Method for reducing content of hermetia illucens sand salt in process of converting hermetia illucens into kitchen waste

Abstract

According to the method for reducing the content of the insect sand salt in the technology for converting the hermetia illucens into the kitchen waste, the kitchen waste is fed and supplied to hermetia illucens larvae in different growth stages in batches according to different feeding proportions in a batch feeding mode, and the larvae and the insect sand are separated before the kitchen waste is fed every time, so that the salt content of the larvae is reduced; the problem that the content of salt in insect sand is too high due to incomplete conversion, concentration effect and the like can be effectively avoided. And meanwhile, the kitchen waste treatment efficiency of the hermetia illucens larvae and the larva yield can be improved. Through the feeding strategy of feeding in batches, the content of salt transferred into the hermetia illucens sand in the hermetia illucens transformation process can be reduced by 43%, and meanwhile the yield of the hermetia illucens larvae at the end of transformation is increased by 69%.

Description

Technical Field

[0001] The present application relates to the technical field of organic solid waste treatment, and in particular to a method for reducing the content of insect sand salt in a process of converting food waste by black soldier flies. Background Art

[0002] Food waste refers to a mixture of food residues, food processing waste and other wastes generated in the process of human production and life. It has the dual nature of resources and waste. The main treatment method for food waste at present is to follow the treatment method of domestic waste, that is, incineration. However, the calorific value of food waste is low and the economy of incineration is poor. Therefore, it is necessary to seek a more suitable treatment method for food waste. Due to the high organic matter content in food waste, it is more suitable to use biological transformation to recover the organic components therein. Therefore, anaerobic fermentation and aerobic composting have become the main biological treatment methods for food waste treatment. However, anaerobic fermentation will produce a large amount of sludge and liquid biogas, which is difficult to handle later; aerobic composting requires a large area, and the electrical conductivity (EC) of the compost product is too high, that is, the salt content is too high, and it is difficult to use directly. Therefore, it is necessary to find a method that is more suitable for the resource utilization of food waste.

[0003] The method of using black soldier fly larvae to treat food waste can better transform food waste and recycle the nutrients in it. In addition, black soldier fly larvae have high nutritional value. The protein content in dried insects is as high as 32%-52%, which is similar to the protein content of soybean meal, and the crude fat content is as high as 31%-38%. At the same time, it is rich in essential elements for supporting the growth of plants and animals, as well as crude fiber, lauric acid, antibacterial substances and chitin, which can replace fish meal to feed economic animals such as poultry and fish. Black soldier flies also have the advantages of a stable growth cycle, inhibiting the growth of maggots in the substrate, and adults not invading the human living environment. Therefore, using black soldier fly larvae to treat food waste has extremely high feasibility and economic value. However, under the existing technology, after the black soldier fly larvae transform the food waste, they will form insect feces with high salt content, namely insect sand (EC value 10-20ms / cm), and its salt content is much higher than the requirement of compost products. Therefore, the insect sand cannot be applied directly to the soil, and auxiliary materials must be added and secondary composting must be carried out before it can be applied to the soil.

[0004] One of the reasons for this result is that one-time feeding or irregular feeding in batches makes it difficult for the larvae to process all the food waste in the early stage of transformation. The carbon and nitrogen elements in the food waste are quickly fermented before being eaten by the black soldier fly larvae and lost in the form of gas. The undigested food waste is mixed with the insect sand, and the larvae cannot feed efficiently. In addition, the large loss of carbon and nitrogen elements causes the quality of the food waste to decrease, and the concentration effect is obvious, resulting in a high salt content in the insect sand. In addition, one-time feeding will also lead to a large design capacity of the black soldier fly process, requiring a large amount of land area.

[0005] In view of this, it is necessary to improve the process of black soldier flies treating food waste, further reduce the salt content in the insect sand, and improve the conversion efficiency and scale of black soldier flies into food waste resources. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present application provides a method for reducing the salt content of insect sand in the process of converting food waste by black soldier flies. The present application uses a batch feeding method and separates the larvae and insect sand before adding food waste each time, thereby effectively avoiding the problem of excessive salt content of insect sand that cannot be recycled due to incomplete conversion, concentration effect, etc. The present application specifically adopts the following technical solutions.

