The method of quantitative qualification of reverse osmosis membranes from experimental data by using appropriate transport equations and defining membrane characteristics as transport parameters, such as pure water permeability, solute permeability and reflection coefficient is presented. Thereby the importance and the effect of concentration polarization phenomena are stressed, and its correction methods are shown. The character of membranes deteriorate gradually with time by various causes, such as compaction by the mechanical pressure, deposition of suspended matters or high molecular weight solutes on the membrane surface and chemical adsorption, oxidation or hydration of membrane materials. The quantitative estimation of some of such effects are discussed.
