A method for improving the availability of cyanobacteria and the conversion rate of black soldier fly by ultraviolet treatment

Abstract

The present invention belongs to the technical field of resource treatment of organic solid waste, and particularly relates to a method for improving the availability of cyanobacteria and the conversion rate of black soldier fly by ultraviolet treatment. The present invention uses a pasteurization process at 65°C for 30 minutes to treat cyanobacteria, which can effectively kill bacterial spores, Escherichia coli and inactivate spoilage enzymes, and helps to improve the availability of cyanobacteria. When using an ultraviolet device to treat cyanobacteria, under the irradiation of high-intensity ultraviolet rays for 30 minutes, the algal toxins are effectively decomposed, so that the anti-nutritional factors in cyanobacteria are effectively reduced. Compared with directly using cyanobacteria, the compounding of wheat bran and cyanobacteria improves the carbon-nitrogen ratio and pore structure of the feed, thereby enhancing the survival rate of black soldier fly, the weight of the produced insects and the reduction rate of cyanobacteria. The present invention has the characteristics of low carbon, no energy consumption and environmental friendliness.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource treatment of organic solid waste, and particularly relates to a method for improving the availability of cyanobacteria and the conversion rate of black soldier fly by ultraviolet treatment. Background Art

[0002] Cyanobacterial bloom refers to the phenomenon that a large number of cyanobacteria-dominated algae in eutrophic water bodies multiply in a short time and gather on the water surface to form a cyanobacteria layer with high density and large area, causing an obvious visible water discoloration. The outbreak of cyanobacterial bloom will lead to an increase in water turbidity and a decrease in dissolved oxygen. The death of algae will decompose and release a large amount of nutrients and toxic metabolites such as algal toxins, which will cause serious impacts on the water ecological environment and production and life. The mechanical salvage method is a direct, safe and effective emergency and treatment measure to reduce cyanobacterial ecological disasters and protect the water ecological environment at present. However, the salvaged cyanobacteria are easy to rot and contain various pollutants. If they cannot be disposed of in time and effectively and are stacked randomly, it will cause secondary pollution to the environment. At present, the main means of treating algal sludge is the incineration method (treatment capacity: 1000 tons / day), which not only consumes a large amount of fuel but also emits waste gas. In order to achieve the goal of energy conservation and emission reduction, it is urgent to develop a low-cost and high-efficiency cyanobacteria resource technology.

[0003] Compared with traditional foods, cyanobacteria contain higher-quality proteins, essential amino acids, unsaturated fatty acids, carbohydrates and other nutrients and various vitamins. The dry matter contains about 30-55% protein. Using algae as a potential raw material product and a supplement for food has broad application prospects. However, because algae contain a large number of anti-nutritional factors such as algal toxins and trypsin, direct addition as feed may have an inhibitory effect on the growth of animals. Therefore, cyanobacteria need to be further processed. At present, how to dispose of cyanobacteria into feed suitable for biological conversion still needs further exploration.

[0004] Compared with other breeding insects, the black soldier fly has a wider feeding range, which makes the use of black soldier fly to treat organic waste receive more and more attention. It is found that the black soldier fly can feed on organic wastes such as animal feces, food waste, bean curd residue, fermented straw, biogas residue, etc. During the biological conversion of organic waste by the black soldier fly, the waste can be converted into the biomass of the black soldier fly itself and produce high-value-added lipids and proteins. According to research, the nutritional components of organic waste have a huge impact on the growth and development of larvae, and the protein content is the most important. The development of black soldier fly larvae requires sufficient protein, and cyanobacteria have a high protein content, which makes it possible to use cyanobacteria as a feed protein supplement to feed black soldier fly.

