Method for biologically converting silkworm excrement waste by using hermetia illucens and application of product of method

Abstract

The invention discloses a method for biologically converting silkworm excrement waste by using hermetia illucens and application of a product of the method. The method comprises the following steps: breeding and domesticating hermetia illucens species, pretreating the silkworm excrement waste, performing bioconversion treatment, and separating and applying the treated product. The method has the advantages that (1) according to the method, the silkworm excrement waste is pretreated to adjust the moisture content of the silkworm excrement waste, so that normal growth and function exertion of the hermetia illucens in the substrate are guaranteed; (2) through the biotransformation effect of the hermetia illucens, organic substances in the silkworm excrement are efficiently utilized, and meanwhile, the dependence on chemical fertilizers is reduced. The high protein content of the hermetia illucens larvae makes the hermetia illucens larvae become high-quality feed resources and can be used for feeding fishes, poultry and the like, and the hermetia illucens adults can serve as animal protein sources. And (3) due to short treatment period and high conversion efficiency, the production cost can be reduced, and meanwhile, due to excellent product quality, higher market price can be obtained, so that good economic benefits are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of biological waste treatment, and relates to a harmless and large-scale treatment method, specifically a method for biologically transforming silkworm excrement waste using black soldier flies and application of the product thereof. Background Art

[0002] In agricultural production, silkworm excrement is an important organic waste, and its rational treatment is of great significance to the protection of the ecological environment and the effective utilization of resources. Silkworm excrement mainly comes from the breeding process of silkworm larvae. It is not only rich in nutrients, such as nitrogen, phosphorus, potassium, etc., but also contains a certain amount of organic matter and trace elements, which has a positive role in promoting soil improvement and crop growth.

[0003] Wheat bran is a byproduct of wheat processing. It is mainly composed of the outer cortex of the endosperm and is rich in nutrients such as dietary fiber, protein, B vitamins and minerals. In the agricultural field, wheat bran is not only a high-quality feed ingredient for feeding livestock and poultry, but also can be used as an organic fertilizer to improve soil structure and provide nutrients for plant growth. In addition, wheat bran is also widely used in bioenergy production, biodegradable material manufacturing and food industry. However, due to its high cellulose content, the utilization of wheat bran in feed or food processing is limited.

[0004] There are many ways to treat silkworm excrement and wheat bran, the most common of which is composting. Composting is a biodegradation process that converts organic matter in silkworm excrement and wheat bran into humus through the activity of microorganisms, thereby improving soil structure and increasing soil fertility. During the composting process, an appropriate amount of straw, livestock and poultry manure and other organic waste can be added to adjust the carbon-nitrogen ratio, promote microbial activity, and accelerate the maturation of the compost.

[0005] However, the decomposition activities of microorganisms in the traditional composting process will produce foul-smelling gases, such as ammonia and hydrogen sulfide, which can easily have adverse effects on the living environment and human health of surrounding residents. If the temperature in the composting process is not properly controlled and fails to reach a high enough temperature, pathogens and parasite eggs may not be completely killed, which may cause pathogens to spread through compost products, posing a threat to human health and crop growth. In addition, traditional composting requires regular turning of the pile, control of humidity and temperature, etc. These management and maintenance tasks undoubtedly increase labor intensity and management costs.

[0006] Black soldier fly larvae have a strong decomposition ability and can quickly decompose organic matter in silkworm excrement and wheat bran, shortening the processing cycle and improving processing efficiency. The odor generated during the black soldier fly treatment process is much lower than that of traditional composting, because the larvae secrete a special antibacterial substance during the decomposition process, which inhibits the production of odorous gases. During the high-temperature composting process, the body temperature of black soldier fly larvae can reach 60-70℃, which is enough to kill most pathogens and parasite eggs, thereby reducing the risk of disease transmission. The products of black soldier fly treatment can be used as high-quality organic fertilizers to improve soil structure, increase soil water and fertilizer retention capacity, and promote crop growth. In addition, while processing silkworm excrement, black soldier fly larvae will also grow and reproduce, eventually forming high-protein biological feed, which can be used to feed poultry, fish, etc., realizing efficient utilization of resources. Summary of the invention

[0007] Technical problem to be solved: In order to overcome the shortcomings of the existing technology, obtain a method for efficiently and large-scale treatment of silkworm excrement waste, and obtain agricultural organic fertilizer and livestock and poultry feed while eliminating silkworm excrement waste pollution, in view of this, the present invention provides a method for biologically transforming silkworm excrement waste using black soldier flies and the application of its products.

