Effect of Temperature on the Performance of an Up-flow Anaerobic Sludge Fixed Film (UASFF) Bioreactor Treating Palm Oil Mill Effluent (POME)

This study investigates the performance of anaerobic digestion of palm oil mill effluent (POME) in an up-flow anaerobic sludge fixed film (UASFF) bioreactor at four different temperatures (24, 38, 50 and 60 °C) under optimized operating conditions (feed flow rate (QF) of 1.5 L day and up-flow velocity (Vup) of 0.75 m/h). Influent COD concentration was 14150 mg/L. Six quality parameters viz. COD removal, methane yield, TSS removal, oil and grease removal, effluent volatile fatty acids (VFA) and pH were monitored as the process response. COD removal and methane yield of 92% and 0.325 CH4/g CODremoved day were achieved respectively in mesophilic temperature (38 °C) at HRT of 1.5 day. Higher values (94% COD removal and 0.331 CH4/g CODremoved day) were obtained under thermophilic condition (50 °C). A 94% oil and grease removal was achieved at a temperature of 50 °C while it was 85 and 65% at 38 and 24 °C, respectively. The granules structure and activity did not undergo any changes at temperature of 50 °C. An increase in temperature from 50 to 60 °C caused a detrimental effect on treatment efficiency as the methanogenic activity was relatively terminated within <6 days.