Forward Osmosis Mode Research Articles

A novel corrugated wall channel module for external concentration polarization mitigation in forward osmosis process.

Much work has been conducted on the topic of forward osmosis (FO), but only a few studies have focused on mitigating external concentration polarization (ECP). This study introduced a simple structure, the corrugated wall channel, to the design of FO module, to induce vortex, and then mitigate ECP. In this study, the corrugated wall channel module (CWCM) was tested under given conditions, with a traditional flat membrane module (FMM) as control. CWCM could mitigate ECP and then enhance water flux. When deionized water was taken as feed solution (FS) and 2-M NaCl solution as draw solution (DS), the water flux enhancement was 16.49 and 18.51% in FO mode (active layer facing FS) and PRO mode (active layer facing DS), respectively. When 0.5-M NaCl solution was taken as FS, the corresponding values were 15.92 and 17.13%, respectively. Computational fluid dynamics (CFD) analysis showed that the CWCM could induce vortex, promote the mixing of the solution in the module, and further contribute to the increase of water flux. The specific shape of CWCM affected its performance on mitigating ECP. Also, the more tortuous CWCM exhibited higher water flux. In addition, CWCM could lessen membrane fouling.

Controlling membrane ionization with bifunctional alendronates to benefit desalination through forward osmosis

Gradual ionizing forward osmosis (FO) membranes were synthesized through tailoring modifications with alendronate materials on polyamide thin film composite (TFC) membrane surfaces. The newly developed membranes have gradually ionized surfaces and are more hydrophilic after introducing amino, hydroxyl and phosphate groups derived from the alendronates. Significantly improved performance was achieved with the alendronate-modified membranes relative to the unmodified membrane. With DI water as the feed and 0.5 M MgCl2 as the draw solution, the novel membranes yielded water fluxes 35–60% higher than the nascent one. When MgCl2 (2.0 M) as the draw solution, alendronate tetrasodium (A-4Na) modified membrane had a water permeation rate of 17.3 LMH under FO mode (feed solution faced the membrane active layer) in seawater desalination, a 25% increase compared to that of the pristine membrane and surpasses many other recently-developed FO membranes, remarkably increasing water filtration efficiency.

Effect of fouling on performance of pressure retarded osmosis (PRO) and forward osmosis (FO)

A layered model is developed to describe mass transport through fouled membranes in pressure retarded osmosis (PRO) and forward osmosis (FO) processes. This resistance-in-series model accounts for salt and water transport through the active layer, support layer, external boundary layers, and the cake layer formed by foulants. Closed-form algebraic expressions for the water flux, salt flux, salt concentration profile, and overall transport coefficients are presented for FO membranes in both membrane orientations. Organic fouling experiments using alginate are used to validate the model and observe the effects of feed salinity, cross-flow velocity, and membrane orientation on foulant accumulation rates. Increasing feed salinity and cross flow velocity both lead to a decrease in foulant accumulation in PRO orientation. Under identical operating conditions, foulant accumulation rates are comparable in FO and PRO modes. The model is then evaluated to show how foulant accumulation affects FO system performance in both membrane orientations. The model is also used to elucidate the effect of fouling on power production in PRO: fouling affects the optimal PRO operating pressure, and a 0.5 mm-thick cake layer can reduce power production by 50%. The mathematical expressions developed serve as a simple tool to predict the performance of fouled membranes in both PRO and FO processes.

Highly hydrophilic thin-film composition forward osmosis (FO) membranes functionalized with aniline sulfonate/bisulfonate for desalination

Appropriate membranes are crucial to maximize the potential of forward osmosis (FO) in water treatment. In this study, high-performance and well-constructed thin-film composite (TFC) FO membranes were developed via chemical modifications for FO desalination. The newly developed membranes consist of an aniline sulfonate/bisulfonate functionalized polyamide layer formed by interfacial polymerization on a poly(ether sulfone) (PES) support. Aniline sulfonate/bisulfonates were covalently bonded to the nascent polyamide layer by the acylation reaction between primary amine and acyl chloride groups. The novel membranes have more hydrophilic and smoother surfaces which are important to increase antifouling capability, thus conducing to improved water transfer rates. The 2,5-disulfoaniline disodium salt (DSA-2Na) modified membrane produced water fluxes 71.5% and 52.0% higher than the pristine membrane under the respective PRO (draw solution facing the active layer) and FO (feed solution facing the active layer) modes against DI water. With simulated seawater as the feed and 2.0 M MgCl2 as the draw solution, DSA-2Na modified membrane created a water flux of 16.7 LMH (FO mode), a 36% increase compared to the pristine membrane with a water flux of 12.3 LMH. This is comparable to the best value reported for seawater desalination, indicating the superiority of the aromatic sulfonate/bisulfonate materials functionalized membranes in FO membrane separation.

