JP7553016B2 - How to treat organic waste - Google Patents

Description

One embodiment of the present invention relates to a method for treating organic waste, more specifically, a method for treating organic waste using the larvae of insects such as houseflies.

As livestock farming expands, large amounts of livestock waste are generated, causing odors and water pollution. In order to properly manage and effectively use livestock waste in accordance with the Livestock Waste Law, composting and methane fermentation processes are carried out. However, it is difficult to efficiently carry out processing to effectively use livestock waste (hereinafter referred to as "effective processing") in a short period of time, and livestock farmers are burdened with the processing of livestock waste. To reduce this burden, Patent Document 1 discloses an insect bioprocessing system that can render organic waste, such as livestock manure, harmless or less harmful by feeding the larvae of insects to the organic waste.

JP 2002-11440 A

In a technology for treating organic waste using the larvae of insects such as houseflies, in order to efficiently treat the organic waste and to efficiently recover the larvae that have been treated for the organic waste, it is necessary to promote the growth of the larvae and raise them in better conditions that minimize the deaths of the larvae. One embodiment of the present invention aims to provide a method for treating organic waste that can raise the larvae while increasing their survival rate. Another embodiment of the present invention aims to provide a method for treating organic waste that can raise the larvae while increasing their growth rate.

In one embodiment of the present invention, a method for treating organic waste involves inoculating a feeding area containing organic waste with insect eggs, raising larvae that hatch from the insect eggs in the feeding area using the organic waste as food, and fermenting the organic waste before inoculating the insect eggs.

In the organic waste treatment method according to one embodiment of the present invention, the organic waste may be spread on a tray to form a feeding area. Alternatively, the larvae may be moved from the feeding area to a larvae collection section before they develop into pupae, and any remaining material on the tray may be collected.

According to the organic waste treatment method of one embodiment of the present invention, it is possible to prevent the temperature of the feeding area from rising, improve the growth environment for insect larvae, and increase the survival rate of the larvae. Furthermore, according to the organic waste treatment method of one embodiment of the present invention, since the organic waste is decomposed by microorganisms or enzymes, it is possible to make the food easier for the larvae to prey on, and the growth rate of the larvae can be increased. As a result, it becomes possible to collect more larvae.

1 is a flowchart of a method for treating organic waste according to one embodiment of the present invention. FIG. 1 is a schematic diagram illustrating a method for treating organic waste according to one embodiment of the present invention. 1 is a graph showing an example of the relationship between the process and temperature in an organic waste treatment method according to an embodiment of the present invention.

Each embodiment of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in various forms without departing from the spirit of the invention, and should not be interpreted as being limited to the description of the embodiments exemplified below.

In order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but this is merely an example and does not limit the interpretation of the present invention. In this specification and each figure, elements having the same function as those explained in the previous figures may be given the same reference numerals and duplicate explanations may be omitted.

First Embodiment
[Method of treating organic waste]
In this embodiment, a method for treating organic waste using the larvae of insects such as houseflies will be described. In the method for treating organic waste, the larvae of insects such as houseflies are fed with the organic waste, and the organic waste is decomposed to produce a fertilizer material, and the larvae are collected and can be used as an animal protein source, for example, as feed. In the following description, the housefly is used as an example of the insect larvae, but in addition to the housefly, insects belonging to the order Diptera, such as flesh flies and water flies, can also be used.

Figure 1 is a flow chart showing the flow of the organic waste treatment method according to this embodiment. Figure 2 is a schematic diagram explaining the organic waste treatment method according to this embodiment. Below, an example of the organic waste treatment method according to this embodiment will be explained with reference to Figures 1 and 2.

