Performance evaluation of a mesophilic (37°C) upflow anaerobic sludge blanket reactor in treating distiller's grains wastewater

The performance of a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor treating distiller's grains wastewater was investigated for 420 days at 37 degrees C. After a successful start-up, 80-97.3% chemical oxygen demand (COD) removal efficiencies were achieved at hydraulic retention times (HRT) of 82-11 h with organic loading rates (OLR) of 5-48.3 kg COD m(-3) d(-1). The biogas mainly consisted of methane and carbon dioxide, and the methane and carbon dioxide content in the biogas was 57-60 and 38-41%, respectively. The yield coefficient of methane production was 0.31821 CH(4) g(-1) COD removed until OLR at 33.3 kg COD m(-3) d(-1), but afterwards began to decrease. The volatile fatty acid (VFA) in the effluent mainly consisted of acetate and propionate, accounting for more than 95% of total VIA as COD, and other VIA was detected at insignificant concentrations. The mesophilic granules developed in this study showed an excellent specific methanogenic activity (SMA) at 0.91 and 1.12 g methane COD g(-1) VSS(-1) d(-1) using sucrose and acetate as individual substrates on day 200, respectively. (c) 2006 Elsevier B.V. All rights reserved.