Ultraviolet Disinfection BIO-SECURITY Specification, Operation and Maintenance in a New Era

Transcription

1 2010 AALSO Symposium Moody Gardens Presented By: Dan Dycha Ultraviolet Disinfection BIO-SECURITY Specification, Operation and Maintenance in a New Era

2 Agenda Why UV? UV Basics Types of Hg Lamps UV Design Parameters Installation Maintenance

3 Applications Utilizing UV Aquaculture Aquariums Fountains/Ponds Water Features Hospitality Water Parks Water Reuse Wastewater Ponds Pool and Spa Zoos Cruise Ships

4 Ultraviolet Sterilization: The Proven Form of Reliable Waterborne Pathogen Disinfection. UV Treatment is: 1. Safe to fish and humans, leaving no residual in the water or atmosphere 2. Cost-effective, from initial equipment purchase to the overall cost of ownership 3. Stable, consistent, and easily monitored 4. A proven and reliable pathogen disinfectant, when applied properly.

5 Prerequisites of Successful UV Disinfection. Step One: Identify the Targeted Microorganism and its required UV Dose for effective treatment. - Shown here: Part 1 of 3: Algae, Bacteria, and Fungi

6 Prerequisites of Successful UV Disinfection. - Shown here: Part 2 of 3: Protozoa.

7 Prerequisites of Successful UV Disinfection. - Shown here: Part 3 of 3: Viruses.

8 Prerequisites of Successful UV Disinfection (continued). The Germicidal Action Spectrum Curve is identified on the Spectrum of Light chart below; of which, UV-C s 264 nanometers is the most efficient wavelength for living microorganism disinfection.

9 Prerequisites of Successful UV Disinfection (continued). Step Two: Identify the Application s Percent UV Light Transmissibility (%UVT). %UVT is the measurement of UV-C light transmittance in water. Contaminates and other waterborne agents will absorb UV light. Knowing the actual condition of the application s water is essential for calculating an accurate UV flow rate and ultimately achieving successful UV treatment! A credible UV Manufacturer will allow you to submit an application water sample and will provide you with %UVT test results. The test sample should represent a worse case scenario. Step Three: Identify the Application s Minimum & Maximum Operating Water Flow Rate.

10 Typical Values For UV Transmittance Type of Water Typical UV Transmittance (1 254 nm Ultrapure Water (RO/DI) 98% Drinking Water 80 96% Swimming Pool Water approx. 90% Sea Water 70 90% Zoo/Aquarium 70 90% Water Reuse 70 85% Wastewater 35 60%

11 UV Transmittance is KEY! However, other factors are relevant: Particles / Suspended Solids Impact depends on size of the particles All particles absorption of UV light Particle size distribution: particles > 10 mm impact disinfection Resulting in: Slower inactivation rates (tailing of dose-response curve) Residual microbial population not able to be disinfected (plateau of dose-response curve) Removal of particles improves UV disinfection

12 UV Fluence (Dose) Rate The UV intensity calculations for the Lahonton NFH project were performed using version 2.12 of the UVCALC UV modeling program by Bolton Photosciences Inc. Applied fluence (Dose) from 85% to 95% transmissibility : 5000 GPM: Applied UV fluence 85% T = mj/cm2 Applied UV fluence 90% T = mj/cm2 Applied UV fluence 95% T = mj/cm2

13 Prerequisites of Successful UV Disinfection (continued). Step Four: Select a Reliable UV Brand/Manufacturer that provides third party validated Equipment specifications. s. This manufacturer should also have a good reputation with customer support! The UV equipment design and flow rates should be based upon Established Engineering Guidelines as found in the Bolton Photosciences, Inc. Ultraviolet Applications Handbook and UV CALC Modeling Program, both of which are recognized by the EPA, and the EPA s Guidance Manual itself.

14 Successful UV Disinfection Achieved!

15 Successful UV Disinfection Achieved!

16 UV Design Parameters UV Dose = Retention Time x Intensity [mj/cm²] = [s] x [mw/cm²] Average Retention Time Flow Rate / Reactor Volume Min. Velocity Max. Velocity Headloss Average Intensity Lamp Output Lamp Age Quartz Sleeve Transmittance Water Quality (UV Transmittance)

17 UV Sterilizer Design. The UV Lamp is the most critical operating component of any UV Sterilizer. It determines overall equipment performance, initial unit price and cost of ownership.

18 Types of Hg UV Lamps Low-Pressure Monochromatic Output Medium- Pressure Polychromatic Output Source: EPA UV Disinfection Guidance Manual, November 2006

19 Criteria For Optimized UV Lamps High output in UV-C Low power consumption Stability against temperature Low tendency against quartz fouling Simple maintenance

20 UV Sterilizer Design (continued). UV Lamp Field Array The UV Lamp s operating performance establishes the dimensions of the UV exposure chamber. Lamp length and UV-C Output are among the most critical performance factors used to design the lamp array in order to best utilize the lamps UV output. Shell & Tube Style Open Channel Style

21 UV Sterilizer Design (continued). Optimal UV Lamp Performance Ballast(s) specifically matched to the UV Lamp s operating Requirements (driving the lamp at peak output & maximizing using life). UV Lamp Array utilizing the lamp s output to its maximum potential

22 UV Housing & Power supply Mounting Prior to initial operation check all quartz sleeve retaining nuts for tightness; retighten if necessary. The UV Sterilizer should be placed after the mechanical filter; commonly, at the end of the filtration loop. Lamp Connection (lamp not in final position)

23 UV Housing Position UV Housing Position: Vertical Position Electrical end must be positioned at the top. The Inlet must be at the bottom and the Outlet at the top to ensure your safety. Horizontal Position Inlet / Outlet Ports must face directly upward. In this position the inlet and outlet are interchangeable; it is your choice. Proper positioning will eliminate the chance of air becoming trapped inside the UV body. Please follow these mounting recommendations Closely to ensure proper water flow and safe equipment operation. Failure to remove trapped air can result in the rupture of or heat damage to the UV Housing!

24 UV By-pass Loop By-Pass If you wish to use the unit in a by-pass loop, isolate the UV from the main line using 3-way valves. The unit may require an automatic air bleed system be installed.

25 Routine Maintenance & Replacement Parts 1. Replace lamps per manufacturer s recommended specifications : Low-Pressure typically 8,000 12,000 hours & Medium-Pressure typically 4,000 8,000 hours 2. Replace quartz sleeve compression gaskets each time the corresponding lamp is changed. 3. Clean and inspect quartz sleeves periodically (every 6 to 12 months.) It is recommended to replace Quartz Sleeves should they exhibit hairline cracks, gouges, pitting or permanent mineral deposits or stains. 4. Replace lamp connectors if they show signs of corrosion on the lamp power cords. 5. Replace the ballasts if they fail.

26 Quartz Sleeve Cleaning Turn off your water supply to the UV Sterilizer. With the electrical power shut off, drain the water from the UV Housing. Remove the quartz sleeves compression fittings. Gently slide the quartz sleeves out of the UV Housing and inspect for breakage, calcium or dirt. To Clean: Dirt Use a mild dish washing detergent, thoroughly rinse and dry before reusing. Calcium Use Muriatic Acid or vinegar to dissolve the calcium, thoroughly rinse with clean water and dry before reusing.

27 Quartz Sleeve Installation (continued) Tighten all retaining nuts or compression fittings for each Quartz Sleeve position. Perform a water test after to verify that each Quartz Sleeve compression fitting achieves watertight seal.

28 Clear Documentation