The Effect of Concentration Polarization in the Process of Water Desalination by Forward Osmosis Method (Review)

 Energy and water are two of the most important challenging factors which human faces in the third millennium. Various methods of water desalination were employed that the applicability and industrialization of these methods are dependent on the optimization of the energy consumption and the appropriate efficiency. One of these methods is osmosis process that is divided into two sections: reverse osmosis and forward osmosis. Now, the reverse osmosis process is extensively used on industrial scale. The reverse osmosis process has more industrial applications than the forward osmosis. Currently, the forward osmosis process in commercialization path faces serious challenges. The factors that effect on the forward osmosis process include: properties of feed and draw solutions, concentration polarization, membrane orientation, selectivity and membrane ability to the rejection of solute on both sides of the membrane, creating a high osmotic pressure difference and easy regeneration capability of draw solution.

 In this article an overview of concentration polarization, its mathematical models and its reduction methods are studied.

 The most important strategies proposed by researchers for reducing concentration polarization is changing the membrane structure and optimizing process conditions and draw solution.

  Although the concentration polarization has a significant influence on the control and reduction of the water flux to pass through the membrane, it can reduce the water flux up to 80% of the initial water flux but with using appropriate operating conditions and optimizing membrane structure, the neglect results of it can reduce.