processes Review Waste to Energy: A Focus on the Impact of Substrate Type in Biogas Production Nwabunwanne Nwokolo 1,*, Patrick Mukumba 1, KeChrist Obileke 1 and Matthew Enebe 2 1 Department of Physics, University of Fort Hare, P/Bag X1314, Alice 5700, South Africa;
[email protected] (P.M.);
[email protected] (K.O.) 2 Department of Microbiology, North-West University, P/Bag X2046, Mmabatho 2735, South Africa;
[email protected] * Correspondence:
[email protected]; Tel.: +27-833433195 Received: 11 July 2020; Accepted: 3 September 2020; Published: 1 October 2020 Abstract: Anaerobic digestion is an efficient technology for a sustainable conversion of various organic wastes such as animal manure, municipal solid waste, agricultural residues and industrial waste into biogas. This technology offers a unique set of benefits, some of which include a good waste management technique, enhancement in the ecology of rural areas, improvement in health through a decrease of pathogens and optimization of the energy consumption of communities. The biogas produced through anaerobic digestion varies in composition, but it consists mainly of carbon dioxide methane together with a low quantity of trace gases. The variation in biogas composition are dependent on some factors namely the substrate type being digested, pH, operating temperature, organic loading rate, hydraulic retention time and digester design. However, the type of substrate used is of greater interest due to the direct dependency of microorganism activities on the nutritional composition of the substrate. Therefore, the aim of this review study is to provide a detailed analysis of the various types of organic wastes that have been used as a substrate for the sustainable production of biogas.