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FIELD STUDY: IN SITU OXIDATION OF 1,4-DIOXANE WITH OZONE AND HYDROGEN PEROXIDE
Citation:
SADEGHI, V. M., D. J. GRUBER, E. YUNKER, M. A. SIMON, AND C. G. SCHREIER. FIELD STUDY: IN SITU OXIDATION OF 1,4-DIOXANE WITH OZONE AND HYDROGEN PEROXIDE. Presented at Fifth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, May 22 - 25, 2006.
Description:
A pilot-scale field evaluation is underway to assess the effectiveness of in situ oxidation (using ozone with and without hydrogen peroxide) for remediation of 1,4-dioxane and chlorinated volatile organic compounds in groundwater at the Cooper Drum Company Superfund Site located in South Gate, Los Angeles County, California. The use of ozone/hydrogen peroxide for in situ treatment is being evaluated specifically because 1,4-dioxane is difficult to treat: it is resistant to aerobic and anaerobic biodegradation, it is not volatile, and it is not adsorbent. Whereas advanced oxidation processes with ozone and hydrogen peroxide (and/or UV light and/or titanium dioxide) are commonly used for ex situ treatment of dioxane-contaminated wastewater, in situ application of the process for remediation of this chemical in groundwater is innovative. The destruction of 1,4-dioxane is believed to be enhanced by formation of the hydroxyl radical which is produced by the reaction of ozone and hydrogen peroxide. However, laboratory testing prior to the field test demonstrated that ozone, alone, was as effective as ozone combined with hyrogen peroxide at destroying 1,4-dioxane present in site soil and groundwater. This was an unexpected (and welcome) observation which will be further evaluated in the field application of the technology. The most challenging aspect of the field application is to ensure that ozone and hydrogen peroxide are effectively delivered to the contaminated plume areas, and that they meet and react to form the hydroxyl radicals. Use of ozone alone would significantly reduce the complexity of the application because the requirement that ozone and hydrogen peroxide meet and react would be removed; furthermore, it would be easier to diffuse/disperse gaseous ozone into the formation.
The ozone/hydrogen peroixde generation and delivery systems were installed in mid-July and the system has been operating continuously since that time. In this initial operation phase, ozone is being injected into the subsurface. The first round of sampling after startup of the field test is scheduled for late July. Additional periodic sampling is to be performed for several months. Injection of liquid hydrogen peroxide in conjunction with ozone will be evaluated after review of these sampling results. An evaluation of the effectiveness of ozone/hyrogen peroxide in remediating the recalcitrant compounds present in site groundwater will be presented after the system has operated for a sufficient period of time and all sampling results are evaluated.