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 ground water. The purpose of this study was to determine the role of mineral colloids on the fate and transport of viruses through porous media. Experiments 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 flow conditions. Input solution containing MS2 and Br- tracer was applied to the column as a pulse Function while colloids were introduced as a step function. Effluent samples were collected in a fraction collector and analyzed for Br, virus, and colloids. The convection-dispersion equation (CDE), partially 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 described well by the CDE when a first-order kinetic removal process was assumed. 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 amount of colloids transported through the columns followed the same order. The Na-M greatly enhanced MS2 transport through the sand columns and the effect was more significant when the clay particles were ground into smaller sizes. The extent of colloid-facilitated MS2 transport was clearly correlated with the extent of colloid transport and the number of viruses adsorbed to colloidal particles. To our knowledge, this study demonstrates for the first time the possible effect of colloids in Facilitating virus transport through porous media.