Introduction of ultrafiltration technology


Definition of Ultrafiltration technology

Ultrafiltration is a kind of membrane filtration and separation technology driven by hydrostatic pressure, the separation process using asymmetric porous membrane with pore sizes in the range of 0.1 to 0.001 micron as filtering medium for water treatment, the process is designed to intercept all kinds of macromolecular solutes, suspended solids, bacteria, colloidal matter in the solution to achieve the purpose of separation, purification and concentration.

Application range

Due to the high effectiveness of removing effectively remove particles, colloids, bacteria, heat sources and organic matter in water, ultrafiltration technology has been widely used in the separation, purification and concentration of liquid materials in high-tech bioengineering, pharmaceutical process, fine chemical industry and other industries.

In the past 30 years, ultrafiltration technology developed very rapidly, It not only plays a unique role in the separation of special materials or solutions but also has increasing application demand in industrial water supply. For example, in the preparation of seawater desalination, reclaimed water, pure water and high purity water, ultrafiltration can be used as pretreatment equipment to ensure the long-term safe and stable operation of follow-up equipment such as reverse osmosis.

Difference between microfiltration (MF) and ultrafiltration (UF)

According to the spectrum of separation range and pore size from reverse osmosis to microfiltration, you can obviously figure out that the main difference is the pore size, ultrafiltration pore sizes fall between that of nanofiltration and microfiltration, basically, they all do the same job but the different pore sizes allow for different elements allowed to be passed through. This helps you to find out the suitable solution for your water treatment.

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Ultrafiltration membrane materials

The materials used to make ultrafiltration membrane can be divided into organic material and inorganic material. Organic materials include PVDF, PES, PP,PE, PVC and other polymers, inorganic materials include aluminum oxide (alumina), zirconia, silicon carbide and stainless steel, among which silicon carbide material with more stable characteristics of robust chemical, temperature resistance and low fouling tendencies, and with more extensive application environment.

When ultrafiltration is used in water treatment, whether it is organic or inorganic ultrafiltration membrane, its material stability and hydrophilicity are the two most important properties. Stability includes two aspects, firstly its chemical stability determines the life of membrane materials under the action of acids and bases, oxidants and microorganisms, and it is also directly related to the choice of the cleaning process; secondly, its physical stability determines the requirements of membrane materials for influent pretreatment, whether it can withstand the impact of high suspended solids, physical wear and physical damage. Hydrophilicity determines the anti-fouling ability of membrane materials to foulants in water, operating pressure, and affects the flux of the membrane.

Ultrafiltration separation characteristics

1.The separation process does not change in phase and less energy consumption

2.The separation process can be carried out at room temperature, which is suitable for the concentration or purification of some heat-sensitive substances.

3.Driven by low pressure, the equipment and process are easy to operate, manage and maintain.

4.Wide range of applications for different sizes and molecular weight of solute.

Ultrafiltration operational mode

1.Dead-end filtration

The feed water is placed upstream of the membrane, driven by the pressure difference, the water and particles smaller than the pore of the membrane pass through the membrane, and the particles larger than the pore are intercepted by the membrane. However, the retained particles accumulated on the membrane surface and consequently, the filtration resistance increased, this may result in a decrease in flux.

The dead-end filtering operation is simple and suitable for small-scale occasions. Materials with solid content less than 0.1% are usually filtered by the dead-end mode.

2. Cross-flow filtration

Cross-flow filtration, also known as tangential flow filtration, where the feed flow passes tangentially to the membrane surface, while one portion passed through the membrane (permeate) as purified water, the other part carries suspended matter larger than membrane pore (retentate) remains and recirculated back to maintain the shear force produced by the higher flow velocity, so as to keep the fouling layer at a thin level.

Cross-flow filtration has the advantages of low energy consumption, low operating pressure and cost-effective, while it can deal with feed water with higher suspended matter content.

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Jmfiltec believes that inorganic ultrafiltration membrane will gradually replace the application advantage of organic membrane, and silicon carbide inorganic ultrafiltration membrane will become a new highlight in the application of membrane filtration technology. Currently, we can offer you 4 series of silicon carbide ultrafiltration membranes, conventional SiC tubular membranes and flat sheet membranes. revolutionary sliced sectors column type membrane and MCR tubular membrane.

We warmly welcome your contact for further consultant and discussion with us.


Author: Aaron Lu