[0005] In view of the high content of cyanobacteria protein and its easy acquisition, the present invention proposes a new process for the resource utilization of cyanobacteria based on the biological transformation of black soldier flies, and improves the availability of cyanobacteria and the transformation efficiency of black soldier flies by ultraviolet treatment of cyanobacteria. Compared with the incineration of accumulated cyanobacteria, the biological transformation method can not only produce insect protein but also reduce the environmental damage caused by the incineration of cyanobacteria, which is more energy-saving and environmentally friendly, and has the substantial technical characteristics of energy saving and emission reduction. Summary of the invention

[0006] The cyanobacteria salvaged from the shore contain anti-nutritional factors such as algae toxins, and have a high water content, which makes it unfavorable for the growth of organisms to directly use it as feed. If it is to be used as a resource, it needs to be further processed. In order to solve the problem of cyanobacteria as feed, the present invention provides a method for improving the availability of cyanobacteria and the conversion rate of black soldier flies by ultraviolet treatment. On the one hand, it can solve the problem of cyanobacteria accumulation, and on the other hand, the cultivated larvae have high economic value and can be used as a protein source for animal feed or a lipid source for producing biodiesel.

[0007] The technical solution of the present invention is: a method for improving the availability of cyanobacteria and the conversion rate of black soldier flies by ultraviolet treatment, and the specific steps are as follows:

[0008] (1) placing the salvaged fresh blue algae in an ultraviolet heating device to be sterilized by high temperature and irradiated by ultraviolet light;

[0009] (2) drying the irradiated cyanobacteria and crushing them in a wall-breaking machine, and filtering the cyanobacteria powder through a sieve for later use;

[0010] (3) Compounding blue algae with wheat bran to adjust the carbon-nitrogen ratio of the feed;

[0011] (4) Control the moisture content of the prepared feed to an appropriate level;

[0012] (5) placing the black soldier fly eggs in a temperature and humidity controlled incubator for hatching;

[0013] (6) inoculating the hatched black soldier flies into the feed in proportion for bioconversion;

[0014] (7) When 50% of the black soldier flies in the group enter the prepupae stage, the insect bodies are separated from the insect sand.

[0015] In one embodiment of the present invention, the temperature of the ultraviolet treatment device is set to 60-65° C., and the duration is set to 30-60 minutes.

[0016] In one embodiment of the present invention, a 253.7 nm ultraviolet lamp is used in an ultraviolet treatment device to irradiate the algae mud to be treated, which can effectively reduce the algae toxin content.

[0017] In an embodiment of the present invention, the ultraviolet intensity is not less than 70 μW / cm 2 .

[0018] In an embodiment of the present invention, the ultraviolet high-temperature device includes: a housing bracket, an ultraviolet high-temperature device housing, an ultraviolet lamp bracket, an ultraviolet lamp assembly, an ultraviolet intensity detector, a temperature controller, a heating plate, a loading tray, and a tray fixing bracket; the ultraviolet lamp assembly is installed on the side wall of the device by relying on the ultraviolet lamp bracket, and the ultraviolet lamp assembly is composed of 5 to 6 ultraviolet lamps with an ultraviolet intensity not less than 70 μW / cm 2 . The lamp tubes are installed vertically to the ground; the device heating assembly is composed of a temperature controller and a heating plate.

[0019] In an embodiment of the present invention, the loading tray is a mesh material that does not affect the transmission of ultraviolet rays.

[0020] In an embodiment of the present invention, the number of the loading trays is 5 to 10, preferably 8.

[0021] In an embodiment of the present invention, the ultraviolet high-temperature device is used to process cyanobacteria to improve the availability of cyanobacteria and the conversion rate of black soldier fly. The ultraviolet high-temperature device includes: a housing bracket 1, an ultraviolet high-temperature device housing 2, an ultraviolet lamp bracket 3, an ultraviolet lamp assembly 4, an ultraviolet intensity detector 5, a temperature controller 6, a heating plate 7, a loading tray 8, and a tray fixing bracket 9. The front view of the two rows of ultraviolet lamp assemblies on the side wall of the device is as shown in Figure 5 . Each ultraviolet lamp assembly is composed of 6 ultraviolet lamps with an ultraviolet intensity not less than 70 μW / cm 2 . The lamp tubes are installed vertically to the ground to better irradiate the cyanobacteria on each layer of the tray. The front view of the device heating assembly is shown in Figure 6 . The heating assembly is composed of a temperature controller and a heating plate, and the temperature is set to 65°C. At the beginning of the experiment, open the front door of the device, evenly spread the cyanobacteria on the tray rack in the middle of the device, and the thickness of each layer of the tray is about 2 - 3 cm. Adjust the temperature controller and set the temperature to 65°C. The heating and ultraviolet irradiation times are both set to 30 minutes. Close the hatch and wait for heating and ultraviolet treatment. The ultraviolet intensity detector can detect the ultraviolet intensity in real time. After the treatment is completed, open the hatch, let the cyanobacteria cool slightly, and then carry out subsequent treatment. Among them, the 30-minute high-temperature treatment can control part of the moisture and inactivate most of the pathogenic microorganisms, and the continuous ultraviolet irradiation can achieve the effect of degrading algal toxins.

