Comparative analysis of biogas and yields from cattle, sheep, poultry wastes and their combinations

A comparative analysis of biogas yields from cattle, sheep and poultry wastes as well as that of their blends was carried out at the mesophilic temperature range (30°C – 40°C) in a laboratory scaled conventional digestive system - batch flow micro digesters made of air-impermeable plastic containers with effective volume of about 4 litres. The Experiments was carried out in three replicates at varying total solid concentrations (5%, 15% and 25%) and monitored for 8 days detention period (anaerobically digested) with a one day lag period observed for bacteria activation on the slurries. The biogas yields from these livestock wastes were compared as well as the variation of the total solid (TS) concentration with the biogas yield from the wastes together with their combinations. Seven batch type anaerobic laboratory – scale digesters were used. Biogas measurement was by the water displacement method. Hydrogen ion concentration (pH), ash content of the pulverized materials before and after digestion was determined The result showed that the composite blend of the three livestock (cattle + sheep + poultry) wastes has the highest biogas potential at 15% total solids concentration which peaked during the fourth day. There was a significant difference at 5% confidence level (P ˃ 0.05) between the digestion of carbon before and after digestion and hence increase C:N ratio which favoured complete digestion. There was positive correlation of all the proximate analysis parameters before and after digestion. This shows good prospects for utilizing the blend of these wastes to produce biogas for useful applications in the farms as well as for normal domestic heating purposes.