Comparative assessment of anaerobic digestion of municipal solid waste at mesophilic and thermophilic temperatures

Anaerobic digestion is an environmentally sound treatment option for the organic fraction of municipal solid waste (OFMSW) and simultaneously producing methane gas which is a source of renewable energy. The COD reduction of the substrate was 72% for the mesophilic condition and 72.3% for the thermophilic condition. 1200 cm(3) of methane was produced in the mesophilic condition and 1260 cm(3) in the thermophilic condition. The methane content, by volume, in the biogas was found to be 60% and 63% in the mesophilic and thermophilic condition respectively. It was also found that 0.723 cm(3) of methane per unit weight of substrate was produced at the mesophilic condition and 0.760 cm(3) of methane per unit weight of substrate at the thermophilic condition. The gas production rate for mesophilic and thermophilic condition were 0.0214 m(3) (m(3)d)(-1) and 0.046 m(3) (m(3)d)(-1) respectively and the methane yield was more or less the same in both cases. The methane yield in mesophilic condition was 0.0614 m(3)/kg COD and that at thermophilic condition was 0.0612 m(3)/kg COD.