[0022] In an embodiment of the present invention, the treated cyanobacteria are dried and ground for subsequent use.

[0023] In one embodiment of the present invention, the compounding of wheat bran and cyanobacteria adjusts the feed to an appropriate carbon-nitrogen ratio on the one hand and enhances the pore structure of the feed on the other hand.

[0024] In one embodiment of the present invention, the carbon-nitrogen ratio of the adjusted feed should be between 6 and 7.

[0025] In one embodiment of the present invention, wheat bran and cyanobacteria are compounded at a dry matter ratio of 40-70:30-60.

[0026] In one embodiment of the present invention, the prepared feed has a moisture content of 60%-80%, which is in line with the suitable growth environment of black soldier fly.

[0027] In one embodiment of the present invention, the feed for hatching black soldier fly eggs is wheat bran with a moisture content of 50%, and the hatching temperature is controlled at 25°C-32°C, and the humidity is controlled at 60%-70%.

[0028] In one embodiment of the present invention, the black soldier fly selected in step (6) is an 8-day-old black soldier fly larva.

[0029] In one embodiment of the present invention, the inoculation ratio of black soldier fly larvae in step (6) is selected as 2 larvae per 1 g of feed dry matter. The environmental temperature for the growth and development of black soldier fly is controlled at 25°C-32°C.

[0030] The present invention can improve the availability of cyanobacteria and achieve a higher bioconversion rate of black soldier fly by using the above method to treat cyanobacteria.

[0031] The second object of the present invention is to use the above-harvested black soldier fly for the production of animal feed and biodiesel.

[0032] The third object of the present invention is to solve the problem of accumulated cyanobacteria through the bioconversion effect of black soldier fly and simultaneously produce prepupae with high added value.

[0033] The fourth object of the present invention is that using an ultraviolet device to treat algal sludge has the technical characteristics of being simple and effective.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Using the pasteurization process at 65°C for 30 minutes to treat cyanobacteria can effectively kill bacterial spores, Escherichia coli and inactivate spoilage enzymes, which helps to improve the availability of cyanobacteria.

[0036] (2) Using an ultraviolet device to treat cyanobacteria, under the irradiation of high-intensity ultraviolet light for 30 minutes, the algal toxins are effectively decomposed, and the antinutritional factors in cyanobacteria are effectively reduced.

[0037] (3) Compared with directly using cyanobacteria, the compounding of wheat bran and cyanobacteria improves the carbon-nitrogen ratio and pore structure of the feed, enhancing the survival rate of black soldier flies, the weight of the produced larvae, and the reduction rate of cyanobacteria.

[0038] (4) The feed prepared from cyanobacteria treated by the ultraviolet device and wheat bran has less interference with the growth and development of the larvae, and the larvae have higher utilization efficiency of protein, fat, and starch, with better growth conditions.

[0039] (5) The operation of the present invention is simple, with high efficiency in treating cyanobacteria and a short treatment cycle.

[0040] (6) The present invention features low carbon, no energy consumption, and environmental friendliness.

[0041] (7) Using black soldier flies for biotransformation of cyanobacteria can harvest black soldier fly prepupae with relatively high protein and fat contents while degrading cyanobacteria, which has certain economic viability.

