When Legionella pneumophila is detected at 1,400 CFU/mL in a cooling tower, what is the best sequence of procedures for disinfection?

The sequence of procedures for disinfection when Legionella pneumophila is detected at 1,400 CFU/mL in a cooling tower is critical to ensure effective removal and prevention of the bacteria. Starting with hyperchlorination is essential because this step introduces a high concentration of chlorine to the system, which serves to kill Legionella bacteria that may be present in the water before any physical cleaning is performed. This helps to ensure that the disinfection process is maximally effective.

Following hyperchlorination, draining the system is important to remove the treated water that may still contain contaminants. By draining the system after the initial chemical disinfection, you are ensuring that the harmful bacteria are flushed out of the cooling tower.

The next steps, power washing and brushing, focus on physically removing any biofilm or sediment that may harbor bacteria. These physical cleaning measures are most effective when the system is empty and can offer thorough access to all surfaces without the interference of standing water.

This combination of chemical and physical disinfection steps in the correct order helps ensure that Legionella is effectively eradicated from the cooling tower, minimizing health risks associated with aerosolization of the bacteria. This systematic approach to disinfection is crucial in managing and controlling Legionella outbreaks in water systems.