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Emulsified zerovalent iron for treating source zone chlorinated solvents at a Superfund site over six years
Citation:
Su, C., R. Puls, T. Krug, M. Watling, S. O'Hara, J. Quinn, AND N. Ruiz. Emulsified zerovalent iron for treating source zone chlorinated solvents at a Superfund site over six years. 11th International Symposium on Environmental Geochemistry, Beijing, Peking University, CHINA, August 07 - 10, 2019.
Impact/Purpose:
It is important to develop and verify methods for groundwater remediation. Groundwater contamination by tetrachloroethene (PCE) occurred from a 1994 spill at the Marine Corps Recruit Depot (MCRD), Parris Island, South Carolina, Superfund site. Containment and treatment of the source zone was critical in controlling the migration of the contaminant plume. Emulsified zerovalent iron (EZVI) was injected into the treatment areas in October 2006, and performance monitoring was conducted until October 2012. The field demonstration consisted of two side-by-side treatment areas to evaluate the performance of EZVI to remediate a shallow (58%) and a significant increase in the mass flux of ethene (628%). There were significant reductions in total CVOC mass (78%); an estimated reduction of 23% in the sorbed and dissolved phases and 95% reduction in the PCE DNAPL mass. Significant increases in dissolved sulfide, volatile fatty acids (VFA), and total organic carbon (TOC) were observed and dissolved sulfate and pH decreased in many wells. The effective remediation seems to have been accomplished by a combination of abiotic dechlorination by nanoiron and biological reductive dechlorination stimulated by the oil in the emulsion. This study provides novel information about the long-term effect of EZVI injection on contaminant degradation and removal.
Description:
Groundwater contamination by tetrachloroethene (PCE) occurred from a 1994 spill at the Marine Corps Recruit Depot (MCRD), Parris Island, South Carolina, Superfund site. Containment and treatment of the source zone was critical in controlling the migration of the contaminant plume. Emulsified zerovalent iron (EZVI) was injected into the treatment areas in October 2006, and performance monitoring was conducted until October 2012. The field demonstration consisted of two side-by-side treatment areas to evaluate the performance of EZVI to remediate a shallow (58%) and a significant increase in the mass flux of ethene (628%). There were significant reductions in total CVOC mass (78%); an estimated reduction of 23% in the sorbed and dissolved phases and 95% reduction in the PCE DNAPL mass. Significant increases in dissolved sulfide, volatile fatty acids (VFA), and total organic carbon (TOC) were observed and dissolved sulfate and pH decreased in many wells. The effective remediation seems to have been accomplished by a combination of abiotic dechlorination by nanoiron and biological reductive dechlorination stimulated by the oil in the emulsion.