ENTERIC VIRUSES IN A WASTE-WATER TREATMENT-PLANT IN ROME

Over the course of a year a series of samples were taken from a wastew ater treatment plant handling domestic sewage at each stages of the pr ocess, to detect the presence of enteric viral and classical bacterial indicators, and physicochemical parameters. The viruses were isolated on BGM cell cultures and counted according to the Most Probable Numbe r method. The values of enteric viruses varied from 10(2) to 10(4)/L i n raw sewage and from 10(0) to 10(3) in final effluent. The efficiency of the plant at each stages during processing was evaluated. The para meters analysed show a systematic reduction of values between input an d output, with average bacteriological reductions of 88% (fecal strept ococci), 93% (fecal coliforms) and 94% (total coliforms), viral load r educed by 0-99%. COD and suspended solids showed a reduction of 61% an d 71% respectively. The 40% of isolated viruses were submitted to iden tification procedures using molecular techniques and pools of antisera . The viral types identified were enteroviruses (poliovirus and coxsac kievirus B) and reoviruses. Viruses appear less easily removed than cl assical bacterial indicators. Reoviruses were removed less efficiently than enteroviruses.