Hermetia illucens sand staged matrix treatment method based on special microbial agent and application of hermetia illucens sand staged matrix treatment method

Abstract

The invention relates to the technical field of organic solid waste resource utilization and microorganisms, and discloses a hermetia illucens sand staged matrix treatment method based on a special microbial agent and application of the hermetia illucens sand staged matrix treatment method. According to the method, hermetia illucens sand serves as a main treatment object, after the carbon nitrogen ratio and the water content are regulated and controlled, a special complex microbial inoculant composed of at least two microorganisms of bacillus, lactobacillus and azotobacter is inoculated, and under the condition that a continuous forced aeration device is not arranged, the hermetia illucens sand is subjected to aeration treatment for 20-30 min, and the hermetia illucens sand is obtained. The treatment process is divided into a microbial community construction stage and a low-disturbance stable transformation stage, and matrix treatment is completed through staged stirring regulation and control. According to the method, a microbial community establishment state is taken as a stage switching basis, high-frequency mechanical disturbance and continuous oxygen supply requirements are reduced, and conversion and humification of organic matters in the hermetia illucens sand and nitrogen stabilization are realized. And the obtained matrix product is stable in structure and relatively high in decomposition degree, and can be used for preparing a seedling substrate, an organic fertilizer or a soil conditioner.

Description

Technical Field

[0001] This invention relates to the fields of organic solid waste resource utilization and microbial technology, specifically to a method for staged matrix regulation of black soldier fly sand based on a special composite microbial agent, and in particular, a method for stabilizing and humifying black soldier fly sand through staged mixing and regulation. Background Technology

[0002] Black soldier fly sand is composed of intestinal metabolic residues, unused materials, and molted exoskeletons of black soldier fly larvae after they transform organic solid waste. Its main components are organic matter, lignocellulose (including cellulose, hemicellulose, and lignin), and chitin, and it also contains a small amount of inorganic mineral elements (nitrogen, phosphorus, and potassium), which have high resource utilization potential.

[0003] Black soldier fly larvae sand has a high organic matter content and strong nitrogen activity, and some organic components are in an unstable state. If applied directly to the soil without stabilization treatment, it can easily cause violent microbial metabolic reactions in a short period of time, leading to problems such as heat generation, ammonia volatilization, and salt accumulation, which will adversely affect crop growth and the soil environment. Therefore, stabilization and composting treatment is usually required before agricultural use.

[0004] Existing insect sand treatment processes largely draw on traditional aerobic composting techniques, promoting organic matter decomposition through continuous oxygen supply, high-frequency turning, and prolonged high-temperature stages. However, black soldier fly worm sand possesses material characteristics such as high chitin content, high soluble salt content, and significant fluctuations in the carbon-nitrogen ratio. This leads to common problems in the application of the aforementioned treatment methods, including long treatment cycles, high mechanical disturbance intensity, and high energy input requirements.

[0005] Traditional processing methods are highly dependent on continuous oxygen supply. In material systems such as insect sand with unstable pore structure and easy compaction, it is often difficult to establish a stable and efficient microbial metabolic system in a short period of time. This can easily lead to local anaerobic conditions, uneven fermentation, or increased nitrogen loss, thus limiting the improvement of processing efficiency and product quality.

