Biogas generation from food waste through anaerobic digestion technology with emphasis on enhancing circular economy in Sub-Saharan Africa – A review

Globally, 2.2 billion tons of municipal solid waste (MSW) are generated, primarily being disposed of as landfills and couple with fossil fuels (FFs) in polluting the environment resulting in the loss of over 600,000 human life in Sub-Saharan Africa (SSA). Besides, MSW particularly food waste (FW) is a potential alternative clean energy source and is abundant in urban and rural areas. The impact and challenges of FW on biogas production particularly in Sub-Saharan Africa, are not well understood. Still, there exists a large gap of access to clean energy in SSA compared to the rest of the world, especially G20. Therefore, this review explores the impact and challenges of utilizing FW for retrieving biogas for use as clean energy source in urban and rural areas in SSA towards attainment of sustainable development goal 7 (SDG7) and reduce human loss of life resulting from the use of harmful energy sources. The findings reveal that the impact of energy retrieved from FW alone through anaerobic digestion (AD) process is minimal and faces feedstock, structural and AD technology associated challenges. Anaerobic co-digestion of FW with animal manure and the integration of pyrolysis and AD process can significantly address these challenges. Based on the amount of FW availability, a significant impact of biogas from FW can be as high as 57 % and 43 % in urban and rural areas, respectively, if such challenges are timely addressed. This can greatly reduce human loss of life and increase access to clean energy, promote circular economy, protect the environment, and accelerate achievement of SDG7.