[0042] Black soldier flies can inhibit the growth of microbial pathogens in the feed substrate, and the remaining substrate after being treated by black soldier flies can also be used as organic fertilizer or as raw material for its anaerobic digestion. Description of the Drawings

[0043] Figure 1 Algae toxin concentrations in the feeds of each treatment group;

[0044] Figure 2 Antioxidant enzyme activities of the larvae in each treatment group. On the left are the activities of SOD and CAT, and on the right are the activities of GSH and MAD;

[0045] Figure 3 Digestive enzyme activities of the larvae in each treatment group;

[0046] Figure 4 Diagram of the ultraviolet treatment device, including housing bracket 1, ultraviolet high-temperature device housing 2, ultraviolet lamp bracket 3, ultraviolet lamp assembly 4, ultraviolet intensity detector 5, temperature controller 6, heating plate 7, carrier tray 8, and tray fixing bracket 9;

[0047] Figure 5 Front view of the ultraviolet lamp assembly;

[0048] Figure 6 Front view of the heating assembly. Detailed Embodiments

[0049] The present invention is further described below in combination with specific embodiments and experimental data. The specific schemes in the embodiments of the present invention are all conventional schemes unless otherwise specified. The reagents or formulations used can be purchased from regular stores if not specifically stated.

[0050] The experiment was conducted in a container with dimensions of 8.4 cm × 14 cm × 4.5 cm.

[0051] Water content measurement method: Weigh the crucible. After putting the item to be measured into the crucible, weigh the total weight of the crucible and the item to be measured. Put the crucible into the oven and bake it until it reaches a constant weight, then take out the crucible and weigh the total weight.

[0052] Microcystin measurement method: Preparation of the sample to be measured: Weigh 1 g of dry sample and grind it into powder. Add 10 ml of 75% methanol solution and stir magnetically at room temperature for 2 h, then perform ultrasonic treatment. The extract is centrifuged at 8000×g for 10 min at 4 °C. Absorb the supernatant and adjust its pH to 3.0, then centrifuge to remove impurity proteins. The supernatant is filtered through a 0.45 μm microporous membrane and its pH value is adjusted to 7.0. After removing methanol by rotary evaporation, collect the remaining liquid and dissolve it in 5 mL of ultrapure water for use. The concentration of MC-LR is measured by high performance liquid chromatography (Ultimate 3000, Dionex Corporation, USA). Wavelength of the ultraviolet visible light detector: 238 nm, column temperature: 40 °C, mobile phase: methanol and phosphate buffer with pH = 3 (57:43, v:v), column flow rate: 1 mL·min-1.

[0053] The calculation formula is:

[0054] Water content = 1 - (total weight of the initial crucible and material - weight of the crucible) / (total weight of the crucible and material after constant weight - weight of the crucible) × 100% Survival rate = number of surviving larvae / total number of added larvae × 100%

[0055] Bioconversion rate = total mass of harvested black soldier fly dry matter / dry matter weight of the initial feed × 100%

[0056] Feed conversion rate = (dry matter weight of the initial feed - dry matter weight of the remaining insect frass) / (dry weight of harvested black soldier fly - dry weight of added black soldier fly) × 100%

[0057] Dry matter reduction rate = 1 - dry matter weight of insect frass / dry matter weight of the initial feed × 100%

[0058] Example 1: Optimization of adding wheat bran to cyanobacteria

[0059] (1) Adjust the water content of the salvaged cyanobacteria sludge to 70% as feed for use, named T0.

[0060] (2) Add wheat bran to cyanobacteria according to a dry matter ratio of 1:1 and adjust the water content to 70% to make a mixed feed for use, named T1.

[0061] (3) Add 100 g (dry matter) of feed to the feed box, and then inoculate 200 8-day-old black soldier flies.

[0062] (4) Observe the growth status of each group of black soldier flies. After 50% of the black soldier flies in a group enter the prepupal stage, separate the insect bodies from the insect frass, and record the remaining number and weight of black soldier flies and the remaining feed weight, which are used to calculate the dry matter reduction rate, biological conversion rate, feed conversion rate, larval survival rate, and total weight of harvested prepupae.

[0063] Table 1 Comparison of the growth and development status of black soldier flies in pure cyanobacteria feed and cyanobacteria-wheat bran compound feed

[0064]

[0065] Note: In the same column of data, the same letters indicate no significant difference (P > 0.05), and the values are expressed as mean ± standard deviation.

