How Does Ultraviolet (UV) Work?
Disinfection may be accomplished by chemical or physical methods. However, an increased awareness of the many disadvantages of chemical disinfectants; especially the most common, chlorine, leads many wastewater engineers to search for a non-chemical means. The solution to this quest is both energy and cost efficient ultraviolet systems. These systems embody many attractive features and benefits.
Ultraviolet light provides a physical process for the disinfection of water and wastewater without the disadvantages associated with chemical disinfection. UV either kills microorganisms or inactivates their reproductive capability - effectively disinfecting wastewater effluent. In the process of disinfecting with UV, wastewater flows past specially engineered light bulbs, which emit ultraviolet light energy. This form of treatment reduces free chlorine levels required up to 99%.
UV offers an alternative, which is successfully practiced without adding any negative consequences. Ultraviolet light; energy found naturally in sunlight, is within the electromagnetic spectrum. The light emitted by these units is in the range between 200-300 nano-meters which is widely known to be lethal to harmful microorganisms. By disrupting the reproductive mechanism (DNA) of bacteria, viruses, yeasts and molds and algae, the organisms are inactivated, thereby making this process extremely useful in eliminating agents of disease, spoilage and biological growth.
On site wastewater treatment plants generally require some form of disinfection in order to meet specific regulated bacterial limits before discharging to surface waters. The main objective of disinfection is to reduce the number of waterborne pathogens downstream to safe levels and thereby lowering the risk of exposing people to infectious disease. The persistence of some pathogens in receiving waters and soils indicates that disinfection of wastewater effluents must provide the first line of defense for drinking water from surface or ground sources. To meet this objective, the disinfectant must inactivate a wide range of bacteria and virus in a variety of water and wastewater variations.