Spent Mushroom Substrate Performance for Pyrolysis, Steam Co-Gasification, and Ash Melting

Abstract

Spent mushroom substrate is expected to be utilised as gasification feedstock in the future. This study investigated its performance in pyrolysis, steam co-gasification, and ash melting. Pyrolysis was performed by thermogravimetry-differential thermal analysis, and it was found that higher shoulder curves indicated higher hemicellulose content than timber waste. Steam co-gasification was evaluated using a laboratory-scaled fixed-bed downdraft gasifier. The results showed that blending the substrate with Erianthus enhanced carbon conversion to gas and hydrogen concentration (by 7.5–8.8 points) at a blend rate of 50 wt%, with lower H2S yield due to the formation of CaSO4 on the biomass surface. Furthermore, blending the substrate with Japanese cedar resulted in increased softening and fusion temperatures that can be explained by assuming the formation of calcium minerals (e.g., gehlenite and albite–calcian). Based on these results, spent mushroom substrate demonstrates high potential to serve as regional feedstock by co-gasification.