Contamination of industrial cooling towers has been identified as the cause of sporadic cases and outbreaks of legionellosis. The epidemiological data showed as the risk of Legionella infection coming from cooling tower is underestimated. The aim of the study was to assess the effectiveness of different disinfection treatments on Legionella colonization, performed within an industrial Cooling Tower System (CTS) starting from opening to closing season. Materials/Methods: Cold water samples were collected monthly from May to October 2016, during an environmental monitoring of industrial CTS nearby Bologna, Italy. Legionella culture was carried out according to ISO11731-1998. Two disinfection treatments were subsequently performed in relation to microbiological levels found. The first performed for 7 days based on hydrogen peroxide (H2O2 )/silver salts (Ag+) at shock concentration of 100 mg L-1 in synergic association to an antialgal treatment and the second performed by sodium hypochlorite at 50 mg L-1 for 15 days. 1 / 2 inserimenti Results: Ourdata show the presence of L. pneumophila SG8 at a level of 5,06 log10 UFC L -1 after the water CTS filling, that required a shock treatment performed for one week by H2O2 /Ag+ . This treatmentincreases a Legionella contamination level until 6,14 log10 UFC L-1 . These data required a stop of CTS activity, washing of circuit by peracetic acid and two subsequently shock hyperchlorination. After 15 days we observed a decrease of Legionella level to 1,90 log10 UFC L-1. maintained for all tested period. Conclusions: Our data confirm the role of routinely environmental monitoring before and during CTS operating conditions. The introduction of preliminary procedures before the disinfection treatment as anti-scale treatment, washing of CTS, measures of physical-chemicalparameters and control of microbiological contaminants, permit a good performance of CTS, reducing the risk for the stakeholders and public health.
Iervolino M., M.B. (2017). Industrial cooling tower, treatment and control measures to prevent Legionella spp..
Industrial cooling tower, treatment and control measures to prevent Legionella spp.
Cristino S.
Writing – Original Draft Preparation
2017
Abstract
Contamination of industrial cooling towers has been identified as the cause of sporadic cases and outbreaks of legionellosis. The epidemiological data showed as the risk of Legionella infection coming from cooling tower is underestimated. The aim of the study was to assess the effectiveness of different disinfection treatments on Legionella colonization, performed within an industrial Cooling Tower System (CTS) starting from opening to closing season. Materials/Methods: Cold water samples were collected monthly from May to October 2016, during an environmental monitoring of industrial CTS nearby Bologna, Italy. Legionella culture was carried out according to ISO11731-1998. Two disinfection treatments were subsequently performed in relation to microbiological levels found. The first performed for 7 days based on hydrogen peroxide (H2O2 )/silver salts (Ag+) at shock concentration of 100 mg L-1 in synergic association to an antialgal treatment and the second performed by sodium hypochlorite at 50 mg L-1 for 15 days. 1 / 2 inserimenti Results: Ourdata show the presence of L. pneumophila SG8 at a level of 5,06 log10 UFC L -1 after the water CTS filling, that required a shock treatment performed for one week by H2O2 /Ag+ . This treatmentincreases a Legionella contamination level until 6,14 log10 UFC L-1 . These data required a stop of CTS activity, washing of circuit by peracetic acid and two subsequently shock hyperchlorination. After 15 days we observed a decrease of Legionella level to 1,90 log10 UFC L-1. maintained for all tested period. Conclusions: Our data confirm the role of routinely environmental monitoring before and during CTS operating conditions. The introduction of preliminary procedures before the disinfection treatment as anti-scale treatment, washing of CTS, measures of physical-chemicalparameters and control of microbiological contaminants, permit a good performance of CTS, reducing the risk for the stakeholders and public health.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
