Evaluation of instability and performance of an upflow anaerobic sludge blanket (USAB) reactor treating high-strength ice-cream wastewater

摘要

The anaerobic digestion of high strength ice-cream wastewater was studied in an upflow anaerobic sludge blanket reactor. The profiles of the reactor, i.e. the distributions of the substrate concentration and pH under different operating conditions, were determined. From the concentrations of substrates measured at various levels above the bottom of the reactor, two reaction stages, namely acidogenesis and methanogenesis, were distinguished. The instability caused by high influent concentration was interpreted as the accumulation of volatile fatty acids in the acidogenic stage beyond the assimilative capacity of the methanogenic stage. A range of stable operating conditions was predicted from the results of the profile measurements. The optimal influent chemical oxygen demand concentration was between 11 and 23 g/l at a hydraulic retention time of 5 days for system stability.