Experimental investigation of solute transport in stratified porous media

Abstract

In this study, an attempt is made to investigate the behaviour of solute transport through stratified porous media using laboratory experiments. A physical model is constructed to represent stratified porous media consisting of an advective region sandwiched between two non-advective regions. Pulse of tracer was injected at the inlet of the sand layer situated in between the clay matrix of the experimental model, and samples of tracer were collected at the other end of the model. An implicit finite-difference numerical technique is used to solve advective dispersive transport equations, including equilibrium sorption and first-order degradation constant for reactive transport through stratified porous media. A numerical model is used to simulate the breakthrough curves of experimental data of chloride and fluoride. It is seen that the peak of breakthrough curves is higher for the non-reactive solute compared to that of the reactive solute. The observed breakthrough curves were also found to be skewed in shape for solutes in stratified porous media. The numerical model was also found to be more sensitive to the value of transverse diffusion during simulation of experimental breakthrough curves. Finally, the values of effective diffusion coefficient and retardation coefficient are estimated by simulation of experimental breakthrough curves.

Keywords:

• solute transport experiment
• numerical model
• breakthrough curves
• diffusion.

Acknowledgments

This work was supported by the Department of Science and Technology New Delhi under research grant number DST-456-CED.