Ultrafiltration is a water treatment technique that uses membranes to remove substances, bacteria and viruses.

How does ultrafiltration work?

In the case of ultrafiltration, an aqueous solution is put under pressure, which pushes the solution through a membrane. The treated water runs through the membrane whilst a large part of the solution’s substances is stopped by the membrane.

Different types of membrane can be used for ultrafiltration. The choice of a membrane is determined by a number of criteria, amongst others the required capacity and quality of the water that needs to be filtered.

The ultrafiltration’s principle does not fundamentally differ from other technologies such as reverse osmosis. The main difference is the size of the particles stopped by the membrane.

Application: Savings due to a combination of ultrafiltration and reverse osmosis

Reverse osmosis can be used to produce demin water. A semipermeable membrane stops a large amount of the substances. When the feed water of the reverse osmosis is however too polluted, the membrane quickly gets blocked. In most cases, tap water is used as feed water. Its quality tends to be sufficient to avoid a quick blocking of the reverse osmosis.

However, tap water is expensive. This does not cause a problem for smaller reverse osmosis installations, but the cost can increase quickly for larger installations. This explains why from time to time rain, river or well water is used for larger reverse osmosis installations. In this case, ultrafiltration is recommended to protect the membranes of the reverse osmosis. The payback time of the ultrafiltration installation tends to be short (between 1 and 2 years).

An ultrafiltration can also be used in combination with reverse osmosis for waste water recovery and for the closing of the hydrologic cycle in order to minimize any waste.

Other applications

• Food and drinks industry
• Surface treatment (for example when extending the redress life of degreasing baths) 
• Chemical industry
• Pharmaceutical industry
• Dialyses
• ...