Biogas Production from Biomass Residues of Palm Oil Mill by Solid State Anaerobic Digestion

Solid state anaerobic digestion is a safe and environmental friendly technology to dispose solid wastes, could produce methane and reduce the volume of wastes. Three biomass residues from palm oil mill plant including empty fruit bunches (EFB), palm press fiber (PPF) and decanter cake (DC) were evaluated for methane production by solid state anaerobic digestion. Oil palm biomass was mixed with inoculum at F/I ratio of 2:1, 3:1, 4:1, 5:1 and 6:1 based on the volatile solid (VS). Results show that among the five F/I ratios tested, the F/I ratio of 2:1 gave the highest methane yield and methane production for all biomass residues. The highest cumulative methane production of 2180 mLCH₄ was obtained from EFB followed by PPF (1964 mL CH₄) and DC (1827 mL CH₄) at F:I ratio of 2:1. The highest methane yield of 144 mL CH₄/gVS was obtained from EFB followed by PPB (140 mL CH₄/gVS) and DC (130 mL CH₄/gVS) at F/I ratios of 2:1. Methane production from EFB, PPF and DC by SS-AD was 55, 47 and 41 m ³ CH₄/ton, respectively. These results collectively suggested that EFB could be a promising substrate for methane production by SS-AD.