1. Cooling Tower Maintenance Legionella Awareness
4th Installment

2. CTM/Ashland Presentations
Legionella Awareness – 2003
Filtration of Cooling Waters – 2005
Legionella Risk Management – 2006
Legionella Proactive Protocol – 2008
Legionella Refresher
Literature References

3. Legionella Proactive Protocol 2008
Introduction/Refresher
Systems that may Harbor Legionella and What to Do
Risk Category
Legionella Testing Requirements
Frequency of Cleaning/Disinfection
Action Levels and Associated Response and Cleaning Steps
Cooling Tower Design Best Practice
Maintenance Considerations

4. Legionella Refresher 2011
Legionella Sources
Legionella Control
Planning and Record Keeping

5. Legionella Sources

6. Legionella Bacteria Source of Legionella Conditions for growth
Pervasive organism
Soil derived
Conditions for growth
68 - 122 F (20 - 50 C)
pH 6-8
Stagnant waters
A nutrient source
Biofilms, organics
Sediments, deposits

7. Factors Determining the Risk of Contracting the Disease
A source of Legionella
Favorable growth conditions
Aqueous aerosols less than or equal to 5 microns
Sufficient organisms to cause infection
Susceptible individual

8. Systems Promoting Growth
Cooling towers
Evaporative condensers
Hot and cold water systems
Taps and showerheads
Humidifiers and air washers
Spa and whirlpool baths
Decorative fountains
All systems noted are at a potential risk for transmitting Legionella bacteria because they have the potential to meet all the criteria noted in slide # 5, i.e.,
A source of Legionella organism
Optimum conditions for growth
Aqueous aerosol for transmission
Sufficient organisms to cause infection
Transmission to susceptible individual

9. Field Study on Biofilm Growth
Phase
Time
Colonization
15 Minutes
Growth Detection
2 Days
Biofilm Formation
(Exopolymer/ Minimum Biofouling)
5 Days
Maximum Biofilm Growth
(8 – 10 Cells Thick)
14 Days
Fully Mature Biofilm Matrix
31 – 40 Days
It is the Legionella harbored in biofilms that are of most concern as they be in the virlent state whithin a host cell (higher life forms such as protozoan, omeba etc) and amplify in numbers and be protected. So biofilm control is most important.

10. Cyclic Operation and Biofilms
AOC supports bofilm growth
Flow and AOC supply stopped results in biofilm starvation and detachment
- 90% in 24 hours
- 80% in 12 hours
- 60% in 10 hours
- 40% in 8 hours
Continuous flow without AOC achieves 90% biofilm detachment in 3 days
Taken from “Hypothesis for the Role of Nutrient Starvation in Biofilm Detachment” Montana State University, Applied & Enviormental Microbiology, Dec
2004, pages 7418 to 7425.
21 days to develop a good biofilm, 10^9 CFU/cm^2, 300 micro meters thick
Food (AOC) is glucose.
AOC is more important than the bulk water bacterial count (ie CFU/ml), <10ppb AOC little to no growth, < 20ppb AOC the target to avoid excessive biofilms.
2 week biofilm growth is about 1.4 to 2.7 X 10^5 CFU/cm^2

11. Effects of Cooling System Dynamics – cfu/ml Same Day Comparative Samples (Example System Treated with Continuous Oxidant and Slug Feed of Glutaraldehyde Once Per Week)
Aerobic Bacteria
Fungi
Anaerobic Bacteria
Higher
Life Forms
Flowing Bulk Water Basin Chip Scale
<10
1600 10
1,000,000 No
Yes
Basin Sludge
3,500,000 20
Dead Head (off) Plate/Frame XER
400
10,000
Slip Stream
By-pass (10%) Plate/Frame

12. Legionella Control

13. Microbiological Control Capability
Efficacious biocides selection
Biodispersant supplement for biofilm
Effective application for required concentration and contact time
System dynamics (ART, T½) and volume
Dedicated automated feed of microbiocides
Feedback control Loop (ORP, self verifying feed pumps)
Pre-conditioning/sterilization
Preseason start-up
Idle restarts
Sterilization/hyper chlorination at the summer peak
End of season shutdown

14. Microbiological Control Additives of Choice
Oxidation
Bleach (CSW 20)
Sodium Bromide/Bleach (Drewbrom)
BCDMH (Biosperse 261T)
Chlorine Dioxide
Non Oxidants
Glutaraldehyde 1º (Biosperse 254/255)
Isothiazolin 2º (Biosperse 250)
Biodispersants
Nonionic Surfactants (Drewsperse 739)
Protein cross linking/cationic surfactant blend (Performax 405)
Anionic surfactants (Drewsperse 7211)
The use of Ozone, Ultra Violet Light and or Copper/Silver Producing Electrolysis in combination with a biocide are also acceptable. Their use alone, without chemicals is not effective in large water systems accept potable water systems within the building. Care must be taken with the use of Copper/Silver applications in systems where carbon steel metals are also used, otherwise localized galvanic corrosion maybe incurred by the carbon steel components.

