biogas residue used is 65-75 wt%, and the amount of poplar leaves used is 25-35 wt%.

8. A method for harmlessly treating biogas residue and poplar leaves using earthworms according to claim 1 or 2, characterized in that: The earthworm in question is the Eisenia fetidae.

9. A compound earthworm feed, characterized in that: The earthworm compound feed comprises the following components: 170-190 parts earthworm powder, 85-95 parts miscanthus, 30-40 parts corn flour, 50-60 parts rapeseed meal, 17-23 parts wheat flour, 3-5 parts calcium dihydrogen phosphate, 1.3-1.8 parts salt, 3-4 parts mealworm powder, 0.3-0.5 parts allicin, 2-3 parts vitamins, and 7-9 parts minerals. The earthworm powder is earthworm powder made from composted earthworms obtained by any one of claims 1 to 8 after drying and crushing.

10. The earthworm compound feed according to claim 9, characterized in that: The earthworm compound feed comprises the following components: 180 parts earthworm powder, 90 parts miscanthus, 36 parts corn flour, 54 parts rapeseed meal, 20 parts wheat flour, 4 parts calcium dihydrogen phosphate, 1.6 parts salt, 3.6 parts yellow mealworm powder, 0.4 parts allicin, 2.4 parts vitamins, and 8 parts minerals.

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