NONREACTIVE SOLUTE TRANSPORT WITH MICROPORE DIFFUSION IN AGGREGATED POROUS-MEDIA DETERMINED BY A FLOW-INTERRUPTION METHOD

Water-saturated column experiments were conducted under conditions of steady flow. The columns were packed with artificial porous material having a distinctly unimodal or bimodal pore size distribution. Experimental breakthrough curves were modelled with the convection-dispersion equation and a bicontinuum spherical diffusion model. Using the convection-dispersion equation for modelling the transport of solute in aggregated porous media, a quadratic relation was found between the dispersion coefficient and the pore velocity. Column experiments in which the flow was interrupted showed the large impact of micropore diffusion. By using this method the contributions of macro- and micropore transport mechanisms can be separated. A sensitivity analysis for such experiments is given.