Tech Talk

Ultraviolet (UV) radiation is being used increasingly to provide an additional barrier to the passage of pathogens in both water and wastewater treatment plants. While chlorine has been the disinfectant of choice since the early 1900s, the recognition of the protozoan pathogens Cryptosporidium and Giardia as possible contaminants of both water and wastewater has rewritten the rule books. Cryptosporidium and Giardia are not controlled by chlorine at the doses that are typically able to be used in the water industry. They are, however, killed efficiently by UV; however, UV systems have to be carefully specified to ensure the final barrier is effective. Put simply, there needs to be enough UV energy to kill the “bugs”. There is a confusing array of terms and advertising blurb, so this article (UV Disinfection and UV Validation)  is about trying to explain them and allow water utilities to be better informed when considering installation of UV systems.

This article was printed in Water Industry Operator Association journal "Waterworks" in May 2011