upflow sludge blanket filtration (usbf): an innovative technology in activated sludge process

background: a new biological domestic wastewater treatment process, which has been presented these days in activated sludge modification, is upflow sludge blanket filtration (usbf). this process is aerobic and acts by using a sludge blanket in the separator of sedimentation tank. all biological flocs and suspended solids, which are presented in the aeration basin, pas through this blanket. the performance of a single stage usbf process for treatment of domestic wastewater was studied in laboratory scale. methods: the pilot of usbf has been made from fiberglass and the main electromechanical equipments consisted of an air com­pressor, a mixing device and two pumps for sludge return and wastewater injection. the wastewater samples used for the experiments were prepared synthetically to have qualitative characteristics similar to a typical domestic wastewater (cod= 277 mg/l, bod 5 = 250 mg/l and tss= 1 mg/l). results: on the average, the treatment system was capable to remove 82.2% of the bod 5 and 85.7% of cod in 6 h hydraulic re­tention time (hrt). at 2 h hrt bod and cod removal efficiencies dramatically reduced to 50% and 46.5%, respectively. conclusion: even by increasing the concentrations of pollutants to as high as 50%, the removal rates of all pollutants were re­mained similar to the hrt of 6 h.