ABSTRACT Palm oil mill effluent (POME) contains high COD levels ranging from 38,080 to 44,928 mg/L. The appropriate method for treating wastewater with high COD concentrations is anaerobic treatment, one of which is using an upflow anaerobic sludge blanket (UASB) reactor. This reactor is effective in wastewater treatment and capable of producing biogas. This study aims to investigate the effec…