[0008] Technical solution: A method for bioconverting silkworm excrement waste using black soldier flies, the method comprising the following steps:

[0009] S1. Cleaning and domesticating the black soldier fly eggs, and preserving the seeds after natural passage for more than 5 generations in a wheat bran matrix, thereby screening out black soldier fly species with stable reproduction characteristics in a dense breeding environment;

[0010] S2, hatching the black soldier fly species selected in S1 in a wheat bran matrix until obvious larvae are seen;

[0011] S3, pre-treating the collected silkworm excrement waste to control its water content to 70-75% and carbon-nitrogen ratio to 15%-30%;

[0012] S4, transferring the black soldier fly larvae obtained in S2 and the silkworm excrement pre-treated in S3 to a bioconversion pool to perform bioconversion treatment on the silkworm excrement waste;

[0013] S5. Separate the product after the bioconversion treatment in S4 and the black soldier fly larvae, directly use the product as agricultural organic fertilizer, and use the black soldier fly larvae as insect body protein and then use them as breeding feed.

[0014] Preferably, the conditions for acclimation and cultivation in S1 are: the substrate and sterile water are mixed at a ratio of g:mL=1:3-3:7, placed in a round plastic box with a diameter of 10 cm and a height of 20 cm, 1 / 200 of the substrate mass is fed with eggs, and the relative humidity is controlled at 70-75% and the temperature is controlled at 25-30°C.

[0015] Preferably, S2 uses a wheat bran matrix with a moisture content of 80% and a laying height of 8-12 cm to hatch the eggs until obvious insect bodies are seen, and the mass ratio of wheat bran to eggs is 1:200-1:150.

[0016] Preferably, in S3, wheat bran, rice husks, grass meal, wood chips, corn flour, chicken manure and pig manure are used to adjust the carbon-nitrogen ratio of silkworm excrement, and tap water is used to adjust the water content; wherein the mass ratio of wheat bran to silkworm excrement waste is 0:1-1:4, the mass ratio of rice husks to silkworm excrement waste is 1:1-1:3, the mass ratio of grass meal to silkworm excrement waste is 1:1-1:5, the mass ratio of wood chips to silkworm excrement waste is 1:1-1:4, the mass ratio of corn flour to silkworm excrement waste is 1:1-1:5, the mass ratio of chicken manure to silkworm excrement waste is 2:1-1:5, and the mass ratio of pig manure to silkworm excrement waste is 2:1-1:5.

[0017] Preferably, the mass ratio of silkworm excrement waste to wheat bran is 2:1.

[0018] Preferably, in the conversion pool in S4, the laying height of the silkworm feces pretreated in S3 is 12-15 cm, the mass ratio of the pretreated silkworm feces to the larvae is 500:1-1000:1, and the larvae are evenly laid on the surface of the silkworm feces. After laying, the indoor temperature is maintained at 25°C-30°C and the humidity is maintained at 70-75%. The biological conversion treatment is completed after standing for 8-10 days under natural light.

[0019] Furthermore, after standing for 48 hours, the silkworm feces were stirred twice a day, at 9-10 am and 5-6 pm respectively.

[0020] Furthermore, on the 2nd to 6th day of standing, the black soldier fly larvae grew rapidly, and the substrate temperature rose rapidly to 40-50°C through the continuous activity of the larvae. Therefore, the activity of the silkworm excrement substrate microorganisms was increased, so that the black soldier flies could quickly absorb the nutrients in the silkworm excrement waste and continue to grow and develop; on the 2nd day, the silkworm excrement waste became moist due to the activity of the black soldier flies, the moisture increased, and the color became darker; on the 3rd day, the silkworm excrement was moist and sticky, and the amount was significantly reduced.

