Cooling Tower Maintenance Legionella Awareness 3rd Installment ® CTM/Ashland Presentations Legionella Awareness – 2003 Filtration of Cooling Waters – 2005 Legionella Risk Management – 2006 Legionella Proactive Protocol – 2008 Literature References ® Legionella Proactive Protocol Introduction/Refresher ASHRAE - Systems that may Harbour 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 ® Legionella Proactive Protocol Implement Risk Management Criteria Maintenance and Record Keeping – Begin now as Legislation will be forth coming – Allows for a Basis of Estimation - Man - Methods - Materials – Estimates can be Reported to Management. While Focus has been Reduction of Costs they will need Estimates as the Cost of Ownership is Going Up. ® Refresher Information ® Legionella Bacteria Source of Legionella – Pervasive organism Conditions for growth – 68 - 122 F (20 - 50 C) – pH 6-8 – Stagnant waters – A nutrient source ® Biofilms, organics Sediments, deposits Factors Determining the Risk of Contracting the Disease A source of Legionella Favorable growth conditions Aqueous aerosol Sufficient organisms to cause infection Susceptible individual ® Total System Approach: Five Areas of Activity and Performance Comprehensive system assessment Intensive microbiological treatment program Sterilization and cleaning Monitoring and control Documentation ® Preventive Actions Inspect and Test – – – – – – ® Domestic Waters Fountains Spas Air Handling Units Humidifying/Dehumidifying Equipment/Coils Cooling Towers 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 ® 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) Flowing Bulk Water Basin Chip Scale Basin Sludge Dead Head (off) Plate/Frame XER Slip Stream By-pass (10%) Plate/Frame ® Aerobic Bacteria Fungi Anaerobic Bacteria Higher Life Forms <10 1600 <10 10 <10 1,000,000 No Yes 3,500,000 20 1,000,000 Yes 400 <10 10,000 Yes <10 <10 <10 No 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 ® Oxidant Feedrate Oxidant Feedrate 5 4.5 4 3.5 3 2.5 2 1.5 Ff 1 0.5 0 Fi system biofilm demand 0.5 ppm oxidant residual raw water demand 1 2 3 4 5 6 7 8 9 Time Time to satisfy System Demand ® 10 11 12 13 14 15 tBreakthrough Monitoring and Inspection Inspection for visible slime or sludge's – Decks – Mist eliminators – Fill – Sumps – Corrosion or biofilm coupons ® 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 ® Systems That May Harbour Legionella ® 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 ® Potable Water Supply (AWWA) New Piping and Additions High Velocity Flush (HVF) initially at 8-15 ft./sec. if possible Continuous Flush at 2.5 ft/sec. – ≥ 10 ppm FAC for 24 Hours – ≥ 50 ppm FAC for 3 Hours Slug and Hold at ≥ 100 ppm FAC for 3 Hours is an alternative ® Potable Water Systems Emergency Water Systems – Stagnant/Idle – Ideal Temperatures – Reach Room Temp Eye Wash/Showers (Low to no Atomization) Fire Systems Periodically Flush ® Potable Water Systems Cold Water – Store at ≤ 20ºC (68ºF) Hot Water - Store at 50 - 60ºC (124-148ºF) - Operate Return Water ≥ 50ºC (124ºF) Eradication - Thermal - 66ºC to 70ºC (150ºF) for 8 hours and Flush outlets for 30 minutes - Chemical - ≥ 2 ppm (10 ppm) FAC for 2-24 hours at pH 7-8; Flush for 5 minutes - Copper/Silver Ionization, - 0.2 – 0.8 ppm Copper - 0.02 – 0.08 ppm Silver ® Legionnella and Water Temperature ® SPAS Hydrotherapy Pools, Whirl Pools, Hot Tubs pH 7.2 - 7.8; 7.4 - 7.6 Ideal FAC 3 - 10 ppm; 4 - 5 ppm Ideal FABr 4 - 10 ppm; 4 - 6 ppm Ideal Ultra Violet Plus Peroxide Ozone Maintenance Once per day for 1 to 4 hours at 10 ppm FAC or 10X FAC in use ® 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 RISK CATEGORY ® Influence Risk Associated With Legionella ® Dutch Frequency