Groundwater Remediation Using a Chlorine/Ultraviolet Advanced Oxidation Process
Tuesday, May 6, 2014: 1:40 p.m.
Platte River Room (Westin Denver Downtown)
Advanced Oxidation Processes (AOPs) use a variety of means to generate hydroxyl radicals, potent oxidants which can rapidly degrade a large variety of organic chemicals. AOPs are commonly used in groundwater remediation applications to remove chemicals such as 1,4-dioxane, methyl-tert
-butyl ether (MTBE), or trichloroethylene (TCE) from a contaminated water source. Combining hydrogen peroxide and ultraviolet light (H2
/UV) is the most commonly used AOP, and this process works through the action of UV light on hydrogen peroxide, which produces hydroxyl radicals. While H2
/UV AOPs are effective, they are often costly due to the high price of hydrogen peroxide, the low amounts of hydrogen peroxide actually used in the process, and the need for quenching residual hydrogen peroxide after AOP treatment is complete. Recently, researchers have been exploring the combination of aqueous chlorine and ultraviolet light (Cl2
/UV) as an alternative AOP. Similar to H2
/UV produces hydroxyl radicals from the photolysis of aqueous chlorine. Laboratory testing had indicated that, in some situations, Cl2
/UV AOPs are expected to be far less expensive than a comparable H2
/UV process. Until now, such observations had not been corroborated through field studies, where parameters outside the control of a laboratory setting can impact AOP treatment outcome.
This presentation will describe pilot study results comparing H2O2/UV and Cl2/UV AOPs for the removal of TCE from contaminated groundwater. These studies were conducted on the full scale operations of two Ground Water Extraction and Treatment facilities operated by Aerojet-Rocketdyne, and compared the TCE removal efficacy of the in-place H2O2/UV AOP with Cl2/UV AOP. Data was then used to determine the expected operational costs of a full scale Cl2/UV AOP treatment process. The impact of Cl2/UV AOP on the photolytic removal of N-nitroso-dimethylamine (NDMA) and the acute toxicity of the AOP effluent water were also explored.