The effectiveness of cow dung for biogas production was investigated, using a laboratory scale 10L bioreactor
working in batch and semi-continuous mode at 53oC. Anaerobic digestion seemed feasible with an organic loading of up to
1.7 kg volatile solids (VS)/L d and an HRT of 10 days during the semi-continuous operation. The averaged cumulative
biogas yield and methane content observed was 0.15 L/kg VS added and 47%, respectively. The TS, VS and COD removals
amounted to 49%, 47% and 48.5%, respectively. The results of the VS/TS ratio showed very small variation, which denote
adequate mixing performance. However there was some evidence of ammonia inhibition probably due to the uncontrolled
pH employed. The data obtained establish that cow dung is an effective feedstock for biogas production achieving high
cumulative biogas yield with stable performance. The future work will be carried out to study the effect of varying organic
loading rate on anaerobic digestion of cow dung in a semi-continuous mode.