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The textile industry is one of the largest water consumers, and, as a result of its activity, it generates tons of wastewater. In this research, forward osmosis has been employed to tackle the critical need of treating textile wastewater. The HFFO2 membrane (Aquaporin) was used to process large volumes of real cotton dyeing wastewater, wool dyeing wastewater, and several types of textile end-of-pipe wastewater. In all cases, the permeate flux was between 6 and 8 L·h− 1 m− 2 during the major part of the process. The recovery of clean water from each wastewater surpassed 90 %, whereas the membrane rejected more than 87 % of total dissolved solids. As a result, textile dyes were concentrated on the feed side of the membrane, which enables their recovery and potential reutilization in a subsequent dying process, along with the reclaimed water. The HFFO2 membrane was efficiently cleaned by a backwash process, restoring the initial water flux. These results indicate the suitability of forward osmosis to reuse dyes and water from textile wastewater, reducing the environmental impact of this industry and favoring its sustainability.

Promising forward osmosis (FO) membrane desalination is a potentially viable energy‐efficient performance technology compared to other techniques. Searching for the ideal draw solute that creates high osmotic pressure difference and ease of regeneration is critical for water desalination using the FO system. However, many fundamental aspects still need to be adapted, such as needing more screening potential anions and cations based on the predictive method. The Group Contribution Method (GCM) was used in this study to predict the value of the van't Hoff factor denoted by (i). In the end, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([C4C1im][BF4]) was selected as a draw solution for later experimental work. [ABSTRACT FROM AUTHOR]

Desalination offers the potential to bridge the demand-supply gap in the increasing global freshwater scarcity, with the forward osmosis (FO) technique appearing as an attractive solution amongst the various desalination technologies. However, the significant energy demand encountered during the draw-solute recovery process in FO desalination is considered the major anathema amongst other contending factors for which the allure of FO as a desalination technology becomes questioned. Consequently, a potentially innovative draw solution (DS) regeneration strategy, enabling the circumvention of the energy requirements associated with the recovery stage in FO desalination, is evaluated. The direct solar thermal FO (DSTFO) desalination concept is predicated on engineering and applying solar absorptive DS to directly leverage solar energy for solute recovery without recourse to electric power. In advancing the DSTFO concept, this study fabricated and evaluated a novel and highly osmotic sodium functionalised carbon nanofibres (Na/CNF) DS having a high osmotic pressure (93.9 bar), a low reverse solute flux (RSF) of 0.24 gMH, and a photothermal conversion efficiency of 63.49%, resulting in an evaporation rate of 1.85 kg/m2/hr under 2 suns of solar radiation. The DSTFO strategy offers a low-cost solution for enhancing water recovery and decreasing energy use in FO desalination systems. [Display omitted] • Na/CNF DS nanofluid was successfully synthesised and utilised in DSTFO desalination. • DS nanofluid attained high osmotic pressure (93.9 bar) and low RSF (0.24 gMH). • DS achieved a 63.49% conversion efficiency and a 1.85 kg/m2/hr evaporation rate. • Desalinated water produced leveraging solar energy with minimal recourse to electricity. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the potential of utilizing both the draw and feed solutions resulting from fertilizer drawn forward osmosis for hydroponic crop cultivation. Synthetic brackish groundwater of 2500 ppm was used as the feed solution, whereas commercial hydroponic nutrients, sourced from a local supplier, were utilized as a draw solution. This study also investigated the potential of integrating nanofiltration with forward osmosis, but supplementing the water necessary for further dilution of draw solutions through nanofiltration. Two crops were selected, i.e., cherry tomatoes and spinach grown at different water salinities, for their economic values. The cherry tomatoes were grown in Deep Water Culture hydroponic systems, while the spinach was grown in Nutrient Film Technique systems. If this application is deemed feasible, it allows for providing a method to grow two different crops in areas associated with non-arable land and brackish groundwater. During desalination, it was observed that there were two groups of flux readings, the first with an average flux of 7 to 9 l/m2/h, and the other with an average flux of 4 to 6 l/m2/h. This was due to using the same draw solution twice; once to concentrate the feed solution to 5000 ppm, and then once more to concentrate the feed solution to 3500 ppm. It was found that while the 3500 ppm cherry tomatoes tables had the highest yield and highest number of tomatoes throughout the plants lifetime, tomatoes from freshwater tables on average weighed more by about 19%, while, on average, 5000 ppm tomatoes weighed less than 3500 ppm tomatoes by 10%. The results of the spinach demonstrated that while both control and experiment groups yielded similar number of leaves, the average yield per plant for the experiment group was higher than the control group (by 25%).

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final freshwater product. Three draw solutions, namely, MgCl2, NaCl, and C3H5NaO2, were initially tested against a synthetic water mimicking a pretreated produced water effluent having an osmotic pressure equal to 16.3 bar. MgCl2 was thus selected for high-recovery experiments. Different combinations of draw solution osmotic pressure (30, 40, 60, 80, and 120) and draw-to-feed initial volume ratios (1, 1.6, and 2.2) were tested at the laboratory scale, achieving recovery rates between roughly 35% and 70% and water fluxes between 4 and 8 L m−2h−1. One-dimensional, system-wide simulations deploying the analytical FO water flux equation were utilized to validate the experiments, investigate co-current and counter-current configurations, and understand the system potential. The diluted draw solutions were then transferred to nanofiltration to regenerate their original osmotic pressure. There, the highest observed rejection was 96.6% with an average flux of 21 L m−2h−1, when running the system to achieve 100% relative recovery.

