Anaerobic Treatment of Low-Strength Domestic Wastewater Using an Anaerobic Expanded Bed Reactor

A significant potential exists to lower energy consumption and reduce sludge production by incorporating anaerobic processes into wastewater treatment trains. The specific treatment arrangement studied in this case is the anaerobic treatment of primary clarifier effluent of wastewater treatment plants. Anaerobic batch assays showed that the primary clarifier effluent used in this study was ultimately 90% or more anaerobically biodegradable, thus suitable for anaerobic treatment. The anaerobic expanded bed reactor (AEBR) performed well over a wide range of influent CODs and temperatures, especially under severe conditions (5°C and 50 mg/L influent COD). The most efficient treatment was obtained with HRTs of three to six hours and influent COD of approximately 150 mg/L. Start-up of the reactor took about 60 days at 30°C and 80 days at 20°C.