DISINFECTION
This is the most common application of UV light in water treatment. A properly sized UV system is designed to meet a minimum of 3 Log reduction a minimum of 30,000 micro-watt seconds (or 30mJ/cm2) at one year, the end-of-lamp life (EOL). Some typical locations of installation would be after filtration.
CHLORINE/CHLORAMINES DESTRUCTION
Bathers introduce organics to the water, such as bacteria, urine, sweat and other excretion products. Swimming pool water must undergo treatment, in order to remain clear and clean, free from harmful substances, bacteria, viruses, algae and other pathogens and suitable for use by swimmers. This necessitates the need for disinfectants such as chlorine to be added to the water to inactivate pathogenic microorganisms. Sweat and urine largely consist of water, ammonia and urea. When these products react with chlorine, unwanted reaction by-products can be formed which consist mainly of chloramines. Of particular concern in swimming pool waters are the formation of chloramines and chlorinated organic compounds that are known to give rise to swimming pool odor and eye, nose and throat irritation.
While the addition of chlorine and chloramines to pool water may control bacteria levels, there is growing awareness regarding the negative health impacts of chlorine and its by-products. On the other hand, unlike bacterial pathogens, Cryptosporidium oocysts are resistant to chlorine disinfection and can survive for days in treated recreational water venues despite adherence to recommended residual chlorine levels (1–3ppm). A UV system sized for chloramines reduction (60mJ/cm2) delivers sufficient UV dosage to inactivate Cryptosporidium. UV systems can also significantly reduce the microbial counts by destroying at least 99.9% of the bacteria present in the influent stream, when installed after filtration.