First, organic waste is prepared (S101). The organic waste in this embodiment includes at least one of livestock manure, food waste, and agricultural waste. Livestock manure includes, for example, cow manure, pig manure, bird manure, and insect manure. Food waste includes, for example, vegetable waste, tofu waste, and soybean pulp. When the organic waste is livestock manure, wheat bran, skim milk powder, rice bran, dried soybean pulp, and other additives with long shelf life and nutritional value, or the above-mentioned food waste, may be added to promote the fermentation process described below. When the organic waste is food waste or agricultural waste, the organic waste may be crushed so that the size of the solid matter contained in the organic waste is, for example, chip-like or granular, within a range of 10 mm square or less. Alternatively, the food waste may be in the form of a paste. If the size of the solid matter is too large, the fermentation process of the organic waste described below does not proceed easily, or it is difficult for the larvae to eat, so that it may take a long time to process the organic waste. If the size of the solids is too small, adequate gaps cannot be formed for the larvae to move around, and moisture will be released, making it necessary to adjust the moisture content of the organic waste. By adjusting the size of the solids contained in the organic waste to within the above range, the efficiency of the fermentation treatment of the organic waste can be improved, and the efficiency of the treatment of the organic waste can be improved.

Additives such as rice husks, sawdust, sawdust powder, perlite, and charcoal may be added to the organic waste to adjust the moisture content and promote the aerobic fermentation process described below. For example, wood charcoal, bamboo charcoal, and charcoal-smoked rice husks may be used as charcoal. It is preferable to appropriately adjust the additives added to the organic waste so that the moisture content of the medium is in the range of 65 wt% to 70 wt%. Adding these additives has the effects of acting as a carrier for microorganisms, maintaining space, adjusting moisture, and deodorizing, and can improve the efficiency of the fermentation process of the organic waste, and can improve the efficiency of the treatment of the organic waste. Additives may be added to the organic waste. Examples of additives include, but are not limited to, pH adjusters and viscosity adjusters.

Microorganisms or enzymes may be added to the organic waste to promote the fermentation process described below. Examples of microorganisms that may be used include lactic acid bacteria, koji mold, and yeast. When the organic waste is food waste, it is preferable to add lactic acid bacteria. By adding microorganisms or enzymes to the food waste, the fermentation process of the organic waste can be carried out efficiently.

Organic waste to which additives, microorganisms, enzymes, etc. have been added can be prepared by adding additional water if necessary and stirring and mixing.

Next, the prepared organic waste is fermented (S103). In the organic waste treatment method according to this embodiment, a preliminary fermentation process is performed on the organic waste to be used as food for insect larvae. The fermentation process of the organic waste may be performed under aerobic conditions or under anaerobic conditions. Also, after the fermentation process is performed under anaerobic conditions, the fermentation process may be performed under aerobic conditions. If the organic waste is livestock manure, it may be fermented under anaerobic conditions since it already contains anaerobic bacteria. If the organic waste is food waste, it is preferable to ferment it by adding microorganisms or enzymes rather than natural fermentation, and it is particularly preferable to ferment it by adding lactic acid bacteria.

When aerobic fermentation is performed, the temperature of the organic waste during fermentation is preferably in the range of 50°C to 70°C. It is preferable to feed air into the organic waste during fermentation, for example, by stirring the organic waste every 12 hours. The degree of fermentation can be determined by measuring the temperature and moisture content of the organic waste during fermentation. For example, when the organic waste is livestock manure, it is preferable to perform the fermentation process for 24 hours to 120 hours, or 48 hours to 72 hours, within the temperature and humidity ranges described above.

An example of anaerobic fermentation is methane fermentation. When anaerobic fermentation is performed, the temperature of the organic waste during fermentation is preferably in the range of 26°C to 65°C. The organic waste during fermentation is preferably sealed in a container to prevent air from entering or leaving. The degree of fermentation can be determined by measuring the temperature, pH, elapsed time after the organic waste is added, and moisture content of the organic waste during fermentation. For example, when the organic waste is livestock manure, it is preferable to perform the fermentation process for 14 to 60 days, or 30 to 45 days after the organic waste is added, with the pH set to 6 to 9, or 6.8 to 7.6, within the temperature and humidity ranges described above.

It is possible that the larvae do not directly prey on solid matter, but rather break down solid matter with digestive enzymes that they excrete, and then prey on the decomposed matter. In the organic waste treatment method according to this embodiment, the organic waste used as food for the larvae is subjected to a fermentation treatment in advance, so that it is decomposed (fermented) by microorganisms. The decomposed organic waste is easier for the larvae to prey on, and it is possible to increase the amount of prey that the larvae can prey on. As a result, the survival rate and growth rate of the larvae can be increased. In addition, the amount of organic waste effectively treated by the larvae can be increased.

