FATE OF HUMAN ENTERIC VIRUSES (ROTAVIRUSES AND ENTEROVIRUSES) IN SEWAGE AFTER PRIMARY SEDIMENTATION

A wastewater treatment plant, which treats sewage by either mechanical primary sedimentation or lime coagulation, was used for modeling the fate of human enteric ciruses after these treatments. The occurrence of human rotaviruses and enteroviruses was monitored in sewage influent, effluent and sludge samples. The level of indigenous enteric viruses in raw sewage was very high (up to 10,000 I. U. /1); the values for rotavirus and enterovirus were of the same magnitude, although no correlation was found between the levels of both kinds of human enteric viruses. Both rotaviruses and enteroviruses were removed from sewage and transferred to sludge at similar rates after mechanical sedimentation, although rotaviruses were more efficiently recovered from sludge samples than enteroviruses. After chemical coagulation by lime treatment, most human enteric viruses in sludge were inactivated. Lime coagulation should be regarded as a most effective single-step treatment for the removal of viral pathogens such as rotaviruses and enteroviruses from sewage.