[0021] Preferably, the specific method for separating the product after bioconversion treatment and the black soldier fly larvae in S5 is: evenly spread the treated silkworm feces with black soldier flies on a sieve with an aperture of 4-7 mm, with a laying thickness of 5-8 mm, and place a layer of geotextile under the sieve, and manually sieve the black soldier flies in the silkworm feces onto the geotextile, wherein the collected silkworm feces are used as dry fertilizer; then the geotextile containing the black soldier flies is transferred to a cleaning pool, and the black soldier flies with silkworm feces on the geotextile are flushed with running water for 3-6 minutes, and the discharged fecal water is collected as water fertilizer; the black soldier flies on the geotextile are collected, air-dried and processed into insect protein, the geotextile is cleaned and the cleaned water is merged into the water fertilizer.

[0022] Preferably, the moisture content of the product after the bioconversion treatment is higher than 70-75%, and it can be directly used as agricultural organic fertilizer after being separated from the black soldier fly larvae. Most preferably, the moisture content of the product after the bioconversion treatment reaches 75%.

[0023] The principle of the method of the present invention is that the present invention can efficiently and comprehensively treat silkworm excrement by using black soldier flies to bio-convert silkworm excrement on a large scale. The black soldier fly larvae can not only increase the temperature of the silkworm excrement matrix by 50°C by constantly turning and stirring the silkworm excrement, but also change the pH value of the matrix, so that the activity of microorganisms in the silkworm excrement matrix is ​​significantly improved, and the decomposition of the silkworm excrement is accelerated. At the same time, the growth and development of the black soldier flies themselves require the rapid absorption of nutrients such as moisture, nitrogen, phosphorus, potassium, sulfur and calcium in the silkworm excrement waste, and effectively convert the nutrients in the silkworm excrement waste into biological organic matter (black soldier fly protein, etc.), preventing the pollution of the environment by sewage, ammonia, hydrogen sulfide and indole and other toxic and harmful gases and bacteria and fungi generated during the natural composting and decomposition of silkworm excrement. According to testing, the water content of the silkworm excrement matrix after being treated by black soldier flies is higher than 70-75%. The above-mentioned method of efficiently and massively treating silkworm excrement using black soldier flies can be used to produce agricultural organic fertilizer.

[0024] In addition, due to the continuous increase in the temperature of the silkworm excrement substrate, most of the pathogenic microorganisms and insect eggs that may exist in the substrate are killed, further improving the safety of the conversion product as a breeding feed. The dry silkworm excrement that has not been processed in time in the substrate can be directly used as feed for black soldier flies after high temperature sterilization.

[0025] Beneficial effects: (1) The method of the present invention regulates the moisture content of silkworm excrement waste by pre-treating the waste, thereby ensuring the normal growth and function of black soldier flies in the matrix; (2) The method of treating silkworm excrement with black soldier flies effectively solves the problems existing in traditional silkworm excrement treatment methods, such as environmental pollution and waste of resources, and converts silkworm excrement into valuable resources. Through the biological transformation of black soldier flies, the organic matter in the silkworm excrement is efficiently utilized, while reducing the dependence on chemical fertilizers. The high protein content of black soldier fly larvae makes it a high-quality feed resource that can be used to feed fish, poultry, etc., while black soldier fly adults can be used as an animal protein source. (3) The economic benefits of this method are very obvious. Due to the short treatment cycle and high conversion efficiency, the production cost can be reduced. At the same time, due to the excellent product quality, a higher market price can be obtained, thereby achieving good economic benefits. In summary, the method of large-scale and efficient transformation of silkworm excrement by black soldier flies has significant advantages. It can not only achieve efficient utilization of waste and reduce environmental pollution, but also bring considerable economic and social benefits. It is a sustainable development model worthy of promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a diagram showing the changes in the state of the silkworm feces matrix before and after the biological transformation of black soldier flies; the left picture shows the state of the silkworm feces matrix before transformation, and the right picture shows the state of the silkworm feces matrix after transformation.

