ILLUCENS

Field of the invention

The present invention relates to agricultural production. The method comprises the bioconversion of a broad range of agricultural (organic) wastes, including manure and litter, distillery stillage, brewer grains, grain wastes, unusable grains of different crops, slaughterhouse wastes, sugar industry wastes, various press cakes and meals, dairy wastes, food wastes, etc., using larvae of Hermetia illucens.

Background of the Invention

Black soldier fly {Hermetia illucens ) is highly efficient in bioconverting various organic wastes and is widely used to treat agricultural wastes. A fly larva is capable to eat almost any biowastes, including manure and litter, distillery stillage, brewer grains, grain wastes, unusable grains of different crops, slaughterhouse wastes, sugar industry wastes, various press cakes and meals, dairy wastes, food wastes, etc. Due to the digestive specificities, the larvae of Hermetia illucens flies, in contrast to the false stable fly larvae, can digest substrates with a high cellulose content, thereby allowing them to treat feed substrates with a high cellulose content.

Another advantage of Hermetia illucens larvae is that they have up to 40% of amino acids which are beneficial for the growth and development of farm livestock, thus allowing the usage of dry larvae of Hermetia illucens as feed supplements for farm livestock and aquacultures.

Various methods, systems, and devices based on the process of bioconversion of organic wastes by larvae of Hermetia illucens are known. For instance, PCT/CN2016/111450 (published on 12.10.2017) describes the device for treating kitchen waste, e.g., from a restaurant, wherein the waste is treated by larvae of Hermetia illucens, then the adult larvae are used as a livestock feed, and the waste treated by these larvae is used as a fertilizer.

Typically, the aim of the prior art solutions is to make the organic waste treatment with the Hermetia illucens larvae more efficient, which is achieved by automating this process, providing beneficial conditions at each step of the insect metamorphosis, stimulating fly breeding, and changing a composition of organic waste to be treated.

In the prior art, there is still a need in an efficient method for treating organic wastes to produce a maximum biomass yield. However, the treatment of organic wastes with Hermetia illucens larvae by the prior art methods is accompanied with the following problems. The biomass yield of larvae differs according to a type of organic wastes to be treated with larvae. This difference can occur due to the different bulk density, nutritive value, nutrient ratio (proteins, fats, carbohydrates), grain size distribution, etc. of a substrate to be treated with larvae. For instance, in the prior art it is known RU 2390126 C2 (published on 27.05.2010) and CN 104844288 (published on 19.08.2015) disclosing methods for treating specific organic wastes, in which to achieve the maximum biomass yield of larvae, characteristics and compositions of a waste to be treated are taken into account. Typically, such methods are very specific and can't provide a high biomass yield when other types of substrates are used. Therefore, there is a need in a versatile method that can provide a maximum biomass yield of larvae per 1 kg of a treated substrate for different types of organic wastes.

Also, the separation of larvae from compost at the end of the waste treatment process is associated with several issues. For instance, in US 9,642,344 the larvae are separated from the compost by means of the migration thereof, i.e., the larvae are on the move and fall into the larvae harvesting receptacle. However, when moving actively, larvae are dehydrated and consume reserved nutrients, as a result decreasing a part of the biomass. Accordingly, the mechanical separation of larvae at the treatment stage when larvae have the maximum biomass would be most effective. In this case, the successful mechanical separation of larvae requires the linear size of larvae at the final stage of the treatment process to be more than the size of a fraction of a substrate to be treated. Moreover, the high moisture level in a feed substrate at the final stage of the treatment process can impede the separation of the obtained biomass from compost. In this way, there is a need in a method for treating organic wastes with larvae of Hermetia illucens which will allow the effective separation of larvae having the maximum biomass from compost produced from the treatment process.

The present invention discloses a method for treating organic wastes with larvae of Hermetia illucens which allows the quick and low-cost treatment of a wide range of organic wastes providing a high yield of larvae biomass with a maximum level of protein, excluding the above-mentioned disadvantages.

Brief disclosure of the invention

The present invention relates to a method for treating organic wastes, comprising stages of providing eggs of Hermetia illucens flies, incubating the eggs and growing larvae on a growth medium; further separating the larvae from the growth medium and sizing thereof; homogenizing organic wastes to produce a substrate having a moisture level of 70-55%; populating the substrate with larvae of the same size and a predetermined density, and bioconverting the substrate. One of the subject-matters of the invention is a method for producing a protein feed. The method comprises the following stages: producing eggs of Hermetia illucens flies, incubating the eggs and growing larvae on a growth medium; further separating the larvae from the growth medium and sizing thereof; homogenizing organic wastes to produce a substrate having a moisture level of 70-55%; populating the substrate with larvae of the same size and a predetermined density; bioconverting the substrate; separating the larvae from a produced compost; and heat treating the larvae.