[0006] Publication No. CN118851834A discloses a method for the resource utilization of black soldier fly frass. The method requires first mixing agricultural waste with black soldier fly frass, then adding high-temperature resistant compound microbial agent, biochemical potassium humate and urea, and placing it in a closed drum fermentation chamber for fermentation. Then, the fermented material is mixed with agricultural waste, and high-temperature resistant compound microbial agent, biochemical potassium humate and urea are added and mixed again. The mixture is then fermented in windrows. After the fermentation temperature initially exceeds 60°C, the pile is turned over for further fermentation. After the temperature is lowered to 60°C, a heavy metal stabilizer is added to prepare organic fertilizer. While this method can promote the decomposition of organic matter to some extent, the nitrogen treatment process requires the repeated addition of exogenous conditioners and chemical additives, including biochemical potassium humate and urea, to the materials. This not only increases the complexity of the treatment process but also raises the difficulty of material compatibility and dosage control. In addition, this method adopts a treatment mode that combines closed drum fermentation and windrow fermentation. During the fermentation process, a relatively high temperature needs to be maintained, which is highly dependent on equipment conditions and operation management. The overall mechanical disturbance intensity is high, and the energy input requirement is large, which is not conducive to reducing the operating cost of the treatment process. Furthermore, the cumulative use of salt-containing additives such as biochemical potassium humate in the fermentation system may increase the soluble salt content in the product to some extent. If not properly controlled, it can easily increase the substrate or soil salinity load, affecting crop root growth and the long-term stability of the soil ecological environment.

[0007] Publication No. CN119528614A discloses a method for composting black soldier fly frass. This method involves mixing black soldier fly frass with biological waste, adjusting the carbon-to-nitrogen ratio, spraying with a microbial compound agent, and then adding glucose, potassium dihydrogen phosphate, polysorbate, ferrous sulfate, manganese sulfate, and copper sulfate. After thorough mixing, the mixture is piled up, covered with an insulating film, and sealed to obtain preliminary compost. Subsequently, hollow bricks are laid on top for secondary composting. Although this method, by adding external carbon sources, inorganic salts, and trace elements, combined with a special pile structure design, can improve the microbial metabolic activity and the duration of the high-temperature phase during composting to some extent, its practical application still has certain shortcomings. First, this method requires the addition of glucose, potassium dihydrogen phosphate, polysorbate, and various metal salts to the system during composting to regulate microbial metabolism and the reaction environment of the compost pile. This results in a large variety of exogenous additives, complex addition steps, and high requirements for material compatibility and operational management, which is not conducive to process simplification and stable operation. Second, this method uses a compost pile construction method that combines multi-layer hollow brick paving with multiple turnings to improve aeration and extend the high-temperature stage. This method relies heavily on manual operation and physical construction, resulting in a complex processing flow and significant energy input. Furthermore, this method... The current treatment approach still relies on traditional aerobic composting, promoting organic matter decomposition by enhancing oxygen supply and extending the high-temperature period. However, this method has limited adaptability to the dense structure, tendency to clump, high chitin content, and high salinity of black soldier fly excrement, making it difficult to establish a stable and efficient metabolic system in a short period of time in practical applications. Furthermore, this method introduces large amounts of soluble inorganic salts and surfactants during composting. If not properly controlled, this may increase the risk of soluble salt or metal ion residues in the compost products, placing higher demands on the safety and ecological stability of subsequent application as a substrate or fertilizer. Therefore, this method still has room for improvement in reducing dependence on exogenous substances, minimizing energy input, and achieving rapid stabilization and substrate-based treatment of black soldier fly excrement.

