[Chlorinated hydrocarbons in sewage sludge from a plant in Oslo (author's transl)].

Samples of sewage sludge from a plant in Oslo were analysed by gaschromatography for persistent chlorinated hydrocarbons. Polychlorinated bifenyls (PCBs) were found in all samples. In 1972 the mean value was 0.9 +/- 0.24 ppm PCBs, while the corresponding value two years later was 0.3 +/- 0.14 ppm. It is suggested that the observed decrease is connected with the restrictions of industrial use of PCBs from 1973. The samples from 1974 were also analysed for phtalic acid esters. Residues of dimethyl-(DMP), diethyl-(DEP), dibutyl-(DBP) and diethylhexcyl-phtalate (DEHP) were found. Mean concentrations of DEHP and DBP were found to be 27 and 13 ppm respectively. The effect of the sludge treatment on PCBs was tested by comparing sewage coming into the plant with cleaned water leaving the plant. Between 50 and 85 percent of total PCBs remained in the water after the cleaning process. The total amount of PCBs in the sewage sludge per year was calculated to be about 2 kg.