Temperature Effect on Rheology of Sludges

Abstract

The effects of temperature on the rheology of five municipal wastewater sludges was examined using a Stormer rotational viscometer. The sludges had total solids concentrations ranging from 2.0 percent to 6.6 percent by weight. The temperatures utilized were 10°C, 15°C, 20°C, and 25°C. Two types of non-Newtonian models, the Bingham plastic and the pseudoplastic, were used in the analysis. The results demonstrate that temperature has a significant effect on the viscosity of wastewater sludges. The apparent viscosity of the plastic and pseudoplastic models were found to vary with temperature in a fashion analogous to the viscosity of Newtonian fluids. The yield stress and consistency index both vary exponentially with temperature. The coefficient of rigidity for the plastic model and the flow behavior index for the pseudoplastic model were found to be essentially independent of temperature.