[0008] Publication No. CN120025196A discloses a method for enhancing the humification and nitrogen fixation of anaerobic fermentation biogas residue and black soldier fly frass co-composting using exogenous biochemical additives. This method involves mixing anaerobic biogas residue and black soldier fly frass in a certain proportion and introducing lignocellulose-degrading enzymes or their coupled biochemical additives during the aerobic composting process to promote organic matter degradation and humification. However, this method still has certain limitations in practical applications. First, this method relies on the co-composting of anaerobic digested biogas residue and black soldier fly larvae excrement, making its raw material source highly dependent on specific scenarios. It requires a stable anaerobic fermentation system and is not suitable for the independent treatment of black soldier fly sand alone, thus limiting its application scope. Second, this method requires the addition of lignin-degrading enzymes or coupled biochemical additives during composting, resulting in a high dependence on exogenous enzymes and chemical additives. This not only increases the cost of treatment but also enhances the complexity of process operation and addition management. Third, this method still employs a fully aerobic composting process, requiring continuous aeration to maintain the complete heating, high-temperature, and maturation phases, making it highly dependent on the oxygen supply system and operational energy consumption. When processing dense, easily agglomerated insect excrement, high aeration rates and long treatment cycles are often required, which is not conducive to reducing energy input and operating costs. Furthermore, this method achieves humification and nitrogen fixation by enhancing high-temperature aerobic processes, and its effectiveness largely depends on the continuous maintenance of external oxygen supply and enzymatic reaction conditions. It does not adequately tap into the self-organized metabolic potential of the microbial community within the insect excrement system, making it difficult to achieve rapid stabilization under low-disturbance, low-energy conditions. Therefore, this method still has room for further optimization in reducing the use of exogenous enzymes and biochemical additives, reducing the need for continuous aeration and mechanical disturbance, and achieving matrix-based transformation of black soldier fly larvae sand materials tailored to their characteristics.

[0009] In summary, existing technologies for treating black soldier fly sand generally suffer from a high degree of dependence on continuous aeration, high-frequency mechanical disturbance, and exogenous chemical or biochemical additives. There is still room for improvement in reducing energy input, simplifying the process flow, and achieving rapid, stable, and efficient matrix conversion tailored to the material characteristics of black soldier fly sand.

[0010] Therefore, developing a method for rapid substrate treatment of black soldier fly sand using specialized microbial agents as the core and through staged regulation is of great value and significance for promotion. Summary of the Invention

[0011] To address the problems existing in the prior art, this invention provides a method for rapid substrate treatment of black soldier fly sand using a specialized microbial agent as the core and through staged regulation. By constructing a microbial agent system with directional microbial function and a substrate treatment process dominated by microbial self-organized metabolism, this method achieves rapid conversion of easily degradable organic matter in black soldier fly sand, stable regulation of nitrogen speciation, and simultaneous optimization of the substrate structure without the need for forced aeration units and by reducing overall mechanical disturbance through staged stirring and regulation. This results in efficient humification and nitrogen retention.

[0012] This invention addresses the material characteristics of black soldier fly sand, such as high chitin content, high nitrogen activity, dense structure, and poor air permeability. It constructs a treatment system that combines a specialized microbial agent with a phased, low-disturbance matrix formation process, achieving the stabilization and matrix transformation of black soldier fly sand without the need for continuous forced oxygen supply and high-frequency mechanical stirring.

[0013] The specialized composite microbial agent described in this invention is not limited to specific strain names or preservation numbers. Its key feature is that the agent can synergistically degrade structural organic matter, assimilate and transform organic nitrogen, and promote humification within the black soldier fly sand system, thereby forming a stable functional synergistic relationship with the staged treatment process. The strain combinations and their proportions listed in the specific embodiments are merely preferred examples for achieving the aforementioned functional synergy, and this invention is not limited to these specific strain combinations.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] A method for staged matrix treatment of black soldier fly larvae in sand based on a special microbial agent and its application, characterized in that:

[0016] S1: Raw Material Preparation and Basic Control

[0017] Black soldier fly sand is used as the main treatment material. The black soldier fly sand is derived from the residue of black soldier fly larvae transforming organic waste. Corn stalks are added as a conditioner as needed to improve the pore structure of the material, so that the carbon-nitrogen ratio of the mixture is adjusted to 20:1-30:1 and the moisture content is adjusted to 55%-65%.

[0018] S2: Inoculation with special microbial inoculants:

[0019] A special compound microbial agent is inoculated into the material described in S1. The agent is composed of microorganisms with functions of cellulose degradation, hemicellulose conversion, chitin degradation and nitrogen conversion regulation. The inoculation amount of the agent is 3%-8% of the dry weight of the material.

[0020] The special compound microbial agent contains at least two microorganisms selected from the genera Bacillus, Lactobacillus, and Azotobacter.

