Inactivation of Cryptosporidium parvum oocysts with ozone and monochloramine at low temperature.
The rate of Cryptosporidium parvum inactivation decreased with decreasing temperature (1-20 degrees C) for ozone and for monochloramine applied alone as well as after pre-treatment with ozone. Synergy was observed at all temperatures studied for the ozone/monochloramine sequential disinfection scheme. The synergistic effect was found to increase with decreasing temperature. The inactivation rate with monochloramine after ozone pre-treatment was 5 times faster at 20 degrees C and 22 times faster at 1 degree C than the corresponding post-lag phase rates of inactivation with monochloramine at these temperatures when no ozone pre-treatment was applied. The CT required for achieving 2-logs of inactivation ranged from 11,400 mg min l-1 at 20 degrees C to 64,600 mg min l-1 at 1 degree C when monochloramine was applied alone. In contrast, the CT required for an overall sequential inactivation of 2-logs ranged from 721 mg min l-1 at 20 degrees C to 1350 mg min l-1 at 1 degree C when applying monochloramine after ozone pre-treatment. The presence of excess ammonia in the monochloramine solutions was not responsible for the synergy observed in ozone/monochloramine sequential disinfection.
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL 61801, USA.
A M
AM
Driedger
J L
JL
Rennecker
B J
BJ
Mariñas
D000818:Animals; D002417:Cattle; D002700:Chloramines / Q000494:pharmacology*; D003080:Cold Temperature; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000502:physiology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods; D004357:Drug Synergism; D010126:Ozone / Q000494:pharmacology*; D013696:Temperature; D014867:Water / Q000469:parasitology*; D014881:Water Supply / Q000592:standards*
D002700:Chloramines; D004202:Disinfectants; D014867:Water; D010126:Ozone; C030816:chloramine