Rotary press filter

Outline

The rotary press filter is a sludge dehydrator of which we have successfully simplified the structure through the adoption of an innovative dehydrating mechanism and drastically improved maintainability. It is a next-generation sludge dehydrator with many excellent features, achieving energy-saving and space-saving effects.

The next-generation sludge dehydrator that the market has hoped for

In this rotary press filter, a filtration chamber, comprised of two (2) metal disc filters and a resin spacer, rotates at low speed. By pressing coagulated sludge into the chamber with a pressure of approximately 50 kPa, the sludge is dehydrated as a result of the combined effects of the press-in pressure, the screen rotational force and the back pressure generated at the outlet. Despite its extremely simple construction, this sludge dehydrator demonstrates excellent performance when it comes to dehydration.

Features

Simple construction

It is easy to operate and maintain since it requires no special processes for start-up and shut-down and has only a small number of components.

Wide range of treatment capabilities

The number of chambers in the channel can be increased easily, so it can meet a wide range of treatment requirements. The Ø1200 mm model has multiple types, ranging from 1-channel to 6-channel. The addition of chambers can take place in the future.

Light-weight and compact

The maximum screen diameter of the dehydrator main unit is Ø1200 mm. It is lighter in weight and more compact than conventional dehydrators.

Affordable equipment costs

When compared with other models, the initial and running costs are lower. Less costs are required for the equipment and for repair.

Sealed construction

Its fully sealed construction means that there is no risk of odor leakage, making it easy to implement odor prevention measures.

Low power

With the speed of the main unit being as low as 0.5-1.3 rpm, the system emits no vibration or noise and its power requirement is very small.

Modest amount of water for washing

The metal filter does not cause clogging, so it requires no particular washing process during operation. Washing is required only when the system is stopped, so the amount of water used for washing is very small.

Dehydration mechanism

• A filter chamber, comprised of two (2) metal disk filters, rotates at a slow speed of 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. Solids are captured even more by means of filtration and dehydration through the filter cake, making 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 discharge port by the rotation of the disk filter.
• Meanwhile, at the discharge port, the back pressure inside the filter chamber is maintained at a constant level of a maximum of 600 kPa (variable) by means of a dynamic butterfly valve supported by an air spring. This back pressure press-dehydrates the sludge.
• And, in the press-dehydration zone, the sludge on the filter surface with decreased water content is moved toward the discharge port at a pace commensurate with the rotational speed. However, the sludge with relatively high water content at the center of the filter chamber causes a slip against the sludge on the filter surface, generating a shearing force as a result of the difference in speed. The shearing force accelerates the dehydration.
• After a series of drying steps, the cake is discharged out of the thickener by having it pressed through the dynamic valve.
• No washing is required during operation. Washing for approximately 5 to 10 minutes after operation is sufficient.

Application example

This system is applicable for sewage-mixed raw sludge, sludge consisting of OD excess sludge, sewage-digested sludge, purification tank sludge and so forth.