Sludge Dewatering press

Multi-Desk Screw Press

Dewatering press (Sludge Dehydrator):

1.Working principle and main structure

Sludge Dewatering press (sludge dehydrator) is composed of screw body, driving device, filtrate receiver, mixing system and frame. When the dewatering machine operates, sludge will be transported to the mixing tank by sludge feed pump, at the same time, the solid polymer has been added to the mixing tank quantitatively by the polymer feed pump. Mixing motor drives the whole mixing system to make the sludge and polymer fully mixed and then flocs will be produced. When the liquid level arrives at the superior level of the liquid level sensor, the liquid level sensor gets the signal to make the motor of screw body operates, then begins to press the sludge which has flows into the screw body. Sludge will be transported to the outlet step by step by the effect of screw shaft; filtrate will flow out by the space of fixed annular plates and moveable annular plates.

In general, Sludge Dewatering press which uses the screw extrusion principle is a new type of solid-liquid separation device. It reaches the goal of extrusion dewatering sludge by the powerful extrusion pressure of changing the screw diameter and distance, and the tiny spacing between moveable annular plates and fixed annular plates.

1.1 Screw body

Screw body is composed of fixed annular plates, moveable annular plates, screw shaft, screw, gasket and lots of junction plate. Fixed annular plates are connected by six screws, gasket and moveable annular plate are assembled between fixed annular plates, the fixed annular plates and moveable annular plates are made of wearable material which makes the service life of the whole machine longer. Screw shaft passes through the fixed annular plates and moveable annular plates, and the moveable annular plates do not contact the screw shaft.

The Sludge Dewatering press, made of multiple fixed annular plates and moveable annular plates with the screw shaft running through it, is a filter device. The front part of the main body is the thickening part, and the ending part is dewatering part. So the thickening and dewatering of the sludge can be finished in one canister. It can thicken and dewater sludge in one box, and has taken place of the traditional filter clothes and centrifugal filtration method for its distinctive filter model. Sludge will be transported to the dewatering department after being thickened in the thickening department. In the advancing process, great pressure has been produced because of the gradually decreasing filter spacing and screw distance, and the back platen clogging. Then the volume decreases continuously, and the purpose of fully dewatering will be achieved.

1.2 Driving device

Drive device is the power source of the equipment, and the performance of drive device can affect the equipment performance directly. For this reason, the motor our company adopts has a superior performance with IP55 and F level. The motor conforms to the standard of IEC, and the power is as request.

Frequency conversion starting and speed control mode can suit for different application conditions to avoid the impact of the load.

1.3 Filtrate receiver

Filtrate receiver, welded by plate, is used to collect filtrate pressed by screw body. Filtrate receiver is welded to the side plates directly, and there are flanges on the side to connect the external devices.

1.4 Mixing system

The mixing system is used to make the sludge and polymer fully mixed, and the formed flocs will be transported to the screw body to press and dewater.

There are sludge inlet, overflow port, polymer feed port and vent nozzle in mixing tank. Also there is the level adjusting device to adjust the sludge inleting amount.

1.5 Frame

Frame is welded by structural steel, and the whole welding effect and steel performance are good. There are lifting devices on the frame which make the transportation and lifting more convenient.

2. Sludge is first fed into the flow control tank and then it flows down into the flocculation tank, where the polymer coagulant is added.


3. From there, the flocculated sludge overflows into the dewatering drum where it is filtered and compressed. The entire operation sequence, including sludge feed control, polymer makeup, dosing and sludge cake discharge are controlled by the built-in timer and sensors of the PLC.

Advantages of dewatering press :-
• Simple process, low system investment, highly efficient and energy-saving dewatering.
• System can be programmed to make the operation more convenient and accurate.
• Unique flocculating agent to make sludge dewatering easier.
• Uniform and accurate dispensing saving running costs.

Dewatering Principle

It consists of layers of fixed and moving rings. There is slight variation in the inner diameters of the moving rings and the outer diameter of the screw and the fixed rings. Mobilized by the screw, it continuously cleans the sludge out of the gaps, therefore, preventing clogging.
Volute dewatering press 4

Structure Principle

The initial section of dewatering drum is the thickening zone, where the solid-liquid separating process takes place and where the filtrate will also be discharged. The pitch of the screw and the gaps between the ring decrease at the end of dewatering drum, hence increasing its internal pressure. At the end, the end plate further increases the pressure, so as to discharge dry sludge cake.


1. Wide Use

  • Can be widely used in treatment of municipal sewage, effluent related to food, slaughtering, breeding, printing and dyeing industry, oil & chemical industry, paper industry, leather, pharmaceutical and other industries.
  • Exclusive pre-concentration design.
  • Due to the innovation of the structure design, it is highly suitable to various high and low concentration sludge, most especially the oily ones.

3. Fully Automatic control

  • There are no parts that can get blocked such as belt and filtration fabric in multi disk screw press. Combining with the auto control system, the machine runs very safely and simply and can be programmed according to the requirement of the users. It can operate automatically for 24 hours, unmanned.

5. Contactless, Wear free structure design.

  • Multi disk screw press uses the contactless wear free structure between the disks and spiral shafts and thus the service life of the screw shafts and the rings are greatly extended. The treatment capacity of equipment and processing effects can be improved in combination with other design optimizations.
    • The contactless, wear free design in the sludge-water separation enhances the life of devices and shafts in the dewatering part.
    • Longer life; shafts over 10 years and rings over 5 years.
    • Wear free structural design to ensure a higher treatment capability and treatment effect

7. Decrease capital investment.

  • Multi disk screw press can treat sludge in aeration tank and secondary sedimentation tank without using sludge thickeners. Therefore, this decreases the total investment, avoids phosphorus release from the sludge thickeners and sludge storage tanks and enhances Phosphorus removal effect of the wastewater treatment system.

2. Clog-free

  • Due to rotation of the helical axis, the moving rings detach from the fixed rings while continuously starting the self-cleaning process. As a result, the ubiquitous clogging is avoided. Therefore, it can handle oily sludge without any trouble while separating the water from the sludge easily. In addition, there is no need to add large quantity of flushing water and there is no odor and no secondary pollution during the dewatering process.

 4. Save Running Cost

  • Multi disk screw press works by the machine`s internal pressure and needs no large scale integrations like rollers. It saves energy and water and has very minimal noise because of low running speed (2-4 r/min). The average unit power consumption is only 0.1-0.01 kwh/kg-DS (1/8th of belt press and 1/20th of centrifuge), and can greatly reduce the running cost of wastewater treatment system.

6. High resistance to oily sludge.

  • The self-cleaning mechanism and stainless steel structure enables multi disk screw press to be ideal to dewater oily sludge, which in other types of dewatering equipment easily causes clogging and is difficult to treat.

8. Small Footprints

  • Multi disk screw dewatering press can be installed in places where installation would not be possible with other technologies and methods. This makes multi disk screw press suitable to customers who are considering the replacement of existing dewatering equipment.

Comparisons indicated below. Dimensions for belt press and centrifuge are for the main bodies only. For other dewatering equipment, the dimensions of attachment, such as PLC Control Panels, flocculation tank, etc. are also included.






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