Composting | Factors Affecting Composting Process

Composting

Composting is the method of aerobic or anaerobic decomposition of organic waste through a biological process, converting waste into harmless compound called compost.

Compost is widely used as manure for growing the crops because it is rich in nitrogen content. Due to composting, the volume of refuse is very much reduced (50-60%) and resulting matter can be safely handled since it becomes free from pathogenic organisms. Composting is the best disposal method for developing countries as refuses contains large amount of organic matter.

Factors affecting composting

1. Organisms

Aerobic composting is a dynamic system where in bacteria actinomycetes, fungi and other bacterial form are actively involved. Thermophillic bacteria are mainly responsible for the breakdown of proteins and other readily biodegradable organic matter.

2. Use of external culture

If the solid waste do not have required bacterial pollution, it is necessary to add external culture like night soil, cow dung, etc. which contain active microorganisms. Addition of such culture also affects composting process.

3. Moisture

When the moisture content is too low, the metabolic activity of microorganisms reduces, whereas if the moisture content were too high, anaerobic condition would setup. Hence for better composting process the moisture contain should be optimum. The moisture content should be maintained in the range of 60-60%

4. Temperature

During aerobic process, a large amount of heat is released and temperature rises to 70°C. Such rise in temperature results in the destruction of parasites and pathogens. But when temperature is greater than 50°C, large amount of nitrogen gets lose which is necessary for building the cell structure of microorganisms.

5. C/N Ratio

Composting process greatly affected by C/N ratio. Microorganisms utilize the carbon as sources of energy while nitrogen for building the cell structure. More amount of carbon is needed than nitrogen. It has been observed that the microorganisms utilize about 30% part of carbon for each part of nitrogen. Therefore C/N ratio of 30% would be most favourable for rapid composting. It has been reported that the optimum value of C/N ratio ranging in between 26-31 for better composting process.

6. Aeration

During aerobic decomposition, composting process is greatly affected by the amount of oxygen present in composting mass. If the quantity of air is too low, anaerobic decomposition stage may develop, while if the quantity is too high, then it dries the refuse causing loss of heat. Therefore optimum quantity of air should be maintained in composting process.

7. Addition of sewage and sewage sludge.

Sometime sewage or sewage sludge is added in the composting mass in order to maintain C/N ratio of mixture at optimum level. The addition of sewage or sewage sludge also affects composting process.