A filter press is a high-efficiency filtering equipment that achieves solid-liquid separation through mechanical pressure. It is widely used in sludge dehydration, the chemical industry, food, pharmaceutical, and other fields. Its core working principle can be summarized as a cycle of "feed filtration → pressing dehydration → unloading regeneration". The specific steps are as follows:
1. Pretreatment and feeding stage
The suspension to be separated (such as sludge, slurry) is first pumped to the filter chamber of the filter press. The filter chamber is composed of multiple groups of filter plates (plate and frame type) or integral filter plates (chamber type). Each filter plate is covered with filter cloth (filter medium) on both sides to form a closed filtration space.
2. Preliminary filtration: preliminary separation of solid and liquid
Driven by the pressure of the pump (usually 0.5-1.0MPa), the suspension passes through the filter cloth into the channel between the filter plates, and the solid particles are trapped on the surface of the filter cloth to form a filter cake. The liquid (filtrate) is discharged through the filter cloth to complete the preliminary dehydration. The moisture content of the filter cake is still high at this stage (about 80%-90%).
3. Squeezing and dehydration: deep water removal
After the initial filtration, the hydraulic system of the filter press is started, and the filter plate is pushed toward the center by the piston (the pressure can reach 15-30MPa). The mechanical pressure between the filter plates forces the capillary water and bound water in the filter cake to be further discharged, the volume of the filter cake shrinks, the density increases, and the final moisture content can be reduced to below 60% (some models even reach 40%).
4. Unloading and regeneration
After the dehydration is completed, the hydraulic system is depressurized, and the filter plates are pulled apart piece by piece. The dry filter cake falls off due to its own weight or mechanical assistance, and the unloading is completed. Subsequently, the filter cloth is cleaned of residual particles by a high-pressure water gun or an automatic cleaning device, and the filtering performance is restored to enter the next cycle.
Core advantages: Through the dual mechanism of "mechanical pressure + filter cloth interception", the filter press can achieve efficient solid-liquid separation, especially suitable for deep dehydration of high-viscosity and fine-particle materials (such as municipal sludge and chemical residues), and is a key equipment for industrial wastewater treatment and resource recovery.
