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Filter presses are essential equipment used for solid-liquid separation in a wide range of industries, including chemical, pharmaceutical, food processing, and wastewater treatment. With over 5,000 units delivered, our company has extensive experience in providing high-performance filter press solutions tailored to various applications. In this comprehensive guide, we explain: ・ What is a filter press and how does it work? ・ What is filter press used for? ・ What types of filter presses are available? ・ Key benefits and applications of filter press systems Whether you're new to filtration technology or looking to upgrade your current system, this page offers valuable insights into choosing the right filter press for your needs.
What is a Filter Press?
Slurry is pumped into the filter press, where it passes through a filter cloth. The solid particles captured on the cloth forms a filter cake, while the liquid (filtrate) is discharged through the outlets. The image on the right shows actual results of filter press's solid-liquid separation using factory wastewater.
Key features of Filter Press
When the Cake Is the Product
When the Filtrate Is the Product
Wastewater TreatmentFilter presses are not only used by companies and facilities that specialize in wastewater treatment, but also by companies that has wet manufacturing processes. Because of their versatility and high performance, filter presses are widely adopted in a broad range of businesses and industries.
Production LineFilter presses are not only used for dewatering, but also play a critical role in product washing processes. In certain manufacturing applications, the presence of impurities within the filter cake can significantly reduce product quality. To address this, cake washing is performed using a filter press to remove residual contaminants. This technique is especially important in industries where high product purity is essential, such as: Pigment Production: to eliminate unwanted by-products that affect color quality and consistency Battery Material Manufacturing: to remove trace impurities that can impact performance and safety.
At the core of a filter press, multiple filter plates are centrally aligned. During operation, slurry—a mixture of solids and liquids—is simultaneously pumped into all the filter plates. Inside each plate, the slurry undergoes a three-step process: filtration, squeeze, and cake wash. All filtrate from the individual filter chambers is collected and discharged through a common outlet line, ensuring efficient and centralized liquid removal. The diagrams below illustrate the internal structure of the filter plates during each process, including slurry input, filtrate discharge, cake washing, and final dewatering.
During the filtration process, slurry is pumped into the filter chamber, initiating the solid-liquid separation process. As filtration progresses, a cake layer gradually forms on the filter cloth inside the chamber. The cake layer acts as a secondary filter by capturing smaller particles that filter cloth can not capture. As the cake layer thickens, chamber pressure is forced to rise. Consequently, the flow rate decreases with the growing resistance. Filtration ends under these conditions: Preset filtration time is reached, the chamber pressure exceeds a defined threshold, or the filtrate discharge volume drops below a specified level.
Each filter chamber is equipped with a diaphragm sheet (also known as a membrane). After cake layer is formed under the initial filtration process, the diaphragm is expanded using air or water pressure. This process is known as diaphragm squeezing, and offers two key benefits : significantly decreased moisture content, which cuts down disposal costs and reduced filtration time, which improves filtration efficiency. Diaphragm squeeze filter presses are especially effective in applications requiring high-efficiency dewatering and low final moisture content, making them ideal for industries such as mining, chemicals, pharmaceuticals, and food processing.
Wash water is supplied into the filter chamber to wash the cake layer. This process helps extract residual ingredients and impurities trapped within the cake, improving product purity and recovery efficiency. There are two main methods for supplying wash water: 1. Washing via Slurry Feed Line Wash water is introduced through the same line as slurry feeding. 2. Washing via Filtrate Outlet Line In this method, wash water is supplied from the filtrate outlet side. It passes through the cake layer in reverse direction and is discharged from the opposite bottom corner of the filter plate.
Filter frames and plates are alternately arranged to facilitate efficient solid-liquid separation. The filter cake is formed within the frames, while the filtrate passes through the filter cloth and is directed out via the grooves in the filter plates.This construction utilizes a corner feed slurry inlet, which significantly improves cake washing efficiency compared to center feed designs. Since this type has separate frames and plates, the number of filter plates increases, leading to higher equipment costs compared to the other types. However, this configuration offers enhanced filtration capacity.
Consists of only plates which forms cavities or filter chambers when they are pressed together. In each chamber, filter cake accumulates between the filter cloths, while the filtrate passes through the cloth and is directed out via the grooves in the filter plates for efficient liquid discharge. Most have a center feed slurry inlet, making it ideal for applications involving raw liquids with big coarse impurities. The large diameter of the center feed port mitigates clogging, even when the slurry contains big coarse particles several millimeters in size.
Alternately arranged membrane plates and non-membrane recessed chamber plates create a filter chamber. During the filtration process, the filter cake forms between the filter cloths. The filtrate flows through the cloth and exits via the grooves in the filter plates. After the filtration, the diaphragm sheets (membrane) expand and apply pressure to the filter cake. This squeezing process compresses and significantly dewaters the cake. Because the system does not rely solely on extended filtration time to achieve dryness, filtration time is shorter and more energy-efficient. Additionally, membrane squeezing provides superior dewatering performance compared to conventional non-squeezing filter presses.