In addition, one of the subject-matters of the invention is a protein product produced by the method disclosed above.

According to one of the embodiments of the invention, the growth medium for larvae growing is a grain nutrient mixture.

According to one of the embodiments of the invention, the growth medium for larvae growing is a mixture of crushed wheat and feed yeasts.

According to one of the embodiments of the invention, the moisture level of the growth medium is 65%.

According to one of the embodiments of the invention, the organic wastes are farm animal manure, or poultry waste, or a mixture of poultry waste and straw, or distillery stillage, or brewer grains, or grain wastes, or brans, or unusable crop grains, or a press cake, or meal, or domestic sludge, or food wastes.

According to one of the embodiments of the invention, eggs are incubated during 1-4 days.

According to one of the embodiments of the invention, the larvae are grown on the growth medium during 7-10 days.

According to one of the embodiments of the invention, the larvae are grown on the growth medium up to the larvae size of 4-7 mm.

According to one of the embodiments of the invention, the moisture level of the substrate is 60-65%.

According to one of the embodiments of the invention, the substrate is populated with larvae having a liner size of 4-7 mm.

According to one of the embodiments of the invention, the substrate is populated with larvae having a mass of 6-10 mg.

According to one of the embodiments of the invention, the substrate is populated with larvae at a density of 2.5-5.0 indiv/cm ² .

According to one of the embodiments of the invention, the substrate is bioconverted during 7-14 days. According to one of the embodiments of the invention, the larvae are separated from compost with the use of a sieve.

Details of one or more embodiments of the present invention are described below. Other features and advantages of the invention will be understood upon reading the disclosure and accompanying claims of the invention.

Detailed disclosure of the invention

In the method for treating organic wastes according to the present invention, larvae of Hermetia illucens were used. The life cycle of Hermetia illucens (from an egg to an egg) is about 40 days. At an adult stage a Hermetia illucens fly doesn't eat, and for successful breeding, it requires only a source of water and light having a spectrum close to natural light.

On the second day of the emerging, flies start mating, and 2 more days later they start laying their eggs.

In accordance with the inventive method, on an every day basis eggs were removed from an egg cell, weighed and placed in an incubator onto a specially arranged nutrient mixture to incubate thereof for 1-4 days and further grow larvae up to 4-7 mm for 7-10 days. The ratio between eggs and the nutrient mixture was lg of eggs per 0.15kg of the mixture. As the growth medium for growing the larvae a mixture of crushed wheat and feed yeasts (5-7%) was used. The moisture level of the mixture was 65%. Other corps can be used to prepare the growth medium.

After 7-10 days from the incubation start, the larvae were separated from the nutrient mixture and the larvae mass was sized. For this, the larvae mass together with the nutrient mixture was passed through a soil sieve column with a set of sieves having the following mesh: 1.5mm, 2.5mm, 4mm. The sieve of 4mm mesh was used to separate coarse particles of the treated nutrient mixture (a crust or lumps). The sieve of 2.5mm mesh was used to separate the larvae of more than 7mm (length) which had been employed for laboratory applications, including the sectioning application. The sieve of 1.5mm mesh was used to separate the biomass of "planting" larvae intended for populating the feed substrate for further treatment thereof. The treated nutrient mixture together with the biomass of larvae of no less than 4mm long was passed through the sieve of 1.5mm mesh. These larvae were overfed, and after 2-3 days the larvae were further separated via the soil sieve column.

A feed substrate was previously prepared from treated organic wastes by grinding and homogenizing various organic wastes. The moisture level of the feed substrate was maintained within the range of 65 to 80%. It is known that feed substrates have different bulk density, nutritive value, nutrient ratio (proteins, fats, carbohydrates), grain size distribution, etc. To balance and enrich the feed substrate to increase the nutritional value of the feed substrate, it is possible to mix low nutritional feed substrates (straw, beetroot pulp, manure and litter with bed, brewer grains, etc.) with highly nutritional substrates (feed yeasts, ground grain, molasses, sunflower meal, etc.). In addition, most food wastes have a high initial moisture level of more than 80%. An optimal moisture level for larvae activity is 60-70%. The high moisture level of feed substrates decreases the nutritional value. The excess of moisture can be separated in several ways: the pressing out and dilution with a dry carrier. Together with the excess moisture, water-soluble substances, proteins and sugars, are pressed out too and additional runoffs are generated. To balance the moisture level in the feed substrate it is practical to use water-retaining and structural components: brans, beetroot pulp, etc. Owing to the homogenization of the feed substrate and the control of the moisture level during the treatment process, the larvae biomass is separated from the compost by passing it through a sieve, thus, simplifying the structural design of the system and structurizing the compost.

