Membrane separating processes are processes in which ions, molecules and particles in the sub-micron range can be separated with the aid of membrane solutions. Conventional separation processes, such as filtration, only achieve a separation limit of approx. 40 μm (gravel filter) up to approx. 0.2 μm. Membrane processes are pressure-driven process technologies, i.e. pressure must be exerted on the liquid to transport the medium through the membrane.