Hyper-saline water streams, such as the produced water from the oil industry, cannot be treated via the conventional desalination method, such as reverse osmosis (RO), due to the extreme required pressure to overcome the osmotic pressure. This research investigates the effect of oil fouling and cleaning behaviors when the forward osmosis (FO) process is applied to treat hyper-saline-produced water. Synthetic produced water with total dissolved solids (TDS) concentration of 240 g/l (contained Na, Ca, Mg, Fe, Cl, SO4, and CO3 ions) and oil content of 100 ppm was used as a feed solution. Also, two draw solutions, namely: ammonium bicarbonate (NH4HCO3) and magnesium chloride (MgCl2) of concentrations 6 M and 4.8 M, respectively, were utilized for the FO operation. Results showed that the MgCl2 draw solution provided significantly higher water flux than NH4HCO3 due to MgCl2's high osmotic pressure and low scaling influence. Furthermore, the individual impact of oil was found to be low on the FO's water flux. However, a synergistic effect between the oil and inorganic scaling was noticed. SEM technique was used to comprehend the observation and analyze the fouling content. Although the feed was a highly polluted stream, it was found that osmotic backwashing can recover more than 90% of the initial flux. [ABSTRACT FROM AUTHOR]

The forward osmosis (FO) desalination process has recently acknowledged a lot of attention as a promising solution for reducing the disadvantages of existing desalination systems. This work aimed to investigate the effect of a selected liquid organic fertilizer a novel draw solution produced from "microalgae Spirulina platensis" on the biofouling mechanism of FO membrane. Different draw solution (DS) concentrations ranging 240–480 g/L were examined, obtained water flux ranging from 6.5 to 3.4 Lm2h-1. A high flux decline was observed when using higher DS concentrations due to fouling layer accumulated throughout the membrane area which lowers the effective osmotic pressure difference. Different cleaning strategies were examined. The biofouled membrane was cleaned on-line with deionized water (DI) and externally using ultrasound (US) and HCl. Baseline experiments were done to investigate the efficiency of the cleaning strategies. After cleaning using the deionized water (DI) water, it was found that the water flux progressed from 3.4 to 7 Lm2h-1, while when using acid cleaning the flux recovered to 15 Lm-2h-1. The efficacy and amount of foulant removed by each cleaning stage were assessed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). [ABSTRACT FROM AUTHOR]

This study investigated the potential of utilizing both the draw and feed solutions resulting from fertilizer drawn forward osmosis for hydroponic crop cultivation. Synthetic brackish groundwater of 2500 ppm was used as the feed solution, whereas commercial hydroponic nutrients, sourced from a local supplier, were utilized as a draw solution. This study also investigated the potential of integrating nanofiltration with forward osmosis, but supplementing the water necessary for further dilution of draw solutions through nanofiltration. Two crops were selected, i.e., cherry tomatoes and spinach grown at different water salinities, for their economic values. The cherry tomatoes were grown in Deep Water Culture hydroponic systems, while the spinach was grown in Nutrient Film Technique systems. If this application is deemed feasible, it allows for providing a method to grow two different crops in areas associated with non-arable land and brackish groundwater. During desalination, it was observed that there were two groups of flux readings, the first with an average flux of 7 to 9 l/m2/h, and the other with an average flux of 4 to 6 l/m2/h. This was due to using the same draw solution twice; once to concentrate the feed solution to 5000 ppm, and then once more to concentrate the feed solution to 3500 ppm. It was found that while the 3500 ppm cherry tomatoes tables had the highest yield and highest number of tomatoes throughout the plants lifetime, tomatoes from freshwater tables on average weighed more by about 19%, while, on average, 5000 ppm tomatoes weighed less than 3500 ppm tomatoes by 10%. The results of the spinach demonstrated that while both control and experiment groups yielded similar number of leaves, the average yield per plant for the experiment group was higher than the control group (by 25%). [ABSTRACT FROM AUTHOR]

Polyacrylic acid (PAA)-coated magnetic nanoparticles (MNP@PAA) were synthesized and evaluated as draw solutes in the forward osmosis (FO) process. MNP@PAA were synthesized by microwave irradiation and chemical co-precipitation from aqueous solutions of Fe2+ and Fe3+ salts. The results showed that the synthesized MNPs have spherical shapes of maghemite Fe2O3 and superparamagnetic properties, which allow draw solution (DS) recovery using an external magnetic field. Synthesized MNP, coated with PAA, yielded an osmotic pressure of ~12.8 bar at a 0.7% concentration, resulting in an initial water flux of 8.1 LMH. The MNP@PAA particles were captured by an external magnetic field, rinsed in ethanol, and re-concentrated as DS in repetitive FO experiments with deionized water as a feed solution (FS). The osmotic pressure of the re-concentrated DS was 4.1 bar at a 0.35% concentration, resulting in an initial water flux of 2.1 LMH. Taken together, the results show the feasibility of using MNP@PAA particles as draw solutes. [ABSTRACT FROM AUTHOR]

Microalgae shows a high potential to produce biofuel and forward osmosis (FO) has been proposed as a promising dewatering process for algal biomass separation from water. However, the effect of reverse salt flux (RSF) on algal biomass during the dewatering process using FO has not been completely explored. This study was to investigate the effect of different types of salt and their concentrations on algal biomass in terms of conductivity, settling velocity, and lipid contents in FS during a simulated FO-driven dewatering of Chlorella vulgaris microalgae. Three draw solution (DS) salts (NaCl, KCl and NH4Cl) were evaluated in RSF-simulating batch tests. The salt diffusion from the DS to the algal feed solution (FS) caused a static growth of algal biomass while increasing lipid content up to 14.8% at 8 mM NH4Cl. With the addition of the different salts, pH was maintained to the optimal algal thriving range (7.2–10.6), but the presence of salt stressed the algal cells and inhibited photosynthesis and algal growth within the experimental conditions. The settling velocity of the algal cells improved with the increase of salt content from 8 to 80 mM of each DS. It seemed that cell division could be accelerated in the presence of NH4Cl, and microscopic images showed a change in the algal cell size distribution, which may negatively affect algal settleability. DS salt in an FO-algal harvesting system should be selected based on the final algal properties and constituents required. [ABSTRACT FROM AUTHOR]

Thermoresponsive magnetic ionic liquids (TMILs) showing lower critical solution temperature (LCST)-behavior were fabricated and utilized as forward osmosis (FO) draw solutes for seawater desalination. The MILs, 8-alkyl-1,8-diazabicyclo[5.4.0]undec‑7-ene bromotrichloroferrate (DBU-R[FeBrCl3], or d-R-FeX4) with different alkyl chain lengths (R = C4H9, C6H13, C7H15, or C8H17), exhibited tunable LCSTs from 30 to 65 °C by varying the chain length and the solution concentration. Upon heating above their LCSTs, more than 43% of the TMILs could be magnetically extracted via phase separation, demonstrating a facile magnet-assisted draw solution regeneration approach. In addition, an aqueous solution containing 25 wt% D-Bu-FeX4 was able to achieve a water flux as high as 4.5 L m−2 h−1 (LMH) in desalinating seawater. Their ionic nature, together with unique thermo- and magnetic-responsive behaviors, make them promising candidates as ideal FO draw solutes for desalination and wastewater reclamation.

