Emulsified Zero-Valent Nano-Scale Iron Treatment of Chlorinated Solvent DNAPL Source Areas.

摘要

Chlorinated solvents are present in groundwater at an overwhelming number of Department of Defense (DoD), Department of Energy (DoE), and related contractor sites. A significant number of these sites have VOCs present as free- phase dense non-aqueous phase liquids (DNAPLs) that will act as a long-term source of VOCs to groundwater. Due to the slow dissolution of solvents from residual or pooled DNAPL source areas, conventional treatments such as pump-and- treat serve solely as containment technologies and require long operational periods (i.e., decades or longer) to satisfy the need for protection of human health and the environment, incurring high operation and maintenance (O&M) costs over that period. Recently, a small-scale field pilot test of emulsified zero-valent iron (EZVI) was conducted under the National Aeronautics and Space Administration (NASA) Small Business Technology Transfer (STTR) program to assess the ability of this technology to treat a Trichloroethene (TCE) DNAPL source zone. The pilot test showed promising results as a method for significantly reducing both mass and flux from DNAPL source zones. However, additional field demonstration research is required to improve the EZVI delivery approach, clarify the relative degradation contributions of the zero- valent iron (ZVI) versus biodegradation promoted by the emulsifying agents (completed laboratory evaluation; Geosyntec, 2006a), and validate the technology for widespread use for DNAPL source zone treatment at DoD and related private sectors sites. Geosyntec Consultants Inc. (Geosyntec) and NASA conducted a technology demonstration program evaluating the use of EZV. This Final Technical Report presents the approach, methodology and results of the EZVI field Demonstration/Validation.