AWWA WQTC50381

Pilot-scale experiments have been conducted during the winter months at the Britannia Water Purification Plant in Ottawa, Canada. In addition, bench-scale experiments using the source water (Ottawa River water Ontario, Canada) as well as buffered Milli-Q water have been conducted. The data have shown that Bacillus subtilis spores were 1.4 times more susceptible to chlorine dioxide inactivation than Cryptosporidium oocysts. Consequently, Bacillus subtilis spores may be considered as a possible surrogate for Cryptosporidium since they are also resistant to disinfection and yield similar inactivation levels. The impact of physical shearing stress that may be associated with filtration appears to weaken the spores and render them 1.7 times more susceptible to chlorine dioxide inactivation when compared to "non-stressed" spores. Scanning electron microscopy has revealed that filtration appears to damage the surface of the spores and consequently enhances microbial inactivation. Thus, to achieve a desired microbial inactivation level, less chlorine dioxide is required to inactivate "stressed" spores when compared to "non-stressed" spores, and, ultimately, less DBPS may be formed. Work is in progress to compare the data on stressed spores to Cryptosporidium oocysts that have been subjected to the same shearing stress. Includes 14 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

01/01/1999

File Size:

1 file , 260 KB