After the separation, the larvae were weighed to determine the number thereof. "Planting larvae" with an individual mass of 6-10 mg were populated onto a feed substrate with a density of 2.5-5 indiv/cm ² . The population density depends on a type of a feed substrate and is calculated experimentally. The feed substrate was housed in piled plastic containers. A feed substrate layer thickness was about 10 cm. The higher thickness of the substrate layer gives rise to the creation of anaerobic zones, inefficient usage of the feed substrate and space, and increased gas discharge.

The bioconversion was finished at the maximum larvae mass. The average mass of one larva of Hermetia illucens on nutritional substrates was 200 mg. In general, the bioconversion of organic wastes was conducted from 7 to 14 days depending on the feed substrate and environmental conditions. Due to microbiological processes, the temperature of the feed substrate can increase up to 50°C at the room temperature 20°C.

At the end of the bioconversion, the moisture level of the treated feed substrate (compost) was less than 30%. The larvae biomass was separated from the compost by a vibrating screen (with a mesh of 4 mm). The resulted compost was packed to use it subsequently as a fertilizer.

To produce a nutritional protein feed, larvae with a moisture level of 70% in accordance with the inventive method were separated from the compost and dried at 90°C.

Results of the bioconversion of various organic wastes with larvae of Hermetia illucens are shown in Table 1 of Fig. 1.

According to the data shown in Table 1, it is clear that the method for treating organic wastes with larvae of Hermetia illucens according to the present invention allows the effective treatment of the broad range of organic wastes, as evidenced by the high and accepted conversion rate for all presented substrates. Although there are low conversion rates for some feed substrates, such rates are typical for substrates with a high level of plant biopolymers, which generally indicates that such substrates are possible to be treated. In this way, the low conversion of such substrates is also indicative of the high efficiency of the claimed method of organic waste treatment. Table 1 also shows that a high biomass yield on a dry matter is typical for all substrates.

The inventors have surprisingly found that the high biomass yield and high conversion of various feed substrates can be achieved by populating a substrate with larvae of the same size and a pre-defined density which, depending on a type of treated wastes, can vary within the range from 2.5 to 5 indiv/cm ² or from 3 to 5 indiv/cm ² . The stage of larvae separation which follows stages of incubation and growth allows calculating the required amount of larvae for populating a specific feed substrate (indiv/cm ² ) which is defined experimentally. This is associated with the fact that egg incubation takes more time, resulting in that after the incubation and growth stages a mixture of larvae of different sizes is obtained, which makes it difficult to quantify the planting larvae and can result in wasting the larvae, as well as in wrong predictions of biomass yield, incomplete treatment of a substrate and inefficient usage thereof. To size the planting larvae a method of sieving on a soil (or other) sieve column, both manual, and electrically actuated, is used. This allows obtaining larvae of different size groups which can be quantified. Moreover, during the treatment of wastes, the larvae of the same size rich the maximum size approximately simultaneously and have an individual mass that doesn't vary considerably, which is important at the stage of separation of the compost from the larvae.

Therefore, the claimed method achieves the balance between the feed substrate mass, planting larvae amount and mass, as well as the occupied area. In addition, the balance between the yielded average individual mass of the larvae, the larvae planting density (planting material usage) and the biomass yield per a substrate unit is achieved. This balance with all organic wastes allows a high rate of waste conversion and biomass yield. In addition, the claimed method makes it possible to finish the process exactly when the larvae get the maximum mass. The low moisture level of the compost together with larvae linear dimensions achieved at the end of the treatment stage of the method according to the present invention enable the separation of the larvae from the compost using a sieve.

It should be understood that different modifications of the present invention a person skilled in the art may come up with are within the scope of the accompanying claims of the present invention. All embodiments disclosed herein, which achieve the technical effect of the present invention, haven’t been demonstrated with all details. Although the present invention has been described with references to specific details, and it is not assumed that such details have to be considered as limiting the scope of the present invention, except and to the extent they are integrated into the appended claims.