SOLUTE TRANSPORT THROUGH HOMOGENEOUS AND HETEROGENEOUS POROUS MEDIA EXPERIMENTAL STUDY

Abstract

Solute transport in subsurface system is affected by physical, chemical and properties of soil media. Assuming equilibrium interactions between solutes in the liquid and solid phases, advective dispersive transport equation is used to describe one-dimensional solute transport through porous media. In this study, soil column experiments were carried out in the lab to investigate the behavior of solute through homogeneous and heterogeneous soil column experiment, respectively. The length of both columns was taken as 600 cm respectively. Chloride ion was used as conservative tracer and fluoride and nitrate were considered as neoconservatives tracers. Implicit finite difference numerical technique was used to get the solution of advective dispersive transport equation with equilibrium sorption and first order degradation constant. Both pulse and constant concentration type boundaries conditions were used during simulation. Experimental breakthrough curves of chloride were compared between homogeneous and heterogeneous soil column experiment. It is seen that the experimental breakthrough curves were smooth and uniform in case of homogenous soil column as compared to heterogeneous soil column experiment. Excellent agreement was obtained between observed and simulated breakthrough curves. It is seen that the dispersivity is distance dependent along the flow direction through soil column. Finally, numerical model was used to simulate the data experimental breakthrough curves of chloride, fluoride and nitrate. It was attempted to estimate the value of dispersion coefficient and retardation factor during simulation. The estimated values of dispersion coefficient and retardation factor during simulation of experimental breakthrough curves and value pore water velocity during experiment might be useful in design of solid waste disposal system.