MODEL OF CONTAMINANT TRANSPORT IN POROUS-MEDIA IN THE PRESENCE OF COLLOIDS APPLIED TO ACTINIDE MIGRATION IN COLUMN EXPERIMENTS

We simulate column experiments of europium migration in humic-rich gro undwater performed with different Darcy velocities to investigate the predictive capability of colloid-facilitated transport models for acti nides. The simulation results indicate two retention mechanisms:. sorp tion of dissolved contaminants and filtration of colloidal contaminant s by the matrix. These interaction processes, which determine the brea kthrough curves and their tailing behavior, are kinetically controlled . Sorption constants are derived from batch experiments. Sorption rate s are obtained by the simulation and are compared with the values of t he filtration rate predicted by the colloid filtration theory.