of Legionella Testing Minimum Risk Category Highest 1. Frequency Monthly 2. Quarterly 3. Quarterly to Yearly 4. Lowest Yearly Tests to be performed when seasonal/environmental amplification is highest, equipment change over or start ups Dutch Risk Category 1. Highest Risk – Cooling Towers < 200 meters from Hospital, Nursing Home or Health Care Facility where Occupants maybe immunologically compromised 2. Cooling Tower < 200 meters of Retirement Home, Hotel or Building Accommodating a Large Number of People 3. Cooling Tower in Residential and Industrial Neighbourhoods 4. Lowest Risk – Cooling Tower in Industrial Area > 600 metres Away from a Residential Area. ® Survey of Process Risk HIGH Humidifier/Fogger Aerosol Producing Process Misters, Atomizers Air Washers Decorative Fountains and Waterfalls Whirl Pools Hot Tubs Shower Heads Sludge/Settled Solids >⅛″ - ¼″ LOW Potable Water Hot/cold Shower Heads Cooling Towers/ Evaporative Condensers Risking increases with Location (i.e. Grounds Levels, Near Air Intakes/Windows), Local Ground Cover, Air Contamination/Approximately to Exhaust See C.T.I. Design and Maintenance Consideration Non-Visible Temperature 35ºC (95ºF) To 46ºC (115ºF) <20ºC (68ºF) >50ºC (124ºF) Biological Activity >104 CFU/ml >105 CFU/cm2 Presence of Higher Forms (OMEBA, PROTOZOA, ALGAE, MOLD, FUNGUS). ≤103 CFU/ml ≤104 CFU/cm2 No Higher Life Forms Factors Contributing to Legionella Health Risks in Cooling Systems Biofilm Algae and Protozoa High Levels Of Heterotrophy (i.e. CFU/ml) Presence of Legionella ® Organic Temperature and pH Contamination Aerosols Scale and Corrosion Stagnant Water Condition of Drift Eliminators Exposure to Sunlight Intermittent Operation Tower Repair Water Quality Bio-Control Program Proximity To Populations TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS ISSUE COOLING TOWER (C.T.) LOCATION CONDITION GROUND CORRECTIVE MEASURE 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 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, WATER FLOW INTERMITTENT LEADING TO STAGNATION, BIOFILMS, BIOSEDIMENTS, ANAEROBIC CONDITIONS DRAIN NONE, STEP-UP BIO TREATMENT APPLICATIONS, USE SIDE STREAM FILTRATION COVER EXPOSED EARTH WITH AGGREGATE MATERIALS OR VEGETATION, USE SIDE STREAM FILTRATION (SEE ATTACHMENT I) 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). TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS ISSUE DEAD LEGS, SUPPLY/RETURN HEADER DEAD HEADS, SEASONAL CROSSOVER LINES CONDITION BIOFILMS, BIO-SEDIMENTS, ANAEROBIC CONDITIONS REMOVE PROCESS INLEAKAGE AIR/GASES FROM CHEMICAL OR FOOD PROCESSING (VOC’S) AND VEHICLES NEAR COOLING TOWER INTAKES EMPLOY BASIN NONE, EXHAUSTING HIGH NUTRIENT LOAD POTENTIAL DIRECT SUNLIGHT ABSORPTION BY COOLING TOWER ® CORRECTIVE MEASURE UPPER DISTRIBUTION DECK DEAD LEGS OR BLOWDOWN (HIGH VELOCITY FLUSH) EVERY 5 TO 7 DAYS LOOP SUPPLY/RETURN HEADERS WITH 510% 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 DETECTION AND CONTINGENCY MITIGATION METHODS AS DONE FOR TRADITIONAL CHEMICAL TREATMENT PROGRAMS REDIRECT EXHAUSTING AIR/GASES A DESIGN CONSTRAINT ENCLOSE WETTED EXPOSED AREAS WITH HINGED COVERS THAT ALLOW FOR ACCESS AND INSPECTION TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS ISSUE HIGH DRIFT AND AEROSOLS IN COOLING TOWER AIR EXHAUST CONDITION DRIFT ELIMINATORS MISSING OR IMPROPERLY INSTALLED OLD, LOW EFFICIENCY DRIFT ELIMINATORS PRESENT VISIBLE COOLING TOWER INSPECTION OF FILL, ELIMINATORS, BASIN, DISTRIBUTION DECK BIOFILMS, ALGAE, SLUDGE, DEBRIS ANAEROBIC/SEPTIC SMELLING MUDS, H2S RELEASE UPON HC ADDITION CORRECTIVE MEASURE CHECK DRIFT ELIMINATORS FOR PRESENCE AND CORRECT INSTALLATION. REFIT REPLACE BROKEN ELIMINATORS UPGRADE TO HIGHER EFFICIENCY DRIFT