CAREER: Multiscale Bacterial Transport in Porous Media

Controlling bacterial transport in soils could help prevent the spread of pathogens in groundwater, contribute to sustainable agriculture by acting on the soil microbiome, and help clean up environmental pollutants. However, existing knowledge of the interactions between the bacteria and the surrounding fluids and surfaces is insufficient to explain their transport even in simple confining structures. This award will bridge existing limitations by quantifying bacterial transport from microscopic pores to distances in the scale of meters and modeling their motion by accounting for the interactions between the bacteria and the complex flow landscape. The research will inform our future ability to predict and tune bacterial transport by engineering porous media and controlling water flow. The project includes an integrated education program using the topics of microscopes, soil microbiome, and water to increase representation in STEM and educate graduate students for success. The plan will bring hands-on activities and public science talks to cultivate interest in science in families. These activities will be offered in English and Spanish in schools and public places in underserved communities. To create a quantitative understanding to predict and control the transport of bacteria in soils, this project will experimentally and computationally explore how particle and pore-scale physical interactions, bacterial activity, and chemical gradients affect the transport of swimming bacteria across scales in porous media. The project will: (1) quantify for the first time fundamental magnitudes of transport, like the distances and times covered by bacteria upstream and downstream across scales in simple geometries, using unique equipment built for this purpose; (2) develop a computational description that accounts for the solvent’s fluctuating velocity field under high confinement; and (3) quantify and model the transport across scales in complex porous media as a function of the flow, statistical properties of the medium, and the effect of chemoattractants. Results from this research can contribute to designing and optimizing biofiltration systems for pollution control and wastewater treatment, and it could inform new ways of separating bacteria, impacting industries like biotechnology, pharmaceuticals, and biofuels. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.