Temperature Effect on Forward Osmosis

In order to ensure efficient wastewater treatment and seawater desalination, adequate modeling and optimization of the forward osmosis (FO) process has the potential to be very helpful. This paper deals with the FO model parameters calibration and FO process optimization by a gradient-based optimization method. For this purpose, an upgraded FO model, which involves temperature- and agent-dependent parameters, was developed. The FO model calibration was done using NaCl as agents in draw solution, while MgCl2 was used for model validation. The agreements between simulated and measured FO performance were satisfactory; relative index of agreement are higher than 0.99. By using the proposed FO model, the optimization of FO process conditions was performed with various definitions of the objective and constraint functions. In case of maximizing the water flux, minimizing reverse solute flux, and fulfilling the required constraints, the ratio of water flux and reverse solute flux increased up to 40 % for NaCl and up to 20 % for MgCl2; meanwhile the effective osmotic pressure difference was improved 2-times for NaCl and up to 3.8-times for MgCl2. The optimization process proved to be stable and efficient and can easily be adapted or upgraded for more complex dynamic FO modeling.

Toward a combined system of forward osmosis and reverse osmosis for seawater desalination

Numerical analysis of spacer impacts on forward osmosis membrane process using concentration polarization index

As an essential process in food industry, fruit dewatering should have the least impact on the nutritional values of the product. In this research, bitter orange juice was concentrated via the forward osmosis (FO) process for the first time. For this purpose, cellulose acetate butyrate (CAB)/OH‐functionalized multiwalled carbon nanotubes (FMWCNTs) membranes were prepared using various nanofiller concentrations. The obtained membranes were characterized in terms of their morphology, porosity, water contact angle, chemical structure, tensile properties, and pure water flux. During the FO process, NaCl solution was applied as the draw solution (DS), and the concentration of NaCl was varied (1.2, 2.2, and 4.2 M) to assess its effect on the process performance. Increasing FMWCNTs loading in the casting solution up to 0.3 wt% boosted the membrane porosity, hydrophilicity, elastic modulus, and pure water flux. The CAB membrane incorporated with 0.3 wt% nanofiller and the DS with 4.2 M NaCl concentration represented the highest water flux (29.93 L/m2h) in the FO experiment and provided the maximum turbidity (1545 NTU) and viscosity (4.64 cP) of the treated feed. According to the obtained results, the developed CAB/FMWCNTs membrane proved promising in the FO concentration of fruit juice.Practical ApplicationsBitter orange juice was concentrated via the FO process using the developed CAB/OH‐FMWCNTs membranes. According to the results, water flux, and thus the dewatering efficiency increased and reached its highest value using the CAB membrane incorporated with 0.3% FMWCNTs. Since membrane processes operate at low temperatures and do not deteriorate the concentrate quality, FO concentration of bitter orange juice using the membrane modified in this study can be a superior alternative to the conventional thermal methods.

This paper was aimed to study the efficiency of forward osmosis (FO) process as a new application for the treatment of wastewater from textile effluent and the factors affecting the performance of forward osmosis process.The draw solutions used were magnesium chloride (MgCl2), and aluminum sulphate (Al2 ( SO4)3 .18 H2O), and the feed solutions used were reactive red, and disperse blue dyes.Experimental work were includes operating the forward osmosis process using thin film composite (TFC) membrane as flat sheet for different draw solutions and feed solutions. The operating parameters studied were : draw solutions concentration (10 – 90 g/l), feed solutions concentration (5 – 30 mg/l), draw solutions flow rate (10 – 50 l/hr), feed solutions flow rate (20-60 l/hr), constant pressure and temperature were maintained at 0.5 bar and 30ºC respectively. And includes operating the forward osmosis process using cellulose triacetate (CTA) membrane as flat sheet for different draw solutions and feed solutions. The operating parameters studied were : draw solutions concentration (10 – 90 g/l), and feed solutions concentration (5 – 30 mg/l), constant temperature at 30ºC. It was found that water flux increases with increasing draw solution concentration, and feed solution flow rate and decreases with increasing draw solution flow rate and feed solution concentration for TFC and CTA. It was found MgCl2 given water flux larger than Alum. And also found that reactive red given water flux larger than disperse blue.The experiments also show that CTA membrane gives higher water flux than TFC membrane for forward osmosis operation. The increase in water flux for CTA is about 12.85% than TFC.

