Regimes for zone settling of waste activated sludges Original Research Article

Regimes for the zone settling of the waste activated sludges has been investigated experimentally. Channelling in sludge was observed in the high concentration test which enhanced the settling. In low concentration tests, large floc aggregates would form spontaneously from an originally macroscopically homogeneous settling sludge, which also enhanced the settling. Only in the intermediate concentration range could the Richardson-Zaki type correlation be adequately applied. Empirical criteria for differentiation of settling regimes were proposed.