Have you heard of a filter press but are not sure if it makes sense for your application? This article answers the following questions that you may have: What is a filter press? How does it work? Are there advantages of using them in water treatment? What are the different types of filter presses and their applications?
What is a Filter Press?
As sustainable water treatment becomes more important, filter press filtration offers a powerful and efficient solution. Engineers design filter presses to separate liquids from solids, allowing them to play a crucial role in various sectors, including municipal water treatment, industrial wastewater management, and even food and drug processing. Learning how they work helps reduce operating costs and improve environmental compliance through pressure filtration.
A filter press comprises several key components—namely, filter cloths, plates, a steel frame, hydraulic systems, and manifolds—that work together to achieve efficient solid-liquid separation. To optimize your equipment’s performance and longevity, you need to understand these components.
Filter plates form the chambers where filtration takes place. Filter cloths are a critical component, as they act as the medium through which the filtrate passes while retaining the solids.
The hydraulic system is used to close and open the press, as well as apply the necessary pressure during the filtration cycle. Multiple filter plates are clamped plates together within a steel frame.
This plate stack creates a circuit for the liquid, beginning and ending at the manifold.
How Does It Work?
How does it work? During the fill cycle, the system pumps slurry into the machine and distributes the solids evenly throughout each chamber. This process effectively separates the liquid from the solids.
Filter Cloths and Plates
The filter cloth lies at the core of a filter press filtration system, separating liquid filtrate from suspended solid particles. Initially, fine particles may pass through (fig. 1). Subsequently, larger particles block the cloth’s openings and form a layer that improves filtration efficiency by narrowing the effective pore size (fig. 2). During the feed cycle, the press distributes solids evenly into each chamber. As pressure builds, they compact tightly, which enhances dewatering efficiency (fig. 3).
By the end of the filtration cycle, the filter press fills each chamber completely with dewatered filter cake. The system forms each chamber by clamping two filter plates together and enclosing the cavity in filter cloth. The steel frame holds and aligns the plates, creating a chamber system that defines the press’s total filtration capacity.
Manifold
After the liquid passes through the cloth barrier, the plates feature an inner porting system that delivers filtrate to the manifold. Once filling is complete, the operator adjusts the valves to end the cycle and to direct filtrate out through a single outlet.
When the filtration cycle ends, the follower retracts, and the operator can empty the press. The operator clamps the press to start a new batch.
Many high-capacity filter presses use fast-action automatic plate shifters to speed up cycle times. Manufacturers build some filter presses for fully automatic, 24-hour operation in harsh environments like mining and chemical processing.
Advantages of Using Filter Presses
- High levels of dewatering can be achieved which significantly reduces the volume of waste.
- By producing a dry filter cake, they lower the liquid content in waste streams, helping facilities cut disposal costs and reduce environmental impact.
- Operators can customize filtration precision by selecting the right filter cloths and adjusting operating conditions to meet specific requirements.
- Engineers design filter presses to handle abrasive slurries and perform reliably under harsh conditions.
- The reliable, durable, and modular design of filter presses makes them a versatile and efficient solution for filtration.
Types of Filter Presses and Their Applications
The most common types—plate and frame, recessed chamber, membrane, and automatic—each serve specific applications and operational needs by design.
- A plate and frame press uses alternating plates and frames clamped together to create a series of filtration chambers. Plate and frame presses work well in applications with low solids content and minimal filtration demands.
- Recessed chamber filter presses use recessed plates to form individual filtration chambers. In comparison, recessed chamber systems operate more efficiently and handle higher solids concentrations. For more info see differences between plate and frame and recessed chamber.
- Membrane presses incorporate flexible membranes within the plates to produce drier filter cakes and improve separation efficiency.
- Automatic presses support high-volume operations with minimal manual intervention.
Industries like surface finishing, chemical engineering, battery recycling, bioplastic production, mining, and food and beverage processing all integrate filter presses into their workflows.
Industry demands, application needs, and operational factors determine design elements like filtration capacity, number of chambers, plate size, material selection, and features such as plate shifters, cloth washing system, drip trays, cake shields and safety light curtains. Engineers tailor each filter press design to factors such as filtration cycle time, desired cake dryness, cloth longevity, and the preference for manual or automated plate shifting.
Why M.W. Watermark?
M.W. Watermark® manufactures industry-leading equipment for water and process filtration applications worldwide. Our team offers a wide selection of filter press types, capacities, parts, and accessories to suit different applications. Visit our Filter Presses product page to learn more. Use our custom designed filter press sizing calculator to find the right solution for your application.
Contact our team to explore how we can support your dewatering goals.