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Web Exclusive - April 2012

Cleaning the Water, Clearing the Air

How UV Water Treatment Improves Water and Air Quality

By Jeff Boynton


Swimming pools are one of the most popular forms of exercise in North America. Exercising while swimming has been long recognized for cardiovascular health benefits and fitness. However, water is how life started on this Earth in a microbial level, and that is still true today.

Many water-borne pathogens have been treated with various methods over the years. Today, ultraviolet water treatment is being discussed more and more as a valid alternative for water treatment in recreational water facilities. There is much discussion recently about the MAHC guidelines, which address many of these concerns for providing properly sanitized recreational water facilities.

As frequent reports about recreational water illness and bacteria outbreaks abound in the press, many commercial pool operations are choosing UV sanitation in order to comply with water quality testing parameters and state mandates. Some residential pool owners are even turning to UV water treatment for its ease of use, reduced chemical consumption, health advantages and environmentally friendly benefits.

UV treatment of water is a terrific way to sanitize swimming pool water, but it is also a great product to use in order to improve the air quality around swimming pools—especially indoor pools. This article will explain what UV is, which UV products are appropriate for particular pool types and sizes, and how UV can improve water and air quality in and around swimming pools and spas.

UV water treatment is based on using the power of germicidal light to disinfect water, thereby consuming fewer chemicals and allowing them to be more effective. UV-C eradicates microorganisms that pass through the UV light chamber, but it does not act as a residual. UV light technology only works on the water flowing through the light chamber; it does not work on the dead zones of the pool. Reducing chemicals means cleaner, less aggressive water that is easier to balance.

What Is UV?

Ultraviolet radiation is an invisible light emitted from the sun. More than 100 years ago European scientists from different countries discovered the top surface of lake water was sterile when exposed to sunlight. Investigation led to the discovery of ultraviolet light and to the invention of UV bulbs. Ultraviolet (UV) light is situated in the electromagnetic spectrum between X-rays and visible light. UV light is split into four main categories, UV-A, UV-B, UV-C and Vacuum UV. The area between 240 and 280 nanometers (nm) is UV-C, commonly known as germicidal light. This is the UV light that is used to sanitize swimming pool water.

How Does UV Sanitize Water & Improve Water Quality?

UV-C light has the ability to cause permanent damage to a wide variety of microorganisms in water. Certain species of microorganisms, such as the news-making protozoa Cryptosporidium, are not completely sanitized with traditional disinfection techniques such as chlorine. UV-C light is not a biocide but disrupts the micro-organism's DNA, ensuring that organisms present in water are unable to replicate and remain inert. The natural phenomenon of ultraviolet radiation is reproduced inside reactors via powerful lamps that emit germicidal UV-C radiation. All germs, viruses, bacteria, etc., are thus deactivated and can no longer reproduce. Unlike other sanitation treatments, UV does not affect the taste, color or pH of the water being disinfected.

In a UV sanitation system, the pool water circulates directly under the exposure of the UV lamp, allowing the radiation to eliminate protozoans, viruses and bacteria. UV has gained traction in part because of its ability to eliminate chlorine-resistant microorganisms such as Giardia and Cryptosporidium, which are common causes of recreational water illness and pool closures.

Although this technology has been known for a long time, since 2000 improvements have led to UV water treatment technology's use in Europe. UV light sanitation is more prevalent in Europe where it has been successfully installed in commercial pools. Many studies have been conducted proving how UV light not only disinfects but also removes chloramines. The European centers for water standards such as DWG and O-Norms have certified UV light reactors as effective in improving the quality of the pool's water and air, thereby saving valuable resources.

Choosing UV to Improve Water & Air Quality

We all know that pool water must be sanitized and clean. Pools must be treated with chemicals continuously in order to deactivate pathogenic microorganisms and to prevent the spread of waterborne illness. Unfortunately, chemicals such as chlorine react with organic and mineral compounds, resulting in harmful and smelly byproducts, among which is nitrogen trichloride—or what people commonly call 'chloramines.'

Ensuring good water chemistry is the key to maintaining a proper and safe swimming pool environment—not only to maintain a good level of oxidizers but also to correctly monitor pH, water hardness, alkalinity, etc. However, there are only a few options available to pool operators looking to reduce chloramines in their pool environments (which not only smell, but are harmful to swimmers' lungs). The five available techniques are: hyper-chlorinating, non-chlorine shocking, ozone, adding fresh water or installing an ultraviolet sanitizing system.

But before explaining these techniques, "prevention" and a "good filter" go a great way toward helping reduce chloramines.

Chloramines are produced in chlorinated water when bathers introduce ammonia and organic compounds into a swimming pool and these pollutants combine with chlorine gas. If bathers shower prior to swimming, removing body perspiration, body oils and other lotions, this substantially reduces chloramine creation but does not eliminate the issue. Making sure children use the bathroom frequently so they do not urinate in the pool can also drastically lower chloramine creation.

It is always possible to enhance the filter, such as by adding granulated activated carbon, will help remove chloramines and ammonia. Filtering is critical in pool sanitation and may require additional attention and manipulation.

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