[0027] Figure 2 This is a diagram showing the temperature and pH changes in the silkworm feces matrix during the black soldier fly biotransformation process; the left figure shows temperature and the right figure shows pH. DETAILED DESCRIPTION

[0028] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, modifications and substitutions made to the method, steps or conditions of the present invention all belong to the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0029] Example 1 Highly efficient and large-scale screening and cultivation of black soldier fly species

[0030] The screening and cultivation methods are as follows:

[0031] (1) The eggs of black soldier flies are cleanly raised and domesticated, and the seeds are preserved after being naturally propagated for more than 5 generations in a wheat bran matrix, thereby screening out black soldier fly species with stable reproduction characteristics in an intensive breeding environment.

[0032] (2) The selected black soldier fly species were placed in a wheat bran matrix for incubation. The moisture content of the matrix was 80% and the temperature was 27° C. After 5 days, obvious larvae were seen.

[0033] (3) Collect the larvae of step (2), mix silkworm excrement with wheat bran in the ratio of 1:0, 1:1, 2:1, 3:1, and 4:1 (the specific ratio of this embodiment is shown in Table 1), and divide into 5 groups, each group having 3 repetitions. In this embodiment, 1000 5-day-old larvae are put into each repeated test, and the larvae are prepared into a bioconversion matrix with a moisture content of 73% according to the dry matter mass ratio in Table 1. The initial temperature of the bioconversion is controlled to be 28° C., and all the matrices are fed at one time. The test is terminated when prepupae appear in the treatment group one after another, which is 10 days in this embodiment.

[0034] Before the experiment, the weight of each replicate larvae was weighed as m1, and the weight of each replicate larvae was weighed as m2 on the 10th day. The weight of the larvae after drying was m3, and the weight of the residue after drying was m4. According to formula (1), the larval weight gain rate M1 was calculated, and according to formula (2), the conversion efficiency M2 was calculated.

[0035] Wherein, formula (1) is: M1 = (m2-m1) / m1×100%; formula (2) is: M2 = m3 / (400-m4)×100%.

[0036] Table 1 Ratio of dry matter of silkworm excrement and wheat bran in matrix

[0037] Grouping A1 A2 A3 A4 A5 Silkworm excrement(g) 400 200 266 300 320 Wheat bran(g) 0 200 133 100 80

[0038] After 10 days of black soldier fly biotransformation, the results of this example are as follows: Group A1, insect weight is 83.61g (average value of 3 replicates, larval weight gain rate is 3344.40%; residue weight is 210.99g, and conversion rate is 8.71%. Group A2, insect weight is 118.5g (average value of 3 replicates, larval weight gain rate is 4740.00%; residue weight is 165.04g, and conversion rate is 11.8%. Group A3, insect weight is 151.30g (average value of 3 replicates, larval weight gain rate is 4740.00%; residue weight is 165.04g, and conversion rate is 11.8%. The larvae weight gain rate was the highest, reaching 6052.80%; the residue weight was 205.36g, and the conversion rate was 16.0%. In group A4, the insect weight was 144.5g (the average value of 3 replicates, the larvae weight gain rate was 5780.00%; the residue weight was 197.08g, and the conversion rate was 12.9%. In group A5, the insect weight was 121.08g (the average value of 3 replicates, the larvae weight gain rate was 4843.20%; the residue weight was 203.18g, and the conversion rate was 11.2%.

[0039] From the above results, it can be seen that when the mass ratio of silkworm feces to wheat bran is 2:1, the larval weight gain rate and conversion rate are the highest, indicating that this ratio is most conducive to the growth, development and bioconversion of black soldier flies.

