title: Impact of UV disinfection combined with chlorination/chloramination on the formation of halonitromethanes and haloacetonitriles in drinking water.
abstract: The application of UV disinfection in water treatment is increasing due to both its effectiveness against protozoan pathogens, and the perception that its lack of chemical inputs would minimize disinfection byproduct formation. However, previous research has indicated that treatment of nitrate-containing drinking waters with polychromatic medium pressure (MP), but not monochromatic (254 nm) low pressure (LP), UV lamps followed by chlorination could promote chloropicrin formation. To better understand this phenomenon, conditions promoting the formation of the full suite of chlorinated halonitromethanes and haloacetonitriles were studied. MP UV/postchlorination of authentic filter effluent waters increased chloropicrin formation up to an order of magnitude above the 0.19 μg/L median level in the U.S. EPA's Information Collection Rule database, even at disinfection-level fluences (<300 mJ/cm(2)) and nitrate/nitrite concentrations (1.0 mg/L-N) relevant to drinking waters. Formation was up to 2.5 times higher for postchlorination than for postchloramination. Experiments indicated that the nitrating agent, NO(2)(•), generated during nitrate photolysis, was primarily responsible for halonitromethane promotion. LP UV treatment up to 1500 mJ/cm(2) did not enhance halonitromethane formation. Although MP UV/postchloramination enhanced dichloroacetonitrile formation with Sigma-Aldrich humic acid, formation was not significant in field waters. Prechlorination/MP UV nearly doubled chloropicrin formation compared to MP UV/postchlorination, but effects on haloacetonitrile formation were not significant.
authors.affiliation: Department of Chemical and Environmental Engineering, Yale University , Mason Lab 313b, 9 Hillhouse Ave., New Haven, Connecticut 06520, United States.
authors.forename: Amisha D
authors.initials: AD
authors.lastname: Shah
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Dotson
authors.forename: Karl G
authors.initials: KG
authors.lastname: Linden
authors.forename: William A
authors.initials: WA
authors.lastname: Mitch
mesh_terms: D000097:Acetonitriles / Q000032:analysis / Q000138:chemical synthesis*; D004202:Disinfectants / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects; D004203:Disinfection / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D054879:Halogenation; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000138:chemical synthesis; D008697:Methane / Q000031:analogs & derivatives* / Q000032:analysis / Q000138:chemical synthesis; D009595:Nitroparaffins / Q000032:analysis / Q000138:chemical synthesis*; D055668:Photochemical Processes; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000138:chemical synthesis*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis
chemical_list: D000097:Acetonitriles; D004202:Disinfectants; D006843:Hydrocarbons, Chlorinated; D009595:Nitroparaffins; D014874:Water Pollutants, Chemical; C100187:chloropicrin; D008697:Methane; C008640:nitromethane