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What is a Filter Press?

Many people, when first encountering a filter press, may ask: What is a filter press and what does it do?

In simple terms, a filter press is a device used to separate solid particles from liquids, especially in large volumes. It is widely used in wastewater treatment processes to remove suspended solids from liquids.

The separation process in a filter press is carried out by applying pressure through a hydraulic jack to a series of plates. This pressure forces the liquid to pass through filter media while the solid particles remain trapped between the plates. The size and capacity of the hydraulic system depend on the number and dimensions of the plates.

Applications of Filter Press

Due to its efficient solid-liquid separation capability, a filter press is used in various industries, including:

Industrial processing plants (hence the term industrial filter press)
Industrial wastewater treatment
Municipal and environmental water treatment systems

The device is particularly useful in applications where moisture reduction is required. Thanks to its pressure-based mechanism, a filter press can remove a significant amount of water from sludge.

Output of a Filter Press

After the filtration process:

The treated water can be reused within the production cycle.
The filter cake (solid residue) is discharged from the system.

The usability of the filter cake depends on the type of wastewater. For example, recent studies have shown that filter cake generated from stone processing wastewater can be reused after further treatment.

Advantages of Using a Filter Press

Using a filter press offers several important benefits, including:

Increased efficiency in wastewater treatment
Reduction in water consumption within production cycles
Lower operational and downtime costs
Optimal water reuse
Reduced energy consumption
Easy operation
Compact footprint suitable for industrial environments
High efficiency in removing suspended solids
Lower installation and operational costs

Compared to traditional sedimentation methods—where production may need to stop for 1–2 months to clean settling ponds—filter press systems enable continuous and simultaneous treatment during production, significantly improving productivity.

Additionally, filter presses play a key role in water conservation and recycling, while producing a smaller volume of solid waste (filter cake), which reduces transportation and disposal costs.

Applications of Filter Press (Detailed)

Filter presses are used in a wide range of industries, such as:

Chemical industries
Food industries, including:
- Syrup production
- Juice production
- Sugar processing
- Beverage manufacturing
- Date extract processing
- Edible oil production

Features of food-grade filter presses:

Made of food-grade stainless steel
Often manually operated depending on capacity
Typically closed-circuit systems
Equipped with drip trays
Use antibacterial and antifungal filter cloths

Water and liquid recycling systems
Pharmaceutical industry
Ceramic and tile industry
Automotive industry (e.g., paint line wastewater treatment)
Refining industry
Metallurgical industry
Mining industry, including:
- Kaolin
- Uranium
- Sand and gravel
- Phosphate and iron
- Zinc, copper, and lead
- Gold, silver, and bronze extraction
Pottery and ceramics production
Industrial oil production
Steel industry
Power generation industry
Brick manufacturing
Paper industry
Laboratory sciences
Agriculture and livestock
Textile and dyeing wastewater treatment
Municipal wastewater treatment
Stone processing industry

How Does a Filter Press Work?

To explain how a filter press works, the following steps can be described:

Filter presses have a number of plates which, after wastewater enters between them, are completely compressed by a hydraulic jack. It should be noted that the wastewater enters the filter press plates after the sedimentation of materials in the treatment tank and after being mixed in the homogenization tank.
The wastewater, which contains mixed solid particles, enters the plates under the pressure of the hydraulic jack activated by the hydraulic unit. The solid particles remain fixed behind the plates and form a cake.

Also, water particles pass through the pores of the filter press cloth membrane. This is where the importance of the filter cloth material becomes evident, because the higher the quality of the filter cloth, the greater its resistance to tension and pressure, and the higher the dewatering efficiency of the cake. It should be noted that, in addition to quality, the cloth material must be suitable for the type of wastewater being processed.

The thickness of the formed cake fills the space between the two plates, and then, with the opening of the jack, the cake is discharged from between the plates.
The vibration system of the filter press also helps in removing the cake from between the plates, and the extracted water returns to the treatment cycle.
In the final stage, the filter press plates are closed again with the re-entry of wastewater into the plates, and this cycle is repeated.

A complete video demonstrating how a filter press works is available at the link opposite.

How a Filter Press is Designed and Manufactured:

It can be said that in the design and construction of a filter press device and wastewater treatment system, steel sheets are widely used. Steel sheets of various sizes, thicknesses, and materials are assembled together to form a steel structure for pressing.

