90 



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 relevant for dioxin-contaminated sediments because PCBs and dioxins are structurally 



similar. 



The ARCS technologies that have been successful in the treatment of PCB- 

 contaminated sediments are thermal desorption, solvent extraction, chemical 

 transformation, and sediment washing. Of these four treatment types, only chemical 

 transformation results in a net destruction of the contaminant of concern. The other 

 three technologies extract or separate the contaminants from the bulk of the 

 sediments, concentrating them in a much smaller volume that can be more easily 

 treated to complete destruction. 



In addition to these technologies, there is also the potential for biodegradation, or 

 the use of natural or cultured microorganisms to destroy persistent organic 

 contaminants. The ARCS Program was able to successfully demonstrate laboratory 

 destruction of PCBs in sediments from three Great Lakes rivers. Research in this area 

 has been limited, however. 



The technologies demonstrated at the pilot scale by the ARCS Program are all 

 well-developed and are at a point where scale up is possible. Thermal desorption 

 units have been used to remediate a PCB-contaminated sediment Superfund site in 

 Waukegan Harbor, Illinois. The sediment washing process, successfully 

 demonstrated on low-level (i.e., 2ppm) PCB contaminated sediments in the Saginaw 

 River and Bay, has been used on a full-scale basis in several European sediment 

 remediation projects, and on several upland contaminated soil projects in the U.S. 



