Evaluation of the Feasibility of Biogas Production from Leftover Foods of Bahir Dar University Students’ Cafeteria

The aim of this research is to generate biogas, an alternative and viable source of energy for household consumption in particular, from substrate consisting of leftover foods collected from Bahir Dar University students’ cafeteria and cow dung, taken in a weight ratio of 7:3. The production of biogas from the substrate was attempted using plastic digesters of 150 L, 20 L, and 1.8 L capacity under anaerobic conditions. The leftover foods were collected from the student’s cafeteria while cow dung was fetched from the University’s ranch. The production of biogas was monitored over a period of 60 days. Parameters such as pH, temperature, total solids, volatile solids, and ash and moisture contents of the raw and digested sludges were determined using standard methods. The average volume of biogas produced from three separate digesters, each volume of 1.8 L, was measured using water displacement method and was found to be 5.6 ml of biogas per gram of substrate. Injera with shiro stew, vegetable sauce and injera with peas kik stew have higher %VS/TS suggesting their usefulness as desirable substrates for biogas generation. The flammable gas was observed from laboratory scale digesters, on 45th day after charging the waste. As shown in the result, reduction of total solids and volatile solids of food waste was observed after digested sludge was treated for solid analysis. This indicates that, the raw substrate charged in the digester was degraded to produce biogas. Food waste has a highest organic content and biodegradability, so it is a useful substrate for biogas production.