The reduction in permeate flux due to fouling can be attributed to two mechanisms Concentration polarization is considered to be reversible and can be controlled in a membrane module by means of velocity adjustment

The reduction in permeate flux due to fouling can be attributed to two mechanisms Concentration polarization is considered to be reversible and can be controlled in a membrane module by means of velocity adjustment, pulsa- tion, ultrasound, or an electric field. Membrane fouling, on the other hand, is more complicated in that it is considered as a group of physical, chemical, and biological effects leading to irreversible loss of membrane permeability. Attempts to analyze the fouling phenomena, for example, have shown that the main factors are adsorption of feed components, clogging of pores, deposition of solids on the membrane surface accompanied by crystallization and compaction of the membrane structure,