ELIMINATORS 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 HALOGEN IN USE WITHOUT BIODISPERSANT NOT EFFECTIVE IN MINIMIZING BIOFILMS SEE NON-OXIDIZERS IN USE NOT BASED ON GLUTARALDEHYDE, ISOTHIAZOLINE, BROMONITROPROPANEDIOL, OR DIBROMONITRILOPROPIONAMIDE CHEMISTRY LITTLE SEE ® TO NO EFFICACY TOWARD LEGIONELLA CONTROL ONLINE MODERATE PRECONDITIONING STERILIZATION TABLE 4 FOUR OXIDANT LEVEL CONTROL AND TABLE 5 FOR ACCEPTABLE BIODISPERSANT DOSAGES TABLE 6 FOR CORRECT NONOXIDIZER, DOSAGE AND CONTACT TIME REQUIRED FOR LEGIONELLA CONTROL Site Survey Pretreatment/Precleaning Need Assessment Question/Observations/Analytical Results CFU/ml > 105 - 106, SRB’s, IRB’s, Mold Fungi: Present > 1 inch of sludge in Cooling Tower Distribution Decks, spray nozzle header dead ends blow off points and/or basin. Visible biofilms in Cooling Tower, fill, basins, coupons, heat exchangers (tubing, head box) Deposits Greater than 10% LOI, 40% Moisture, 10 6 CFU/gm aerobic, 104 anaerobic, or SRB’s, IRB’s, mold/fungi present Surface films contain tanish brown coloration upon drying or begin to curl up, like potatoe chips upon dehydration, > 10 6 CFU/cm2aerobic, > 102 CFU/cm2 anaerobic, or SRB’s, IRB’s, Mold/Fungi present CFU/ml, SRB’s, IRB’s or Mold, /fungi increase 4-6 hours after biodispersant added. Periodic spike increase in CFU/ml when no biocide is added. System has experienced process inleakage presently or in the past. Addition of HCI to deposits release H2S Addition of HCI to surfaces release fluffy coagulated cellulytic materials Legionella control has been poor or sporadic Yes No 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 OFF LINE CLEANING OF AFFECTED EXCHANGERS FOR TUBERCLE REMOVAL AND REPASSIVATION, IMPROVEMENT IN CORROSION CONTROL PROGRAM REQUIRED. >10% LOI >40% MOISTURE >105 CFU/CM2 >106 CFU/GM POSITIVE SRB’S, IRB’S, MOLD COUPONS/SURFACES HIGHLY TUBERCULATED AND SHINY SILVER BASE >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 ON LINE BIOFILM CLEAN-UP AND STIFLING OF TUBERCLES – PLUG APPARENT POROSITY, MIXED BIO/CORROSION FOULING LOW % IRON ON LINE BIOFILM CLEANUP, BIOFOULING ONLY Breakdown of Bacteria Often Found in Cooling Water Organism Action Total Aerobic Bacteria Multiple Actions Clostridium Slime Formers, Gas Producers, Corrosion Pseudomonas Slime Formers, Denitrifying, Deposits Achromobacter Deposits, Denitrifying Iron Related Bacteria Deposits, Corrosion Sulfate Reducing Bacteria (Anaerobic) H2S Producers, Deposits Corrosion Acid Producers (Aerobic. Faculative) Corrosion, Deposits Algae Slime, Corrosion, Fouling, Odour, Deposits Mold/Fungi Slime, Fouling, Soft/Brown/White – Rot, Corrosion, Deposits Protozoa Fouling, Slime Legionella Testing Requirements ® Survey Summary Requirements For Legionella Testing Country Testing Required Frequency Offline Cleaning And Disinfection Aust./NZ Yes Monthly 2 Consecutive ≥ 1000 CFU/ml EU Yes Quarterly ≥ 100,000 CFU/L France Yes Monthly ≥ 100,000 CFU/L Spain Yes Monthly ≥ 100,000 CFU/L Italy Yes Not Specified ≥ 10,000 CFU/L Netherlands Yes Quarterly (Monthly to Yearly Risk Based) ≥ 100,000 CFU/L Switzerland No Quarterly ≥ 10,000,000 CFU/ml HPC Singapore Yes Quarterly ≥ 1,000,000 CFU/L Japan Yes Not Specified ≥ 1,000,000 CFU/L UK Yes Quarterly > 1,000 CFU/ml USA No Not Specified Not Specified Canada No Not Specified Not Specified 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 ® Frequency of Cleaning/Disinfection ® 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 any doubt If microbiological monitoring indicates there is a problem At least twice a year ® Frequency of Cleaning/Disinfection Preconditioning/Disinfection – End of Operating Season – 2 per Year Minimum for 24/7 Systems 