Mixed waste soil washing using environmentally benign chemical solvents

Treatment of soils contaminated with radionuclides and heavy metals presents a considerable technical challenge. Soil Washing is effective for remediation of soils with a high content of large particle size material (> 90% sand and gravel). Chemical extraction methods used to date have been non-selective, yielding relatively large waste volumes compared to the volume of contaminants to be treated. Chemical extraction uses strong acids, which when neutralized also yield large volumes of waste, and in some cases hazardous material salts. Effective soil treatment requires a solvent that is selective for the contaminants to be treated, uses environmentally benign chemicals, is dilute, and preferably regenerable. This paper describes such a solvent which has been demonstrated for treating uranium, plutonium, americium, thorium, radium, barium, and lead to levels that meet current cleanup standard requirements. (author)