Microbial Deposition in Porous Media: A Surface Thermodynamic Investigation

Abstract

A microbial transport study of Bacillus subtilis, Echerichia coli, Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida, and Pseudomonas sp. through a model medium of silica gel demonstrated that bacterial deposition in porous media was determined by interfacial interactions between bacteria and the medium as well as interfacial interactions between deposited and suspended bacterial cells. The clean bed collision efficiency, α₀ was an exponential function of ΔG₁₃₂^TOT (sum of ΔG₁₃₂^LW, free energy of van der Waals interactions and ΔG₁₃₂^AB, free energy of Lewis acid/base interactions between bacteria, and the medium matrix at the equilibrium distance). The blocking factor, B, that depicts the ratio of the blocked area to the geometric area of the medium surface, was an exponential function of ΔG₁₃₁^TOT (sum of ΔG₁₃₁^LW, free energy of van der Waals interactions and ΔG₁₃₁^AB, free energy of Lewis acid/base interactions between deposited and suspended bacterial cells at the equilibrium distance). Among the bacterial strains studied, P. aeruginosa had the greatest α₀ (0.151) and the greatest B (606.5) because P. aeruginosa had the smallest ΔG₁₃₂^TOT (-11.6 kT) the greatest ΔG₁₃₁^TOT (16.0 kT).