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Highlights • Comprehensive evaluation of hollow fibre PGMD modules • Effects of hollow fibre packing density, gap channel density and cooling plate material • Energy performance assessment taking membrane surface area into account. • Considerations for hollow fibre PGMD module optimization Abstract In this study, five hollow fibre PGMD modules have been tested to investigate the influence of different module designs on water productivity and energy efficiency in desalination. It is found that modules with low hollow fibre packing density and gap channel density had higher flux and better energy performance in terms of lower Specific Thermal Energy Consumption (STEC). Modules with higher hollow fibre packing density and gap channel density showed higher production of permeate and more efficient use of membrane surface area. It is also found that, the module with a more conductive cooling plate had a higher flux and lower STEC, which was mainly attributed to the lower thermal resistance of the cooling plate. The GOR from this study was in the range of 0.07–0.27, which was relatively low compared to other MD studies. This phenomenon was probably due to the small membrane surface area and insufficient internal heat recovery. Further improvements to this hollow fibre PGMD module have been suggested. [ABSTRACT FROM AUTHOR]

Abstract Comprehensive environmental impact of thermal desalination is poorly understood in Middle Eastern and North African region, especially for multistage flash (MSF) desalination. Nearly 75% of Qatar's municipal water supply is being produced by MSF due to process reliability and other advantages, which is highly energy-intensive and creates an enormous environmental burden. Hence, this paper aimed to develop a multi-faceted, life-cycle based framework that quantifies the overall environmental and human health impacts of MSF desalination in Qatar. Three different MSF systems were examined by varying the gain ratio (GOR) through life cycle assessment. Different environmental loads were examined and evaluated, including climate change, freshwater eutrophication, fossil fuel depletion, ozone depletion, and human toxicity. The results showed that the modified MSF configuration with higher GOR released 7.32 kg CO 2 for 1 m3 of water production while the plant with lowest GOR released 12.6 kg. Quantitative analysis of the environmental degradation caused by desalination reflects the reality of water use in Qatar and can motivate users to reduce their water consumption as part of the Qatar's national vision 2030. The implication of this study is particularly important at a regional level as it serves as a preliminary baseline for a more efficient water strategy. Highlights • 99% of municipal water in Qatar is desalinated seawater. • MSF serves as a mature and reliable technology, producing 75% of all desalted water. • Environmental loads of MSF were identified and evaluated through LCA by varying GOR. • MSF in Qatar has released 4.66 million tons of CO 2 in the year 2014. • Results are intended to provide a baseline for future sustainable water strategy. [ABSTRACT FROM AUTHOR]

Abstract The current study assesses the technical feasibility of using a thermoresponsive polyelectrolyte draw solution (DS) in a Forward Osmosis (FO) desalination pilot scale system of 10 m3/day capacity. The FO system utilized a commercial spiral wound hollow fiber FO membrane and ethylene oxide-propylene oxide copolymer as DS. This study evaluated the effect of DS flow rate and feed solution flow rates on the net water recovery and product water flow rates of the system. The osmotic pressure distribution of polyelectrolyte DS at different sections of the HF module was greatly influenced by DS flow rate. The study revealed that the DS had great potential to generate the high osmotic pressure (Δπ) difference in the various compartments of the HF module. The reliability of the FO pilot plant was proved over a long run without any severe FO membrane fouling with total dissolved solids of product water at 143 ppm and water recovery of 30%. The selected DS showed its potentiality towards the installation of commercial-scale FO desalination plant by witnessing its low viscosity and easy phase separation at a moderately lower temperature of 85 °C in the coalesce DS regeneration system. Graphical abstract Unlabelled Image Highlights • Polyelectrolyte DS having thermo-responsive property was tested in a pilot scale FO system. • Performance of the DS mainly relies on the flow rates of the DS and FS. • High flow rate of DS resulted in overall high-water flux and product flow rate. • Increased FS flow rate increases the rate of dilution of the FS to increase the driving force of the process. • Study recommends further research on development of DS with >45 °C phase transition temperature. [ABSTRACT FROM AUTHOR]

Abstract Membrane distillation (MD) is considered an attractive technology for water desalination processes, but the low transmembrane water fluxes, compared to other desalination processes, is however often pointed out as an important disadvantage. This limitation can be tackled through an effective process engineering analysis. Membrane materials performances and process design (including operating conditions) can both generate increased water flux. These two possibilities are explored in this study, in order to better evaluate the interplay between materials and process role. In a first step, the impact of highly permeable and thin dense selfstanding membranes as an alternative to avoid pore wetting is studied. The use of passive process engineering strategies such as Dean vortices to enhance mass and heat transfer is further analyzed. It is shown that a highly permeable dense membrane material offers a potential twofold increase in water flux, when a permeability of 10−5 kg·m−2·s−1·Pa−1 is achieved. Alternatively, Dean vortices (helical hollow fibers) are of interest only when this level of permeance is obtained; a 20% increase in water flux could be achieved, thanks to a decrease of the temperature polarization effect. Highlights • Two fold water flux increase with thin dense selfstanding membranes • 20% water flux increase with Dean vortices and high performance membranes • No flux increase with Dean vortices and low performance membranes • Interplay between concentration and temperature polarization limits improvements [ABSTRACT FROM AUTHOR]

