Nonaqueous phase liquid (NAPL) contaminants are difficult to remove from groundwater due, in part, to the heterogeneous structure of soil. Chemotaxis toward the chemical pollutants, which bacteria degrade, provides a mechanism for bacteria to migrate to locations of high contamination, which may enhance the overall effectiveness of bioremediation. The chemotactic effect on bacterial abundance was studied within the low permeable NAPL-contaminated region in a microfluidic device with a structured pore network that mimics features of the natural contaminated groundwater system. Chemotactic bacteria migrated preferentially into the contaminated region, and accumulated near NAPL ganglia; the observations were also supported by computational simulations based on advection-dispersion type equations. Two key parameters in the mathematical model were the chemotactic sensitivity coefficient and the chemotactic receptor constant. Other microfluidic devices were designed to create well-controlled concentration gradients in order to obtain reliable values of these parameters. A ratchet structure is used to enhance the signal of bacterial concentration for optical detection.

Chemotaxis of pollutant-degrading bacteria to toluene droplets retained within the low permeable region in a heterogeneous porous microfluidic device

244th National Meeting (2012)

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