BIOGAS PRODUCTION FROM NIGHT SOIL - EFFECTS OF LOADING AND TEMPERATURE

Anaerobic digestion of night soil was carried out in 25-litre digeters at 20-degrees-C. Digesters with 20-25 days HRT produced 23-28 litre biogas day-1 with 60-63% methane content. The volatile fatty acids and pH were maintained below 800 ppm and around 7.3, respectively. Batch studies at 5-30-degrees-C showed increased biogas production with temperature, and with volatile solids up to 6.2%. Volatile fatty acids, in general, increased directly with volatile solids and inversely with temperature. Microbial counts and enzyme activities in the stabilized digesters are also reported.