Ultraviolet (UV) is a range of wavelength of energy which forms part of the electromagnetic spectrum. UV “light” lies between x-ray waves and the wavelength that we call visible light. UV light cannot be perceived, but forms part of the sun’s radiation and is the reason we experience sunburn. Ultraviolet systems emit UV light which causes fatal damage to the genetic core of microorganisms, being absorbed by the cells of the microbe and preventing cell enzymes from interpreting the DNA. This prevents the microorganism from functioning and, most importantly, reproducing. The process is extremely effective and has been estimated to cause the destruction of 99.99% of pathogenic microorganisms.
The UV light must be of high quality and of the right wavelength. Furthermore it is critical that there be a decent contact between the light and target organisms in order to accomplish the desired level of disinfection. The UV exposure must therefore be sized according to the desired application. UV disinfection should be the very last stage of an industrial filtration process to ensure the early removal of particles which may be present in the feed water supply and which may act to shield the microorganisms from the damaging effects of the UV rays. In order that UV system should work effectively, input water must exclude particles any larger than 5 microns.
UV has been recognised as a method of purification since 1996, and has been characterised as an effective method of disinfection. UV purification systems offer various advantages over traditional water treatment technologies. They are safe and effective and do not alter the taste of the water. Furthermore, the use of a UV purification system in industrial filters does not affect the pH level or mineral properties of the water. Perhaps most importantly, it works without the introduction of chemicals to the water and therefore eliminates the need for extensive post-filtration to remove harmful chemicals.
Various agents can contribute to the successful disinfection of water. Where UV systems are concerned, the success of the process is dependent on the correct method of exposure, including a sufficient intensity of UV light and an adequate length of time. It is important to note that using input water which fails to meet the general guidelines for water quality will certainly have a negative effect on the system’s effectiveness.