How Does Ultraviolet Water Treatment Work?

Ultraviolet (UV) water treatment works by exposing microorganisms (such as cryptosporidium, giardia lamblia and more) to UV radiation, via a special UV light bulb, which disrupts their DNA and disables their ability to replicate.

What is UV?

UV is Ultraviolet radiation, an energy band within the electromagnetic energy spectrum. It is a colorless, tasteless, odorless and chemical free way to ensure your water supply is safe and clear of germs and other microorganisms that can make you sick. UV does not affect sediment, particulates or other mineral contaminants which will require additional water treatment methods.

UV Water Treatment Equipment

Factors affecting Ultraviolet Water Treatment Effectiveness

The following factors are common obstacles that will reduce the effectiveness of UV disinfection:

Particulates and sediment. These suspended solids will block the UV Rays from passing through the water. They can act as a shield, "protecting" germs from UV light. Suspended solids should be physically removed from water by mechanical pre-filtration before the water goes to a UV system.
Iron/manganese will cause discoloration on the quartz sleeve that surrounds the UV lamp and reduces the transmission of UV light, they will also absorb UV energy. Iron and Magnesium should be removed from water by pre-treatment or at least reduced to no more than .3 ppm for iron and no more than .05 ppm for manganese.
When water is hard, scale will eventually build up on the quartz sleeve around the UV lamp and will stop the UV light from passing through. A water softener should be used before an UV unit if the water is hard.
Other organic and inorganic dissolved substances can also reduce the germicidal effectiveness of UV light and should be pre-treated before an UV unit.

Limitations OF UV Water Treatment

Excessive bacteria counts in water may require additional UV dosages or chemical treatment. Other factors, such as water temperature, should also be considered. UV units are normally designed to operate best between two and forty degree Celsius. Freezing will cause damage to the UV unit and water temperature higher than forty degree C will cause a reduction in UV energy and therefore, a reduced germ kill ratio.

Advantages of UV Water Treatment Systems

UV has many advantages over other disinfection processes:

UV is effective and quick. No need for holding tanks and reaction times. No need for storing chemicals.
UV does not alter the taste of water, which makes it ideal for use in bottling plants and food processing applications.
UV is safe. NO need to add or handle hazardous chemicals or risk polluting the environment.
UV is compatible with all other water treatment processes. No need for de-chlorination if using RO systems. In fact, UV enhances the use of other water treatment by keeping them free from germs.
UV is economical. Almost always, the cost of UV disinfection units is much less than the cost of chemical treatment systems. The cost of service and maintenance of UV units is very low. The electrical running cost of an UV unit in a house is about that of a regular light bulb.
UV is more effective against viruses than chlorine.
Easy installation. UV units are very easy to install and require very little space.

Ultraviolet Water Treatment Applications

The use of ultraviolet water treatment systems is common in residential, commercial and industrial applications, as well as in sewage treatment plants. UV is also an effective tool in pond algae control. UV can be used in: homes, cottages, hotels, motels, buildings, factories, rinse processes, bottling plants, food processing, cooling towers, breweries, hospitals, fisheries, farms, wineries, and the list goes on.

Installation guidelines

Ultraviolet water treatment units should be installed after any water pre-treatment process, just before the cold and hot branch lines. If in doubt about the size of an UV unit that is needed, always use a larger unit rather than a smaller unit. Normally, an 8gpm UV unit will be installed as close as possible to the dispensing point. All the pipes should be treated with chemical shock treatment and flushed thoroughly before an UV unit is commissioned and prior to its use.

UV dis-infection is very quickly gaining ground on other conventional disinfection processes because it is effective, environmentally friendly and economical. UV does not change the taste of water and does not add anything to it. For many applications, it is the ideal choice for disinfecting water.