[0021] S3: Staged matrixing process initiation:

[0022] The inoculated material is loaded into the matrix reactor to start the matrix treatment process, which is divided into two continuous stages: matrix stage one and matrix stage two.

[0023] S4: Matrix Formation Stage 1

[0024] In the first stage of substrate formation, the main goal is to promote the rapid establishment and functional activation of the microbial community. Through relatively short-cycle turning and mixing operations, the special compound microbial agent is brought into full contact with the material to form a uniform reaction system. No continuous aeration device is set up in this stage, and the gas exchange inside the material mainly relies on natural pore diffusion.

[0025] S5: Matrix Formation Stage Two

[0026] After the microbial system is constructed, the second stage of substrate preparation begins. The frequency of stirring is reduced, and intermittent, low-frequency stirring operations are performed so that the further decomposition, humification, and nitrogen stabilization of organic matter mainly rely on the metabolism of the microorganisms themselves, rather than external mechanical or oxygen supply enhancement.

[0027] S6: Determination of Maturity

[0028] When the material temperature stabilizes, the ammonia odor significantly decreases, and the humification index reaches the preset threshold, the matrix formation process ends, and a stabilized black soldier fly sand matrix product is obtained for humification degree testing.

[0029] Unlike the stage division based on temperature succession or oxygen supply intensity regulation in the prior art, the staged matrix treatment described in this invention does not focus on maintaining high temperature or enhancing oxygen supply, but rather uses the state of microbial community construction as the basis for stage switching.

[0030] The first stage of substrate formation aims at the colonization and functional activation of microbial agents, and achieves full contact between microorganisms and black soldier fly sand structured organic matter through limited turning and mixing;

[0031] In the second stage of substrate formation, after the microbial system has been established stably, the intensity of physical disturbance is actively reduced, so that the further transformation and humification of organic matter mainly rely on the metabolism of the microorganisms themselves.

[0032] The completion of the matrix formation stage is determined by one of the following criteria: slow fluctuation of the pile temperature, significant reduction of ammonia odor, or a significant decrease in temperature rise after turning over.

[0033] Unlike existing aerobic composting methods, the method of this invention does not use a continuous forced aeration device during the substrate formation process, does not use an external heat source to maintain a high temperature stage, and does not require high-frequency turning operations throughout the entire process. It relies solely on the synergistic metabolic action established by the special microbial agent in the black soldier fly sand system to complete the organic matter conversion. Preferred technical solution

[0034] Those skilled in the art can implement the present invention by replacing specific strains with microorganisms having the same or equivalent functions without changing the functional units and their synergistic relationships.

[0035] Preferably, the special microbial agent is not limited to a specific combination of strains. The key is a combination of functional units that simultaneously possess chitin degradation, organic nitrogen assimilation and humification promotion functions. The following combination of strains is one preferred implementation.

[0036] Preferably, the special composite microbial agent described in the method of the present invention includes Bacillus subtilis and Bacillus licheniformis, which can promote the rapid degradation of cellulose during the black soldier fly sand substrate treatment process; Bacillus megaterium, which can promote the release of nutrients from the black soldier fly sand substrate and improve the substrate; Lactobacillus acidophilus, which can produce small molecule organic acids to neutralize alkaline substances such as ammonia in the pile, reduce the odor of the pile, and inhibit the generation of putrefactive bacteria; and Azotobacter chroococcum, which can supplement the nitrogen source of the material, promote the humification reaction, and improve the stability of the substrate material.

[0037] Preferably, the microorganisms are deposited at the China General Microbiological Culture Collection Center (CGMCC), with Bacillus subtilis deposited at CGMCC 1.1086, Bacillus licheniformis at CGMCC 1.10257, Bacillus megaterium at CGMCC 1.6721, Lactobacillus acidophilus at CGMCC 1.12735, and Azotobacter chrysogenum at CGMCC 1.5803.

