Filtration technology serves as a fundamental process in industries ranging from medicine and food to everyday life, facilitating the cleaning and separation of liquids and gases.

Among the prevalent methods, microfiltration and ordinary filtration exhibit discernible disparities in filtration precision, application range, and material preferences.

Sanitek will conduct a comparative analysis between microfiltration and general filtration to elucidate their distinct characteristics and optimal application scenarios.

Our aim is to provide readers with a comprehensive understanding of the disparities between these two filtration methods.

What is Filtration?

The filtration process involves the retention of contaminants within a fluid. It entails passing fluids through porous, permeable media to trap contaminants present in those fluids.

While seemingly straightforward, filtration requires careful execution. It’s crucial to note that conventional filtration methods may not capture contaminants as small as microns.

In general, ordinary filters retain contaminants between 20 and 25 microns. It is one of the most effective alternatives for extending the life of fluids, eliminating 99% of water, 62% of sludge, and 86% of particles under 10 microns.

The filterability of a material depends on three properties:

• Fluid pressure over the area of the filter material

The fluid flow rate through a filter increases with higher pressure applied over the filter material’s surface area. However, excessively high pressure can lead to filter damage or premature failure.

Hence, careful consideration of fluid pressure is crucial during filter design to guarantee long-term stability and efficiency.

• Resistance of filter material to fluid passage

Different filter materials have different pore structures and surface properties, and these properties affect the resistance to fluid passage.

Typically, the smaller the pores of the filter material, the greater the resistance, because the fluid needs to overcome a greater resistance to pass through. Therefore, the selection of the proper filter material is critical to ensuring the performance of the filter.

• Resistance of generated residue (filter cake)

Throughout the filtration process, solid particles or substances are trapped by the filter, forming a residue known as filter cake. As the cake thickens over time, fluid resistance increases.

Thus, timely removal or replacement of the filter cake is crucial to sustaining proper filter function. Additionally, filters must be designed with cake formation and management considerations to ensure continuous and efficient operation.

How does filtration work?

Filtration is a process in which fluid in suspension (or dusty gas) located on one side moves through the pores of a porous medium to the other side under the action of a propulsive force.

The particles are retained, thus completing the process of operating the fluid and particles separately. The filtered suspension is also known as the slurry, the layer of particles intercepted during filtration is called the cake, and the clear liquid from filtration is called the filtrate.

Filtration cleans water by pushing it through a membrane with small holes, called pores. The pore size is measured in microns, abbreviated um. (One micron is one-millionth of a meter.) As the water passes through the pores, substances in the water stick to the membrane.

What is microfiltration?

Microfiltration, commonly abbreviated as MF, Operates within a pressure range of 0.07 to 0.2 MPa, microfiltration effectively retains particles, bacteria, pollutants, and more from both gas and liquid phases. It serves as an indispensable method to uphold product quality standards in modern industries.

Microporous filtration, targeting particles ranging from 0.02 to 10μm, is employed for separation purposes. In microfiltration, particles within fluids, oils, and emulsions are separated utilizing filter elements with pore sizes ranging from 0.1 to 10μm. Consequently, substances larger than the pores are effectively retained within the fluid.

Unlike filtration, microfiltration is capable of capturing smaller micron contaminants, even microscopic 2 microns. This ensures more effective retention, as these small particles are the cause of the biggest problems in equipment.

How does microfiltration work?

Microfiltration operates through a microporous membrane as its filtration medium, primarily retaining colloidal and suspended particles via sieving.

Two common types of microfiltration membranes are curved pore and straight pore membranes, each employing different retention methods such as mechanical retention, bridging retention, and network internal retention due to variances in membrane structure. Factors like adsorption and electrical properties also influence retention.

The operation of microporous cartridge filtration relies on the pressure exerted on the filtered suspension, which propels it through the membrane.

During this process, the liquid and small solutes permeate through the membrane, while suspended particles are retained and collected as a concentrate.

The retention mechanism is determined by various factors, including the membrane’s physical and chemical properties, as well as the nature of the interaction between the membrane and particles.

When the membrane’s pore size is smaller than that of suspended particles, the particles are blocked geometrically, unable to penetrate the membrane, resulting in surface filtration or sieve filtration.

Conversely, if the membrane’s pore size exceeds that of the particles, they can enter the pores. Upon contact with the pore wall, they adhere and are filtered from the suspension. This mechanism, occurring within the depth of the membrane, is known as depth filtration.

Characteristics of microporous filtration

• Easy, efficient and economical filtration equipment.
• Wide range of filtration precision, ranging from 1 to 1000 microns.
• Diversified filter materials, including nylon, polypropylene, polyester, polyarylamide, polytetrachloroethylene and so on.

Microporous filter usage guidelines:

Prior to usage, select appropriate filter cartridges based on filtration objectives, media conditions, and other relevant factors.

For instance: In pharmaceutical water filtration, employ 5μm and 1.0μm pleated membrane cartridge filters arranged in tandem.

In the fermentation industry, utilize microporous filters for air filtration tasks, such as decontaminating incoming air, removing phages, and sealing exhaust gas treatment to comply with the U.S. bacterial filtration HIM standard.

Microfiltration vs.Normal Filtration

Having understood the concepts of general filtration and Microfiltration filtration, Sanitek takes you through a summary of the differences between the two.

Understanding the types of microporous membrane filter cartridge

Microporous membrane filter is usually a combination of microporous membrane folded cartridge and filter housing.

The microporous membrane is processed by Sanitek’s professional pleating process, together with the support layer made of PP material and the outer skeleton, etc.

Subsequently, by using the heat fusion welding technology for the welding of the cartridge, the high-efficiency filtration requirement is achieved.

The pore size of the microporous filter membrane is very uniform, porosity of about 80%, and a number of holes up to 107 ~ 101 / cm2.

Early microfiltration membrane materials are nitrocellulose, mainly mixed cellulose ester, regenerated cellulose, polyvinyl chloride (PVC), polyamide, polytetrafluoroethylene (PTFE), polypropylene (PP) and polycarbonate (PC).

Where can I go to buy microfilters?

When it comes to choosing the right microporous membrane filter cartridge for your needs, you can count on Sanitek, which is committed to providing a wide range of cartridges made from quality materials to meet the needs of a variety of industries and applications.

Sanitek ensures your peace of mind by providing dependable, high-quality products. With us, you can enhance your fluid handling and filtration processes, achieving greater efficiency and reliability.

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