Upflow Sludge Blanket Filtration (USBF): an Innovative Technology in Activated Sludge Process

Abstract

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, BOD₅= 250 mg/l and TSS= 1 mg/l).
Results: On the average, the treatment system was capable to remove 82.2% of the BOD₅ 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.