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United States Environmental Protection Agency
National Risk Management Research Laboratory
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U.S. EPA Superfund Innovative Technology Evaluation (SITE) Program
Acid Extraction Treatment System (AETS)
Center for Hazardous Materials Research

Abstract

The AETS technology extracts heavy metal contaminants from soils. Soils are screened to remove particles > 4 millimeters in diameter; typically, these particles require only a water or detergent rinse to remove attached fine particles containing contaminants. The particles less than 4 mm are scrubbed with an attrition scrubber to break up agglomerates. Hydrochloric acid is added to the extraction unit; residence times vary from 10 to 40 minutes. The soil extractant mixture is continuously pumped out of the mixer to hydrocyclones that separate the solids and liquid. When the extraction is complete, the soils are rinsed with water to remove metals and acid. The extraction fluid and water are regenerated to remove metals and reform the acid. Heavy metals are concentrated for recovery. Soils are mixed with lime to neutralize any residual acid. No wastewater streams are generated. Under the Emerging Technology Program, a bench-scale system was tested using soils from 4 Superfund sites and a synthetic soil matrix. AETS reduced Toxicity Characterization Leaching Procedure (TCLP) metals to below the RCRA limit and total metals to below the California limits.

 

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Posted July 12, 1999

 

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