This paper aimed at evaluating the effect of thermal treatment of excess anaerobic sludge upon the biodegradability characteristics of the remaining organic fraction, using biogas generated in the wastewater treatment process as energy source. Direct burning of the biogas allowed an increase in the sludge temperature up to values close to 75º C, for a seven-hour heating period. Samples taken at different heating times showed significant increase of the biodegradability characteristics of the thermally treated sludge, with augments of around 60 times for filtered BOD, 30% for total BOD and 50% for biogas production. In addition, no adverse effect on effluent quality was noticed when the thermally treated sludge was returned to the UASB reactor.
biodegradability; biogas; anaerobic sludge; UASB reactor; thermal treatment