Forward osmosis technology was evaluated for treating evaporator brine stream from a petrochemical industry at bench scale using ammonium bicarbonate as a draw solution. Calcium carbonate scaling that forms from the interaction between the calcium ions in the feed solution and carbonate ions from the draw solution (reverse salt diffusion) leads to the reduction in water flux and water recoveries achievable (feed TDS concentration of ~60 000 mg·L−1, calcium ~545 mg·L−1 and draw solution (ammonium bicarbonate) concentration of ~240 000 mg·L−1). Fouling can be prevented by softening the feedwater before it is treated in forward osmosis. Without calcium and magnesium, permeate fluxes and water recoveries of up to 6 L·m−2·h−1 and 60%, respectively, could be achieved. It was also observed in this study that the concentration of the calcium ions in the feed does have an impact on the formation of the calcium carbonate scale, implying that some hardness can be tolerated in the feed to the forward osmosis process. It can, therefore, be concluded that without some hardness removal, ammonium bicarbonate draw solution is not suitable for treating concentrated brine streams (e.g., evaporator brine) that contain a high concentration of calcium ions. FO technology using ammonium bicarbonate as a draw solution can be considered an alternative technology to treat concentrated brine streams from inland industries, provided some pre-treatment to remove scaling precursors such as calcium is incorporated in the flow scheme. [ABSTRACT FROM AUTHOR]

The major scope of this study is the fabrication and development of a substrate and polyamide rejection layer for an efficient thin-film hydrophilic composite forward osmosis (TFC-FO) membrane. Fabrication of a thin-film nanocomposite forward osmosis membrane employing interfacial polymerization and modification of substrate characteristics using titanium dioxide (TiO2) nanoparticles as additives (TFNC-FO) are studied. Characterizations of the prepared TFC-FO and TFNC-FO membranes were determined. The morphologies of cross-section, upper and bottom surfaces for the TFC-FO and TFNC-FO membranes were studied using scanning electron microscopy (SEM). Energy-dispersive X-ray (EDX) spectroscopy was used to examine the compositions of different elements for both membranes. The hydrophilicity of the prepared TFC-FO and TFNC-FO membranes was investigated using the measurement of the contact angle test. A Fourier Transform Infrared (FT-IR) spectrophotometer was used to observe the existing functional groups of the TFC-FO and TFNC-FO membranes. The thermal stability of the membrane was evaluated via thermogravimetric analysis (TGA). The overall performance of TFC-FO membranes was evaluated with and without adding TiO2 nanoparticles through different parameters, such as membrane flux, initial feed concentration, draw solution concentrations, reverse solute fluxes, membrane permeabilities, and finally, the effect of FO membrane orientations. FO membrane performance was successfully enhanced by adding different concentrations of TiO2 nanoparticles from 0.5 to 1.5 wt%. The findings indicated that an increase in the concentration from 0.5 to 1 wt% leads to a clear increase in both the porosity and hydrophilicity of the nanocomposite substrate and consequently, an increase in the water flux. However, further increasing the concentration of TiO2 nanoparticles to more than 1 wt% affects the membrane performance. HIGHLIGHTS Preparation of a TFNC-FO membrane.; Incorporating TiO2 nanoparticles into polysulfone membrane matrix.; Evaluation of FO performance.; FO membrane permeability.; Characterization of the synthetic FO membranes.;

Drawing on the collective insights and findings of prior researchers in the field of draw solution (DS) exploration, we have synthesized agarose-coated Fe 3 O 4 magnetic nanoparticles (ACMNPs) with precise control at each stage to achieve superparamagnetic properties. This allows them to be separated from the DS at the end of the forward osmosis (FO) desalination process using a magnet, thereby producing fresh water. Furthermore, coating the magnetic nanoparticles (MNPs) with agarose, a superhydrophilic polymer, increases their solubility in an agarose-shell/Fe 3 O 4 -core structure. This approach represents the culmination of our efforts and ensures alignment with our desired objectives. In the experimental phase, Fe 3 O 4 MNPs and ACMNPs were compared at different concentrations as draw solutes in the FO desalination process. The results demonstrated the effect of the agarose coating on the hydrophilicity of the ACMNPs. Ultimately, the findings indicate that MNPs, when appropriately coated with agarose, can be used as effective draw solutes in FO systems. Easily recyclable, powerful hydrophile and strong osmotic pressure generator draw solutes. [Display omitted] • The DS is the main factor in creating a chemical potential difference on both sides of the FO desalination membrane. • The size of nanoparticles affects their solubility and magnetic properties. • ACMNPs cores exhibit superparamagnetic properties. • Agarose is highly hydrophilic and soluble in water. • An agarose coating on Fe 3 O 4 MNPs increases J w in the process. [ABSTRACT FROM AUTHOR]

The demand to recover value-added resource is intensified due to the accelerating growth of resource waste with wastewater discharge. Here we design pH-responsive sodium salts of an imidazole-based ionic solid (im-IS), im-IS-Na and im-IS-2Na, as draw solutes for forward osmosis (FO) to achieve resource recovery. im-IS-Na and im-IS-2Na both have an expanded structure and contain multiple ionic moieties. These attributes make them generate a sufficient driving force for FO separation and negligible solute losses. Consequently, im-IS-Na and im-IS-2Na at 1.0 M produce pure water fluxes of 27.5 LMH and 32.0 LMH, respectively, increased up to 128 % relative to those of conventional draw solutes. im-IS-Na can concentrate the glycine-containing solution efficiently with a water flux of 17.6 LMH, 183 % and 25 % higher than those of NaCl and NH 4 HCO 3 , separately. Particularly, im-IS-Na preserves the glycine product intact, whereas NaCl and NH 4 HCO 3 either denature or contaminate it resulting from their severe reverse diffusion. im-IS-Na and im-IS-2Na are conveniently regenerated by pH regulation involving no organic solvent and external pressure which are commonly used in recycling other draw solutes. im-IS-Na and im-IS-2Na thus demonstrate their superiority as FO draw solutes to recover value-added resources. FO-based hybrid system for simultaneous water reclamation and glycine recovery. [Display omitted] • Smart imidazole-based im-IS-Na and im-IS-2Na materials are designed for FO draw solutes (DS). • im-IS-Na and im-IS-2Na induce higher fluxes with negligible losses than conventional DS in FO. • The im-IS-Na facilitated FO system achieves simultaneous water reclamation and resource recovery. • im-IS-Na and im-IS-2Na are regenerated by pH regulation and reusable for FO separation. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO) is a membrane separation process that harnesses a concentrated draw solution (DS) to extract fresh water from the feed solution (FS) through a semi-permeable membrane. The selection of an appropriate DS and the efficient DS regeneration techniques are the two pivotal challenges in making FO commercially and economically viable. Here, we aim to review the draw solute recovery techniques including thermal regeneration, nanofiltration, ultrafiltration, magnetic separation, precipitation, integrated processes, and direct DS utilization without recovery. Besides the above-mentioned traditional techniques, recently evolved techniques including progressive freezing, pH regulation, and other innovative approaches (including integrated techniques) were critically reviewed focussing on the development of an integrated recovery strategy, material advancements, challenges, and developments to improve the regeneration efficiency. These improvements will help towards achieving the sixth Sustainable Development Goal (i.e., Clean Water and Sanitation) developed by The United Nations (UN). Furthermore, specific applications of these novel integrated recovery techniques in various sectors including pharmacy, fertigation, and aquaculture were discussed. Finally, we offer suggestions for future research and development to enable the widespread application of FO in wastewater treatment. [Display omitted] • Advancements (progressive freezing and pH regulation) in DS recovery are reviewed. • Recent integrated methods including NF-MD and pH-MF-precipitation are discussed. • Best recovery method for various DS with respect to characteristics are recommended. • Draw solutions which no need any recovery are reviewed focusing on application. • Economics of DS in FO and future research of DS recovery in FO and are discussed. [ABSTRACT FROM AUTHOR]

