Assessment of biogas use as an energy source from anaerobic digestion of brewery wastewater

Energy recovery from a crossflow ultrafiltration (UF) membrane unit employed in order to improve the performance of an anaerobic contact digester for the treatment of brewery wastewater was assessed. The performance of the pilot-scale anaerobic UF membrane system was studied for over 15 months. At steady-state conditions, an organic loading rate of 28.5 kg COD m^-3 d ^-1, a hydraulic retention time of 4.2 days and overall COD and BOD removal efficiencies of 99% and almost 100% were achieved, respectively. Percent methane in biogas was found to be in a range of 67-79% with the corresponding methane yield of 0.28-0.35 m³ CH₄ kg ^-1 COD _removed. The potential energy recovery from the system treating brewery wastewater at an OLR of 28.5 kg COD m^-3 d^-1 was 87 MJ d ^-1 which would enable to maintain all energy requirements of the feed pump, mixing and heating of the reactor contents. In addition to this, 71% of the energy requirement for recirculating the reactor content through the membranes would also be recovered.