Hamaker constant effects on bacterial deposition in porous media

Bacterial transport is the critical initial step for biofilm formation and microbial functions in porous media. Various physicochemical properties determine the interaction between bacterial cells and matrix. There is, hence, interest to evaluate the Hamaker constant as a comprehensive indicator to quickly predict bacterial deposition in porous media. In this study, percolation column experiments were conducted using four model bacterial strains with distinct hydrophobicity and surface charge properties. Deposition efficiencies were quantified using clean-bed filtration theory and interpreted based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) interaction energy. Research found that hydrophobicity determines the surface energy and, hence, varies the Hamaker constant, posing significant effects on the XDLVO energy to dominant deposition efficiency. The positive correlation between the Hamaker constant and deposition efficiency was mechanistically explained by variations of the XDLVO interaction energy at the secondary minimum distance, which governs reversible deposition. This correlation was validated at both the initial and final stages of bacterial deposition in porous media. These findings indicate that the Hamaker constant provides a simplified yet effective theoretical tool for the prediction of bacterial transport.