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 ® 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. ® Actions Levels/Associated Cleaning Disinfection ® OSHA Technical Manual (Section III: Chapter 7) Legionella Counts Action Level Cooling Tower CFU/ml Domestic Water CFU/ml Humidifier CFU/ml 1 100 10 1 2 1000 100 10 Where - AL1 – Online Cleaning and/or Biocide Treatment Improvement Required - AL2 – Immediate Online Cleaning and/or Biocide Improvement (Note: If Online Approach Does not Eradicate, then Off Line is Required) Suggested Legionella Remedial Action Criteria Legionalla (CFU/ml) Cooling/Tower Evaporative Condenser Potable Water Humidifier/Fogger Detectable;<1 1 2 3 1-9 2 3 4 10-99 3 4 5 100-999 4 5 5 >1000 5 5 5 Actions – 1. Review Maintenance 2. Follow-up Analysis and Implement Action 1 3. Implement Action 2, Conduct review of Direct and Indirect Bioaerosol Contact of Occupants and Health Risk Status of Occupants May Lead to Increased Biocide Applications or One Clean 4. Implement Action 3, Cleaning/Biocide Improvement is Indicated 5. Immediate Biocide Improvement and Cleaning is Indicated Levels have a Potential for Outbreak © 1998, Pantheon Laboratories, Pathogen Control Associates Inc. Implications of the Need for Biocide Improvements Action 3 - 14 Days After Action 2 Completed – Nonoxidizers 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 Implications of the Need for Biocide Improvements Action Level 4 - 14 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 nonoxidizer 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 On-line Clean Within 30 Days – Retest Within 3-5 Days ® 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 OR ® - Biosdispersant Plus ≥ 50 ppm for 1 Hour - Test 3-7 Days Latter – Poor Results Repeat or Go to Offline Approach Implications of the Need for Biocide Improvement Off-line Cleaning – - Pre Conditioning with 1. Blowdown to ½ COC 2. Biodispersant and Non Oxidizer for 24 Hours Hyper Chlorination 1. pH 7.5 – 8.0 2. Biodispersant 3. ≥ 10 ppm FAC for 24 hours 4. 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 ® Implications of the Need for Biocide Improvement Special Notes 1. Action Levels Are a Forward Progression 2. Upon Attaining Steady State Correction Move Backwards on the Action Levels Assuring No Return to Control State Loss 3. It is not Unusual to have to Repeat Online or Off-line Cleans as Previous Suppressed Bioflims, Sludge and Muds have now been Conditioned/ Loosened for Release to the Bulk Water ® OSHA/Wisconsin Protocol Confirmed Cooling Tower Source of Outbreak 1. 2. 3. 4. 5. 6. ® 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. OSHA/Wisconsin Protocol Refill system and operate for 1 hour at 10 ppm FAC Flush system Recharge system with water treatment additives for deposit, corrosion and biological control and return to service 7. 8. 9. Note test monthly: ® Legionella ≤10 CFU/ml HPC ≤105 CFU/ml Action Levels of One JCAHO Facility Cooling Tower Upwind from Building Air Intakes Legionella (CFU/ml) Action Level < 10 1 10 - 30 2 >30 - 100 3 >100 - 200 4 >200 5 Cooling Tower Design Best Practices ® C.T.I. Cooling Tower Design Best Practices Use High Efficiency Drift Eliminators and Operate within Design Air Velocities Plenums to be Sealed to Avoid Local Elevated Velocities within the Drift Eliminators Water Distribution Design to Minimize the Creation of Very Fine Droplets at the Louver or Eliminator Locations to Avoid Air Seal By-Pass Air Inlet and Rain Zone Design to Minimize Splash out and Aerosol Creation ® C.T.I. Cooling Tower Design Best Practice Fill Selection to Minimize – Drift and Splash Out – Poor Water Distribution – Fouling Fan Cylinder Seal to Avoid Extraneous Water Intake