Inactivation of Cryptosporidium parvum oocysts with ozone and monochloramine at low temperature

Amy M. Driedger, Jason L. Rennecker, Benito J. Mariñas

Research output: Contribution to journalArticlepeer-review


The rate of Cryptosporidium parvum inactivation decreased with decreasing temperature (1-20°C) for ozone and for monochloramine applied alone as well as after pre-treatment with ozone. Synergy was observed at all temperatures studied for the ozone/monochloramine sequential disinfection scheme. The synergistic effect was found to increase with decreasing temperature. The inactivation rate with monochloramine after ozone pre-treatment was 5 times faster at 20°C and 22 times faster at 1°C than the corresponding post-lag phase rates of inactivation with monochloramine at these temperatures when no ozone pre-treatment was applied. The CT required for achieving 2-logs of inactivation ranged from 11 400 mg min l-1 at 20°C to 64 600 mg min l-1 at 1°C when monochloramine was applied alone. In contrast, the CT required for an overall sequential inactivation of 2-logs ranged from 721 mg min l-1 at 20°C to 1350 mg min l-1 at 1°C when applying monochloramine after ozone pre-treatment. The presence of excess ammonia in the monochloramine solutions was not responsible for the synergy observed in ozone/monochloramine sequential disinfection. Copyright (C) 2000 Elsevier Science Ltd.

Original languageEnglish (US)
Pages (from-to)41-48
Number of pages8
JournalWater Research
Issue number1
StatePublished - Jan 2001


  • Ammonia
  • Cryptosporidium parvum oocysts
  • Inactivation kinetics
  • Modified in vitro excystation
  • Monochloramine
  • Ozone
  • Sequential disinfection
  • Synergy
  • Temperature dependence

ASJC Scopus subject areas

  • Water Science and Technology
  • Ecological Modeling
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering
  • Civil and Structural Engineering


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