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Air Sparging and Groundwater Recirculating Wells 27 OZONE SUPERSPARGING FOR CHLORINATED ` AND FLUORINATED HVOC REMOVAL 1� William B. Kerfoot(K-V Associates, Inc.,Mashpee, Massachusetts) ABSTRACT: Ozone supersparging with Criegee oxidation is demonstrated for chlorinated and fluorinated ethenes and ethanes. Independent testing has verified that Criegee oxidation dominates in the combined gas/aqueous fractions. No partial breakdown products have been detected in laboratory or pilot tests, The i reaction proceeds. through a low. molecular ratio of ozone to attack the central bond of the ethene molecule, when ethene derivatives are targeted, resulting in the decomposition of the halogenated fragments clearing into a carbonyl compound and a hydroxy hydroperoxide, which rapidly lose dilute hydrochloric acid (HCl) and dilute hydrofluoric acid (HFI) in the presence of water. Reactions with alkane compounds such as 1,1,1-trichloroethane (1,1,1-TCA) or chlorofluorohydro- carbons (Freon) also show rapid destruction in field testing. THEORY The KVA process is a patented technology* (the C-Sparge"m process) for in-situ treatment of VOCs in groundwater and surface water. The technology combines the unit operations of air stripping and oxidative decomposition in a single process which can be catalytically accelerated. Air and ozone are injected directly into groundwater through Spargepoints®, creating microbubbles which have a very high surface area to volume ratio. Extraction of VOCs from groundwater occurs by aqueous to gas partitioning as the bubbles rise. The ozone contained within the bubble reacts to decompose the chlorinated ethene molecule as it enters the bubble in an extremely rapid gas/liquid phase reaction. The end products are carbon dioxide, very dilute hydrochloric acid, and water. Ozone ' content in the bubble controls the rate of oxidation. The process is effective on halogenated volatile organic compounds (HVOCs) such as perchloroethene ' (PCE), trichloroethene (TCE), the dichloroethenes (DCEs: 1,1-dichloroethene, t and 1,2-dichloroethene), and vinyl chloride (VC). Gas entering a small bubble of volume 47rr3 increases until reaching an asymptotic value of saturation. If we consider the surface of the bubble to be a membrane, a first order equation can be written for the monomolecular reaction: t dx — k(Q-x) (1) r dt - >F Where x - the time varying concentration of the substance in the bubble dx/dt = the change in concentration within the bubble *U.S. patent#5,$55,775; other U.S. and foreign patents pending ; f 1 Iii