Abstract: Sewage treatment intended for separating solids and liquids under gravity, particularly for sludge from sewage works, comprising a flat and stationary thickening or drainage grating onto which the sludge is continuously conveyed, this sludge being constantly scraped by a scraping system with flexible blades. The grating is made up of a number of strips, the spacings of which vary along their lengths, the characteristics of the spacings between the strips of the grating and their variations being defined on the basis of the nature of the solid-liquid suspension to the thickened, of its concentration, and of the feed-rate of the plant.

Abstract: Apparatus for dehydrating sludge originating from water purification stations, comprising a draining grid part positioned above a pressing-belt filter part, and a device for washing the grid wherein the device is positioned above the grid, so as to limit the drop height of the flocculated sludge between the grid and the belt, thus avoiding deflocculation of the sludge between the thickening stage and the dehydration stage, the washing of the grid being performed concurrently with the movement of the sludge on the grid.