Most people are not aware of the long history of UV in water disinfection and that UV is rapidly gaining popularity as an effective alternative non-chemical water disinfection.
Ultraviolet disinfection of water has a long and well-proven history. UV light has long been accepted as an effective germicidal treatment, and has been installed in many major public drinking water and wastewater treatment plants worldwide.
Although it’s taken a long time for the technology to become widely adopted, UV has been around for a long time. In 1877, the germicidal properties of sunlight were discovered and it was only a matter of time before people tried to apply this knowledge for practical use. In 1903, Niels Fensen received a Nobel Prize for his use of ultraviolet light to combat tuberculosis (although not in water), and in 1910, the first drinking water disinfection system opened in Marseilles, France.
From that time on, the technology changed very little until the 1930s, when the first tubular lamps were developed, allowing for easier applications and different configurations for use. In the 1950s, the first truly significant research of UV disinfection began. By the 1960s, UV disinfection was becoming more widely used in commercial applications and was creeping into the residential market.
Today, ultraviolet disinfection is widely accepted as an effective treatment for the removal of microbiological contaminants from water.
Even highly chlorine-resistant microbes such as Giardia and Cryptosporidium can be effectively disinfected from water with UV. NSF-certified UV systems are becoming an increasingly popular alternative to chemical treatment for many applications.
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Ultraviolet (UV) Radiation
What is UV radiation?
Ultraviolet (UV) radiation is a form of electromagnetic radiation that comes from the sun and man-made sources like tanning beds and welding torches.
Radiation is the emission (sending out) of energy from any source. There are many types of radiation, ranging from very high-energy (high-frequency) radiation – like x-rays and gamma rays – to very low-energy (low-frequency) radiation – like radio waves. UV rays are in the middle of this spectrum. They have more energy than visible light, but not as much as x-rays.
There are also different types of UV rays, based on how much energy they have. Higher-energy UV rays are a form of ionizing radiation. This means they have enough energy to remove an electron from (ionize) an atom or molecule. Ionizing radiation can damage the DNA (genes) in cells, which in turn may lead to cancer. But even the highest-energy UV rays don’t have enough energy to penetrate deeply into the body, so their main effect is on the skin.
UV radiation is divided into 3 main groups:
1. UVA rays have the least energy among UV rays. These rays can cause skin cells to age and can cause some indirect damage to cells’ DNA. UVA rays are mainly linked to long-term skin damage such as wrinkles, but they are also thought to play a role in some skin cancers.
2. UVB rays have slightly more energy than UVA rays. They can damage the DNA in skin cells directly, and are the main rays that cause sunburns. They are also thought to cause most skin cancers.
3. UVC rays have more energy than the other types of UV rays. Fortunately, because of this, they react with ozone high in our atmosphere and don’t reach the ground, so they are not normally a risk factor for skin cancer. But UVC rays can also come from some man-made sources, such as arc welding torches, mercury lamps, and UV sanitizing bulbs used to kill bacteria and other germs (such as in water, air, food, or on surfaces).
