TRANSPORT OF REACTIVE CONTAMINANTS THROUGH POROUS MEDIA-AN EXPERIMENTAL STUDY

Abstract

Detailed experimentation program was undertaken to determine the adsorption parameters as well as to simulate the flow condition through the soil column. In the present study, experiments were performed in order to investigate the concentration profiles through one dimensional soil column using chemical tracers such as chloride and fluoride. From literature it is also well known that fluoride chemical is reactive. Once it occurs in contact of soil media, it is adsorbed on the soil surface. While conducting experiment through soil column, it seen that the pore velocity is higher in case of natural soil and fine sand. It means that movement of chemical is very fast and fluoride chemical moves very fast along water. It was observed that the behavior of temporal concentration of fluoride chemical is similar to chloride chemical. Therefore, value of retardation factor has been taken one. Implicit finite difference ' numerical technique .has been used to get the solution of governing equation for solute concentration in solution phase. This numerical model has been used to simulate observed experimental data for both cases of fine sand and natural soil. It was found that this model was able to simulate the experimental results satisfactorily in fine sand and natural soil columns , The experimental sorption data has been fitted using four linear Langmuir-1, 2, 3 and 4 and Freundlich isotherm models. In the case of fine sand, it was observed that Langmuir-2 linear isotherm gives better fit to the experimental data, with higher coefficient of determination as compared to other Langmuir linear isotherms and Freundlich. Further, in the case of clay, it has been observed that the Freundlich and langmuir-2 linear isotherm provides a better fit to experimental data as compared to all other forms of Langmuir isotherms. Finally, Langmuir-1 linear isotherm can be used for the case of natural soil.