Date of Award
Open Access Dissertation
Chemistry and Biochemistry
Susan D. Richardson
Drinking water disinfection is considered one of the greatest scientific achievements of the 20th Century because it significantly reduced the number of deaths related to waterborne diseases. However, in 1974 J.J. Rook discovered that chlorine, a commonly used disinfectant, can react with natural organic matter to form disinfection byproducts (DBPs). Since then, more than 700 DBPs have been identified, with several epidemiological and toxicological studies linking DBPs to several adverse health effects such as bladder and colorectal cancer, adverse birth outcomes, and asthma. Due to their ubiquity in disinfected water and their adverse health effects, studying the formation and identifying new DBPs is critical to identifying the drivers of toxicity in disinfected water and ultimately improving water quality. The studies presented here utilized highly sensitive analytical methods and instruments to quantify DBPs in a variety of matrices, including wastewater treatment plant effluent and swimming pools. Further, the third study utilizes high-resolution mass spectrometry to identify unknown haloaromatic DBPs in tea.
Comprehensive DBP analysis of chlorinated wastewater treatment plant effluent and upstream/downstream river samples revealed that a variety of DBPs are formed during the disinfection step at wastewater treatment plants. Interestingly, in vitro studies reveal that nitrogenous DBPs (haloacetonitriles and haloacetamides) and haloketones are important drivers of cytotoxicity and genotoxicity, respectively, in samples collected downstream from wastewater treatment plants.
Extensive DBP analysis of conventional chlorine and salt water pool samples revealed that haloacetonitriles, haloacetic acids, and haloacetaldehydes were the primary drivers of calculated cytotoxicity, while haloacetic acids were the primary drivers of calculated genotoxicity. This study also provides an important comparison between conventional chlorine (liquid bleach) and electrochemically generated chlorine (salt water pool), two common disinfection techniques used in swimming pools. Results reveal the importance of maintaining a low residual of chlorine and ensuring proper ventilation to reduce swimmers’ exposure to DBPs.
Unknowns analysis using high-resolution mass spectrometry revealed six newly identified DBPs in brewed tea, including two monochloro-hydroxyphenols, two monochloro-trihydroxybenzenes, and two dichloro-trihydroxybenznenes. The identification of haloaromatic DBPs is significant due to recent studies noting that they can be more toxic than aliphatic DBPs.
Overall, results from these studies reveal that nitrogenous DBPs are important drivers of toxicity in both river samples receiving wastewater treatment plant effluent and swimming pools. Additionally, unknowns analysis of tea emphasizes the importance of continuing to identify new DBPs due to their potential for elevated toxicity.
Granger, C. O.(2022). Disinfection Byproducts in Wastewater, Swimming Pools, and Tea: Identification, Quantification, and Drivers of Toxicity. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/6989