Assessment of colloid filtration in natural porous media by filtration theory

Mobile colloids in groundwater aquifers can act as carriers for sorbing con taminants and thereby facilitate contaminant transport. Therefore, the remo val efficiency of two natural porous media for colloids with regard to the ionic strength of the solution and the counterion valence has been investig ated. Short-pulse experiments were conducted using fluorescence labeled lat ex colloids in order to investigate their transport behavior. The predictio ns of the filtration theory concerning the filtration of colloids were conf irmed qualitatively. The removal efficiency of a filter bed is influenced b y both the type of electrolyte and its concentration as well as the type of the porous medium. An attachment parameter alpha, which was introduced int o Happel's Sphere-in-Cell-Model, describes the dependence of the removal ef ficiency on the electrolyte concentration qualitatively. The normalization of a by the valence of the dominant counterion describes the removal effici ency independent of the kind of electrolyte.