Evaluation of Aerobic and Anaerobic Co-Digestion of <i>Tetraselmis suecica </i>and Oil Palm Empty Fruit Bunches by Response Surface Methodology

Abstract

This study investigated co-cultivation of Tetraselmis suecica microalgae with Oil Palm empty fruit bunch (OPEFB) for anaerobic biomethane production and Palm oil mill effluent (POME) treatment. The highest specific biogas production (0.1162 m3 kg-1 COD day-1) and biomethane yield (3900.8 mL CH4 L-1 POME day-1) was achieved with microalgae at 2 mL mL-1 POME, and OPEFB at 0.12 g mL-1 POME. Without co-digestion of microalgae, higher specific biogas production (0.1269 m3 kg-1 COD day-1) but lower biomethane yield (3641.8 mL CH4 L-1 POME day-1) were observed. Second order polynomial model fits the data well with less than 5% error. Higher removal efficiency (62-95%) of COD, BOD, TOC and TN were achieved by aerobic and anaerobic treatment of POME with microalgae than without microalgal treatment after 3 and 7 days of hydraulic retention time (HRT).