Effect of the solid content on biogas production from Jatropha curcas seed cake

Anaerobic conversion of Jatropha curcas seed cake was studied in a five-litre working volume batch reactor at 30 degrees C. Over a 60-day operating period, a slurry of seed cake in water at a 1 : 20 seed cake-to-water ratio showed the highest methane yield of 296 litre methane/kg Chemical Oxygen Demand (COD) degraded (or 156 litre/kg of Jatropha curcas seed cake added) and achieved 52% COD removal. The results revealed that Jatropha curcas seed cake treated anaerobically can be a good source of methane, with optimal seed cake-to-water ratio in the range of 1 : 20 to 1 : 10.