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What is a Filter Press and How Does it Work?
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<p>
A <a href="http://www.cjfilterpress.com/filter-press/" target="_self">filter
press</a> is one of the oldest and most trusted pieces of dewatering equipment. It’s
used for wastewater treatment across a variety of industries and applications. A filter
press works by separating out solids from liquids, removing impurities, and suspended
solids from industrial wastewater. This allows plant managers to easily handle and dispose
of waste while returning clean water to their systems.
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<p>
Filter presses separate liquids and solids. Specifically, the filter press separates
the liquids and solids using pressure filtration across a filter media. Afterward, the
slurry is pumped into the filter press and then dewaters under pressure.
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<p>
Basically, the <a href="http://www.cjfilterpress.com/filter-press/concentrate-filter-
press/" target="_self">concentrate filter press</a> design is based on the dewatering
volume and type of slurry. ChemREADY is an expert in liquid and solid separation and offers
a wide range of filter press types and capacities to suit specific application needs for
trouble-free, economical dewatering.
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<p>
The origin of the filter press dates to around the mid-19th century in the United
Kingdom, where a rudimentary form of the press was used to obtain vegetable oil from seeds.
However, it wasn’t until major developments in the mid-20th century that engineers were
able to develop the world’s first automatic horizontal-type filter press.
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<p>
It’s this long history of advancements that’s allowed the filter presses of today to
achieve significantly lower energy and maintenance costs compared to their belt press and
centrifuge counterparts. In fact, the total operating filtration cost for a filter press
can easily be 1/6 the cost of what it would be for a belt press or centrifuge.
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<p>
While there are many different styles of modern filter presses, the plate and frame
filter press are one of the oldest and most tested types of dewatering equipment available.
You can read more on this type of filter press, along with a more detailed comparison
between different types of dewatering equipment, in our Water Facts blog on How Industrial
Wastewater Pretreatment Works.
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<p>
Filter presses are especially useful as the leftover solids are cheaper and easier to
move than the entire slurry. With the clean water that filter presses return, plant
managers can discharge that to their local municipalities, watersheds or use the water in
their own closed-loop systems, creating highly efficient processes.
</p>
<p>
Without a filter press or similar pieces of dewatering equipment, a settling pond is
often the first option for water treatment. Not only do ponds require a large amount of
real estate to use, but they also lose their ability to clean water over time as the solids
that you remove build up in the pond water. This gives ponds an unfavorable long-term ROI
as dirty water will eventually start coming back into your process unless you dredge the
pond or make a new pond. At ChemREADY, we advise the use of a filter press and other
dewatering equipment over a pond in most applications.
</p>
<p>
During the fill cycle, the slurry pumps into the filter press and distributes evenly
during the fill cycle. Solids build up on the filter cloth, forming the filter cake in the
void volume of the plate. The filtrate, or clean water, exits the filter plates through the
ports and discharges clean water out the side of the plates.
</p>
<p>
Filter presses are a pressure filtration method. As the filter press feed pump builds
pressure, the solids build within the chambers until they are completely full of solids.
This forms the cake. The filter cakes release when the plates are full, and the cycle is
complete. Also, many higher capacity filter presses use fast action automatic plate
shifters which speeding cycle time. Matec specifically designs their filter presses for
fully automatic, 24-hour operation in a harsh environment such as mines or chemical
manufacturing plants for wastewater treatment.
</p>
<p>
While the various styles of filter presses work differently, they all operate under
similar principles. Slurries of water mixed with solids are pumped into the press by using
a feeding pump. Once inside the press, pressure – often from a centrifugal pump or similar
device – pushes the slurry through chambers made of filter plates. This removes impurities
from the water as “filter cakes” of solids build up on the machine’s filters.
</p>
<p>
Once the chambers of a filter press are full, its filtration cycle is complete, and the
machine releases the filter cakes. These cakes are easily removed, allowing you to filter
your water at high efficiencies. In filter presses, fast action automatic plate shifters
may be used to help speed up cake removal and cycle time. In harsher environments where
continuous operation is required – like in mining processes or chemical manufacturing
plants – a fully automatic filter press design is needed to handle the 24-hour workloads.
</p>
<p>
To get the best performance out of your filter press, the cloth of the filter should be
specifically designed for your application and the types of solids that you are filtering.
</p>
<p>
The following can also be customized to fit your individual needs:
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<p>
In addition to these, you can use additional systems such as cloth washing systems,
drip trays, and cake shields to further increase filter press performance and
functionality. Ultimately, each filter press should be designed based on the expected
volume and type of slurry that it will be handling.
</p>
<p>
Since filter presses work using pressure, equipment that increase pressure through the
means of high-pressure technology are great for optimizing your <a
href="http://www.cjfilterpress.com/filter-press/dry-tailings-filter-press/"
target="_self">dry tailings filter press</a> system. That’s the secret to success for
Matec® filter presses, which use pressures of 21 to 30 bar to handle even the most
difficult and hard to treat slurries, no matter the sector or application.
</p>
<p>
Filter presses can be built in a wide range of sizes, from small, lab-scale presses, to
those with much larger capacities, such as those with 2000×2000 mm plates.
</p>
<p>
While filter presses are great pieces of dewatering equipment, they are best used on a
slurry made up of about 50-60 percent solids. Lower solids concentration requires running
the water through a clarifier first.
</p>
<p>
Clarifiers are best described as large settling tanks, preferably used in the initial
dewatering phase. Here, water can enter at a much lower solids concentration, typically
around 5-10 percent solids. Using gravity and polymers, clarifiers cause solids to build up
at the bottom of the tank, where they can be discharged as sludge.
</p>
<p>
The two main types of clarifiers are the horizontal rake style clarifier and
the vertical deep cone clarifier. Vertical deep cone clarifiers use the principle of
static decantation for a natural precipitation of solid material, while horizontal rake
style clarifiers use a rake mechanism that stirs the sludge through rotation. Determining
which type of clarifier is best for you depends on your clarifying needs, driven by
maintenance costs, material types and solids requirements. You can read more on the two
different types of clarifiers in our Water Facts blog, Deep Cone vs. Rake Style
Clarifiers.
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