Bacteriophage Adsorption during Transport through Porous Media: Chemical Perturbations and Reversibility

In a series of seven column experiments, attachment of the bacteriophage PRD-1 and MS-2 to silica beads at pH’s 5.0–5.5 was at least partially reversible; however, release of attached phage was slow and breakthrough curves exhibited significant tailing. Rate coefficients for attachment and detachment were on the order of 10⁻⁴ and 10⁻⁶–10⁻⁴ s⁻¹, respectively. Corresponding time scales were hours for attachment and days for detachment. The sticking efficiency (α) for phage attachment was near 0.01. The rate of phage release was enhanced by raising pH and introducing surface-active chemical species, illustrating the importance of chemical perturbations in promoting biocolloid transport. In a series of batch experiments, MS-2 adsorbed strongly to a hydrophobic surface, octadecyltrichlorosilane-bonded silica, at both pH’s 5 and 7. Adsorption to the unbonded silica at pH 5 was linear, but was 2.5 (with Ca²⁺) to 0.25% (without Ca²⁺) of that to the bonded surface. Neither MS-2 nor PRD-1 adsorbed to unbonded silica at pH 7. Hydrophobic effects appear to be important for adsorption of even relatively hydrophilic biocolloids.