Impact of Fermentation Duration on Pyrolysis Kinetic Characteristics of Municipal Solid Waste

This work focuses on the effects of component deterioration on pyrolysis kinetics during the fermentation of municipal solid waste. By simulating the urban solid waste stacking environment, waste paper, PVC powder, kitchen waste, and wood and bamboo chips were mixed in a specific proportion, and fermentation experiments were carried out at a constant temperature of 40 °C for 7 days. After daily sampling, the pyrolysis experiment was carried out using a synchronous thermogravimetric analyzer, and the change law of pyrolysis characteristics was studied by combining kinetic analysis methods. The results indicated that the waste pyrolysis process could be divided into two distinct stages. The average activation energy was 180-200 kJ/mol in stage I (200-380 °C) and 268-360 kJ/mol in stage II (380-550 °C). During the first 3 days of fermentation, the activation energy increased, peaking at 201.22 and 358.79 kJ/mol in stages I and II, respectively. Concurrently, the pyrolysis char yield gradually reached its maximum, and the peak temperature shifted to the lower temperature region. After 4-7 days of fermentation, the activation energy significantly decreased, reaching 179.57 and 268.47 kJ/mol on the seventh day. The pyrolysis char yield also exhibited a decreasing trend. Kinetic analysis using the master plot method demonstrated that both pyrolysis stages followed random nucleation and growth mechanisms. As the fermentation duration increased, the reaction mechanism of stage I transitioned from a two-dimensional to a three-dimensional random nucleation and growth process, while stage II evolved from a three-dimensional random nucleation process to the Avrami-Erofeev model.