Thermogravimetric analysis coupled with mass spectrometry of spent mushroom substrate and its fractions

This study aimed at determination of the char, tar and gas production yield during pyrolysis of the spent mushroom substrate left after cultivation, as well as its individual components, namely the casing layer and the mushroom substrate. The pyrolysis process was carried out in a thermobalance combined with a mass spectrometer. Based on the analysis of mass losses, it was found that the largest amount of flammable gases and tar were released during pyrolysis of the spent mushroom substrate. The yield of char, tar and gas during pyrolysis at 600 °C were respectively equal to 57.1, 14.4 and 14.5 wt.%. The loss of mass at temperature above 600 °C was associated with thermal decomposition of calcium carbonate, calcium sulfate, and oxidation of the char. The deconvolution of DTG curves and volatile products such as H2, CH4, CO, CO2, H2O and tar allowed to determine the decomposition of the compounds contained in the spent mushroom substrate during the pyrolysis process. The kinetic parameters were calculated from the isoconversional model for thermal degradation of biomass. The results could aid in managing organic wastes including the energy production.