Optimization of biomethane production by anaerobic digestion of palm oil mill effluent using response surface methodology

This study investigated the effects of factors namely temperature, palm oil mill effluent (POME) volume, inoculum volume, and co-substrate addition such as oil palm empty fruit bunch (EFB) and palm kernel on the anaerobic digestion process for biogas and methane production. Response surface methodology by the Box-Behnken design verified that the specific biogas production rate and methane yield were mainly affected by operating temperature and co-substrate addition. The optimal conditions for the maximum specific biogas production rate (0.0574 m3/ kg chemical oxygen demand per day) and methane yield (25.6%) have been predicted by multiple response optimization and verified experimentally at 47.8 degrees C operating temperature, 50.4 mL POME volume, and 5.7 g EFB addition. The error percentage between experimental and predicted values which were around 5% for methane composition and 12% for specific biogas production rate suggests the good predictability of the model. (C) 2011 Curtin University of Technology and John Wiley & Sons, Ltd.