Following are the factors affecting methane production:
1. Slurry:
Proper solubilisation of organic materials (the ratio between solid and water) should be 1:1 when it is house hold type.
2. Seeding:
In the beginning, seeding of slurry with small amount of sludge of another digester activates methane evolution. Sludge contains acetogenic and methanogenic bacteria.
3. pH:
For the production of sufficient amount of methane, optimum pH of digester should be maintained between pH 6-8 as the acidic medium lowers down methane formation.
4. Temperature:
Fluctuation in temperature reduces methane formation, because of inhibition in growth of methanogens. In case of mesophilic digestion, temperature should be between 30°C and 40°C but in case of thermophilic ones, it should be between 50 and 60°C.
5. Carbon-nitrogen (C: N) ratio:
Improper C: N ratio lowers methane production. Maximum digestion occurs when C: N ratio is 30: 1. Amendment of nitrogen or carbon substrates should be done exogenously according to chemical nature of substrate.
6. Creation of anaerobic conditions:
It is obvious that methane production takes place in strictly anaerobic condition; therefore, the digesters should be totally air tight. In Indian conditions, digesters are burried in soil.
7. Addition of algae:
Ramamoorthy and Sulochna (1989) have found an enhancement in biogas production on addition of algae, Zygogonium species. The amount of biogas produced from the algae was twice (344 ml/g dry algae) in comparison to cow dung (179 ml per g dry cow dung). Therefore, addition of algae holds promise to get biogas in sufficient amount.
