title: Effects of coagulation on the removal of natural organic matter, genotoxicity, and precursors to halogenated furanones.
abstract: Natural organic matter (NOM) in drinking water can react with disinfectants to form disinfection by-products (DBPs). Halogenated furanones are a group of emerging DBPs that can account for 20-60% of the total mutagenicity observed in drinking water. This study examined the impacts of bench-scale coagulation and subsequent chlorination on DBP formation as well as genotoxicity using three source waters located in Ontario, Canada. Two halogenated furanones 3-chloro-4-(dichloromethyl)-2(5H)-furanone (MX) and mucochloric acid (MCA) were analyzed; along with trihalomethanes (THMs), haloacetic acids (HAAs), and absorbable organic halides (AOX). NOM was quantified using liquid chromatography-organic carbon detection (LC-OCD). Measured MX and MCA formation was 6.9-15.3 ng/L and 43.2-315 ng/L following optimized coagulation and subsequent chlorination of the three waters tested. DBP formation and speciation were evaluated as a function of the specific NOM fractions present in the source waters. Humics, building blocks, and biopolymers were highly correlated with DBP formation. Correlations between DBPs were also investigated and a potential relationship between MCA and/or MX vs. HAAs was observed. MX was the only measured DBP that contributed to genotoxicity, representing less than 0.001% of AOX by mass but responsible for 40-67% of the genotoxic response in chlorinated Ottawa River water samples. Genotoxic potential decreased with alum dosages, signifying that coagulation was effective at removing genotoxic DBP precursors.
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, Canada M5S 1A4. Electronic address: dana.zheng@utoronto.ca.
authors.forename: Dana
authors.initials: D
authors.lastname: Zheng
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, Canada M5S 1A4. Electronic address: andrews@ecf.utoronto.ca.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Andrews
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, Canada M5S 1A4.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Andrews
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, Canada M5S 1A4.
authors.forename: Liz
authors.initials: L
authors.lastname: Taylor-Edmonds
mesh_terms: D060766:Drinking Water / Q000737:chemistry; D005663:Furans / Q000737:chemistry / Q000494:pharmacology*; D006219:Halogens / Q000737:chemistry*; D009153:Mutagens / Q000633:toxicity*
chemical_list: D060766:Drinking Water; D005663:Furans; D006219:Halogens; D009153:Mutagens
keywords: Chlorination; Coagulation; Disinfection by-products (DBPs); Genotoxicity; Halogenated furanones; Natural organic matter (NOM)