Synergism in sequential disinfection of Cryptosporidium parvum

J. L. Rennecker, B. Corona-Vasquez, A. M. Driedger, B. J. Marinas

Research output: Contribution to journalConference articlepeer-review


Sequential treatment schemes using ozone or chlorine dioxide as primary disinfectant and free chlorine or monochloramine as secondary disinfectant were investigated for potential synergistic effects in the inactivation of C. parvum oocysts. Viability was determined by a modified in vitro technique based on sporozoite counts that was consistent with animal infectivity data. Primary disinfection with ozone resulted in the disappearance of a predominant shoulder in the secondary inactivation curve for both free and combined chlorine. The rate of secondary inactivation with monochloramine increased by approximately 250 percent compared to the post-shoulder rate with monochloramine alone. The level of synergy from using chlorine dioxide as the primary disinfectant was lower compared to that for ozone.

Original languageEnglish (US)
Pages (from-to)47-52
Number of pages6
JournalWater Science and Technology
Issue number7
StatePublished - 2000
EventThe 1999 International Conferecne on 'Minimising Risk from Cryptosporidium and other Waterborne Particles' - Paris, Fr
Duration: Apr 19 1999Apr 23 1999


  • Chloramine
  • Chlorine dioxide
  • Cryptosporidium parvum
  • Free chlorine
  • Ozone
  • Sequential disinfection

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology

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