Application of Reactive Transport Modeling to Quantify Enhanced Bioremediation and Removal of Chloroethenes from Groundwater
Abstract
The use of bioaugmentation to treat fractured rock aquifers contaminated with chloroethenes can potentially reduce the chloroethene mass in an aquifer and restore water quality. Simulating these processes may require information on the groundwater flow, transport, matrix diffusion, mixing and geochemical reaction rates that must be synthesized to quantify the efficacy of this treatment. Reactive transport modeling provides an approach to integrate these diverse observations and provide better understanding of the factors controlling the long-term fate of the chloroethenes. In this study, reactive transport modeling was used to synthesize and quantify these in situ processes in the fractured rock aquifer at the NAWC site located near Trenton New Jersey. The modeling approach accounted for mass transfer limited exchange of solutes between the fracture porosity and the rock matrix. The bioaugmentation experiment was conducted by injecting the dehalococcoides together with EOS™ into a packed-off fracture zone at a depth of approximately 30 meters. Groundwater samples were collected from the injection well and an observation well approximately 20 m down gradient for over four years providing a detailed time series of concentrations. Observed bromide concentrations were used to calibrate a including the mass transfer rates of bromide exchange with the fractured rock matrix. Good calibration results were obtained using the mass transfer model to describe the bromide interactions when the matrix exchange was represented. PHT3D was used to successfully simulate diffusion of the chloroethenes in the fractured rock aquifer. Overall the PHT3D simulations matched the observed solute concentrations at the injection and observation wells by using a simple modeling approach where solute in the matrix exchanges slowly with solutes in the bulk water.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H41I1802C
- Keywords:
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- 1832 Groundwater transport;
- HYDROLOGY;
- 1835 Hydrogeophysics;
- HYDROLOGY;
- 4303 Hydrological;
- NATURAL HAZARDS;
- 8010 Fractures and faults;
- STRUCTURAL GEOLOGY