Research Themes
DBP precursors, formation, and toxicity
Disinfection byproducts (DBP) form when drinking water is disinfected for pathogen inactivation, posing potential chronic health risks as probable carcinogens. Our lab seeks to better understand how variations in the source water characteristics and treatment trains impact which and how many DBPs are formed. The primary precursor of DBPs in surface water is natural organic matter (NOM). The character and quantity of NOM in surface water is shifting with climate change and population growth, such as increases in algal blooms and wastewater effluent. Studying variations in molecular weight, hydrophobicity, molecular composition, and environmental transformations through processes like photolysis is critical to better predict and control DBP formation in drinking water systems.
Feasibility of single-stage softening during water treatment
Ann Arbor Water established a pilot-scale treatment facility to evaluate candidate technologies for future plant upgrades. The pilot plant was operated in partnership with the City of Ann Arbor, University of Michigan, and AECOM. Further investigation for the pilot plant operation was performed through collaboration with Jacobs. The pilot treatment train consisted of single-stage softening using a solids-contact clarifier, followed by ozonation and ozone/hydrogen peroxide processes, and granular activated carbon (GAC) filtration. Softening performance was evaluated under multiple chemical regimes, including excess lime, soda ash, caustic, and metal-based coagulants. Key water quality parameters, such as pH, hardness, alkalinity, turbidity, dissolved organic carbon (DOC), and UV254 were monitored. In addition, targeted trace-organic contaminant testing was conducted, including 1,4-dioxane, per- and polyfluoroalkyl substances (PFAS), and disinfection by-products (DBPs).
Investigating the Effect of Operational Strategies and the Role of Microbial Biomass for Extending the Lifetime of Granular Activated Carbon
GAC is the industry standard for effectively removing PFAS, disinfectant byproduct (DBP) precursors, and other contaminants from water systems. Its performance is influenced by the microbial biomass that naturally develops during operation. This biomass can both hinder PFAS adsorption through pore blockage and enhance removal through biosorption and biodegradation of competing organic matter. This bioactivity also has the potential to increase n-DBP formation, underscoring the complex role of biomass in contaminant control and GAC lifespan. Utilities employ varied operational strategies, such as oxidant pretreatment, biological filtration pretreatment, and chlorinated backwash, to influence biomass levels and activity, yet their effects on PFAS and n-DBP removal remain poorly understood. This project examines how operational parameters influence contaminant control by GAC filters at four full-scale utilities and in a pilot-scale system, focusing on PFAS, unregulated n-DBPs, and DBP precursors.