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Emulsified Zero-Valent Iron
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The Technology
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Thousands of sites across the United States have been identified that are contaminated with dense non-aqueous phase liquids (DNAPLs). However, few technologies exist that can treat DNAPLs in a timely and cost-effective manner. For example, traditional pump-and-treat methods can require decades of treatment time and operational costs. Other methods that treat DNAPLs in place, such as steam injection and radio-frequency-heating, are expensive and can cause contaminant mobilization. NASA's Emulsified Zero-Valent Iron (EZVI) technology overcomes these limitations by providing a method that is quick, effective, and cost-competitive.
| How It Works |  |
EZVI involves placing nanoscale zero-valent iron particles into a surfactant-stabilized, biodegradable water-in-oil emulsion. This emulsion is injected into the DNAPL-contaminated zones of the subsurface. The DNAPL is then pulled into the emulsion where the contaminant reacts with the zero-valent iron. Through a process known as reductive dehalogenation, the DNAPL and its daughter products are degraded into ethane and other hydrocarbons. These by-products are finally broken down through biological activities in the subsurface.
| Benefits | |
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Directly treats contaminant source: Numerous methods are available for treating dissolved phase contaminants, but EZVI is one of the few technologies that can effectively treat the DNAPL source. |
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Does not mobilize contaminants: Many DNAPL treatment methods can mobilize DNAPLs to previously uncontaminated areas. In contrast, EZVI treats contaminants in place with no mobilization. |
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Requires less treatment time: Although traditional pump-and-treat systems can require decades of operation for complete DNAPL removal, remediation with EZVI takes only 2-3 months. |
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Is cost-competitive: Treatment costs using EZVI are competitive with alternative methods such as pump-and-treat, thermal treatment, and in-situ chemical oxidation. |
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Produces less toxic and more easily degradable by-products: Other technologies can generate chlorinated daughter products that can be harmful to the environment. In contrast, EZVI produces small quantities of hydrocarbons, such as ethene, that are relatively nontoxic and naturally degraded. |
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Is environmentally safe: EZVI is made from environmentally friendly and biodegradable materials. |
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Is effective in oxidative or saline environments: Unlike other reductive technologies, EZVI is capable of working in sites with high dissolved oxygen or saline conditions. The oil membrane around the iron particles protects the metal from competing reactions. |
| Commercial Uses | |
Thousands of sites across the United States face problems with DNAPL contamination. The EPA has reported that DNAPLs are present at 60% to 70% of all sites on the Superfund National Priorities List. Emulsified Zero-Valent Iron is a versatile technology that can be used at many of these locations.
Applicable sites may include:
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Dye and paint manufacturers |
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Dry cleaners |
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Chemical manufacturers |
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Metal cleaning and degreasing facilities |
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Leather tanning facilities |
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Pharmaceutical manufacturers |
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Adhesive and aerosol manufacturers |
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Government facilities |
| Success | |
Researchers at NASA and the University of Central Florida originally developed EZVI as an innovative method for treating chlorinated solvents at Kennedy Space Center's Launch Complex 34. During the 1960s, chlorinated solvents, including TCE, were used at this site to clean rocket engines. As a result, groundwater became contaminated with DNAPLs.
EZVI was field-tested at Launch Complex 34 under the U.S. EPA SITE Program. Based on the success of this deployment, NASA licensed EZVI to seven companies that are producing their own versions of the technology. These companies have used the technology to treat TCE and PCE in multiple states, including Arkansas, Florida, North Carolina, and Tennessee. Click here for a list of technology providers.
In 2006, EZVI was selected as a winner of the Award for Excellence in Technology Transfer by the Federal Laboratory Consortium. This annual award is given to researchers who have exhibited outstanding performance in the transfer of a technology from a federal laboratory to the commercial market.
Click here for information on EZVI laboratory studies conducted at the University of Central Florida (UCF).
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