Abstract |
The return sludge flow, or more precisely, the clarifier sludge flow which includes both return sludge and excess waste sludge flows, should be adjusted to meet measurable process requirements. Attempts to maintain arbitrary return sludge flow percentages of the wastewater flow will seldom achieve optimum sludge quality and process balance. The results of the one-hour mixed liquor settlometer test, the 15-minute mixed liquor and return sludge centrifuge test, and the final clarifier sludge blanket test reading provide the basic data for simple calculation of the clarifier sludge flow rate needed to maintain or restore process equilibrium. |