Uranium (U) is a chemical and radioactive toxic contaminant affecting many groundwater systems. The focus of this study was to evaluate the suitability of forward osmosis (FO) for uranium rejection ...from contaminated groundwater under field-relevant conditions. Laboratory experiments with aqueous solution containing uranium were performed with FO membrane to understand the uranium rejection mechanism under varied pH, draw solution concentration, and presence of co-ions. Further, experiments were performed with U-contaminated field groundwater. Results of the hydrogeochemcial modelling using PHREEQC indicated that the rejection mechanism of uranium was highly dependent on aqueous speciation. Uranium rejection was maximum at alkaline pH with ca. 99% rejection due to charge-based interactions between membrane and dominant uranyl complexes. The results of the co-ion study indicated that nitrate and phosphate ions decrease uranium rejection. Whereas, bicarbonates, calcium, and magnesium ions concentrated uranium in feed solution. Further, the uranium adsorption onto the membrane surface primarily depended on pH of the aqueous solution with maximum adsorption at pH 5.5. Our results show that the World Health Organization's drinking water guideline value of 30 μgL−1 for U could be achieved via FO process in field groundwater containing low dissolved solids.
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•Uranium mitigation in field relevant (Na+ - HCO3-) low TDS (< 500 mgL−1) groundwater.•Uranium rejection was maximum at alkaline pH (i.e. 99.2% for pH 10.0).•Co-ions viz. nitrate and phosphate reduce uranium rejection.•Bicarbonates, calcium, and magnesium lead to concentrating uranium in feed solution.•WHO's drinking water guidelines were achieved in contaminated groundwater using FO.
Freshwater scarcity is one of the grand challenges that has posed threats to the global economy, societal stability and ecosystem balance. Desalination has been long recognized as an effective ...approach for fresh water production from seawater and brackish water. Forward osmosis (FO) is currently one of the most studied technologies for seawater and brackish water desalination due to its intrinsic advantages compared to reverse osmosis. On the other hand, membrane distillation (MD) is an emerging technology to offer a potentially cost effective thermally-driven desalination process, especially when coupled with waste heat and solar thermal. One major and inevitable challenge for FO and MD is membrane fouling. For decades, fouling and its related topics have gained extensive attention from the desalination communities and various strategies have been implemented to tackle this long standing issue. In this contribution, the fouling mitigation strategies in terms of pretreatment, membrane surface modification and operating conditions for both FO and MD processes are comprehensively reviewed.
•FO and MD are emerging technologies for desalination.•A review focuses on fouling mitigation strategies in FO and MD for desalination.•Membrane modification and operating conditions play important roles in fouling mitigation.
•Fe3+-EDTA-2Na modified membranes offer a promising approach in TrOCs treatment.•Ibuprofen removal rate was significantly increased to up to 98.3%.•More negative charges were formed on membrane by ...complexing with Fe3+.•Active layer with porous structure; complexation layer with various oxygen groups.
Forward osmosis (FO) is a promising technology in the treatment of trace organic substances. However, the development of this technology is limited by membrane material selection and the long-term chemical stability and durability of the membrane. Whereas ibuprofen, a representative trace organic substances that is hydrophobic and negatively charged, poses potential environmental hazards due to its bioactivity. In this work, polyethersulfone (PES) membranes were modified with iron metal complexes via chelation reactions to achieve high rejection rates for ibuprofen. The Fe3+-modified composite FO membrane increased the ibuprofen rejection rate to 98.3 % compared to less than 80.0 % for the original PES membrane. Additionally, the modified membrane enhanced water flux by at least 25.0 % and reduced reverse solute flux to a maximum of 73.0 % of that of the polyamide composite membrane, while significantly improving anti-fouling capabilities. Membrane characterization results revealed that the significant enhancement in the ibuprofen retention rate was due to the addition of a negative charge by forming complexes with Fe3+, which increased intermolecular interactions. Additionally, the dense network structure developed by the Fe3+-EDTA-2Na modification also contributed to the enhanced membrane performance.
In this study, thin-film-nanocomposite forward-osmosis membranes (TFC-FOMs) were assembled with the top polyamide layer being modified by using titanium dioxide (TiO2) nanoparticles with ...camphorsulfonic acid and triethylamine (CT) agents to enhance the separation performance and surface hydrophilicity. The TFC-FOMs were characterized and tested for aquaculture wastewater (AWW) recovery in a bench-scale FO system and a multilayer electro-FO (e-FO) system, respectively. Results show that the CT modified FOM had the highest selectivity, followed by the CT-TiO2 modified FOM. A considerably lower reverse solute flux (RSF) and higher permeate flux were achieved in the separation of the electrolyte from the draw feed or solution under the bipolar membrane (BPM)–BPM modes and anion-exchange-membrane (AEM)–cation-exchange-membrane (CEM). When the CT FOM was used in the e-FO system worked in the AEM–CEM mode under a voltage of 1.5 V, the water production degree reached 711.5 L m−2 in continuous AWW recovery for 6 days, and the energy consumption considerably decreased as the number of membrane sheets was raised from 1 to 4. Overall, the consequences indicated the technical viability of the designed e-FO system for achieving high and stable separation efficiency and low energy consumption in long-duration AWW recovery. Thus, this system shows promise for practical field applications.
