AWWA JAW64353

The U.S. Environmental Protection Agency requires validation of the performance of ultraviolet (UV) reactors used by public water systems for controlling pathogens such as Cryptosporidium. U.S. water suppliers validate reactors using coliphage MS2 as the challenge surrogate, but MS2 is significantly more UV-resistant than Cryptosporidium. To identify a surrogate microbe with a UV dose-response similar to that of Cryptosporidium, this research determined the dose-responses of 10 bacteriophages and investigated the stability of the phages in groundwaters in the presence and absence of three UV absorbers. Results indicated that T7 and SP8 demonstrated UV dose-responses nearly identical to that of Cryptosporidium; Q? was more resistant than Cryptosporidium but less so than MS2. Use of a surrogate that has a UV dose-response similar to the target organism offers several advantages, including better estimation of the required reduction equivalent dose; reduction in the required size of UV reactors; and decreased capital, operations, and maintenance costs for utilities. Includes 29 references, tables, figures.