title: On the cause of the tailing phenomenon during virus disinfection by chlorine dioxide.
abstract: This study investigates the mechanisms underlying the deviation from Chick-Watson kinetics, namely a tailing curve, during the disinfection of viruses by chlorine dioxide (ClO2). Tailing has been previously reported, but is typically attributed to the decay in disinfectant concentration. Herein, it is shown that tailing occurs even at constant ClO2 concentrations. Four working hypothesis to explain the cause of tailing were tested, specifically changes in the solution's disinfecting capacity, aggregation of viruses, resistant virus subpopulations, and changes in the virus properties during disinfection. In experiments using MS2 as a model virus, it was possible to rule out the solution's disinfecting capacity, virus aggregation and the resistant subpopulation as reasons for tailing. Instead, the cause for tailing is the deposition of an adduct onto the virus capsid over the course of the experiment, which protects the viruses. This adduct could easily be removed by washing, which restored the susceptibility of the viruses to ClO2. This finding highlights an important shortcoming of ClO2, namely its self-limiting effect on virus disinfection. It is important to take this effect into account in treatment applications to ensure that the water is sufficiently disinfected before human consumption.
authors.affiliation: Laboratory of Environmental Chemistry, School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Thérèse
authors.initials: T
authors.lastname: Sigstam
authors.forename: Andreas
authors.initials: A
authors.lastname: Rohatschek
authors.forename: Qingxia
authors.initials: Q
authors.lastname: Zhong
authors.forename: Moritz
authors.initials: M
authors.lastname: Brennecke
authors.forename: Tamar
authors.initials: T
authors.lastname: Kohn
mesh_terms: D017606:Chlorine Compounds / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D010087:Oxides / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014780:Viruses / Q000187:drug effects*
chemical_list: D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide
keywords: Chlorine dioxide; MALDI; Resistant subpopulation; Reversible protection; Tailing; Viruses