The effect of inoculum sources on the anaerobic digestion of paragrass was investigated. Two types of
sludge were used as the inoculums: an anaerobic sludge obtained from a domestic wastewater treatment
plant (OS) and a sludge acclimated to fibrous substrates in raw palm oil mill effluent (AMC). Microbial
activity assays showed that the AMC had hydrolytic and acetogenic activities two times greater than
the activities of the OS. In addition, the production of methane from acetate by the AMC occurred without
a lag phase, while it took 8 days for the OS to start producing methane from the same substrate. The biochemical
methane potential after 80 days digestion was 316 ml STP/g VSadded using the AMC, and 277 ml STP/g VSadded using the OS. The methane potential of the paragrass was estimated to be 3337 Nm3 CH4/ha a.