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Communication Dans Un Congrès Année : 2022

Dispersion of motile bacteria in a porous medium: Experimental data and theory

Résumé

The sound understanding and quantification of the transport and dispersion mechanisms of bacteria in porous media is of central concern in applications such as bioremediation and biomineralization. Recent experimental and numerical studies indicate that motility plays a key role for the fate of bacteria. Data from microfluidic experiments in model porous media consisting of randomly placed pillars show that non-motile bacteria have compact displacement distributions, while the distribution of motile bacteria are characterized by strong peak retention and forward tailing. Detailed analysis of bacteria trajectories reveals two key attributes: 1. The emergence of a motility-induced trapping and retention process due to active motion from the stream toward the solid grain. 2. Increase or decrease of dispersion due to the transfer between pore channels and grains, depending on the flow rate. We develop a physical model based ona continuous time random walk (CTRW) approach. Bacteria dispersion due to hydrodynamic flow fluctuations is quantified by a Markov model for the equidistantly sampled particle speeds. The impact of motility is modeled by a two-rate trapping process that accounts for the motion toward and active trapping at the grains. The theoretical model captures the displacement distributions of both non-motile and motile bacteria. It provides explicit analytical expressions for the motility-induced hydrodynamic dispersion coefficients in terms of the trapping and release rates, which characterize the bacteria motility. The experimental data shows that these motility parameters are flow-rate dependent, which manifest in a reduction of dispersion compared to the non-motile bacteria at low flow rates, and an increase at high flow rates. The model reproduces the experimental observations and allows to predict bacteria dispersion at the continuum scale. How to cite: Dentz, M., Creppy, A., Douarche, C., Clément, E., and Auradou, H.: Dispersion of motile bacteria in a porous medium: Experimental data and theory, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7580, https://doi.org/10.5194/egusphere-egu22-7580, 2022.
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Dates et versions

hal-04438783 , version 1 (05-02-2024)

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Marco Dentz, Adama Creppy, Carine Douarche, Eric Clément, Harold Auradou. Dispersion of motile bacteria in a porous medium: Experimental data and theory. EGU General Assembly, May 2022, Vienne (AUT), Austria. ⟨10.5194/egusphere-egu22-7580⟩. ⟨hal-04438783⟩
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