to the Fan Cooling Tower Not to Located Near Building Air Intakes No Dead Flow Locations in Tower Basin Ensure Equalization Piping are Not Stagnant Side Stream Filtration ® Sand Filtration 5 Micron Media Particle Size Microns Percent Of Total Before Filtration After Filtration Percent Reduction 1–5 86.3 44,879,400 346,760 99.2 5 – 10 10.7 5,588,600 36,920 99.3 10 – 25 2.7 1,410,600 24,060 98.3 25+ 0.3 126,800 8,760 93.1 Totals 99.0 52,005,400 416,500 99.2 •Finer the Size, more Surface Area and Nutrient Value •Typical Size of Bacteria – 0.2 – 0.45 Micron Spores – 0.1 Micron Protozoa - >50 Micron Diatoms - >20 Micron Algae - >100 Micron •1 Micron = 0.00004 (4 x 10) Inches Considerations for Filtration Total Suspended Solids Leading to – UDC – Loss of Biofilm Control or High Biocide Demands for Bulk Water Biocontrol – Mass Balance Verification of Scale and/or Corrosion Inhibitor Adsorption Losses – Settled Solids Harboring Bioactivity, Higher Life Forms – Periodic Biocount Spikes for No Apparent Reason – Presence of Visual Biofilms and Agglomerates ® Suspended Solids Control Target (First Case Approximation) As per Tower Fill Manufacturers Recommendations Tower Sump Sludge < 1" Tower Distribution Deck/Lateral Sludge <⅛" - ¼" Tower Fill Deposit Loadings ≤ 0.00187 lbs./ft3/day Filtration or Chemical Dispersants for TSS Values Greater than 10 ppm in the Cooling Tower Water Ensure Cost Effective Biocontrol is Practiced – Planktonic - ≤ 103 CFU/ml – Sessile - ≤ 105 CFU/cm2 ® How to Size and Apply Filtration Side Stream with Distribution and Collection Laterals Laterals Operated at 10 – 15 ft./sec. Jet Nozzle Enhancements Increasing the Area of Influence Worked Example Given for Application Design ® ® ® ® Maintenance Considerations ® C.T.I. Maintenance Considerations Louvers – All in Place, Correctly positioned, Free of Biomass and Deposits Piping Dead Legs – Remove or Loop Recirculate, or Bleed/Flush Frequently (Also Applies to Equalization Lines) Cold Water Basin – Any Significant Accumulation of Organic Matter, Dirt and Debris to Be Removed. If Cleaning Requirements are Frequent Consider Filtration ® C.T.I. Maintenance Considerations Cross Flow - Hot Water Basin – Leakage Corrected to Avoid Entrained Water into Air Stream – Missing/Broken Nozzles to be Replaced – Overflowing Water to be Corrected – Cover Against Sunlight and Wind blow Debris Instruction Counter Flow - Spray System – Free of Fouling and Properly Positioned – Avoidance of Water Passage into Eliminators ® - Misaligned Spray Nozzles Corrected - Leakage of Pipe Joints or Corrected Nozzle C.T.I. Maintenance Considerations Eliminators – Free of Organic/Inorganic Debris – Replace Damaged or Missing Eliminators – Correct Gaps Between Eliminators, Casing, Structural Elements, Air Seals, and Plenum Framework Fill – Replace Damaged or Deteriorated – Presence of Fouling, then Review/Inspect: ® - Water Distribution/Spray Nozzles - Louvers - Air Seals - Water Treatment Program and Control C.T.I. Maintenance Considerations Leakage Corrected to Avoid Entrained Water into Air Stream Missing/Broken Nozzles to be Replaced Overflowing Water to be Corrected Cover Against Sunlight and Windblown Debris Intrusion. Counter Flow Spray System – Free of Fouling and Properly positioned – Avoidance of Water Passage into Eliminators - Misaligned Spray Nozzles Corrected - Leakage of Pipe Joints or Corrected Nozzles ® C.T.I. Maintenance Considerations Filtration Equipment – Periodic Media Cleaning and Disinfection - Once per Year - CFU/ml Counts Outlet > Inlet After Backwash - Alkaline Detergent Air Lance/Bubble Mixing for 2 to 4 Hours – Backwash - Chlorination at 100 ppm FAC Air Lance/Bubble Mixing for 2 to 3 Hours - Backwash ®