In the second part of the screen the volume of material between the screw flights is reduced by the conical screw and the sludge pressed against the inner screen surface so that the sludge is dewatered, with a continuous reduction of the filter cake thickness. The screen apertures are much smaller in this screen section.

In the third part of the screen the residual water is pressed out of the sludge, at a minimum filter cake thickness, by the pneumatic counterpressure cone at the press discharge. The dewatered sludge is pushed by the conveying screw past the pressure cone into the discharge chamber. The sludge residence time in the screw press and thus the filtration time can be adjusted to individual requirements by adjusting the rotational speed of the screw shaft.

Dewatering of thin sludges

Due to pump feeding, large volumes of sludge water are removed already in the pre-dewatering zone. This permits cost-efficient dewatering of thin sludges with a solids concentration < 1%. This application allows typical dewatering results of 18 – 25% DS and achieves a sludge volume reduction up to > 97% in a single step!

Variable sludge characteristics

Dewatering performance is usually impaired and operator attention increased by frequently varying sludge quality. Our HUBER Screw Press Q-PRESS® automatically selfadjusts to over- and underloading. A control loop makes sure that optimal operation is always maintained, with minimised operator attention.