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

Energy recovery from a crossflow ultrafiltration (UF) membrane unit employe d in order to improve the performance of an anaerobic contact digester for the treatment of brewery wastewater was assessed. The performance of the pi lot-scale anaerobic UF membrane system was studied for over 15 months. At s teady-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 eff iciencies of 99% and almost 100% were achieved, respectively. Percent metha ne in biogas was found to be in a range of 67-79% with the corresponding me thane yield of 0.28-0.35 m(3) CH4 kg(-1) CODremoved. The potential energy r ecovery from the system treating brewery wastewater at an OLR of 28.5 kg CO D m(-3) d(-1) was 87 MJ d(-1) which would enable to maintain all energy req uirements of the feed pump, mixing and heating of the reactor contents. In addition to this, 71% of the energy requirement for recirculating the react or content through the membranes would also be recovered.