NaOH presoaking combined with hydrothermal processing of empty fruit bunch (EFB) as co-substrate in palm oil mill effluent (POME) anaerobic digestion

Anaerobic co-digestion produces biogas from Palm Oil Mill Effluent (POME) and Empty Fruit Bunch (EFB). However, EFB has high lignin content, a limiting substance in the co-digestion process. Two samples were controls, with CTRL1 mono-digesting of POME and CTRL2 co-digesting with untreated EFB. NaOH solution at 0.1% was used to presoak EFB to obtain an alkaline condition. The EFB was then treated hydrothermally in an autoclave at 150 °C, 180 °C and 200 °C (HT150, HT180 and HT200). Next, the pretreated EFB was added to POME and fermented anaerobically under mesophilic conditions (27-30 °C) for 21 days. It was concluded that the delignification of EFB was best achieved at 180 °C with a decrease in lignin of 33.95% and an increase in biogas production of 202.32%, compared to CTRL1.