Relative transport of human adenovirus and MS2 in porous media

Human adenovirus (HAdV) is the most prevalent enteric virus found in the water environment by numerous monitoring studies and MS2 is the most common surrogate used for previous virus transport studies. However, the current knowledge on the transport behavior of HAdV in porous media and the transport relationship between HAdV and MS2 is very limited. In this study, we investigated the influence of ionic strength (IS) on the transport behaviors of HAdV, MS2, and pilus-associated MS2 (p-MS2) in saturated quartz sand columns. Retention of HAdV was higher than MS2 in all three IS (1, 10 and 100mM NaCl), especially in 10 and 100mM where virus recoveries in the effluent samples were ≤1% for HAdV, but ≥55% for MS2. Derjaguin and Landau, Verwey and Overbeek (DLVO) theory alone cannot explain why the deposition of HAdV was so much higher. HAdV retention may be strongly enhanced by attaching its long fibers to the sand surface and this deposition mechanism is supported by DLVO energy profiles which show that HAdV can approach the sand surface within reach of its fibers at 10 and 100mM NaCl. Results of transmission electron microscopy, dynamic light scattering and 0.05μm membrane filtration suggest that the majority of MS2 cultured by Escherichia coli Famp were associated with a residue of pili. Although retention of pilus-associated MS2 (p-MS2) in the column was just slightly higher than individual MS2 particles, membrane filtration results indicated potentially important differences between removal of MS2 and p-MS2 by filtration with finer pore sizes. This is the first study reporting (1) increasing differences in the transport of HAdV and MS2 in porous media with an increase in ionic strength; (2) significant influence of pilus-association to MS2 removal by membrane and porous media filtration; and (3) a mechanistic explanation for the deposition differences of HAdV and MS2 using virus morphology information and DLVO theory.