The efficiency of biogas generation depends upon the following factors:

a) Acid formers and methane fermentors must remain in a state of dynamic equilibrium which can be achieved by proper design of digester.
b) Anaerobic fermentation of raw cow dung can takes place at any temperature between 8 and 55°C. The value of 35°C is taken as optimum. The rate of biogas formation is very slow at 8°C. For anaerobic digestion, temperature variation should not be more than 2 to 3°C. Methane bacteria work best in the temperature range of 35 and 38°C.

c) A pH value between 6.8 and 7.8 must be maintained for best fermentation and normal gas production. The pH above 8.5 should not be used as it is difficult for the bacteria to survive above this pH.
d) A specific ratio of carbon to nitrogen (C/N ration) must be maintained between 25:1 and 30:1 depending upon the raw material used. The ratio of 30:1 is taken as optimum.
e) The water content should be around 90% of the weight of the total contents. Anaerobic fermentation of cow dung proceeds well if the slurry contains 8 to 9% solid organic matter.
f) The slurry should be agitated to improve the gas yield.
g) Loading rate should be optimum. If digester is loaded with too much raw material, acids will accumulate and fermentation will be affected.