In this study, D-Xylose coated MNPs were synthesized and used as draw agent in forward osmosis (FO) process for water purification. Response surface methodology (RSM) was utilized for the design and optimization of synthesis parameters. In order to characterize the synthesized MNPs, FTIR, TEM, VSM, and UV characterization techniques were performed. The effect of independent parameters including D-Xylose mass, MNPs mass, and synthesis time on the osmotic pressure was investigated. Based on the optimization results, the osmotic pressure of a 2 wt./v% draw solution using 2.66 g D-Xylose, 0.13 g MNPs, and a 7.11 h synthesis time was 0.81 bar as the highest value. Using D-Xylose coated MNPs as draw agent and deionized water as the feed, the initial FO water flux was 2.98 LMH. Reusing the recovered MNP draw agent in two more consecutive tests resulted in the reduction of water flux to 2.68 and 2.30 LMH, respectively. Moreover, using 0.01 M NaCl solution as the feed, the initial water flux was reported as 1.3 LMH. To remove the draw agents from suspension, external magnetic field was applied to obtain a water turbidity of 0.08 NTU. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO), a green and economical membrane technology driven by a natural concentration gradient, has attracted increasing attention for wastewater treatment because it consumes less energy and removes large amounts of pollutants. In this research, an approach based on an FO mechanism that could improve the concentration of organic pollutants in wastewater collected from grass carp ponds was proposed. The wastewater serving as a feed solution (FS) was concentrated by FO, and sucrose was used as a draw solution (DS). The multiple chemical oxygen demand (COD) variation, the water flux, and the reverse solute flux during the FO process were investigated. The results indicated that the water flux and the reverse solute flux had similar trends in the processing of batch experiments 1–8, and the concentrating multiple of organic contaminants reached a maximum of 3.5 in the whole study. In addition, membrane fouling was studied via a scanning electron microscope (SEM), and a loose cake layer was deposited on the membrane surface. Moreover, findings from energy dispersive scanning (EDS) analysis showed that the fouling substances in the support layer of the membrane were mainly organic compounds and silica. In contrast, the dominant contaminants of the active layer contained several microelements (such as K and Ca) in addition to organic compounds. Three-dimensional (3D) fluorescence analysis confirmed that the FS components could enter the DS and the chemical components of the sucrose solution could also enter the FS. The findings of this study provide a new view on selecting a DS and protecting the aquaculture environment. [ABSTRACT FROM AUTHOR]

This review considers the forward osmosis (FO) membrane process as one of the feasible solutions for water desalination. Different aspects related to the FO process are reviewed with an emphasis on ultrasound assisted FO membrane processes. The different types of membranes used in FO are also reviewed and discussed; thus, their configuration, structure and applications are considered. Coupling ultrasound with FO enhances water flux through the membrane under certain conditions. In addition, this review addresses questions related to implementation of an ultrasound/FO system for seawater desalination, such as the impact on fouling, flow configuration, and location of fouling. Finally, the mechanisms for the impact of ultrasound on FO membranes are discussed and future research directions are suggested. [ABSTRACT FROM AUTHOR]

The use of forward osmosis (FO) membranes for simultaneous thickening and digestion of waste activated sludge (WAS) (FO-MSTD) has recently garnered significant interest. However, a major challenge hindering the widespread adoption of the FO-MSTD process is severe membrane fouling, which results from increasing sludge concentrations and deteriorating sludge properties. In response, this study proposes a novel FO membrane fouling control strategy based on the critical flux concept, involving a variable draw solution (DS) operating mode. Two operating modes were examined based on the critical flux behavior of the FO membrane: a constant DS concentration mode (with a fixed DS concentration of 1.5 M, referred to as Constant DS1.5) and a variable DS concentration mode (with varying DS concentrations at different operational stages, referred to as Variable DS1.5-1.0 and Variable DS1.5-0.75). Over 21 days of operation, the MLSS concentrations of WAS in the Constant DS1.5, Variable DS1.5-1.0, and Variable DS1.5-0.75 reactors increased from initial values of 3.46, 3.88, and 4.20 g/L to 35.2, 31.5, and 29.2 g/L, respectively. Concurrently, the cumulative digestion rates of MLVSS in the three FO-MSTD processes reached 29.3 %, 29.0 %, and 36.3 %, respectively. After adjusting the DS concentration, the FO membrane flux decay rates for Constant DS1.5, Variable DS1.5-1.0, and Variable DS1.5-0.75 were 57.7 %, 49.4 %, and 13.8 %, respectively. In addition to experiencing a lower flux decline, the Variable DS1.5–0.75 mode achieved a significantly higher flux recovery rate of 98.5 % compared to the other two modes. Moreover, the biovolume of proteins and microorganisms in the membrane fouling layer decreased by 85.2 % and 72.7 %, respectively, in the Variable DS1.5–0.75 mode compared to the Constant DS1.5 mode. These findings indicate that operating with a DS below the critical concentration can significantly improve the reversibility of membrane fouling and reduce the presence of organic and biological foulants in the fouling layer, thereby mitigating membrane fouling in the FO-MSTD reactor. [Display omitted] • Critical flux-based fouling control method was proposed for FO membrane. • Critical flux of FO membrane varied under different sludge concentrations. • Variable DS operation mode alleviated FO membrane fouling during sludge treatment. • Below critical flux contributed to minimizing biofoulants deposition. • Below critical flux was beneficial for the recovery of FO membrane flux. [ABSTRACT FROM AUTHOR]

