Synergistic inactivation of Cryptosporidium parvum using ozone followed by monochloramine in two natural waters.
The effect of sequential exposure to ozone followed by monochloramine on inactivation of Cryptosporidium parvum oocysts suspended in untreated natural surface water from two different sources was studied in bench-scale batch reactors. Animal infectivity using neonatal CD-1 mice was used to measure oocyst inactivation. A statistically significant synergistic effect on oocyst inactivation was measured in both natural water samples studied. The magnitude of the effect measured in the natural water with lower turbidity, colour, and organic carbon concentration was comparable to that previously reported for oocysts suspended in buffered de-ionized water but was reduced considerably in the natural water with higher turbidity, colour and organic carbon concentration. Synergy increased with initial pH and with the degree of ozone pre-treatment but was independent of temperature. For water treatment plants with adequate disinfectant contact times, ozone followed by monochloramine may be a practical means of achieving additional C. parvum inactivation, however, the influence of water quality characteristics should be considered.
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alta., Canada T6G 2W2.
Kaushik
K
Biswas
Stephen
S
Craik
Daniel W
DW
Smith
Miodrag
M
Belosevic
D000818:Animals; D002244:Carbon / Q000032:analysis / Q000737:chemistry; D002700:Chloramines / Q000737:chemistry / Q000494:pharmacology*; D016785:Cryptosporidium parvum / Q000187:drug effects*; D004203:Disinfection / Q000379:methods*; D004357:Drug Synergism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D051379:Mice; D009391:Nephelometry and Turbidimetry; D009930:Organic Chemicals / Q000032:analysis; D010126:Ozone / Q000494:pharmacology*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods
D002700:Chloramines; D009930:Organic Chemicals; D010126:Ozone; D002244:Carbon; C030816:chloramine