Disinfection Byproducts
Dr. Kimura-Hara and her group have a strong focus on DBP research, with over a dozen published papers on topics surrounding DBPs such as their formation, risk factors, and quantitative analysis. This is just a snapshot of some of her recent papers.
From Micropollutant to DBP Driver: The Unexpected Reactivity of 1-Chlorobenzotriazole in Water Disinfection
Kumudu H. Rathnayake, Md Fahim Hossain, Atlas Brown, Susana Y. Kimura*, “From Micropollutant to DBP Driver: The Unexpected Reactivity of 1-Chlorobenzotriazole in Water Disinfection”, Environmental Science & Technology 2025, 60 (1), 1218-1228. DOI: 10.1021/acs.est.5c11623
"The increasing adoption of potable wastewater reuse is challenged by persistent micropollutants─such as benzotriazole─which are poorly removed by conventional treatment and may produce toxic disinfection byproducts (DBPs). This study investigated benzotriazole chlorination and identified 1-chlorobenzotriazole as the primary product, formed preferentially under near-neutral to acidic pH and excess chlorine─conditions typical in disinfected water. The DBP formation potential of 1-chlorobenzotriazole was evaluated using two organic matter standards and secondary wastewater effluents and compared against chlorine and monochloramine. Surprisingly, 1-chlorobenzotriazole formed DBP levels comparable to or greater than those from chlorine, including trihalomethanes, haloaldehydes, haloketones, haloacetonitriles, and halonitromethanes. This reactivity is attributed to 1-chlorobenzotriazole’s ability to function as a free chlorine reservoir, sustaining chlorination reactions and promoting continued DBP formation─unlike inorganic N-halamines. DBP speciation was strongly pH-dependent and mirrored chlorine behavior, supporting the chlorine reservoir effect. Additionally, 1-chlorobenzotriazole exhibited precursor- and matrix-dependent reactivity, especially with complex matrices like secondary wastewater effluents, where it acted as both a chlorine source and a direct DBP precursor. Overall, this work provides the first detailed evaluation of 1-chlorobenzotriazole DBP formation potential, revealing an overlooked pathway for halogenated DBP production in water disinfection, and emphasizes the importance of considering benzotriazole transformation products in advanced reuse systems."
Formation potential and analysis of 32 regulated and unregulated disinfection by-products: Two new simplified methods
Jillian N. Murakami, Xu Zhang, Joanne Ye, Amy MacDonald, Jorge Pérez Pérez, David W. Kinniburgh, Susana Y. Kimura*, “Formation Potential and Analysis of 32 Regulated and Unregulated Disinfection By-Products: Two New Simplified Methods”, Journal of Environmental Sciences, 2022, 117, 209-221. DOI-https://doi.org/10.1016/j.jes.2022.04.037
"Water disinfection is an essential process that provides safe water by inactivating pathogens that cause waterborne diseases. However, disinfectants react with organic matter naturally present in water, leading to the formation of disinfection by-products (DBPs). Multi-analyte methods based on mass spectrometry (MS) are preferred to quantify multiple DBP classes at once however, most require extensive sample pre-treatment and significant resources. In this study, two analytical methods were developed for the quantification of 32 regulated and unregulated DBPs. A purge and trap (P&T) coupled with gas chromatography mass spectrometry (GC-MS) method was optimized that automated sample pre-treatment and analyzed volatile and semi-volatile compounds, including trihalomethanes (THMs), iodinated trihalomethanes (I-THMs), haloacetonitriles (HANs), haloketones (HKTs) and halonitromethanes (HNMs). LOQs were between 0.02-0.4 µg/L for most DBPs except for 8 analytes that were in the low µg/L range. A second method with liquid chromatography (LC) tandem mass spectrometry (MS/MS) was developed for the quantification of 10 haloacetic acids (HAAs) with a simple clean-up and direct injection. The LC-MS/MS direct injection method has the lowest detection limits reported (0.2-0.5 µg/L). Both methods have a simple sample pre-treatment, which make it possible for routine analysis. Hyperchlorination and uniform formation conditions (UFC) formation potential tests with chlorine were evaluated with water samples containing high and low TOC. Hyperchlorination formation potential test maximized THMs and HAAs while UFC maximized HANs. Ascorbic acid was found to be an appropriate quencher for both analytical methods. Disinfected drinking water from four water utilities in Alberta, Canada were also evaluated."
Disinfectant Byproducts in Water
Cristina Postigo, Josh M. Allen, Amy A. Cuthbertson, Maria Farre, Susana Y. Kimura, 2022. Disinfection Byproducts in Water, in: Fontanals N, Marce R M (Eds.), in Analytical Methods for Environmental Contaminants of Emerging Concern. (Book Chapter) Wiley: USA. DOI-https://doi.org/10.1002/9781119763895.ch9
"Disinfection byproducts (DBPs) form after the reaction of natural and anthropogenic organic matter and other inorganic substances present in water with the disinfectants used to inactivate pathogens. This chapter provides insights into the most common DBP classes regarding their chemical properties, environmental occurrence, and the most suitable methodologies for their reliable determination in water. It includes the halogenated DBP classes trihalomethanes, haloacetic acids, haloacetaldehydes, halobenzoquinones, haloacetonitriles, halonitromethanes, haloacetamides, and the non-halogenated DBP class nitrosamines. Liquid-liquid extraction is the most widely used extraction method due to its simplicity, low cost, and effectiveness in simultaneously extracting various DBP classes. Linearity is obtained in most analytical approaches with the internal standard calibration method. Known DBPs represent only a small fraction of the halogenated material formed during the disinfection process. The development of target multi-class methods is encouraged to obtain valuable information at once for many DBPs, minimizing economical and lab-effort resources."