Forward and pressure retarded osmosis: potential solutions for global challenges in energy and water supply

Abstract

Osmotically driven membrane processes (ODMP) have gained renewed interest in recent years and they might become a potential solution for the world's most challenging problems of water and energy scarcity. Though the concept of utilizing osmotic pressure difference between high and low salinity streams across semipermeable membranes has been explored for several decades, lack of optimal membranes and draw solutions hindered competition between forward osmosis (FO) and pressure retarded osmosis (PRO) with existing water purification and power generation technologies, respectively. Driven by growing global water scarcity and by energy cost and negative environmental impacts, novel membranes and draw solutions are being developed for ODMPs, mass and heat transfer in osmotic process are becoming better understood, and new applications of ODMPs are emerging. Therefore, OMDPs might become promising green technologies to provide clean water and clean energy from abundantly available renewable resources. This review focuses primarily on new insights into osmotic membrane transport mechanisms and on novel membranes and draw solutions that are currently being developed. Furthermore, the effects of operating conditions on the overall performance of osmotic membranes will be highlighted and future perspectives will be presented.

Removal of Trace Organic Chemicals and Performance of a Novel Hybrid Ultrafiltration-Osmotic Membrane Bioreactor

“…In FO, water diffuses through the semipermeable FO membrane from the feed solution to the DS; thus, the DS is diluted during FO and the feed becomes more concentrated. 29,30 To recover fresh water and maintain a constant DS concentration, FO is commonly coupled with a DS recovery process such as distillation, 31 membrane distillation (MD), 32,33 or RO. 34−36 In addition to reconcentrating the DS, a major benefit of using a hybrid FO-MD or FO-RO process is that two highly selective barriers are employed in series for removal of almost all dissolved feed constituents, including TOrCs.…”

Progress in Forward Osmosis Membrane Separation Process

“…[35,37] Membrane fouling leads to a water flux decline as a result of the increase of water transport resistance when solutes attach on membrane surface or diffuse into membrane interior. [39,43] Properties of membrane surface, such as hydrophilicity, charged state, roughness and structure, are closely related to the membrane fouling formation.…”

“…Given these merits, FO technology has been applied to a wide range of fields, such as seawater/brackish water desalination, [4,24,28] wastewater treatment, [8,[29][30][31] and many other areas. [32][33][34][35][36] Although FO exhibits a great potential in alleviating the issues caused by freshwater shortage, challenges, such as relatively low water permeability, high reverse solute diffusion, severe concentration polarization (CP), and membrane fouling, are still present in FO applications. [37][38][39] To eliminate these problems, exploration of appropriate semi-permeable FO membrane and draw solute is urgently needed.…”

Preparation and Characterization of Graphene Oxide / Cellulose Triacetate Forward Osmosis Membranes

“…The method proposed by Cathy et al was adopted to figure out the values of J w (water flux), J s (reverse salt flux), A (water permeability), B (salt permeability coefficient), S (structure parameter) [7]. …”