Frame press dewatering process

The press filter is composed of alternating plates and frames, with filter cloth covering both sides of the plates. A pressing device is used to tightly seal the plates and frames, creating a pressurized filtration chamber between them. At the top center of the plates and frames, small holes are drilled at the same location, which form a passageway upon tightening. Sludge at a pressure of 0.2 to 0.4 MPa enters the filtration chamber through this passageway. The surface of the filter plates is etched with grooves, and the bottom is drilled with channels for the filtrate to exit. Under pressure, the filtrate flows through the filter cloth, along the grooves, and out of the filter machine, thereby dewatering the sludge. Automated plate and frame press filters have been developed both domestically and internationally. These press filters can withstand higher sludge specific resistance than vacuum filters, thereby reducing the consumption of conditioning agents and allowing the use of cheaper chemicals (such as FeSO4·7H2O). When the sludge specific resistance is between 5×10^11 and 8×10^12 m/kg, filtration can be carried out directly without preliminary conditioning. The cake yield and moisture content of the sludge cake should be determined based on test data or similar operating experience. The moisture content of the sludge cake is generally between 75% and 80%.