|Thurston Enriquez, Jeanette|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2004
Publication Date: 6/1/2005
Citation: Thurston Enriquez, J.A., Haas, C., Jacangelo, J., Gerba, C. 2005. Inactivation of enteric adenovirus and feline calicivirus by chlorine dioxide. Applied and Environmental Microbiology 71:3100-3105. Interpretive Summary: Chlorine dioxide is an alternative to chlorine for disinfection of drinking water. Advantages of chlorine dioxide include its ability to effectively reduce pathogenic microorganisms at a wide water pH range, provides a relatively persistent disinfectant residual in treated water, and reduces tastes and odors caused by organic and sulfurous compounds. While studies have shown that chlorine dioxide is effective at the reduction of several pathogens in water, limited information is available concerning the reduction of emerging viral pathogens. Caliciviruses and enteric adenoviruses are important causes of viral gastroenteritis. Chlorine dioxide inactivation experiments were conducted with enteric adenovirus type 40 (AD40) and feline calicivirus (FCV). FCV served as a surrogate for human caliciviruses. Experiments were carried out in buffered disinfectant demand free water at high and low pH and temperature conditions. From the results of this study, AD40 and FCV would be inactivated by commonly applied chlorine dioxide concentrations and contact times applied for drinking water treatment in the United States.
Technical Abstract: Chlorine dioxide inactivation experiments were conducted with adenovirus type 40 (AD40) and feline calicivirus (FCV). Experiments were carried out in buffered disinfectant demand free water at high and low pH and temperature conditions. Ct values, concentration of chlorine dioxide multiplied by contact time with virus, were calculated directly from bench-scale chlorine dioxide inactivation experiments and from application of the Efficiency Factor Hom (EFH) model. Ct values for 4-log (99.99%) inactivation of AD40 at 5 oC and pH 6 and 8 were 0.83 and 0.47 mg/L x min, respectively. Ct values for FCV at 5 oC and pH 6 and 8 were 4.05 and 0.47 mg/liter ´ min, respectively. For each experimental condition, Ct values were significantly higher at pH 6 than pH 8, and at 5 oC compared to 15 oC. For FCV and AD40 experiments conducted at 5 oC and pH 6, Ct values were 1.8 and 8.6 times higher compared to experiments carried out at pH 8. Ct values for 4-log inactivation of AD40 and FCV by chlorine dioxide at 5 oC were 1.9 and 2.0 times higher than Ct values calculated for disinfection experiments conducted at 15 oC. Ct values listed in the United States Environmental Protection Agency (USEPA) Guidance Manual were higher than Ct values generated by this study. Therefore, AD40 and FCV would be inactivated by commonly applied chlorine dioxide concentrations and contact times applied for drinking water treatment in the United States.