Multi-disc screw press for dewatering

Sludge water is carried to the dewatering screw press by using a feed pump. The feed pump pushes sludge water into the first inlet chamber and the flow passes over a weir. Flocculant (polymer) is added, which makes solid particles aggregate into “flock”. This process occurs in the mixing chamber when sludge water is slowly mixed with the flocculant by an adjustable speed bladed shaft. The treated sludge water that is flocked flows by overflow into the screw cylinder, which is the basic mechanism of the press. The variable pitch helix of the screw is completed with plates providing the function of a self-cleaning filter. Fixed plates form the static structure of the grid whereas the moving plates ensure continuous self-cleaning while the screw is in motion. The structure is made of two fixed plates and one loose plate on the guiding rods. The loose plate is designed to rotate while the screw is in motion. The gap between the fixed and loose plates varies from 0.65mm to 0.1mm. Dewatering occurs when the wastewater flows through this gap and the size of the gap continuously changes for optimum dewatering.  A 316 stainless steel spring pressure plate is mounted at the end of the screw which pushes against the solids. This spring keeps constant pressure on end plate. If feed solids vary, the spring will automatically adjust, increasing the dewatering efficiency. Sludge which is discharged from the end of the machine can be transported by means of a belt or screw conveyor. Dewatering substantially reduces sludge volume, thus reducing transportation and disposal costs.