[0007] Firstly, in order to achieve the above-mentioned purpose, a method for reducing the content of insect sand and salt in the process of converting food waste by black soldier flies is proposed, and the steps include: the first step: removing substances that are not easily bioconverted in the food waste, adjusting the moisture content of the food waste after removal to a range of 70-75%, and homogenizing the adjusted food waste to obtain feeding materials; the second step: proportioning the number of black soldier fly larvae according to the total weight of the feeding materials to be processed; the third step: inoculating the black soldier fly larvae into the food waste, extracting the feeding materials corresponding to the wet weight according to the preset feeding ratio of the corresponding day every day, feeding the black soldier fly larvae until the conversion is completed, and harvesting the larvae; wherein, in the third step, the black soldier fly larvae and the insect sand are separated before each feeding; the preset feeding ratio added every day is set as follows: in the process of the black soldier fly larvae growing from the young age to the middle age until the conversion is completed, the preset feeding ratio is first increased from a small amount and then decreased from a large amount.

[0008] Optionally, in any of the above methods for reducing the salt content of insect sand in the process of converting food waste by black soldier flies, the insect sand separated daily and the insect sand remaining after the conversion are concentrated and stored for composting.

[0009] Optionally, a method for reducing the insect sand and salt content in the process of black soldier fly conversion of food waste as described above, wherein the black soldier fly larvae are fed for a total of 7 days from the first inoculation of the black soldier fly larvae into the food waste to the end of the conversion, wherein the feeding ratio on the 4th day is set to the highest and the feeding ratio on the 7th day is set to the lowest.

[0010] Optionally, a method for reducing the insect sand salt content in the process of black soldier flies converting food waste as described above, wherein, in 7 days, the feeding ratio on the 1st day, the feeding ratio on the 6th day, and the feeding ratio on the 7th day are set in a first magnitude range; the feeding ratio on the 2nd day, the feeding ratio on the 3rd day, and the feeding ratio on the 5th day are set in a second magnitude range; wherein the feeding amount in the second magnitude range is greater than the feeding amount in the first magnitude range but less than the feeding amount on the fourth day.

[0011] Optionally, a method for reducing the insect sand salt content in the process of black soldier flies converting food waste as described above, wherein the feeding amount in the second magnitude interval is close to twice the feeding amount in the first magnitude interval; and the feeding amount on the fourth day is close to twice the feeding amount in the second magnitude interval.

[0012] Optionally, a method for reducing the insect sand salt content in the process of black soldier flies converting food waste as described above, wherein the feeding ratio on the first day, the feeding ratio on the sixth day, and the feeding ratio on the seventh day are set to be close to each other and gradually decrease.

[0013] Optionally, a method for reducing the insect sand salt content in the process of black soldier flies converting food waste as described above, wherein the preset feeding ratios for daily addition from the 1st day to the 7th day are 8.0%, 13.0%, 15.0%, 36.0%, 14.0%, 8.0% and 6.0% of the total amount of feed obtained in the first step, respectively.

[0014] Optionally, a method for reducing the insect sand and salt content in the process of converting food waste by black soldier flies as described above, wherein in the second step, the ratio of the number of black soldier fly larvae according to the total weight of the added feed to be treated is specifically: for every 1 kg of wet weight of the added feed, 1500 black soldier fly larvae that are hatched for 3-4 days are inoculated.

[0015] Optionally, a method for reducing the insect sand and salt content in the process of converting food waste by black soldier flies as described above, wherein the black soldier fly larvae and the food waste they are fed daily are always kept in a constant temperature and humidity chamber, maintaining the temperature at 28±1°C and the humidity at 70±2%.

[0016] Optionally, a method for reducing the salt content of insect sand in the process of converting food waste by black soldier flies as described above, wherein when the black soldier fly larvae and insect sand are separated before each feeding, they are first placed in an environment of 35-40°C to force the black soldier fly larvae to crawl out before separation.