[0040] Example 2 Large-scale bioconversion of silkworm excrement using black soldier flies

[0041] According to the test results of Example 1, the mass ratio of silkworm excrement to wheat bran in this example is 2:1, the moisture content of the substrate is adjusted to 73% by pretreatment, the initial temperature is controlled to 28°C, and 5-day-old black soldier fly larvae are added.

[0042] The silkworm excrement in the conversion pool is laid at a height of 12 cm. Each batch of each pool can process 1 ton of silkworm excrement, and the mass ratio of pre-treated silkworm excrement to larvae is 600:1. After standing for 48 hours, the silkworm excrement is stirred twice a day, at 9-10 am and 5-6 pm respectively. Black soldier fly larvae are added for 10 days to complete a round of biological conversion treatment, after which the larvae and the substrate are separated.

[0043] On the second day, the silkworm excrement waste became moist due to the activity of black soldier flies, with increased moisture and darker color; on the third day, the silkworm excrement was moist and sticky, and the amount was significantly reduced. Figure 1 shown.

[0044] The black soldier fly biotransformation process of silkworm excrement can also significantly affect the temperature and pH of the substrate. The changes in temperature and pH make the substrate environment more suitable for the growth and reproduction of various microorganisms, thereby accelerating the maturation of the substrate. Figure 2 shown. Figure 2The control group was a natural treatment group without the addition of black soldier flies.

[0045] After testing, the moisture content of the substrate after bioconversion reached 75%, the nitrogen, phosphorus and potassium content was higher than 5%, the organic matter content was higher than 53%, the heavy metal content was within the qualified range, and the ascaris egg mortality rate was higher than 96%. The test results show that the treated silkworm feces substrate meets the requirements of NY 884-2012 and can be used as agricultural organic fertilizer.

[0046] Example 3 Effect of Black Soldier Fly Protein Feed on Growth Performance of Broilers

[0047] The black soldier flies treated for 10 days in Example 2 were separated from their feces, and the separated black soldier fly larvae were rinsed with clean water, filtered and stored at -20°C for later use.

[0048] Preparation of black soldier fly powder: thaw the black soldier flies stored at -20°C, dry them at 50°C for 24 hours, crush the dried black soldier flies with a homogenizer, pass them through a 40-mesh sieve, seal them, and store them at -20°C for later use.

[0049] Determination of nutritional components: The results of the determination of nutritional components of black soldier flies are shown in Table 2, which were carried out according to the method of Liu Xingyou and Diao Youxiang (1995). Moisture determination: loss on drying method; protein determination: KJ1030 Kjeldahl automatic nitrogen analyzer; fat determination: Soxhlet extraction method; ash determination: Muffle furnace ashing method.

[0050] Table 2 Basic nutritional composition of black soldier fly powder

[0051]

[0052] Effect of black soldier fly protein feed on the growth performance of broilers: 50 broilers of the same age and similar growth performance were randomly divided into two groups, one group of 25, half male and half female. The control group was fed with commercial conventional feed, and the test group was fed with 10% black soldier fly protein as improved feed. The feed was fed continuously for 80 days, and the feeding was stopped for 24 hours after the end of the experiment. The final body weight of broilers in each group was weighed, and the birth weight, final body weight, average daily weight gain, average daily feed consumption, feed-to-weight ratio and survival rate were calculated. The results are shown in Table 3. It can be seen from the table that adding black soldier fly protein powder can significantly improve the production performance of broilers, reduce production costs, accelerate the growth rate of broilers, and reduce the feed-to-meat ratio.

[0053] Table 3 Effects of new black soldier fly protein feed on broiler growth performance

[0054]

[0055] Note: Data in the same row with different lowercase letters indicate significant differences (P<0.05).