[Display omitted] • The formation mechanism of salt accumulation is elucidated. • Effects of salt accumulation is analyzed. • Methods to improve the salt tolerance of OMBR is proposed. • Strategies of inhibiting salt accumulation are summarized. The osmotic membrane bioreactor (OMBR) is a novel wastewater treatment and resource recovery technology combining forward osmosis (FO) and membrane bioreactor. It has attracted attention for its low energy consumption and high contaminant removal performance. However, in the long-term operation, OMBR faces the problem of salt accumulation due to high salt rejection and reverse salt flux, which affects microbial activity and contaminants removal efficiency. This review analyzed the feasibility of screening salt-tolerant microorganisms and determining salinity thresholds to improve the salt tolerance of OMBR. Combined with recent research, the inhibition strategies for salt accumulation were reviewed, including the draw solution, FO membrane, operating conditions and coupling with other systems. It is hoped to provide a theoretical basis and practical guidance for the further development of OMBR. Finally, future research directions were prospected. This review provides new insights for achieving stable operation of OMBR and promotes its wide application. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO) is a promising technology for efficient water reclamation at low operating costs. It has shown potential in producing fresh water from seawater; however, the regeneration of the diluted draw solution (DS) still holds back further development. Thermo-responsive polymers, especially polyalkylene glycol (PAG) based copolymers with hydrophilic ethylene oxide and hydrophobic propylene oxide units, have shown suitability as DSs in FO using low-temperature waste heat to regenerate the DS. In this study, we explored five commercially available copolymers: Pluronic® PE 6400, Pluronic® L-35, Pluronic® RPE 1740, Unilube® 50 MB-26, and Polycerin® 55GI-2601 as DSs in a laboratory FO setup, with DI water as the feed solution (FS). The water flux and reverse solute flux varied from 1.5 to 2.0 L·m−2·h−1 and from 0.04 to 0.4 g·m−2·h−1, respectively. Furthermore, all polymer solutions showed the ability to be recovered and reused using temperatures below 100 °C. Therefore, the tested PAGs turned out to be promising as draw solutions for FO systems that utilize low-grade waste heat. The re-usage in FO was shown for regenerated Pluronic® L-35 through a three-step experiment where its recovery was 91.1 %, 93.1 %, and 91.9 % for each FO cycle, respectively. • Polyalkylene glycol (PAG) based copolymers have shown suitability as DSs in FO. • All PAGs showed the ability to be recovered and reused using temperatures below 100 °C. • Some indication of membrane fouling caused by high-concentration PAG solutions [ABSTRACT FROM AUTHOR]

This study proposes a novel hybrid process that integrates direct air capture (DAC) and pressure-retarded osmosis (PRO) to address high water and energy demands of the DAC process and achieve simultaneous decarbonization and energy production. To explore the PRO performance in this hybrid process, membrane fouling behaviors were investigated by employing forward osmosis membranes in the PRO mode with various Na- and K-based draw solutions that simulated hydroxide-based CO 2 -captured solutions. Especially calcium (Ca2+) and alginate were dosed into the draw solutions as representatives of scaling precursor and organic foulants during long-term DAC-PRO operation respectively. The results revealed that (1) the presence of calcium in the NaHCO 3 and KHCO 3 draw solutions formed CaCO 3 precipitates, whose amounts, morphologies, and particle size were associated with the dosed Ca2+ concentration and alkali solution type. (2) Higher calcium amounts in the NaHCO 3 and KHCO 3 draw solutions promoted more deposition of rhombohedral CaCO 3 crystals on the membrane, leading to a lower water flux (J w) and higher reverse salt flux (J s) due to increased hydraulic resistance and cake-layer-enhanced concentration polarization. (3) Dosing calcium (40 mM) into a mixture of H C O 3 - and C O 3 2 - draw solution resulted in accumulation of irregular-shape CaCO 3 crystals on the membrane and an increase of J w , possibly relating to the increased membrane hydrophilicity due to decreased solubility of the solute at a higher pH level. (4) The addition of alginate into calcium-dosed (40 mM) draw solutions did not influence J w and J s but increased deposited foulants. This suggests that deposited alginate may loosely attach to CaCO 3 crystals, instead of creating a dense fouling layer by bridging with Ca2+. [ABSTRACT FROM AUTHOR]

This research project aims at investigating the performance of hydroponic nutrient solutions as draw solutions for desalination using the fertilizer drawn forward osmosis (FDFO) process. Six different lettuce and leafy greens hydroponic nutrient stock solutions were prepared according to the literature and used in this study and tested on a bench-scale forward osmosis unit as draw solutions for the process. The feed solution for the process was deionized water mixed with NaCl in different concentrations, to represent different salinities of brackish groundwater. The draw efficiency of each solution was measured based on water flux, specific reverse solute flux, water recovery, and salt rejection. It was concluded that of the six tested nutrient solutions, the "Resh Florida, California" solution is the recommended solution to be used as draw solution for fertilizer drawn forward osmosis, due to its high performance in terms of water recovery (15.75%), flux (11 L/m2/h), salt rejection (92%), and SRSF (highest recorded SRSF for a specific ion (SO42−) was 7.3 g/L), as well as its low cost, relative to the other highly performing draw solution "Chekli" ($1.07/L vs. $3.73/L). [ABSTRACT FROM AUTHOR]

The produced water is considered one of the largest waste streams in the oil and gas industries. Untreated produced water discharge damages the environment. Forward osmosis utilizes a dilute solution to concentrate contaminated streams to treat produced water. This paper tried to shed some light on forward osmosis's potential in treating produced water, measuring forward osmosis commercial membrane's effectiveness in treating produced water feed taken from two different points in an oil and gas facility in Malaysia. The rejection for chemical oxygen demand and boron was greater than 80 %, and a considerable decrease in forward osmosis flux was observed. The corrugated plate interceptor's inlet feed decreased by 73 % relative to the initial flux, while it decreased by 52.5 % for equalization tank feed. Design expert® was used to optimize the process using a one‐factor experimental design. The regression models indicated a good fit of model. The R2 was 0.9393 and 0.9888 for corrugated plate interceptor's inlet, and the equalization tank produced water, respectively. The optimization results concluded a 20 % draw solution concentration with the desirability of 0.927 and 0.987 for two feed waters. [ABSTRACT FROM AUTHOR]

