Enhanced biogas production by mesophilic and thermophilic anaerobic co-digestion of palm oil mill effluent with empty fruit bunches in expanded granular sludge bed reactor

This study aimed to utilize Palm Oil Mill Effluent (POME) and preheated Empty Fruit Bunches (EFB) as a source for enhanced biogas production in Expanded Granular Sludge Bed (EGSB) Reactor. The reactor was operated continuously for 48 days with 2 days hydraulic retention time (HRT), POME: EFB mixing ratios of 1: 0; 0.10; 0.15; 0.20; temperature of 35 ± 2±C and 55 ± 2±C. The best improved was achieved from co-digestion of POME with EFB at a mesophilic temperature of 35 ± 2±C and mixing ratios of 1: 0.10, highest total biogas volume achieved was 7,400 ml (0.1359 – 0.1619 m³ CH₄/kg COD removed), Volatile Fatty Acid (VFA)/Total Alkalinity (TA) ratios 0.1418 – 0.1582, and COD removal 61.97 – 78.87 %. The Methane content was 46.10 %. Under a Thermophilic temperature of 55 ± 2±C and mixing ratios of 1: 0, 10, the highest total biogas volume achieved was 1.350 ml (0.0859 – 0.1358 m³ CH₄/kg COD removed) VFA/TA ratios increased to 0.4498 – 0.6685 with COD removal 61.97 – 74.65 %.