UBC Theses and Dissertations
Assesment of drinking water quality using disinfection by-products in a distribution system following a treatment technology upgrade Bush, Kelly Lynn
Chlorine is the most widely used disinfectant for drinking water treatment. Chlorine canreact with natural organic matter (NOM) in water sources resulting in the formation of potentially carcinogenic disinfection by-products (DBPs). The most common DBPs measured in chlorinated drinking water distribution systems are trihalomethanes (THMs) and haloacetic acids (HAAs). In 2005, the City of Kamloops, British Columbia upgraded the drinking water treatment system to ultrafiltration membrane treatment. The objective of this study was to determine the extent to which upgrades to a drinking water treatment system, specifically, implementation of an ultrafiltration treatment process, impacted DBP formation within a distribution system. This study used a two-phase research approach. Phase I of the study was a distribution system monitoring program that collected water samples and physical and chemical information using data loggers at five sampling sites within the distribution system. Phase II of the study used bench-scale simulations that modeled DBP formation using a flow-through reactor system, the material-specific simulated distribution system (MS-SDS), constructed of pipe material resurrected from the City of Kamloops distribution system. Phase I results suggested that implementation of the ultrafiltration treatment process and accompanying treatment system upgrade was not effective at reducing the concentration of DBPs delivered to consumers. Concentrations of THMs remained relatively constant at sampling sites, while concentrations of HAAs increased following implementation of the ultrafiltration treatment process. The increase in HAA formation was likely due to an increase in retention time of the water within the distribution system following implementation of the ultrafiltration treatment process, rather than due to the treatment process itself. The results of this study are consistent with previous work on South Thompson River water DBP precursors, which suggested that THM and HAA precursors of this source water are small and hydrophilic, and therefore cannot be removed by ultrafiltration processes. Phase II results showed that the MS-SDS was more representative of distribution system c onditions than traditional glass bottles to estimate DBP formation. It is recommended that the MS-SDS be used in parallel with a simultaneous distribution system monitoring program to estimate distribution system retention times from THM and HAA concentrations.
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