title: Inactivation of F-specific bacteriophages during flocculation with polyaluminum chloride - a mechanistic study.
abstract: Bacteriophages are often used as surrogates for enteric viruses in spiking experiments to determine the efficiencies of virus removal of certain water treatment measures, like e.g. flocculation or filtration steps. Such spiking experiments with bacteriophages are indispensable if the natural virus concentrations in the raw water of water treatment plants are too low to allow the determination of elimination levels over several orders of magnitude. In order to obtain reliable results from such spiking tests, it is essential that bacteriophages behave comparable to viruses and remain stable during the experiments. To test this, the influence of flocculation parameters on the bacteriophages MS2, Qβ and phiX174 was examined. Notably, the F-specific phages MS2 and Qβ were found to be inactivated in flocculation processes with polyaluminum chloride (PACl). In contrast, other aluminum coagulants like AlCl3 or Al2(SO4)3 did not show a comparable effect on MS2 in this study. In experiments testing the influence of different PACl species on MS2 and Qβ inactivation during flocculation, it could be shown that cationic dissolved PACl species (Al13) interacted with the MS2 surface and hereby reduced the surviving phage fraction to c/c0 values below 1*10(-4) even at very low PACl concentrations of 7 μmol Al/L. Other inactivation mechanisms like the irreversible adsorption of phages to the floc structure or the damage of phage surfaces due to entrapment into the floc during coagulation and floc formation do not seem to contribute to the low surviving fraction found for both F-specific bacteriophages. Furthermore, no influence of phage agglomeration or pH drops during the flocculation process on phage inactivation could be observed. The somatic coliphage phiX174 in contrast did not show sensitivity to chemical stress and in accordance only slight interaction between Al13 and the phage surface was observed. Consequently, F-specific phages like MS2 should not be used as surrogate for viruses in flocculation experiments with PACl to determine the removal rates of viruses, as the results are influenced by a strong inactivation of the bacteriophages due to the experimental conditions.
authors.affiliation: DVGW-Technologiezentrum Wasser (TZW), Karlsruher Str. 84, D-76139 Karlsruhe, Germany. Electronic address: katja.kreissel@siemens.com.
authors.forename: Katja
authors.initials: K
authors.lastname: Kreißel
authors.affiliation: DVGW-Technologiezentrum Wasser (TZW), Karlsruher Str. 84, D-76139 Karlsruhe, Germany. Electronic address: monika.boesl@tzw.de.
authors.forename: Monika
authors.initials: M
authors.lastname: Bösl
authors.affiliation: DVGW-Technologiezentrum Wasser (TZW), Karlsruher Str. 84, D-76139 Karlsruhe, Germany. Electronic address: michael.huegler@tzw.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Hügler
authors.affiliation: DVGW-Technologiezentrum Wasser (TZW), Karlsruher Str. 84, D-76139 Karlsruhe, Germany. Electronic address: pia.lipp@tzw.de.
authors.forename: Pia
authors.initials: P
authors.lastname: Lipp
authors.affiliation: Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Karlsruhe, Germany. Electronic address: matthias.franzreb@kit.edu.
authors.forename: Matthias
authors.initials: M
authors.lastname: Franzreb
authors.affiliation: DVGW-Technologiezentrum Wasser (TZW), Karlsruher Str. 84, D-76139 Karlsruhe, Germany. Electronic address: beate.hambsch@tzw.de.
authors.forename: Beate
authors.initials: B
authors.lastname: Hambsch
mesh_terms: D017908:Allolevivirus / Q000187:drug effects / Q000378:metabolism*; D000536:Aluminum Hydroxide / Q000494:pharmacology*; D060766:Drinking Water / Q000592:standards* / Q000821:virology; D024202:Electrophoretic Mobility Shift Assay; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D017909:Levivirus / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D014764:Viral Proteins / Q000378:metabolism; D038301:Virus Inactivation / Q000187:drug effects*; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D014764:Viral Proteins; C096923:maturation protein, Enterobacterio phage MS2; C016213:aluminum oxychloride; D000536:Aluminum Hydroxide
keywords: Coagulation; Inactivation; MS2; Polyaluminum chloride; phiX174