Polymer membranes, also called organic membranes, are filtration modules used within pressure-driven liquid filtration to remove targeted particles to purify, concentrate, and separate liquids.

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What are polymer membranes?

Polymer membranes represent a filter solution used for liquid filtration processes of various kinds of water and wastewater.

Polymer membranes are also often referred to as organic membranes. They are a family of membranes produced of polymers. The alternative to polymer membranes is ceramic membranes, also referred to as inorganic membranes. A polymer membrane is a semi-permeable filter media produced of polymers used for pressure-driven water treatment. The polymeric materials can, among others, be polysulfone, polyethersulfone, polycarbonate, polyvinylidene fluoride, polyamide, or cellulose acetate.

Polymer membrane technology is employed in large-scale industrial applications to treat water and wastewater in order to separate micron-sized particles. The membranes have a semi-permeable surface. This means that some particles can pass through the membrane while others are rejected. It is the membrane's pore size that defines the size of the rejected particles. The membrane pore size is defined in microns. One micron is one-millionth of a meter. Thus, membranes can separate even the smallest particles such as bacteria, viruses, protozoa, and salts.

Organic membranes can operate within microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. Microfiltration separates suspended solids, while reverse osmosis separates salts.

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Ultrafiltration Membrane Process
Example of one membrane filtration principle.

How do membranes work?

Membrane filtration is a simple pressure-driven technique to purify, concentrate, and separate liquids.

Membrane technology is highly alike regardless of the materials utilized for the membranes. Thus, polymer membrane technology is generally the same technology as that of its ceramic counterpart. A pressure generated by a feed pump will force the liquid purification process by forcing the liquid to pass through the porous semi-permeable membrane barrier.

A feed stream enters the membrane, and pressure is applied. This will separate the feed stream into two new streams, which are the permeate and the retentate. The permeate consists of the filtered liquid, which can pass through the porous membrane barrier. The retentate consists of the particles that are retained by the membrane barrier.

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What can polymer membranes be used for?

Organic membranes are employed in large-scale industrial applications for water and wastewater treatment.

Polymer membranes can operate within all four filtration technologies. They are used for microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. They can be used for water and wastewater treatment. They are, among others, used within dairy, bakeries, wine distilleries, alcohol distilleries, and cosmetics.

Polymer membrane preparation

Polymer membrane preparation can be performed using various technologies. Regardless of the preparation process, the main advantage of polymer membranes is the low preparation cost.

The material and the preparation process highly affect the membrane's chemical, thermal, and mechanical strength.

Sintering is a well-known membrane preparation method. It is both used for polymer and ceramic membranes. For this technique, membranes are prepared by sintering powders of organic materials for polymer membranes and inorganic materials for ceramic membranes. While polymer membranes are produced of organic materials such as polysulfone, cellulose acetate, polycarbonate, or polyimide, ceramic membranes are made of inorganic materials such as alumina, titania, zirconia, or silicon carbide. The advantage of organic membranes is that they can be sintered at lower temperatures than inorganic membranes, lowering the production costs.

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Advantages and disadvantages of polymer membranes and ceramic membranes

There are both advantages and disadvantages of polymer membranes. The alternative to polymer membranes is ceramic membranes. Ceramic membranes are a more expensive alternative. Yet, there are significant differences between the membrane properties.

Organic membranes are used in many industries. The main advantage of organic membranes is the low capital expenditure due to low manufacturing costs and easy scalability. Therefore, these membranes have been used for many industrial water treatment applications. Polymer membrane technology is especially suitable for water desalination processes through reverse osmosis. The polymeric material cellulose acetate is often employed for water treatment due to its high chlorine tolerance.

However, due to the polymeric membrane properties, the balance flips towards ceramic membranes within several industries and water treatment applications.   

Polymer membranes suffer from a low degree of mechanical, thermal, and chemical stability. Contrary, ceramic membranes possess a high degree of these exact attributes. This makes polymer membrane technology an inadequate technology for harsh industries, ultimately calling for ceramic membranes with stronger properties.

Ceramic membranes have the advantage of being able to withstand harsh chemical cleaning, high temperatures, and aggressive fluids with acids or strong solvents. Thus, ceramic membranes can be used in harsh environments, such as corrosive and high-temperature environments, where polymer membranes are inadequate. These industries can be:

  • Power plants
  • Oil and gas
  • Marine
  • Mining

With the current focus on sustainability and the rapid implementation of environmental regulations and discharge limits for various industries to obtain cleaner industrial processes, it becomes more and more essential to have durable and cost-effective filtration solutions that can withstand arduous industries.

Moreover, ceramic membranes can withstand harsh chemical cleaning for sterilization and frequent backwash, which is crucial for several industries in order to maintain superior hygiene standards. Any compromises on cleaning and sterilization can contaminate the operation and result in operational downtime. Industries with extensive hygiene needs can be:

  • Pharmaceutical
  • Cosmetics
  • Biotech
  • Food and beverage
  • Dairy

As ceramic membranes are more expensive to produce, they are linked with higher capital expenditure. Yet, this is compensated by an efficient membrane with a long lifetime, ensuring a low cost of ownership. The durable and hard inorganic material delivers a robust and stable membrane, which provides efficient and reliable operation and can withstand strong pressure and the stress it causes. As organic membranes are not as durable, they have a shorter lifetime and generally require more frequent replacement.

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Unique Properties

Features & Benefits

Perfect for harsh applications

  • Highest flux for any membrane material
    The high flux is reached through high membrane porosity (~45%) and a material with a low resistance to transport of water and a low contact angle. Reduce your footprint and system costs (fewer pipes, valves, etc.)
  • Chemically inert pH 0-14
    No limitations, fast cleaning, reduced downtime during Cleaning in Place (CIP), filtration of acids and alkalis.
  • Thermally resistant up to 800°C
    Steam cleaning, more efficient chemical cleaning, and high-temperature applications.
  • Hydrophilic material (water-loving)
    Unmatched performance in oil/water separation.
  • Isoelectric point pH 2.4
    Unmatched performance in oil/water separation – To some extent reduces fouling, easier to clean.
  • Extremely hard & durable material 2930 +/- 80 kgf/mm³ (Vickers scale)
    Robust and long lifetime, less downtime and maintenance, stable operation, cleaning with shock pulses, and hard material.
  • Abrasive Feeds
    Our silicon filter membranes are extremely durable, so abrasive feeds won’t damage the membrane.
  • Low power usage and low pressure
    Our membrane systems typically use around 7 psi or 0.5 bar of pressure (depending on the feed water), so you save money on pumps and energy
  • Long membrane life
    The silicon filter membrane is extremely durable (second hardest material in the world).
  • Low operational cost, low total cost of ownership
    With very infrequent membrane replacement, low power usage, and moderate chemical usage, the operational costs of membrane systems are low, and the total cost of ownership and low maintenance profile is very favorable compared to other systems.

Applications Areas

Silicon carbide ceramic filters are ideal for the treatment of:

  • Wastewater
  • Produced water
  • Pre-RO filtration
  • Polymer flooded streams
  • Control of soot exhaust particles
  • ... and many more

Comparison of different membrane materials

Silicon carbide is the best material for filtration applications

Membrane Material
Type SiC Other ceramic Polymer
Cost of ownership +++ ++ +
Lifetime +++ ++ +
Flux +++ ++ +
Chemical resistance +++ ++ +
Energy savings +++ ++ +
Recovery rate +++ ++ +
Fouling tendency +++ ++ +
Relaxation time None None Yes
Temperature resistance +++ ++ +
Hardness +++ ++ +
Porosity +++ ++ +

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