Biogas Production from Cassava Waste Cake in a Two-Stage Anaerobic Digestion System

This research is to produce biogas by using cassava waste cake as a feed stock in a two-stage anaerobic digestion system. The system was designed and built as a pilot-scale plant consisting of mixing tank, a fermented acid tank, two methanogenic tanks and a storage tank connecting in series. Feed stocks were mixed in the mixing tank and then fed into the fermented acid tank. The feeding was a batch feeding with a hydraulic retention time of 12 days. The system was operated to determine the biogas production rate and the net energy production. The temperature of the fermented tanks were set at 35 degrees C during the testing period. The pH value was initially set at 8. The organic loading rate was at 0.417 g COD/ L-day. The results showed that the system can produce biogas at a rate of 140 L/day in average. The net energy production was found to be 48.52 W-h/day.