UV radiation has been used for disinfection in Europe for almost a century, however in North America is still considered a new technology. It presents by itself a low cost and efficient alternative to chemical disinfection. Its only disadvantage is the lack of residuals for keeping the microorganisms inactivated.
A regular UV system consists of five essential elements:
1) UV lamps
3) Reactor Design
4) Cleaning System
5) Control System
UV lamps: There are basically three different types: low-pressure, low output lamps (LP/LO); low-pressure, high-output lamps (LP/HO) and medium-pressure (MP) lamps. LP lamps emit UV light at the generally accepted germicidal wavelength of 254nm. MP lamps are polychromatic and they have an UV electromagnetic emission spectrum of 200-400nm. Input power is several times higher for MP lamps compared to LP lamps. MP lamps have a lower efficiency and a shorter lamp life, however they require a smaller footprint and have a lower head loss.
Ballasts: They can be electronic or electromagnetic. They both present their own advantages and disadvantages. Electromagnetic are large, they have low efficiency but have a long reliable life. Electronics are small, efficient but have a higher risk of damage and a short life. Unless there is a significant power-supply variability, which negatively affects electromagnetic ballasts but only has a small effect on electronic ballasts, electromagnetic ballasts are the most viable option for UV systems.
UV Reactor Design: The reactor should be able to deliver a good turbulent or transition flow in a small footprint and with a minimal head loss. The turbulent flow is required in order to uniformly expose all fluid particles to the UV radiation; nonetheless this should be properly optimized in order to reduce the head loss.
Cleaning System: It can be chemical or mechanical. Their primary function is to remove scale formed in the lamps. A mechanical system can operate without interrupting the process but it has a limited cleaning power. Chemical systems have a larger footprint and additional components (Metering pump, chemical tanks, piping, etc.) but they have a higher cleaning capacity.
Control System: UV systems can operate with a proprietary controller or with a generic PLC. A PLC system is much more compatible with other technologies such as SCADA and also has a higher flexibility for expansion.
All these variables should be carefully evaluated and analyzed in order to properly size and design an efficient and trouble-free UV System. Let Napier-Reid be your single solution for all your water treatment requirements.