Antifouling zwitterion embedded forward osmosis thin film composite membrane for highly concentrated oily wastewater treatment

The raising oil consumption in oil and gas industries has exacerbated the disposal of oil waste into various water streams. This phenomenon has called for treatments to prevent threats to the human and environment. With some great advantages such as lower membrane fouling rate, lower energy requirement and higher water recovery rate compared to the conventional pressure-driven membrane processes, forward osmosis (FO) has been recognized as a potential candidate for oily wastewater treatment. In this study, a poly[3-(N-2-methacryloylxyethyl-N,N-dimethyl)-ammonatopropanesulfonate] (PMAPS) incorporated thin film composite (TFC) membrane with excellent anti-fouling properties was fabricated for oily wastewater through forward osmosis process. PMAPS was blended with polyethersulfone (PES) dope solution and cast into PES support layer. Interfacial polymerization (IP) technique was applied to form a thin polyamide (PA) layer atop of the PES support layer. The PMAPS incorporated TFC membranes were characterized for their morphology and surface hydrophilicity. The resultant 1% PMAPS-TFC membrane exhibited high water flux of 15.79 ± 0.3 L/m2.h and oil flux of 12.54 ± 0.8 L/m2.h when tested in FO mode for oil removal from oily wastewater using 1000 ppm emulsified oily solution as feed solution and 2 M NaCl as draw solution. The oil rejection up to 99% was also obtained. Most significantly, PMAPS incorporated TFC membrane outperformed neat TFC membrane with lower fouling propensity for oily waste treatment. When treating 10000 ppm oil emulsion, PMAPS-TFC was able to achieve average flux recovery rate of 97% while neat TFC only able to achieve 70.8% of average flux recovery rate.

Impact of membrane orientation on the energy efficiency of dual stage pressure retarded osmosis

The performance of Dual Stage Pressure Retarded Osmosis (DSPRO) was analyzed using a developed computer model. DSPRO process was evaluated on Pressure Retarded Osmosis (PRO) and Forward Osmosis (FO) operating modes for different sodium chloride (NaCl) draw and feed concentrations. Simulation results revealed that the total power generation in the DSPRO process operating on the PRO mode was 2.5–5 times more than that operating on the FO mode. For DSPRO operating on the PRO mode, the higher power generation was in the case of 2 M NaCl-fresh and 32% the contribution of the second stage to the total power generation in the DSPRO. To the contrast, he total power generated in the DSPRO operating on the FO mode was in the following order 5M-0.6M > 5M-0.7M > 2M-0.01 > 2M-0.6 M. Interestingly, single stage process operating on the FO mode performed better than DSPRO process due to the severe concentration polarization effects. The results also showed that power density of the DSPRO reached a maximum amount at a hydraulic pressure less than the average osmotic pressure gradient, Δπ/2, due to the variation of optimum operating pressure of each stage. Moreover, results showed that the effective specific energy in the PRO process was lower than the maximum specific energy. However, the effective specific energy of the DSPRO was larger than that of the single stage PRO due to the rejuvenation of the salinity gradient, emphasizing the high potential of the DSPRO process for power generation.

Effect of reverse permeation of draw solute on the rejection of ionic nitrogen inorganics in forward osmosis: Comparison, prediction and implications

In this study, the influence of reverse draw solute permeation on the rejection and prediction of NO3− and NH4+ by forward osmosis (FO) were investigated. The rejection of NO3− and NH4+ were experimentally compared between FO mode (active layer facing the feed water) and RO mode (hydraulic pressure applied). Under similar water fluxes, the rejection ratio of NO3− by HTI-ES membrane was much higher during RO than it was during FO, while the opposite was true for HTI-TFC membrane. For both membranes, the rejection of NH4+ was higher during RO than that it was in FO. Rejection was mathematically predicted by using the solution–diffusion model with the permeability obtained from the diffusion cell. The predicted NH4+ rejection for the HTI-TFC membrane matched well with the experimental rejection ratios. However, the model greatly overestimated the rejection ratios of NO3− by HTI-ES membrane and underestimated the rejection of NH4+ by HTI-ES membrane and NO3− by HTI-TFC membrane. The electrostatic equilibrium at the interface and electrostatic gradient across the membrane may differ between RO, FO and diffusion cell mode, which should be considered in future FO models.

