Waste Activated Sludge

WAS Pumping System

Purpose: The WAS system provides for the controlled wasting of excess biomass from the activated sludge process.

Description: Sludge is wasted from the RAS system. Each RAS discharge line has a 4-inch branch line through which a portion of the RAS flow can be diverted to the aerobic digester. The wasting rate, the quantity of sludge wasted and the frequency of wasting are all adjustable. A motor operated plug valve in each WAS line controls the rate of flow and the duration of a wasting cycle. A magnetic flow meter in each WAS line regulates the valve operation.

Waste Activated Sludge

Excess sludge is wasted from the system to the aerobic digester using the available pressure in the RAS discharge piping. Separate WAS pumps are not used. A WAS line will branch off from each RAS line and wasting is controlled by a motor operated valve and magnetic flow meter in each WAS line similar to the control for the RAS rate. System controls permit sludge to be wasted at intervals throughout the day, with WAS discharge rate, duration and frequency all variable to allow the operator to tailor the sludge wasting times and amounts of sludge wasted to provide best overall operation. A PLC controller is used for this function with operator interface located at the main control panel.

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