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United States Department of Agriculture

Agricultural Research Service

Title: Chlorine Inactivation of Adenovirus Type 40 and Feline Calicivirus

Authors
item Thurston Enriquez, Jeanette
item Haas, Charles - PHILADELPHIA PA
item Jacangelo, Joseph - LOVETTSVILLE VA
item Gerba, Charles - TUCSON AZ

Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2002
Publication Date: N/A

Interpretive Summary: Disinfection is an important treatment barrier between drinking water consumers and viral gastroenteritis since the small size of enteric viruses may permit their escape from filtration processes. There is little to no information regarding the effectiveness of drinking and wastewater disinfectants (the most widely applied disinfectant is chlorine in the United States) on the inactivation of the enteric adenoviruses and caliciviruses. The free chlorine inactivation kinetics of feline calicivirus (FCV) (closely related surrogate for human caliciviruses), adenovirus type 40 (AD40) and poliovirus type 1 (PV-1) in two water types, at high and low pH and temperature conditions, were determined. Experiments were carried out in buffered demand-free (BDF) and treated groundwater at pH 6 and 8, and 5 and 25 oC. Ct (chlorine concentration multiplied by the contact time) values for each experimental condition were generally higher at pH 8 than pH 6, 5 oC than 25 oC, and for AD40 compared to FCV, although both viruses were very sensitive to free chlorine compared to PV-1. FCV and AD40 were inactivated to 4.34 and 2.54-logs at a free chlorine dose of 0.5 mg/l in BDF water at pH 6 and 5 oC by 15s, whereas 4.04-logs of PV-1 was inativated by 10 min. At pH 8, FCV was inactivated by >4.0-logs between 15s and 3.5 min and 2.54-logs of AD40 was inactivated by 15s. Ct values for 2-log inactivation of dispersed FCV and AD40 in treated groundwater at 15oC were 1.2 and 15.1 times greater than those calculated for experiemnts conducted in BDF water at 5oC. Tailing and low disinfectant decay rates for AD40 disinfected in treated groundwater indicate that aggregation or clumping may have occurred. Low disinfectant residual in the FCV groundwater experiments most likely caused the high Ct values observed in these experiments. The results of this study suggest that conventional drinking water disinfection is sufficient for the inactivation of the studied viruses.

Technical Abstract: Disinfection is an important treatment barrier between drinking water consumers and viral gastroenteritis since the small size of enteric viruses may permit their escape from filtration processes. There is little to no information regarding the effectiveness of drinking and wastewater disinfectants (the most widely applied disinfectant is chlorine in the United States) on the inactivation of the enteric adenoviruses and caliciviruses. The free chlorine inactivation kinetics of feline calicivirus (FCV) (closely related surrogate for human caliciviruses), adenovirus type 40 (AD40) and poliovirus type 1 (PV-1) in two water types, at high and low pH and temperature conditions, were determined. Experiments were carried out in buffered demand-free (BDF) and treated groundwater at pH 6 and 8, and 5 and 25 oC. Ct (chlorine concentration multiplied by the contact time) values for each experimental condition were generally higher at pH 8 than pH 6, 5 oC than 25 oC, and for AD40 compared to FCV, although both viruses were very sensitive to free chlorine compared to PV-1. FCV and AD40 were inactivated to 4.34 and 2.54-logs at a free chlorine dose of 0.5 mg/l in BDF water at pH 6 and 5 oC by 15s, whereas 4.04-logs of PV-1 was inativated by 10 min. At pH 8, FCV was inactivated by >4.0-logs between 15s and 3.5 min and 2.54-logs of AD40 was inactivated by 15s. Ct values for 2-log inactivation of dispersed FCV and AD40 in treated groundwater at 15oC were 1.2 and 15.1 times greater than those calculated for experiemnts conducted in BDF water at 5oC. Tailing and low disinfectant decay rates for AD40 disinfected in treated groundwater indicate that aggregation or clumping may have occurred. Low disinfectant residual in the FCV groundwater experiments most likely caused the high Ct values observed in these experiments. The results of this study suggest that conventional drinking water disinfection is sufficient for the inactivation of the studied viruses.

Last Modified: 12/22/2014
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