Sewage and textile sludge thermal degradation kinetic study using multistep approach

This study performed TGA coupled with FTIR to evaluate the evolved gas and kinetic parameters of sewage and textile sludge thermal decomposition. Temperature-based FTIR spectrum presented common organics and also some nitrogen and sulfur-containing compounds in the produced gas. A multi-step determination of the kinetic analysis with TGA data could provide a more reasonable interpretation of kinetic triplets, including the activation energy and reaction mechanism. Hence, using the multi-step method would avoid overestimation for further calculation. The multi-step-based method yielded kinetic parameters for three pseudo reactions during the decomposition of sewage sludge (SS), textile sludge (TS), and their blends. Compared to sewage sludge, the activation energy of textile sludge for three consecutive stages varied more widely in the 90–160, 100–190, and 230−320 kJ/mol range, respectively. Aside from the activation energy, the reaction mechanism and pre-exponential factor would enrich sludge decomposition kinetic insight.