Method for preparing organic compound fertilizer by coupling hermetia illucens sand and chitosan
Chitosan and insect sand are synchronously extracted through black soldier fly aquaculture, and combined with high-temperature aerobic fermentation technology, functional organic composite fertilizers are prepared, solving the problems of organic waste treatment and high-value-added biological materials development in the existing technology, and achieving efficient and environmentally friendly green agricultural solutions.
Patent Information
- Application Number
- CN202510357596.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-25
- Publication Date
- 2025-05-13
AI Technical Summary
The prior art is difficult to effectively utilize organic waste, especially in the black soldier fly technology, and the functional coupling process of chitosan extraction and insect sand organic composite fertilizer is lacking, resulting in high chitosan price and insufficient fertilizer efficiency and disease resistance of insect sand.
Chitosan and insect sand were synchronized by black soldier flies breeding, and functional organic compound fertilizers were prepared by combining high-temperature aerobic fermentation process. The process includes the steps of black soldier fly larvae feeding, chitosan extraction, insect sand fermentation and organic fertilizer coupled with self-pull chitosan.
The simultaneous production of high-purity chitosan and functional insect sand organic composite fertilizer has been achieved, solving the problems of organic waste treatment and high-value-added biological materials development, improving the resource utilization efficiency of agricultural organic waste, and providing efficient and environmentally friendly green agricultural solutions.
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Figure CN119977700A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of biological resource utilization, and specifically relates to an integrated process for preparing functional organic fertilizer by synchronously extracting chitosan from organic waste as raw materials through black soldier fly breeding and coupling worm sand. The process is suitable for agricultural organic waste treatment, high value-added biomaterial development and green agriculture. Background Art
[0002] Organic waste such as straw, fruit and vegetable residues, expired agricultural organic waste and other agricultural organic wastes are difficult to handle due to mold or high moisture content, which leads to serious pollution and resource waste in traditional incineration and landfill methods. Therefore, it is necessary to develop a way to effectively utilize organic waste. Black soldier fly larvae feed on food waste, livestock and poultry manure, and agricultural organic waste, and can convert these substances into proteins, fats and other substances they need. Therefore, black soldier flies can be raised with organic waste to achieve the purpose of effectively treating organic waste. However, the current black soldier fly technology has certain limitations: the existing technology focuses on a single link, such as insect protein feed or insect sand composting, lacks the functional coupling process of chitosan extraction and insect sand organic compound fertilizer, and lacks the directional degradation technology of transformed waste; chitosan is expensive as an antibacterial material, and insect sand lacks fertilizer efficiency and disease resistance due to the lack of functional additives, so an integrated solution is urgently needed. Summary of the invention
[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for the full resource recovery of agricultural organic waste. To achieve the purpose of the present invention, the specific technical scheme is as follows: A method for preparing organic compound fertilizer by coupling black soldier fly worm sand with chitosan comprises the following steps: Step 1: Black soldier fly larvae breeding (1) 60% to 80% of the larvae that hatched for 5 to 8 days were transferred to the rearing and conversion system, and 20% to 40% were kept for breeding; (2) Agricultural organic waste is transported to the pretreatment system, crushed to a particle size of ≤3 mm, sterilized by steam (100°C, 30 min), and then adjusted to a moisture content of 70%-80% by a spray device; (3) The agricultural organic waste with adjusted moisture content enters the feeding and conversion system as feed for black soldier flies. The larvae are fed at a density of 6-8kg / m², a temperature of 30±2℃, and a humidity of 65-75%; the feeding frequency is 2-3 times a day, and the feeding amount is 12-15kg / m² each time; after 15-20 days of feeding, the insect sand and the insect body are separated.
[0004] Step 2: Extracting chitosan from black soldier flies (1) Inactivating the black soldier fly bodies obtained by breeding and separation, and drying them to a moisture content of 5-15%; (2) The dried black soldier flies are placed in a formic acid solution with a mass fraction of 10-15% formic acid for 2-4 hours at a temperature of 40-60°C, then washed with water until neutral, and dried to obtain sample A; (3) Sample A was added into a 30-60% mass fraction NaOH solution, soaked for 4-6 hours at a temperature of 80-90°C, and then washed with water until neutral; (4) Repeat steps (2) and (3) several times, and then dry the filtrate to obtain chitosan; the chitosan residue is kept for later use.
