BIOMETHANATION POTENTIAL OF ANIMAL FLESHING AND PRIMARY SLUDGE AND EFFECT OF REFRACTORY FRACTION OF VOLATILE SOLIDS

Batch studies on anaerobic digestion were performed in 100ml bench top digesters (serum bottles) with solid wastes (limed fleshing) generated from tannery and primary sludge from effluent treatment plant of tannery liquid waste. Digestion was carried out under mesophilic condition. Batch reactors were run at two different organic loading rates. Gas production was higher in test reactor 1 (volatile solids load of 51.9 g/l) than test reactor 2 (volatile solids load of 15.8 g/l). VFA concentration in test reactors 1 and 2 had reduced by 11,970 mg/l (43%) and 2115 mg/l (28.4%) respectively. As biodegradability fraction present in the tannery solid wastes was lower, lag time for the onset of maximum gas production was longer. Based on experimental observation it is concluded that it is more appropriate to evaluate biomethanation potential of solid wastes in terms of biodegradable fraction of volatile solids present in the wastes.