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•The CT-modified FOM had the highest selectivity.•A considerably lower RSF and higher permeate flux were achieved in AEM–CEM mode.•The water production rate reached 711.5 L m−2 in the e-FO system during continuous AWW recovery.•The e-FO system operated in the AEM–CEM mode can enhance separation efficiency while maintaining low energy consumption.
Highly permeable membranes can improve the validity of water treatment using forward osmosis (FO) membranes. This study aims to identify the effects of substrate (track-etched (TE) filter) properties ...on the permeability of FO membranes. The polyamide active layer properties of three types of TE filters with similarly-sized pore diameters (0.2 μm) were observed to be equivalent regardless of the substrate porosity (13.7%–15.8 %) and substrate thickness (10–25 μm). Under the same fabrication protocol using 1.5 wt% m-phenylenediamine (MPD) solution with 0.25 wt% sodium dodecyl sulfate (SDS) addition, the increased porosity of the TE filter increased water flux. This suggested that further reduction in thickness and increase in porosity can enhance the water flux. The addition of SDS to an MPD solution was crucial in maximizing the water flux of TE filter-based FO membranes, and the other approaches (no surfactant addition or the addition of Tween80 or hexadecyltrimethylammonium bromide) produced lower water flux. The optimized fabrication protocol presented the highest water flux of 43 L/m2h and reverse salt flux of 10 g/m2h with the draw (1.0 M NaCl) and feed (pure water) solutions. This study determined the best approach for forming a highly permeable PA active layer on TE filters.
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•Thin polyamide FO membranes were fabricated using track-etched (TE) filters.•m-Phenylenediamine solution was laid on the surface using an automatic bar coater.•TE filters with 0.2 μm pore diameters had a 240–270 nm thick polyamide layer.•Sodium dodecyl sulfate (SDS) addition provided the highest water flux.•FO membrane fabricated with 0.2 μm TE filter enabled a water flux of 43 L/m2h.
An NH3/CO2 forward osmosis (FO) membrane brine concentrator (MBC) pilot was tested in the desalination of frac flowback and produced waters from natural gas extraction operations in the Marcellus ...shale region. The average concentration of these waters was 73,000±4200mg/L total dissolved solids (TDS), with an average hardness of 17,000±3000mg/L as CaCO3. Pretreatment included chemical softening, media filtration, activated carbon, and cartridge filtration. Average pilot performance characteristics were: system recovery of 64±2.2%, nominal water flux of 2.6±0.12L/m2-h, concentrated brine concentration of 180,000±19,000mg/L TDS, and product water with 300±115mg/L TDS. The thermal energy required by the FO MBC pilot, when operated within the efficient flow specification of the draw solution recycling system, averaged 275±12kWhth/m3 of product water, approximately 57% less thermal energy input than that estimated for a conventional evaporator operated in a comparable single stage, non-mechanical vapor compression (MVC) configuration. In an MVC configuration, which uses electrical rather than thermal energy, modeling indicates that the FO MBC process will require 42% less electrical energy than a conventional forced circulation MVC evaporator.
► Frac flowback from the Marcellus shale was treated in a NH3/CO2 FO pilot system. ► Average feed TDS was 73,000±4200mg/L, and hardness was 17,000±3000mg/L as CaCO3. ► Product water concentration was 300±115mg/L TDS. ► Energy use was 57% less than that estimated for an open cycle evaporator. ► Commercial system energy use is projected to be 42% less than MVC evaporators.
Emerging technologies present many new possibilities for diversifying the desalination industry, which is currently dominated by thermal desalination, and reverse osmosis. In this review, we ...highlight recent developments in emerging desalination technologies, focusing on those nearing commercialization i.e. forward osmosis and membrane distillation, as well as electrochemical processes that hold potential for technological maturity and upscaling. Literature shows that emerging desalination technologies have benefited greatly from advances in nanomaterials. However, a membrane-based approach alone will not realize commercialization of forward osmosis or membrane distillation. In the case of forward osmosis, appropriate selection of draw solute as well as low-cost recovery of the draw solution towards low energy consumption will be important in full-scale commercialization. In membrane distillation, use of low-grade heat as well as hybrid systems driven by renewable energy sources are likely to facilitate growth. We also review advances in smart process monitoring and control through innovative in situ methods that can further lower operational costs associated with manual sampling and frequent membrane replacement, particularly in membrane distillation. Furthermore, breakthroughs in desalination batteries to remove salt ions using high capacity battery materials may lead to the revival of electrochemical processes for seawater desalination as well as niche desalination applications. Future work should be geared towards optimization of system design and economic assessment of upscaling.
