HR: 1340h
AN: H23A-1412    [Abstracts]
TI: Lab-scale Investigation of Degradation Product Partitioning in Source Zones Containing Chlorinated Solvents
AU: * Ramsburg, C A
EM: andrew.ramsburg@tufts.edu
AF: Tufts University, Department of Civil and Environmental Engineering 200 College Ave. Room 113 Anderson Hall, Medford, MA 02155
AU: Christ, J A
EM: john.christ@usafa.af.mil
AF: US Air Force Academy, Department of the Air Force HQ USAFA/DFCE 2354 Fairchild Drive Suite 6J-159 , USAF Academy, CO 80840-6236
AU: Abriola, L M
EM: linda.abriola@tufts.edu
AF: Tufts University, Department of Civil and Environmental Engineering 200 College Ave. Room 113 Anderson Hall, Medford, MA 02155
AB: Recent trends in source-zone remediation technology development and implementation suggest in situ transformation or destruction mechanisms are becoming increasingly attractive relative to recovery mechanisms for treatment of dense nonaqueous phase liquids (DNAPLs). Processes such as bioaugmentation and the injection of zero valent iron rely upon the reductive dechlorination to transform tetrachloroethene (PCE) and trichloroethene (TCE) emanating from entrapped or pooled DNAPL. These processes typically produce a suite of degradation products which may include cis-dichloroethene (cis-DCE). When production of these degradation products is slow relative to DNAPL mass reduction there is potential for significant redistribution among all phases present in the source zone (solid, aqueous, and DNAPL). While several studies have examined mass transfer in DNAPL source zones, nearly all have focused on dissolution or solubilization processes (i.e., exchange from the organic phase). In situ production of degradation product species in the aqueous phase, however, requires that conceptual models of mass transfer consider both the exchange to and from the organic phase. This study investigates the partitioning of cis-DCE from the aqueous phase into a PCE-DNAPL in an abiotic source zone. Liquid-liquid equilibrium experiments were employed to determine the distribution of cis-DCE between the aqueous and organic phases. One-dimensional column experiments were conducted to elucidate partitioning kinetics under conditions of flow through a DNAPL source zone. Results indicate that the equilibrium distribution of cis-DCE favors the organic phase, creating a significant capacity for retention of degradation products. While retention in flowing systems was reduced by mass transfer limitations, these results may have significant implications for calculation of dissolution enhancement factors during source zone treatment. Current efforts are focused on incorporating partitioning kinetics into a compositional, multiphase model capable of simulating the metabolic reductive dechlorination process in heterogeneous DNAPL source zones.
DE: 0418 Bioremediation
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: Fall Meeting 2005