Mushroom cultivation and biogas production: A sustainable reuse of organic resources

The industry of mushroom cultivation uses a wide variety of lignocellulosic waste and is considered a very efficient way to recycle agro-residues and to produce food. This activity generates tons of spent mushroom substrate (SMS) every year, causing a significant disposal challenge. The SMS is a useful resource for the generation of biogas, since raw material is digested by the metabolism of fungi, performing as a pre-treatment, thus facilitating the subsequent anaerobic digestion and increasing the yield of methane production. Forty-one species of fungi have been used as pre-treatment in different types of residues; among them, 13 were cultivated mushrooms. The potential production of methane using SMS pre-treated with cultivated mushrooms should be added to the list of other common residues used, such as food/vegetable waste and pig manure. Biogas can be used as fuel, and the residues from biogas can be used as fertilizers for food crops. These productive activities can be integrated in a virtuous circle of reuse of organic resources; in which the waste of one activity is used as a substrate for another activity. Given the huge amount of SMS produced, we propose to integrate it into a virtuous circle of resource reutilization for energy generation, particularly as a viable substrate for biogas generation.