A Novel Multi-Charged Draw Solute That Removes Organic Arsenicals from Water in a Hybrid Membrane Process

The potential of forward osmosis for water treatment can only be maximized with suitable draw solutes. Here a three-dimensional, multicharge draw solute of decasodium phytate (Na10-phytate) is designed and synthesized for removing organic arsenicals from water using a hybrid forward osmosis (FO) - membrane distillation (MD) process. Efficient water recovery is achieved using Na10-phytate as a draw solute with a water flux of 20.0 LMH and negligible reverse solute diffusion when 1000 ppm organic arsenicals as the feed and operated under ambient conditions with FO mode. At 50 °C, the novel draw solute increases water flux by more than 30% with water fluxes higher than 26.0 LMH on the FO side, drastically enhancing water recovery efficiency. By combining the FO and MD processes into a single hybrid process, a 100% recovery of Na10-phytate draw solute was achieved. Crucially, organic arsenicals or Na10-phytate draw solutes are both rejected 100% and not detected in the permeate of the hybrid process. The complete rejection of both organic arsenicals and draw solutes using hybrid membrane processes is unprecedented; creating a new application for membrane separations.

Evaluation of an element-scale plate-type forward osmosis: Effect of structural parameters and operational conditions

This is the first study investigating a plate-type forward osmosis (FO) element in two different operating modes: FO and pressure assisted FO (PAFO). A baseline test was conducted to assess the FO process under different structural parameters and operating conditions. For the PAFO, both the naturally occurring pressure and artificially applied hydraulic pressure in at the feed solution (FS) were considered. FO water flux increased with an increase in the temperature (from 20 to 30°C) and the draw solution (DS) concentration (0.4 to 0.7M). In addition, when the flow rate of the FS increased, the water flux increased and the inlet pressure at the FS side also increased. In the PAFO mode, the water flux increased with an increase in the hydraulic pressure, but the water flux decreased with a 1.5bar hydraulic pressure. The increase in the water flux became smaller as the flow rate difference between the FS and DS increased, which is not the same as the FO mode. This may due to that as the flow rate increases, and the hydraulic pressure is further increased, the central portion of the membrane comes into contact with the spacer at the DS side (bowing phenomenon).

Application of volume-retarded osmosis and low-pressure membrane hybrid process for water reclamation

A new concept of volume-retarded osmosis and low-pressure membrane (VRO-LPM) hybrid process was developed and evaluated for the first time in this study. Commercially available forward osmosis (FO) and ultrafiltration (UF) membranes were employed in a VRO-LPM hybrid process to overcome energy limitations of draw solution (DS) regeneration and production of permeate in the FO process. To evaluate its feasibility as a water reclamation process, and to optimize the operational conditions, cross-flow FO and dead-end mode UF processes were individually evaluated. For the FO process, a DS concentration of 0.15 g mL−1 of polysulfonate styrene (PSS) was determined to be optimal, having a high flux with a low reverse salt flux. The UF membrane with a molecular weight cut-off of 1 kDa was chosen for its high PSS rejection in the LPM process. As a single process, UF (LPM) exhibited a higher flux than FO, but this could be controlled by adjusting the effective membrane area of the FO and UF membranes in the VRO-LPM system. The VRO-LPM hybrid process only required a circulation pump for the FO process. This led to a decrease in the specific energy consumption of the VRO-LPM process for potable water production, that was similar to the single FO process. Therefore, the newly developed VRO-LPM hybrid process, with an appropriate DS selection, can be used as an energy efficient water production method, and can outperform conventional water reclamation processes.

