The process of reverse osmosis

The reverse osmosis is the reversal of the natural process of osmosis by applying an external pressure. The water to be cleaned and desalinated is led with high pressure along a semipermeable membrane. This membrane is only permeable for water. In this process the raw water will be separated continuously in a nearly salt-free permeate and a high concentrated solution. The concentrate contains the impurities of the raw water.

Physical pre-treatment of the water

To avoid fouling and scaling on the membranes of the reverse osmosis unit usually a pre-filtration to remove suspended particles and a pre-treatment to reduce hardness are necessary. A well known process to soften the water is the ion exchange. Downside is the need of salt (sodium-chloride), the logistic of supply and the disposal of the recycled water.

Example: A reverse osmosis unit with a size of 6.000 l/hour permeate causes costs of approx. 20.000 €/year for salt and wastewater. Not calculated are the costs for logistic and maintenance.

The physical water-treatment used by Technologie-Anwendungs-Zentrums instead of the ion-exchange does not need any salt to soften the water. Alternating current pulses of 1kHz transform calcium ions with a high chemical potential into bigger agglomerates steady against flow with a reduced chemical reactivity. These agglomerates will be removed of the reverse osmosis by flowing with pure water.

The use of the physical water-treatment shows major advantages:

  • no costs for salt
  • no costs for water needed for a sodium-chloride production and recycling
  • no costs for wastewater