Removal and Transport of Adenovirus 41 and φX174 in Saturated Goethite-Coated Sand Column.

In the present study, we examined the transport and retention behavior of a human pathogenic virus (Adenovirus 41, or Ad-41) and a model bacteriophage (ΦX174) in goethite-coated sand under saturated flow conditions using laboratory columns. Two sets of column transport experiments were conducted: with Ad-41 and ΦX174 individually or with the two viruses mixed together in the influent. All the experiments were conducted at pH 7.5 using 0.002 M artificial ground water buffer as background solution.   Results from these experiments show that the two viruses have different retention and transport behavior and that there is competition for the evidently limited numbers of retention sites when they were mixed in the influent. More ΦX174 was retained (99.5%) than Ad-41 (79.6 %) on goethite-coated sand in the first set of experiments but greater retention of Ad-41 than ΦX174 was observed in the second set of column experiments.  Mass recovery using 3% beef extract solution (pH 9.5) revealed that the removal of ΦX174 was reversible whereas the removal of Ad-41 was irreversible or inactivation. These differences are attributed to the different morphological and surface properties of the two viruses. Force measurements by atomic force microscopy show that the average adhesion force between virus and goethite-coated sand was lower for Ad-41 than ΦX174. In addition, the interaction forces measured between Ad-41 and goethite-coated sand varied at different locations, a clear indication that multiple forces are involved as a result of the complex structure and heterogeneous surface charge distribution of the virus.  Confocal laser scanning microscopy further confirmed the binding of the viruses on goethite-coated sand. The zeta potentials of both viruses and goethite-coated sand were measured and used for calculating Derjaguin–Landau–Verwey–Overbeek (DLVO) potential energy profiles.