Photodegradation for decontamination of polychlorinated aromatics and related compounds

Prolonged industrial activity involving the production or application of toxic chemicals led to the contamination of various sites in the United States. One such activity is wood preservation. Several organic and inorganic chemicals have been used for the purpose. The organic wood treatment chemicals (creosotes, chlorinated phenols and associated chlorinated dioxins) are highly toxic and persistent environmental contaminants. Release of these chemicals have caused severe contamination in many locations. Desire to remove and destroy these contaminants has resulted in a number of remediation technologies. Earlier studies have shown photodegradation to be the major natural pathway for decontamination. However, photodegradation is limited to regions that allow transmission of sunlight, which amounts to a fraction of a millimeter in soil. One way to overcome this limitation is solvent extraction coupled with photodegradation. The results of laboratory and field experiment show that soil decontamination can be accomplished with this combination. The most promising results were obtained with the use of binary solvent mixtures, which removed 90% of the contaminants in the contaminated soil at a wood treatment site. The technique with efficient solvent recovery and reuse of solvent should provide an economical option for remediation of contaminated soils at wood treatment sites.