Thermal characteristics, kinetics, gas emissions and thermodynamic simulations of (co-)combustions of textile dyeing sludge and waste tea

Abstract The thermal conversion of waste into energy is increasingly becoming an integral part of environmentally friendly and sustainable societies. In this study, the (co-)combustion behaviors, kinetics, and gas emissions of textile dyeing sludge (TDS) and waste tea (WT) were quantified. The addition of WT appeared to avoid the drawbacks of both TDS and WT and to enhance their combustion efficiency. The main co-combustion process was characterized by three stages. The WT addition led to higher reactivity and a better combustion performance. The average apparent activation energy reached its minimum (154.82 kJ/mol) with 40% WT. The reaction mechanisms of the three stages of the 40% WT blend were best described using the D2, F3 and F2.3 models, respectively. The interaction between TDS and WT occurred between 370 and 550 °C. The WT addition changed the peak strength of Fe2O3 and produced NaAlSiO4 and CaSO4. The blend ash composition was found to consist of Fe2O3, CaSO4, Na2SO4, Ca5HP3O13, and NaAlSiO4 according to X-ray diffraction analysis and thermodynamic simulations. The WT addition reduced SO2 emission from the co-combustion. Our results can be benefited to provide pollution reduction, energy generation, performance improvement, scaling-up, and optimization for the industrial applications.