Nanofiltration
Nanofiltration is a pressure-driven membrane processes , the dissolved molecules, heavy metal - ion restrains and other small particles. By definition, membranes used in nanofiltration have a pore size of at most 2 nm , which distinguishes them from coarser membranes used in ultrafiltration and microfiltration . However, the next finer reverse osmosis process is required to completely separate all dissolved substances from the solvent . Compared to reverse osmosis, correspondingly coarser filters and lower working pressures are used in nanofiltration. However, the membranes used for filtration are mostly only temperature- or chemical-resistant to a limited extent, so that the application of the method is essentially limited to water treatment.
Applications
Nanofiltration is z. B. used for softening and removing heavy metals in the water treatment of production wastewater. In pilot projects (e.g. Heidelberg , Knittlingen ) it is currently being tried out in the settlement area, where it allows new constellations of water supply and sewage disposal.
In Voerde , operated by the subsidiary of Stadtwerke Dinslaken GmbH, Wasserwerke Dinslaken GmbH, a system is currently (2009) operating at partial load (blending with raw water to restore the drinking water quality). As soon as the city's extraction wells are contaminated by filtrate from the banks of the Rhine, they should be fully processed. The problem of Rhine water flow in the aquifer ( aquifer ) is the exposure to industrial chemicals and human pharmaceuticals that are entered by humans and are excreted, so there are traces leave of antiepileptic drugs and analgesics such as diclofenac evidence. Traces of the birth control pills and their hormonal components have also been found.
Individual evidence
- ↑ "Terminology for membranes and membrane processes" in Journal of Membrane Science , 120, 149-159, 1996.
- ↑ Archived copy ( memento of the original from July 16, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
Web links
- Experience and application potential of nanofiltration (PDF file; 283 kB)