[0005] Step 3: High temperature aerobic fermentation of black soldier fly sand Formula design: Thoroughly mix worm sand and chitosan residue in a weight ratio of 60-80:20-30, adjust the C / N ratio to 28-36 with a certain amount of agricultural organic waste, adjust the moisture content to 55%-75%, and adjust the pH to 5.5-7.5, and finally add 0.1-0.3wt% Bacillus subtilis.
[0006] Fermentation process: High-temperature aerobic composting is an organic waste treatment process that uses aerobic microorganisms as the core and combines nano-film covering technology. The principle is to convert organic matter into humus through the oxidation and decomposition of microorganisms. During the process, the temperature of the pile can reach 55-75°C, effectively killing pathogens and weed seeds, while reducing odor emissions. According to the formula design, the material is subjected to high-temperature aerobic film composting. The composting cycle is 20-25 days, and the frequency of turning the pile is once every 3-5 days.
[0007] Step 4: Organic fertilizer coupled with self-extracted chitosan (1) Chitosan-worm sand synergistic granulation Preparation of composite adhesive: dissolve the chitosan extracted in the second step in 2% citric acid solution (mass ratio 1:50-70) to prepare chitosan glue solution, and premix the chitosan glue solution with organic fertilizer fermented from insect sand in a volume ratio of 1:9-11 to form a biological adhesive system.
[0008] Low-temperature extrusion molding: Use a two-stage granulator (first-stage temperature 45-55℃ / second-stage temperature 65-75℃) to extrude the mixture into spherical granular organic fertilizer with a diameter of 3-5mm. Chitosan forms a microporous film (pore size 50-100nm) on the surface of the particles, and the particle compressive strength is ≥30N.
[0009] (2) Granular organic fertilizer coupled with slow-release coating layer Preparation of coating solution: The chitosan extracted in the second step is dissolved in 0.5-1.5% acetic acid solution to prepare 2-5% basic mother solution, and then the coating solution is formed by cross-linking with 0.5-0.8% trisodium citrate and high-pressure homogenization (20MPa).
[0010] Fluidized bed dynamic coating: Under the condition of particle temperature of 60℃, 3-5 layers of coating liquid are sprayed alternately on the organic fertilizer at an air flow rate of 2-5m³ / min. The thickness of each layer is about 20-30μm. The layer-by-layer spraying is conducive to the absorption of coating liquid by the granular organic fertilizer, so that the sustained release effect of the organic fertilizer is optimal when used.
[0011] The beneficial effect of the present invention is that high-purity chitosan and functional insect sand organic compound fertilizer are simultaneously produced through black soldier fly breeding, thereby realizing a closed loop of "waste-high-value materials-green agriculture". BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 It is the overall flow chart of the present invention; Figure 2 The infrared spectrum (FTIR) of chitosan sample extracted from black soldier fly; Figure 3 This is the X-ray diffraction (XRD) pattern of the chitosan sample extracted from black soldier flies. DETAILED DESCRIPTION
[0013] Example 1 (taking moldy wheat bran as an example) H1: Black soldier fly larvae rearing process: (1) 70% of the 5-day-old larvae are transferred to the rearing and transformation system, and 20-40% are kept for breeding; (2) The moldy wheat bran is transported to the pretreatment system, crushed to a particle size of ≤3 mm, sterilized by steam (100°C, 30 min), and then adjusted to a moisture content of 70%-80% by a spray device; (3) The moldy wheat bran with adjusted moisture content enters the feeding and conversion system as feed for black soldier flies. The larvae are fed at a density of 6kg / m², a temperature of 30±2℃, and a humidity of 65-75%; the feeding frequency is 2-3 times a day, and the feeding amount each time is 12-15kg / m². After 15 days of feeding, the insect sand and the insect body are separated.
[0014] H2: Process of extracting chitosan from black soldier flies: (1) Inactivating the black soldier fly bodies obtained by breeding and separation, and drying them to a moisture content of 5-15%; (2) The dried black soldier flies are placed in a formic acid solution with a mass fraction of 10-15% formic acid for 2-4 hours at a temperature of 40-60°C, then washed with water until neutral, and dried to obtain sample A; (3) Sample A was added into a 30-60% mass fraction NaOH solution, soaked for 4-6 hours at a temperature of 80-90°C, and then washed with water until neutral; (4) Repeat steps (2) and (3) several times, and then dry to obtain the chitosan sample.
