Integrated Modeling and Experimental Evaluation of Hydrodynamic and Microbial Controls on DNAPL Dissolution and Detoxification
EMSL Project ID
40075
Abstract
Tetrachloroethene (PCE) and trichloroethene (TCE) are among the most common organic subsurface contaminants at DOE and many other contaminated sites. In situ bioremediation of aqueous-phase PCE and TCE is increasingly being applied at these sites and is generally based on dehalorespiration. In dehalorespiration, a chlorinated organic compound is used as the terminal electron acceptor by certain bacterial strains and concomitantly undergoes reductive dehalogenation. However, at many contaminated sites, PCE and TCE were released into the subsurface in the form of dense non-aqueous phase liquids (DNAPLs). Several hundred years may be required to deplete DNAPL source zones via abiotic dissolution under natural conditions. Thus DNAPLs often act as long-term sources of groundwater contamination and currently are a major impediment to successful implementation of bioremediation of PCE and TCE contamination. The proposed research focuses on improving our understanding of the factors controlling DNAPL dissolution rates in practice-information that is key to developing and implementing effective strategies for enhancing source zone clean-up and effective bioremediation of aqueous phase contaminants at DOE and other sites where DNAPLs are present. In particular, little is currently known about the ability of dehalorespiring bacterial strains to grow in DNAPL source zones and affect contaminant dissolution, because of the difficulties of characterizing their distribution in situ using conventional porous media columns and tanks. These limitations will be overcome in the proposed research using a unique experimental approach that applies fluorescent in situ hybridization (FISH) to quantify the growth of individual dehalorespiring populations near the DNAPL-water interface and in the dissolved contaminant plume within a pore-scale micromodel system. Specifically, the micromodel-FISH experiments will be integrated with mathematical modeling to determine how hydrodynamic conditions and competitive and other ecological interactions select for different dehalorespiring populations and quantify the effects on contaminant dissolution fluxes. The use of pore-scale micromodel facilities and collaborations with experts in the application of FISH and micromodels in subsurface biogeochemistry research at EMSL are critical to the success of the proposed work.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2010-10-01
End Date
2012-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Wesseldyke ES, JG Becker, EA Seagren, AS Mayer, and C Zhang. 2015. "Numerical Modeling Analysis of Hydrodynamic and Microbial Controls on DNAPL Pool Dissolution and Detoxification: Dehalorespirers in Co-culture." Advances in Water Resources 78:112–125. doi:10.1016/j.advwatres.2015.01.009