[0017] Beneficial Effects

[0018] The method provided in the present application for reducing the salt content of insect sand in the process of converting kitchen waste by black soldier flies is to feed the black soldier fly larvae at different growth stages in batches according to different feeding ratios with the kitchen waste, and to separate the larvae and insect sand before each feeding of the kitchen waste, so as to effectively avoid the problem of excessive salt content of the insect sand caused by incomplete conversion, concentration effect and the like. At the same time, the present invention can also improve the efficiency of the black soldier fly larvae in processing kitchen waste and the larvae harvest. The present application feeds the larvae separated from the insect sand with kitchen waste every day, and the feeding amount each time is set according to the growth status of the black soldier fly larvae. After the conversion is completed, the kitchen waste is no longer fed. At this time, the insect sand is separated to obtain insect protein and insect sand, which are used for preparing feed and compost conversion respectively. Through the feeding strategy of batch feeding, the present application can reduce the salt content transferred to the insect sand during the black soldier fly transformation process by 43%, while increasing the harvest of black soldier fly larvae by 69% at the end of the transformation, and effectively improve the resource utilization efficiency of black soldier flies and the yield of insect protein, thereby increasing the daily processing capacity of black soldier fly transformation organic solid waste equipment.

[0019] The present invention makes full use of the fact that the conversion efficiency of black soldier fly larvae to food waste varies at different stages, and reduces the salt content of insect sand in the food waste resource process of black soldier fly larvae by feeding them in batches and increasing the frequency of insect sand separation. The present invention proposes for the first time to feed different amounts of food waste to black soldier fly larvae every day according to the food intake of black soldier fly larvae at different stages, thereby reducing the salt content transferred to the insect sand. The present invention overcomes the following problems existing in the prior art:

[0020] (1) The worm sand produced by the black soldier fly larvae in converting food waste has a high salt content, and the subsequent worm sand composting cost is high;

[0021] (2) One-time feeding results in excessive thickness of food waste, which limits the efficiency of black soldier fly larvae in converting food waste;

[0022] (3) One-time feeding results in a small daily processing capacity of the black soldier fly transformation facility or equipment.

[0023] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0025] Figure 1 This is a schematic flow chart of the steps of the method for reducing the insect sand salt content in the process of converting food waste by black soldier flies in the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose and technical solution of the embodiment of the present application clearer, the technical solution of the embodiment of the present application will be clearly and completely described in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, not all of the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0028] In the present invention, unless otherwise specified, the required materials are commercially available products well known to those skilled in the art or are obtained in a manner well known in the art.

[0029] In the present invention, the food waste preferably includes a mixture of food residues, processing waste and other wastes generated in the production and operation processes of the catering industry, unit catering, food processing, etc., and does not include inorganic waste such as bones or shells.

[0030] Figure 1 A method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies according to the present application comprises the following steps:

[0031] The first step is to remove the substances that are not easily biotransformed from the food waste, such as bones, plastics, shells, etc., adjust the moisture content of the food waste to a range of 70-75%, and homogenize the adjusted food waste to obtain feed;

[0032] Step 2: proportion the number of black soldier fly larvae according to the total weight of the feed to be treated;

[0033] Generally speaking, the insect-to-feed ratio in this step can be set to 1:1500, preferably using 1500 black soldier fly larvae that are hatched for 3-4 days and have a single larva weight of 5 mg to 10 mg (wet weight) to treat 1 kg of food waste (70% moisture content) in a 7-day growth period;

[0034] Step 3: Inoculate the black soldier fly larvae into the food waste, extract the corresponding wet weight of the feed according to the preset feeding ratio of the corresponding day, feed the black soldier fly larvae until the transformation is completed, and harvest the larvae and insect sand;

[0035] In the third step, the black soldier fly larvae and the insect sand are separated before each feeding;

[0036] The conversion cycle of black soldier fly larvae in treating food waste is controlled at 7 days, the temperature is 28±1℃, and the humidity is controlled at 70±2%. In the process of separating the insect sand, in order to avoid excessive stirring of the material to damage the insect body, the mixture of insect sand and larvae can be placed in an environment of 35-40℃ to force the black soldier fly larvae to actively separate from the insect sand.