15. Legionella Control with Non-Oxidizing Biocides
Chemical Compound
Active Concentration mg/ℓ
Contact Time
Glutaraldehyde
1 Hour
Isothiazolin
6 Hours
2 Bromo-2-Nitro Propane-1,3, diol (BNPD) 25
400
24 Hours
60 Minutes
Dithiocarbamates
Di-bromo-nitrilo-propionamide (DBNPA)
4 - 8
2 Hours
Note: System potential contaminants and operational pH must be checked for compatibility with the non-oxidizing biocide
The amount of biocide added via slug feeding must be higher than noted above in order to attain the residual noted above at the end of the required contact time.

16. Continuous Oxidant Feed Protocol
Continuous feed for chlorine, bromine, BCDMH or stabilized bromine
Dosage:
Recommended FAH and/or equivalent mV ORP with a minimum requirement of a measurable residual FAH
For higher risk systems increase FAH residual as needed to control CFU level and biofilm
Feed a supplemental organic biocide*
Recommend biocide be glutaraldehyde or an alternate biocide fed with biodispersant
Feed once per week or as needed to control biofilm
This slide highlights biocide requirements when continuous oxidant feed option is applied.
Glutaraldehyde is recommended due to its excellent ability to strip biofilm as well as compatibility with oxidizing microbiocides. In the event glutaraldehyde can not be applied at a facility, alternative organic biocides can be applied. Selection is dependent on Relative Population Density (RPD) study results.
ORP is oxidation-reduction potential, the measure of a water’s oxidation energy.
*Alternative choices of non-oxidizing biocide should be based on Relative Population Density (RPD) lab results

17.  Intermittent Oxidant Feed Protocol
Chlorine, bromine, BCDMH or stabilized bromine
Minimum dosage: Hold FAH and/or equivalent mV ORP for a minimum of 2 hours each day
Feed alternating supplemental organic biocides*
Recommend one biocide be glutaraldehyde or an alternate biocide fed with biodispersant
Feed an additional compatible organic biocide*
Alternate feed once per week
*Alternative choices of non-oxidizing biocide should be based on RPD results

18. Oxidant Feedrate

19. Legionella Testing Requirements

20. Action Levels Immediate response to positive test results
On-line treatment requires a minimum of 14 days to produce results
Unrealistic a system could be totally Legionella free

21. Direct Testing of Legionella
Frequency Consideration
Prior to peak summer sterilization (i.e. beginning/mid August) for seasonally operated HVAC or after a sterilization.
After cleaning of a confirmed cooling tower sourced outbreak
If a confirmed outbreak has occurred in the area (≤3 km minimum)
Three times per year of 24/7 Industrial process cooling systems of higher risk noted earlier

22. Suggested Legionella Remedial Action Criteria
Legionalla
(CFU/ml)
Cooling/Tower
Evaporative Condenser
Potable Water
Humidifier/Fogger
Detectable;<1 1 2 3
1-9 4
10-99 5
>1000
Actions –
Review Maintenance
Follow-up Analysis and Implement Action 1
Implement Action 2, Conduct review of Direct and Indirect Bio aerosol Contact of Occupants and Health Risk Status of Occupants May Lead to Increased Biocide Applications or Online Clean
Implement Action 3, Cleaning/Biocide Improvement is Indicated
Immediate Biocide Improvement and Cleaning is Indicated Levels have a Potential for Outbreak
© 1998, PathCon Laboratories, Pathogen Control Associates Inc.
Note the action criteria; the order of highest to lowest potential risk is Humidifer/Fogger, then the potable water, then the cooling water.

23. Frequency of Cleaning/Disinfection

24. Frequency of Cleaning/Disinfection
Immediately prior to new system being commissioned
If the system has been out of use for one month or longer
If the system has been modified, entered or disturbed in such a way to lead to contamination
If the cleanliness of the system is in any doubt
If microbiological monitoring indicates there is a problem
At least twice a year

25. Frequency of Cleaning/Disinfection
Preconditioning/Disinfection
End of Operating Season
2 per Year Minimum for 24/7 Systems (4)
Disinfection Only
At Peak Seasonal Demand
Occurrence of Outbreaks in the Area
Upon System Restarts of ≤ 4 weeks Idleness (≥ 3 Days?)’
Idle System of 1 Month or More to be Drained

26. Sterilization Only Frequency
During restart of idle/stagnant towers, condensers, heat exchangers
Seasonal restart of HVAC system, which was preconditioned and sterilized the end of the previous season
Peak of summer cooling demand
(i.e. beginning of August).
Known outbreaks in the area
Biological dip slide counts exceed 105 – 106 CFU/ml. Visible slime (i.e. biofilm) present.

