Abstract
Forward osmosis (FO) has become an evolving membrane separation technology to recover water due to its strong retention capacity, sustainable membrane fouling, etc. Although a good deal of research has been extensively investigated in the past decades, major challenges still remain as follows: (1) the novel FO membrane material properties, which significantly influence the fouling of the FO membranes, the intolerance reverse solute flux (RSF), the high concentration polarization (CP), and the low permeate flux; (2) novel draw solution preparation and utilization; (3) salinity build-up in the FO system; (4) the successful implementation of the FO process. This work critically reviews the last five years’ literature in development of the novel FO membrane material, structure in modification, and preparation, including comparison and analysis on the traditional and novel draw solutes coupled with their effects on FO performance; application in wastewater treatment, especially hybrid system and integrated FO system; fouling mechanism; and cleaning strategy as discussed in the literature. The current barriers of the research results in each hotspot and the areas that can be improved are also analyzed in detail. The research hotspots in the research and development of the novel membrane materials in various countries and regions have been compared in recent years, and the work of variation in pop research hotspots in the past 10 years has been analyzed and the ideas that fill the blank gaps also have been proposed.
Highlights
With the growth of population and economy, the water crisis posed by the increasing demand for water resources and aggravating water pollution has become one of the most serious problems in the 21st century
The results showed that the cost of NaCl-reverse osmosis (RO) scenario was the least, the system using dye mixture as draw solution (DS) produced 50% less sewage discharged to the municipal sewage treatment plant than NaCl-DS
The results demonstrated that the membrane foulant cake layer deposited faster in pressure retarded osmosis (PRO) mode than that in forward osmosis (FO) mode
Summary
With the growth of population and economy, the water crisis posed by the increasing demand for water resources and aggravating water pollution has become one of the most serious problems in the 21st century. Forward osmosis (FO), as an osmotic pressure-driven membrane process, demonstrated great application prospects to solve the global challenges of water and energy [2]. Pretreatment is not required for the treatment of complex wastewater Another significant advantage of FO is the low pollution propensity. The membrane fouling is dominated by reversible fouling which can be restored by simple hydraulic cleaning [8] This is a significant advantage when FO is applied to treat brine with high concentration. Despite the inherent advantages and broad application prospects, large-scale commercialization of the FO process has not been adequately possible due to some obstacles such as regeneration and separation of draw solutes, concentration polarization (CP) on the feed side, reverse solute diffusion (RSD), and membrane fouling [11]. The following contents are reviewed: (i) the latest improvement and the defaults in modification and preparation of FO membrane, the possible suggestions in the FO membrane preparation perfection; (ii) summary of the traditional draw solute specialties, classifications of the novel draw solutes discussed in the literatures; (iii) application of FO in wastewater treatment, especially salinity build-up in the FO system, the success implement of the FO process; (iv) recent developments on membrane fouling and cleaning strategy
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