Fluorescent dissolved organic matter components as surrogates for disinfection byproduct formation in drinking water: a critical review

Disinfection byproduct (DBP) formation, prediction, and minimization are critical challenges facing the drinking water treatment industry worldwide where chemical disinfection is required to inactivate pathogenic microorganisms. Fluorescence excitation–emission matrices-parallel factor analysis (EEM-PARAFAC) is used to characterize and quantify fluorescent dissolved organic matter (FDOM) components in aquatic systems and may offer considerable promise as a low-cost optical surrogate for DBP formation in treated drinking waters. However, the global utility of this approach for quantification and prediction of specific DBP classes or species has not been widely explored to date. Hence, this critical review aims to elucidate recurring empirical relationships between common environmental fluorophores (identified by PARAFAC) and DBP concentrations produced during water disinfection. From 45 selected peer-reviewed articles, 218 statistically significant linear relationships (R2 ≥ 0.5) with one or more DBP classes or species were established. Trihalomethanes (THMs) and haloacetic acids (HAAs), as key regulated classes, were extensively investigated and exhibited strong, recurrent relationships with ubiquitous humic/fulvic-like FDOM components, highlighting their potential as surrogates for carbonaceous DBP formation. Conversely, observed relationships between nitrogenous DBP classes, such as haloacetonitriles (HANs), halonitromethanes (HNMs), and N-nitrosamines (NAs), and PARAFAC fluorophores were more ambiguous, but preferential relationships with protein-like components in the case of algal/microbial FDOM sources were noted. This review highlights the challenges of transposing site-specific or FDOM source-specific empirical relationships between PARAFAC component and DBP formation potential to a global model

A validated reverse-phase LC-MS/MS method for the analysis of haloacetic acids in drinking water: supporting the transition from HAA5 to HAA9

Haloacetic acids (HAAs) are potentially toxic by-products formed from interactions between organic matter and chlorine during disinfection of drinking water, with brominated HAAs forming when bromide is present. Some countries require monitoring of drinking water for five HAAs, but there is increasing health concern related to the more toxic brominated HAAs and monitoring of nine HAAs (HAA9) is becoming more widespread. However, existing methods of analysis for HAA9 are often sub-optimal, involving complex derivatisation steps and/or long analytical run times. This article presents an improved methodology utilising reverse-phase liquid chromatography mass spectrometry (LC-MS/MS) for which sample preparation involves simple pH adjustment and the analytical run takes 10 min. The efficacy of the method was demonstrated by a full validation across four drinking water matrices with good sensitivity (<0.8 μg/L), precision (<7%), and bias (<10%) observed. A direct comparison using real water samples was performed against the widely used existing gas chromatography method. The new LC-MS/MS method was significantly quicker and easier and demonstrated improved performance in terms of accuracy and precision. This has implications for understanding the risk posed by HAAs in chlorinated water by eliminating the possible historical under-estimates of the levels of the more toxic brominated compounds.The work was supported by UK Water Industry Research Ltd (UKWIR) and Engineering and Physical Sciences Research Council (EPSRC) through their funding of the Water Infrastructure and Resilience (WIRe) Centre for Doctoral Training [EP/5023666/1]

Sorptive removal of disinfection by-product precursors from UK lowland surface waters: impact of molecular weight and bromide

The current study compared the impact of three different unit processes, coagulation, granular activated carbon (GAC), and a novel suspended ion exchange (SIX) technology, on disinfection by-product formation potential (DBPFP) from two UK lowland water sources with medium to high bromide content. Specific attention was given to the influence of the organic molecular weight (MW) fraction on DBPFP as well as the impact of bromide concentration. Whilst few studies have investigated the impact of MW fractions from Liquid Chromatography with Organic Carbon Detection (LC-OCD) analysis on dissolved organic carbon (DOC) removal by different processes, none have studied the influence of DOC MW fractions from this analysis on DBP formation. The impact of higher bromide concentration was to decrease the total trihalomethane (THM) and haloacetic acid (HAA) mass concentration, in contrast to previously reported studies. Results indicated that for a moderate bromide concentration source (135 μg/L), the THM formation potential was reduced by 22% or 64% after coagulation or SIX treatment, respectively. For a high bromide content source (210 μg/L), the THM formation potential removal was 47% or 69% following GAC and SIX treatment, respectively. The trend was the same for HAAs, albeit with greater differences between the two processes/feedwaters with reference to overall removal. A statistical analysis indicated that organic matter of MW > 350 g/mol had a significant impact on DBPFP. A multiple linear regression of the MW fractions against DBPFP showed a strong correlation (R2 between 0.90 and 0.93), indicating that LC-OCD analysis alone could be used to predict DBP formation with reasonable accuracy, and offering the potential for rapid risk assessment of water source

A critical review of trihalomethane and haloacetic acid formation from natural organic matter surrogates

