A method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae and the resulting organic fertilizer.

Abstract

This invention belongs to the technical field of kitchen waste treatment, specifically relating to a method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae, and the resulting organic fertilizer. The treatment steps include: crushing the kitchen waste into a slurry with a moisture content of 78%–83%; adding auxiliary materials to adjust the slurry moisture content to 65%–75%; then adding monosodium glutamate, L-arginine, and sugar, stirring evenly, and sterilizing; inoculating with a compound microbial agent for fermentation; placing the fermented material in a breeding box, spreading it to a thickness of 10cm–15cm, and inoculating the surface of the material with black soldier fly larvae to convert the fermented kitchen waste; after conversion, obtaining black soldier fly frass, and separating the black soldier fly bodies from the frass using a vibrating sieve. This method not only effectively promotes feeding by black soldier fly larvae, improves the conversion rate, and yields high-quality organic fertilizer, but also obtains insect protein feed, reduces environmental pollution, and enables the rational recycling of kitchen waste resources, showing good application prospects.

Description

Technical Field

[0001] This invention belongs to the technical field of kitchen waste treatment, and specifically discloses a method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae, and the organic fertilizer prepared therefrom. Background Technology

[0002] Food waste accounts for approximately 30%-50% of global solid waste. If not treated promptly, it easily produces foul odors, rots, mold, and breeds pathogenic microorganisms. The main treatment methods are landfill and organic fertilizer production. However, landfilling is costly and pollutes groundwater and the environment. Furthermore, food waste is high in oil and salt, presenting inherent drawbacks during treatment. When used as organic fertilizer in fields, the oil not only clogs soil pores, hindering root respiration and nutrient absorption, thus affecting plant growth, but the high salt content also has many negative effects on the soil, such as salinization and reduced arability. As people's awareness of environmental protection gradually increases, reducing environmental pollution while rationally utilizing resources has become a research hotspot.

[0003] Currently, the most researched technologies for the resource utilization of kitchen waste include anaerobic gasification, aerobic composting, and insect bioconversion. Significant progress has also been made in the research of insect bioconversion technology. For example, using black soldier flies for conversion can achieve two effects: firstly, it can digest kitchen waste and convert it into its own high-quality protein; secondly, its excrement is pure organic fertilizer free from heavy metal pollution and contaminating bacteria.

[0004] The literature "Nutritional Composition and Chemical Components Analysis of Black Soldier Fly Larvae from Food Waste Sources" scientifically evaluated the nutrition of black soldier fly larvae from food waste sources and the organic fertilizer from their excrement. Compared with soybean meal and fishmeal, black soldier fly larvae have a higher crude fat content and lower crude protein content. As a protein feed, black soldier flies need further defatting treatment. Moreover, the salt content in black soldier fly excrement is relatively high, and it must be treated before it can be used as organic fertilizer.

[0005] The literature "Study on the Influence of Fermentation on the Conversion of Kitchen Waste by Black Soldier Flies" investigated the effect of natural anaerobic fermentation of kitchen waste during storage on the conversion efficiency of kitchen waste by black soldier flies. Black soldier flies fed with kitchen waste that had been degreased and crushed and fermented for 2 days failed to grow normally. Black soldier flies fed with unfermented kitchen waste had the highest crude protein content, while those fed with kitchen waste that had been fermented for 6 days had the highest crude fat content. The nutrient content of the insect sand fermented for 2 days and 3 days met the standards of compound organic fertilizer, and the D5 group had the highest conversion rate of kitchen waste.

[0006] It is evident that the nutritional composition of black soldier fly larvae and their excrement is directly affected by the feeding substrate. Due to factors such as pH, moisture content, protein, heavy metals, and high oil and salt content in kitchen waste, current methods of feeding black soldier flies with this material require oil-water separation, desalination, or salt dilution. While directly feeding black soldier flies with organic waste can sustain their lives, it affects their palatability, thus impacting their conversion efficiency of kitchen waste, as well as the nutritional composition of the larvae and the resulting organic fertilizer. Therefore, research on black soldier fly feeding substrates is essential to further improve the conversion rate of kitchen waste and the efficiency of their excrement organic fertilizer. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae, and the resulting organic fertilizer. This invention effectively promotes feeding by black soldier fly larvae through the combined action of external microbial fermentation and additives. The exogenous microorganisms not only promote the decomposition of organic matter in kitchen waste but also improve the digestion and decomposition of organic matter by the black soldier fly larvae. The combined action of black soldier fly larvae and external microorganisms in treating kitchen waste not only increases the conversion rate of kitchen waste but also maintains a high-protein, low-fat nutritional profile for the growing black soldier fly larvae. The resulting larvae excrement is rich in organic matter and nutrients, with a low salt content, making it suitable as a high-quality organic fertilizer.