Abstract Freeze desalination (FD) is a promising desalination technology for overcoming the drawbacks of conventional desalination methods. However, the slow production rate and low productivity of FD have hindered its commercialization. This research presents the challenges confronting current FD processes and proposes a new simplified FD, which employs self-nucleation using the surface scraped freeze crystallizer unit. With the simplified FD process, it was found that optimal conditions are 45 or 50% of the washing water percentage at an operational temperature of −12 °C, and 50% of the washing water percentage at an operational temperature of −16 °C for producing irrigation water (<2000 mg/L in terms of total dissolved solids). Furthermore, we applied the cyclic system, which was the reuse of the mixture of brine and washing waste, on the FD process. The results showed that the use of 45% of the washing water percentage for the 1st cycle raw ice products and 50% for the 2nd cycle at an operational temperature of −12 °C enabled the achievement of >40% in the final productivity. Accordingly, this research introduced the feasibility of the FD process without the use of any additional seeding process. Highlights • Freeze desalination was simplified by applying surface scraped freeze crystallizer. • Surface scraped freeze crystallizer initiated self-nucleation by breaking ice layer. • Freeze desalination conditions for producing irrigation water were optimized. • Cyclic freeze desalination process could enhance ice productivity and purity. • Simplified freeze desalination could produce irrigation water with 40% productivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydrophobic character of PVDF-co-HFP was highly improve by embedded of CNMs/PAC. • Membrane fabrication parameters was statistically optimized using DoE. • Membranes porosity and roughness were highly improved by embedded of CNMs/PAC. • DCMD permeation flux was highly improved up to 102 kg/m2h. Abstract Surface hydrophobicity is the most desirable characteristic for high DCMD performance. Superhydrophobic carbon nanomaterials/powder activated carbon (CNMs/PAC) has unique properties and believed to be the proper candidate to increase the membrane hydrophobicity with maintaining good mechanical properties and high porosity at the same time. In this work, we introduce a phase inversion process based on central composite design, aimed at minimizing the number of experiments required for membrane fabrication. The hydrophobic membrane fabrication conditions are modeled as independent parameters, with the flux provided as the model response. The analyses performed on the membrane structure and surface, as well as its mechanical properties revealed that the superhydrophobic CNMs/PAC significantly enhances the hydrophobicity of the composite membrane surface. The accuracy measurements obtained by analysis of variance showed that the model developed and all the proposed parameters have significant effects on the flux. However, the CNMs/PAC emerged as the most significant influential factor and interacted with polymer concentration and casting knife thickness to exert effects on the permeate flux. The optimum preparation parameters were 775.21 mg carbon loading, PVDF-HFP concentration of 21.86 g and casting knife thickness of 118.93 μm, as these values yield the highest flux of about 102 kg/m2h. [ABSTRACT FROM AUTHOR]

Highlights • GO was synthesized by the Hummers and the modified Hummers methods. • The as-synthesized GO was functionalized with chitosan. • The as-synthesized and the functionalized GO were used as adsorbents. • Salty water desalination using the prepared adsorbents was performed. • GO functionalization with chitosan improves sodium ion adsorption capacity. Abstract In this article, graphene oxide (GO) was synthesized by the Hummers and the modified Hummers methods and functionalized with chitosan and used as adsorbents for salty water desalination application. The results demonstrated that GO prepared via the modified Hummers method has higher adsorption capacity of sodium ions than GO prepared via the Hummers method. Also, functionalization with chitosan improved sodium ions adsorption capacity of the GO prepared via the modified Hummers method from 770.2 to 830.3 mg/g at an initial sodium ion concentration of 40,000 mg/l. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. Regeneration performance of the prepared adsorbents was also studied. The results demonstrated that both isotherms and the pseudo-second-order kinetic model match the obtained experimental data very well. It was found out that the chitosan functionalized GO with higher adsorption capacity and better regeneration performance can be considered as an effective adsorbent for salty water desalination. [ABSTRACT FROM AUTHOR]

