Kinetic study of the pyrolysis of sewage sludge

Pyrolysis of sewage sludges has been studied by means of thermogravimetric analysis. Different possible kinetic models of thermal decomposition have been considered using different heating rates. Two types of sludges, non-digested and anaerobically digested, have been pyrolysed. The best model considers three different organic fractions in sludges, each of them associated with a different thermal behaviour. This model shows an increase in the relative amount of the fraction that is decomposed at the highest temperature as a consequence of the process of digestion. (C) 1997 ISWA.