1. Why are two different wavelengths used in water treatment?

Two different UV wavelengths are employed in water treatment 254 and 185 nm. 254 nm UV light is called the germicidal light because of its ability to destroy microorganisms. It is used to disinfect and to destroy ozone. It penetrates the outer cell wall of the microorganism, passes through the cell body, reaches the DNA and alters the genetic material, destroying the organism.  The 185 nm light carries more energy than the 254 nm light. It generates hydroxyl (OH·) free radicals by cleavage of the water molecules, and is used in TOC reduction to decompose organic molecules into carbon dioxide and water.

2 .Describe a typical UV water treatment unit and how it works.

A typical UV unit works by irradiating flowing water using UV lamps strategically placed within the treatment chamber. Although the water resides within the chamber for only a few seconds, it receives sufficient UV dosage to be lethal to microorganisms present in the feed water. A dosage of 30 mJ/cm2 is more t han sufficient to destroy most water-borne microorganisms. UV treatment requires only a fraction of the contact time required by other disinfection methods.

3. What are the primary benefits of ultraviolet water treatment?

Ultraviolet (UV) light treatment is a widely recognized and proven method of disinfection of water. It is a physical treatment, not chemical, so it doesn't alter the water chemistry. UV adds nothing to the water such as undesirable color, odor, taste or flavor and neither does it generate harmful by-products.

4. What industries use UV water treatment?

It is a well-proven technology and pretty much every industry that utilizes water for process or production could employ UV technology for water treatment. Examples include microelectronics, life sciences, food & beverage, recreational water, drinking water, etc.