Objective:
Emulsified Zero-Valent Iron (EZVI) shows significant promise as a cost-effective remediation technology capable of expediting dense non-aqueous phase liquid (DNAPL) source zone remediation and groundwater cleanup. The objectives of this project include: (1) using laboratory microcosms as initial treatability study setups, evaluate the proportion of the chlorinated solvent mass destruction that is occurring due to abiotic dehalogenation versus enhanced biodegradation as a result of the addition of electron donor in the form of an oil emulsion; (2) inject EZVI into two pilot test areas within a DNAPL source zone using the two most promising EZVI injection technologies to evaluate the ability of EZVI to reduce significantly the mass flux of dissolved phase volatile organic compounds (VOC) from DNAPL source zones and to reduce the DNAPL mass in the source; and (3) provide reliable technical data relevant to field-scale EZVI trials, including documentation of the benefits of the technology in terms of expected reduction in the duration and cost of remediation of DNAPL sites. Technology Description: EZVI can be used to enhance the destruction of chlorinated solvent DNAPL in source zones by creating intimate contact between the DNAPL and the nano-scale ZVI. The EZVI is composed of food-grade surfactant, biodegradable vegetable oil, water, and ZVI particles (either nano- or micro-scale iron), which form emulsion particles that contain the ZVI in water surrounded by an oil-liquid membrane. Since the exterior oil membrane has hydrophobic properties similar to that of DNAPL, the emulsion is miscible with the DNAPL. Encapsulating the ZVI in a hydrophobic membrane protects the nano-scale iron from other groundwater constituents that would otherwise exhaust much of the reducing capacity of the nano-scale iron. This reduces the mass of EZVI required for treatment relative to unprotected ZVI. Until the oil membrane is consumed by biological activity, EZVI will combine directly with the target contaminants. In addition to the abiotic degradation associated with the ZVI, the injection of EZVI will result in enhanced biodegradation of dissolved chlorinated ethenes because the vegetable oil and surfactant act as electron donors to promote anaerobic biodegradation processes. Expected Benefits: Current approaches for remediation of DNAPL source areas are either inefficient and slow (e.g., pump and treat) or costly (e.g., thermal treatment). The relatively low injection costs and long-term residual remediation activity indicate that EZVI can result in significant operational lifetime cost savings. EZVI can rapidly remove DNAPL mass, but the benefits of this technology diminish at sites where less DNAPL is present and conventional ZVI or other technologies may be more appropriate. The EZVI technology combines the rapid abiotic degradation promoted by ZVI with slower biological degradation processes, realizing the strengths of each technology while reducing their individual limitations.
(Anticipated Project Completion - 2007) Principal Investigator: Mr. Thomas Krug Geosyntec Consultants, Inc. 130 Research Lane, Suite 2 Guelph, Ontario N1G 5G3 Telephone: (519) 822-2230 Fax: (519) 822-3151 E-mail: tkrug@geosyntec.com DoD Liaison: Dr. Nancy Ruiz Naval Facilities Engineering Service Center 1100 23rd Avenue, Code 411 Port Hueneme, CA 93043 Telephone: (805) 982-1155 Fax: (805) 982-4304 E-mail: nancy.ruiz@navy.mil | 
