Nanofiltration

Nanofiltration is a pressure-driven membrane processes that retain solute molecules, heavy metal ions, and other small particles. Membranes which have to be used in nanofiltration, by definition has a pore size of at most 2 nm, which makes it different from coarse membranes used in the ultrafiltration and microfiltration. For complete separation of all solutes from the solvent, however, the next finer process of reverse osmosis is required. Compared to the reverse osmosis filter will be correspondingly coarser and lower working pressures are used in nanofiltration. However, the membranes used in the filtration are usually only a limited temperature and chemical resistance, so that the application of the method is substantially limited to water treatment.

Applications

Nanofiltration is eg used for softening and removal of heavy metals in water treatment of waste water production. In pilot projects (eg Heidelberg, Knittlingen ), it is currently being tried in the municipal area where it allows new combinations of water supply and sanitation.

In Voerde, operated by the subsidiary of Stadtwerke GmbH Dinslaken, the waterworks Dinslaken GmbH, a plant ( 2009) ( blending with raw water to drinking water quality set again) is currently working in the partial load operation. Once the wells of the city are contaminated by Rheinuferfiltrat, to be made a full treatment. The problem of Rhine water flow in the aquifer ( aquifer ) is the exposure to industrial chemicals and human pharmaceuticals, which are entered and excreted by humans, so can be traces of antiepileptic drugs and analgesics such as diclofenac prove. Furthermore, traces the birth control pill with their hormonal constituents have been detected.