A Non-isothermal Thermogravimetric Kinetic Analysis of Malaysian Sewage Sludge

Dewatered sewage sludge is one of the largest contributors of waste material in Malaysia and it indirectly elevates local environmental problems. Previous studies have indicated sewage sludge as a potential alternative fuel based on its higher heating values. To explore sewage sludge as an alternative solid fuel will not only address energy demand issues, it will also mitigate long term disposal problems related with the waste material. Further information on combustion characteristics of this material is required before any links to power generation applications can be established. In this work the combustion characteristics of Malaysian sewage sludge was studied by means of thermogravimetric analysis (TGA) under different heating rates (10, 20 30 and 40 K/min). Non-isothermal thermogravimetric data were used to assess the kinetics of the combustion of sewage sludge by the application of Ozawa-Flynn- Wall and Vyazovkin kinetic models. The average activation energies were found to be 82 and 79 kJ/mol respectively. The average reaction order corresponding to sewage sludge combustion was 0.11.