What is UV sterilization?
1. WHAT IS UV LIGHT?
Everybody has seen a prism split light into its component colours, or seen a rainbow where moisture in the air has split light from purple/blue through to red. What is not immediately obvious however is that each of these colours has it’s own properties and energy levels.
Ultraviolet light is the invisible light beyond the purple/blue end of the light spectrum. UV is high energy, short wavelength light. The water treatment industry uses high powered UV light called UV-C or “germicidal” ultraviolet light to disinfect water.
2. WHY IS UV LIGHT USED FOR STERILIZING WATER?
i. IS YOUR WATER SAFE?
Did you know that studies have shown that 20%-40% of wells in any given area are contaminated? Bacterial contamination of your well water can result from contaminants leaching into the ground water, or from surface water entering your well. A poorly sealed well or improperly maintained well can allow bacteria from a variety of sources to enter your drinking water.
ii. WHAT DOES UV LIGHT REMOVE FROM THE WATER?
The high energy associated with today’s germicidal or UV-C light kills disease causing bacteria including E.Coli, coliform, as well as cysts such as Cryptosporidium, and Giardia.
iii. DOES UV LIGHT ADD ANYTHING TO MY WATER?
UV sterilization uses no chemicals and adds nothing to your water. There is no change to the water’s taste, odour, etc.
3. HOW EFFECTIVE IS UV LIGHT IN STERILIZING WATER?
i. HOW DOES UV WORK?
The high energy of UV light disrupts the genetic core in the nucleus of the bacteria or cyst. The bacteria’s DNA is destroyed by the UV. The bacteria cannot reproduce and die.
The water flows through the stainless chamber of the UV unit and is exposed to the UV light. The lethal does of energy kills the bacteria instantly. There is no chemicals added and no residual bactericide to contaminate your water.
ii. 99.99% EFFECTIVE!
Manufacturers have tested UV units and have proven they are 99.99% effective in destroying bacteria and other harmful microorganisms, including Cryptosporidium & Giardia.
iii. CRYPTOSPRIDIUM & GIARDIA
Some harmful bacteria can form “cysts” as part of their life cycle. A cyst is a protective shell around the bacteria that can protect it under some circumstances. Modern UV systems are designed to emit sufficient energy to kill cysts as well as other bacteria.
4. HOW DO I SELECT OR SIZE A SYSTEM FOR MY APPLICATION?
i. SIZING AND INSTALLING.
The UV unit must be sized according to the flow of your pump. While they are not difficult to install, you should consult a water treatment professional to ensure you have the correct unit for your application.
Many units have been installed without proper pre-filtration. A 5µ prefilter must be installed before the UV unit to filter out sediment or other particles that may prevent the UV light from reaching the bacteria. Particles that may not be visible to the naked eye are enough to shield bacteria from the UV light or reduce the amount of UV light the bacteria receives. This will make your UV unit ineffective.
5. WHAT MAINTENANCE COSTS ARE REQUIRED WITH UV SYSTEMS?
To ensure your UV unit is putting a sufficient dose of UV light into your water, you must change the lamp annually. Tests have shown that the intensity of UV light degrades as the lamp ages and after a year may not be emitting sufficient UV light to kill bacteria, especially cysts.
Most modern UV units now have a timer built into the power supply so the power supply will alarm after one year even if the lamp has not burned out. For your safety you should change the lamp immediately.