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Purpose of composting

Flow to compost organic wastes

Organic waste is waste derived from animals and plants. For example, livestock manure, solid waste produced from the manufacturing process of food such as vegetable residue, brewing residue, fermentation residue, waste of fish and animal. Organic fertilizer is produced from organic waste by microorganisms. They decompose easily decomposable organic matter.
To speed up the process artificially is called composting and it is necessary to create an environment where microorganisms are easy to operate.
In general, composting is decomposition by aerobic microorganisms and aerobic fermentation.

Conditions necessary for aerobic fermentation

Aerobic fermentation is carried out by the activity of aerobic microorganisms.It is important to create and maintain conditions that aerobic microorganisms can be active. Aerobic microorganisms need air to breathe.
Nutrient source for activity of microorganisms is necessary. Moisture is also important. But breathability gets worse if moisture is too high and even if the moisture is too low, growth of microorganisms is suppressed so appropriate moisture adjustment is also necessary. Microorganisms involved in composting are activated at an ambient temperature of 30 ° C or higher and temperatures of 60 ° C or more are necessary for killing or inactivating pathogens, parasite eggs or weed seeds.
It is also related to the evaporation of moisture so it is required to control the temperature.

Aerobic microorganisms

Microorganisms for composting exist naturally in raw materials, air, livestock houses, etc.

Uniform air supply

Air (oxygen) is essential for aerobic microorganisms necessary for fermentation.
Because aerobic microorganisms oxidize by decomposing organic matter using air, generates fermentation heat by oxidation reaction and promotes evaporation of moisture.
In the composting process, 「1. Air flowing」 in the raw material is an important point.
Next, it is also important to 「2. Adjust proper moisture before composting treatment」「3. Continue proper airflow into raw materials」.
By regularly performing stirring and turning back, it makes uniform contact with the air and does not cause fermentation irregularity.
However, excessive stirring and turning down will lower the internal temperature and will slow down composting, so it is important to be proper.

Nutrition source

There are two kinds of Organic substances. One is organic substances which easily decomposed (easily decomposable organic substances) and another is organic substances which hardly decomposed (hardly decomposable organic substances). Most of the nutrient source of microorganisms is easily decomposable organic substances.
Livestock manure and others containing a lot of easily decomposable organic matter are rich in nutrients for microorganisms.

Appropriate water content

When moisture is too high, breathability is going bad, and even if the moisture is too low, the growth of microorganisms is suppressed, so appropriate water content adjustment is necessary. By appropriately maintaining the moisture of the raw material to be composted, it will shorten the processing time.

Appropriate temperature

Aerobic microorganisms oxidize by decompose organic matter using air and fermentation heat by oxidation reaction occurs.
As aerobic fermentation is promoted, the internal temperature rises above 60 degrees. As a result, moisture evaporates, pathogenic bacteria and weed seeds are killed and inactivated.
It is possible to maintain a stable fermentation condition by preventing the influence of the external environment and performing aeration at high temperature.

What are the merits of using compost?

By properly using organic fertilizer, we can stably increase production of crop by supplying nutrients to plants, improving the chemical, material, biological of the soil and increasing soil productivity.
Compost is a kind fertilizer for both plants and soil.
Chemical fertilizers are excellent as fertilizer components, but microorganisms in the soil are killed as organic matter is not supplied. When soil cultivation to make crumb structure by microorganisms is stopped, soil productivity declines, the plants become weak against diseases and pests, and need to use fungicides and insecticides.

Representative composting process facility

For composting facilities, there are two general methods, “Stacking method” deposited in a compost shed and “agitation method” using a machine for stirring.
Since there are two types of stirring methods, open type and closed type, there are three kinds of composting process. Stacking method, Open type stirring method, and a closed type stirring method.

Stacking method
(Composting shed)

It is a method of doing switchover with a shovel loader etc. and composting it by accumulation for a long time.

• Less initial investment
• Long-term processing required
• Large work area is required
• It is susceptible to temperature influences
• It is difficult to deal with odors

Open type stirring method
(Rotary, scoop stirring)

It is a method of stirring materials periodically and composting it while gradually moving it.

• Appropriate moisture adjustment is necessary
• Facilities such as concrete construction, building etc. are necessary other than machines
• It is susceptible to temperature influences
• It is difficult to deal with odors

Closed type stirring method
(Compo Fuji)

It is a method of putting the material into a thermally insulated cylindrical fermentation tank and composting it by blades and ventilation.

• High initial cost
• Installation space is small
• Easy to deal with odors
• The influence of the temperature is small