Thermogravimetric analysis of the co-combustion of paper mill sludge and municipal solid waste

Highlights: • Thermogravimetric analysis of paper mill sludge and municipal solid waste were studied. • The combustion of paper mill sludge could be improved by blending municipal solid waste. • There existed significant interaction during co-combustion of the blends. • The OFW and Starink methods were used to obtain the activation energy. • The average activation energy was the lowest by blending 20% municipal solid waste. - Abstract: The thermal characteristics and kinetics of paper mill sludge (PMS), municipal solid waste (MSW) and their blends in the combustion process were investigated in this study. The mass percentages of PMS in the blends were 10%, 30%, 50%, 70% and 90%, respectively. The experiments were carried out at different heating rates (10 °C/min, 20 °C/min and 30 °C/min) and the temperature ranged from room temperature to 1000 °C in a thermogravimetric simultaneous thermal analyzer. The results suggested that the ignition temperature and burnout temperature of MSW were lower than that of PMS, and the mass loss rate of MSW was larger especially at low temperatures. There were only two mass loss peaks in the differential thermogravimetry (DTG) curve, while three mass loss peaks were observed when the blending ratios of PMS were 30%, 50%, 70%. The value of the comprehensive combustion characteristic index of the blends indicated a good combustibility when the percentage of PMS (PPMS) in the blends was less than 30%. There existed certain interaction between the combustion process of PMS and MSW, especially at high temperature stage. Activation energy (E) value obtained by the Ozawa–Flynn–Wall (OFW) method and the Starink method were very consistent. When the mass percentage of PMS in the blends was 80%, the E average value attained the minimum