Forward osmosis is an emerging membrane technology in water desalination. In this study, desalination of saline water via forward osmosis was investigated using a new magnetic osmotic agent. For this purpose, Fe3O4 nanoparticles covalently functionalised with tri-sodium citrate was synthesised and characterised. The structural examinations revealed that the sodium citrate had been immobilised onto the magnetic nanoparticles. The highest water flux was obtained 17.1 L M−2 h (LMH) per 80 g L−1 osmotic agent solution against deionised water, while the ratio of salt flux to water flux was very low (0.088 g L−1). The osmotic solution was evaluated for saline water desalination using different concentrations of sodium chloride (NaCl) as feed solutions. The average water fluxes of 6.2, 4.5, and 2.7 LMH was obtained for 0.1, 0.2, and 0.5 M salt solutions, respectively. The magnetic osmotic agent was separated by a magnet and re-used for several times without considerable decrease in the water flux. [ABSTRACT FROM AUTHOR]

The feasibility of PES membrane with hydrophobic property, high glass transition temperature, excellent thermal and chemical stability, with good mechanical properties as porous polymeric support was studied in membrane distillation (MD) process. Several strategies were considered and investigated to decrease membrane wetting by keeping up salt rejection and also to improve the permeate flux of PES membrane in the MD process. From this point of view, hydrophobic PMHS polymer with different concentrations was used as a surface coating solution. The morphology and structure of prepared membranes were evaluated by AFM and FESEM analyses. After coating modification, the salt rejection was increased up to 98% and the contact angle was changed from 65.11° to >100.2°. To increase the water flux, the effect of feed temperature (55 °C and 75 °C) and draw solution utilization containing magnetic nanoparticle (Fe3O4) was investigated. Using draw solution provided a driving force from feed solution to permeate side and increased average permeate flux from 2.9 kg/m2·h to 6.9 kg/m2·h in the 0.06 g/l of draw solute concentration. It improved permeate flux and salt rejection simultaneously. [ABSTRACT FROM AUTHOR]

This study aims to optimize the operating conditions of the forward osmosis (FO) process by introducing thermo-responsive ionic liquids (TRILs) namely l-butyl-3-methylimidazolium tetrafluoroborate ([BmimlfBFJ) as a draw solution for seawater desalination applications. The influence of the operation parameters, such as the feed and draw flowrate (60-300 ml/min), draw solution concentration (0.6-3.0 M), temperature (25-50 °C), and type of flow with feed concentration using artificial seawater (0.6 M NaCl). The interaction between parameters has been specified using fractional factorial design (FrFD). The draw solution concentration and the interactions between draw and feed flowrate were the most significant factors in achieving high water flux 5.1 LMH. Besides that, the draw flowrate and the interaction of both draw and feed flowrate give high significance toward adverse effects (such as concentration polarization), which is good to obtain low reverse salt at 1.3 gMH. Use the desirability function (DF) to obtain the highest water flux of 5.04 LMH and the lowest reverse salt flux of 1.71 gMH, with a desirability of 0.95. The optimal condition for FO performance is 300 ml/min feed and draw flowrate with 3.0 M draw solution at 25 °C and co-current flow. [ABSTRACT FROM AUTHOR]

As draw solute is the core element of forward osmosis (FO) technology, here Li-Bet-Tf2N synthesized from a customized ionic liquid betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]) and Li2CO3 recovered from lithium-ion battery (LIB) wastes is proposed as a novel draw solute to treat Li+-containing wastewater from LIB manufacturing through FO filtration. Having high dissociation ability and an extended structure, Li-Bet-Tf2N generates a sufficiently high osmotic pressure to drive the FO filtration efficiently along with insignificant reverse solute diffusion. Li-Bet-Tf2N produces a water flux of 21.3 L·(m2·h)−1 at 1.0 mol·L−1 against deionized water, surpassing conventional NaCl and MgCl2 draw solutes with a higher water recovery efficiency and a smaller solute loss. Li-Bet-Tf2N induces a more stable and higher water permeation flux with a 10.0% water flux decline than NaCl and MgCl2 for which the water fluxes decline 16.7% and 16.4%, respectively, during the treatment of 2000 mg·L−1 Li+-containing wastewater for 12 h. More remarkably, unlike other draw solutes which require intensive energy input and complicated processes in recycling, Li-Bet-Tf2N is easily separated from water via solvent extraction. Reproducible results are achieved with the recycled Li-Bet-Tf2N. Li-Bet-Tf2N thus demonstrates a novel class of draw solute with great potentials to treat wastewater economically. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO) is a low-energy treatment process driven by osmosis to induce the separation of water from dissolved solutes/foulants through the membrane in hydraulic pressure absence while retaining all of these materials on the other side. All these advantages make it an alternative process to reduce the disadvantages of traditional desalination processes. However, several critical fundamentals still require more attention for understanding them, most notably the synthesis of novel membranes that offer a support layer with high flux and an active layer with high water permeability and solute rejection from both solutions at the same time, and a novel draw solution which provides low solute flux, high water flux, and easy regeneration. This work reviews the fundamentals controlling the FO process performance such as the role of the active layer and substrate and advances in the modification of FO membranes utilizing nanomaterials. Then, other aspects that affect the performance of FO are further summarized, including types of draw solutions and the role of operating conditions. Finally, challenges associated with the FO process, such as concentration polarization (CP), membrane fouling, and reverse solute diffusion (RSD) were analyzed by defining their causes and how to mitigate them. Moreover, factors affecting the energy consumption of the FO system were discussed and compared with reverse osmosis (RO). This review will provide in-depth details about FO technology, the issues it faces, and potential solutions to those issues to help the scientific researcher facilitate a full understanding of FO technology.

