What is ultrafiltration

The use of ultrafiltration has become of increasing importance, especially in the field of drinking water treatment.

Inexpensive polyamides, polysulfanes and cellulose acetates are mainly used as membrane material. For more information, see also microfiltration.
In recent years, new developments have also made it possible to use the chemically very resistant ceramic membranes.

Ultrafiltration is often used to recycle the water in a production process, in which the water that has been contaminated by the production process has to be treated into service water.

Process description

With ultrafiltration, the medium to be filtered is pressed with pressure through ceramic or plastic tubes with an inner diameter of approx. 0.5 - 2 mm. The actual filter are the porous walls of these tubes, the filter pores of which have a diameter of approx. 0.01-0.05 μm. In this way, dirt with a size of 0.05 μm or more can be reliably retained and rinsed out again at regular intervals. Dissolved substances and salts can pass through the membranes of the filter tubes.

The great advantage of ultrafiltration compared to conventional filter methods is that the filtered water is absolutely sterile. The pores of the UF membranes represent a reliable barrier for bacteria and viruses.

By bundling many filter tubes in filter modules, the necessary area is created that enables a greater water flow. Depending on the application, these modules are of different sizes and thus enable different filter capacities.

Properties of ultrafiltration:

  • Complete barrier to microorganisms and particles
  • The ultrafiltration can be fully automated
  • By removing almost all of the substances that form the surface layer, subsequent membrane processes such as reverse osmosis can be operated with higher surface loads.
Ultrafiltration (UF) in size comparison with known water germs:

 

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