Next, the feeding area is formed using the organic waste that has been fermented (S105). As shown in FIG. 2, the feeding area 10 according to this embodiment is formed by spreading the organic waste 130 on the tray 110. It is preferable that the organic waste 130 is spread evenly on the tray 110 with a uniform thickness. The thickness of the organic waste 130 may be, for example, in the range of 30 mm to 80 mm. It is preferable that the thickness of the organic waste 130 is, for example, about 60 mm. By stirring and mixing the organic waste 130, an appropriate gap is formed in the feeding area 10 through which the larvae 150 can move. The prepared organic waste may be spread on the tray and fermentation may be performed on the tray 110. In this case, the step of forming the feeding area (S105) and the step of performing the fermentation process (S103) may be interchanged.

Next, the feeding area is inoculated with insect eggs (S107). The insect eggs are inoculated on the surface of the organic waste 130 of the feeding area 10. It is not necessary to inoculate the insect eggs uniformly over the entire surface of the organic waste 130, but multiple insect eggs may be inoculated in multiple locations in the form of egg masses. By inoculating the insect eggs in the form of egg masses, it is possible to approximate the egg-laying state in the natural world, improve the egg hatching rate, and improve the survival rate of the larvae. It is preferable that the weight ratio of the insect eggs to be inoculated is more than 0 and 0.1% by weight or less when the organic waste is 100%. If the weight ratio of the insect eggs to be inoculated is large, the food for the hatched larvae may be insufficient, and the growth of the larvae may be delayed. If the weight ratio of the insect eggs to be inoculated is small, the organic waste, which is the food for the larvae, will be left over, and the organic waste cannot be efficiently and effectively treated. By inoculating the insect eggs within the above range, the number of larvae 150 per unit weight of organic waste 130 can be controlled, and as a result, the organic waste can be effectively treated and the larvae can be raised efficiently. Note that it is preferable to confirm that the fermentation process is complete before inoculating the insect eggs.

Next, the larvae hatched from the insect eggs are raised in the feeding area (S109). The eggs inoculated in the feeding area hatch in about half a day. In the organic waste treatment method according to the present embodiment, the larvae hatched from the insect eggs are raised using fermented organic waste as food. The fermented organic waste has already been decomposed by microorganisms or enzymes, making it easier for the larvae to prey on and digest, and the larvae can be raised efficiently. In addition, since no fermentation of the organic waste occurs, it is possible to prevent the feeding area from becoming too hot. The temperature of the organic waste during larvae cultivation is preferably in the range of 30°C to 37°C. The moisture content of the organic waste during larvae cultivation is preferably in the range of 65 wt% to 70 wt%. If the temperature and moisture content of the organic waste during larvae cultivation are outside the above ranges, the egg hatching rate, larvae growth, and survival rate may decrease. It is preferable not to stir or stimulate the organic waste during larvae cultivation. By controlling the temperature and moisture content of the organic waste during larval development, it is possible to increase the amount of organic waste that the larvae consume, thereby increasing the survival rate and growth rate of the larvae.

Next, the larvae raised in the feeding area are separated from the organic waste residue (decomposition product) (S111). The larvae and the residue utilize the dispersal habit (peristaltic dispersal habit) of the larvae when they metamorphose into pupae (about 7 days after hatching). As shown in FIG. 2, the tray 110 of the feeding area 10 in this embodiment has a side wall surrounding the organic waste 130, and at least one side wall surface 111 of the side wall is inclined obliquely. A larvae collection section 170 with an open upper surface is disposed below the edge of the obliquely inclined wall surface 111. The obliquely inclined wall surface 111 has a slit-shaped groove 113. The larvae 150 in the organic waste 130 actively disperse in search of a place to pupate, and move up the obliquely inclined wall surface 111 along the groove 113 and to the edge. The larvae 150 that have fallen from the edge of the wall surface 111 are moved to the larvae collection section 170. The larvae collection section 170 may be, for example, a box or a shallow tank filled with water. In the organic waste treatment method according to this embodiment, the larvae 150 can be raised in conditions suitable for the growth of the larvae, and the larvae 150 can be efficiently collected in the larvae collection section 170. Therefore, the larvae 150 raised in the feeding area 10 can be efficiently separated from the remaining (decomposed) organic waste 130.

