AWWA WQTC64008

The work described in this paper has been undertaken to validate the CT values of the ozone contactors of the DesBaillets (1136 MLD) water treatment plant (Montreal, Quebec, Canada) by means of a biodosimetric technique. Indigenous aerobic spore formers (ASF) were used as surrogates for monitoring disinfection efficacy. Four biodosimetric assays were completed on-site over a 6-week period. The approach developed involved the implementation of reference biodosimetric curves followed by the full-scale validations. Reference biodosimetric curves were generated using an ozone pilot apparatus (18 Lpm). A precise measurement of ASF inactivation was obtained using a high-volume filtration technique (10 L). The following day, full-scale ozone experiments were performed. Those assays also enabled the calculation of the regulatory CT₁0 and the CT_IDDF values. The effective CT was calculated based on the reference curve developed on the pilot contactor. CT values were then compared to evaluate the accuracy of the models and validate their predictions. Includes 20 references, figures.