Water and Environmental Research Center
Seminars
30 October 2009
Surface Water Quality and Microfiltration Membrane Material Properties: Effects on Membrane Fouling
Erin McDonald
Credit: Peter Prokein 2008
Erin McDonald collecting Toolik Lake water for further study.
Abstract
Many communities in rural Alaska have to rely on surface water as a drinking water source due to limited availability of groundwater. These surface waters often have a high organic content, which is difficult to remove with conventional treatment methods. Heavy chlorination is required, resulting in the formation of disinfection byproducts. Membrane filtration produces high quality effluent, thereby reducing the potential for disinfection byproduct formation. However, fouling of membranes by organic matter can reduce flux and adversely impact process economics. Successful application of membrane filtration to surface water sources is dependent on the minimization of membrane fouling. In this study, a bench scale and pilot scale system were used to investigate fouling characteristics of different influent compositions and different membrane materials. The bench scale, dead-end filtration system was used to quantify and compare fouling characteristics by treated water flux. Seasonal samples from a tundra pond and river were tested with a variety of membrane materials selected to represent a range of material properties. Seasonal samples were also pretreated to represent a broader spectrum of influent characteristics by varying the pH and isolating the dissolved fraction. The bench scale system is limited in its representation of a membrane system’s hydraulics and operation. The pilot scale system was used to quantify system performance with seasonal influent variation and membrane age, measured by transmembrane pressure and effluent quality. The relationship between influent quality and fouling characteristics guides the selection of water sources, seasonal pretreatment options and operational considerations. Differences in membranes’ material properties affect the degree of fouling and thereby the flux across the membrane. This knowledge suggests the most appropriate membrane material for a specific source water quality.