[0066] Previous studies have found that excessive nitrogen-rich substances can lead to an increase in larval mortality and a decrease in biological conversion efficiency. Adding an appropriate amount of nitrogen-rich aquaculture waste is beneficial to the development of larvae, while excessive use of nitrogen-rich substances may have negative effects such as larval death and biomass loss.

[0067] From the data in Table 1, it can be seen that the growth and development status of black soldier flies on pure cyanobacteria mud is poor. The total weight gain after inoculating larvae is 1.88 g, and the number of surviving black soldier flies does not reach half of the total number. The biological conversion rate and dry matter reduction rate are at a low level. Generally speaking, using only pure cyanobacteria as feed to raise black soldier flies is not ideal. After adding an appropriate amount of wheat bran, the total weight of harvested black soldier fly larvae, survival rate, biological conversion rate, etc. have been significantly improved. Among them, the output insect weight has increased by 14.08 times, and the biological conversion rate has increased by 6.44 times. Adding wheat bran not only increases the carbon-nitrogen ratio in the feed, making it more suitable for larvae to ingest the feed, but also the fluffy structure of wheat bran improves the air permeability of the feed, which is more conducive to the survival of larvae.

[0068] Example 2

[0069] A method for improving the availability of cyanobacteria and the conversion rate of black soldier flies by ultraviolet treatment, including the following steps:

[0070] (1) Ultraviolet treatment of cyanobacteria salvaged ashore:

[0071] Ultraviolet treatment of cyanobacteria by the device: Open the front door of the device, evenly spread the cyanobacteria on the tray rack in the middle of the device. The thickness of each layer of tray is about 2 - 3 cm. Adjust the temperature controller, set the temperature to 65 °C, set both the heating and ultraviolet irradiation time to 30 mins, close the hatch, wait for heating and ultraviolet treatment, and the ultraviolet intensity detector can detect the ultraviolet intensity in real time. After the treatment is completed, open the hatch, dry the treated cyanobacteria and then put it into a blender to break it up. The cyanobacteria powder is sieved through a 20-mesh sieve and reserved for use.

[0072] (2) Compound cyanobacteria with wheat bran:

[0073] Select an appropriate amount of wheat bran, and mix the cyanobacteria and wheat bran in a ratio of 1:1 of the dry matter of cyanobacteria to wheat bran by stirring to prepare the feed. Adjust the moisture content of the substrate to 70% by adding distilled water, and collect part of the feed for detecting its substance content and physical state.

[0074] (3) Select an appropriate amount of wheat bran, adjust its moisture content to 50%, place about 2 g of eggs on the surface of the prepared wheat bran, and then place the whole in a biochemical incubator for hatching. The temperature of the biochemical incubator is adjusted to 30 °C and the humidity is adjusted to 70%.

[0075] (4) Observe the hatching situation of the eggs, and start calculating the age in days when most of them have hatched.

[0076] (5) Inoculate the black soldier flies at 8 days old into each group, inoculate 200 larvae per 100 g of feed (dry matter), and place them in a biochemical incubator at a temperature of 30 °C and a humidity of 70% for cultivation.

[0077] (6) Observe the growth status of the black soldier flies in each group. After 50% of the black soldier flies in the group enter the prepupal stage, separate the insect bodies from the insect frass.

[0078] (7) The harvested larvae and material residues are used to calculate the dry matter reduction rate, biological conversion rate, feed conversion rate, larval survival rate, and total weight of harvested prepupae.

[0079] Comparative Example 1

[0080] Control experiment on feeding black soldier flies with feed prepared from cyanobacteria and wheat bran without treatment by ultraviolet device:

[0081] Take an appropriate amount of cyanobacteria sludge that has not been treated directly by ultraviolet device and dried, and mix the cyanobacteria and wheat bran in a ratio of 1:1 of the dry matter of cyanobacteria to wheat bran by stirring to prepare the feed. Adjust the moisture content of the substrate to 70% by adding distilled water, and collect part of the feed for detecting its substance content. The hatching, cultivation conditions and separation operations of black soldier flies are the same as those in Example 1.

