DISINFECTION OF HUMAN ENTERIC VIRUSES IN WATER BY COPPER-SILVER AND REDUCED LEVELS OF CHLORINE

Electrolytically generated copper:silver ions were evaluated in combination with low levels of chlorine for their ability to reduce the infectivity of hepatitis A virus, human rotavirus, adenovirus and poliovirus seeded in well and tap water. Overall, hepatitis A virus and rotavirus showed less than 2.6 log10 titre reduction for concentrations of 1 mg/l of free chlorine. For free chlorine concentrations of 0.5 mg/l or lower, with or without copper:silver ions, both of these viral strains suffered little inactivation. Poliovirus showed more than 4 log10 titre reduction in the presence of copper: silver combined with 0.5 mg/l of free chlorine, or 1 mg/l of free chlorine alone. Copper:silver ions (700:70 mug/l) reduced the infectivity of poliovirus. Although adenovirus was more efficiently inactivated than rotavirus or hepatitis A virus, it persisted longer than poliovirus under the same treatments, and its infectivity was never completely removed. The addition of copper:silver ions to reduce the levels of free chlorine do not ensure the total elimination of viral pathogens from water systems.