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Cooling Tower Maintenance Legionella Awareness

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Presentation on theme: "Cooling Tower Maintenance Legionella Awareness"— Presentation transcript:

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 Implications of the Need for Biocide Improvements
Action Days After Action 2 Completed Non oxidizers Review Dosing Schedule and Amount Used vs. Contact Time (Feed/Bleed Issues) Oxidizer – Semi-Continuous; Frequency and Duration for 1 to 2 ppm FAC Applied. Minimum 0.5 – 1.0 ppm 4hours/24hours Oxidizer – Continuous; 0.2 to 0.5 ppm FAC go to 0.5 – 1.0 ppm FAC Retest within 3-5 Days

24 Implications of the Need for Biocide Improvements
Action Level Days After Action Level 3 Completed Non oxidizer Program May Require Oxidant Use At 1/Week in Summer and ½ Weeks Winter at 1-2 ppm FAC for 1 Hour CT (i.e. 2 Hour Run Time) Semi-Continuous Oxidizer may require either / or both non oxidizer or Biodispersant Once per Week Continuous Oxidizer at 1-2 ppm FAC may require either / or both Non-Oxidizer or Biodispersant once per Week Non Oxidizer or Biodispersant Addition Maybe Required Every System Retention Time (Vol/BD Loss) May Require Online Clean Within 30 Days Retest Within 3-5 Days

25 Implications of the Need for Biocide Improvement
Action Level 5 – 14 Days After Action Level 4 Completed On-line Clean within 7 Days of This State Biodispersant Plus ≥ 5 ppm FAC for OR Biodispersant Plus ≥ 25 ppm FAC for 2 Hours Biosdispersant Plus ≥ 50 ppm for 1 Hour Test 3-7 Days Latter – Poor Results Repeat or Go to Off-line Approach

26 Implications of the Need for Biocide Improvement
Special Notes Action Levels Are a Forward Progression Upon Attaining Steady State Correction Move Backwards on the Action Levels Assuring No Return to Control State Loss It is not Unusual to have to Repeat Online or Offline Cleans as Previous Suppressed Biofilms, Sludge and Muds have now been Conditioned/ Loosened for Release to the Bulk Water

27 OSHA/Wisconsin Protocol
Confirmed Cooling Tower Source of Outbreak Turn off tower fans Shock dose chlorine donor to 50 ppm FAC Add Biodispersant Hold 10 ppm FAC for 24 hours Drain cooling system and repeat steps 2 - 4 Inspect for biofilms. If present, drain and mechanically clean.

28 Frequency of Cleaning/Disinfection

29 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

30 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

31 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.

32 Implications of the Need for Biocide Improvement
Off-line Cleaning Pre Conditioning with Blowdown to ½ COC Biodispersant and Non Oxidizer for 24 Hours Hyper Chlorination pH 7.5 – 8.0 Biodispersant ≥ 10 ppm FAC for 24 hours Drain and Flush Post Conditioning of ≥ 10 ppm FAC for 1 Hour Test 3-7 Days Latter – Poor Results Repeat or Go to Wisconsin Protocol

33 Planning and Record Keeping

34 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.

35  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.)

36 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.

37 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

38 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.

39 “Ideal System” Water flow is continuous
No dead legs or stagnant conditions Basin and deck protected from sun No evidence of sludge, debris, algae Drift eliminators installed, functioning No evidence of aerosols, drift System not near health care, aged, residential facility Low number of people potentially exposed Halogen used Biodispersant/bio-dispersing biocide used Comprehensive water treatment program Automated biocide and chemical dosing Continuous automated monitoring, control This slide summarizes ideal situations yielding the lowest potential for growth and exposure.

40 High Risk Facilities Hospitals Retirement Homes
Long-term and chronic care facilities Public facilities Offices Malls Hotels Process cooling systems that have the potential for: Aerosol spray cooling – automotive Process contamination CPI/HPI Food/Beverages

41 Cooling System Susceptibility
High airborne dirt load potential (utilization of side-stream filtration) Nearby construction Lack of ground coverings with aggregate materials or vegetation High nutrient load potential Process side inleakage Tower near chemical, food or vehicle exhaust

42 Cooling System Susceptibility
Cooling tower air discharge near proximity to fresh air intakes or open windows of building, and/or outdoor population (i.e. ground level).