[0038] Most preferably, the preparation method of the special compound microbial agent is as follows: each of the above-mentioned strains is cultured in a culture medium to obtain a viable count of not less than 1×10⁻⁶. 9Single bacterial suspensions of CFU / mL were prepared and then mixed in the following volume ratio: Bacillus subtilis single bacterial suspension: Bacillus licheniformis single bacterial suspension: Bacillus megaterium single bacterial suspension: Lactobacillus acidophilus single bacterial suspension: Azotobacter chrysogenum single bacterial suspension = (0.2-1.0):(0.2-0.8):(0.2-0.8):(0.2-0.8):(0.1-0.6); wherein the total viable count of the mixed bacterial suspension is not less than 5 × 10⁻⁶. 9 CFU / mL.

[0039] The particularly preferred mixing volume ratio is 0.25:0.2:0.2:0.2:0.15.

[0040] Preferably, the substrate reactor is an acrylic cylindrical container without a forced aeration unit;

[0041] Preferably, the "low disturbance" mentioned in this invention does not mean that no mechanical operation is performed at all, but rather that during the entire substrate formation cycle, no continuous aeration device is set up, and no continuous oxygen supply or high-frequency full-cycle turning is relied upon. Its energy consumption is mainly concentrated in the short-term start-up process of the first stage of substrate formation. Compared with the operation mode of traditional aerobic composting that requires multiple daily turnings and continuous forced aeration, the treatment state with significantly reduced turning frequency and aeration intervention adopted in this method refers to a significantly lower operation intensity than the multiple daily turnings performed by traditional aerobic composting to maintain high temperature.

[0042] Preferably, the duration of the first stage of matrix formation is 7-12 days, and the turning and mixing operation is used to improve the initial mixing uniformity of the materials, and its purpose is not to enhance oxygen supply.

[0043] Preferably, the mixing operation in the first stage of substrate formation is intermittent, with a frequency of 1-3 times per day, each lasting 10-30 minutes. This frequency range is intended to promote uniform contact between the inoculant and the material and the construction of the microbial system, rather than as a means of continuous oxygen supply.

[0044] Preferably, the mixing frequency in the second stage of substrate formation is no more than once every 48 hours, and no forced aeration unit is set up;

[0045] Preferably, during the matrix formation process, the temperature of the stack naturally rises under the action of microorganisms, without the need for an external heat source to maintain the high-temperature stage;

[0046] Preferably, the nitrogen loss rate in the matrix-modified product is no higher than 12%, indicating that the method has a strong nitrogen retention capacity;

[0047] Preferably, the mass ratio of humic acid to fulvic acid in the matrix-modified product is not less than 1.8, indicating that the product has high stability and matrix applicability. Beneficial effects

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] By combining specialized compound microbial agents with a phased treatment process, the stabilization of black soldier fly sand can be achieved without the need for a continuous aeration system, providing a treatment path that does not rely on continuous aeration and high-frequency mechanical turning.

[0050] By controlling the turning and mixing in stages, the high disturbance operation of the traditional composting process is reduced, and the adverse effects of traditional high-frequency turning on the dense structure of the sand and insects (such as aggravating compaction) are avoided.

[0051] The synergistic effect of specialized microbial agents and staged substrate-based operations improved the metabolic efficiency of microorganisms in high-chitin, high-salt insect sand systems.

[0052] This provides an alternative process route that differs from traditional high-temperature aerobic processes and is more adapted to the structural characteristics of insect sand, making it suitable for dense organic solid wastes such as black soldier fly larvae sand.

[0053] The matrix products obtained by the method of this invention have stable structures and low salt loads, and can be used as seedling substrates, organic fertilizers or soil conditioners.

