PILOT-SCALE FIELD TEST OF SOLUBILITY ENHANCED IN SITU CHEMICAL OXIDATION OF VOLATILE ORGANIC CONTAMINANTS

The goal of this study is to determine the effectiveness of a new integrated desorption-oxidation process for the remediation of groundwater and sediments contaminated with volatile organic compounds (VOC). Contaminant availability is a major limiting factor for in situ chemical oxidation (ISCO) remediation of VOC at many sites. In general, contaminants with higher aqueous solubilities are more accessible for oxidation relative to less soluble compounds. In this study, the potential of using a solubility enhancing agent was investigated to overcome this limitation and increase the remediation efficiency of ISCO. Specifically, this study examines the combination of a peroxone (O₃ + H₂O₂) activated sodium persulfate (Na₂S₂O₈) system (OxyZone®, EnChem Engineering) and the solubility enhancing agent hydroxypropyl-beta-cyclodextrin (HPCD). HPCD is a cyclic sugar with a hydrophilic exterior and a hydrophobic cavity. HPCD forms water-soluble inclusion complexes in which a non-polar guest compound is encapsulated in the hydrophobic cavity of the host HPCD molecule. Through the formation of inclusion complexes HPCD can significantly increase the apparent solubility of non-polar contaminants, including VOC, and greatly promote their desorption from soil matrix. The field test was conducted at a VOC contaminated former fire-training area. The major contaminants identified at the site are 1,1,1-trichloroethane (1,1,1-TCA), dichlorobenzenes (tDCB) and tetrachloroethene (PCE). Full scale field testing began in April 2013 and consisted of two major injection events. Injections finished in August 2013 with post treatment sampling slated to continue through December 2013. To the authors knowledge this is the first pilot-scale field test of HPCD enhanced ISCO and we will present the latest results of this study.