Alkaline approach to treating cooling towers for control of Legionella pneumophila

Journal Article · Sat Aug 01 04:00:00 EDT 1987 · Appl. Environ. Microbiol.; (United States)

OSTI ID:5558917

States, S J; Conley, L F; Towner, S G; Wolford, R S; Stephenson, T E; McNamara, M; Wadowsky, R M; Yee, R B

Earlier field and laboratory studies have shown that Legionella species survive and multiply in the pH range 5.5 to 9.2. Additionally, the technical feasibility of operating cooling towers at elevated alkalinities and pH has previously been documented by published guidelines. The guidelines indicate that these conditions facilitate corrosion control and favor chlorine persistence which enhances the effectiveness of continuous chlorination in biofouling control. This information suggest that control of Legionella species in cooling towers can be accomplished by operating the towers under alkaline conditions. To test this possibility, we collected water samples over a period of months from a hospital cooling tower. The samples were analyzed for a variety of chemical parameters. Subsamples were pasteurized and inoculated with non-agar-passaged Legionella pneumophila which had been maintained in tap water. Correlation of subsequent Legionella growth with corresponding pH and alkalinity values revealed statistically significant inverse associations. These data support the hypothesis that operating cooling towers outside of the optimal conditions for Legionella growth (e.g., at elevated alkalinities and a pH greater than 9) may be a useful approach to controlling growth in this habitat.

• Research Organization: City of Pittsburgh Water Dept., PA
• OSTI ID: 5558917
• Journal Information: Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 53:8; ISSN AEMID
• Country of Publication: United States
• Language: English

Related Subjects

552000* -- Public Health
99 GENERAL AND MISCELLANEOUS
BACTERIA
BUILDINGS
COOLING TOWERS
GROWTH
HABITAT
HOSPITALS
LEGIONELLA PNEUMOPHILA
MECHANICAL STRUCTURES
MEDICAL ESTABLISHMENTS
MICROORGANISMS
PH VALUE
SURVIVAL CURVES
TOWERS