There are three basic types of filter plates used in conjunction with filter presses. They include recessed chamber, plate and frame and membrane squeeze plates.
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Membrane squeeze, or diaphragm squeeze, filter plates offer a number of benefits, from time savings to improving the lifespan of the membrane. M.W. Watermark™ offers membrane squeeze filter press/plate solutions to a range of industries. Discover how membrane (diaphragm) squeeze plates work and what advantages they bring to the table.
Membrane squeeze presses operate similarly to recessed chamber and plate and frame filter presses that utilize polypropylene filter plates. However, the chambers in the filter plates have membranes to squeeze out the excess water from the slurry. As a result, this type of filter press may be able to remove a significant amount of fluid. And therefore, they can also reduce cycle time as long as the filter cake is compressible.
Membrane squeeze presses and plates are also considered when the slurry has higher than average solids and/or has variable volume, and when the time saved by the squeezing process can be justified by higher equipment costs. (Time is money).
In a typical filter press application, approximately 80% of the solids are pumped into the press in the first half of the cycle, with the remaining half considered the consolidation stage. With membrane squeeze, the cycle is shortened and the cake moisture content is reduced (see chart).
The result is increased throughput and better liquid recovery. Adding membrane squeeze to a filter press requires a specialized plate stack, a squeeze water manifold, and a filter plate pressurization system. Typically, membrane plates are alternated with standard chamber plates in a “mixed pack” as shown in the photo below.
The filtration process of a membrane squeeze filter press typically includes six steps. Here’s how membrane squeeze filtration works:
Now that we’ve discussed how membrane squeeze filter presses work, let’s summarize the benefits of adding a membrane filter press to your operation.
Because diaphragm filter presses utilize membrane technology, they greatly influence the dryness of the filter cake. When put head-to-head against standard filtration processes, membrane filtering achieves the lowest residual moisture values in the solid. This is vital in filtering applications where the degree of dewatering is of the utmost importance, especially in applications where the separated solid or liquid is the actual product.
In addition to achieving a high degree of dewatering, membrane squeeze filter presses and plates also help reduce the filtration cycle time. With a faster cycle time comes faster turnaround times, which consequently can lead to an increase in productivity.
Another advantage of using membrane plates can be found in the option for replaceable vs. welded diaphragms. If the membrane component happens to break, the diaphragm itself can be removed and replaced, versus requiring the replacement of the entire filter plate. This provides for a significant cost savings and a quicker fix over waiting several weeks for replacement welded membrane plates to arrive.
Also, if chemical compatibility is a concern, replaceable diaphragms are offered in various materials of construction, including EPDM, NBR, Viton, and more.
From chemical plants to gold mining and everything in between, membrane filter presses and plates have been used successfully in a number of applications. Find out if utilizing a membrane/diaphragm squeeze filter press is right for your particular application by reaching out to M.W. Watermark. Contact us to learn more or request a quote today.
M.W. WATERMARK wants to make a difference. We are passionate about the world’s water. We are innovative, focused on customer service and always try to exceed expectations. We are an environmentally conscious company with people who are energized, encouraged and inspired to make a difference on our planet by helping to keep our shared, finite water supply clean and usable for generations to come. We build amazing, custom water and wastewater treatment equipment. Together, we can make a difference.
Air operated diaphragm pumps are used with filter presses to pump sludge from the bottom of the sludge holding tank into the filter press. These pumps are ideal because they can handle the slurry which is generally about the consistency of a milkshake.
The diaphragm pump usually starts out slowly and gradually ramps up. Once the pump starts to slow back down, (30-60 seconds between thrusts), it is usually an indicator that the filter press is full. At this point, the feed pump should be turned off and the valves on the filter press closed as the operator prepares to operate the air-blow-down process.
The diaphragm pump can be manually turned up or an Automatic Pump Control system may be added. This starts the pump at 25 psi, then moves up to 50, 75 and finally 100 psi which is standard operating pressure for the pump.
Met-Chem provides diaphragm pumps in the following sizes: 1”, 1.5”, 2” and 3”. The material of construction ranges from cast iron, aluminum, polypro or stainless steel.
With the purchase of a new Met-Chem filter press, Met-Chem can mount your air operated diaphragm pump to the legs of your filter press. This option also includes a flex hose that connects the outlet of the diaphragm pump to the center feed pipe, an air filter, a regulator, and an oiler. We can also provide a mounted diaphragm pump for your existing press.
Automatic Filter Press Pump Control SystemThe Met-Chem Automatic Pump Control System is used in conjunction with an air operated diaphragm pump to automatically increase the feed pump pressure at predetermined intervals during the filter press filling cycle. If the pump runs at a higher initial pressure, the filter cake will become a packed layer of solids on the filter cloth. This will restrict the flow of the slurry thereby creating a very dense coating of the filter cake. This can cause the cloths to blind off and not allow further filtration. Starting at a lower feed pressure allows a soft layer of slurry particles to be deposited on the filter cloth. This initial layer becomes the filtering media which will enhance the filterability of the incoming slurry.
Want more information on filter press for sludge dewatering? Feel free to contact us.