[0008] The primary objective of this invention is to provide a method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae.

[0009] The above objective is achieved through the following scheme: a method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae, comprising the following steps:

[0010] S1. Pre-treatment of kitchen waste: Sorting out inorganic impurities from kitchen waste, then crushing it into a slurry with a water content of 78% to 83%, adding auxiliary materials to adjust the slurry moisture to 65% to 75%, then adding additives, stirring evenly, sterilizing, and inoculating with compound microbial agents for fermentation.

[0011] The additives are monosodium glutamate, L-arginine, and white sugar;

[0012] S2. Inoculate with black soldier fly larvae: Place the fermented material from step S1 in a breeding box, spread it out to a thickness of 10-15cm, and inoculate the surface of the material with black soldier fly larvae to transform the fermented material.

[0013] S3. Insect-feed separation: After the conversion process is completed, the black soldier fly bodies and excrement are separated by vibrating screening, thus completing the treatment of kitchen waste.

[0014] Preferably, the auxiliary material in step S1 is selected from one or more of straw powder, wheat bran, straw ash, and rice bran.

[0015] Preferably, the amount of additive added in step S1 is 0.25 to 3.50% of the total slurry, wherein the ratio of monosodium glutamate: L-arginine: white sugar is 1 to 5: 1 to 3: 10 to 30, more preferably 2: 1.5: 18.

[0016] Monosodium glutamate (MSG) is the most widely used flavor enhancer both domestically and internationally, and its flavor-enhancing effect is usually achieved when coexisting with salt. This study found that combining MSG with L-arginine and sugar can improve the odor of fermented kitchen waste, increase the palatability of black soldier fly larvae to kitchen waste, and improve the conversion rate of kitchen waste.

[0017] Preferably, the inoculation amount of the compound microbial agent in step S1 is 2.4% to 5.6% of the slurry mass, and the compound microbial agent includes Bacillus, Aspergillus niger, and Saccharomyces cerevisiae.

[0018] The Bacillus strains used in the compound microbial agent of this invention are Bacillus subtilis, Bacillus amyloliquefaciens, and ATCCBAA-125, all of which are commercially available. The Bacillus strains are Bacillus sp. CICC 23870, Aspergillus niger CICC 2487, and Saccharomyces cerevisiae CICC 1044, all of which can be purchased from the China Industrial Microbial Culture Collection Center.

[0019] Preferably, the compound microbial agent in step S1 is a mixture of Bacillus subtilis, halophilic Bacillus ATCCBAA-125, Aspergillus niger CICC 2487, Bacillus spp. CICC 23870, and Saccharomyces cerevisiae CICC 1044 in a ratio of 1:2:2:2:1, with each microorganism having an effective viable count ≥3×10⁻⁶. 8 CFU / g.

[0020] Preferably, the fermentation temperature in step S1 is 28℃~35℃, the pH is 6.8~7.5, and the fermentation time is 24~72h.

[0021] Preferably, the black soldier fly larvae in step S2 are 2-3 days old, and the amount of larvae added during inoculation is 0.8-1.5 g / kg of material.

[0022] Preferably, the conversion in step S2 is carried out at a temperature of 28°C to 30°C and a relative humidity of 60% to 70%, and the conversion treatment lasts for 10 to 12 days.

