Abstract
It is widely known that the degradation of waste activated sludge is a slow process with a low extent of degradation. Improvement methods with regards to bio-methane yield were investigated in this study using a laboratory batch anaerobic digester. Mono-digestion of sludge with a C: N ratio of 15.47 resulted in a lower accumulation of gas volume than co-digested sludge even though the pH decreased rapidly in both cases. The thermophillic anaerobic digestion of sludge and co-digested sludge also produced higher bio-methane yield than mesophillic digestion of waste water sludge. Gas accumulation volume in the digesters during thermophillic digestion increased from 50 Nml to 100 Nml, 200 Nml to 600 Nml and 600 Nml to 750 Nml for sludge, cow dung and sludge and sludge and food waste respectively as the temperature was increased from 37o C to 45o C.