Improvement of biogas production from oil palm empty fruit bunches (OPEFB)

Oil palm empty fruit bunches (OPEFB), a waste lignocellulosic material, which is the main byproduct of vegetable oil production industries in Indonesia and Malaysia, was utilized as a source for biogas production. Pretreatments using NaOH as well as phosphoric acid were investigated to improve the biogas production. Clear positive effects of the pretreatments on the yield of methane were observed. The best improvement was achieved when 8% NaOH for 60 min was used for the pretreatment, which resulted in 100% improvement in the yield of methane production. In addition, treatment with phosphoric acid resulted in 40% improvement in the methane yield compared with that of the untreated material. The results showed that the carbohydrate content of OPEFB could be efficiently converted to methane under the anaerobic digestion process. 97% of the theoretical value of methane production was achieved after the pretreatment with NaOH for 60 min. Moreover, the initial rate of methane production was also increased by more than 85% after the treatment with NaOH compared with that of the untreated OPEFB.

► NaOH and H3PO4 pretreatments were used to improve the biogas production from OPEFB. ► Clear positive effects of the pretreatments on the yield of methane were observed. ► The best result achieved was 0.404 Nm3 CH4/kg VS, i.e., 97% of the theoretical yield. ► Modification of the structure and reduction in crystallinity were the main reasons.