Novel forward osmosis process to effectively remove heavy metal ions

6 - Recent developments in forward osmosis and its implication in expanding applications

Concentration of brine by forward osmosis: Performance and influence of membrane structure

ABSTRACTIn this study, we fabricated a nanofibrous composite (NFC) membrane as a substrate to produce forward osmosis (FO) membranes, and we also assessed the use of liquid fertilizer as a draw solution for the FO process in order to produce agricultural irrigation water. Commercial cellulose triacetate (CTA) and thin-film composite (TFC) FO membranes were included in this study. Under FO tests, the NFC, CTA, and TFC membranes achieved initial osmotic water flux values of 35.31, 6.85, and 3.31 L/m2·h and final osmotic water flux values of 12.62, 6.31, and 3.85 L/m2 h, respectively. The reason for the high osmotic water flux of the NFC membrane is because its nanofiber layer has low tortuosity, high porosity, and a low thickness, resulting in a reduction in the internal concentration polarization phenomenon. When liquid fertilizer was used as the draw solution, the water flux values in the FO experiments for the NFC, CTA, and TFC membranes were 15.54, 5.46, and 2.54 L/m2 h. Finally, our results revealed that the FO process using liquid fertilizer as a draw solution can be applied to produce agricultural irrigation water from brackish water and the newly fabricated NFC membrane can be applied to the FO process.

Revised external and internal concentration polarization models to improve flux prediction in forward osmosis process

Predicting the permeate flux is critical for evaluating and optimizing the performance of the forward osmosis (FO) process. However, the solution diffusion models have poor applicability in accessing the FO process. Recently, the data-driven eXtreme Gradient Boosting (XGBoost) algorithm has been proven to be effective in processing structure data in engineering problems and has not been utilized to assess the FO process. Herein, a combination of the XGBoost model with a genetic algorithm (GA) was first proposed to predict the permeate flux, highlighting its superiority in the FO process through comparison of the support vector regression (SVR) model, the artificial neural network (ANN), and the multiple linear regression (MLR). Moreover, the performance of these models was optimized by tuning hyperparameters with a genetic algorithm (GA) and compared via Taylor Diagram. Among these machine learning (ML) models, the GA-based XGBoost model is superior to the other three models in terms of mean square error (MSE, 2.7326) and coefficient of determination (R2, 0.9721) on the test data, and its prediction power was compared to that of the solution diffusion (SD) model in the literature. Finally, further insight into the feature importance that affects the permeate flux in the FO process was examined by utilizing the SHapley Additive exPlanations (SHAP) to estimate the contribution value of various variables. The results demonstrated that the XGBoost model could predict the permeate flux in the FO system with high accuracy and good generalization ability for the given data set and even on the unseen data. Furthermore, the findings of the SHAP method show that the osmotic pressure difference, the osmotic pressure difference of draw solution and FS solution, the crossflow velocity of the feed solution and draw solution, and the water permeability coefficient have a significant impact on water flux.

Membrane compaction in forward osmosis process

Authors demonstrate the crystallisation of lithium carbonate (Li2CO3) microcrystals from brines of salt lakes using a forward osmosis (FO) process. In this FO process, FO is used to enrich the brine of the salt lake, and subsequently, Li2CO3 recovery in the form of microcrystal, while MD is used to recover the draw solution and extract clean water from the brine of the salt lake. The precipitates obtained in the hybrid process were verified to be Li2CO3 microcrystals owing to the lower saturation level compared to the other crystals comprising Li+, Na+, CO32 − , and Cl− in the saline water. An increased thickness of crystallised layer was observed on the anti-scaling FO membrane, which was strongly dependent on the surface energy of the surface, and the microcrystals were collected after a brief, simple membrane flushing using deionised water. By fine modification of the surface in a thin film composite (TFC) membrane with 3-(methacryloylamino)propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide, polyethylene glycol, 2-(2,3,6-trifluorophenoxy)ethanol, the crystallisation rate on the surface was gradually reduced, while the crystal polymorphism was controllable from meta-stable α-form into stable γ-form. Results reported here highlight the potential and high efficiency of the FO process for crystallisation of Li2CO3 from brines of salt lakes.

A review of draw solutes in forward osmosis process and their use in modern applications

Preface