27. Planning and Record Keeping

28. Total System Approach: Five Areas of Activity and Performance
 Comprehensive system assessment
 Intensive microbiological treatment program
 Sterilization and cleaning
 Monitoring and control
Documentation
All Information is Available in Previous Presentations 03, 06, 08
Contact CTM or AHWT for the presentations and additional information.

29.  System Assessment System survey
In-depth survey of system mechanical layout and operating conditions
Utilizes established protocol, ex BSRIA- Building Services Research Institute Assoc. (UK)
Identify, evaluate and rank specific factors associated with potential for microbiological growth and Legionella
Mechanical and chemical
Determine risk minimization action plans
A formal system assessment is the first component of our Best Practices program and is an essential activity for Legionella risk management.
The system assessment is a “fee for service” survey that fully reviews mechanical, environmental, operational, and chemical treatment program parameters and evaluates the factors associated with the potential for microbiological growth and Legionella. The system survey evaluates the entire system in terms of critical factors and identifies mechanical and operational practices that should be modified to enhance system cleanliness.
The system survey follows an established, detailed protocol that is based on our decades of experiences in England (UK), using their regulated Approved Code of Practices (ACOP) guidelines and Australia and New Zealand where risk management is mandatory and regulated. In addition to global experiences, Drew Industrial’s Legionella risk management program is based on recommendations by CTI, ASHRAE, CDC, OSHA, and others.
The outcome of this assessment is a plan to minimize overall microbiological growth, minimize aerosol production and distribution from water systems, and recommendations to improve overall system cleanliness. Implementing the plan reduces the opportunity for Legionella growth and spread.
Drew Industrial can perform system assessments using trained internal resources or can use outside experts to perform these surveys and risk assessments. (Contact Joanne Kuchinski in Boonton for more information.)

30. Documentation Why Document?
When a pneumonia outbreak occurs in a facility it allows for:
Speed in identifying the source for eradication purposes, removing a potential and continual threat. After all it may not be cooling system derived.
Clinical micro biologists and physicians to select appropriate antibiotics, dosages and monitor the progress without the presence of further stressors.

31. Documentation To name a few:
Simplified line drawing of the cooling system and all equipment, dead legs cross over lines, chemical feed points/lines/control, system volume, recirculation make-up and blowdown rates
Key water test results/date
Chlorides or conductivity for cycles of concentration assessment
Make-up, blowdown water meter readings
FAH and/or ORP for Halogen concentration
Biological Tests – CFU/ml; CFU/cm2
Start, end and expiry dates of dip slide lots for bio testing

32. Documentation To name a few: Chemical pump and timer settings
Biocide usage
Start-up/shutdown and other application logs of preconditioning/sterilization and sterilization only
Inspection/observations for slimes, muds, algae in cooling tower and on coupons and what was done to improve
Contingency plans procedures, and results/check offs when performed.

33. Influence Risk Associated With Legionella

34. Survey of Process Risk HIGH LOW Humididifer/Fogger
Aerosol Producing Process
Misters, Atomizers
Air Washers
Decorative Fountains and Waterfalls
Whirl Pools
Hot Tubs
Shower Heads
Potable Water Hot/cold
Cooling Towers/ Evaporative Condensers Risk increases with Location (i.e. Grounds Levels, Near Air Intakes/Windows), Local Ground Cover, Air Contamination/ Proximity to Exhaust See C.T.I. Design and Maintenance Consideration
Sludge/Settled Solids
>⅛″ - ¼″
Non-Visible
Temperature
35ºC (95ºF)
To 46ºC (115ºF)
<20ºC (68ºF)
>50ºC (124ºF)
Biological Activity
>104 CFU/ml
>105 CFU/cm2
Presence of Higher life forms (OMEBA, PROTOZOA, ALGAE, MOLD, FUNGUS).
≤103 CFU/ml
≤104 CFU/cm2
No Higher Life Forms

35. Monitoring and Inspection
Inspection for visible slime or sludge's
Decks
Mist eliminators
Fill
Sumps
Corrosion or biofilm coupons

36. Biofilms Biofilms Don’t Just Harbour Legionella, They:
Restrict Air Flow
Restrict Water Flow
Reduce Heat Transfer
Reduce Heat Rejection
Induce Localized Corrosion
Biological Control
Higher Life Forms – None
Bacteria CFU/ml <104, > 105 Do something
Bacteria CFU/cm2 <105, >106 Do something

37. Preventive Action Use your Biocides in a Prudent Manner And Remember
Sterility Does Not Exist Except in Higher Life Forms