Disinfection by-products (DBPs) in drinking water, including trihalomethanes (THMs) and haloacetic acids (HAAs), arise from reactions of natural organic matter (NOM) with chlorine and other disinfectants. The objective of this review was to investigate relationships between the molecular properties of NOM surrogates and DBP formation using data collated for 185 compounds. While formation of THMs correlated strongly with chlorine substitution, no meaningful relationships existed between compound physicochemical properties and DBP formation. Thus non-empirical predictors of DBP formation are unlikely in natural waters. Activated aromatic compounds are well known to be reactive precursors; in addition DBP formation from β-dicarbonyl, amino acid and carbohydrate precursors can be significant. Therefore effective DBP control strategies need to encompass both hydrophobic and hydrophilic NOM components, as well as consider data from NOM surrogates in the context of knowledge from representative treatment scenarios. In future experiments, employing surrogates of NOM is likely to remain a powerful tool in the search for unknown precursors and in understanding their response to various disinfection conditions

A critical review of trihalomethane and haloacetic acid formation from natural organic matter surrogates

Disinfection by-products (DBPs) in drinking water, including trihalomethanes (THMs) and haloacetic acids (HAAs), arise from reactions of natural organic matter (NOM) with chlorine and other disinfectants. The objective of this review was to investigate relationships between the molecular properties of NOM surrogates and DBP formation using data collated for 185 compounds. While formation of THMs correlated strongly with chlorine substitution, no meaningful relationships existed between compound physicochemical properties and DBP formation. Thus non-empirical predictors of DBP formation are unlikely in natural waters. Activated aromatic compounds are well known to be reactive precursors; in addition DBP formation from β-dicarbonyl, amino acid and carbohydrate precursors can be significant. Therefore effective DBP control strategies need to encompass both hydrophobic and hydrophilic NOM components, as well as consider data from NOM surrogates in the context of knowledge from representative treatment scenarios. In future experiments, employing surrogates of NOM is likely to remain a powerful tool in the search for unknown precursors and in understanding their response to various disinfection conditions

Parameters affecting haloacetic acid and trihalomethane concentrations in treated UK drinking waters

Since their discovery, disinfection by-products (DBPs) have become one of the major driving forces in drinking water regulations, research and water utility operations throughout the world. The list of DBPs that can occur in treated drinking waters has grown from a few trihalomethanes to a long list of halogenated and non-halogenated organic or inorganic compounds. This list is expected to continue to grow as the analytical techniques are improved, as more information on their toxicity is developed, and as more occurrence studies are conducted. This book documents the latest DBP research findings, including emerging issues and state-of-the-art studies. Specifically, papers on the occurrence, formation, control, and health effects of emerging (unregulated) halogenated (e.g., brominated) and nonhalogenated (e.g., nitrosamines) DBPs (e.g., emerging nitrogenous vs. regulated carbonaceous DBPs) are presented. In addition to the characterization and reactivity of natural organic matter to form DBPs, new studies on algal organic matter and treated wastewater as sources of DBPs and their precursors are discussed

Disinfection by-product occurrence in selected European waters

International audienc

Disinfection by-product occurrence in selected European waters

In this paper we report the findings of a European survey of regulated and emerging disinfection by-products (DBPs) in drinking waters in selected regions that were part of epidemiology studies. The levels of DBPs found reflected the diverse regions from which the samples were collected, the different treatment/disinfection processes and the different source waters. In addition to a wide range of concentrations of DBPs (e.g. median trihalomethanes (THMs) of 8–85 μg L–1), bromine incorporation was quite diverse (e.g. some waters were highly dominated by bromine-containing DBPs, whereas others only had chlorine-containing species). Bromine incorporation was highest in the haloacetonitriles (HANs) and was lowest in the trihalogenated haloacetic acids (THAAs). In addition, the ratios of THMs to HAAs, THMs to HANs, and THAAs to dihalogenated HAAs varied. Exposure assessment based on THMs alone was not sufficient for indicating the presence of emerging DBPs of health concern. Occurrence studies must include a more diverse group of analytes to better understand exposure to DBPs of health concernAplinkotyros katedraVytauto Didžiojo universiteta

Disinfection by-product occurrence in selected European waters

In this paper we report the findings of a European survey of regulated and emerging disinfection by-products (DBPs) in drinking waters in selected regions that were part of epidemiology studies. The levels of DBPs found reflected the diverse regions from which the samples were collected, the different treatment/disinfection processes and the different source waters. In addition to a wide range of concentrations of DBPs (e.g. median trihalomethanes (THMs) of 8-85 mu g L-1), bromine incorporation was quite diverse (e.g. some waters were highly dominated by bromine-containing DBPs, whereas others only had chlorine-containing species). Bromine incorporation was highest in the haloacetonitriles (HANs) and was lowest in the trihalogenated haloacetic acids (THAAs). In addition, the ratios of THMs to HAAs, THMs to HANs, and THAAs to dihalogenated HAAs varied. Exposure assessment based on THMs alone was not sufficient for indicating the presence of emerging DBPs of health concern. Occurrence studies must include a more diverse group of analytes to better understand exposure to DBPs of health concern