Inactivation of Hepatitis a Virus and Model Viruses in Water by Free Chlorine and Monochloramine

Abstract

The kinetics and extent of inactivation of hepatitis A virus (HAV) as well as three other viruses, coxsackievirus B5 (CB5) and coliphages MS2 and ϕX174, by 0.5 mg/l free chlorine, pH 6-10, and 10 mg/l monochloramine, pH 8, at 5°C in 0.01 M phosphate buffer were determined. HAV wae relatively sensitive to 0.5 mg/l free chlorine but relatively resistant to 10 mg/l monochloramine. Compared to HAV, CB5 was quite resistant to inactivation by free chlorine but similar in resistance to inactivation by monochloramine. Inactivation of ϕX174 by free chlorine was rapid at pH 6-9 and intermediate between that of HAV and CB5 at pH 10. ϕX174 was inactivated most rapidly of all viruses tested by 10 mg/l monochloramine. Inactivation of MS2 by free chlorine was somewhat more rapid than HAV at low pH but less rapid than HAV at high pH. MS2 inactivation by 10 mg/l monochloramine was slowset of all viruses tested. These reeslts indicate that HAV is inactivated relatively rapidly by free chlorine but relatively slowly by monochloramine. Coliphage MS2 is a reasonable model to predict inactivation of HAV by free chlorine and inactivation of HAV and CB5 by monochloramine. It is a poor model for predicting free chlorine inactivation of CB5 and perhaps some other human enteric viruses.