1. Legionnaires' Disease in Cooling Towers vs Ozone

2. Legionnaires' Disease
Most recognized form of infectious disease known to be associated with cooling towers
Also known as Pontiac Fever (though PF is actually a little different)
A form of atypical pneumonia caused by any species of Gram- negative aerobic bacteria belonging to the genus Legionella
Over 90% of cases of Legionnaire’s Disease are caused by Legionella pneumophila
Over 20 subgroups of the bacteria allow genetic tracing back to source

3. Legionnaires' Disease
Legionella needs areas to grow such as sludge and biofilm
Primarily they use protozoans as hosts

4. Legionnaires' Disease
As biofilm grows, it sloughs off into the cooling water releasing
bacteria, including the Legionella pneumophila
protozoan hosts which eventually burst to release the Legionella

5. Legionnaires' Disease
According the World Health Organization, their unique characteristic is the ability to multiply inside protozoa
Once found, the system must be disinfected (Wisconsin Protocol or ASHRAE 188P)
WHO further states that reappearance will be preceded by an increase in Heterotrophic Bacteria above 100 CFU (Colony Forming Units)

6. How Prevalent is this Bacteria
Found in Cooling Towers – mainly due to towers’ environment that is conducive to biological growth in general
Highly oxygenated
Warm and moist
Prevalent food sources
Pervasiveness of other bacteria that can act as hosts
Also found in rivers, ponds, puddles, and drinking water

7. How Prevalent is this Bacteria
Found in Hot Tubs (1990s case traced to a demo hot tub at a big box store)
Found in Condensate drip pans (original outbreak that brought it to our attention)
Found in shower heads and faucets in hospitals
Found in potable hot water (particularly where there is a concern for scalding – water temperature kept lower)
Recently contracted by people walking past cooling towers

8. Neither really, but is should be taken seriously
Dangerous?
Ebola or
Common Cold!
Neither really, but is should be taken seriously

9. How Dangerous is Legionellosis
As stated earlier, the bacteria is everywhere, but it must be aspirated and inhaled to infect
Must be in water droplets
Not a spore, cannot survive outside of moist environment
Cannot infect through drinking water containing the bacteria
Cannot infect through skin contact (washing) even if exposed to a cut
Cannot be transmitted from infected person to another person
Bacteria infiltrates lungs where it is eaten (Phagocytized) by natural Antibodies
Reproduces inside the Antibody then explodes out thereby infecting other cells
Infected person generally has a compromised immune system

10. Legionellosis Cycle

11. Defense – be Proactive not Reactive
Investigate/manage equipment placement
Avoid high traffic areas (personnel), walkways, playgrounds, outside meeting area
Avoid proximity to building air intakes
Good housekeeping
Keep tower free of debris (screens on fill, position away from trees)
Keep sumps clean and free of mud
Employ filtration system if necessary
ASHRAE 188P
Complex, but complete
Mainly addresses ingress points and potable water

12. Defense – be Proactive not Reactive
Standard traditional treatment program
Dispersants, penetrants, and inhibitors
Dual alternating biocide program
Good monitoring
This will minimize risk
Continuous treatment
CDC recommends continual treatment over dose biocide treatment
Chlorine, Chlorine Dioxide, or Ozone
Ozone
Most effective treatment based on C/T (concentration/time) of disenfectant

13. Ozone Ozone is continuous treatment (as recommended by the CDC)
Ozone provides the best C/T (concentration/time) value for disinfection
Having been used for drinking water for over 100 years, Ozone has proven superior at reducing or eliminating biofilm
Ozone is a proven antimicrobial and is approved by the EPA in determining C/T values in disinfecting drinking water and is superior to other potable water disinfectants

14. Ozone
Through cold combustion Ozone destroys all bacteria it contacts, disrupting the cell wall
This makes it impossible for any bacteria to develop an immunity to ozone as they often do with traditional biocides
O3 as low as 0.3 mg/L can achieve a 5 log10 reaction in as little as 20 minutes (C/T value)
Ozone maintains Heterotrophic bacterial growth below 100 CFU – Remember what WHO said about 100 CFU (Industry standard for ordinary treatment program is 10,000 CFU)

15. What is Ozone? 03 - an unstable form of oxygen with three atoms
Powerful oxidizing biocide
500% more effective than chlorine
Short life in evaporative cooling water (around 15 minutes)
Environmentally Safe - breaks down to oxygen
Oxygen fed Corona discharge is most effective and controllable method for on-site generation