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

摘要

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. 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.