Decentralized anaerobic digestion systems for increased utilization of biogas from municipal solid waste

Biogas may be able to compete favorably with cheaper fossil fuels for domestic purposes if anaerobic digestion systems are used for processing the organic fraction of municipal solid waste (OFMSW) in a decentralized manner and within an integrated solid waste management scheme. To harness this opportunity, this study reviews how a typical integrated solid waste management system (ISWM) may be reconfigured into one with lower operation costs and minimal GHG emissions. First, four literatures which conducted various environmental analyses on several ISWM scenarios for municipal solid waste management were reviewed to determine which ISWM among them had the lowest quantity of greenhouse gas (GHG) emissions in CO2eq. Then, a simplified comparative economic analysis was conducted on the operation strategies of five different commercial solid-state anaerobic digestion (SS-AD) technologies. This economic analysis was then followed with frugal recommendations on how best an SS-AD system can be incorporated into the 'least GHG emitting' ISWM to lower the operational costs of the ISWM system. The final ISWM superstructure recommended by this study included a centralized section for commercial MSW waste, and a decentralized section primarily for residential MSW waste, and the superstructure was recommended for densely poulated urban areas. Furthermore, the decentralized section of the ISWM superstructure included the collection of source-sorted waste from households, decentralized storage for collected recyclables and digestate, and the sale of biogas exclusively as domestic cooking gas. Innovative design and operational modifications proposed for the decentralized SS-AD system were: modular and detachable digester cells for managing digester bed failure, and a vertical stacking design for achieving compactness and scalability for the digester.