Adsorptive Chromium Removal by Some Clayey Soil for Abatement of Tannery Waste Pollution

Leachate migration from uncontrolled municipal and industrial solid waste disposal sites leads to significant subsoil and groundwater pollution. In order to combat this geo-environmental problem, landfill construction must be done in such a way that the solute transport along with leaching is minimal and significantly attenuated. A laboratory-scale investigation was carried out to explore the suitability of different types of clayey soils collected from a leather tannery, as well as from a nearby area located in West Bengal, India. These clayey soils were examined in terms of acting as a liner material in a landfill near a tannery waste disposal site to prevent Cr migration into the surrounding environment. The existence of ${\mathrm{Cr}}^{6+}$ in excess of the permissible limit was found in soil and water samples collected from the sites. The compaction study revealed that use of these soils as a compacted clay liner could achieve the desired permeability as high as $1\times {10}^{-7}\mathrm{cm}/\mathrm{s}$. The batch kinetics study showed a reasonable ${\mathrm{Cr}}^{6+}$ uptake capacity of the soil (75–90%) in equilibrium conditions. The breakthrough adsorption study was also carried out in a large-scale tank and in a vertical column, which showed a good metal (${\mathrm{Cr}}^{6+}$) adsorption capacity of soil.