Rheology of Activated Sludge in Membrane Bioreactors

Abstract

Activated sludge rheology plays a major part in the design of membrane bioreactors (MBR). In this paper, the rheological behavior of activated sludge samples taken from nine different MBR was investigated. All samples showed strongly pseudoplastic behavior. The apparent viscosity was found to be dependent on the applied shear rate and, further, on the particle concentration. Two mathematical approaches, the Ostwald equation and the Hershel-Bulkley equation, were compared to model the rheological behavior of the investigated sludges.