Voest-alpine Aktiengesellschaaft

Fritz Ludewig

Walter Lugscheider

Alois Janusch

In a process for the disposal of settled sludge derived from a biological sewage-disposal plant, in which the thickened sludge is further dewatered and at least partially thermically decomposed within a centrifuge (15) by using separated steam, preferably at a pressure within the range of 1 to 15 bar and at a temperature of 100.degree. C. to 200.degree. C., the centrifugate of the centrifuge (15) subjected to the action of saturated steam is discharged via a lock (18) and is immediately subsequently subjected to a sulfidic precipitation (19) of heavy metals. The solid matter separated within the centrifuge (15) is simultaneously discharged via locks (28) and optionally is subjected to a post-drying step (33) and at least partially to a combustion, for example a fluidized bed combustion (23), for steam production (17) for the centrifuge (15), noting that the steam is completely circulated along a closed circuit and the waste steam of the locks is used for air-heating (30), whereupon condensate formed is supplied to the pre-settling basin (5) of the sewage-disposal plant, whereby the energy requirement is reduced and the environmental load is equally reduced.

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Leoben, Austria

Fritz Ludewig