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Legionella and Cooling Towers

Cooling towers or heat rejection devices are used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to reject process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature.

Common applications include cooling the circulating water used in oil refineries, chemical plants, power plants and building cooling.

Environmental Hazards

Legionella have been known for some time to live within amoebae in the natural environment. Legionella species are the causative agent of the human Legionnaires' disease and the lesser form, Pontiac fever. Legionella transmission is via aerosols—the inhalation of mist droplets containing the bacteria.

According to recent research The Journal of Infectious Diseases provides evidence that Legionella pneumophilia, the causative agent of Legionnaires disease, can travel at least 6 km from its source by airborne spread.

Temperature Effects as a means of Control

At 70 to 80 °C (158 to 176 °F) - Disinfection range
At 66 °C (151 °F) – Legionella die within 2 minutes
At 60 °C (140 °F) – Legionella die within 32 minutes
At 55 °C (131 °F) – Legionella die within 5 to 6 hours
At 50 to 55 °C (122 to 131 °F) - Survive but do not multiply
At 20 to 50 °C (68 to 122 °F)- Legionella growth range
At 35 to 46 °C (95 to 115 °F) - Ideal growth range
At Below 20 °C (68 °F) – Legionella can survive but are dormant

Alternative Treatments

Chemical Treatment
1. In the Short term Chlorine Cl2, must be repeated every 3 to 5 weeks, corrosion issues
2. In the Long term Chlorine Cl2, can take up to 17 months for system saturation

Non-Chemical Treatment
1. In the Short term Thermal eradication must be repeated every 3 to 5 weeks
2. In the Long term Industrial size copper silver ionisation (Ionization) technology

All of the above methods are time consuming and expensive with no absolute guarantee of success

The Solution from TRDuk

TRDuk use a patented product to form an Oxidative Process Hygiene System based on in-situ Chlorine Dioxide generation. Our solution is designed to be competitive with other Oxidative regimes, e.g., Cl2, Bromination and O3 as it is a unique delivery system for Chlorine Dioxide solution production. The ClO2 being the active component enabling disinfection is generated at 99.99% pure ClO2. The residuals are sodium sulphate (Na2SO4) and sodium chloride (NaCl)

Our product delivers a 5 Log reduction within 60 seconds at a concentration of average <50% than other disinfectants thus we can replace Chlorine at a 5-1 ratio thus preventing corrosion issues and is more cost effective saving you time and money.

The result - Complete eradication of all known micro-bacterial material

Contact Info
TRDuk coverage area for
TRDuk Limited


Phone: 0208 4412777

Head Office:
27 York Road,
New Barnet,

Regional Office
20 Daneland,
East Barnet,