[0015] Depend on Figure 2 It can be seen that the extracted chitosan is characterized by FTIR spectrum at 4000cm -1 -500cm -1 The characteristic peaks of commercial chitosan structures appeared in the range. The changes in the extracted chitosan crystal structure can be analyzed by X-ray diffraction. The crystallinity can reflect the compatibility between molecules. The crystallinity also affects the mechanical properties, transparency and other related properties of the composite material. Figure 3 It can be seen that the extracted chitosan has three diffraction peaks at 2θ≈9.4°, 19.3° and 26.2°, which are typical semi-crystalline polysaccharide structural characteristics. In summary, the extracted chitosan meets the characteristics of commercial chitosan.
[0016] H3: High temperature aerobic fermentation process of black soldier fly sand: Formula design: Thoroughly mix insect sand (70%) and chitosan residue (30%), use a certain amount of moldy wheat bran to adjust the C / N ratio to 28-36, the moisture content to 55%-75%, the pH to 5.5-7.5, and finally add 0.2% Bacillus subtilis.
[0017] Fermentation process: High-temperature aerobic composting is an organic waste treatment process that uses aerobic microorganisms as the core and combines nano-film covering technology. The principle is to convert organic matter into humus through the oxidation and decomposition of microorganisms. During the process, the temperature of the pile can reach 55-75°C, effectively killing pathogens and weed seeds, while reducing odor emissions. According to the formula design, the material is subjected to high-temperature aerobic film composting. The composting cycle is 20-25 days, and the frequency of turning the pile is once every 3-5 days.
[0018] H4: Organic fertilizer coupled with self-extraction chitosan process: (1) Chitosan-worm sand synergistic granulation ① Preparation of composite adhesive: The chitosan extracted in step H2 is dissolved in 2% citric acid solution (mass ratio 1:50-70) to prepare chitosan glue, which is premixed with organic fertilizer fermented from insect sand at a volume ratio of 1:10 to form a biological adhesive system.
[0019] ② Low-temperature extrusion molding: Use a two-stage granulator (first-stage temperature 45-55℃ / second-stage temperature 65-75℃) to extrude the mixture into spherical particles with a diameter of 3-5mm. Chitosan forms a microporous film on the surface of the particles, and the compressive strength of the particles is ≥30N.
[0020] (2) Granular organic fertilizer coupled with slow-release coating layer ① Preparation of coating solution: The chitosan extracted in step H2 is dissolved in 1% acetic acid solution to prepare a 2-5% basic mother solution, and then the coating solution is formed by cross-linking with 0.5-0.8% trisodium citrate and high-pressure homogenization (20MPa).
[0021] ② Fluidized bed dynamic coating: When the particle temperature is 60℃, the coating liquid is sprayed at an air flow rate of 2-5m³ / min (3-5 layers are sprayed alternately), and the thickness of each layer is controlled at 20-30μm.
[0022] The green composite organic fertilizer prepared by the process of organic fertilizer coupling self-extraction chitosan has its component contents shown in Table 1 and its heavy metal content shown in Table 2.
[0023] Table 1 Index parameters of green composite organic fertilizer obtained by coupling organic fertilizer fermented from insect sand with self-extracted chitosan Table 2 Heavy metal content of green composite organic fertilizer prepared by coupling organic fertilizer fermented from insect sand with self-extracted chitosan It can be seen from Table 1 and Table 2 that the various technical indicators and heavy metal indicators of the green composite organic fertilizer prepared by the example of the present invention meet the corresponding regulations. For the convenience of illustrating the present invention, pakchoi seeds are selected as the cultivar, and seeds of uniform size, undamaged and healthy are selected for planting. The green compound organic fertilizer prepared by the experimental example scheme in Example 1 is selected and added to the soil at 2.5% and 5% of the mass of the soil. Purple acidic soil with a pH of 5.68 is selected as the test soil. Mix it with the soil in proportion, and use conventional compound fertilizer and organic fertilizer prepared by H3 (uncoupled chitosan) as controls. Three trays are used for each treatment, and 15 seeds are sown in each tray. After 15 days, 5 plants are planted, and water management is carried out every day to maintain the soil moisture content at 60%, and the growth of plants is observed regularly. Harvest and detect the growth of plants 40 days after planting.
