Bacterial deposition in porous medium as impacted by solution chemistry

Bacterial transport in porous medium was investigated by means of column experiments using typical rod-shaped bacteria of Escherichia coli and Pseudomonas fluorescens. Mobility of E. coli and P. fluorescens in silica gel decreased with increasing ionic strength of the solution. In the presence of nonionic surfactants, the mobility of E. coli and P. fluorescens increased, and this was more pronounced at lower than at higher ionic strength. Bacterial transport in the porous medium was described by the equilibrium-kinetic two-region model and bacterial deposition was assumed to occur in the kinetic adsorption region only. Quantified bacterial deposition from bacterial column breakthrough curves was related to electrostatic and Lifshitz-van der Waals interactions between bacterial cells and medium surfaces. It was found that electrostatic interactions played a more important role than Lifshitz-van der Waals interactions in determining bacterial deposition in the porous medium, and were actually the barrier for bacteria to attach to the porous medium.