[0054] The method of this invention eliminates the continuous forced aeration unit, shortens the duration of high-disturbance operation, and concentrates energy input on the microbial community building stage in the early stage of substrate formation. This transforms the treatment process from the traditional aerobic composting mode that relies on external engineering enhancement to a substrate transformation path dominated by microbial self-organized metabolism. From the perspective of process structure, this reduces the dependence on continuous oxygen supply and mechanical turning, and provides a new technical solution for achieving low-energy-consumption stabilization treatment of black soldier fly sand. Attached Figure Description

[0055] Figure 1 This is a schematic diagram illustrating the temperature change over time during the sand matrix formation process of black soldier fly larvae treated by the method of this invention.

[0056] Figure 2 A schematic diagram illustrating the changes in total nitrogen content and nitrogen loss rate during the sand matrix transformation process of black soldier fly larvae treated by the method of this invention.

[0057] Figure 3 A schematic diagram showing the change in the mass ratio of humic acid to fulvic acid in the matrix-modified product after the treatment by the method of the present invention.

[0058] Figure 4 A schematic diagram of the microbial changes in the matrix-modified products after the treatment by the method of the present invention. Detailed Implementation

[0059] The present invention will be described in detail below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0060] Example 1: A staged matrix treatment method for black soldier fly larvae in sand based on a specialized microbial agent.

[0061] Black soldier fly larvae sand was used as the raw material for treatment. The sand originated from the residue of organic waste after the biotransformation of organic waste by black soldier fly larvae. Corn stalk powder was used as a conditioner to perform basic adjustments on the black soldier fly larvae sand material, adjusting the carbon-to-nitrogen ratio of the mixture to 25:1 and the moisture content to 60%.

[0062] The treatment group and control group in Example 1 were set up as follows:

[0063] T1: 500g black soldier fly larvae sand + 192.8g corn stalk powder;

[0064] T2: 500g black soldier fly sand + 192.8g corn stalk powder + 5% (dry weight) special compound microbial agent.

[0065] The special compound microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Lactobacillus acidophilus and Azotobacter chrysogenum. Each strain works synergistically to degrade cellulose and hemicellulose, transform chitin, and regulate nitrogen.

[0066] After the materials were thoroughly mixed, they were loaded into the matrix reactor for processing. The entire test cycle was 42 days and was divided into matrix stage one and matrix stage two.

[0067] The first stage of substrate formation is the system construction and initial composting stage, lasting 12 days. During this stage, to promote sufficient contact between the inoculant and the material and the rapid establishment of the microbial community, the material is turned over once a day for 15 minutes each time. No continuous aeration device is installed during this stage; gas exchange in the pile mainly relies on the pore structure of the material itself.

[0068] The second stage of matrix formation is a low-disturbance, stable conversion stage that lasts for 30 days. During this stage, the stirring frequency is adjusted to once every 48 hours. Its purpose is solely to improve the material structure and prevent localized caking, and it is not used as a means to enhance oxygen supply.

[0069] During the substrate formation process, no continuous aeration device is installed, and no additional exogenous enzyme preparations or chemical additives are introduced. The temperature of the pile naturally increases under the action of microbial metabolism.

[0070] Example 2: Comparative verification of the method of the present invention in typical organic materials other than insect sand.

[0071] To verify whether the method of the present invention is specifically designed for the characteristics of black soldier fly sand materials, rather than a general treatment solution for general organic waste, a non-black soldier fly sand material system was set up as a control for matrix treatment experiments.

[0072] Simulated kitchen waste was used as a typical non-insect sand organic material, whose main components were easily degradable organic matter and contained virtually no chitin. Following the same carbon-nitrogen ratio and moisture content conditions as in Example 1, 500g of simulated kitchen waste was thoroughly mixed with 160g of corn stalk powder, and inoculated with the same special composite microbial agent as in Example 1 at 5% of the material's dry weight. The mixture was then processed in a substrate reactor.

