title: Inactivation of Bacillus subtilis spores and formation of bromate during ozonation.
abstract: Inactivation of B. subtilis spores with ozone was investigated to assess the effect of pH and temperature, to compare the kinetics to those for the inactivation of C. parvum oocysts, to investigate bromate formation under 2-log inactivation conditions, and to assess the need for bromate control strategies. The rate of B. subtilis inactivation with ozone was independent of pH, decreased with temperature (activation energy of 42,100 Jmol(-1)), and was consistent with the CT concept. B. subtilis was found to be a good indicator for C. parvum at 20-30 degrees C, but at lower temperatures B. subtilis was inactivated more readily than C. parvum. Bromate formation increased as both pH and temperature increased. For water with an initial bromide concentration of 33 microgl(-1), achieving 2-logs of inactivation, without exceeding the 100 microg l(-1) bromate standard, was most difficult at 30 degrees C for B. subtilis and at midrange temperatures (10-20 degrees C) for C. partum. pH depression and ammonia addition were found to reduce bromate formation without affecting B. subtilis inactivation, and may be necessary for waters containing more than 50 microgl(-1) bromide.
authors.affiliation: Swiss Federal Institute for Environmental Science and Technology, EAWAG, Dübendorf.
authors.forename: A
authors.initials: A
authors.lastname: Driedger
authors.forename: E
authors.initials: E
authors.lastname: Staub
authors.forename: U
authors.initials: U
authors.lastname: Pinkernell
authors.forename: B
authors.initials: B
authors.lastname: Mariñas
authors.forename: W
authors.initials: W
authors.lastname: Köster
authors.forename: U
authors.initials: U
authors.lastname: Von Gunten
mesh_terms: D000465:Algorithms; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001412:Bacillus subtilis / Q000187:drug effects* / Q000502:physiology; D001959:Bromates / Q000378:metabolism* / Q000592:standards; D003080:Cold Temperature; D016785:Cryptosporidium parvum / Q000187:drug effects* / Q000502:physiology; D004202:Disinfectants / Q000494:pharmacology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010063:Ovum / Q000187:drug effects / Q000254:growth & development; D010083:Oxidants, Photochemical / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects / Q000254:growth & development; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D001959:Bromates; D004202:Disinfectants; D010083:Oxidants, Photochemical; D010126:Ozone; D000641:Ammonia