Estimation of Giardia Ct values at high pH for the Surface Water Treatment Rule.

Abstract

The U.S. Environmental Protection Agency currently recommends Ct (disinfectant concentration multiplied by the exposure time) values to achieve required levels of inactivation of Giardia lamblia cysts by different disinfectants including free chlorine. Current guidance covers inactivation levels in the pH range between 6 and 9. Subsequent to the publication of these criteria, studies on the inactivation kinetics of Giardia cysts by chlorine have been performed at pH levels greater than 9. It has been shown that the chlorine inactivation process for Giardia cysts is pH dependent. The objective of this paper is to extend the current Ct values for higher pH levels. The Chick-Watson first order kinetics model was used to develop Ct values for pH levels from 6 to 11.5. A formula is provided to calculate a 100(1 - alpha)% upper confidence bound for these values.

• Authors: Mano Sivaganesan, Eugene W Rice
• Journal: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering (J Environ Sci Health A Tox Hazard Subst Environ Eng) Vol. 38 Issue 9 Pg. 1959-70 (Sep 2003) ISSN: 1093-4529 [Print] England
• PMID: 12940495 (Publication Type: Journal Article)

Chemical References

• Disinfectants
• Chlorine

Topics

• Animals
• Chlorine (pharmacology)
• Disinfectants (pharmacology)
• Disinfection (standards)
• Forecasting
• Giardia (pathogenicity)
• Guideline Adherence
• Hydrogen-Ion Concentration
• Kinetics
• Models, Theoretical
• Oocysts
• Water Purification (standards)