The conventional activated sludge system comprises an aeration tank and a clarifier. Aerobic biomass degrades COD in the aeration tank. The mixed liquor (ML) in the clarifier is separated into a water phase and a concentrated ML by sedimentation. The clarified water overflows weirs at the top of the clarifier whereas the sludge (biomass) is removed at the bottom. The major part of the biomass is recycled to the aeration tank to maintain the required amount of biomass in the system. Redundant biomass, produced by growth of microorganisms due to COD degradation, is withdrawn from the sludge stream and discharged to a storage tank or further sludge treatment facilities.