(632b) Electrostatic Impacts On Fouling of Microfiltration Membranes

Over the last two decades, PNNL has been working on separation processes for the Waste Treatment Plant and in particular cross flow filtration. Recent work at the laboratory has focused on determining the mechanisms of reversible and irreversible depth fouling of the filter media for this technology. Fundamental particle properties play an important role in filter/membrane depth fouling and the formation of solids cakes on the filter surface. With respect to depth fouling, penetration of the porous network is governed by particle size and particle filter interactions are governed by standard DLVO (Derjaguin, Landau, Verwey, and Overbeek.) interactions. The surface charge of the filter and particle play a significant role in how strongly the filter fouls (and if that fouling is reversible). When the filter surface and particles have the same charge, fouling is expected to be minimal. When the filter and particles have opposite charges, fouling is expected to be strong. Because the filter medium and the particles comprising the dispersion are typically different materials, charge disparity between the two is likely. However, surface charge is also affected by pH and ionic strength of the slurry supernatant. To advance a fundamental understanding of filter fouling dynamics, the impacts of particle interactions (as governed by zeta potential) were tested and incorporated into existing models for filtration.