Membrane technology in general

Membranes can be subdivided according to their filtration properties in 4 categories:

  1. Micro-filtration (MF), range 0,1 - 1 micron (1 micron = 1/1000 mm);
  2. Ultra-filtration (UF), range 0,001 - 0,1 micron;
  3. Nano-filtration (NF), range 0,0001 - 0,001 micron (0,001 micron = 1 nanometer - nm);
  4. Reverse osmosis(RO), bereik < 0,0001 micron.

As the pore size gets smaller, more pressure will be needed to start the filtration process. Also surface properties play an important role. For a hydrophobic (water rejecting) surface more pressure will be needed than with a hydrophilic (water attracting) surface.

MF and UF are typical particle filters, whereas NF and RO change the chemical or ionic composition of the water, as for instance the removal of dissolved minerals. See the filtration spectrum underneath.

Filtration spectrum

Filtrationspectrum.jpg