[0023] This invention utilizes microbial fermentation and black soldier fly larvae to synergistically process kitchen waste. Since kitchen waste contains large amounts of protein, fat, cellulose, and starch, the fermented slurry is more readily consumed and digested by black soldier fly larvae. The Bacillus subtilis in the fermentation agent can produce various useful enzymes such as amylase and protease, and also possesses lipase activity. The produced lipase can degrade oily materials such as fats, greases, and cooking oils, while simultaneously promoting the normalization of the larval microbial flora and maintaining the larvae's health. Yeast is characterized by its resistance to osmotic pressure, acidity, and high metabolic efficiency, exhibiting a high capacity for cellulose degradation. The enzymes produced by Aspergillus niger have a certain ability to decompose proteins, vitamins, and starches, breaking them down into smaller molecules. This benefits the digestion and absorption of black soldier fly larvae and also provides glucose needed for fermentation by Saccharomyces cerevisiae and Bacillus subtilis. The synergistic effect of the several composite microbial agents selected in this invention significantly improves the nutritional level and digestibility of the fermented feed.

[0024] This invention involves inoculating the surface of fermented materials with black soldier fly larvae. The black soldier fly larvae are photophobic and will autonomously burrow into the material from top to bottom, which is more conducive to the disposal of kitchen waste and improves the waste conversion rate.

[0025] This invention not only processes kitchen waste but also yields a high-quality insect protein feed. The black soldier fly bodies separated in step S3 of the above method are dried to a moisture content of 10% to 15% to obtain the high-quality insect protein feed.

[0026] The present invention also provides an organic fertilizer, wherein the black soldier fly larvae excrement separated in step S3 of the above method can be directly used as a biological organic fertilizer.

[0027] Compared with the prior art, the superior effects of the present invention are mainly reflected in the following aspects:

[0028] 1. This invention uses microbial agents and black soldier fly larvae to treat kitchen waste, eliminating the need for oil-water separation and salt dilution pretreatment. The selected compound microbial agents can work synergistically under high oil and high salt conditions, and the fermentation metabolites can effectively degrade the large molecules such as proteins, oils, and cellulose in kitchen waste, thereby increasing the feeding amount and digestive capacity of black soldier fly larvae when transforming kitchen waste.

[0029] 2. This invention introduces additives such as monosodium glutamate, L-arginine, and white sugar that can attract black soldier fly larvae, which significantly improves the palatability of black soldier fly larvae to fermented kitchen waste, increases their feeding amount, and improves the conversion rate of kitchen waste.

[0030] 3. This invention uses fermented kitchen waste as feed to obtain black soldier fly larvae with high protein and low fat, which can be used as high-quality insect protein feed. At the same time, the produced insect excrement has a lower salt content and high organic matter and nutrient content, which can be used as organic fertilizer without further desalination.

[0031] 4. The method for treating kitchen waste by microorganisms in synergy with black soldier fly larvae provided by this invention not only achieves full recycling of kitchen waste resources with high conversion rate and low cost, but also obtains insect protein feed and organic fertilizer products, maximizing resource utilization and showing good application prospects. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified in the embodiments of the present invention, preparation shall be carried out under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products that can be purchased commercially.

[0034] The Bacillus strains used in the embodiments of this invention are Bacillus subtilis, Bacillus amyloliquefaciens, and ATCCBAA-125. Aspergillus oryzae can be commercially available. Bacillus sp. CICC23870, Aspergillus niger CICC 2487, Saccharomyces cerevisiae CICC 1044, and Lactobacillus plantarum CICC 21804 can all be purchased from the China Industrial Microbial Culture Collection Center.

[0035] In order to keep the content of various substances in kitchen waste at a basically the same level, the kitchen waste used in the embodiments and comparative examples of this invention is from the same batch. After the inorganic impurities are picked out and crushed, 200 kg of each batch is taken for different experimental conditions.

[0036] Example 1

[0037] A method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae includes the following steps:

[0038] (1) Pretreatment of kitchen waste: After collecting kitchen waste and removing large inorganic impurities, crush it and take 200 kg to make a slurry with a moisture content of 80%. Add straw powder and wheat bran to adjust the moisture content of the slurry to 68%. Then add 1.75% of the total slurry with additives (mixed according to the ratio of monosodium glutamate: L-arginine: white sugar of 2:1.5:18). Stir the mixture evenly and sterilize the material. Then inoculate 3.2% of the total slurry mass with compound microbial agent. The compound microbial agent is a mixture of salt-tolerant Bacillus (ATCCBAA-125): Aspergillus niger (CICC 2487): Bacillus spp. (CICC 23870): Saccharomyces cerevisiae (CICC 1044) in a ratio of 3:2:2:1. The effective viable count of each microorganism is ≥3×10 8 CFU / g, the inoculated compound bacteria are activated in advance, and the bacterial solution is sprayed once after each layer of material is added; after mixing, it is put into the fermentation tank and fermented for 60 hours at a constant temperature of 30℃ and pH 7.2.

