Clarifier with influent well scum removal

Abstract

A clarifier in a sewage treatment process includes efficient scum removal within the influent well, with discharge of the scum and other floatables as a dedicated waste stream separate from return activated sludge and biological scum collected in the clarifier. Foam contained within the influent well may be treated with bacteria-killing agents or with anti-foaming agents. In one embodiment the scum removal system has an inclined scum ramp at the leading edge of each of two scum removal troughs, with a forward edge below the liquid surface. The scum troughs pass through an arc of rotation, building up scum, which accumulates and is pushed forward by the scum ramp. At least once per revolution, the moving scum ramp approaches a stationary scum surface blade that extends partially under the liquid surface and provides a barrier to the forwardly pushed scum. This blade contacts and slides up the ramp, sweeping the is scum up the ramp and into the scum trough. The described arrangement greatly reduces the amount of free water with the collected effluent scum as compared to the typical designs and permits scum and gross floatables from the influent well to be trapped and contained and discharged and treated separately.

Dependencies are inferred from the claim text.