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•Near-commercialization and early stage emerging desalination technologies reviewed.•Membrane distillation is promising for mineral recovery from brine solutions.•Draw solution recovery remains a deterrent to low energy desalination using forward osmosis.•Battery-based desalination linked to revival of electrochemical technologies for brackish water and seawater desalination.•More pilot-scale studies needed to increase technology readiness of emerging processes.
Agriculture consumes approximately 70% of total freshwater worldwide. With limited freshwater resources, alternative water resources are required. This study investigated the performance of a ...fertiliser drawn forward osmosis (FDFO) system for water recovery from synthetic brackish water with repeated use of a cellulose triacetate (CTA) FO membrane under varying fertiliser draw solution (DS) concentrations (0.5, 1 and 2 M KCl); membrane orientations (FO vs PRO) and flow rates (100, 200 and 400 mL/min); with the corresponding effects on the specific energy consumption (SEC). Results demonstrated a robust CTA membrane with no damage. An increased DS concentration from 0.5 to 1 M KCl contributed to a three-fold increase in flux, followed by a 30 to 50% increase for 2 M KCl and a reduced SEC. Membrane orientation and flow rate had insignificant effects on performance, however, flow rate contributed to an SEC increase. FO mode at a lower flow rate combined with a higher DS concentration produced the lowest possible SEC. The study illustrated a potential lower energy process for water recovery from synthetic brackish water whilst at the same time producing a diluted fertiliser that could potentially be used for fertigation.
•Synthetic brackish water recovery produced a diluted fertiliser solution.•Cellulose triacetate membrane with no observed membrane damage after repeated use.•Draw solution concentration increased system performance and decreased SEC.•Membrane orientation did not affect system performance nor SEC.•Flow rate did not affect system performance but had a significant effect on SEC.
This study investigates the effect of surface functionalization of a thin-film composite forward osmosis membrane with zwitterions and silver-based metal organic frameworks (Ag-MOFs) to improve the ...antifouling, anti-biofouling, and antimicrobial activity of the membrane. Two types of zwitterions, namely, 3-bromopropionic acid and 1,3-propane sultone, are chemically bonded, with and without incorporation of Ag-MOFs, over the surface of a polyamide membrane. Spectroscopy measurements indicate successful grafting of the modifying agents on the membrane surface. Contact angle measurements demonstrate a notable improvement in surface wettability upon functionalization. The performance of the membranes is evaluated in terms of water and salt fluxes in forward osmosis filtrations. The transport data show demonstrably increased water flux of around 300% compared to pristine membranes, with similar or slightly reduced salt reverse flux. The antifouling and anti-biofouling properties of the modified membranes are evaluated using sodium alginate and E. coli, respectively. These experiments reveal that functionalized membranes exhibit significant antifouling and anti-biofouling behavior, with high resilience against flux decline.
•Zwitterions and Ag-MOFs are grafted on the surface of FO membranes.•Silver and zwitterions customize the membrane surface properties.•Wettability and surface charge characteristics favorable for antifouling.•Membranes show suitable water fluxes and low reverse salt flux in FO.•Antifouling behaviour against alginate and E. coli is demonstrated.
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•Characterized changes in nanobubble size and concentration over 14 days.•Demonstrated the removal of antibiotics with both ozone and air nanobubbles.•Oxytetracycline was chosen as ...the target pollutant to be removed.•Artificial aquaculture wastewater was used as a complex feed solution.•Nanobubbles enhanced system performance and minimized adsorption of foulants.
The discharge of untreated effluent containing excessive pharmaceutical chemicals (PCs) from aquaculture farms has caused several negative effects on the aquatic ecosystems. Herein, we used a hybrid system based on two emerging technologies, namely forward osmosis (FO) and nanobubbles (NBs), as an energy-efficient, sustainable, and effective alternative to conventional processes for the treatment and reuse of aquaculture wastewater. The combination of NB technology with FO served as a single-step treatment process for the removal of aquaculture pharmaceutical contaminants. In the hybrid system, the FO membrane removed organic matter, dissolved solids, and pharmaceutical chemical residues from aquaculture effluents with a high efficiency (∼98%), whereas NBs functioned as a physical membrane-cleaning agent that enhanced the performance and longevity of the FO membrane. Notably, the results revealed minimal contribution of NBs for the direct degradation of the tested PC i.e. oxytetracycline (OTC), where air and ozone NBs could only oxidize nearly 11% and 30% of the OTC in the water respectively. The relatively higher OTC degradation by ozone NBs was attributed to the ozone NBs-induced reactive hydroxyl radicals (HO•) that react with OTC for its oxidative decomposition. We believe that the tested hybrid system offers a sustainable solution for aquaculture wastewater treatment as well as the recovery of antibiotics from the wastewater and will play a vital role in the sustainable development of the fisheries industry.
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