title: Disinfection of bacterial biofilms in pilot-scale cooling tower systems.
abstract: The impact of continuous chlorination and periodic glutaraldehyde treatment on planktonic and biofilm microbial communities was evaluated in pilot-scale cooling towers operated continuously for 3 months. The system was operated at a flow rate of 10,080 l day(-1). Experiments were performed with a well-defined microbial consortium containing three heterotrophic bacteria: Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. The persistence of each species was monitored in the recirculating cooling water loop and in biofilms on steel and PVC coupons in the cooling tower basin. The observed bacterial colonization in cooling towers did not follow trends in growth rates observed under batch conditions and, instead, reflected differences in the ability of each organism to remain attached and form biofilms under the high-through flow conditions in cooling towers. Flavobacterium was the dominant organism in the community, while P. aeruginosa and K. pneumoniae did not attach well to either PVC or steel coupons in cooling towers and were not able to persist in biofilms. As a result, the much greater ability of Flavobacterium to adhere to surfaces protected it from disinfection, whereas P. aeruginosa and K. pneumoniae were subject to rapid disinfection in the planktonic state.
authors.affiliation: Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Tadas
authors.initials: T
authors.lastname: Sileika
authors.forename: Richard
authors.initials: R
authors.lastname: Warta
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Cianciotto
authors.forename: Aaron I
authors.initials: AI
authors.lastname: Packman
mesh_terms: D000389:Air Conditioning; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002713:Chlorine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods*; D005417:Flavobacterium / Q000187:drug effects / Q000254:growth & development; D005976:Glutaral / Q000494:pharmacology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000254:growth & development; D059013:Microbial Consortia / Q000187:drug effects / Q000502:physiology; D010865:Pilot Projects; D010933:Plankton / Q000187:drug effects / Q000254:growth & development; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D013232:Steel; D014871:Water Microbiology
chemical_list: D013232:Steel; D002713:Chlorine; D005976:Glutaral