Contribution of extracellular polymeric substances on representative gram negative and gram positive bacterial deposition in porous media.

The significance of extracellular polymeric substances (EPS) on cell transport and retained bacteria profiles in packed porous media (quartz sand) was examined by direct comparison of the overall deposition kinetics and retained profiles of untreated bacteria (with EPS) versus those of treated cells (without EPS) from the same cell type. Four representative cell types, Pseudomonas sp. QG6 (gram-negative, motile), mutant Escherichia coli BL21 (gram-negative, nonmotile), Bacillus subtilis (gram-positive, motile), and Rhodococcus sp.

Hysteresis of colloid retention and release in saturated porous media during transients in solution chemistry.

Saturated packed column and micromodel transport studies were conducted to gain insight on mechanisms of colloid retention and release under unfavorable attachment conditions. The initial deposition of colloids in porous media was found to be a strongly coupled process that depended on solution chemistry and pore space geometry. During steady state chemical conditions, colloid deposition was not a readily reversible process, and micromodel photos indicated that colloids were immobilized in the presence of fluid drag.

Coupled factors influencing the transport and retention of Cryptosporidium parvum oocysts in saturated porous media.

The coupled role of solution ionic strength (IS), hydrodynamic force, and pore structure on the transport and retention of viable Cryptosporidium parvum oocyst was investigated via batch, packed-bed column, and micromodel systems. The experiments were conducted over a wide range of IS (0.1-100 mM), at two Darcy velocities (0.

Macromolecule mediated transport and retention of Escherichia coli O157:H7 in saturated porous media.

The role of extracellular macromolecules on Escherichia coli O157:H7 transport and retention was investigated in saturated porous media. To compare the relative transport and retention of E. coli cells that are macromolecule rich and deficient, macromolecules were partially cleaved using a proteolytic enzyme.

Surface characteristics and adhesion behavior of Escherichia coli O157:H7: role of extracellular macromolecules.

Experiments were conducted using enterohemorrhagic Escherichia coli O157:H7 cells to investigate the influence of extracellular macromolecules on cell surface properties and adhesion behavior to quartz sand. Partial removal of the extracellular macromolecules on cells by a proteolytic enzyme (proteinase K) was confirmed using Fourier transform infrared spectroscopy analyses. The proteinase K treated cells exhibited more negative electrophoretic mobility (EPM) at an ionic strength (IS) < or = 1 mM, a slightly lower isoelectric point, and were less hydrophobic as compared to the untreated cells.

Escherichia coil O157:H7 transport in saturated porous media: role of solution chemistry and surface macromolecules.

The transport and deposition behavior of Escherichia coli O157: H7 was investigated in saturated packed-bed columns and micromodel systems over a range of ionic strength (IS) (1, 10, and 100 mM) and pH (5.8, 8.4, and 9.

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.