Processes for drying sewage sludge and filtering water

摘要

A process for drying and granulating sewage sludge. Wet sewage sludge is dried in either a thermal drying zone or a mechanical dewatering zone comprising a cylindrical chamber having a porous wall and a centrally mounted rotating helical screw conveyor which does not contact the porous wall. A plasticizer is added to the dried sludge and the resultant mixture is extruded to form fertilizer granules. Also disclosed is a process for filtering suspended solids from a water stream using the apparatus of the mechanical dewatering zone.