Bioanalytical Assessment of the Formation of Disinfection Byproducts in a Drinking Water Treatment Plant

Abstract

Disinfection of drinking water is the most successful measure to reduce water-borne diseases and protect health. However, disinfection byproducts (DBPs) formed from the reaction of disinfectants such as chlorine and monochloramine with organic matter may cause bladder cancer and other adverse health effects. In this study the formation of DBPs through a full-scale water treatment plant serving a metropolitan area in Australia was assessed using in vitro bioanalytical tools, as well as through quantification of halogen-specific adsorbable organic halogens (AOXs), characterization of organic matter, and analytical quantification of selected regulated and emerging DBPs. The water treatment train consisted of coagulation, sand filtration, chlorination, addition of lime and fluoride, storage, and chloramination. Nonspecific toxicity peaked midway through the treatment train after the chlorination and storage steps. The dissolved organic matter concentration decreased after the coagulation step and then essentially remained constant during the treatment train. Concentrations of AOXs increased upon initial chlorination and continued to increase through the plant, probably due to increased chlorine contact time. Most of the quantified DBPs followed a trend similar to that of AOXs, with maximum concentrations observed in the final treated water after chloramination. The mostly chlorinated and brominated DBPs formed during treatment also caused reactive toxicity to increase after chlorination. Both genotoxicity with and without metabolic activation and the induction of the oxidative stress response pathway showed the same pattern as the nonspecific toxicity, with a maximum activity midway through the treatment train. Although measured effects cannot be directly translated to adverse health outcomes, this study demonstrates the applicability of bioanalytical tools to investigate DBP formation in a drinking water treatment plant, despite bioassays and sample preparation not yet being optimized for volatile DBPs. As such, the bioassays are useful as monitoring tools as they provide sensitive responses even at low DBP levels.

Enhanced coagulation with powdered activated carbon or MIEX® secondary treatment: A comparison of disinfection by-product formation and precursor removal

“…Samples were prepared for DBP analysis by liquideliquid salted microextraction, and analysis was by gas chromatography with electron-capture detection (GC-ECD), using a previously reported method (Neale et al, 2012). The reporting limit for all DBPs was 0.1 mg/L and the recovery for all analytes was between 70% and 130%.…”

Reducing disinfection byproduct formation potential using ozonation and biological drinking water treatment

“…The contribution of tBuOH to toxicity was not measured since it is expected to have been lost during SPE. Further details on the bioassays were reported previously (Farré et al 2013, Neale et al 2012, Yeh et al 2014. and THNMs (Bond et al 2011b, Krasner 2009, Singer et al 1999, Yang et al 2012a) by 192%, 133%, and 1079%, respectively.…”

“…The eluates were blown down to 200 µL, which generates a 2,500 concentration factor for those DBPs completely recovered through the process. This extraction procedure enriched only non-volatile DBPs while the more volatile compounds were likely lost during the blow-down step (Neale et al 2012). With the initial ~4-fold enrichment of DOC, the effects of treatment on the original settled water were highly magnified to the point of making any differences in biological effect more discernible.…”

“…These effects may not be easily determined using conventional analytical techniques. For this purpose, recent studies have shown that chemical analysis of DBPs can be complemented with bioanalytical tools such as in vitro bioassays to gain a better understanding of the transformations and toxicity that may occur after treatment (Farré et al 2013, Lyon et al 2014b, Neale et al 2012. These tools may also be useful in determining the effects of varying ozonation conditions on the quality of the final disinfected water.…”

Going Beyond the Analysis of Common Contaminants: Target, Suspect, and Non-Target Analysis of Complex Environmental Matrices by High-Resolution Mass Spectrometry

“…Moreover, a negative mass defect indicates the possible presence of elements such as halogens. Therefore, potentially harmful disinfection byproducts (which have been a topic of concern and interest with respect to advanced water treatment technologies (Neale et al, 2012;Postigo and Richardson, 2014)) could be present in this specific region of the Kendrick mass defect plot. When comparing the other three sampling sites (upstream, drinking water intake, and treated drinking water), the Kendrick mass defect plots (shown in Appendix 7) appear very similar, however the drinking water intake site appears to have the greatest number of components, most likely residual compounds introduced by the wastewater effluent, which are sufficiently removed in the subsequent drinking water treatment.…”