Abstract: An apparatus for dehydrating protein containing aqueous slude, e.g., sludge produced in slaughter houses, which comprises an agglomerator positioned above a filter device, the agglomerator having a bottom wall, a cylindrical outer wall, a cylindrical inner wall, the inner wall and the outer wall providing an annular space therebetween, a sludge inlet duct and a steam inlet duct, the sludge inlet duct and the steam inlet duct communicating with said annular space substantially diametrically opposite each other. The steam is injected in such a way that shear forces will be created in the liquid sludge, thus resulting in an improved precipitation of the proteins of the sludge. The steam is preferably injected tangentially with respect to the outer wall of the agglomerator and the annular space is preferably provided with a helically-extending baffle, the steam inlet extending parallel to the surface of a baffle turn. This provides an excellent precipitation of proteins in a continuous process.