Novel Analytical Method for Trace Level Quantification of Disinfection By-Products in Recycled Wastewaters
Date
2020-12-08
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Abstract
The work of this thesis quantifies and characterizes unregulated priority disinfection by-products (DBPs) in a full-scale potable wastewater reuse treatment plant. DBPs are small organic molecules formed from the reaction between natural organic matter (NOM) and disinfectants. Unregulated DBPs display genotoxic, cytotoxic and potentially carcinogenic properties to humans. Wastewater reuse is an area of growing interest as freshwater sources are being depleted due to increasing human population and climate change. Secondary effluent treated with microfiltration (UF), ozone, and reverse osmosis waters were disinfected to observe the change in DBP composition throughout various stages of the treatment train process. First, a novel multiple reaction monitoring (MRM) method was developed on a gas chromatography – triple quadrupole mass spectrometer (GC-MS/MS) that quantifies 25 DBPs formed from chlorinated and chloraminated wastewater effluents. The order of optimization of each DBP class involved the determination of chemical transitions, collision energies, dwell times, time segments and determination of method detection limits. The optimization of these parameters led to a highly sensitive quantification method for the DBPs found in this method. Method detection limits ranged from 2.0 - 68.9 ng/L. Next, a liquid – liquid extraction (LLE) method for sample analysis was modified to account for the large increase in sensitivity that comes with a triple quadrupole. MS/MS instruments are highly advantageous because of the selection of specific chemical transitions for quantification. This specificity results in precise quantification due to the large signal to noise ratio of each chemical fragment at trace levels. The LLE method was reduced 10 fold in terms of time, reagents, and sample volume compared to published methods. The last part of this work looked at the DBP composition of each water matrix across three seasons of the year. Specifically, waters were sampled in fall, winter, and summer to observe how the change in precursors affected DBP formation.
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Keywords
Disinfection By-products, DBPs, Wastewater Reuse, Analytical Chemistry
Citation
Ortega, A. R. (2020). Novel Analytical Method for Trace Level Quantification of Disinfection By-Products in Recycled Wastewaters (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.