MODELING CONTAMINANT TRANSPORT OF METAL IONS THROUGH SOIL

Abstract

Managing the waste material unscientifically is causing a lot of direct and indirect environmental problems.
Due to increase in the hydro-environmental pollution on the earth, the reactive- advective -dispersion phenomenon which
describes the reactive solute transport in the medium has got significant attention world over. Various analytical and
numerical methods are available to analyze this phenomenon under different initial boundary conditions. The objective
of this study is to model the contaminant transport of the metal ions i.e. copper and zinc through the black cotton soil
using finite layer and finite difference methods viz: Backward Time Centered Scheme (BTCS), Upwind and CrankNicolson implicit schemes. The column experiments were conducted with constant and decreasing concentrations from
the contaminant sources. The experimental results were modeled with the finite layer method using POLLUTE software
and the finite difference method with Excel spreadsheet solution. It was found that more accurate values of the transport
parameters i.e. dispersion coefficient and the distribution coefficient were obtained with finite layer method and finite
difference method using Crank-Nicolson scheme. A new Excel spreadsheet solution for the reactive-advective- dispersion
phenomenon was developed by incorporating the retardation factor in the non-reactive method proposed by Karahan in
2006. The dispersion coefficient of copper ions was observed to be lower than that of zinc ions while the distribution
coefficient of copper ions was found to be higher than that of zinc ions and the metal ion retention sequence was found
to be Cu > Zn in the black cotton soil.