THE FORWARD OSMOSIS DESALINATION: PROSPECTS FOR OVERCOMING CHALLENGES

Forward osmosis or direct osmosis (FO) is a membrane process driven by osmotic pressure, a natural phenomenon in which water passes through a relatively dilute feed solution (FS) into a relatively concentrated tensile solution (DS) from It passes through a semi-permeable membrane. Recently, direct osmosis has attracted widespread attention in many applications such as desalination, water treatment, wastewater treatment, liquid food processing, and etc. Compared to conventional pressurized membrane processes such as reverse osmosis (RO), direct osmosis has a lower tendency to deposit, easier cleaning, high water recovery, and lower equipment costs. Thin layer composite membranes (TFC), as the heart of the direct osmosis process, consist of an active thin layer on a porous layer. The top active layer is usually made of polymer polyamide (PA) thin film, which plays an important role in membrane selectivity. The thick porous substrate has a strong mechanical structure and provides sufficient membrane stability in the aqueous environment. Despite significant advances in the process of direct osmosis, there are still some technical challenges that prevent its widespread application. The direct osmosis process can be applied to the desalination of seawater with two main advantages: A) Its low energy consumption, B) Low fouling tendency compared to current desalination technologies.