The separated larvae and the organic waste residue are collected separately (S113). The larvae collected in the organic waste treatment method according to this embodiment can have an improved weight per unit weight and can increase the survival rate and growth rate of the larvae because the feeding ground is suitable for the growth of the larvae. The larvae move more actively, so the recovery efficiency from the feeding ground can be improved. As a result, the amount of larvae collected per 100% of the organic waste can be improved. The collected larvae can be used as a source of animal protein, for example, as feed. The organic waste residue collected is the organic decomposition product of the organic waste eaten by the larvae and excreted. In the organic waste treatment method according to this embodiment, the larvae 150 can be raised in a feeding ground suitable for the growth of the larvae, so the amount of leftover food per unit weight of the collected organic waste residue can be reduced. The collected organic waste residue can be subjected to a heat drying process at 50°C to 70°C to stop the growth of the remaining larvae and pupae and reduce the moisture content. As a result, the organic waste residue can be used as a feed ingredient or fertilizer ingredient.

In the organic waste treatment method according to this embodiment, larvae hatched from insect eggs are raised using fermented organic waste as food, allowing the larvae to be raised in an environment suitable for growth. As a result, it is possible to increase the growth rate and survival rate of the larvae. In addition, since many fully grown larvae feed on the organic waste, the amount of food consumed by the larvae increases, allowing the organic waste to be efficiently and effectively treated, and the amount of organic waste that can be used as a source of fertilizer or feed can be increased.

Figure 3 shows an example of the relationship between each process of fermentation, egg inoculation, and larvae rearing in the organic waste treatment method according to this embodiment and the temperature of the organic waste. First, when the fermentation treatment (S103) of the organic waste is started at time t1, the temperature of the organic waste rises from T1 to T2 due to fermentation. When the fermentation treatment ends at time t2, the temperature of the organic waste returns from T2 to T1. Note that if the temperature of the culture medium is not suitable for fermentation due to the influence of the outside air temperature, for example, below 20°C or above 50°C, the organic waste may be intentionally heated or cooled during the fermentation treatment to promote fermentation.

The temperature T2 during fermentation is higher than the appropriate temperature for insect eggs and larvae to survive, and they are likely to die, so it is not preferable to inoculate insect eggs or raise larvae at this stage. After the fermented organic waste has cooled to an appropriate temperature for insects, for example at time t2, insect eggs are inoculated (S105). After a predetermined time has passed (for example, time t3 shown in Figure 3), the eggs inoculated into the organic waste hatch and become larvae. The larvae grow by repeatedly consuming and excreting the fermented organic waste (S107). Note that if the temperature of the medium is not suitable for larval growth due to the influence of the outside air temperature, for example below 30°C or above 40°C, the organic waste may be intentionally heated or cooled to promote larval growth.

In this way, in the organic waste treatment method according to this embodiment, the fermentation treatment of the organic waste (S103) and the inoculation of insect eggs (S105) and rearing of larvae (S105) are carried out separately, so that the organic waste can be treated at a temperature suitable for each process. As a result, the organic waste can be effectively treated efficiently, and the larvae can be efficiently reared.

An organic waste treatment method according to one embodiment of the present invention was used to effectively treat livestock manure. The results are described in the following examples.

[Example 1]
In Example 1, 3.6 kg of tofu scraps, which is organic waste, was mixed with 840 g of dried soybean pulp and 440 g of rice husks as additives. The organic waste was then naturally fermented at room temperature under aerobic conditions for 5 days. The maximum temperature during fermentation was 55°C. The moisture content was 72.3 wt%. When the temperature reached 37°C or lower, 2.0 g of housefly eggs were inoculated, and larvae were raised at a temperature of 28°C to 44°C.