The applicability of ionic liquids (ILs) as the draw solute in a forward osmosis (FO) system was investigated through a study on the effect of the structural change of the anion on the FO performance. This study evaluated ILs composed of tetrabutylphosphonium cation ([P4444]+) and benzenesulfonate anion ([BS]−), para-position alkyl-substituted benzenesulfonate anions (p-methylbenzenesulfonate ([MBS]−) and p-ethylbenzenesulfonate ([EBS−]), and methanesulfonate anion ([MS]−). The analysis of the thermo-responsive properties suggested that the [P4444][MBS] and [P4444][EBS] ILs have lower critical solution temperatures (LCSTs), which play a beneficial role in terms of the reusability of the draw solute from the diluted draw solutions after the water permeation process. At 20 wt% of an aqueous solution, the LCSTs of [P4444][MBS] and [P4444][EBS] were approximately 36 °C and 25 °C, respectively. The water flux and reverse solute flux of the [P4444][MBS] aqueous solution with higher osmolality than [P4444][EBS] were 7.36 LMH and 5.89 gMH in the active-layer facing the draw solution (AL-DS) mode at osmotic pressure of 25 atm (20 wt% solution), respectively. These results indicate that the [P4444]+-based ionic structured materials with LCST are practically advantageous for application as draw solutes.

Forward osmosis (FO) is a promising technology for the treatment of complex water and wastewater streams. Studies around FO are focusing on identifying potential applications and on overcoming its technological limitations. Another important aspect to be addressed is the environmental sustainability of FO. With the aim to partially fill this gap, this study presents a life cycle analysis (LCA) of a potential full-scale FO system. From a purely environmental standpoint, results suggest that significantly higher impacts would be associated with the deployment of thermolytic, organic, and fertilizer-based draw solutes, compared to more accessible inorganic compounds. The influent draw osmotic pressure in FO influences the design of the real-scale filtration system and in turn its environmental sustainability. In systems combining FO with a pressure-driven membrane process to recover the draw solute (reverse osmosis or nanofiltration), the environmental sustainability is governed by a trade-off between the energy required by the regeneration step and the draw solution management. With the deployment of environmentally sustainable draw solutes (e.g., NaCl, Na2SO4), the impacts of the FO-based coupled system are almost completely associated to the energy required to run the downstream recovery step. On the contrary, the management of the draw solution, i.e., its replacement and the required additions due to potential losses during the filtration cycles, plays a dominant role in the environmental burdens associated with FO-based systems exploiting less sustainable draw solute, such as MgCl2.

This paper presents the optimization of synthesis of gelatin-coated magnetite nanoparticles (MNPs) and their application as a draw solute in forward osmosis (FO) process. Persicaria bistorta root extract is used as the gelatin crosslinker, and its efficiency is compared with glutaraldehyde as a common crosslinker. Also, the impact of the concentration of gelatin and the draw solution on the osmotic pressure of the produced draw solution has been investigated using response surface methodology. Using Persicaria bistorta root extract as the crosslinker in the optimized conditions, the highest osmotic pressure (1.01 bar) was achieved in a concentration of 7.7%w/v and 14246 mg/l for gelatin and draw solution, respectively. Using glutaraldehyde under the same conditions resulted in osmotic pressure of 1.06 bar which is very close to the pressure found for Persicaria bistorta root extract (1.01 bar), confirming the benefit of the latter as a gelatin crosslinker. Further, using a solution with gelatin-coated MNPs as the draw solution, deionized water as the feed solution, and an osmotic pressure difference of 1.5 in the FO process generated an initial water flux of 1.54 LMH. By repeating the process in nine more cycles, the initial water flux was reduced to 0.365 LMH. These experiments confirm the as-prepared gelatin-MNPs as a promising draw solution in the FO process. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO) has recently gained interest in wastewater treatment and seawater and brackish groundwater desalination. Response surface methodology (RSM) was used for the prediction and optimization of the FO process using a low‐concentration draw solution (DS). The process variables were the feed solution (FS) temperature, the DS concentration, and the FS concentration. These variables were subjected to regression models and had R2 values > 0.9. The FS temperature had a negative impact on the weight transfer from the DS, while the FS and DS concentrations had a direct correlation with the performance. At an FS temperature of 29 °C, the DS at 13 986 mg L−1 and the FS at 1702 mg L−1 produced the best results, thereby lowering the DS regeneration costs. Under this condition, the models were experimentally validated, confirming the predictive ability of the models. [ABSTRACT FROM AUTHOR]

[Display omitted] Two strategies were investigated for salinity build up prevention in osmotic membrane bioreactors (OMBR) treating a real refinery wastewater. Firstly, a solute with lower diffusivity (MgCl 2 , for 102 days) was used. The impact on the microbiological activity was lower, which favored the recalcitrant compounds degradation. However, without salinity relief, the mixed liquor (ML) salinity increased, impacting the forward osmosis (FO) flux (0.18 L/m2h). Secondly, an ultrafiltration (UF) membrane was submerged within the ML and the draw solution (DS) replaced to NaCl. The ML conductivity was stable along 330 days without a severe flux decay (1.07 L/m2h). Nonetheless, the reverse NaCl flux had a higher impact on the microbiological activity and the concentration of dissolved organic carbon and ammoniacal nitrogen started to increase in the UF permeate. Due to the lower permeate flux, the OMBR had a higher membrane area requirement which represented the main contributor for the total operating costs. [ABSTRACT FROM AUTHOR]

Processes for separating solutes from water, including desalination, are based on synthetic membranes using the forward osmosis (FO) technique. The industrial-level success of these membrane techniques has been astounding. Modern desalination membranes, however, cannot extract a single metal ion with precision from a commingled ion solution. Lithium, cobalt, uranium, and other energy-critical elements will soon be in greater demand than they can meet, thus elevating their importance as geopolitical resources. Critical metals can be found in seawater, an essential yet unconventional supply. Gold mining and ore processing are activities of great economic importance. However, they are related to generating extremely polluted effluents containing high concentrations of heavy metals and low pH. The review highlights the most recent design and deployment of FO desalination technologies, their application in sea mining, and the remaining challenges and prospects. This work also highlights the enormous potential of FO sea mining and how it is crucial to optimize the operating parameters, including draw solutions and energy consumption, and raise attention toward the economic aspect and market diffusion of FO sea mining. [Display omitted] • The advantages of using FO technology in sea mining are highlighted and discussed. • Several investigations, including FO energy consumption, and draw solute choice, are described in depth. • Draw solution characteristics, properties and choice criteria are highlighted and discussed. • Challenges and prospects using FO in sea mining have been proposed. [ABSTRACT FROM AUTHOR]

This study is to evaluate the athermal forward osmosis (FO) concentration process of blueberry juice using food additives as a draw solution (DS). The effects of food additives, including citric acid, sodium benzoate, and potassium sorbate, on the concentration processes are studied, and their effects on the products and membranes are compared. Results show that all these three food additives can be alternative DSs in concentration, among which citric acid shows the best performance. The total anthocyanin content (TAC) of blueberry juice concentrated by citric acid, sodium benzoate, and potassium sorbate were 752.56 ± 29.04, 716.10 ± 30.80, and 735.31 ± 24.92 mg·L−1, respectively, increased by 25.5%, 17.8%, and 19.9%. Meanwhile, the total phenolic content (TPC) increased by 21.0%, 10.6%, and 16.6%, respectively. Citric acid, sodium benzoate, and potassium sorbate all might reverse into the concentrated juice in amounts of 3.083 ± 0.477, 1.497 ± 0.008, and 0.869 ± 0.003 g/kg, respectively. These reversed food additives can make the TPC and TAC in juice steadier during its concentration and storage. Accordingly, food additives can be an excellent choice for DSs in the FO concentration process of juices, not only improving the concentration efficiency but also increasing the stability of blueberry juice.