Carboxylic polyethersulfone: A novel pH-responsive modifier in support layer of forward osmosis membrane

Carboxylic polyethersulfone (CPES) was synthesized through a facile acetylation reaction followed by an oxidation treatment and used as a modifier in support layer composition of forward osmosis (FO) membrane. The hydrophilic CPES polymer could ameliorate thin film composite (TFC) membrane performance in water permeation. The inferior sponge-like structure of the pristine PES substrate was changed to appropriate long finger-like one, when the CPES modified polymer dope solution was casted in a basic coagulation bath. In such operational condition, attached carboxylic functional groups were almost deprotonated and the electrostatic repulsion forces among them resulted in the formation of a substrate with open pores and less dense morphology. To prove pH-responsive characteristics of the CPES blended membranes, pH of coagulation bath was switched from 3 to 12. By doing so, water flux drastically increased from 14.23 to 28.03 LMH and from 27.80 to 46.17 LMH in FO mode (active layer facing feed water) and PRO mode (active layer facing draw solution), respectively. Further studies showed that such pH treatments could also lower the unfavorable structure parameter (S) from 1423.54 to 653.94µm. The pH-reversibility of the obtained membranes were evaluated using different draw solution pH values. In an acidic draw solution (pH = 3), the protonated carboxylic functional groups started shrinking and thus could open the substrate’s pores, which facilitate rapid water transportation. This investigation may open up a new class of pH-responsive and pH-reversible material for promising FO process, in which permeability and selectivity of a FO membrane could be readily controlled through fluctuation in pH of coagulation bath or draw solution.

Highly permeable and mechanically durable forward osmosis membranes prepared using polyethylene lithium ion battery separators

A porous polyethylene (PE) membrane commercialized as a lithium ion battery separator was utilized as a support for the fabrication of a highly permeable and mechanically durable thin film composite (TFC) forward osmosis (FO) membrane. The highly open and interconnected pore structure of the PE support combined with its thin thickness (~8µm) is beneficial for mitigating internal concentration polarization, thus enhancing FO water flux. The proper plasma treatment on the PE support and the use of a surfactant enabled the stable formation of a polyamide permselective layer on top of the support via a commercial interfacial polymerization process. The prepared PE-supported TFC (PE-TFC) membrane exhibited a remarkably high FO performance (~3.5 times higher water flux and ~35% lower specific salt flux than the commercial HTI-CTA membrane in FO mode) due to its significantly low structural parameter (~161µm) and high permselectivity. The PE-TFC membrane also had superior mechanical properties compare to the much thicker commercial FO membrane due to the exceptionally high mechanical integrity of the PE support, ensuring the mechanically stable membrane operation. The proposed strategy offers a new material platform for FO membranes with strong commercial potential and excellent performance and durability.

A novel TFC forward osmosis (FO) membrane supported by polyimide (PI) microporous nanofiber membrane

A novel interfacial polymerization (IP) procedure on polyimide (PI) microporous nanofiber membrane support with mean pore size 1.27μm was reported. Using m-phenylenediamine (MPD) as aqueous phase monomer, trimesoyl chloride (TMC) as organic phase monomer, ethanol as aqueous phase co-solvent, thin-film composite (TFC) forward osmosis (FO) membrane was fabricated by two IP procedures. The first IP procedure with the unconventional order (ie, the membrane was immersed in the TMC organic phase first, then in the co-solvent ethanol-water MPD aqueous phase) was used to diminish the pore size of PI microporous nanofiber membrane support for the formation of the polyamide layer. The secondary IP procedure was employed to form the relatively dense polyamide layer with conventional order (ie, the membrane was immersed in the co-solvent ethanol-water MPD aqueous phase first, then in the TMC organic phase). The experimental results showed that higher ethanol concentration led to the relatively higher pure water permeability in RO process and osmotic water flux in FO process, whereas NaCl rejection in RO process decreased and reverse salt flux increased. The specific salt flux (Js/Jv) of TFC FO PI nanofiber membrane (PIN-2-4) could be as low as 0.095g/L in FO mode. These results could be attributed to influence of the addition of ethanol into aqueous phase on the surface morphology, hydrophilicity and polyamide layer structure.

Anti-Fouling Double-Skinned Forward Osmosis Membrane with Zwitterionic Brush for Oily Wastewater Treatment

Despite its attractive features for energy saving separation, the performance of forward osmosis (FO) has been restricted by internal concentration polarization and fast fouling propensity that occur in the membrane sublayer. These problems have significantly affected the membrane performance when treating highly contaminated oily wastewater. In this study, a novel double-skinned FO membrane with excellent anti-fouling properties has been developed for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between a highly dense polyamide (PA) layer for salt rejection and a fairly loose dense bottom zwitterionic layer for emulsified oil particle removal. The top dense PA layer was synthesized via interfacial polymerization meanwhile the bottom layer was made up of a zwitterionic polyelectrolyte brush - (poly(3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone), abbreviated as PMAPS layer. The resultant double-skinned membrane exhibited a high water flux of 13.7 ± 0.3 L/m2.h and reverse salt transport of 1.6 ± 0.2 g/m2.h under FO mode using 2 M NaCl as the draw solution and emulsified oily solution as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation.

