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

Abstract : 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 volatile organic compounds (VOC) present as free-phase dense nonaqueous phase liquids (DNAPLs) that will act as a long-term source of VOC to groundwater. Due to the slow dissolution of solvents from residual or pooled DNAPL source areas, conventional treatments such as pump-and-treat (P&T) 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. Emulsified zero-valent iron (EZVI) is an innovative remediation technology that can be used to enhance the destruction of chlorinated DNAPL in source zones by creating intimate contact between the DNAPL and the zero-valent iron (ZVI) particles. The EZVI is composed of food-grade surfactant, biodegradable oil, water, and ZVI particles (either nano- or micro-scale iron, nZVI, or mZVI), which form emulsion particles. The ZVI provides rapid abiotic degradation of the DNAPL constituents, and the oil provides an immediate sequestration of the DNAPL constituents as well as a long-term electron donor source to enhance further biodegradation. This report summarizes the work conducted to demonstrate/validate the EZVI technology at Parris Island Marine Corps Recruit Depot (MCRD) in South Carolina.