Kinetics of Co-Pyrolysis of Waste Biomass with Miscanthus giganteus

The main substrate used in the pyrolysis process was Miscanthus giganteus, an energy plant. The second substrates used were municipal sewage sludge, municipal sewage sludge with lime, industrial sewage sludge, and spent mushroom substrate. The waste biomass contained ash ranging from 19 to 42%. In this study, the waste biomass was added to the Miscanthus giganteus in proportions of 0.25, 0.50, and 0.75. The study was carried out in a thermobalance at temperatures ranging from 30 to 600 °C in an inert atmosphere. The heating rate was set at 5, 10, and 20 °C/min. The kinetics of co-pyrolysis were determined using the Flynn–Ozawa–Wall method known as a model-free isoconversional technique. The results of the study indicate that as the conversion degree increases, the activation energy changes, suggesting a multi-step pyrolysis process. Adding waste biomass to Miscanthus giganteus increased the activation energy of the pyrolysis process in all cases. According to the activation energy, the greatest synergistic effect was achieved by adding municipal sewage sludge to Miscanthus giganteus.