Reverse osmosis (RO) has been widely applied in various water and wastewater treatment processes as a promising
membrane technology. However, RO membrane fouling is a global issue, which limits it operating flux, decreases
water production, increases power consumption and requires periodical membranes Cleaning-in-Place (CIP) procedure.
This may result in low effectiveness, high cost and adds environmental issues related to the CIP solutions disposal. Forward
osmosis (FO) or direct osmosis (DO) is the transport of water across a semi-permeable membrane from higher water
chemical potential side to lower water chemical potential side, which phenomenon was observed in 1748. The engineered
applications of FO/DO in membrane separation processes have been developed in food processing, wastewater treatment
and seawater/brackish water desalination. In recent years, DO has been increasingly attractive for RO fouling control as it
is highly efficient and environmentally friendly technique which is a new backwash technique via interval DO by intermittent
injection of the high salinity solution without stoppage of high pressure pump or interruption of the operational
process and allows keeping RO membrane continuously clean even in heavy bio-fouling conditions and operating RO
membranes at high flux. This paper provides the state-of-the-art of the physical principles and applications of DO for RO
fouling control as well as its strengths and limitations.
Direct Osmosis for Reverse Osmosis Fouling Control: Principles, Applications and Recent Developments