Forward osmosis for oily wastewater reclamation: Multi-charged oxalic acid complexes as draw solutes

Forward osmosis (FO) has demonstrated its merits in hybrid FO seawater desalination. However, FO may have a potential for other applications if suitable draw solutes are available. In this study, a series of novel draw solutes based on oxalic acid (OA)-transitional metal complexes are presented. Influential factors of FO performance have been systematically investigated by varying the transitional metals, cations of the complex draw solutes as well as the experimental conditions. Compared to NaCl and other recently synthesized draw solutes, the OA complexes show superior FO performance in terms of high water fluxes up to 27.5 and 89.1 LMH under the respective FO and PRO (pressure retarded osmosis) modes, both with negligible reverse solute fluxes. The features of octahedral geometry, abundant hydrophilic groups and ionic species are crucial for the OA complexes as appropriate draw solutes with satisfactory FO performance. Among the synthesized OA complexes, the ammonium salt of chromic complex (NH4-Cr-OA) outperforms others due to the presence of more ionic species in its complex system. NH4-Cr-OA also performs better than the typical NaCl draw solute in FO oily wastewater treatment with higher water recovery and negligible reverse fluxes. Dilute solutions of OA complexes have been reconcentrated through membrane distillation (MD) and reused to new round of FO processes. The OA complexes have demonstrated their suitability and superiority as a novel class of draw solutes for the FO process in this study.

Phenol rejection by cellulose triacetate and thin film composite forward osmosis membranes

Abstract This study aims to elucidate the separation of phenol by reverse osmosis (RO) and forward osmosis (FO) modes and propose strategies to enhance phenol rejection by these two processes. The results show that phenol rejection was strongly influenced by water flux, membrane materials, membrane structure, modes of operation, and feed solution chemistry (i.e. pH). The relationship between phenol rejection and water flux was demonstrated by the irreversible thermodynamic model which could accurately simulate phenol rejection as a function of water flux. At pH 7, phenol rejection by cellulose acetate (CTA) membranes was negligible while the thin film composite (TFC) polyamide (PA) membranes exhibited much higher phenol rejection. Through a systematic static adsorption experiment, results in this study show that phenol adsorption to CTA material was about 20 times higher than that to PA material. Thus, the observed higher phenol rejection by TFC PA compared to CTA membranes was attributed to the significantly higher affinity of phenol toward CTA and the sorption diffusion transport mechanism of phenol through the membrane. In particular, a TFC PA membrane specific for FO operation was prepared in this study. In FO mode, the tailor-made TFC PA membrane showed a slightly higher phenol rejection and a much higher water permeability compared to the commercial membrane. At the same water flux and solution pH, phenol rejection in FO mode was consistently higher than in RO mode. This observation could possibly be attributed to the reverse diffusion of draw solutes in the FO mode which hinders the forward diffusion of phenol through the membrane. A significant increase in phenol rejection was achieved by increasing the feed pH above the dissociation constant of the compound.

Regenerable Polyelectrolyte Membrane for Ultimate Fouling Control in Forward Osmosis.

This study demonstrated the feasibility of using regenerable polyelectrolyte membranes to ultimately control the irreversible membrane fouling in a forward osmosis (FO) process. The regenerable membrane was fabricated by assembling multiple polyethylenimine (PEI) and poly(acrylic acid) (PAA) bilayers on a polydopamine-functionalized polysulfone support. The resulting membrane exhibited higher water flux and lower solute flux in FO mode (with the active layer facing feed solution) than in PRO mode (with the active layer facing draw solution) using trisodium citrate as draw solute, most likely due to the unique swelling behavior of the polyelectrolyte membrane. Membrane regeneration was conducted by first dissembling the existing PEI-PAA bilayers using strong acid and then reassembling fresh PEI-PAA bilayers on the membrane support. It was found that, after the acid treatment, the first covalently bonded PEI layer and some realigned PAA remained on the membrane support, acting as a beneficial barrier that prevented the acid-foulant mixture from penetrating into the porous support during acid treatment. The water and solute flux of the regenerated membrane was very similar to that of the original membrane regardless of alginate fouling, suggesting an ultimate solution to eliminating the irreversible membrane fouling in an FO process. With a procedure similar to the typical membrane cleaning protocol, in situ membrane regeneration is not expected to noticeably increase the membrane operational burden but can satisfactorily avoid the expensive replacement of the entire membrane module after irreversible fouling, thereby hopefully reducing the overall cost of the membrane-based water-treatment system.

