Abstract: A method for dewatering suspensions, in particular communal sewage sludges, in an apparatus comprising a cylindrical filter drum which can be rotated about an axis, a discharge outlet at the opposite end from a feeding inlet and, if desired, in its interior baffles, for example, ring-shaped wier-like obstructions. A conical filter drum which tapers towards the outlet end is fitted to the cylindrical filter drum forming an outlet part. The axis of the drum assembly can be inclined such that the lower contour of the conical outlet part is horizontal or at an acute angle of up to 15.degree. above and/or below the horizontal.

Abstract: A process of dewatering sludge in which raw sludge and a flocculating agent are first mixed by suitable means, then fed into a rotary filter drum or similar device to effect thickening of the sludge and partial dewatering thereof. The now thickened sludge is then conveyed through a filtering assembly in which the sludge is subjected to further dewatering forces, which could be vacuum, centrifugal, static pressure, or pressure while moving along the filter surfaces, thereby further dewatering the sludge. The filtrate discharged from the filter drum and the filtering assembly and also wash water used for cleaning the filter surfaces in the filter drum and the filtering assembly are at least partly returned to the filter drum to effect total flocculation and recapture of sludge particles contained in the filtrate and the wash waters.

Abstract: There is disclosed a process of dewatering sludge and other materials of that kind. The process provides that the raw sludge and a flocculating agent are first mixed by suitable means, then fed into a rotary filter drum or similar device to effect thickening of the sludge and partial dewatering thereof. The now thickened sludge is then conveyed through a filtering assembly in which the sludge is subjected to further dewatering forces, which could be vacuum, centrifugal, static pressure, or pressure while moving along the filter surfaces, thereby further dewatering the sludge. The filtrate discharged from the filter drum and the second filtering assembly and also wash water used for cleaning the filter surfaces in the filter drum and the second filtering assembly are at least partly returned to the filter drum to effect total flocculation and recapture of sludge particles contained in the filtrate and the wash waters.There is also disclosed an installation for carrying out the dewatering process.