title: Quantification of pathogen inactivation efficacy by free chlorine disinfection of drinking water for QMRA.
abstract: To support the implementation of quantitative microbial risk assessment (QMRA) for managing infectious risks associated with drinking water systems, a simple modeling approach for quantifying Log10 reduction across a free chlorine disinfection contactor was developed. The study was undertaken in three stages: firstly, review of the laboratory studies published in the literature; secondly, development of a conceptual approach to apply the laboratory studies to full-scale conditions; and finally implementation of the calculations for a hypothetical case study system. The developed model explicitly accounted for variability in residence time and pathogen specific chlorine sensitivity. Survival functions were constructed for a range of pathogens relying on the upper bound of the reported data transformed to a common metric. The application of the model within a hypothetical case study demonstrated the importance of accounting for variable residence time in QMRA. While the overall Log10 reduction may appear high, small parcels of water with short residence time can compromise the overall performance of the barrier. While theoretically simple, the approach presented is of great value for undertaking an initial assessment of a full-scale disinfection contactor based on limited site-specific information.
authors: Water & Health Pty Ltd, P.O. Box 648, Salamander Bay 2317, Australia and Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway E-mail: s.petterson@waterandhealth.com.au.
authors: S R
authors: SR
authors: Petterson
authors: Durban University of Technology, SARChi Chair, Institute for Water and Wastewater Technology, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa.
authors: T A
authors: TA
authors: Stenström
mesh_terms: D058491:Bacterial Load / Q000187:drug effects; D002713:Chlorine / Q000494:pharmacology / Q000627:therapeutic use; D004203:Disinfection / Q000379:methods*; D060766:Drinking Water / Q000382:microbiology*; D018570:Risk Assessment; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D002713:Chlorine