[0039] (2) Inoculation with black soldier fly larvae: Take 100 kg of kitchen waste after fermentation in step S1, spread it in a breeding box with a thickness of 13 cm, and inoculate 3-day-old black soldier fly larvae on the surface of the fermented material. The amount of larvae added during inoculation is 1.0 g / kg of material. The fermented kitchen waste is then converted. During the conversion period, ventilation is carried out regularly, the pile is turned over, and the indoor temperature is maintained at about 28°C and the relative humidity is 65%RH. The conversion treatment is carried out for 10 days.

[0040] (3) Insect feed separation: After the conversion treatment is completed, the black soldier fly body and insect excrement are separated by vibrating sieve; the separated black soldier fly larvae are dried to a moisture content of 10% to 15% to obtain high-quality insect protein feed, and the separated insect excrement can be used as biological organic fertilizer.

[0041] Example 2

[0042] (1) Pretreatment of kitchen waste: After collecting kitchen waste and removing large inorganic impurities, crush it and take 200 kg to make a slurry with a moisture content of 80%. Add straw powder and wheat bran to adjust the moisture content of the slurry to 75%. Then add 0.4% of the total slurry with additives (in a ratio of monosodium glutamate: L-arginine: white sugar of 4:2:20). Stir the mixture evenly and sterilize the material. Then inoculate 2.4% of the total slurry mass with a compound microbial agent. The compound microbial agent is a mixture of halophilic Bacillus (ATCCBAA-125): Aspergillus niger (CICC 2487): Bacillus spp. (CICC 23870): Saccharomyces cerevisiae (CICC 1044) in a ratio of 3:2:2:1. The effective viable count of each microorganism is ≥3×10⁻⁶. 8 CFU / g, the inoculated compound bacteria are activated in advance, and the bacterial solution is sprayed once after each layer of material is added; after mixing, it is put into the fermentation tank and fermented at 32℃ and pH7.0 for 72 hours;

[0043] (2) Inoculation with black soldier fly larvae: Take 100 kg of kitchen waste after fermentation in step S1, spread it in a breeding box with a thickness of 15 cm, and inoculate 3-day-old black soldier fly larvae on the surface of the fermented material. The amount of larvae added during inoculation is 1.2 g / kg of material. The fermented kitchen waste is then converted. During the conversion period, ventilation is carried out regularly, the pile is turned over, and the indoor temperature is maintained at about 28°C and the relative humidity is 65%RH. The conversion treatment is carried out for 10 days.

[0044] (3) Insect feed separation: After the conversion treatment is completed, the black soldier fly body and insect excrement are separated by vibrating sieve. The separated black soldier fly larvae are dried to a moisture content of 10% to 15% to obtain high-quality insect protein feed. The separated insect excrement can be used as biological organic fertilizer.

[0045] Example 3

[0046] (1) Pretreatment of kitchen waste: After collecting kitchen waste and removing large inorganic impurities, crush it and take 200 kg to make a slurry with a moisture content of 80%. Add straw powder and wheat bran to adjust the moisture content of the slurry to 70%. Then add 3.0% of the total slurry with additives (mixed according to the ratio of monosodium glutamate: L-arginine: white sugar of 2:1.5:18). Stir the mixture evenly and sterilize the material. Then inoculate 4.0% of the total slurry mass with compound microbial agent. The compound microbial agent is Bacillus subtilis: halophilic Bacillus (ATCCBAA-125): Aspergillus niger (CICC 2487): Bacillus spp. (CICC 23870): Saccharomyces cerevisiae (CICC 1044) in a ratio of 1:2:2:2:1. The effective viable count of each microorganism is ≥3×10 8 CFU / g, the inoculated compound bacteria are activated in advance, and the bacterial solution is sprayed once after each layer of material is added; after mixing, it is put into the fermentation tank and fermented for 60 hours at 30℃ and pH 7.2.