[0037] The insect sand separated daily and the remaining insect sand after the transformation is completed can usually be stored together for composting;

[0038] The preset feeding ratio added daily is different from each other, and is generally set to: during the process of the black soldier fly larvae growing from the young stage to the middle stage until the transformation is completed, the preset feeding ratio is set to increase from a small amount first, and then decrease from a large amount.

[0039] Generally speaking, taking into account the feeding needs of black soldier fly larvae at different stages, the impact of the thickness of food waste accumulation on the insect body, and the efficiency of black soldier fly larvae in converting food waste after feeding, the present application generally sets the feeding ratio on the 4th day to the highest and the feeding ratio on the 7th day to the lowest during the feeding period from the first inoculation of the black soldier fly larvae into the food waste to the end of the conversion, and correspondingly sets the feeding ratio on the 1st day, the feeding ratio on the 6th day, and the feeding ratio on the 7th day in a lower first magnitude range, and sets the feeding ratio on the 2nd day, the feeding ratio on the 3rd day, and the feeding ratio on the 5th day in a higher second magnitude range.

[0040] Under a more preferred feeding method, the feeding amount in the second magnitude interval is generally set to be close to twice the feeding amount in the first magnitude interval; the feeding amount on the fourth day is set to be close to twice the feeding amount in the second magnitude interval, and the feeding ratio on the first day, the feeding ratio on the sixth day, and the feeding ratio on the seventh day are set to be close to each other and gradually decrease.

[0041] Embodiment 1:

[0042] The kitchen waste is collected from the restaurant, and the bones, paper towels, egg shells, etc. in the kitchen waste are removed, and the excess water is filtered out. Then, the kitchen waste is crushed and homogenized with a homogenizer, and the particle size is controlled between 4mm-10mm, and the moisture of the kitchen waste is controlled at 70%. 1kg of kitchen waste is taken for the experiment. The kitchen waste after pulping is inoculated with black soldier fly larvae 4 days after hatching, and the ratio of black soldier fly larvae to organic solid residue is 1500 / kg kitchen waste (wet weight), and is placed in a constant temperature and humidity chamber, maintaining the temperature at 28±1°C and the humidity at 70±2%. The batch feeding process. The daily addition amount of kitchen waste is 8.0%, 13.0%, 15.0%, 36.0%, 14.0%, 8.0%, and 6.0% of the total amount of kitchen waste treatment, respectively. That is to say, in the 7-day conversion cycle, the feeding amount of food waste is: 80g on the first day, 130g on the second day, 150g on the third day, 360g on the fourth day, 140g on the fifth day, 80g on the sixth day, and 60g on the seventh day. Before adding the feed, the temperature is maintained at 35°C by heating to force the black soldier fly larvae to crawl out and achieve the purpose of separating the insect sand. The conversion is completed on the 8th day, all the larvae are harvested, and all the insect sand is mixed evenly.

[0043] Comparative Example 1:

[0044] Kitchen waste was collected from restaurants, and the kitchen waste was removed, the moisture content was controlled, and the homogenization process was performed. 1 kg of kitchen waste was taken for the experiment. The pulped kitchen waste was inoculated with black soldier fly larvae 4 days after hatching. The ratio of black soldier fly larvae to organic solid residue was 1500 / kg kitchen waste (wet weight). It was placed in a constant temperature and humidity chamber, and the temperature was maintained at 28±1°C and the humidity was maintained at 70±2%. The kitchen waste was added at one time. The transformation was completed on the 8th day, all the larvae were harvested, and all the insect sand was mixed evenly.

[0045] Comparative Example 2:

[0046] Kitchen waste was collected from the restaurant, and the kitchen waste was removed, the moisture content was controlled, and the homogenization process was performed. 1 kg of kitchen waste was taken for the experiment. The pulped kitchen waste was inoculated with black soldier fly larvae 4 days after hatching. The ratio of black soldier fly larvae to organic solid residue was 1500 / kg kitchen waste (wet weight). It was placed in a constant temperature and humidity chamber, and the temperature was maintained at 28±1°C and the humidity was maintained at 70±2%. Kitchen waste was fed every day, and the daily feeding amount was about 143g. The transformation was completed on the 8th day, all larvae were harvested, and all the insect sand was mixed evenly.

