METAWATER

Sludge treatment solutions in sewage sector

Rotary press filter

Outline

Rotary press filter

We successfully simplified the structure of our rotary press filter by adopting an innovative dehydrating mechanism. The sludge dehydrator has a drastically improved maintainability and management performance. It is a next-generation sludge dehydrator with many excellent advantages including energy-saving and space-saving characteristics.

Highly acclaimed next-generation sludge dehydrator

In this rotary press filter, a filtration chamber comprised of two metal disc filters and a resin spacer rotates at low speed. By pressing the flocculation sludge into the chamber with approx. 50 kPa pressure, the press-in pressure, screen rotation force and back pressure generated on outlet are combined to dehydrate the sludge. Despite its extremely simple structure, this sludge dehydrator demonstrates excellent dehydration performance.

Characteristics

Simple structure

Because no special process is needed for start-up and shut-down, and the number of components is smaller, operation, maintenance and management can be conducted more easily.

Wide range of treatment capability

Because the number of chambers in the channel can be increased easily, it can address a wide range of treatment capacities. The Ø11200 mm model has multiple types from a 1-channel to a 6-channel one, and chambers can be added in future.

Light and compact

The maximum screen diameter of the dehydrator main unit is Ø1200 mm. Therefore, it is lighter and more compact when compared to the conventional dehydrators.

Affordable component cost

Compared to the other models, this system requires less component and repair cost. Therefore, the initial running cost is inexpensive.

Sealed structure

Because of its fully sealed structure, there is no risk of an odor leakage. Odor prevention measures can be implemented easily.

Low power requirements

The rotation per minute of the main unit is as low as 0.5 - 1.3 rpm. The system emits no vibration or noise, and the power requirement is insignificant.

Modest water for washing

Because the metal filter does not cause clogging, there is no specific washing process during the operation. Also, because it is sufficient to carry out washing only in shutdown mode, the amount of water necessary for the washing is very small.

Dehydration mechanism

Dehydration mechanism

  • A filter chamber comprised of two metal disk filters rotates slowly at 0.5–1.3 rpm.
  • Initial filtration is performed in a filtration chamber, where sludge modified with a polymer coagulant is supplied by a sludge supply pump at a maximum pressure of 100 kPa.
  • With the progress of initial filtration, a solid cake layer develops gradually on the filter surface. Capture of this solid is further enhanced by filtration and dehydration through the filter cake, which makes the filtrates clearer.
  • During the process of moving from the filtration zone to the press-dehydration zone,the sludge will lose fluidity and be pressed towards the exit by the rotation of the disk filter.
  • Meanwhile, at the exit, the back pressure inside the filter chamber is maintained at a constant maximum of 600 kPa (variable) by a dynamic butterfly valve, supported by an air spring. This back pressure press-dehydrates the sludge.
  • The sludge at the filter surface with decreased water content in the press-dehydration zone is moved towards the exit in pace with the rotation speed. However, the sludge with relatively high water content in the center of the filter chamber undergoes further dehydration through the shear force generated by the difference in speed between the sludge at the filter surface and that in the chamber center.
  • After a series of drying processes, the cake is exhausted from the thickener by pressing it through the dynamic valve.
  • The screen does not need to be cleaned during operation. Cleaning it for approx. 5 to 10 minutes after operation is sufficient.

Application examples

This product can be applied to sewage-mixed raw sludge, sludge consisting of OD excess sludge, sewage-digested sludge, purification tank sludge and so forth.

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