[0047] (2) Inoculation with black soldier fly larvae: Take 100 kg of kitchen waste after fermentation in step S1, spread it in a breeding box with a thickness of 13 cm, and inoculate 3-day-old black soldier fly larvae on the surface of the fermented material. The amount of larvae added during inoculation is 1.0 g / kg of material. The fermented kitchen waste is then converted. During the conversion period, ventilation is carried out regularly, the pile is turned over, and the indoor temperature is maintained at about 28°C and the relative humidity is 65%RH. The conversion treatment is carried out for 10 days.

[0048] (3) Insect feed separation: After the conversion treatment is completed, the black soldier fly body and insect excrement are separated by vibrating sieve. The separated black soldier fly larvae are dried to a moisture content of 10% to 15% to obtain high-quality insect protein feed. The separated insect excrement can be used as biological organic fertilizer.

[0049] Example 4

[0050] (1) Pretreatment of kitchen waste: After collecting kitchen waste and removing large inorganic impurities, crush it and take 200 kg to make a slurry with a moisture content of 80%. Add straw powder and wheat bran to adjust the moisture content of the slurry to 65%. Then add 2.5% of the total slurry with additives (mixed according to the ratio of monosodium glutamate: L-arginine: white sugar in a ratio of 2:3:25). Stir the mixture evenly and sterilize the material. Then inoculate 5.6% of the total slurry mass with a compound microbial agent. The compound microbial agent is a mixture of Bacillus halophilus (ATCCBAA-125): Bacillus amyloliquefaciens: Aspergillus niger (CICC 2487): Bacillus spp. (CICC 23870): Saccharomyces cerevisiae (CICC 1044) in a ratio of 2:1:2:2:1. The effective viable count of each microorganism is ≥3×10⁻⁶. 8 CFU / g, the inoculated compound bacteria are activated in advance, and the bacterial solution is sprayed once after each layer of material is added; after mixing, it is put into the fermentation tank and fermented at 32℃ and pH7.0 for 48 hours;

[0051] (2) Inoculation with black soldier fly larvae: Take 100 kg of kitchen waste after fermentation in step S1, spread it in a breeding box with a thickness of 13 cm, and inoculate 3-day-old black soldier fly larvae on the surface of the fermented material. The amount of larvae added during inoculation is 0.8 g / kg of material. The fermented kitchen waste is then converted. During the conversion period, ventilation is carried out regularly, the pile is turned over, and the indoor temperature is maintained at about 28°C and the relative humidity is 65%RH. The conversion treatment is carried out for 10 days.

[0052] (3) Insect feed separation: After the conversion treatment is completed, the black soldier fly body and insect excrement are separated by vibrating sieve. The separated black soldier fly larvae are dried to a moisture content of 10% to 15% to obtain high-quality insect protein feed. The separated insect excrement can be used as biological organic fertilizer.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that in the fermentation inoculation of the compound microbial agent in the kitchen waste pretreatment step, Lactobacillus plantarum (CICC 21804) is used instead of Bacillus spp. (CICC 23870). The compound microbial agent is made by mixing halophilic Bacillus (ATCCBAA-125): Aspergillus niger (CICC 2487): Lactobacillus plantarum (CICC 21804): Saccharomyces cerevisiae (CICC 1044) in a ratio of 3:2:2:1. All other conditions and steps remain unchanged and will not be repeated here.

[0055] Comparative Example 2

[0056] The difference from Example 1 is that the compound microbial agent used for fermentation in the pretreatment step of kitchen waste is Aspergillus oryzae instead of Aspergillus niger. The compound microbial agent is a mixture of halophilic Bacillus (ATCCBAA-125): Aspergillus oryzae: Bacillus spp. (CICC23870): Saccharomyces cerevisiae (CICC 1044) in a ratio of 3:2:2:1. Other conditions and steps remain unchanged and will not be repeated here.

[0057] Comparative Example 3

[0058] The difference from Example 1 is that the additive introduced in the pretreatment step of kitchen waste does not contain L-arginine, and the ratio of monosodium glutamate to white sugar is 3.5:18. All other conditions and steps remain unchanged and will not be repeated here.