[0047] The results corresponding to the above embodiments and comparative examples are shown in Table 1. It can be seen from the table that the conversion process provided by the present invention can effectively reduce the salt content in the insect sand, while improving the weight loss rate and conversion rate of food waste, and the harvest of larvae is also the largest, while daily quantitative feeding of food waste will affect the conversion process. This is because the early and late conversion efficiency of black soldier flies for resource-based food waste is low, and the food waste in the early and late stages of the conversion is not fully utilized, thus affecting the EC value and conversion effect of the insect sand.

[0048] Table 1 Related index parameters of examples and comparative examples

[0049]

[0050] In summary, the method of the present invention has the following advantages:

[0051] (1) It can effectively reduce the EC value in black soldier fly sand;

[0052] (2) Improve the conversion rate and larval production of food waste;

[0053] (3) Since the daily dosage is less than the one-time dosage, the processing scale of the existing black soldier fly resource-based kitchen waste facilities or equipment can be increased.

[0054] The above is only an implementation method of the present application, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application.

Claims

1. A method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies, It is characterized in that the steps include: The first step: removing the substances that are not easily bioconverted from the food waste, adjusting the moisture content of the removed food waste to a range of 70-75%, and homogenizing the adjusted food waste to obtain feed; Step 2: proportion the number of black soldier fly larvae according to the total weight of the feed to be treated; Step 3: Inoculate the black soldier fly larvae into the food waste, extract the corresponding wet weight of the feed according to the preset feeding ratio of the corresponding day, feed the black soldier fly larvae until the transformation is completed, and harvest the larvae; In the third step, the black soldier fly larvae and the insect sand are separated before each feeding; The preset feeding ratio added daily is set as follows: in the process of the black soldier fly larvae growing from the young stage to the middle stage until the transformation is completed, the preset feeding ratio first increases from a small amount and then decreases from a large amount.

2. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as claimed in claim 1, It is characterized in that The insect sand separated daily and the remaining insect sand after the transformation are also centrally stored for composting.

3. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as described in claims 1-2, It is characterized in that The feeding is carried out for 7 days from the first inoculation of the black soldier fly larvae into the kitchen waste to the completion of the conversion, wherein the feeding ratio on the 4th day is set to the highest, and the feeding ratio on the 7th day is set to the lowest.

4. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as claimed in claim 3, It is characterized in that In the 7 days, the feeding ratio on the 1st day, the feeding ratio on the 6th day, and the feeding ratio on the 7th day are set in the first magnitude range; the feeding ratio on the 2nd day, the feeding ratio on the 3rd day, and the feeding ratio on the 5th day are set in the second magnitude range; Among them, the feeding amount in the second magnitude interval is greater than the feeding amount in the first magnitude interval but less than the feeding amount on the fourth day.

5. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as claimed in claim 3, It is characterized in that The feeding amount in the second magnitude interval is nearly twice that in the first magnitude interval; The feeding amount on the fourth day was nearly twice that of the second level interval.

6. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as described in claims 3-5, It is characterized in that The feeding ratio on the first day, the feeding ratio on the sixth day, and the feeding ratio on the seventh day are set to be close to each other and gradually decrease.

7. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as claimed in claim 3, It is characterized in that The preset daily feeding ratios from the 1st day to the 7th day are 8.0%, 13.0%, 15.0%, 36.0%, 14.0%, 8.0% and 6.0% of the total amount of feed obtained in the first step, respectively.

8. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as described in claims 1-7, It is characterized in that In the second step, the ratio of the number of black soldier fly larvae is specifically as follows: 1500 black soldier fly larvae hatched for 3-4 days are inoculated for every 1 kg of wet weight of the feed.

9. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as claimed in claim 8, It is characterized in that The black soldier fly larvae and the food waste they were fed daily were always kept in a constant temperature and humidity chamber, maintaining the temperature at 28±1°C and the humidity at 70±2%.

10. The method for reducing the content of insect sand salt in the process of converting food waste by black soldier flies as described in claims 8-9, It is characterized in that Before each feeding, the black soldier fly larvae and insect sand are separated by first placing them in a 35-40°C environment to force the black soldier fly larvae to crawl out before separation.

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