[Virus removal from municipal wastewater by biological sewage treatment]

During a period of ten months, we have determined once a week the amount of viruses in the untreated sewage and in the effluent of two communal sewage treatment plants. Besides, we have compared the virus content of chlorinated and unchlorinated effluent and have determined the amount of viruses in the river in which the effluent is discharged, and in groundwater. In order to concentrate the viruses, the AlCl3-treated samples were filtered through cellulose nitrate filters and the adsorbed viruses eluted with cell culture medium containing 10% fetal calf serum. This medium was used for inoculating cell cultures which were monitored several times weekly for CPE. After the treatment in the plants, the number of viruses was reduced 99.15 and 97.9% respectively. Chlorination of the effluent further reduced the number of viruses by a factor of 5. None of the groundwater samples was viruspositive.