Industrial Cooling Tower Disinfection Treatment to Prevent Legionella spp.

Abstract

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.

Intracellular Behaviour of Three Legionella pneumophila Strains within Three Amoeba Strains, Including Willaertia magna C2c Maky

“…Moreover, these chemical biocides are dangerous to the environment, they degrade the installation systems, and they require the application of other products such as anti-corrosive agents [42,43]. Described by Iervolino, treatment with another oxidizing agent (H 2 O 2 /Ag) was inadequate for legionella control, and, instead, it caused a rapid increase of one logarithmic unit [44]. Chemical biocide action also is not completely efficient against biofilms and amoeba cysts that can provide protection against disinfection treatment [16,17,45].…”

Development and Demonstration of Membrane to Control Potential Pathogen (Legionella sp.) Associated With Cooling Towers

“…Various reports showed the abundant presence of pathogenic micro-organism such as L. pneumophila and Pseudomonas aeruginosa in the cooling towers (Wery et al, 2008;Iervolino et al, 2017;Paranjape et al, 2019).…”

Métodos de desinfección del agua y su implicación en la legionelosis

“…En el caso de Legionella pneumophila suele asociarse con otros microorganismos de los que en algunas ocasiones obtiene nutrientes orgánicos o protección (Richards, Von Dwingelo, Price, & Abu-Kwaik, 2013;Dietersdorfer, Cervero-Aragó, Sommer, Kirschner, & Walochnik, 2016), por lo que el control microbiológico es un elemento fundamental en la prevención de la legionelosis (Iervolino, Mancini, & Cristino, 2017;Ohno, Kato, Yamada, & Yamaguchi, 2003).…”