43 Cooling System Susceptibility
No operation or intermittent operation of equipment while wet: Drain if stagnant > 1 month Idle - rotate weekly or install 5 – 10% slip stream flow Dead legs or seasonal cross-over lines Remove them or Loop them with 5 – 10% slip stream flow Close shut-off valves at flowing supply and drain the remainder of the branch system and equipment

44 Influence Risk Associated With Legionella

45 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

46 Factors Contributing to Legionella Health Risks in Cooling Systems
Biofilm Temperature and pH Organic Contamination Aerosols Algae and Protozoa Scale and Corrosion Stagnant Water Condition of Drift Eliminators High Levels Of Heterotrophs (i.e. CFU/ml) Exposure to Sunlight Intermittent Operation Tower Repair Presence of Legionella Quality Bio-Control Program Proximity To Populations

47 TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS
ISSUE CONDITION CORRECTIVE MEASURE COOLING TOWER (C.T.) LOCATION GROUND LEVEL AND/OR DIRECT EXPOSURE TO POPULATION C.T. AIR DISCHARGE NEAR BUILDING FRESH AIR INTAKE C.T. AIR DISCHARGE NEAR WINDOWS IN BUILDINGTHAT OPEN NONE A DESIGN CONSTRAINS NONE, A DESIGN CONSTRAINT, USE THERMOGRAPHY TO DETECT DISTANCE OF AIR TRAVEL WRT INTAKE LOCATION NONE, A DESIGN CONSTRAINT, OR FIX WINDOWS CLOSED, USE THERMOGRAPHY TO DETECT DISTANCE OF AIR TRAVEL WRT WINDOW LOCATION. MAKE-UP UNCLARIFIED, UNFILTERED, NO DISINFECTION PRETREATMENT EFFECTIVELY OR GO TO POTABLE WATER SOURCE HIGH AIRBORNE DIRT LOAD NEAR BY CONSTRUCTION AND OR EXCAVATION LACK OF GROUND COVER TEMPORARY, STEP-UP BIO TREATMENT APPLICATIONS, USE SIDE STREAM FILTRATION COVER EXPOSED EARTH WITH AGGREGATE MATERIALS OR VEGETATION, USE SIDE STREAM FILTRATION (SEE ATTACHMENT I) WATER FLOW INTERMITTENT LEADING TO STAGNATION, BIOFILMS, BIO-SEDIMENTS, ANAEROBIC CONDITIONS DRAIN IF STAGNATION > 1 MONTH ROTATE EQUIPMENT WEEKLY WITH MILD STERILIZATION (5 PPM FAH, 6 HOURS) UPON RESTARTS INSTALL 5-10% SLIP STREAM FLOW PROVIDED COOLING WATER IS LOW IN SUSPENDED SOLIDS (I.E., ≤ 5NTU) OR SIDE STREAM FILTERING IS PRESENT (I.E. ≤ 25 NTU THEORETICAL).

48 TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS
ISSUE CONDITION CORRECTIVE MEASURE DEAD LEGS, SUPPLY/RETURN HEADER DEAD HEADS, SEASONAL CROSSOVER LINES BIOFILMS, BIO-SEDIMENTS, ANAEROBIC CONDITIONS REMOVE DEAD LEGS OR BLOWDOWN (HIGH VELOCITY FLUSH) EVERY 5 TO 7 DAYS LOOP SUPPLY/RETURN HEADERS WITH 5-10% SLIP STREAM FLOW PROVIDED COOLING WATER LOW IN SUSPENDED SOLIDS OR BLOWDOWN EVERY 5 -7 DAYS. SEASONAL CROSSOVER LINES AND EQUIPMENT. PROVIDE 5-10% SLIP STREAM FLOW PROVIDED COOLING WATER IS LOW IN SUSPENDED SOLIDS OR INSTALL ISOLATION VALVE AT THE FLOWING LINE TAKE OFF WITH A BLOCK AND BLEED VALUE ARRANGEMENT AND DRAIN THE SEASONAL LINE AND EQUIPMENT HIGH NUTRIENT LOAD POTENTIAL PROCESS INLEAKAGE EXHAUSTING AIR/GASES FROM CHEMICAL OR FOOD PROCESSING (VOC’S) AND VEHICLES NEAR COOLING TOWER INTAKES EMPLOY DETECTION AND CONTINGENCY MITIGATION METHODS AS DONE FOR TRADITIONAL CHEMICAL TREATMENT PROGRAMS REDIRECT EXHAUSTING AIR/GASES DIRECT SUNLIGHT ABSORPTION BY COOLING TOWER BASIN UPPER DISTRIBUTION DECK NONE, A DESIGN CONSTRAINT ENCLOSE WETTED EXPOSED AREAS WITH HINGED COVERS THAT ALLOW FOR ACCESS AND INSPECTION