After four days, the grown larvae began to move from the feeding area to the larvae collection area, and after eight days, the effective treatment of the organic waste was completed. At this point, the remaining organic waste was 1.06 kg, the collected larvae were 455 g, the average weight of 100 larvae was 1.85 g, and the total number of larvae obtained by dividing the total weight of the larvae by the average weight of 100 larvae was approximately 24,600. The results of Example 1 are shown in Table 1.

[Comparative Example 1]
In Comparative Example 1, larvae were raised under the same conditions as in Example 1, except that natural fermentation of organic waste was not carried out.

After 4 days, the grown larvae began to move from the feeding area to the larvae collection area, and after 8 days, the effective treatment of the organic waste was completed. At this time, the remaining organic waste was 0.865 kg, the collected larvae were 318 g, the average weight of 100 larvae was 1.63 g, and the total number of larvae divided by the average weight of 100 larvae was about 19,500. The results of Comparative Example 1 are shown in Table 1. In the comparative example, the organic waste fermented from the first day, and the maximum temperature rose to about 55 ° C. In addition, the temperature of the organic waste was 35 ° C. or higher from the first day to the third day. As a result, the moisture in the medium evaporated, and the weight of the remaining organic waste was reduced compared to Example 1.

In this embodiment, the growth rate of the larvae (weight of 100 larvae) was improved by using pre-fermented organic waste as food for the larvae. In addition, because it is possible to prevent the temperature from rising in the feeding area, the survival rate (total number) of the larvae was improved. As a result, it can be seen that the total weight of the larvae increased.

Anything that a person skilled in the art may add, remove, or modify components as appropriate based on the above-described embodiment of the present invention is also included in the scope of the present invention as long as it contains the essence of the present invention.

Even if there are other effects and advantages different from those brought about by the above-mentioned embodiments, those which are clear from the description in this specification or which can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

Claims (15)

A method for treating organic waste using insects belonging to the order Diptera, comprising the steps of:
A first step of crushing solid matter contained in organic waste into a predetermined size range that is easy for the insects to prey on;
A second step of fermenting the organic waste;
A third step of inoculating the insect eggs into a feeding site containing the organic waste after the second step ;
A fourth step of raising larvae hatched from the eggs in the feeding area using the organic waste as food.
A method for treating organic waste comprising the steps of: 2. The method for treating organic waste according to claim 1, wherein the solid matter is pulverized into chips or granules having a size of 10 mm square or less. 3. The method for treating organic waste according to claim 1 or 2, further comprising the step of spreading the fermented organic waste to a thickness of 30 mm or more and 80 mm or less after the second step to form a feeding area for the third step. 4. The method for treating organic waste according to claim 1, wherein the fermentation treatment is carried out under aerobic conditions. 4. The method for treating organic waste according to claim 1 , wherein the fermentation treatment is carried out under anaerobic conditions. 6. The method for treating organic waste according to claim 5, wherein the fermentation treatment is carried out at a pH of 6 to 9. 7. The method for treating organic waste according to claim 1, wherein microorganisms are added during the fermentation treatment. 8. The method for treating organic waste according to claim 7 , wherein the microorganism is selected from the group consisting of lactic acid bacteria, koji mold, and yeast. 7. The method for treating organic waste according to claim 1, wherein an enzyme is added during the fermentation treatment. 10. The method for treating organic waste according to claim 1, wherein the larvae are raised at a temperature of the organic waste of 30°C or higher and 37°C or lower. 11. The method for treating organic waste according to claim 1, wherein the larvae are raised in an environment where the moisture content of the organic waste is 65 wt % or more and 70 wt % or less. 12. The method for treating organic waste according to claim 1 , wherein the insect is a house fly. The method for treating organic waste according to claim 1 , wherein the organic waste contains a pH adjuster as an additive. The method for treating organic waste according to claim 1 , wherein the organic waste contains a viscosity modifier as an additive. 15. The method for treating organic waste according to claim 1, wherein the insect eggs are inoculated in the form of egg masses at multiple locations on the surface of the organic waste.

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