Recoverable potential of electric energy from biogas produced anaerobic digestion of food waste: the case of Jimma University.

Abstract

Food waste (FW) getting changed into biogas not only becomes an alternative resource of energy but also helps in reducing the methane fabrication which is one of the green house gases that cause global warming. In this research the estimation of FW generation rate is the initial steps work when considering the energy recover through the Anaerobic Digestion (AD) method. The aim of this study is to investigate the recoverable potential of electric energy from FW. FW is obtained from Jimma University student cafeteria and specialized hospital. Two fabricated laboratory-scale digesters were used to digest the FW with different concentration of moisture (H2O) content and also by adding inoculates as a microbial sources and catalyst by using AD technology through batch reactor process systems and mesophilic type temperature conditions Experimental analysis was conducted. The water displacement method was used to investigate the volume of biogas produced and methane gas identification was done through biogas analyzer machine. The total production rate of biogas was found to be 260.18ml/225g of waste within 70% of H2O content in a day, which was produced large biogas whereas it was 188.9 ml/150g with an average production rate in a day with 80% of H2O content and it was less biogas production. In general, the study was estimate FW generation rate from Jimma University which account to 2.036tonns/day and 752.558tonnes/year. Biogas production from FW through an AD of 5L capacity digester in the lab scale was evaluated for 23 days. The total amount of biogas production recorded was about 2463ml (58.16% CH4) in reactor1 and 2266.5ml(55.07%CH4) in reactor 2 which can recover 0.053kwh/day( i.e 19.4kwh/year) and 0.0043kwh/day (i.e. 1.57kwh/year) electrical energy respectively. Based on this we can recover electrical potential energy which accounts to 17677.89kwh/d and 6452428.35kwh/y from752.558tones/y FW. Finally it recommend that large FW generation disposed to land fill can be converted to biogas through mono-AD process as alternative sources of electrical potential energy recoverable which can reduce scarcity of electrical energy supply and LPG costs, which is mandatory to sustainable development of social, economical and environmental feasibility.