Development of the electrode assisted soil washing process
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Contaminants in soils containing a high percentage of silt- and clay-sized particles typically are strongly adsorbed onto the soil and are very difficult to remove. State-of-the-art technologies find it very difficult, if not impossible, to apply soil washing to these contaminated soils. However, a newly patented Electrode Assisted Soil Washing (EASW) process appears to be effective in removing petroleum hydrocarbons (gasoline, diesel, crude oil, etc.), chlorinated hydrocarbons (pentachlorophenol), and heavy metals (Pb, As, Cd, Zn) from contaminated soils made up of a high percentage of clay and silt. The EASW process produces a washed soil material that meets site-specific regulatory requirements which allow the washed soil to be returned to the site without further treatment. Furthermore, the contaminated water generated by the process can be treated with standard methods. The EASW process can be used alone, or it can be used in combination with other soil-washing methods. In the latter case, the EASW process is particularly effective in the treatment of contaminated fines streams generated by other soil-washing techniques. The EASW process has been developed to operate in a batch mode as well as in a continuous mode. Initially, laboratory contaminated soils (diesel and crude oil in Lubbock topsoil) were used to test the EASW process. Later, authentically contaminated soils from well documented sites in New Jersey (from a petrochemical loading dock) and the Gulf Coast were also washed using the EASW process. A complete anaylsis of the wastewater generated in the process was also done.