Cake-enhanced osmotic pressure

In RO, a colloidal deposit on the membrane introduces an additional resistance, Rf, and could also cause cake-enhanced concentration osmotic pressure (CEOP) [24]. The CEOP phenomenon is discussed in Section 6.3.4. Large-scale RO plants tend to be operated at a fixed production rate, requiring a fixed average flux. 

A porous cake layer may also affect membrane flux behavior by promoting a severe concentration polarization inside the unstirred cake layer [18], The enhanced concentration polarization can significantly increase the solute concentration at the membrane surface, and thus drastically increase the osmotic pressure at the membrane surface. 

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