AWWA JAW59538

Ultraviolet (UV) light technology is gaining ground as an effective and inexpensive disinfectant for control of Cryptosporidium in drinking water. Previous researchers examining the effects of UV have focused only on UV inactivation of Iowa strain oocysts. However, to accurately assess the technology's efficacy and applicability to drinking water treatment, more information was needed on the UV dose-response of other Cryptosporidium strains infectious to humans. This study investigated the effect of UV doses ranging from 5 to 40 mJ/cm² on five strains of C. parvum - Iowa, Moredun, Texas A&M University, Maine, and Glasgow. Results indicated that all five strains of C. parvum were highly susceptible to low levels of UV light. A UV light dose as low as 10 mJ/cm² achieved at least 4-log₁₀ inactivation for all strains evaluated, and most strains were susceptible at even lower UV doses, e.g., 2-5 mJ/cm². With the promulgation of new regulations by the US Environmental Protection Agency, UV is moving ahead as a best available technology for controlling Cryptosporidium oocysts in drinking water supplies. The results of this study give utility managers a greater understanding of and increased confidence in UV treatment for inactivation of a variety of Cryptosporidium strains. Includes 64 references, tables, figures.