Abstract

This research was aimed at comparatively revealing the effect of co-digestion in biogas production. Co-digestion is anaerobic digestion of several organic substrates simultaneously. Four locally fabricated digesters were used for cow, pig, poultry and mixed substrate respectively. Batch culture method was used for 21 days. Wheelbarrow tube was used as gas collector, which weighed 420g initially. The set-up was monitored by weighing the tubes daily with digital weighing balance. Gas production started in day 1 and stopped at day 21. The weight of the tubes were measured to be 420g. After setting up the digester, the process was recorded as day zero (0). Production of gas was observed by the increase in the size of the tubes. The indigenous bacteria started working on the substrate Poultry gas the highest gas yield as a single substrate. On the comparative level, the mixed substrate showed a very significant gas production. Gas analysis using gas chromatography revealed that the mixed substrate digestion gave the highest methane production of 87.28 %. Co-digestion has proved to be a better approach in biogas production process. It has the following positive effects, higher gas yield, balanced C:N ratio Improved microbial activity, greater process stability, increase methane content, reduced toxicity and better waste management. The research concludes that co-digestion of good organic substrate is a good approach in biogas production to enhance gas yield.

Keywords

biogas, co-digestion, digester, substrate, dungs, chromatgraphy