Modeling Cryptosporidium spp. Oocyst Inactivation in Bubble-Diffuser Ozone Contactors

The CT concept (product of disinfectant concentration and characteristic contact time) is currently used to demonstrate compliance with disinfection requirements for Giardia lamblia (G. lamblia) and viruses under the Surface Water Treatment Rule (SWTR). Minimum CT requirements include relatively lar...

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Bibliographic Details
Main Authors: Tomiak, Robert B, Rennecker, Jason L, Marinas, Benito J, Miltner, Richard J, Owens, James H
Format: Report
Language:English
Subjects:
CRYPTOSPORIDIUM MURIS
CRYPTOSPORIDIUM PARVUM
DISINFECTION
DRINKING WATER
Environmental Health and Safety
HEALTH RISK
INACTIVATION
MATHEMATICAL MODELS
OOCYSTS
PARASITES
PATHOGENIC MICROORGANISMS
PROTOZOA
PUBLIC HEALTH
SWTR(SURFACE WATER TREATMENT RULE)
Water Pollution and Control
WATER TREATMENT
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Summary:The CT concept (product of disinfectant concentration and characteristic contact time) is currently used to demonstrate compliance with disinfection requirements for Giardia lamblia (G. lamblia) and viruses under the Surface Water Treatment Rule (SWTR). Minimum CT requirements include relatively large safety factors to account for possible deviations from actual disinfection efficiencies achieved in full-scale contactors. The application of this conservative regulatory approach for Cryptosporidium parvum (C. parvum) might result in unrealistic disinfection requirements under the Enhanced SWTR due to the much stronger resistance of this protozoan parasite to inactivation by all chemical disinfectants used in drinking water applications. There is a need for the development of approaches that could provide a more accurate assessment of actual inactivation efficiency achieved in disinfection contactors. The main objective of this study is to develop and apply a mathematical model for predicting the inactivation of Cryptosporidium spp. (C. parvum and C. muris) oocysts in ozone bubble-diffuser contactors. The model is calibrated with semi-batch kinetic data, verified with pilot-scale inactivation experiments, and used for predicting and optimizing full-scale disinfection efficiency. Prepared in collaboration with National Risk Management Research Lab., Cincinnati, OH.