Enhanced Washing by Particle Dispersion – Chemical Extraction for Soil Contaminated with Heavy Metal and Petroleum Hydrocarbon

Abstract

The basic idea of soil washing was started from a physical approach based on mining and mineral processing principle. After 90s, various chemical reagents were tried to enhance the washing efficiency based on the reactions such as chemical extraction, and solubilization. However, previous researches have only focused on the chemical aspects of desorption mechanism without considering the microscopic characteristics of fine-grained soils which can be a great influence factor to washing reactions. A novel soil washing equipment for fine grained soil applying physical forces to contaminated soil to supply sufficient impact force to disturb the microstructural aggregation and/or loosen the binding between contaminant and soil particles. Field soils contaminated by heavy metals from an old refinery site and dredged material in South Korea was investigated to evaluate the contaminant removal efficiency. Three kinds of washing methods including physical desorption, chemical solubilization, and the combined effort were performed in this study. The best removal efficiency was found in the combination of physical and chemical treatments in every experiment cases. The test results show contaminant removal efficiency in soil washing system can be enhanced using physical forcing system.