Cooling Tower & Disinfection
About UV Cooling Tower and UV
Cooling towers and re-circulation loops are considered heat rejection systems. They move heat to the atmosphere through the cooling of water to a lower temperature. Some common applications for cooling towers are air-conditioning systems, water-cooling of equipment and general manufacturing needs.
The type of heat rejection in a cooling tower is defined as “evaporative” in that it allows a small portion of the water being cooled to evaporate into a moving air stream to provide significant cooling to the rest of that water stream.
As this happens, the cooling towers become efficient air cleaners (scrubbers). This process allows airborne contaminants and particles to become deposited into the cooling water. This, combined with the contaminants in the feed water, creates an environment for microorganism growth, solid deposits and scaling.
Microorganisms tend to thrive in the re-circulated water and on wet surfaces. Bacteria, slime and algae foul heat– exchanger surfaces and in some cases attack
and destroy system components.
Problems Associated With Cooling Tower Water
1. Growth of Microorganisms
2. Downtime associated for system cleaning
3. Reduces overall lifespan of equipment
4. System downtime for cleaning
Treatments Without Ultraviolet and Their Issues
In order to avoid the biological growth problems, facility operators generally use chemicals (biocides) to stop bio-growth. While the use of chemicals helps control the overall biological problems, this solution does have downsides, they are as follows:
1. Hazardous to operators
2. Some microorganisms are found to be resistant to chemicals
3. Costs associated with storage and insurance of the chemicals
4. Constant feeding of chemicals
5. Chemicals usage adds up over time turning out to be expensive
UV for Bacterial and Virus Control
Ultraviolet Light: Ultraviolet (UV) light is invisible radiation with a range of the solar spectrum. UV is similar to the wavelengths that are produced by visible light, but much shorter. UV radiation is measured in millionths of a millimeter, i.e., Angstrom units. Ultraviolet lamp radiation of 2537 Angstrom units (or 254 nano-meters) wavelength must hit the microorganism to inactivated, and each microorganism must absorb a specific amount of energy to be destroyed.
Benefits of using the alternative method with Ultraviolet (UV) light(s)
1. No chemicals – this means it is environmentally
2. Continuous operation, systems are designed to run 24-7
3. Effective on a wide range of pathogens
4. Low operating costs
5. Low maintenance
6. Lowers the need for biocides significantly
7. No operator licensing is required
8. Safe for the environment
9. EPA approved
In order to make the addition of UV a reality, the cooling tower water treatment will also need to include a filtration system. The use of basic filters (40 to 50 micron) will help remove the solids from the water. This will make the UV more effective and prevent solids from settling elsewhere in the cooling loop.
This has a two-fold impact. The first is that it will prevent the UV system from becoming fouled and the second is that it will lower the maintenance on the actual cooling equipment (condensers and exchangers).
Integration and Sizing
Depending on size and desired results of the facility, the following needs to be determined:
What is the flow rate in gpm (gallons per minute)?
How much water is contained in the entire loop?
How many times per day does the system re-circulate?
Since the water will be re-circulated, it will have multiple passes in front of the UV on a given day. The integration of the UV/filtration will significantly reduce the amount of biocides required.
Our UV/Filtration systems are designed with the following components:
1. Stainless steel UV system
2. Manual or automatic quartz cleaning system
3. UV monitoring
4. Run time meter
5. 40 to 50 micron filter (bag, cartridge or sand)
The above can be installed in the loop and results can be seen immediately.
By integrating a combination UV disinfection and mechanical filtration system, the facility can significantly reduce the amount of chemicals required (a small amount of chemicals is required to prevent growth on the sides of the piping as well as in the equipment) and the costs associated with purchasing and storing them.
In addition, this will create a safer work environment and allow the facility to operate as a “green” company.