[0082] The results are as follows:

[0083] By measuring the microcystins in the substrates of different groups, the obtained results are as Figure 1 shown.

[0084] From Figure 1 it can be seen that: during the treatment of cyanobacteria sludge by ultraviolet device, the microcystins are degraded by ultraviolet irradiation, resulting in the significantly lower content of microcystins (445.24 μg / g) in the ultraviolet group than that in the high-temperature group (586.67 μg / g). Microcystins have certain toxicological effects on animals, and the difference in microcystin content may be one of the reasons for the better growth status of black soldier fly larvae in the ultraviolet group.

[0085] There are differences in the interference of substrates in different groups on Hermetia illucens, resulting in different feed utilization rates of Hermetia illucens. The activity of antioxidant enzymes can characterize the degree of interference of cyanobacteria on the growth and development of Hermetia illucens after treatment with the ultraviolet device, and the activity of digestive enzymes in the insect body can reflect the feed utilization rate of Hermetia illucens. The detection results are as Figure 2 and Figure 3 .

[0086] Figure 2 Figure shows the antioxidant enzyme activities in the larvae of different substrates. SOD and CAT are antioxidant enzymes widely present in organisms, and their activities can reflect the degree of interference of the external environment on the insect body. GSH is a key antioxidant and free radical scavenger in cells, and more GSH needs to be consumed when facing stronger interference. MDA is an important parameter reflecting the antioxidant potential of the insect body. It can be seen from the figure that the activities of SOD and CAT enzymes in the insect body in the cyanobacteria substrate of the ultraviolet device group are lower than those in the control group. The activities of SOD and CAT in the control treatment group are 58.49 U / mg prot and 9.94 U / mg prot, while those in the ultraviolet device group are only 45.29 U / mg prot and 3.61 U / mg prot. Similarly, the activity of MDA enzyme under the treatment of the ultraviolet device is significantly lower than that in the control group, while the activity of GSH changes contrary to the activities of the other three enzymes. This shows that the treatment of cyanobacteria with the ultraviolet device has less interference on the Hermetia illucens body compared with the control group.

[0087] Figure 3 Figure shows the activities of protease, lipase and amylase in the insect body of different treatment groups. The activity of digestive enzymes in the insect body fed with cyanobacteria after treatment with the ultraviolet device is significantly higher than that in the control group. The activities of lipase, amylase and protease in the insect body in the ultraviolet device group reach 13.41 μmol / min / g, 2.19 mg / min / g and 69.12 nmol / min / g respectively, while the highest activities of each digestive enzyme in the insect body of the control group only account for 64.36%, 55.71% and 55.43% of those in the ultraviolet group. The nutrients utilized by Hermetia illucens are mainly protein, fat and carbohydrates. It can be seen that Hermetia illucens has a stronger absorption ability for the nutrients in the cyanobacteria after ultraviolet treatment.

[0088] The growth and development status of larvae in different groups are shown in Table 2:

[0089] Table 2 Growth and development of larvae in each group

[0090]

[0091] Note: The same letters in the same column of data indicate no significant difference (P > 0.05), and the values are expressed as mean ± standard deviation.

[0092] As can be seen from Table 4, when the blue algae treated by the ultraviolet device were used as the substrate to feed the black soldier fly, the weight of the prepupae obtained was significantly higher than that of the control group. In terms of survival rate, the ultraviolet device group was also higher than the control group. The feed conversion ratio and biological conversion rate can reflect the utilization of feed by the larvae. The biological conversion rate of the black soldier fly in the ultraviolet device group (6.65%) was 43.01% higher than that of the control group (4.65%). Similarly, the feed conversion ratio of the ultraviolet device group (7.87) was also significantly lower than that of the control group (10.55).