[0059] Comparative Example 4

[0060] The difference from Example 1 is that the additive introduced in the pretreatment step of kitchen waste is L-cysteine ​​instead of sodium glutamate. The additive is prepared in the ratio of L-cysteine:L-arginine:sugar of 2:1.5:18. All other conditions and steps remain unchanged and will not be repeated here.

[0061] Comparative Example 5

[0062] The difference from Example 1 is that the pretreatment step of kitchen waste does not involve fermentation. After adding the additive and stirring evenly, black soldier fly larvae are inoculated. All other conditions and steps remain unchanged and will not be repeated here.

[0063] Test methods and results analysis

[0064] Analysis of the transformation of kitchen waste in Experiment Example 1

[0065] Method for calculating the conversion rate of kitchen waste:

[0066] (1) Total weight gain of black soldier fly (kg) = A2 - A1,

[0067] A2 is the total dry weight of black soldier fly larvae after transformation, and A1 is the total dry weight of black soldier fly larvae before transformation;

[0068] (2) Kitchen waste reduction rate (%) = (B1-B2) / B1×100,

[0069] B1 is the total dry weight of kitchen waste before conversion, and B2 is the total dry weight of kitchen waste after conversion.

[0070] (3) Kitchen waste conversion rate (%) = (A2-A1) / (B1-B2)×100.

[0071] The calculation results are shown in Table 1.

[0072] Table 1

[0073]

[0074] As shown in Table 1, the method for treating kitchen waste in the embodiments of the present invention utilizes composite microbial degradation in conjunction with black soldier fly larvae treatment, eliminating the need for oil-water separation or dilution of kitchen waste. This not only increases the reduction rate of kitchen waste but also significantly improves the growth and development of black soldier fly larvae, resulting in a marked increase in larval weight gain. The feed conversion rate of fermented kitchen waste fed to black soldier fly larvae can reach over 25%.

[0075] Comparative Examples 1 and 2 altered the composition of the compound microbial agent used in the fermentation of kitchen waste, potentially leading to poor decomposition of large molecules such as oils and proteins in the kitchen waste. This resulted in reduced feeding of black soldier fly larvae on the fermented material and indigestion, thus lowering the conversion rate. This demonstrates that the compound microbial agents screened in this invention exhibit better synergistic effects. Comparative Examples 3 and 4 changed the types of additives. The reduction in kitchen waste indicates that the palatability and feeding amount of black soldier fly larvae on the kitchen waste were far less than in the Example 1 group, affecting their feeding efficiency and growth, and also significantly reducing the waste conversion rate. When Comparative Example 5, which did not undergo a fermentation step and was treated only with black soldier fly larvae, showed the lowest waste conversion efficiency.

[0076] Experiment Example 2: Nutritional Composition and Safety Analysis of Black Soldier Fly Larvae

[0077] Methods for determining the nutritional composition of black soldier fly larvae:

[0078] Five black soldier fly larvae were randomly selected from the breeding box for testing. The separated black soldier fly larvae were dried and crushed, and the contents of crude protein, crude fat and crude ash in the insect powder were measured and the average values ​​were calculated.

[0079] The crude protein content of black soldier fly larvae meal was tested according to the Kjeldahl method for the determination of crude protein in feed (GB / T 6432-2018); the crude ash content was tested according to the determination of crude ash in feed (GB / T 6438-2007); and the crude fat content was tested according to the determination of crude fat in feed (GB / T 6433-2006).

[0080] The test results are shown in Table 2.

[0081] Table 2

[0082]

[0083] As shown in Table 2, directly treating kitchen waste with black soldier fly larvae without fermentation promotes fat accumulation, resulting in a relatively high fat content in the larvae. Kitchen waste fermented using this invention, followed by inoculation with black soldier fly larvae for further transformation, further promotes insect protein accumulation, leading to a higher protein content and relatively lower fat content in the larvae, with little difference in crude ash content. Furthermore, the insect powder meets the requirements of the "Feed Hygiene Standard" (GB 13078-2017), with both heavy metal content and total bacterial count below the required limits. This makes it a healthier, high-protein, low-fat health product and a higher-quality insect protein feed.

