title: Disinfection byproduct formation during biofiltration cycle: Implications for drinking water production.
abstract: The goal of this study was to investigate the potential of biofiltration to reduce the formation potential of disinfection byproducts (DBPs). Particularly, the work investigates the effect of the duration of the filter cycle on the formation potential of total trihalomethanes (TTHM) and five species of haloacetic acids (HAA5), dissolved oxygen (DO), organic carbon, nitrogen and total phosphorous concentrations along with biofilm coverage of the filter media and biomass viability of the attached cells. The study was conducted on a full-scale biologically active filter, with anthracite and sand media, at the Britannia water treatment plant (WTP), located in Ottawa, Ontario, Canada. The formation potential of both TTHMs and HAA5s decreased due to biofiltration. However the lowest formation potentials for both groups of DBPs and or their precursors were observed immediately following a backwash event. Hence, the highest percent removal of DBPs was observed during the early stages of the biofiltration cycle, which suggests that a higher frequency of backwashing will reduce the formation of DBPs. Variable pressure scanning electron microscopy (VPSEM) analysis shows that biofilm coverage of anthracite and sand media increases as the filtration cycle progressed, while biomass viability analysis demonstrates that the percentage of cells attached to the anthracite and sand media also increases as the filtration cycle progresses. These results suggest that the development and growth of biofilm on the filters increases the DPB formation potential.
authors.affiliation: Department of Civil Engineering, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada. Electronic address: robert.delatolla@uottawa.ca.
authors.forename: R
authors.initials: R
authors.lastname: Delatolla
authors.affiliation: Department of Civil Engineering, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Séguin
authors.affiliation: Center for Research on Environmental Microbiology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Springthorpe
authors.affiliation: City of Ottawa, Ottawa, Ontario K1P 1J1, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Gorman
authors.affiliation: City of Ottawa, Ottawa, Ontario K1P 1J1, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Campbell
authors.affiliation: City of Ottawa, Ottawa, Ontario K1P 1J1, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Douglas
mesh_terms: D002170:Canada; D004202:Disinfectants / Q000032:analysis*; D004203:Disinfection / Q000379:methods; D060766:Drinking Water / Q000032:analysis / Q000737:chemistry*; D005374:Filtration; D009584:Nitrogen / Q000032:analysis; D009864:Ontario; D012822:Silicon Dioxide / Q000032:analysis; D022882:Trihalomethanes / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D004202:Disinfectants; D060766:Drinking Water; D022882:Trihalomethanes; D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide; D009584:Nitrogen
keywords: Biofilm; Biofiltration; Disinfection byproducts; Filtration cycle; Total organic carbon