BIOGAS PRODUCTION FROM WHEAT STRAW CO-DIGESTED WITH POULTRY AND GOAT MANURE

Abstract

Biogas production using anaerobic digestion of organic waste materials provides an alternative environmentally friendly renewable energy. In this study, the production of biogas from co-digestion of wheat straw with poultry and goat manure was evaluated in seven treatment under mesophilic condition 380C for30 days of retention time, using a batch digester in Botanical and Central Laboratories of Haramaya University. Total solids, volatile solids, percent moisture content, pH, organic carbon, organic nitrogen and carbon to nitrogen ratio were measured following standard methods for all substrates before and after digestion. The results indicates all measured physicochemical parameters of each substrate was significantly (P<0.005) different between before and after anaerobic digestion. The maximum yield of biogas production was observed on T5 at a temperature of 800C as compared to the temperature of 60 0C. However, the least biogas production was recorded on treatment T9 with a temperature of 800C when compared to all treatments. Production of biogas was observed in all treatment from day three of anaerobic digestion. The production of biogas rise very rapidly after 4thday to 17th day of anaerobic digestion and start to decline to zero at about 30 days in all substrates. Assessment of cumulative biogas production revealed that the substrate mix ratio of 50% WS and 50% PM showed the highest biogas production, suggesting the potential of adding equal amount of wheat straw and poultry manure to significantly improve biogas production.