The structure of the filter press is designed in such a way that the Teflon plates can be easily and effectively compressed by the hydraulic jack. After the required pressure is applied by the jack, the valves between the plates create a path for the discharge of water through the channels within the device. It should be noted that these channels are also made of steel sheets.

To design and manufacture a filter press, we must understand the design principles and, with knowledge of the technical specifications and required capacity, proceed with the design and construction of the device. This process requires many years of experience and complete technical knowledge. For full information on how to calculate filter press capacity, click here.

Now, to organize the construction stages of a filter press, they are listed below:

First, the steel and cast components must be designed, prepared, and made ready
Then, the steel components are cut, including the arms of the filter press, and subsequently machined
The frames and plates of the filter press are surface-machined
Then drilling and installation of handles on the plates and frames are carried out
The cast components are ground and also inspected for quality, meaning they undergo quality control
Assembly of the initial and final parts of the filter press and its arms
Construction of the hydraulic unit of the filter press
Installation of the hydraulic unit on the chassis of the filter press
Assembly of the plates on the chassis
Testing of various parts and activation of the hydraulic system
Disassembly of the hydraulic unit and plates
Reassembly of the plates on the filter press chassis
Final testing of the filter press

Determining Filter Press Dimensions:

The important factors that play a role in determining the dimensions of a filter press, ultimately leading to its design and construction, include:

Determining the amount of solid particles present in the wastewater
Determining the number of plates
Determining the dimensions of the plates
The volume of wastewater to be treated, which is reported by the customer

It should be noted that the larger the dimensions of the filter press, the larger cranes are required for its transportation and handling. In the related article on types of cranes, you can review different cranes used for moving filter press equipment.

Types of Filter Press:

Filter presses are categorized based on various criteria, each containing several subcategories. Below, we introduce the different types of filter press. It should be noted that the categories mentioned below can exist simultaneously in a single filter press; for example, an automatic chamber filter press that is both automatic and uses chamber-type plates.

Types of Filter Press Based on Mechanical Operation:
- Manual filter press (small filter press)
- Automatic filter press
Types of Filter Press Based on Plate Type:
- Chamber filter press
- Membrane filter press
- Open-circuit filter press
- Closed-circuit filter press

You may wonder where the hydraulic filter press fits into this classification. It should be noted that the hydraulic system, commonly referred to as a hydraulic filter press, exists in all the types mentioned above, and its operation has already been explained earlier.

Manual Filter Press (Small Filter Press):

Another type of filter press is the manual or small filter press. This type has its own specific features, discussed in detail below. It can be said that manual filter presses are more affordable compared to fully automatic models and are mainly used in small-scale industries with low wastewater volumes, such as laboratories.

Features and Applications of Manual Filter Press:

Lower price compared to other filter presses; considered among the most economical options
Limited applications compared to other types
Suitable for low-capacity wastewater treatment
Operations are performed manually, including:
- Movement of plates
- Opening and closing of plates
- Discharge of solid residues (cake)
Frame materials may include:
- Iron
- Cast iron
- Stainless steel
Lower operating speed due to manual control
Applications include:
- Water treatment
- Pharmaceuticals
- Food industries
- Chemical industries
- Metallurgy and textiles
- Laboratory sciences

Automatic Filter Press:

Common features of automatic filter presses include:

No need for human intervention during operation
High-speed and high-quality performance

Common operations in automatic filter presses:

Movement of plates
Loading and unloading of solids (cake)
Opening and closing of the hydraulic jack
Washing and cleaning of plates for the next cycle

Advantages of Automatic Filter Press:

High efficiency with advanced automation
Maximum adaptability
Reduced filtration cycle time
Maximum dewatering and water recovery
Cost savings due to reduced labor requirements
High safety level
Compliance with international standards

Hydraulic System of Filter Press (Hydraulic Filter Press):

In a hydraulic filter press, pressure for various components is supplied through hydraulic power. These components include:

Main jack
Plate-shifting robot (if installed)
Plate washing system (if installed)

Each filter press includes a hydraulic unit that distributes pressure across these components. Hydraulic pressure is typically generated using fluids such as oil.

Main Jack:

The main jack operates using oil and provides the force required to compress the filter plates. Oil is pumped into the jack, and the resulting pressure compresses the plates, enabling separation of liquid and solid materials.

The hydraulic jack has two movements:

Inward movement (forward stroke)
Outward movement (return stroke)

Pressure and flow rate can be monitored in both directions using control systems within the hydraulic unit.

