OxyFile #178

UI  - 94113739
AU  - Finch GR
AU  - Black EK
AU  - Gyurek L
AU  - Belosevic M
TI  - Ozone inactivation of Cryptosporidium parvum in demand-free
      phosphate buffer determined by in vitro excystation and animal
AD  - Department of Civil Engineering, University of Alberta, Edmonton,
AB  - Inactivation of Cryptosporidium parvum oocysts by ozone was
      performed in ozone demand-free 0.05 M phosphate buffer (pH 6.9)
      in bench-scale batch reactors at 7 and 22 degrees C. Ozone was
      added to each trial from a concentrated stock solution for
      contact times ranging from 5 to 15 min. The viability of the
      control and treated oocysts was determined by using in vitro
      excystation and infection in neonatal CD-1 mice. It was found
      that excystation consistently underestimated inactivation when
      compared with animal infectivity (P < or = 0.05). As
      inactivations increased, the difference between excystation and
      infectivity also increased. The inactivation kinetics of C.
      parvum by ozone deviated from the simple first-order Chick-Watson
      model and was better described by a nonlinear Hom model. The use
      of the Hom model for predicting inactivation resulted in a family
      of unique concentration and time values for each inactivation
      level rather than the simple CT product of the Chick-Watson
LA  - Eng
SO  - Appl Environ Microbiol 1993 Dec;59(12):4203-10