Effect of mineral colloids on virus transport through saturated sand columns

Studies have indicated that colloids are capable of adsorbing and enhancing the transport of a variety of contaminants in soil, fractured rocks, and g round water. The purpose of this study was to determine the role of mineral colloids on the fate and transport of viruses through porous media. Experi ments were conducted to examine the influence of several mineral colloids [ kaolinite, Ca-montmorillonite (Ca-M), and Na-montmorillonite (Na-M)] on the movement of a bacteriophage (MS2) through sand columns under saturated flo w conditions. Input solution containing MS2 and Br- tracer was applied to t he column as a pulse Function while colloids were introduced as a step func tion. Effluent samples were collected in a fraction collector and analyzed for Br, virus, and colloids. The convection-dispersion equation (CDE), part ially calibrated with the transport parameters measured from the Br- signal , was used to evaluate the transport characteristics of both the virus and colloids. Transport of both the colloids and MS2 through sand columns was d escribed well by the CDE when a first-order kinetic removal process was ass umed. The bacteriophage MS2,vas adsorbed by colloids to various degrees and in the order of fine Na-M > coarse Na-M > Ca-M similar to kaolinite. The a mount of colloids transported through the columns followed the same order. The Na-M greatly enhanced MS2 transport through the sand columns and the ef fect was more significant when the clay particles were ground into smaller sizes. The extent of colloid-facilitated MS2 transport was clearly correlat ed with the extent of colloid transport and the number of viruses adsorbed to colloidal particles. To our knowledge, this study demonstrates for the f irst time the possible effect of colloids in Facilitating virus transport t hrough porous media.