Valorization of biomass ash in biogas technology: Opportunities and challenges

Despite the increasing global focus on replacing fossil fuels with biomass resources, handling the enormous quantity of ash from biomass thermochemical conversion processes into energy remains a serious challenge from both environmental and economic points of view. Therefore, in pursuit of the circular economy, the use of biomass-derived ash in beneficial applications can have a great contribution to address problems related to ash disposal, and at the same time to promote the valorization of wastes. This work attempts to provide a clear insight into the feasibility of the utilization of biomass ash in a valuable field, namely anaerobic digestion and biogas technology, along with a brief statement of possible opportunities and challenges.