Non-isothermal kinetic analysis of sewage sludge from wastewater treatment plant

The thermal decomposition kinetics of sewage sludge was investigated by means of non-isothermal TG at different heating rates of 5 K·min −1 , 10 K·min −1 , 15 K·min −1 , 20 K·min −1 and 30 K·min −1 . The non-isothermal kinetic parameters and mechanical functions were analyzed by means of Flynn-Wall-Ozawa equation and Coats-Redfern equation. Before and after DTG peak, Flynn-Wall-Ozawa and Coats-Redfern were used to determine the kinetic parameters. Before and after DTG peak, E α→0 =102.17 kJ·mol −1 , 88.17 kJ·mol −1 respectively. Before DTG peak, the most probable kinetic function was No.3 G-B Equation, and the corresponding mechanism was controlled by Three-Dimensional Diffusion (cylindrical symmetry). The apparent activation energy and the pre-exponential constant (A) were E β→0 =107.44KJ·mol −1 , lnA β→0 =12.64 respectively. After DTG peak, the most probable kinetic function was No.13 Avrami-Erofeev Equation (n=4), and the corresponding mechanism was controlled by random nuclear producing and growing process. The apparent activation energy and the pre-exponential constant (A) were E β→0 =88.34 KJ·mol −1 , lnA β→0 =14.25 respectively.