Environmental Molecular Sciences Laboratory

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Transport and Retention of Motile Microbes in Pore-Networks

Date: 
Monday, January 27, 2020
Principal Investigator: 
Rishi Parashar
Lead Institution: 
Desert Research Institute
Closed Date: 
Saturday, March 28, 2020
Project ID: 
51218
Abstract: 

Remediation of metal and radionuclide contaminants in soil and groundwater systems is challenging because of their strong chemical interactions with mineral surfaces and low concentration limits for human health requirements. In situ bioremediation is an attractive alternative to conventional methods; by stimulating the activity of natural microorganisms it is possible to manipulate the redox state of contaminants and greatly decrease their solubility, rendering them immobile and therefore reducing the risk of human exposure. Accurate numerical models of bioremediation are needed to support design and evaluation of field implementations. Existing models of contaminant bioremediation do not account for the movement of microorganisms, either passive movement with flowing groundwater or active movement by motile bacteria. We hypothesize that inclusion of microbial motility characteristics into a model of bacterial transport will significantly impact model predictions of metal bioremediation. A series of experiments with motile bacteria, using microfluidic devices and advance imaging techniques, will be conducted to quantify the fundamental character of bacterial motion in porous media during active swimming. The experiments will form the basis for development and testing of new models of microbial transport and retention. While motility (a cell-scale phenomenon) cannot be explicitly included in field-scale models, effective transport and attachment/detachment rates can be. Micro-scale experimental observations and the models developed will be included in pore-scale simulations that will be used to generalize and upscale microbial transport to a broader range of pore geometries and flow conditions. The results of pore-scale simulations will be used to parameterize effective transport and retention properties for field-scale models of microbial transport that can be incorporated into existing simulators of metal bioremediation. The enhanced models will support improved evaluation and design of future bioremediation implementations, thereby promoting better solutions to contamination problems and reducing risk of exposure to human and environmental receptors.