Comparative Study on the Rates of Production of Biogas from Organic Substrates

Abstract

Interest in renewable energy production and in reduction of the greenhouse gas emissions associated with fossil fuels has made anaerobic digestion of organic wastes an attractive option for alternate means of producing biogas (methane). In this present work, investigation was carried out on the unused energy present in cooked left-over waste rice as food waste and the amount of methane produced compared to cow dung and co-substrate used as feed stocks. The experiments were conducted batch wisely at mesophilic temperature with the varying percentage total solid (TS) and volatile solid (VS) calculated. It was observed that the volume of methane produced increased with increasing percentage total solid and percentage volatile solid during the 20 day HRT digestion period. The optimum quantity of methane gas produced was 57,306 ml at the highest 92.1% VS and 12.1% TS from food waste ( oryza sativa ), followed by the co-substrate 12,190 ml and cow dung 9802 ml. The high nutritional content and calorific value present in kitchen food waste contributed to its overall yield within the shortest time interval which indicates a rapid rise through the exponential phase of microbial growth rate. Furthermore, the results obtained reveal that food waste especially cooked left-over rice should be considered as a viable feed stock for biogas production in an anaerobic digestion process.