A Combination of the Activated Sludge Process with Fixed Film Biomass to Increase the Capacity of Waste Water Treatment Plants

Abstract

The volume of the activated sludge aeration tank is influenced by f/m ratio and attainable biomass concentration. Increase of biomass results in smaller tank volume. In case of overloaded plants restoration may be achieved by increase of biomass instead of construction of further tank volume. Pieces of porous plastic media filled into ordinary compressed air aeration tanks may serve as fixed film biomass support. By this method biomass concentration in the tank may be increased to two or three times normal values. At the same time the sludge volume index of the activated sludge flocs still present in the aeration tank is improved. Better sedimentation and thickening of the activated sludge occurs because smaller quantities of flocs are passed to the final clarifiers. Results of tests with different types of waste water in semi-technical scale pilot plants as well as in existing plants of different sizes are presented.