Feasibility of Anaerobic Co-Digestion of Waste Activated Sludge Under Thermophilic Conditions

The feasibility of anaerobic co-digestion of waste activated sludge (WAS) with waste wine distillery (WWD) was studied in lab-scale reactor experiments at 55degC. The WAS began with a low biogas production rate of 0.38 1.g^-1VS_added. after mixing with WWD, increased to 0.64 1.g^-1VS_added. In addition, co-digestion of WAS with WWD improved the effluent dewaterability, and, except for zinc, the heavy metal content of the effluent did not exceed the control standard. Meanwhile, an energy balance calculation for co-digestion showed a net energy of +19.96 kJ.d^-1 compared to that of -33.73 kJ.d^-1 for digestion of WAS alone. Moreover, WWD used as co-substrate has the advantages of relatively fixed resources and composition. Co-digestion of WAS with WWD is considered a feasible, economically viable, and ecologically acceptable solution for the safe disposal of WAS. In terms of application in practice, we recommend a 1:3 mixture (WAS:WWD) for co-digestion under thermophilic conditions.