Effect of Elevated Temperature on Ceramic Ultrafiltration of Colloidal Suspensions

Abstract

High-temperature wastewaters and process waters in many industries have been a concern, compromising the integrity of polymeric membranes in filtration processes or requiring the temperature to be lowered for further treatments. Filtration processes employing ceramic membranes, however, can treat high temperature water owing to the inherent thermal resistance of ceramic materials, and may benefit from increases in permeate flux attributable to decreases in water viscosity at higher temperatures. In this study, the performance of a ceramic ultrafiltration membrane was evaluated for the filtration of feed solutions containing colloidal silica at temperatures between 25 and 90°C, the range encountered in various industries. Results indicated the net benefit of increasing permeate production at elevated temperatures, with a nearly 90% increase in steady-state flux from 25 to 90°C. However, this increase was lower than that observed for pure water filtration, in which the flux increase with increasing temperature was entirely attributable to viscosity reduction. Resistance-in-series model analysis and cake property characterization suggested that total fouling resistance increased as temperature increased, with physically removable cake formation as the dominant fouling mechanism.