The Rheology of Activated Sludge

Rheological measurements can be used to express basic physical properties of activated sludge. Knowledge of such properties, and the effect of biological variables on them, is essential for understanding of the fundamental factors controlling flocculation, sedimentation, and consolidation of activated sludge. Rheological measurements also show promise as guides to the operation of activated sludge plants. Rotational viscometers used for investigating the rheology of activated sludge must be compatible with the nature of the sludge. Viscometer surfaces must be roughened, a large sample width must be used, and care must be taken to avoid turbulent flow. Activated sludge is a plastic material and is thixotropic.