Belt press，also named belt type sludge dehydrator，is to realize solid liquid separation which rely on the tension of two upper and lower filter belts to form the pressing and shearing force of the sludge layer. It belongs to the 24-hour continuous running device and has a large processing capacity; the sludge has a high water content and a relatively large water consumption. It is generally used in large sewage treatment plants.
Screw Press，named Fold Screw Sludge Dehydrator, which achieves the purpose of solid-liquid separation by the principle of screw extrusion. It is also a 24-hour continuous running device. Compared with the belt press, the sludge moisture content is similar, but the energy consumption is lower, and it is specialized used in oily sludge treatment.
Filter Press relies on the pressing device to press the filter plate, and then the suspension is pumped into the filter chamber, and the filter cloth is used to intercept the solid particles and simultaneously discharge the filtrate to achieve the purpose of solid-liquid separation. Its working is in intermittent Pressure filtration , and Compared with the belt press，the processing capacity is smaller ; it is generally used for sludge dewatering in factories, and is suitable for applications where the solid water content is low.