Application of emulsified zero-valent iron: Four full-scale remediation sites

Emulsified zero‐valent iron (EZVI) is a technology developed by the National Aeronautics and Space Administration (NASA) that is used to remediate soil and groundwater contaminated with chlorinated solvents. It consists of micro‐ and/or nano‐scale iron particles suspended in a water‐in‐vegetable oil emulsion. This allows EZVI to combine three remediation technologies: partitioning of the chlorinated volatile organic compounds (CVOCs) into vegetable oil, a chemical reaction between the CVOCs and elemental iron, and hydrogen production from the fermentation of the vegetable oil to promote biological degradation. A description of the chemistry and biology of this NASA technology is presented, followed by a description of four full‐scale case studies where EZVI has been applied, including post‐injection results extending over three years. At each of these sites, EZVI was determined to be the most cost‐effective remedy. The sustained treatment long after the injections resulted in contaminant reductions continuing for over three years and accelerated remediation times compared to traditional approaches, due to the combination of technologies. Furthermore, EZVI is consistent with US EPA's green remediation policy. © 2011 Wiley Periodicals, Inc.