title: Decontamination of Bacillus spores adhered to iron and cement-mortar drinking water infrastructure in a model system using disinfectants.
abstract: Decontamination of Bacillus spores adhered to common drinking water infrastructure surfaces was evaluated using a variety of disinfectants. Corroded iron and cement-mortar lined iron represented the infrastructure surfaces, and were conditioned in a 23 m long, 15 cm diameter (75 ft long, 6 in diameter) pilot-scale drinking water distribution pipe system. Decontamination was evaluated using increased water velocity (flushing) alone at 0.5 m s-1(1.7 ft s-1), as well as free chlorine (5 and 25 mg L-1), monochloramine (25 mg L-1), chlorine dioxide (5 and 25 mg L-1), ozone (2.0 mg L-1), peracetic acid 25 mg L-1) and acidified nitrite (0.1 mol L-1at pH 2 and 3), all followed by flushing at 0.3 m s-1(1 ft s-1). Flushing alone reduced the adhered spores by 0.5 and 2.0 log10from iron and cement-mortar, respectively. Log10reduction on corroded iron pipe wall coupons ranged from 1.0 to 2.9 at respective chlorine dioxide concentrations of 5 and 25 mg L-1, although spores were undetectable on the iron surface during disinfection at 25 mg L-1. Acidified nitrite (pH 2, 0.1 mol L-1) yielded no detectable spores on the iron surface during the flushing phase after disinfection. Chlorine dioxide was the best performing disinfectant with >3.0 log10removal from cement-mortar at 5 and 25 mg L-1. The data show that free chlorine, monochloramine, ozone and chlorine dioxide followed by flushing can reduce adhered spores by > 3.0 log10on cement-mortar.
authors.affiliation: U.S. Environmental Protection Agency, National Homeland Security Research Center, Water Infrastructure Protection Division, 26 W. Martin Luther King Dr. (MS NG-16), Cincinnati, OH 45268, United States. Electronic address: szabo.jeff@epa.gov.
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Szabo
authors.affiliation: CB&I Federal Services, LLC., 1600 Gest St., Cincinnati, OH 45204, United States. Electronic address: greg.meiners@CBIFederalServices.com.
authors.forename: Greg
authors.initials: G
authors.lastname: Meiners
authors.affiliation: CB&I Federal Services, LLC., 1600 Gest St., Cincinnati, OH 45204, United States. Electronic address: heckman.lee@epa.gov.
authors.forename: Lee
authors.initials: L
authors.lastname: Heckman
authors.affiliation: U.S. Environmental Protection Agency, National Homeland Security Research Center, Water Infrastructure Protection Division, 26 W. Martin Luther King Dr. (MS NG-16), Cincinnati, OH 45268, United States. Electronic address: rice.gene@epa.gov.
authors.forename: Eugene W
authors.initials: EW
authors.lastname: Rice
authors.affiliation: U.S. Environmental Protection Agency, National Homeland Security Research Center, Water Infrastructure Protection Division, 26 W. Martin Luther King Dr. (MS NG-16), Cincinnati, OH 45268, United States. Electronic address: hall.john@epa.gov.
authors.forename: John
authors.initials: J
authors.lastname: Hall
mesh_terms: D001407:Bacillus / Q000187:drug effects* / Q000254:growth & development; D018441:Biofilms / Q000187:drug effects; D002700:Chloramines / Q000494:pharmacology; D017606:Chlorine Compounds / Q000494:pharmacology; D015169:Colony Count, Microbial; D003666:Decontamination / Q000379:methods*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D060766:Drinking Water / Q000382:microbiology*; D007501:Iron; D010087:Oxides / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology; D010463:Peracetic Acid / Q000494:pharmacology; D013171:Spores, Bacterial / Q000187:drug effects* / Q000254:growth & development
chemical_list: D002700:Chloramines; D017606:Chlorine Compounds; D004202:Disinfectants; D060766:Drinking Water; D010087:Oxides; D010126:Ozone; C025109:chlorine dioxide; D007501:Iron; D010463:Peracetic Acid; C030816:chloramine
keywords: Bacillus; Decontamination; Disinfection; Drinking water; Spores