title: Indigenous bacterial spores as indicators of Cryptosporidium inactivation using chlorine dioxide.
abstract: This objective of this study was to explore the practicality of monitoring naturally occurring organisms to predict drinking water treatment plant performance, in this case for the reduction of Cryptosporidium. Surface and ground water from seven drinking water treatment plants across North America that use chlorine dioxide were surveyed for aerobic and anaerobic bacterial spore concentrations. The concentrations of total spores were usually high enough in both raw and treated water to allow 4- to 5-log reductions to be observed across the treatment train by filtering up to 2 l of sample. These results suggested that naturally occurring treatment-resistant spores could be candidates as indicators of treatment performance. However, to be useful as indicators for Cryptosporidium reduction, the organisms would have to exhibit similar resistances to disinfection (chlorine dioxide in this case) in order to be useful. The inactivation kinetics of seven of the most common species were determined, and all were observed to be considerably more susceptible to chlorine dioxide inactivation than Cryptosporidium as reported in the literature. This study therefore did not identify an appropriate ambient microbial indicator for Cryptosporidium control.
authors.affiliation: Department of Civil Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sophie
authors.initials: S
authors.lastname: Verhille
authors.forename: Ron
authors.initials: R
authors.lastname: Hofmann
authors.forename: Christian
authors.initials: C
authors.lastname: Chauret
authors.forename: Robert
authors.initials: R
authors.lastname: Andrews
mesh_terms: D000818:Animals; D002170:Canada; D017606:Chlorine Compounds / Q000494:pharmacology*; D016785:Cryptosporidium parvum / Q000187:drug effects* / Q000254:growth & development; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D006801:Humans; D010087:Oxides / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects* / Q000254:growth & development; D013997:Time Factors; D014481:United States; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods* / Q000592:standards
chemical_list: D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide