The pollution of soils by toxic metals like lead, arsenic, chromium, copper, nickel and zinc has significant economic, environmental and social impacts in industrialized countries. In the last decade, different physical, chemical, biological and electrochemical technologies have been developed to solve this problem. The physical separation technologies for metal-polluted soil remediation are mainly screening, hydrodynamic classification, gravity concentration, froth flotation, magnetic separation, electrostatic separation, and attrition scrubbing. The chemical soil treatments use different extractants like acids or bases, surfactants, salts and redox agents to extract metallic pollutants from soils. The metal-polluted soils can also be rehabilitated using biological means like phytoextraction techniques, the use of biosurfactants and bioleaching processes. Finally, much research has been undertaken in recent years concerning the application of electrotechnologies for soil decontamination, including electrokinetic and chelator-enhanced electrokinetic extraction techniques. This paper covers recent developments in the field of technological options to remove toxic metals from polluted sites based on 16 patents analyzed.
Keywords: Soil, metal, leaching, electrokinetic, phytoremediation, phytoextraction, surfactant, biosurfactant, flotation, solvent
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