Modelling chlorine dioxide's inactivation of microbial indicators and disinfection by-product formation

grantor: University of TorontoThe application of chlorine dioxide to drinking water treatment was studied at bench- and pilot-scale during this research. The impact of water quality parameters including bromide level, pH, chlorine dioxide dose and purity, and secondary disinfectant type on the formation of disinfection by-product (DBP) was examined by performing 2-level factorial experiments DBPs measured during the experiments included chlorite, chlorate, trihalomethanes, haloacetic acids, bromate and adsorbable organic halides. Results showed that both pH and chlorine dioxide dose had the greatest impact on chlorite and chlorate. In addition, site-specific mathematical models which incorporated disinfectant chemistry characteristics, inactivation kinetics and contactor hydraulics to accurately estimate the inactivation of stressed and non-stressed microbial indicators (MS 2 phages and 'Bacillus subtilis' spores) for ' Giardia lamblia' and 'Cryptosporidium parvum' were developed. Results revealed that filtration/physical stress damaged the microbial cell membrane thereby rendering the microorganisms more susceptible to chlorine dioxide inactivation.M.A.Sc