[0093] Through continuous observation of the process of the black soldier fly bioconverting blue algae, it was found that when only blue algae were used as the substrate to raise the black soldier fly, due to reasons such as low substrate air permeability and unsuitable carbon-nitrogen ratio structure, the conversion effect of the black soldier fly was not ideal. Adding an appropriate proportion of wheat bran to the blue algae could improve the porosity on the one hand and the feed nutritional structure on the other hand, thus significantly improving the bioconversion effect of the black soldier fly. Compared with the control group, the black soldier fly in the ultraviolet device group continuously ingested the substrate and was quickly converted into its own biomass. During the conversion process of about 14 - 16 days, the weight of the black soldier fly increased by 40 - 55 times. The ultraviolet treatment has the following advantages: (1) In terms of material composition, the content of algal toxins in the substrate after being treated by the ultraviolet device is lower, and the availability of the substrate for the black soldier fly is higher; (2) From the perspective of interference to the insect body, the feed after being treated by the ultraviolet device has lower interference to the insect body, and the reduction of anti-nutritional factors in the substrate makes the digestive enzyme activity of the insect body higher and more conducive to the feeding on blue algae. (3) After the ultraviolet device treats blue algae, it can significantly improve the conversion efficiency of the black soldier fly to blue algae, resulting in an increase in the output of larvae and an increase in the reduction of blue algae. It can achieve the treatment principles of "harmlessness, reduction, low-carbonization, and resource utilization" of blue algae mud.

[0094] The present invention provides a new idea for the harmless utilization of blue algae and has practical guiding significance for the application of the black soldier fly bioconverting blue algae. After the treated blue algae are bioconverted by the black soldier fly, on the one hand, high-value-added black soldier fly prepupae can be produced, and on the other hand, the remaining insect feces can also be used as aerobic composting materials, solving the problem of blue algae accumulation while realizing the resource utilization and waste-free utilization of blue algae, and having the substantial technical characteristics of energy conservation and emission reduction.

Claims

1. A method for improving the availability of cyanobacteria and the conversion rate of black soldier fly by ultraviolet treatment, the specific steps are as follows: (1) Place the salvaged fresh blue-green algae in an ultraviolet heating device to be irradiated by an ultraviolet lamp while undergoing high-temperature sterilization; the temperature is set at 60 - 65 degrees, and the duration is set at 30 - 60 mins; the ultraviolet intensity is not less than 70 μW / cm 2 ; (2) Dry the irradiated cyanobacteria and put them into a blender to break them. After the cyanobacteria powder passes through a sieve, it is reserved for use; (3) Compound the cyanobacteria with wheat bran to adjust the carbon-nitrogen ratio of the feed; the wheat bran and cyanobacteria are compounded at a dry matter ratio of 40-70:30-60; the carbon-nitrogen ratio is between 6 and 7; (4) Control the moisture content of the prepared feed at 60-80%; (5) Put the eggs of black soldier fly into an incubator with controlled temperature and humidity for hatching; the feed for hatching the eggs of black soldier fly is wheat bran with a moisture content of 50%, the hatching temperature is controlled at 25°C - 32°C, and the humidity is controlled at 60% - 70%; (6) Inoculate the hatched black soldier fly into the feed according to a certain proportion for bioconversion; (7) After 50% of the black soldier fly in the group enters the prepupal stage, separate the insect body from the insect frass; The ultraviolet high-temperature device includes: a housing bracket, an ultraviolet high-temperature device housing, an ultraviolet lamp bracket, an ultraviolet lamp assembly, an ultraviolet intensity detector, a temperature controller, a heating plate, a carrier tray, and a tray fixing bracket; The ultraviolet lamp assembly is mounted on the side wall of the device by relying on an ultraviolet lamp bracket. The ultraviolet lamp assembly is composed of 5 to 6 ultraviolet lamps with an ultraviolet intensity of not less than 70 μW / cm 2 . The lamp tubes are installed vertically to the ground. The device heating assembly is composed of a temperature controller and a heating plate. The load tray is made of a mesh material that does not affect the transmission of ultraviolet rays. The number of the load trays is 5 to 10.

2. According to the method described in claim 1, characterized in that, In the ultraviolet treatment device, a 253.7 nm ultraviolet lamp is used to irradiate the algal sludge to be treated.

3. According to the method described in claim 1, characterized in that, The black soldier fly selected in step (6) is an 8-day-old black soldier fly larva.

4. According to the method described in any one of claims 1 to 3, the harvested black soldier fly is used for the production of animal feed and biodiesel.

Images