[0073] Specifically, the treatment group and control group in Example 2 were set up as follows:

[0074] T3: 500g simulated kitchen kitchen + 160g corn stalk powder;

[0075] T4: 500g simulated kitchen equipment + 160g corn stalk powder + 5% (by dry weight) special compound microbial agent;

[0076] The initial matrix formation process was also divided into two stages: Stage 1 lasted 12 days and Stage 2 lasted 30 days. The stirring frequency for each stage was the same as in Example 1.

[0077] The turning and mixing operation in the first stage mentioned above is only used for material homogenization during the start-up phase. Its frequency and duration are significantly lower than the turning operation carried out in traditional aerobic composting to maintain high temperature and oxygen supply, and it does not constitute continuous mechanical disturbance.

[0078] Implementation results:

[0079] Temperature was monitored throughout the process in Examples 1 and 2, and the results are shown in [the table below]. Figure 1 After matrix formation, the total nitrogen content and Hughes ratio of the products from each treatment group were measured, and nitrogen loss was calculated. The results are shown in [Table missing]. Figures 2-3 .

[0080] In the first stage of substrate preparation, all treatment groups experienced a rapid temperature rise, indicating that microbial metabolic activity was rapidly initiated, with the T2 group having the highest temperature peak.

[0081] The final total nitrogen contents of the products from groups T1, T2, T3, and T4 after substrate treatment were 3.01%, 3.64%, 2.22%, and 2.39%, respectively, and the nitrogen loss rates were 26.56%, 11.43%, 53.89%, and 51.39%, respectively. This indicates that the addition of special compound microbial agents and the staged substrate treatment method can effectively reduce nitrogen loss during the treatment process and improve the agricultural value of the products.

[0082] The final Hughes ratios of the products from groups T1, T2, T3, and T4 after matrix treatment were 1.1, 2.03, 1.11, and 1.15, respectively. This indicates that under the special compound microbial agent and the staged matrix treatment method, the black soldier fly sand has a higher degree of decomposition and is more complete.

[0083] The excellent nitrogen fixation effect and high humification level achieved by group T2 in Example 1 are also a preliminary manifestation of the synergistic mechanism inferred above in the experiment. In particular, compared with group T1, the nitrogen loss rate was significantly reduced, which suggests the key role of *Lactobacillus acidophilus* and *Azotobacter chrysogenum* in the system. To obtain the best results, those skilled in the art can verify and optimize the ratio of each strain through conventional experiments based on the above principles. For example, a control group lacking one or more functional bacteria can be set up to confirm their necessity and optimal addition ratio under specific material and process conditions.

[0084] In Example 1, compared with Group T1, Group T2 achieved deep humification and low nitrogen loss under conditions of no continuous aeration and only limited turning in one stage, proving that the scheme is effective for black soldier fly sand.

[0085] In Example 2, the exact same process and microbial agent were applied to simulated kitchen waste with a simple composition. The degree of humification and nitrogen retention were lower than in the insect-sand system of Example 1. This indicates that the microbial agent combination described in this invention exhibits significantly lower humification and nitrogen retention in non-black soldier fly insect-sand material systems compared to the black soldier fly insect-sand system. This suggests that the microbial agent system has better adaptability under black soldier fly insect-sand material conditions, rather than being a conventional microbial agent combination applicable to various types of organic solid waste.

[0086] Existing technologies generally employ enhanced aeration and high-frequency turning to treat black soldier fly sand, but these methods often face challenges such as high energy consumption and the tendency for localized anaerobic conditions and significant nitrogen loss due to the dense material. This invention, however, overcomes the inherent limitations of traditional approaches when dealing with materials like black soldier fly sand by first inoculating them with a specialized microbial agent and then employing a phased, low-disturbance strategy. This provides a new and more adaptable technical path for their stabilization treatment.

[0087] The above embodiments are merely illustrative of the present invention. In practical applications, there is no need to limit oneself to them. Modifications in form and details can be made without departing from the concept of the present invention, and all of the above should fall within the protection scope of the present invention.

