What is Ultra Violet? What's the connection between wavelength and effectiveness in killing bacteria? What are the ways to use Ultra Violet? What are the advantages of this method and how can you combine it with other purification methods?

Ultra violet light is electromagnetic radiation.

The electromagnetic radiation map - the spectrum - is characterized by the wavelength of each wave in its group: Radio waves in Meters, Micro waves in Millimeters, Infrared in Microns, the visible light and Ultra Violet in Nanometers (One meter = 1,000,000,000 nm) and the shortest waves - X waves and Gamma radiation.

The short area between 200-300 nm is called: the "a biotic area" - deadly for live creatures. When microorganisms were radiated with lamps that produced a biotic wave length - it was found that the deadliest wavelength is 260nm.

Low pressure Mercury lamps produce 85 percent of their power in a wavelength very close to 260nm. This attribute makes them efficient in purifying water and other materials removing microorganisms.

Methods:

There is a variety of methods to use UV lamps:

• Exposing surfaces to UV light.
• Transferring solids, liquids, gas and air through the radiation area. This transfer can take place in rooms, containers, open and closed channels and transparent pipes that has either a UV lamp in the centre or several lamps externally.

Considerations:

Before operating a UV system, several factors should be considered:

1. The sensitivity of the energy that will be used for purification. This is being measured in Microwatts seconds per square centimetre. Different organisms in different development stages require different energy levels
2. Using a UV system doesn't mean that contamination in the rest of the cooler won't occur. That's why the lamp should be positioned as close as possible to the faucet
3. A temperature of 30-40 degrees, which is essential to the maximal production of the lamp can be obtained by the isolation of the lamp with a quartz sleeve
4. If the lamp is being turned on often, it will wear out quickly. (The lamp life is between 7,500-10,000 hours).

The main advantages in this method ate that there are no chemical modifications taking place in the system and there are no dangerous by-products.

Usage:
It's low cost, ease of use and no need for added chemicals make this method more common as a stand-alone method or in tandem with additional purification methods:

Drinking water: In home purifying water systems

Beverages: To prevent chlorine taste and chlorination by-products

In food industry: washing fruits and vegetables

Drugs and cosmetics: The standard requires the use of high quality water when creating drugs and cosmetic products

Hospitals: Dialysis, labs and even regular treatment in immune systems patients.

Water reservoirs: To prevent contamination

Sewage purification