Solubility Enhanced in Situ Chemical Oxidation of VOC Contaminated Soil and Groundwater: Pilot Field Test

In situ chemical oxidation (ISCO) is an increasingly accepted treatment technology for groundwater and sediments contaminated with hydrophobic volatile organic compounds (VOC). ISCO reactions occur predominantly in the aqueous phase and as a result ISCO is more effective at treating dissolved phase contaminants than sorbed compounds or dense non-aqueous phase liquids (DNAPLs). We hypothesize that it may be possible to increase the efficiency of ISCO by using a solubility enhancing agent which increases the mass of aqueous phase VOC that is available for oxidation. In this pilot scale field test we studied the solubility enhancing agent hydroxypropyl-beta-cyclodextrin (HPCD) in combination with an advanced oxidation process at a former fire training area. The oxidant used in this study is a perxone (O₃ + H₂O₂) activated sodium persulfate (Na₂S₂O₈) mix known as OxyZone®. Major pollutants at the site include VOC such as 1,1,1-trichloroethane (1,1,1-TCA), dichlorobenzenes (tDCB), and tetrachloroethene (PCE). Other contaminants include the solvent stabilizer 1,4-dioxane and perfluorinated compounds (PFC), which were widely used as flame retardants. The most abundant PFC detected at the test site is perfluorooctanesulfonic acid. Preliminary results suggest that HPCD facilitated the transfer of VOC to the aqueous phase and their subsequent destruction by ISCO. The results of the solubility enhanced treatment of VOC, as well as 1,4-dioaxne and PFC co-contaminants, will be presented.