Evaluation of draw solution effectiveness in a forward osmosis process

Abstract

© 2015 Balaban Desalination Publications. All rights reserved. This work investigates the effectiveness of sodium chloride and sucrose binary draw solutions in a forward osmosis pilot plant unit with either deionised or salt water feeds. Specifically, the effects of draw solution concentration on water flux through the membrane, the overall water recovery and the specific energy consumption of the unit are considered. For both feed types, sodium chloride draw solution exhibited a relatively high effectiveness in terms of all the measured performance indicators. Further, improvements in flux and recovery were also achievable with an increase in the sodium chloride (draw solution) concentration. In contrast, a sucrose-based draw solution led to a severe deterioration of the membrane performance that could not be effectively overcome by an increase in the draw solution concentration. This observation was attributed to the relatively large increase in the viscosity of the draw solution with increase in sucrose concentration. Interestingly, in the case of a salt water feed, an increase in the sucrose draw solution concentration led to a relatively small increase in flux and recovery, suggesting some complex but favourable interaction between the salt and sucrose due to the reverse diffusion of the salt into the draw solution

High-surface-area functionalized nanolaminated membranes for energy-efficient nanofiltration and desalination in forward osmosis

“…with an average flux of 1.25 LMH when tested under the same conditions-consistent with previous reports 38,39 . Compared with other 2D laminar membranes, the functionalized MoS2 membranes exhibit a higher water flux and superior salt rejection, exceeding the latest upper bound of state-of-the-art 2D laminar membranes (Fig.…”

Seawater Desalination: A Review of Forward Osmosis Technique, Its Challenges, and Future Prospects

“…Suitable DSs selection process broadly encompasses first, an initial screening of the functional DSs material often predicated upon its natural properties to evaluate for some basic integral components that influences an FO process including-water solubility, pH, speciation, osmotic pressure, and compatibility with the FO membrane. Consequently, a laboratory-scale test of the performances of the screened functional DSs material is often required, following which is a final evaluation of the functional DSs material's full-scale performance albeit further specific criteria may need to be evaluated depending on the targeted application [22,[39][40][41]. High water flux and low back solute flux, least possible reverse draw solutes flux, high solubility in water, optimum temperature, chemical stability, neutral pH, lower molecular weight, recyclability, low toxicity, fouling resistance, and chemical inertness towards the membrane employed had been described as some of the requite attributes for consideration as an ideal draw solute in forward osmosis processes [40,42,43].…”