49 TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS
ISSUE CONDITION CORRECTIVE MEASURE HIGH DRIFT AND AEROSOLS IN COOLING TOWER AIR EXHAUST DRIFT ELIMINATORS MISSING OR IMPROPERLY INSTALLED OLD, LOW EFFICIENCY DRIFT ELIMINATORS PRESENT CHECK DRIFT ELIMINATORS FOR PRESENCE AND CORRECT INSTALLATION. REFIT REPLACE BROKEN ELIMINATORS UPGRADE TO HIGHER EFFICIENCY DRIFT ELIMINATORS COOLING TOWER INSPECTION OF FILL, ELIMINATORS, BASIN, DISTRIBUTION DECK VISIBLE BIOFILMS, ALGAE, SLUDGE, DEBRIS ANAEROBIC/SEPTIC SMELLING MUDS, H2S RELEASE UPON HC ADDITION APPLY AGGRESSIVE CLEAN STERILIZATION PRECONDITIONING/FLUSH OF RECIRCULATION SYSTEM PAST/PRESENT BIOLOGICAL CONTROL BIOFILMS PRESENT ON DRYING COUPONS (I.E. SHEEN TO TANNISH/BROWN COLOR DEVELOPMENT) >105 CFU/ML H.B.C. > 106 CFU/CM2 H.B.C. APPLY ONLINE MODERATE PRECONDITIONING STERILIZATION HALOGEN IN USE WITHOUT BIODISPERSANT NOT EFFECTIVE IN MINIMIZING BIOFILMS SEE TABLE 4 FOUR OXIDANT LEVEL CONTROL AND TABLE 5 FOR ACCEPTABLE BIODISPERSANT DOSAGES NON-OXIDIZERS IN USE NOT BASED ON GLUTARALDEHYDE, ISOTHIAZOLINE, BROMONITROPROPANEDIOL, OR DIBROMONITRILOPROPIONAMIDE CHEMISTRY LITTLE TO NO EFFICACY TOWARD LEGIONELLA CONTROL SEE TABLE 6 FOR CORRECT NON-OXIDIZER, DOSAGE AND CONTACT TIME REQUIRED FOR LEGIONELLA CONTROL

50 Site Survey Pretreatment/Precleaning Need Assessment

51 Precleaning Determination
DEPOSIT ANALYSIS <10% LOI <40% MOISTURE <104 CFU/CM2 <105 CFU/GM NO SRB’S, IRB’S, MOLD COUPONS TUBERCLATED WITH HARD SINTERED CORROSION PRODUCT AND SHINY SILVER TUBERCLE BASE HIGH % IRON >10% LOI >40% MOISTURE >105 CFU/CM2 >106 CFU/GM POSITIVE SRB’S, IRB’S MOLD COUPONS AND SURFACES NOT SEVERELY TUBERCULATED, BASE NOT SHINY SILVER >10% LOI >40% MOISTURE >105 CFU/CM2 >106 CFU/GM POSITIVE SRB’S, IRB’S, MOLD COUPONS/SURFACES HIGHLY TUBERCULATED AND SHINY SILVER BASE LOW % IRON OFF LINE CLEANING OF AFFECTED EXCHANGERS FOR TUBERCLE REMOVAL AND REPASSIVATION, IMPROVEMENT IN CORROSION CONTROL PROGRAM REQUIRED. ON LINE BIOFILM CLEAN-UP AND STIFLING OF TUBERCLES – PLUG APPARENT POROSITY, MIXED BIO/CORROSION FOULING ON LINE BIOFILM CLEAN-UP, BIOFOULING ONLY

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

53 Monitoring and Inspection
Testing Bulk water dip slides Prior to non-oxidizing biocide addition Minimum once per week Target ≤ 104 CFU/ml Coupon surfaces - if available Prior to non-oxidizer and/or biodispersant addition Every 30 to 60 days, but be consistent Target ≤105 CFU/cm2

54 Preventive Actions Inspect and Test Domestic Waters Fountains Spas
Air Handling Units Humidifying/Dehumidifying Equipment/Coils Cooling Towers

55 Other Water Systems Treat and Maintain Similar to Cooling Tower Protocols Fountains and Waterfalls Filtration Drain Regularly Misters/Atomizers, Humidifiers, Air Washers Coils, Spray Bars, Sumps, Mist Eliminators Pre/Post Air Filtration Bleed/Drain Clean/Disinfect Sludge Removal UV – Air Space

56 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

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


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