Claims

1. A method for bioconverting silkworm excrement waste using black soldier flies, characterized in that: The method comprises the following steps: S1. Cleaning and domesticating the black soldier fly eggs, and preserving the seeds after natural passage for more than 5 generations in a wheat bran matrix, thereby screening out black soldier fly species with stable reproduction characteristics in a dense breeding environment; S2, hatching the black soldier fly species selected in S1 in a wheat bran matrix until obvious larvae are seen; S3, pre-treating the collected silkworm excrement waste to control its water content to 70-75% and carbon-nitrogen ratio to 15-30%; S4, transferring the black soldier fly larvae obtained in S2 and the silkworm excrement pre-treated in S3 to a bioconversion pool to perform bioconversion treatment on the silkworm excrement waste; S5. Separate the product after the bioconversion treatment in S4 and the black soldier fly larvae, directly use the product as agricultural organic fertilizer, and use the black soldier fly larvae as insect body protein and then use them as breeding feed.

2. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 1, characterized in that: The conditions for domestication and cultivation in S1 are as follows: the substrate and sterile water are mixed at a ratio of g:mL=1:3-3:7, placed in a round plastic box with a diameter of 10 cm and a height of 20 cm, and eggs are fed at 1 / 200 of the substrate mass, and the relative humidity and temperature are controlled at 70-75% and 25-30°C.

3. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 1, characterized in that: S2 uses a wheat bran matrix with a moisture content of 80% and a laying height of 8-12 cm to hatch the eggs until obvious insect bodies are seen, and the mass ratio of wheat bran to eggs is 1:200-1:

150.

4. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 1, characterized in that: In S3, wheat bran, rice husks, grass meal, wood chips, corn flour, chicken manure and pig manure are used to adjust the carbon-nitrogen ratio of silkworm excrement, and tap water is used to adjust the water content; among them, the mass ratio of wheat bran to silkworm excrement waste is 0:1-1:4, the mass ratio of rice husks to silkworm excrement waste is 1:1-1:3, the mass ratio of grass meal to silkworm excrement waste is 1:1-1:5, the mass ratio of wood chips to silkworm excrement waste is 1:1-1:4, the mass ratio of corn flour to silkworm excrement waste is 1:1-1:5, the mass ratio of chicken manure to silkworm excrement waste is 2:1-1:5, and the mass ratio of pig manure to silkworm excrement waste is 2:1-1:

5.

5. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 4, characterized in that: The mass ratio of silkworm excrement waste to wheat bran is 2:

1.

6. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 1, characterized in that: In the conversion pool S4, the silkworm feces pretreated by S3 are laid at a height of 12-15 cm, the mass ratio of the pretreated silkworm feces to the larvae is 500:1-1000:1, and the larvae are evenly laid on the surface of the silkworm feces. After laying, the indoor temperature is maintained at 25°C-30°C and the humidity is maintained at 70-75%. Under natural light, the biological conversion treatment is completed after standing for 8-10 days.

7. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 6, characterized in that: After standing for 48 hours, stir the silkworm feces twice a day, at 9-10 am and 5-6 pm respectively.

8. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 6, characterized in that: On the 2nd to 6th day of static placement, the black soldier fly larvae grow rapidly, and through the continuous activity of the larvae, the substrate temperature quickly rises to 40℃-50℃.

9. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 1, characterized in that: The specific method for separating the products after bioconversion treatment and the black soldier fly larvae in S5 is as follows: the treated silkworm feces containing black soldier flies are evenly spread on a sieve with an aperture of 4-7 mm and a thickness of 5-8 mm, a geotextile is placed under the sieve, and the black soldier flies in the silkworm feces are manually sieved onto the geotextile, wherein the collected silkworm feces are used as dry fertilizer; then the geotextile containing the black soldier flies is transferred to a cleaning pool, and the black soldier flies containing silkworm feces on the geotextile are flushed with running water spray for 3-6 minutes, and the discharged fecal water is collected as water fertilizer; the black soldier flies on the geotextile are collected, air-dried and processed into insect protein, the geotextile is cleaned and the cleaning water is added to the water fertilizer.

10. The method for bioconverting silkworm excrement waste using black soldier flies according to claim 9, characterized in that: The moisture content of the product after biological transformation treatment is higher than 70-75%, and it can be directly used as agricultural organic fertilizer after being separated from the black soldier fly larvae.

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