Direct Osmosis for Reverse Osmosis Fouling Control: Principles, Applications and Recent Developments

Jian-Jun Qin*, 1, Boris Liberman2, Kiran A. Kekre, Ado Gossan1
1 The Centre for Advanced Water Technology, PUB Consultants Pte Ltd;
2 IDE Technologies Ltd, Israel

© 2009 Qin et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Centre for Advanced Water Technology, PUB Consultants Pte Ltd, Israel; Tel: +65-63262914; Fax: +65-63262929; E-mail:


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.

Keywords: Backwash, direct osmosis, fouling control, reverse osmosis, salinity solution.