Heavy metals such as chromium, cadmium, lead, and nickel are often found to have contaminated soils and groundwater at metal finishing shops, landfills, and manufacturing facilities. Currently, the most commonly used remedial technique is to remove the soil from the site for off-site fixation. Because of the high cost of transportation of the soil and diminishing capacity of hazardous waste landfills, more emphasis is being given to methods that can be applied to soils for in-situ treatment. Some studies have been performed to determine the best reagents to apply to the soils to mobilize and remove heavy metals. Unfortunately, many of these studies focused on the use of chelating agents. While chelating agents are effective in removing metals from soils, the leachate generated cannot be treated by most commercially, available wastewater treatment systems which are found at many metal finishing operations and manufacturers. A method has been developed, called sequential extraction, which removes the metals sequentially from the extractable, organically occluded, and iron/manganese occluded portions of the soil. This method does not use chelating agents, and has been used successfully in laboratory scale studies. The purpose of this Phase I research is to apply sequential extraction to column scale tests. The research will also investigate manipulating the concentration of the chemicals used in sequential extraction so that lower concentrations of chemical reagents can be applied in situ, which would lower impact of the reagent on the environment and workers should a spill of the material occur. This will also require column testing of contaminated soil samples.Anticipated Results /Potential Commercial Applications as described by the awardee:The DOE, the Federal Government, and the private sector are all affected by the problems associated with the contamination of soils and groundwater by heavy metals. Because of the high costs and risks associated with off-site treatment, an in-situ method for treatment of soils contaminated with heavy metals needs to be developed. This research is aimed at providing a method for treating soils contaminated with heavy metals in situ. This method can be applied at hazardous waste sites, Resource Conservation and Recovery Act sites, and Superfund sites in a safe and economical manner.
