Valorization of Spent Mushroom Compost Through a Cascading Use Aproach

Spent mushroom compost (SMC) is a waste byproduct generated by the mushroom industry, with the current disposal methods involving landfills or incineration, causing environmental problems. This study introduces a cascading valorization based on circular economy. A water-washing pretreatment is suggested to reduce the ash content and improve the calorific value. Furthermore, an oxidative torrefaction is proposed to enhance the physicochemical properties and evaluate the residence time, temperature, and initial weight effects. The investigation revealed that the calorific value increased by 49.46% in the best water washing scenario and the SMC contains laccase. During SMC torrefaction, mass and energy yields exceeded 80%, and the calorific value was improved. Finally, torrefaction in situ CO2 capture was achieved by forming CaCO3, with a mass fraction increase of up to 7.4%. The study describes the cascading innovation use of this residue on a TRL4 higher than previously reported studies, thereby contributing to gaining an understanding of sustainable industrial mushroom production.