Biofouling can be a limiting factor in the application of membranes in water treatment. Biofouling can be considered as excessive biofilm growth. This process starts with the adhesion of microorganisms wich happens immediately after contact of the raw water with the membrane. It can be assumed that virtually all membrane systems working with non-
sterile water carry biofilms which influence the overall separation properties. Only if an individually given threshold of interference is met, "biofouling" occurs. A new anti-fouling strategy can be addressed as "biofilm management", limiting biofilm growth below that threshold. This can be performed by limitation of nutrients as nutrients must be regarded as potential biomass. Cleaning measures must address the binding forces which mediate cohesion and adhesion, basing on the additive effect of weak physico-chemical interactions and entanglement of macromolecules. Cleaning formulations should address all of theses forces.