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Industrial Cooling Tower Disinfection Treatment to Prevent Legionella spp.

Department of Biological, Geological and Environmental Sciences, BiGeA, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy
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Int. J. Environ. Res. Public Health 2017, 14(10), 1125; https://doi.org/10.3390/ijerph14101125
Received: 28 July 2017 / Revised: 19 September 2017 / Accepted: 22 September 2017 / Published: 26 September 2017
The contamination of industrial cooling towers has been identified as one cause of legionellosis, but the real risk has been underestimated. Two different disinfection treatments were tested on Legionella colonization in an industrial Cooling Tower System (CTS). Environmental monitoring of Legionella, P. aeruginosa, and a heterotrophic plate count (HPC) at 36 °C was performed from June to October 2016. The disinfection procedures adopted were based on hydrogen peroxide (H2O2) and silver salts (Ag+), in addition to an anti-algal treatment, then using hyperclorination as a shock, and then continuous treatment by sodium hypochlorite (NaClO). L. pneumophila serogroup 8 was found at a concentration of 5.06 Log cfu/L after the CTS filling; a shock treatment performed by H2O2/Ag+ produced a rapid increase in contamination up to 6.14 Log cfu/L. The CTS activity was stopped and two subsequent shock treatments were performed using NaClO, followed by continuous hyperclorination. These procedures showed a significant decrease (p < 0.05) in Legionella concentration (1.77 Log cfu/L). The same trend was observed for P. aeruginosa (0.55 Log cfu/100 mL) and HPC (1.95 Log cfu/mL) at 36 °C. Environmental monitoring and the adoption of maintenance procedures, including anti-scale treatment, and physical, chemical, and microbiological control, ensure the good performance of a CTS, reducing the Legionella risk for public health. View Full-Text
Keywords: cooling tower system; disinfection treatments; microbiological parameters; Legionella spp. cooling tower system; disinfection treatments; microbiological parameters; Legionella spp.
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Iervolino, M.; Mancini, B.; Cristino, S. Industrial Cooling Tower Disinfection Treatment to Prevent Legionella spp.. Int. J. Environ. Res. Public Health 2017, 14, 1125.

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