BIOGAS PRODUCTION FROM CO-DIGESTION OF COW MANURE AND AVOCADO FRUIT PEEL WASTE

Abstract

Energy is one of the most important factors for human development and to global economic growth. Biogas is a mixture of gases, mainly methane and carbon dioxide, resulting from anaerobic digestion of organic matter. In this study, biogas production from co-digestion of cow manure (CM) and avocado fruit peel (AF) waste in five mix ratios (100%CM, 60%CM:40%AF, 50%CM:50%AF, 40%CM:60%AF and 100%AF) were evaluated under mesophilic condition at 38ºC using a batch mode digester in Microbiology Laboratory of Haramaya University. In all the treatments, physico-chemical parameters such as pH, total solid, volatile solid, organic carbon, total nitrogen and carbon to nitrogen ratio were measured all substrates before and after anaerobic digestion. The results showed that all measured physico-chemical parameters of each substrate significantly (P<0.05) varied before and after anaerobic digestion. Gas production was noticed in all of the digesters from first day of anaerobic digestion. The Higher daily mean biogas amount was produced at day 3 and 4 for all substrate and decreased to zero at about 30 days in all substrates. The maximum Cumulative biogas production revealed that substrate in a mix ratio of 40%CM+60%AF (T4) yielded (992.56mL) the highest biogas production, while the minimum (716.39mL) was measured in 100% cow manure (T1). Highest reductions of TS (18.39%) and VS (8%) recorded in T4. Overall, the T4 was the best mix among all other treatments which produced high cumulative biogas production.