The status of forward osmosis technology implementation

The current review appraises the status of forward osmosis (FO) technology implementation and prospective commercial exploitation through examination of its energy consumption and other key process attributes compared with classical desalination technologies. The outcomes of 15 studies conducted at pilot scale revealed the energy associated with the draw solution (DS) recovery to present a significant barrier to implementation of the technology, with a 40-50% decrease in energy consumption required for the DS recovery step for the process to successfully compete with classical reverse osmosis (RO) based processes. Against this, FO can be energetically favoured if deployed: (a) without the DS recovery step, i.e. osmotic concentration (CC) or fertilizer-drawn forward osmosis (FDFO), (b) in competition with evaporative desalination processes, or (c) for combined desalination and wastewater purification, when a comparatively low salinity stream is available for providing osmotic dilution (OD) of the saline feed water. Whilst these specific applications show some promise for the technology, there remains a paucity of pilot and demonstration-scale studies corroborating the theoretical energy benefit of the proposed technology configurations.