The separation of substances with the help of membrane technology is a physical separation process. The big advantage of the membrane technology compared to other separation processes is based on the fact that to be separated materials can be changed neither biologically and chemically nor thermally. The membrane technology opens up new possibilities and increasingly replaces existing technologies like concentration by evaporation or chemical processes resp. can be combined with them. Basically many different membranes with different selectivities are available. In the membrane technology one distinguishes between reverse osmosis, nano filtration and micro filtration.