CAREER: Development of a Novel Approach for the Identification of Toxic Byproducts and their Precursors in Oxidative Drinking Water Treatment

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Chemical oxidants such as chlorine, chloramine, ozone, and hydrogen peroxide are widely used in water treatment as disinfectants to deactivate pathogens and as reactants to abate organic contaminants in drinking water sources. These chemical oxidants can also react with organic contaminants and dissolved organic matter (DOM) to generate byproducts which can adversely impact human health due to their potential toxicity. Currently, hundreds of byproducts have been detected in treated drinking water. However, only a limited number of these byproducts have been evaluated for toxicity as the current protocols used to assess their toxicity rely on a slow and inefficient chemical-by-chemical evaluation approach. The overarching goal of this CAREER project is to develop a novel approach to identify toxic byproducts and their precursors in drinking water treated with chemical oxidants. This novel approach, reactivity-directed analysis (RDA), builds upon techniques and protocols pioneered in drug development and chemical risk assessment to identify all byproducts with simar mechanisms of toxicity in a sample of drinking water treated with chemical oxidants. The successful completion of this project will benefit society through the generation of new fundamental knowledge to understand, control, and mitigate the formation of toxic byproducts and their precursors in drinking water treated with chemical oxidants. Further benefits to society will be achieved through student education and training including the mentoring of a graduate student at Johns Hopkins University. Chemical oxidants used in water treatment react with organic contaminants and dissolved organic matter (DOM) in drinking water sources to generate a large variety of byproducts. However, a comprehensive assessment of the toxicity of drinking water byproducts has remained elusive. This CAREER project will address this critical knowledge gap. To advance this goal, the Principal Investigator (PI) proposes to develop and apply a novel approach to detect toxic byproducts, called reactivity-directed analysis (RDA). This innovative approach leverages assays and protocols pioneered in drug development and chemical risk assessment to identify toxic organic electrophiles (the largest class of known toxicants) in treated drinking water and elucidate their precursors. The specific objectives of the proposed research are to: 1) Develop a novel microbead-based RDA assay for the detection of organic electrophiles in complex aqueous matrices, 2) Investigate the formation and reaction mechanisms of organic electrophiles produced from the reaction of phenolic DOM model compounds with chemical oxidants, and 3) Investigate the formation of organic electrophiles produced from the reactions of DOM isolates, treated wastewater, and surface water with chemical oxidants. The successful completion of this project has the potential for transformative impact through the generation of fundamental knowledge to advance the development and implementation of a new framework for identifying toxic byproducts and their precursors that could be used to minimize and mitigate their formations in drinking water treatment systems. To implement the educational and training goals of this CAREER project, the PI will leverage his ongoing collaboration with The Food Project (TFP) to develop and implement an afterschool program (EnviroSense) that will expose middle and high-school students to the design and applications of water quality sensors. In addition, the PI plans to develop two new courses including an undergraduate lab course on water quality sensors and a graduate course on water quality assessment and monitoring.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.