The automatic pump control system automatically and gradually increases the feed pressure in four stages during the filling cycle. These stages are adjustable to suit your slurry and solids concentration. However, it is commonly set at increments of 25 psi. (25, 50, 75, 100). By monitoring the feed pump flow sensor, during the final pressure stage, the operator will be able to determine the cycle completion.
The Automatic Pump Control System also incorporates a low hydraulic pressure safety shut down the device. If there is not enough hydraulic clamping pressure present, the system will completely shut down, eliminating any possible leaking from between the filter plates.
The pump control system allows your filter press to run at its optimum efficiency creating dryer filter cakes, reducing disposal costs, reducing operator time and increasing the life of your filter cloths and feed pumps.
This system can be incorporated with a new filter press from Met-Chem, a used unit or even your own existing press.
Spare Parts KitMet-Chem is pleased to offer our spare parts kit which includes our 5 piece center feed pipe assembly, a head, tail, and 2 intermediate filter press cloths, and 100 foot of gasketing material. These are essential items for the operation of the filter press. A cracked pipe, ripped cloth, or torn gasket can happen anytime and having these items in your stock will ensure you will be back up and running in no time.
Center Feed and Manifold Filter Press UpgradesA center feed pipe assembly on a filter press should be able to last many years the same way any other type of plumbing will. However, if the material of the center feed pipe assembly is not strong enough to handle the corrosiveness of the solution running through the press then the center feed pipe assembly can corrode.
For cases of corrosive material or high temperatures, Met-Chem is pleased to offer upgrades from our standard center feed pipe and manifold. We are able to upgrade to CPVC, Carbon Steel, 304 or 316SS Stainless Steel, and Titanium. Met-Chem can also provide additional manifold upgrades such as automatic valves
The center feed pipe is what connects the filter press to the product that needs to be filtered. The center feed pipe assembly consists of five different parts. The first part is the lock nut which fastens on the center feed pipe and connects to the outside of the press. The pipe, which is the second part, goes through the head of the filter and all the way through the head plate of the filter press. The third part of the center feed pipe assembly is a gasket which ensures the assembly is watertight. Next, is the clip nut seat which fastens the assembly to the head plate. This part of the assembly will always stay in place unless you are replacing the assembly or one of its parts. The final part, the cloth clip nut, will be removed often as it is screwed into the cloth clip nut seat after the head cloth is put on the head plate. The cloth clip nut needs to be tightened in order to keep the cloth in place. Met-Chem provides a tool to make this process easier. The Met-Chem Spanner Wrench is a specially designed tool that can be used to loosen and tighten the cloth clip nut when changing the head cloth on a filter press. This tool can be very helpful as the cloth clip, but it has a design that requires a unique tool to tighten and loosen it.
Longer Legs and Filter Press Sludge Disposal ChuteMet-Chem can provide longer legs and a disposal chute on your new filter press. This is especially useful if you are releasing the sludge from the press into a sludge bag or a drum. The chute will direct the sludge directly into your container. If you plan to use a sludge disposal bag, we can add hooks to the chute so that the sludge bag can be hung from the frame of the press.
For some larger presses, we can build a catwalk along with the disposal chute in order to accommodate a roll-off container.
Sludge DumpsterSludge Dumpsters are used directly under the filter press to catch the sludge that is released from the filter press during cleaning. The dumpster is on casters for easy mobility. They are also equipped with forklift slats for convenient use with a tow motor. The operator can move the dumpster to a roll-off container with the forklift and then pull the release pin for easy emptying. The dumpster can then be snapped back to the upright position and put back under the filter press.
Backer Plate for Smaller Filter Press BatchesIf you produce varying size batches of wastewater and subsequently less sludge, or if the overall volume of waste that is generated at your facility has been reduced, you can still utilize your existing filter press. With the purchase of a backer plate, you can alter the holding capacity of your press to meet your individual batch needs.
A backer plate provides support to the tail plate so that it can be moved anywhere in the plate pack in order to isolate the chambers between the feed end and the tail plate. If you try to use the tail plate in a different position in the plate pack without the backer plate, you run the risk of damaging the chamber of the tail plate.
There are different kinds of backing plates. Some are made of plastic and look much like a standard plate; we prefer to use ~3/8” thick flat stock steel and cut an outline of a plate. This is clearly visible when placed in the stack so that all around know that the filter press is not at full capacity. This steel backing plate is then painted with the same two-part epoxy coating as the frame of the filter press.
Filter Press Plate ShiftersOur standard filter presses can be operated manually. However, Met-Chem manufactures four types of filter press plate shifters to make operating your filter press easier, safer and more efficient. Manual filter presses require more time and attention than the same filter press with an automatic plate shifter.
For some larger presses, we can build a catwalk along with the disposal chute in order to accommodate a roll-off container.
Start-Up Assistance / InstallationThe start-up and installation options are available with all Met-Chem waste treatment equipment. We can provide full support as you get your system up and running. We have installation technicians and technical representatives that we can send to your facility to make sure the system is running as it should based on the engineering and design.
Our services include but are not limited to:
All units and systems are complete with manuals and support. However, if you need someone to come to your facility, we will be happy to quote you on that as well.
Learn more about our Start-Up Assistance and Installation