ANAEROBIC DIGESTION OF HIGH SOLIDS-CONTAINING WASTES: ESTIMATION OF KINETICS

The objective of this study was to employ a simple batch test to determine the kinetics of anaerobic digestion of a high solids-containing industrial waste. The industrial waste studied was characterized by total and volatile solids content of 84% and 57%, respectively. Anaerobic digestion of the waste alone and its co-digestion with the waste activated sludge (WAS) were both investigated. Anaerobic digestion kinetics was determined from the CH4 generation rate under various initial substrate concentrations. The calculated substrate utilization rates were then modeled according to the Monod kinetics. The solution to nonlinear regression resulted in the maximum specific substrate utilization rates (k) of 0.138 and 0.165 g COD g VSS−1.day−1 for the waste alone and the waste co-digested with the WAS, respectively. It is concluded that the anaerobic co-digestion of this industrial waste with the WAS is beneficial from the digestion kinetics point of view since the k increased approximately 20% with the addition of the WAS. In addition, kinetics of anaerobic digestion of high solids-containing wastes can be estimated by a simple batch test that is based on monitoring the CH4 generation.