To ensure proper operation, the required pressure must be maintained consistently throughout the filtration cycle.

The design of the jack, hydraulic unit, and plates are interdependent. Larger plates and stronger feed pumps require higher pressure.

To achieve higher pressure:

A larger jack can be designed
Internal hydraulic pressure can be increased

Plate-Shifting Robot:

This optional system automatically opens the plates. It can operate in two ways:

Using the hydraulic system
Using a robotic mechanism with sensors that continuously monitor its position

The choice depends on design considerations and customer requirements.

Plate Washing System:

This system is synchronized with the plate-shifting robot. As each plate opens, washing nozzles are activated according to a predefined PLC sequence to clean the plates. This system can also utilize hydraulic pressure.

Chamber Filter Press:

A type of filter press with specific plate design differences compared to membrane filter presses, including:

Type of plates used
Compression mechanism of suspensions
Plate arrangement

Membrane Filter Press:

The working principle is explained in detail in the related chamber filter press section.

Open-Circuit Filter Press:

Each plate has its own outlet.

Closed-Circuit Filter Press:

The discharged water is not visible and is collected and discharged as a single stream.

Filter Press Price:

There are many factors involved in determining the price of a filter press. Here, we present 11 practical factors affecting pricing.

The price of a filter press depends on the following factors:

Dimensions and capacity of the filter press
Type of filter press jack
Plate opening and closing system
Number, dimensions, type, and material of plates
Filter cloth material
Electrical panel components
Hydraulic system components
Presence or absence of a drip tray system
Presence or absence of a vibrator system
Open or closed circuit design
Membrane or chamber type filter press
After-sales service and warranty

1. Dimensions and Capacity:

Naturally, the larger the size and capacity of the filter press, the higher its price. To determine capacity, the volume of input materials (including solids and liquids, commonly referred to as slurry or sludge) must be evaluated. The greater the volume, the larger the machine size.

Cake formation time (depending on wastewater type) and operating shift duration also influence capacity.

2. Type of Jack:

Another pricing factor is the type of jack used:

Manual jack
Hydraulic jack

As the size of the filter press increases, the jack must also be larger to provide sufficient pressure, which increases the overall cost.

To calculate jack power, both force and speed parameters must be considered.

Manual Jack:
A mechanical screw-type jack, mainly used in small filter presses. It operates by manual rotation, where gears move the screw and generate motion.

Hydraulic Jack:
Operates using hydraulic pressure and is commonly used in industrial filter presses.

3. Plate Opening and Closing System:

Filter presses can be:

Manual (operated by human force)
Automatic (program-controlled)

This difference significantly affects pricing.

4. Number, Size, and Material of Plates:

Key factors include:

Number of plates
Plate dimensions
Plate material

Plate sizes typically range from 40×40 cm to 2×2 meters. Larger plates result in larger machines and higher prices.

Plate materials include:

Plastic
Fiberglass
Metal

The choice depends on the type of processed material (e.g., metal plates are required in high-temperature oil processing).

5. Filter Cloth Material:

The cloth type depends on the wastewater and filtered material. Common types include:

Cotton
Polyester
Polyamide
Polypropylene

The choice directly affects performance and cost.

6. Electrical Panel Components:

Includes:

Contactor
Thermal switch
Protection systems
Relay
PLC
Pump inverter

Different brands lead to different costs.

7. Hydraulic System Components:

Filter presses can be:

Manual
Automatic
Semi-automatic
Hydraulic

Each type has a different price depending on its configuration.

Used machines often have leakage and technical issues; therefore, purchasing new equipment is recommended for long-term cost savings.

8. Drip Tray System:

Most systems include a drip tray, but it may be optional. Its presence improves water efficiency but increases cost.

9. Manual or Automatic Operation:

The operation mode affects:

Design of the jack
Plate movement mechanism
System speed and efficiency

Automation increases complexity and cost but improves performance.

10. Open or Closed Circuit:

This depends on:

Type of sludge
Plate type
Design considerations
Test results

It directly impacts the final price.

11. Membrane vs. Chamber Type:

Membrane filter presses generally produce drier cake and are more expensive than chamber types due to their advanced performance.

12. After-Sales Service and Warranty:

Warranty duration and type affect pricing
Maintenance and support services should also be considered

Frequently Asked Questions:

Most customer questions arise during operation and vary depending on usage. The best way to get accurate answers is by consulting experts and receiving professional advice.