[Virological analyses of irradiated sewer sludge (author's transl)]

The virus-inactivating effect of Co60 irradiation was verified by a field test in the sewer sludge irradiation plant at Geiselbullach near Munich. The following samples were tested: 16 waste water inlets 15 waste water outlets 32 fresh sludge samples 62 sewer sludge samples prior to irradiation 52 sewer sludge samples and 9 fresh sludge samples after irradiation. We supplemented these analyses by inoculating sewer sludge samples with polio inoculation virus type 1 before irradiation and by the admixing of virus-pure suspensions in MEM + 2 per cent fetal calf serum and virus sludge mixtures packed in plastic capsules with the material to be irradiated. After irradiation these capsules were picked up again and analyzed for their viral content. As test viruses we selected polio wild virus type 1, echovirus type 6, coxsackie virus B5, coxsackie virus A9 and adeno virus type 1. After the sludge samples had been sufficiently homogenized by an adequately long decaying period and provided they contained 3-per cent solid matter, we managed to obtain the same irradiation results in field tests, as with tests under laboratory conditions. For entero viruses the D-value (decimal reduction) was 300 to 400 krad, for adeno viruses it amounted to 700 krad.