Electrolysis-assisted mitigation of reverse solute flux in a three-chamber forward osmosis system

Forward osmosis (FO) has been widely studied for desalination or water recovery from wastewater, and one of its key challenges for practical applications is reverse solute flux (RSF). RSF can cause loss of draw solutes, salinity build-up and undesired contamination at the feed side. In this study, in-situ electrolysis was employed to mitigate RSF in a three-chamber FO system (“e-FO”) with Na2SO4 as a draw solute and deionized (DI) water as a feed. Operation parameters including applied voltage, membrane orientation and initial draw concentrations were systematically investigated to optimize the e-FO performance and reduce RSF. Applying a voltage of 1.5 V achieved a RSF of 6.78 ± 0.55 mmol m−2 h−1 and a specific RSF of 0.138 ± 0.011 g L−1 in the FO mode and with 1 M Na2SO4 as the draw, rendering ∼57% reduction of solute leakage compared to the control without the applied voltage. The reduced RSF should be attributed to constrained ion migration induced by the coactions of electric dragging force (≥1.5 V) and high solute rejection of the FO membrane. Reducing the intensity of the solution recirculation from 60 to 10 mL min−1 significantly reduced specific energy consumption of the e-FO system from 0.693 ± 0.127 to 0.022 ± 0.004 kWh m−3 extracted water or from 1.103 ± 0.059 to 0.044 ± 0.002 kWh kg−1 reduced reversed solute. These results have demonstrated that the electrolysis-assisted RSF mitigation could be an energy-efficient method for controlling RSF towards sustainable FO applications.

Thin-Film Nanocomposite (TFN) Membranes Incorporated with Super-Hydrophilic Metal-Organic Framework (MOF) UiO-66: Toward Enhancement of Water Flux and Salt Rejection.

Zirconiumv (IV)-carboxylate metal-organic framework (MOF) UiO-66 nanoparticles were successfully synthesized and incorporated in the polyamide (PA) selective layer to fabricate novel thin-film nanocomposite (TFN) membranes. Compared to unmodified pure polyamide thin-film composite (TFC) membranes, the incorporation of UiO-66 nanoparticles significantly changes the membrane morphology and chemistry, leading to an improvement of intrinsic separation properties due to the molecular sieving and superhydrophilic nature of UiO-66 particles. The best performing TFN-U2 (0.1 wt % particle loading) membrane not only shows a 52% increase of water permeability but also maintains salt rejection levels (∼95%) similar to the benchmark. The effects of UiO-66 loading on the forward osmosis (FO) performance were also investigated. Incorporation of 0.1 wt % UiO-66 produced a maximum water flux increase of 40% and 25% over the TFC control under PRO and FO modes, when 1 M NaCl was used as the draw solution against deionized water feed. Meanwhile, solute reverse flux was maintained at a relatively low level. In addition, TFN-U2 membrane displayed a relatively linear increase in FO water flux with increasing NaCl concentration up to 2.0 M, suggesting a slightly reduced internal concentration polarization effect. To our best knowledge, the current study is the first to consider implementation of Zr-MOFs (UiO-66) onto TFN-FO membranes.

Modeling and simulation of forward osmosis process using agent-based model system

Abstract In recent years forward osmosis (FO) process has attracted considerable attention in the field of water treatment and desalination. However, the lack of sufficient information on all possible parameters, affecting the process performance, is a major obstacle that avoids improving the function of this method. In this study, an algorithm based upon a reliable model was developed for osmosis through asymmetric membrane oriented in FO mode to be applied in agent-based model. This model was built in the NetLogo platform, which is a programmable modeling environment for simulating natural phenomena. The feasibility of this modeling was proven by comparing the simulation results and empirical data obtained from literature. The influence of net bulk osmotic pressure difference between the draw solution (DS) and the feed solution (FS) on average water flux was studied for various draw solutes. Furthermore, the effects of process parameters, including temperature, length of module, FS cross-flow velocity, pure water permeability coefficient, and structural parameter of membrane on average water flux were investigated. As a result, it could be concluded that Netlogo agent-based model had the quite well potential to simulate the FO process.