Escherichia coli transport in porous media: influence of cell strain, solution chemistry, and temperature.

Packed bed column and complementary characterization experiments were carried out with two Escherichia coli strains (D21 g and XL1-Blue) under a range of ionic strength (IS) and valence (KCl, CaCl(2), and artificial groundwater) to determine the role of bacterial strain and solution chemistry on cell adhesion. Increasing IS and valence had a marked effect on the electrokinetic and surface properties of bacteria and quartz grains; hence resulting in a greater rate of deposition. Distinct deposition trends were observed for the two cell strains, with greater retention observed for D21 g versus XL1-Blue across the range of IS. Selected transport and characterization experiments were also conducted with the D21 g cells, finding deposition also increasing with IS and valence. In the presence of Ca(2+) bacterial deposition behavior deviated from anticipated trends and it is concluded from additional analysis that Ca(2+) ions influence bacterial surface charge, hydrophobicity, and extracellular polymers. Further transport experiments were conducted with the D21 g cells and colloids to establish the role of temperature (4, 10 and 25 degrees C). Results suggested that a combination of specific and non-specific interactions occurring between the cells and quartz determines the extent of deposition, rather than transport from the bulk to the collector surface.