Abstract
Food manufacturing waste sludge was treated with heat, acid and base. After the pretreatment, the sludge was digested by the mesophilic digestion process. Digestibility and volume reduction of the sludge were promoted remarkably. The most appropriate pretreatment condition for the maintenance cost was thermal pretreatment at 140°C 60 minutes. Under the thermophilic digestion of foregoing pretreated sludge at 5% MLSS, the gas production was 500 ml/g-vs This gas production was 3 times more than that under the conventional digestion. The increase of digestibility may be attributed to, (1) the solubilization of SS and the thermal denaturation of substrate under the heat treatment process, (2) the elongation of sludge retention time by concentration and (3) high reaction rate and bearing ability to high load under the thermophilic digestion.
