A Brief Overview on the Utilization of Biomass Ash in Biogas Production and Purification

As thermochemical processes of converting biomass to energy have been increasing worldwide, finding economic and environmentally sound solutions to manage and valorize the huge amounts of ash produced is of most importance. To date, several applications have been proposed for biomass ash recycling, among which the biogas industry appears to offer many potential benefits in the context of a circular economy. This works aims to review the studies that have been conducted so far on the use of biomass ash in the processes of biogas production and purification while providing a summary of the historical background of biogas technology, main mechanisms involved in biogas generation, and information about biomass ash characteristics. It is also outlined the major obstacles to the industrial-scale application of biomass ash in biogas technology and discussed possible ways to tackle those barriers. Graphic Abstract