Diffusion/dispersion-limited mixing and reactions in saturated homogeneous and heterogeneous porous media
Final Report Abstract
The working hypothesis that transient flow conditions and flow focusing in high-permeability inclusions determine mixing and reaction enhancement was investigated in a number of conservative and reactive experimental setups. The outcome of the work shows that mixing and reaction enhancements were caused by both transient flow fields and flow focusing. However, for both conservative and reactive tracers, the contribution of porous medium heterogeneity, in the form of geometrically well-defined high-permeability lenses was distinctly more significant. The results of this study demonstrate the importance of flow focusing, suggested in the theoretical work of Werth et al. (2006), for the development of dissolved plumes in groundwater. Forward conservative and reactive transport modeling showed a good agreement with the measured concentrations and the observed plumes behavior, and proved to be a useful tool for an improved interpretation of experimental results. Based on the outcome of the numerical simulations, a quantitative analysis of the different experiments was possible. Parameters such as the zeroth, first and second central moments, dilution index and reactor ratio were calculated for the conservative experiments, whereas, for the reactive experiments, the quantitative analysis was based on the computed masses and mass fluxes of the product of an instantaneous mixing-controlled reaction. The collaboration with TP5 led to the development of CCD imaging techniques that were demonstrated to provide, for most of the investigated setups, high-resolution data in agreement with conventional sampling at the outlet of the flow-through systems and with the outcome of numerical simulations. Finally, interesting outcomes were obtained from a series of multi-tracer experiments. In fact, it was demonstrated that, at least at the experimental bench-scale, transverse mechanical dispersion cannot be considered compound independent as assumed by the classical description of the process.
Publications
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(2007). Fringe-controlled biodegradation of a toluene/ethylbenzene plume in homogeneous and heterogeneous porous media: laboratory experiments and model-based interpretation. International Workshop on “Biogeochemical Processes in Groundwater Systems”, Munich, Germany, 10-11 September 2007
Rolle M., Bauer R.D., Campanelli R., Kolditz O., Bauer S., Meckenstock R.U., Griebler C.
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(2007). Numerical Modelling of Biodegradation Reactions and Redox Zonation in Contaminated Aquifers. RemTech, Remediation Technologies, Ferrara, Italy, 26-28 September 2007
Rolle M., Sethi R., Di Molfetta A., Bauer S., Kolditz O.
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(2007). “Lab-Scale Experiments and Numerical Modeling of Mixing and Degradation of Pollutants in Aquifers” AGU Fall Meeting, San Francisco, 10-14 December 2007
Grathwohl P., Rolle M., Eberhardt C., Bauer R., Meckenstock R.U., Griebler C.
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(2007). “Laboratory-scale evaluation of mixing enhancement through flow focusing in heterogeneous porous media”. International Workshop on “Biogeochemical Processes in Groundwater Systems”, Munich, Germany, 10-11 September 2007
Eberhardt C., Rolle M., Jäger S., Gauglitz G., Grathwohl P.
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(2008). Influence of flow focusing on transverse mixing in heterogeneous porous media: laboratory experiments and model-based interpretation. IAHS Red Book Series, 324, 348-355
Rolle M., Eberhardt C., Grathwohl P.
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(2008). Reactive transport of organic contaminants in groundwater: importance of mixing and biodegradation processes. Proceedings of the Africa Water Resource Management Conference, Edited by O. Totolo
Rolle M., Moreno R.M., Grathwohl P.
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(2008). “Aerobic degradation of a toluene plume in homogeneous and heterogeneous porous media”. IAHS Red Book Series, 324, 356-363
Rolle M., Bauer R.D., Griebler C., Meckenstock R.U., Bauer S., Kolditz O., Grathwohl P.
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(2008). “Determination of vertical transverse dispersion with multi-tracer laboratory experiments”. AGU Fall Meeting, San Francisco, 15-19 December 2008
Chiogna G., Eberhardt C., Rolle M., Grathwohl P.
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(2009). Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes. Journal of Contaminant Hydrology, 105, 56–68
Bauer, R.D., Rolle, M., Bauer, S., Eberhardt, C., Grathwohl, P., Kolditz, O., Meckenstock, R.U., Griebler, C.
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(2009). “ Experimental Investigation and Numerical Modeling of Mixing and Degradation of Pollutants in Aquifers”. Aquaterra Final Conference, Tübingen, 25-27 March 2009
Rolle M., Eberhardt C., Anneser B., Griebler C., Prommer H., Grathwohl P.
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(2009). “Experimental investigation and numerical modeling of diffusion/dispersion limited reactions in saturated porous media”. Workshop TRePro II, Karlsruhe, 15-17 March 2009
Rolle M., Eberhardt C., Chiogna G., Grathwohl P.
