title: Engineered biofiltration for the removal of disinfection by-product precursors and genotoxicity.
abstract: Disinfection by-products (DBPs) are formed when naturally occurring organic matter reacts with chlorine used in drinking water treatment, and DBPs formed in chlorinated drinking water samples have been shown to cause a genotoxic response. The objective of the current study was to further understand the principles of biofiltration and the resulting impacts on the formation of DBPs and genotoxicity. Pilot-scale systems were utilized to assess the performance of engineered biofilters enhanced with hydrogen peroxide, in-line coagulants, and nutrients when compared to passively operated biofilters and conventional treatment (coagulation, flocculation, sedimentation, non-biological filtration). Organic fractionation was completed using liquid chromatography-organic carbon detection (LC-OCD). Water samples were chlorinated after collection and examined for the removal of trihalomethane (THM), haloacetic acid (HAA), and adsorbable organic halide (AOX) precursors. Additionally, the formation potential of two halogenated furanones, 3-chloro-4(dichloromethyl)-2(5H)-furanone (MX) and mucochloric acid (MCA), and genotoxicity was determined. Biofiltration was shown to preferentially remove more DBP precursors than dissolved organic carbon (DOC). Formation potential of the unregulated DBPs, including MX and MCA, and genotoxic response was shown to be correlated to THM formation. These results infer that monitoring for THMs and HAAs provide insight to the formation of more mutagenic DBPs such as halogenated furanones, and that biofiltration may preferentially remove precursors to DBPs at a rate exceeding the removal of DOC.
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada. Electronic address: m.mckie@mail.utoronto.ca.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKie
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Liz
authors.initials: L
authors.lastname: Taylor-Edmonds
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
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 M5S 1A4, Canada.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Andrews
mesh_terms: D018441:Biofilms; D004203:Disinfection; D060766:Drinking Water / Q000737:chemistry; D005374:Filtration / Q000379:methods*; D005663:Furans / Q000737:chemistry; D054879:Halogenation; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D009152:Mutagenicity Tests; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D005663:Furans; D006843:Hydrocarbons, Chlorinated; D014874:Water Pollutants, Chemical
keywords: Disinfection by-products (DBPs); Drinking water; Engineered biofiltration; Genotoxicity; Halogenated furanones; Natural organic matter (NOM)