Effect of Co-Digestion on biogas Production-A case study of Cow Slurry with Maize Cob

Attempt was made to investigate the effect of co-digestion on biogas production using cow slurry and maize cob. Cow slurry and maize cobs were co-digested at ratios 3:1, 1:1 and 1:3 respectively using the percentage volatile solid of each substrate. The investigation was carried out in a laboratory scale (batch experiment). The digester was fed with the calculated amount of cow slurry-maize cob mixtures. Co-digestion of cow slurry with maize cobs at the selected ratios has biogas yields of 0.453, 0.417 and 0.429m3/kgoDM respectively while the methane yields were 0.334, 0.323 and 0.323m3CH4/kgoDM respectively at mesophilic temperature (37oC). From the fresh mass of the substrate, biogas yields of 0.053, 0.065 and 0.100 m3/kgFM were obtained at mesophilic temperatures for cow slurry-maize cob ratios of 3:1, 1:1 and 1:3 respectively while the methane yields from the fresh mass for the same ratios were 0.039, 0.050 and 0.076 CH4/kgFM respectively. Co-digestion of cow slurry with maize stalk was found to have methane concentrations of more than 70% in each case. In all, it can be concluded that co-digestion of cow slurry with maize cob has a notable positive effect on biogas production.