What is a filter press and how does it work
A filter press consists of a series of filter plates covered with filter cloth, mounted in a sturdy frame. Plates are held together under high pressure by a hydraulic system, forming closed chambers between each pair of plates. The suspension to be filtered is pumped into these chambers, where liquid passes through the filter cloth while solids are retained forming a compact cake.
The filtration process in a filter press follows several sequential stages:
Chamber filling - suspension is pumped at moderate pressure into filtration chambers. Liquid begins passing through the filter cloth from the moment it contacts it, depositing the first solids that form the initial filter layer.
Main filtration - as chambers fill and the solids cake grows, resistance increases and higher pumping pressure is required. This phase continues until chambers are completely filled with solid cake or until filtrate flow falls below an economic value.
Compression (in membrane filters) - in membrane filter presses, once filtration is complete, flexible membranes integrated in the plates are inflated with high-pressure air or water, compressing the cake and expelling additional liquid. This produces significantly drier cakes.
Air blow (optional) - compressed air can be blown through the cake to displace residual liquid from pores, increasing final dryness.
Discharge - the hydraulic system releases pressure and plates separate, allowing solid cakes to fall by gravity or be removed manually.
Filter press efficiency depends on several factors: suspension characteristics (solids concentration, particle size, compressibility), filter cloth type, operating pressure, and plate design. Modern filter presses can operate at pressures up to 15-16 bar, producing cakes with dry solids contents exceeding 60% for many materials.
Applications of filter presses
Wastewater Treatment
Filter presses are fundamental equipment in water treatment plants for dewatering biological sludge produced in secondary treatment, where they reduce sludge volumes by over 90%; dewatering chemical sludge from flocculation and precipitation processes; treating industrial effluents with high solids content; and preparing sludge for final disposal or incineration. Membrane filter presses are especially valued for their ability to produce very dry cakes that reduce transport and disposal costs. Andritz is world leader in filter presses for water treatment applications.
Mining Industry
In mining, filter presses process mineral concentrates for dewatering before transport or further processing; tailings and mining residues for water recovery and volume reduction; mineral suspensions for value recovery; and flotation sludges. Filter presses in mining must handle highly abrasive materials and large volumes, requiring robust construction with wear-resistant materials.
Chemical Industry
Filter presses find extensive application in chemical industry for recovery of valuable crystallized and precipitated products, catalyst and process material dewatering, separation of chemical synthesis products, chemical waste stream treatment, and production of pigments and specialty chemicals. For corrosive materials, filter presses built with reinforced polypropylene plates, special coatings or materials like PVDF are available.
Food Industry
In food, filter presses process juice and wine clarification sludges, beer and distillery production residues, fruit and vegetable processing byproducts, and oil and fat clarification. Equipment for food applications requires hygienic design, food-contact approved materials, and ease of cleaning.
Pharmaceutical Industry
Filter presses in pharmaceuticals are used for crystallized active ingredient recovery, biomass separation from fermentation broths, and intermediate product dewatering. Pharmaceutical equipment requires high-quality stainless steel construction, polished surfaces, and design facilitating cleaning and cGMP validation.
Types of filter presses available at Foeth
Plate and Frame Filter Presses
The classic design where solid plates alternate with hollow frames forming filtration chambers. Filter cloths are placed on plate faces. This design offers good accessibility for cleaning and cloth changes, and is suitable for a wide variety of applications. It is especially common in chemical and product recovery applications.
Recessed Plate Filter Presses
Filtration chambers are formed by cavities machined in faces of solid plates that face each other. This design is structurally more robust than plate and frame, allowing higher pressure operation. It is the most common design in water treatment and mining applications where high productivity is required.
Membrane Filter Presses
Incorporate flexible elastomer or polypropylene membranes in plates that can be inflated after filtration to compress the cake. This additional compression can increase dry solids content by 5-15 percentage points compared to conventional filter presses. They are the preferred choice when minimizing cake moisture is critical for reducing disposal costs or when recovered liquid value justifies additional investment. Andritz is leader in membrane filter press technology.
Automatic Filter Presses
Equipped with automatic plate separation and cake discharge systems, significantly reducing manual intervention and cycle times. They are ideal for high-capacity operations and where continuous operation with minimal supervision is required. Some models include automatic cloth washing.
Belt Filter Presses
Although technically different from plate filter presses, belt filters are continuous dewatering equipment using two filter belts that compress sludge between them. They are especially common in municipal water treatment for dewatering large sludge volumes.
Renowned manufacturers in Foeth's portfolio
Andritz Separation
Andritz is world leader in solid-liquid separation technology, offering a complete range of filter presses for all industries. Their equipment is recognized for advanced membrane technology producing very dry cakes, robust construction for demanding industrial applications, state-of-the-art automation and control systems, and extensive experience in water treatment, mining, chemical and food applications. Andritz has installed thousands of filter presses worldwide and continues leading innovation in energy efficiency and automation.
BHS Sonthofen
BHS Sonthofen is a German manufacturer recognized for high-quality filter presses for chemical and pharmaceutical industry. Their equipment stands out for German precision engineering, high-quality stainless steel construction for demanding applications, design oriented toward ease of operation and maintenance, and experience in specialty chemical and pharmaceutical applications.
MES Filterpressen
MES Filterpressen is a manufacturer specialized in filter presses for diverse industrial applications. Known for equipment with good value for money, robust construction for extended industrial service, and solutions adapted to specific process needs.
Why buy used filter presses from Foeth
Largest warehouse in Europe
Foeth has Europe's largest warehouse of used process machinery, with approximately 2800 machines available. Our filter press inventory includes equipment from Andritz, BHS Sonthofen, MES Filterpressen and other recognized manufacturers, in various sizes and configurations. Inventory is updated weekly with new acquisitions.
Proven machines from recognized manufacturers
We offer filter presses from manufacturers established for their quality and durability. Each machine is mechanically inspected by our technical team, verifying plate condition, frame, hydraulic system, pumps and control systems. This inspection ensures equipment in verified operating condition.
Worldwide export with experience
We regularly export machinery to customers on all continents. Our team manages logistics for large and heavy equipment, export documentation and transport coordination to deliver your filter press in perfect condition.
Significant savings with immediate availability
Used filter presses from recognized brands represent a significant fraction of new equipment cost, with immediate availability from stock. Filter presses are robust equipment with few moving parts, designed for decades of service. Filter cloths and seals are consumables replaced regularly regardless of whether equipment is new or used.
Related machine categories
Besides filter presses, Foeth offers a wide range of separation and filtration equipment:
Industrial filters - complete range of filtration systems
Industrial centrifuges - separation by centrifugal force
Decanters - continuous sludge dewatering
Candle filters - liquid filtration
Industrial mixers - homogenization systems
Storage tanks - liquid and solid storage
How to purchase a filter press at Foeth
Browse current catalog
Our online catalog is updated weekly with new acquisitions. Check currently available filter presses to see detailed technical specifications, photographs and capacities of each machine in stock.
Request technical information
If you need additional information about a specific filter press or advice on which model best suits your application, our technical team is available to answer your queries.
Receive a no-obligation quotation
Contact our team to receive a quotation for the filter press you're interested in. We prepare detailed offers including transport options.
If you don't find the right machine
Our purchasing team has an extensive international network and can search for filter presses with particular specifications especially for you.
Start cooperation - send inquiry or browse filter press catalog!
