Thermophilic solid-state anaerobic digestion of solid waste residues from palm oil mill industry for biogas production

Abstract

Thermophilic solid-state anaerobic digestion (SS-AD) of biomass from palm oil mill industry, including empty fruit bunches (EFB), oil palm fronds (OPF) and oil palm trunks (OPT) were investigated under different feedstock-to-inoculum ratios (F:I), carbon-to-nitrogen ratios (C:N) and total solids contents (TS). The optimal condition for biogas production was achieved at F:I ratio of 2:1, C:N ratio of 40:1 and TS content of 16%. The highest methane yield from EFB, OPF and OPT were 223, 207 and 161m3 CH4 tonne−1 VS, respectively. Bacterial community structure in thermophilic SS-AD of oil palm biomass was dominated by Thermoanaerobacterium sp. and Clostridium sp. Archaeal community structure was dominated by Methanosaeta sp. and Methanoculleus sp. The highest methane production of 45m3 CH4 tonne−1 fresh biomass was achieved from EFB. Solid waste residues from palm oil mill industry have great potential for methane production via thermophilic SS-AD.