AWWA WQTC52845

Few data are available concerning Cryptosporidium parvum inactivation bychlorine dioxide in natural waters. This study used a cell culture method and in vitro excystation to assess the inactivation kinetics of Cryptosporidium oocysts in three different natural waters (collected post-filtration) and in deionized-distilled water. In addition, the study examined the relationship between easily measured microbial indicators, such as Bacillus subtilis (aerobic) spores and Clostridium sporogenes (anaerobic) spores, and Cryptosporidium parvum oocysts. Finally, oocysts from two different suppliers were evaluated and shown to have marked differences with respect to resistance to chlorine dioxide inactivation. Includes 20 references, tables.