Handex Insights

Is a Belt Press or Plate and Frame Filter Press the Right Choice for My Sludge Dewatering Needs?

Written by Jim Caccese | September 21, 2016

filter press

Sludge dewatering is the process of separating the solid and liquid components that make up sludge waste. This is done to make the sludge easier and more cost-effective to transport and dispose of.

Many industries and municipalities turn to sludge dewatering as a way to meet waste minimization and sustainability objectives. There are many different technologies that can be used to remove water from sludge, including belt and plate and frame filter presses.

What is a Belt Press?

The belt press is most useful when a continuous operation is desirable. Typically a belt press produces between 18% and 25% solids by weight in the cake.

Belt presses work by removing sludge onto two different dewatering belts where freestanding water molecules are separated from the sludge by gravity and are collected by a trough. Next, the thickened sludge is pressed between two belt filters and squeezed under rollers to force excess water from the sludge. Finally, the sludge is scraped off the belt and collected in a bin while the water content is transferred back into a wastewater system for processing.

Since the belt press performs a continual action, it is most effective on high-volume waste streams. It is commonly used for the following applications:

  • Paper mill sludge,
  • River silt, and
  • Municipal wastewater treatment plants.

What is a Plate and Frame Filter Press?

A plate and frame filter press uses pressure filtration to separate liquids from solids. Pressure is achieved through the use of a double diaphragm or in other cases, self-priming trash pumps.

There are two main types of filter presses that can be used:

  1. High-pressure plate and frame filter presses that typically produce filter cakes that are between 40% - 70% solids by weight.
  2. Low-pressure plate and frame filter presses that typically produce filter cakes that are between 25% - 50% solids by weight.

Plate and frame filter presses are useful when a high content of solid material are desirable in the filter cake. They operate by cycling so the batches they produce are referred to as “drops.”

Plate and frame filter presses are most often used in applications that deal with:

  • Biological sludge,
  • API separator sludge, and
  • Various sludge types where, for disposal, the cake needs to be as dry as possible and contain a high amount of solids.

About Handex

Handex is a provider of Pumping, Dredging, Sludge Dewatering and Treatment of industrial and process wastes and sediments. Our staff includes experienced Project Managers, Operators, Technicians, Fabricators, Mechanics and Health and Safety Professionals. Our objective is to meet and exceed client expectations while providing cost-effective services. In some cases, our clients find that the value of the raw materials returned to the process may pay for a portion of the sludge dewatering cost.


Author Avatar
Written by Jim Caccese
Jim Caccese is a senior client relationship manager for Handex. He is committed to providing the highest level of safe and quality service to our clients. Jim has extensive experience in the environmental industry including consulting, operations, construction, management, research/development and sales.

Topics: Dewatering