Model-based interpretation of low-temperature Aquifer Thermal Energy Storage combined with in situ bioremediation in a chlorinated ethene plume

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Description

Biodegradation can be an important mass removal process for organic pollutants in the subsurface. It is affected by the aquifer temperature, which directly influences microbial degradation rates. This study explores the effects of combining low-temperature aquifer thermal energy storage with in situ bioremediation (ATES-ISB) in a dissolved chlorinated ethene plume. For this purpose, we integrated field data from a pilot-scale experiment in a comprehensive non-isothermal reactive transport model. We present monitoring data of a pilot test at a field site in Denmark, which involved the injection of heated groundwater in a sandy aquifer with a dipole setup consisting of a pair of injection and extraction wells and monitoring wells. The bioremediation at the site was stimulated and augmented by injecting lactate and specialized degraders (Dehalococcoides).

The observational data were quantitatively interpreted in a heterogeneous, vertically-averaged numerical model. The process-based model can represent the strongly interdependent processes and accounts for site-specific geometric characteristics, highly dynamic pumping, spatially variable physico-chemical properties, reactive transport, heat addition, microbial growth, and temperature-dependent biodegradation by injected and indigenous microbes. Model results demonstrate the enhancement of contaminant mass removal and more complete reductive dechlorination by the combination of ATES and ISB. The calibrated model was used further to investigate realistic remediation scenarios considering different hydraulic and thermal operational conditions. The model can be applied to design, interpret, and optimize ATES-ISB systems and provides detailed insights into non-isothermal biodegradation in subsurface environments.
Period2 Oct 2024
Event titleThe Conference on Computational Methods in Water Resources: CMWR 2024
Event typeConference
Conference number25
LocationTucson, United States, ArizonaShow on map
Degree of RecognitionInternational