Term: sedimentation


The main goal of sedimentation is to remove readily settleable solids and floating materials (not removed in the upstream treatment phases) thus reducing the suspended solids content; so quiet conditions are set up in the sedimentation basin: collected solids are subsequently sent to the sludge treatment processes, and (in case of secondary sedimentation) partially recycled. The sedimentation process takes place in a settling tank, which is a circular or rectangular basins made of concrete or iron, having the bottom lightly sloped towards a zone where the sludge is conveyed by appropriate withdrawal devices.