Abstract:
Biogas is eco-friendly alternative renewable energy source produced through anaerobic digestion of organic compounds. In this study, biogas production was evaluated from Cucurbita pepo leaves (CP) and cow dung (CD) co-digestion in five mix ratios under mesophilic conditions (38ºC) using batch digesters in the Botany Laboratory of Haramaya University. Total solid(TS) and Volatile solid(VS), organic carbon, and pH were measured before and after digestion, While carbon to nitrogen ratio was measured only before anaerobic digestion (AD). The daily biogas production was subsequently measured by water displacement method for 30 days. Results show that all measured physico-chemical parameters of each substrate were significantly varied between before and after AD. After AD degradation of organic carbon was highest (17.06%C) for 75% CD and 25% CP. After anaerobic digestion, % TS and % VS of all treatments were significantly lower than those of the before AD. Biogas production was detected in both substrate and substrate mix ratios from the first day of digestion and declined to zero in about 29 days of incubation. The maximum (1051ml) cumulative biogas was measured in 75% CD and 25% CP while the minimum (609ml) was measured in100% CD. Assessment of cumulative biogas production revealed that the substrate mix ratio of 75% cow dung and 25% Cucurbita pepo was superior to others (1051ml),suggesting this mix ratio of the two substrates is an optimal mix ratio to yield better amount of biogas. Therefore, use of both substrates in combination is better than using them alone for biogas production.
