[Sewer sediments--for the detection of the heavy metal containing waste water flow into sewer systems]

Increased heavy metal content often prevents agricultural application of sewage sludge. The identification of a singular pollutant requires time-consuming and cost intensive investigations. A gridlike investigation of sewer sediments offers an effective tool for the identification of heavy metal pollutants--even if the discharge of sewage occurs by batch processes. For the sewer sediments enrich the heavy metals during longer periods. By means of this methodology we succeeded in lowering the cadmium concentration of the sewage sludge within 3 months from 40 to 5 mg/kg DS and to enable its agricultural application.