This review by an international team focuses on the present status of forward osmosis (FO) niches in two main areas: seawater desalination and wastewater reuse.
Specific applications for desalination and impaired-quality water treatment and reuse are described, and the benefits, advantages, challenges, costs, and knowledge gaps on FO hybrid systems are discussed.
FO can play a role as a bridge to integrate upstream and downstream water treatment processes, to reduce the energy consumption of the entire desalination or water recovery and reuse processes, thus achieving a sustainable solution for the water-energy nexus.
FO hybrid membrane systems are shown to have advantages over traditional membrane process like high-pressure reverse osmosis (RO) and nanofiltration (NF) for desalination and wastewater treatment:
- Chemical storage and feed water systems may be reduced for capital, operational and maintenance cost.
- Water quality is improved.
- Reduced process piping costs.
- More flexible treatment units.
- Higher overall sustainability of the desalination and wastewater treatment process.
Nevertheless, there are still major challenges to making FO systems into a commercially viable technology.
The most critical is the development of a high-flux membrane, capable of maintaining an elevated salt rejection and a reduced internal concentration polarisation effect. Another is the availability of appropriate draw solutions that are cost-effective and nontoxic, and which can be recirculated via an efficient recovery process.
This review article highlights the features of hybrid FO systems, and specifically provides the state-of-the-art on applications in the water industry in terms of a novel classification, based on the latest developments towards scaling up these systems.
Water Research, Volume 66, 1 December 2014, Pages 122–139.