Efficacy of Bromochlorodimethylhydantoin against Legionella pneumophila in Industrial Cooling Water Systems

摘要

Cooling towers provide an ideal environment for the growth of Legionella pneumophila. Guidelines published by industry groups and governmental bodies recommend the use of oxidizing biocides for the control of L. pneumophila populations. We report here the results of a literature review on the biocidal activity of the oxidizing biocide bromochlorodimethyl- hydantoin (BCDMH) against L. pneumophila. BCDMH achieved >99.9 percent reduction in viability within 10 minutes of planktonic, pure culture L. pneumophila with 1 ppm free residual chlorine in a typical cooling water. Studies in dynamic laboratory systems inoculated with a natural microbial flora showed that BCDMH was equally effective against planktonic and sessile (biofilm) populations of L. pneumophila. Several excellent field efficacy studies have been conducted with BCDMH. These studies indicate that the continuous application of BCDMH to achieve 1-2 ppm free residual chlorine was effective at reducing viable L. pneumophila counts to undetectable levels in the recirculating water. Total bacteria counts were also reduced in all cases by the BCDMH treatment.