Disinfection of bacterial biofilms in pilot-scale cooling tower systems

Yang Liu, Wei Zhang, Tadas Sileika, Richard Warta, Nicholas P. Cianciotto, Aaron I. Packman

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

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 1 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.

Original languageEnglish (US)
Pages (from-to)393-402
Number of pages10
JournalBiofouling
Volume27
Issue number4
DOIs
StatePublished - Apr 2011

Funding

This publication was made possible by Grant Number 5K25AI062977 to A.I.P. from the National Institute of Allergy and Infectious Disease (NIAID) at the National Institutes of Health. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIAID. Construction of the cooling tower experimental system was supported by a contract from the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) awarded to N.P.C. and A.I.P. The authors thank Barry Fields for providing the bacterial strains used in the experiments, and Laura MacDonald and Kylie Ruehlow for their assistance in monitoring the performance of the cooling tower system.

Keywords

  • Bacterial biofilms
  • Chlorination
  • Disinfection
  • Glutaraldehyde
  • Microbial community
  • Pilot-scale cooling towers

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Water Science and Technology
  • Aquatic Science

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