[0024] Table 3 Effects of different organic fertilizers on the growth of Chinese cabbage As shown in Table 3, at an application rate of 2.5%, the conventional compound fertilizer had a plant height of 15.22 cm, a maximum leaf width of 47.29 cm, a maximum leaf length of 72.83 cm, 5 leaves, and a fresh weight of 44.45 g; the plant height of the H3 organic fertilizer was slightly higher (16.43 cm), the number of leaves increased to 6, and the fresh weight was 46.64 g; and the green compound organic fertilizer of the present invention was superior to the former two in plant height (17.61 cm), leaf width (51.41 cm), leaf length (76.54 cm) and fresh weight (47.54 g). When the application rate was increased to 5%, the indicators of each treatment group generally increased. For example, the plant height of the conventional compound fertilizer increased to 17.54 cm, and the fresh weight of the H3 organic fertilizer reached 48.31 g. The performance of the organic fertilizer of the present invention was particularly outstanding: the plant height reached 19.89 cm, the leaf width was 56.21 cm, the leaf length was 84.62 cm, the number of leaves increased to 7, and the fresh weight was 60.58 g, which was significantly higher than other groups. The data showed that the increase in application rate had a positive effect on the growth of Chinese cabbage, and the green compound organic fertilizer of the present invention had obvious advantages in promoting plant development, leaf expansion and yield improvement, especially at a 5% application rate, the comprehensive performance was the best.
[0025] Example 3 This example aims to verify the synergistic effect of the application of the green compound organic fertilizer of the present invention on wheat yield. Three treatment groups were set up in the experiment: (1) conventional compound fertilizer control; (2) organic fertilizer prepared by H3 (uncoupled chitosan); (3) green compound organic fertilizer of the present invention. A randomized block design was adopted, each treatment was repeated 3 times, and standardized field management was carried out under the same application rate, soil and climate conditions.
[0026] Table 4 Effects of different organic fertilizers on wheat yield As shown in Table 4, under the same application amount (50kg / mu) and standardized management conditions, the three organic fertilizer treatment groups have significant differences in the effect of increasing wheat yield. The yield per mu of the conventional compound fertilizer control group is 448kg; the yield per mu of the organic fertilizer (uncoupled chitosan) prepared in the third step is 483kg, an increase of 35kg (an increase of 7.81%) compared with the control group; and the yield per mu of the green compound organic fertilizer of the present invention reaches 504kg, an increase of 56kg (an increase of 12.5%) compared with the control group, and the increase is significantly higher than that of the organic fertilizer (uncoupled chitosan) prepared in the third step. The results clearly show that the green compound organic fertilizer of the present invention has obvious advantages in increasing wheat yield, further confirming the scientific nature and practical application value of its green compound formula.
[0027] Example 4 In order to facilitate the description of the effect of the thickness of the granular organic fertilizer coupled slow-release coating layer on plant growth in the present invention, the coating thickness was changed by adjusting the number of coating liquid spraying times in step 2 of the granular organic fertilizer coupled slow-release coating layer in the process of H4 organic fertilizer coupled self-extracted chitosan in Example 1. Keeping other preparation process parameters unchanged, the effect of coating layer thickness regulation on plant growth was explored.
[0028] Select pakchoi seeds as the cultivar, and select seeds of uniform size, undamaged and healthy for planting. Select the green compound organic fertilizer prepared by changing the number of times the coating liquid is sprayed in the experimental example scheme in Example 1, and add it to the soil at 2.5% and 5% of the mass of the soil. The test soil is purple acidic soil with a pH of 5.68. Mix it with the soil in proportion, use conventional compound fertilizer as a control, treat 3 trays for each treatment, and sow 15 seeds in each tray. After 15 days, plant 5 plants, manage water every day, keep the soil moisture content at 60%, and observe the growth of plants regularly. Harvest and test the growth of plants 40 days after planting.
[0029] Table 5 Effect of application of organic fertilizer prepared by different coating liquid spraying times on the growth of Chinese cabbage As shown in Table 5, the plant height of conventional compound fertilizer (without coating liquid spraying) is 16.88cm, the maximum leaf width is 51.61cm, the maximum leaf length is 77.43cm, the number of leaves is 6, and the fresh weight is 48.32g; while the green compound organic fertilizer of the present invention is sprayed with coating liquid once, and all indicators are improved (plant height 17.42cm, leaf width 53.36cm, leaf length 81.01cm, fresh weight 52.69g), and as the number of spraying increases to 3 and 5 times, the growth effect is further optimized, the plant height reaches 18.32cm and 18.92cm respectively, and the leaf width, leaf length, number of leaves and fresh weight all show an increasing trend (the fresh weight is up to 61.24g when sprayed 3 times). Overall, it is shown that the present invention significantly improves the growth performance of Chinese cabbage by regulating the number of coating liquid spraying (i.e., coating layer thickness), especially when sprayed 3 times, the comprehensive effect is the best.
