Office of Water
Technology Fact Sheet
Belt Filter Press
Belt filter presses are used to remove water from
liquid wastewater residuals and produce a
to as “cake”.
Dewatered residuals, or cake, vary in consistency
from that of custard to moist soil. Dewatering
serves the following purposes:
Reducing the volume, thus reducing storage
and transportation costs.
Eliminating free liquids before landfill
Reducing fuel requirements if residuals are
to be incinerated or dried.
Producing a material which will have
sufficient void space and volatile solids for
composting when blended with a bulking
Avoiding the potential of biosolids pooling
and runoff associated with liquid land
Optimizing subsequent processes such as
A belt filter dewaters by applying pressure to the
biosolids to squeeze out the water. Biosolids
sandwiched between two tensioned porous belts are
passed over and under rollers of various diameters.
Increased pressure is created as the belt passes over
rollers which decrease in diameter. Many designs
of belt filtration processes are available, but all
incorporate the following basic features: polymer
conditioning zone, gravity drainage zones, low
pressure squeezing zone, and high pressure
squeezing zones. Advanced designs provide a large
filtration area, additional rollers, and variable belt
speeds that can increase cake solids by five percent.
The general mechanical components of a belt filter
press include dewatering belts, rollers and bearings,
belt tracking and tensioning system, controls and
drives, and a belt washing system. Figure 1 depicts
a typical belt filter press.
Belt filter presses can be used to dewater most
biosolids generated at municipal wastewater
treatment plants and are a common type of
mechanical dewatering equipment.
mechanical equipment to dewater solids may