Improved Methane Production Using Lignocellulolytic Enzymes from Trichoderma koningiopsis TM3 Through Co-digestion of Palm Oil Mill Effluent and Oil Palm Trunk Residues

The efficacy of concentrated enzymes from Trichoderma koningiopsis TM3 in hydrolyzing palm oil mill effluent (POME) and oil palm trunk residues (OPTr) at 40 and 50 °C was evaluated prior to methane fermentation. POME hydrolysate containing total sugar concentration of 15.40 g L−1 was obtained from enzymatic hydrolysis using 15 Unit g−1 TVS at 50 °C for 18 h incubation with the hydrolysis yield of 0.35 g total sugars g−1 TVS. The OPTr hydrolysate contained slightly higher total sugar concentration (18.90 g L−1) with the hydrolysis yield of 0.85 g total sugars g−1 TVS under the same condition. Methane production from POME hydrolysate was 6.29% higher than the raw POME. Co-digestion of POME hydrolysate with OPTr gave the maximum methane yield (369 ml CH4 g−1 VS-added) with the increase of 9.28% compared to the raw POME. The methane production rate (Rmax) and the hydrolysis rate constant (kh) of the co-digestion of POME hydrolysate with OPTr were 1.2-fold higher than those of the POME hydrolysate. PCR-DGGE analysis revealed that Clostridium sp. and Petrimonas sp. were dominated bacteria while Methanosarcina sp. and Methanospirillum sp. played an important role in methane production. These results indicated that enzymatic pretreatment and co-digestion of POME hydrolysate with OPTr could improve methane yield from anaerobic fermentation of POME.