Claims
1. A method for preparing organic compound fertilizer by coupling black soldier fly worm litter with chitosan, characterized in that: The method comprises the following steps: The first step: separating the insect sand from the insect body of the cultivated black soldier fly; Step 2: Extracting Chitosan (1) Inactivate the insects and dry them to a moisture content of 5-15%; (2) The insect body is immersed in a formic acid solution with a mass fraction of 10-15% formic acid for 2-4 hours at a temperature of 40-60°C, then washed with water until neutral, and dried to obtain sample A; (3) Sample A was added into a 30-60% mass fraction NaOH solution, soaked for 4-6 hours at a temperature of 80-90°C, and then washed with water until neutral; (4) Drying the filtrate to obtain chitosan, and retaining the chitosan residue for later use; Step 3: High temperature aerobic fermentation of insect sand The worm sand and chitosan residue are fully mixed in a weight ratio of 60-80:20-30, and a certain amount of agricultural organic waste is used to adjust the C / N ratio to 28-36, the moisture content to 55%-75%, and the pH to 5.5-7.5, and finally 0.1-0.3wt% of Bacillus subtilis is added to perform high temperature aerobic fermentation to obtain organic fertilizer; Step 4: Organic fertilizer coupled with self-extracting chitosan (1) Chitosan-worm sand synergistic granulation Preparation of composite adhesive: dissolve the chitosan extracted in the second step in 2% citric acid solution at a mass ratio of 1:50-70 to prepare chitosan glue solution, and premix the chitosan glue solution with organic fertilizer fermented from insect sand at a volume ratio of 1:9-11 to form a biological adhesive system; Low temperature extrusion molding: the mixture is extruded into spherical granular organic fertilizer, chitosan forms a microporous membrane with a pore size of 50-100nm on the surface of the granules, and the granule compressive strength is ≥30N; (2) Granular organic fertilizer coupled with slow-release coating layer Preparation of coating solution: The chitosan extracted in the second step is dissolved in 0.5-1.5% acetic acid solution to prepare 2-5% basic mother solution, and then cross-linked with 0.5-0.8% trisodium citrate and homogenized under high pressure to form coating solution; Fluidized bed dynamic coating: Under the condition of particle temperature of 60°C, 3-5 layers of coating liquid are sprayed alternately at an air flow rate of 2-5m³ / min to obtain the organic compound fertilizer.
2. The method for preparing organic compound fertilizer by coupling black soldier fly worm sand and chitosan as claimed in claim 1, characterized in that: The first step of the black soldier fly cultivation method includes: (1) 60% to 80% of the larvae that have hatched for 5 to 8 days are transferred to a breeding and transformation system for further cultivation into black soldier flies, and 20% to 40% are kept for breeding; (2) The organic waste is transported to the pretreatment system, crushed to a particle size of ≤3 mm, sterilized with steam, and then adjusted to a moisture content of 70-80% through a spray device; (3) The organic waste with adjusted moisture content enters the breeding and conversion system as feed for cultivating black soldier flies; the larvae are reared at a density of 6-8kg / m², the temperature is 30±2℃, and the humidity is 65-75%; the feeding frequency is 2-3 times a day, and the feeding amount each time is 12-15kg / m²; after 15-20 days of rearing, the worm sand and the worm body are separated.
3. The method for preparing organic compound fertilizer by coupling black soldier fly worm sand and chitosan as claimed in claim 1, characterized in that: In the fourth step of low-temperature extrusion molding, a two-stage granulator is used to extrude the mixture into spherical particles with a diameter of 3-5 mm. The first-stage temperature is 45-55°C, the second-stage temperature is 65-75°C, and chitosan forms a microporous membrane with a pore size of 50-100 nm on the surface of the particles. The particle compressive strength is ≥30N.
4. The method for preparing organic compound fertilizer by coupling black soldier fly worm sand and chitosan as claimed in claim 1, characterized in that: In the fourth step of preparing the coating solution, the chitosan extracted in the second step is dissolved in 1% acetic acid solution to prepare a basic mother solution.