[0084] Analysis of the composition and content of insect excrement in Experiment Example 2

[0085] Methods for detecting components in insect excrement:

[0086] The moisture content of the insect excrement in each example group was determined by drying in an oven at 105℃ and then weighing; the salt content was determined by GB / T 6439—2007 "Determination of water-soluble chlorides in feed"; the organic matter, total nutrient (N, P, K) content, and pH value were determined by the methods in "Organic Fertilizer" (NY 525—2021).

[0087] The measurement results are shown in Table 3.

[0088] Table 3

[0089]

[0090] The heavy metal content of the black soldier fly frass collected in the examples was tested. The limit requirements and testing methods were in accordance with "Organic Fertilizer" (NY 525-2021). All indicators were tested three times for each sample. The test results are shown in Table 4.

[0091] Table 4

[0092]

[0093] The results showed that the content of all chemical components in the insect excrement was within the requirements of the "Organic Fertilizer" (NY 525-2021) standard. The insect excrement treated with fermentation and black soldier fly larvae had higher organic matter and nutrient content, and the content of all heavy metal elements was far below the limits of the "Organic Fertilizer" (NY 525-2021) standard, superior to the insect excrement organic fertilizer obtained from the unfermented group. The study also found that the unfermented group had high salt content due to poor digestion and absorption by the black soldier fly larvae. Enrichment in this group might reduce the degradation efficiency of organic matter in the soil and fertilizer, as well as microbial respiration. Therefore, further desalination treatment is needed when using it as organic fertilizer. The treatment method in this embodiment of the invention may promote the overabsorption of inorganic salts by the black soldier fly larvae after fermentation, increasing the salt content of the insects and reducing the salt content of the produced insect excrement, making it safer and more feasible as organic fertilizer.

[0094] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for treating kitchen waste using microorganisms in conjunction with black soldier fly larvae, characterized in that, Includes the following steps: S1. Pre-treatment of kitchen waste: Sorting out inorganic impurities from kitchen waste eliminates the need for oil-water separation and salt dilution pre-treatment. The waste is then crushed into a slurry with a moisture content of 78%–83%. Additives are added to adjust the slurry moisture content to 65%–75%. After adding additives and mixing thoroughly, the mixture is sterilized and inoculated with a compound microbial agent for fermentation. The additives are monosodium glutamate, L-arginine, and white sugar. S2. Inoculation with black soldier fly larvae: Take the fermented material from step S1 and place it in the breeding box, spreading it out to a thickness of 10cm to 15cm. Inoculate the surface of the material with black soldier fly larvae to transform the fermented material. S3. Insect-feed separation: After the conversion process is completed, the black soldier fly bodies and excrement are separated by vibrating screening, thus completing the treatment of kitchen waste. The auxiliary material mentioned in step S1 is selected from one or more of straw powder, wheat bran, straw ash, and rice bran; The amount of additive added in step S1 is 0.25% to 3.50% of the total slurry, wherein the ratio of monosodium glutamate: L-arginine: white sugar is 1~5:1~3:10~30; The inoculation amount of the compound microbial agent in step S1 is 2.4% to 5.6% of the slurry mass; the compound microbial agent is a mixture of Bacillus subtilis, halophilic Bacillus ATCCBAA-125, Aspergillus niger CICC 2487, Bacillus spp. CICC 23870, and Saccharomyces cerevisiae CICC 1044 in a ratio of 1:2:2:2:1, with each strain having an effective viable count ≥3×10⁻⁶. 8 CFU / g; the fermentation temperature in step S1 is 28℃ ~ 35℃, the pH is 6.8 ~ 7.5, and the fermentation time is 24h ~ 72h.

2. The method according to claim 1, characterized in that, The black soldier fly larvae mentioned in step S2 are 2 to 3 days old, and the amount of black soldier fly larvae added during inoculation is 0.8 to 1.5 g / kg of material.

3. The method according to claim 1, characterized in that, The conversion process described in step S2 is carried out at a temperature of 28°C to 30°C and a relative humidity of 60% to 70%, and the conversion treatment lasts for 10 to 12 days.

Images