Claims

1. A method for staged matrix treatment of black soldier fly larvae in sand based on a special microbial agent and its application, characterized in that... Includes the following steps: S1: Raw material preparation and basic control: Black soldier fly sand is used as the main treatment material. The black soldier fly sand is derived from the residue of black soldier fly larvae transforming organic waste. Corn stalks are added as a conditioner as needed to improve the pore structure of the material, so that the carbon-nitrogen ratio of the mixture is adjusted to 20:1-30:1 and the moisture content is adjusted to 55%-65%. S2: Inoculation with special microbial inoculants: A special compound microbial agent is inoculated into the material described in S1. The agent includes at least two combinations of Bacillus, Lactobacillus, and Azotobacter. The inoculation amount of the agent is 3%-8% of the dry weight of the material. S3: Staged matrixing treatment: The inoculated material is placed in a substrate reactor. The substrate reactor does not have a forced aeration unit. Gas exchange in the pile is completed through diffusion through the material pores and the stirring process. The substrate treatment includes substrate stage one and substrate stage two in sequence. The first stage of substrate formation aims to establish and activate the microbial community. Through a limited number of turning operations, the inoculant and the material are brought into full contact and colonization is completed. The turning operation in this stage is aimed at achieving material homogenization and establishing the function of the inoculant, rather than as a means of enhancing oxygen supply. The first stage of substrate formation lasts for 7-12 days, and the frequency of the limited number of turning operations is 1-3 times per day. The second stage of substrate formation is a low-disturbance stable transformation stage. After the microbial community is stably established, the frequency of turning and mixing is reduced to allow the organic matter to be further transformed and humified, which is mainly completed by the metabolism of the microorganisms themselves. The frequency of turning and mixing is reduced to no more than once every 48 hours. S4: Evaluation of Product Maturity When at least one of the following occurs: the temperature change of the pile tends to stabilize, the ammonia smell is significantly reduced, or the temperature rise after turning is significantly reduced, the matrix treatment is ended, and a stable black soldier fly sand matrix product is obtained.

2. The method according to claim 1, characterized in that... The black soldier fly sand is derived from the residue of organic waste after the black soldier fly larvae have biotransformed it.

3. The method according to claim 1, characterized in that, The conditioning agent is selected from corn stalks, rice straw, sawdust, or any combination thereof.

4. The method according to claim 1, characterized in that, The specialized compound microbial agent possesses at least two of the following functions simultaneously: 1) Degradation function of cellulose and hemicellulose; 2) Chitin degradation or transformation function; 3) Organic nitrogen assimilation or nitrogen speciation regulation function; 4) Promotes humification. The special compound microbial agent contains at least one microorganism with chitin degradation or transformation function.

5. The method according to claim 1 or 4, characterized in that, The specific compound microbial agent contains at least two of the following: Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Lactobacillus acidophilus, and Azotobacter chroococcum.

6. The method according to claim 1, characterized in that, The duration of the first stage of matrix formation is 7-12 days.

7. The method according to claim 1 or 6, characterized in that, The mixing operation in the first stage of matrix formation is intermittent, with a mixing frequency of 1-3 times per day, and each mixing lasts for 10-30 minutes.

8. The method according to claim 1, characterized in that, In the second stage of matrix formation, the mixing frequency shall not exceed once every 48 hours.

9. The method according to claim 1, characterized in that, The matrix reactor does not have a continuous aeration device; gas exchange in the reactor core mainly relies on diffusion through the material pores.

10. The method according to claim 1, characterized in that, No external heating source is set up during the matrix treatment process; the temperature of the stack body naturally increases due to the metabolic activity of microorganisms.

11. The application of the black soldier fly sand-stage substrate treatment method according to any one of claims 1-10 in the preparation of seedling substrate, organic fertilizer or soil conditioner.

12. The application according to claim 11, characterized in that, The seedling substrate, organic fertilizer, or soil conditioner is a substrate product that has passed the decomposition evaluation.

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