Presentation is loading. Please wait.

Presentation is loading. Please wait.

Legionnaires' Disease in Cooling Towers vs Ozone

Similar presentations


Presentation on theme: "Legionnaires' Disease in Cooling Towers vs Ozone"— Presentation transcript:

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


Download ppt "Legionnaires' Disease in Cooling Towers vs Ozone"

Similar presentations


Ads by Google