Author(s): Manuel Rodriguez

Linked Author(s): Manuel Rodriguez

Keywords: Water supply; Source water; Contaminants; Spatio-temporal Dat

Abstract: In many countries, regulatory requirements concerning drinking water stipulate the necessity for implementing strategies and developing tools to reduce the presence of chemical contaminants, while maintaining microbiological integrity without compromising the aesthetic quality of drinking water. This challenge is all the more important given the deterioration of source water quality (increasing presence of organic and inorganic contaminants), the difficulty to remove DBP precursors in water treatment plants, and the increasing complexity of distribution networks (network interconnections, reservoir upgrades, secondary disinfection within networks, etc.). Better knowledge of emerging contaminants and the factors governing their spatio-temporal variability would allow managers to take steps to reduce these contaminants, but also to implement better monitoring strategies. In the past eight years, we have carried out an intensive sampling and laboratory program in about forty municipal drinking water systems of Canada to monitor and evaluate the levels of various contaminants of emerging interest. The municipal systems were selected in accordance with the type of source watersheds, types of treatment and disinfection strategy, size and hydraulic characteristics of the distribution system, past information on regulated DBPs and presence of specific precursors is source waters. Monitoring was conducted at various moments of the year to take into account seasonal water quality and temperature pattern changes, and at various locations within the treatment plant and the distribution extremities to take into account the residence time of water within the municipal network. We have focused on the following compounds found at very low concentration levels in drinking water (from ng/L to few ug/L):, haloacetonitriles, halonitromethanes, haloketones, aldehydes, Iodinated THMs and HAAs, N-nitrosamines, chlorite, chlorate, bromate. These data obtained was analyzed using appropriate multivariate statistical models to explain the contribution of individual operational and water quality parameters to the variability of the various emerging DBPs. The results show that despite the very low concentrations of these compounds, their levels change considerably according to the residence time of water and the period of the year. It was observed that the patterns for spatial and temporal variations are not comparable between the different species of emerging contaminants. Indeed these patterns for emerging DBP variability are mainly associated to the variability of their precursors in source water, the operational conditions at the treatment plant, and the hydraulic characteristics of the distribution systems. This database on emerging DBPs also served to identify of representative time/space monitoring strategies, and to compare them to strategies already applied to regulated contaminants. This research also demonstrated the relevance of generating robust spatio-temporal databases to adequately assess population exposure to conta

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221163

Year: 2022