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A dechlorinated drinking water distribution system simulator containing 15-year old unlined iron pipe was contaminated with Bacillus globigii spores. Bulk phase spore density decreased by 1.5-2.0 loglo 5 min after injection and declined by 1.8-3.4 [log.sub.10] after 4 d. Spores were detected on the iron pipe interior at 2 and 22 CFU/[cm.sup.2] after it was decontaminated and disassembled. These results support previous bench-scale studies that show that spores can persist on corroded surfaces in a drinking water environment. Key words: Bacillus, spores, biofilm, adhesion, iron, corrosion, drinking water, free chlorine. Un simulateur de systeme de distribution d'eau potable dechloree comportant un tuyau en fer non double et age de 15 ans a ete contamine par des spores de Bacillus globigii. La densite des spores dans la phase liquide volumique a diminue de 1,5 a 2,0 [log.sub.10] cinq minutes apres l'injecti on et a baisse de 1,8 a 3,4 loglo apres 4 jours. Les spores ont ete detectees a l'interieur du tuyau de fer a 2 et 22 CFU/[cm.sup.2] une fois qu'il a ete decontamine et demonte. Les resultats soutiennent les etudes anterieures a l'echelle du laboratoire qui montrent que les spores peuvent persister sur des surfaces corrodees dans un environnement d'eau potable. Mots-cles : Bacillus, spores, biofilm, adhesion, fer, corrosion, eau potable, chlore libre. [Traduit par la Redaction], Introduction Research studies examining the persistence of biological agents on drinking water distribution infrastructure have frequently been performed with bench-scale devices (Camper et al. 1996; Morin et al. 1996; Armon [...]

Efforts aimed at reducing pollutant loads from combined sewer overflows (CSOs) on the Muddy Creek receiving waters in Cincinnati, Ohio have been underway in recent years. This includes an investigation of the treatment performance of a flow-through wet weather treatment facility (WWTF) using off-line sedimentation tanks, fine screening and chemical disinfection (disinfection was inactive during this study). Calculations using hydrographs and water quality samples collected at the WWTF during rain events established the mass of biochemical oxygen demand [(BOD).sub.5], chemical oxygen demand, and total suspended solids (TSS) removed. Ten storm events sampled from January to September 2002 helped characterize pollutant removal efficiencies for flow-through treatment. Pollutant removal was classified into four components: flow to the wastewater treatment plant (WWTP), sedimentation, storage, and screening. Most pollutant removal was achieved through settling and storage in the treatment tanks, with removal efficiencies of 20-50% for BOD5 and 25-70% for TSS commonly observed. Owing to the high pollutant load in the early portion of the CSO hydrograph, first-flush containment, or capturing and conveying the early portion of the runoff event to the WWTP, was the most efficient treatment method for every storm investigated. CE Database subject headings: Combined sewer overflow; Sedimentation tanks; Storage tanks; Water pollution; Wastewater management; Ohio; Case reports.

Persistence of Bacillus atrophaeus subsp. globigii spores on corroded iron coupons in drinking water is analyzed by using a biofilm annular reactor. The studies have shown that Bacillus atrophaeus subsp. globigii spores are capable of persisting for an extended time in the presence of high levels of free chlorine.

Building water systems promote the regrowth and survival of opportunistic pathogens, such as Legionella pneumophila, especially within biofilms, where most drinking water microbes reside. However, compared to their planktonic form, disinfection efficacy for the biofilm-associated forms of water-based pathogens is unclear. The aim of this study was to determine the effectiveness of free chlorine and monochloramine in the inactivation of biofilm-associated L. pneumophila strain Philadelphia-1 serogroup 1 (Lp). Mature (1.5-2 y old) drinking water biofilms were developed on copper (Cu) and polyvinylchloride (PVC) slides within biofilm annular reactors, then colonized with Lp at approximately 4 log10 CFU cm-2 and exposed to 2 mg L-1 of free chlorine or monochloramine. Ct (disinfectant concentration x time, expressed as mg min L-1) inactivation values for 2-, 3-, and 4-log10 reduction of planktonic and biofilm Lp were determined. For planktonic Lp, free chlorine was more effective at inactivation compared to monochloramine treatment and for biofilm-associated Lp, monochloramine was more effective on Cu biofilms, while free chlorine was more effective on PVC biofilms. In contrast to monochloramine, free chlorine treatment of Cu and PVC biofilms, negatively impacted Lp 16S rRNA gene transcript levels, and may act synergistically with Cu surfaces to further reduce transcript levels. Moreover, Lp cells shed from biofilms into the bulk water, were more resistant to disinfection compared to prepared planktonic Lp cells. Results from this study indicate that biofilm association, disinfectant type, and substratum play an important role in the survival of Legionella pneumophila in building water systems. [ABSTRACT FROM AUTHOR]