Comparative assessment of compositing and anaerobic digestion of municipal biodegradable waste in Harare, Zimbabwe

Composting and anaerobic digestion (AD) of biodegradable waste were assessed for their benefits from literature and environmental impacts using the life cycle impact assessment (LCIA) procedure. Literature review findings indicate an overall edge for AD over composting largely due to its renewable energy production capabilities, reduced exhaust emissions, and cost effectiveness considering the entire municipal solid waste (MSW) life cycle. LCIA results show that both AD and composting lead to increases across the four impact categories considered namely, global warming, human health, eutrophication, and acidification. AD however showed lower contributions than composting to global warming, human health, and acidification. Composting only showed lower contribution than AD with regards to eutrophication. Overall study results indicate an edge for AD over composting in treating and managing biodegradable fraction of MSW generated in Harare and its surrounding urban and peri urban environments of Chitungwiza, Epworth, Norton, and Ruwa.