Disinfection of Cryptosporidium parvum with polychromatic UV light

Bench-scale experiments determined the germicidal effects of varying dosage s of polychromatic ultraviolet (UV) radiation on oocysts of Cryptosporidium parvum. C. parvum oocysts suspended in treated surface water were irradiat ed with polychromatic light emitted by either a medium-pressure, continuous -wave UV lamp or a pulsed-UV lamp then assayed with human cell culture tech niques. Experiments conducted using pursed-UV doses of greater than or equa l to 16 mJ/cm(2) provided > 2-log inactivation of suspended oocysts of C. p arvum. Experiments at lower UV dosages established a dose-response relation ship with both the medium-pressure and pulsed-UV lamps. When disinfection r esults from both tight sources were compared on an equivalent dosage basis, no statistical difference in disinfection power was found between the medi um-pressure and pulsed-UV lamps. Results from both lamps showed that UV dos es as low as 7:5 and 11 mJ/cm(2) provided inactivation of infectious oocyst s of C. parvum at rates of 1 log (90%) and 2 log (99%), respectively. The a uthors also examined UV disinfection of heterotrophic bacteria and Escheric hia coli They found the response of heterotrophic bacteria to be statistica lly different from that of C. parvum, whereas E. coli's response to UV ligh t did not statistically differ from that of C. parvum. This suggests that E , coli may be a surrogate organism for C. parvum disinfection provided by U V technologies.