Biogas slurry poses a severe challenge to the sustainable management of livestock farms. The technology of the forward osmosis (FO) membrane has a good application prospect in the field of biogas slurry concentration. Further research is needed to verify the effects of different draw solutions on FO membranes in biogas slurry treatment and the related membrane fouling characteristics. In this study, three different draw solutions were selected to evaluate the performance of FO membranes for biogas slurry concentration. Membrane fouling was investigated by characterization after FO membrane treatment to identify fouling contaminants. The result showed that FO membrane treatment can realize the concentration of biogas slurry and MgCl2 as the draw solution has the best effect on the concentration of biogas slurry. The different draw solutions all contributed to the efficient retention of most organics and TP while each treatment was ineffective at retaining nitrogen. The cake layer that appeared after the biogas slurry was concentrated covered the surface of the FO membrane. Some functional groups were detected on the surface after membrane fouling, such as C–O and C=C. Moreover, the C element accounts for 57% of the main components of the cake layer after the membrane fouling. Membrane fouling is caused by both organic fouling and inorganic fouling, of which organic fouling is the main reason. This study provides a technical reference for the high-value utilization of biogas slurry.

The remarkable advancement of forward osmosis (FO) as a promising technology for water treatment encounter difficulties due to the synthesis and recovery of a suitable draw solution (DS). The easy recyclability of the draw solution and energy consumption are the critical issues in FO processes. In this work, we have introduced the magnetic core-hydrophilic shell nanoparticles as an efficient draw solute for FO processes. The surface of nanoparticles was modified with sodium alginate sulfate (SAS) as a biocompatible, low toxic and relatively low-cost hydrophilic material. In this regard, the dispersibility and stability of Fe 3 O 4 nanoparticles in aqueous solution was enhanced. The average water flux of 0.06 g mL–1 Fe 3 O 4 @SiO 2 -SAS was determined as 12.8 and 8.5 L m–2 h–1 with a reverse solute flux of 1.48 and 0.23 g m–2 h–1 in PRO and FO modes, respectively. Concentrations of 0.05, 0.1 and 0.2 M NaCl have been used as feed solution to study the performance of the DS for desalination process. Moreover, the optimum DS was successfully used for treatment of a real wastewater. Eventually, the synthesized draw solution was recovered by a magnetic field and its reusability was tested. High stability and simple regeneration of DS decreases the cost of water production. [ABSTRACT FROM AUTHOR]

Certain challenges exist in forward osmosis (FO) separation technique that has to be studied yet such as a selection of a proper draw solution (DS) to supply the required driving force for separation. In this work, the performance of molasses DS in terms of water flux (Jw) was evaluated using a commercial FO membrane. Deionized water (DIW), an oilfield brackish wastewater (BWW) and seawater (SW) were used as three different feed solutions (FS). Effects of molasses concentration (CDS) and solutions cross-flow velocities on Jw were investigated. The results indicated that the relationship between Jw and CDS is non-linear that may be attributed to internal concentration polarization in the membrane support layer. Jw was improved slightly by increasing the FS velocity and enhanced moderately by increasing the DS velocity from 6 to 11.5 cm/s. Fluxes of 16.7, 13.3 and 7.5 LMH were obtained during 30 min against the feeds of DIW, BWW and SW, respectively. After 12 h, the osmotic pressure of molasses is reduced from an initial value of 79.8 bar to 54.5, 62.8 and 66.3 bar for the FSs, respectively. Reverse solute flux is increased by decreasing Jw and is more significant at values lower than 10.67 LMH for DIW feed. Based on the results, Molasses has a good performance ratio in comparison to other fertilizers and diluted molasses can potentially be used for fertigation purposes. [ABSTRACT FROM AUTHOR]

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final freshwater product. Three draw solutions, namely, MgCl 2 , NaCl, and C 3 H 5 NaO 2 , were initially tested against a synthetic water mimicking a pretreated produced water effluent having an osmotic pressure equal to 16.3 bar. MgCl 2 was thus selected for high-recovery experiments. Different combinations of draw solution osmotic pressure (30, 40, 60, 80, and 120) and draw-to-feed initial volume ratios (1, 1.6, and 2.2) were tested at the laboratory scale, achieving recovery rates between roughly 35% and 70% and water fluxes between 4 and 8 L m -2 h -1 . One-dimensional, system-wide simulations deploying the analytical FO water flux equation were utilized to validate the experiments, investigate co-current and counter-current configurations, and understand the system potential. The diluted draw solutions were then transferred to nanofiltration to regenerate their original osmotic pressure. There, the highest observed rejection was 96.6% with an average flux of 21 L m -2 h -1 , when running the system to achieve 100% relative recovery.

The promising forward osmosis (FO) membrane desalination is viewed as a potentially viable energy-efficient performance technology compared to other techniques. But, the core problem in the FO process is the absence of appropriate draw solutes that can be effectively regenerated. Thermoresponsive materials are thus attractive to draw solutes to promote in realizing this target. Among those, thermoresponsive ionic liquids stand out as prominent candidates as their ionic nature generally pledge a high osmotic pressure. The water flux achieved in the FO process indicated there indeed still a need for a better approach in identifying an ideal draw solution. Besides water flux, the attempt to clarify the factor that effect FO performance such as osmotic pressure, operating conditions and membrane selection yet vague. Due to a large number of possible ionic liquids (ILs) combination, there are several prediction methods in screening a potential ILs before synthesis instigated. Finally, the conclusions and important summaries were presented according to the data collected. [ABSTRACT FROM AUTHOR]