Based on one dimensional vertical experiment, considering vertical water injection direction and water injection rate,this study simulated the law of variable density fluid in different directions under continuous water injection condition. On the basis of the experimental simulation, a one-dimensional variable density flow and solute transport mathematical model was established, the vertical isostatic flow law of the variable density fluid was analyzed by numerical simulation and the most effective salt water desalination mode was discussed. The results show that under the same water injection rate, the subsurface saline water body is repaired by water injection in the direction of gravity in the direction of the same water injection rate. In the reverse direction, the test time is short and the total amount of water is small. It is a more effective repair method. With the decrease of water injection rate, the time of repair is greatly increased and the total water consumption is reduced, but the effect of water injection rate is not negligible. [ABSTRACT FROM AUTHOR]

ABSTRACT: The shortage of fresh water is one of the most critical problems our society must address. The most commonly accepted method to produce fresh water is by membrane systems. Since the discovery of aquaporins (AQPs) (water channel proteins), researchers have been trying to incorporate them as functional units in biomimetic membranes to achieve superior water permeability and solute rejection. However, it still remains challenging due to the lack of an effective strategy to stabilize AQPs and fabricate robust membranes. Here, we report the utilization of an amphiphilic peptide (BP1) to stabilize AQPs and use the resulting protein–BP1 complex for desalination purposes. We demonstrated the secondary structure and stability of protein–BP1 complex in aqueous solution using circular dichroism and transmission electron microscopy. The resulting membrane with aquaporin incorporation showed water permeability of 12.33 LMH, improved 28% compared to mutant control membrane, and 83.6% compared to traditional polyamide membrane, while maintaining the high sale rejection (96%). These results demonstrate a great potential of this new incorporating technique for desalination applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46169. [ABSTRACT FROM AUTHOR]

Hollow fiber membranes are more favorable for the fabrication of membrane modules in industry because of its high membrane area to module volume ratios. In the present work, we reported the preparation of novel graphene oxide (GO)/polyimide (PI) hollow fiber membranes for the first time by direct spinning of a GO/PI suspension via a coaxial two-capillary spinning strategy. The structure and morphology of GO/PI hollow fiber membrane was characterized by using XRD, FT-IR and FESEM. The GO nanosheets can homogeneously be dispersed in the PI matrix to form continuous and robust membranes due to a good compatibility between GO and PI, and GO/PI hollow fiber membrane shows a typical asymmetric structure. The performances of the GO/PI hollow fiber membrane were evaluated for desalination of seawater by pervaporation. The GO/PI hollow fiber membrane displays excellent water permeability and salt rejection for desalination of different concentrations of seawater. At 90 °C, a high water flux (15.6 kg m −2 h −1 ) and a high salt rejection (99.8%) can be obtained. Further, the GO/PI hollow fiber membrane displays a high stability for seawater desalination with a long time measurement. [ABSTRACT FROM AUTHOR]

A long-term performance of membrane capacitive deionization (MCDI) was investigated at the presence of organic matter, which has contributed to the understanding of fouling phenomena and energy efficiency. The commercial humic acid and sodium alginate were adopted as model substances representative of natural organic matter, and different ions including sodium and calcium were selected as important parameters considered in both model substances. The experimental results showed reductions in the salinity removal ability and increments of energy usage due to the organic fouling of ion-exchange membranes and carbon electrodes. Within a time interval of approximately 15 d, reductions of NaCl adsorbance with 5.3 and 3.3 mg per cycle were obtained for humics and alginate, respectively. Simultaneously, the energy consumptions increased by 56.9% for humics and 26.3% for alginate. Furthermore, the results in terms of calcium removal in organic feed and energy usage showed that it had a higher fouling potential in comparison to the ones for the sodium solution with equal conductivity and organic concentration. The morphology and composition of the fouling layer were further studied, and it was found that the organic adsorption onto the electrodes and the attachment or even penetration of organic matter on or into the ion-exchange membrane, which could not be efficiently desorbed during the regeneration cycle, were determined as a key problem of demineralized water production. Therefore, this study suggested the necessity of a pre-treatment to reduce the presence of organic matter for the sustainable operation of MCDI, hereby broaden the potential application fields. [ABSTRACT FROM AUTHOR]

The conventional desalination processes are not only energy intensive but also environment un-friendly. They are operating far from thermodynamic limit, 10–12%, making them un-sustainable for future water supplies. An innovative desalination processes are required to meet future sustainable desalination goal and COP21 goal. In this paper, we proposed a multi-effect desalination system operated with ocean thermocline energy, thermal energy harnessed from seawater temperature gradient. It can exploit low temperature differential between surface hot water temperature and deep-sea cold-water temperature to produce fresh water. Detailed theoretical model was developed and simulation was conducted in FORTRAN using international mathematical and statistical library (IMSL). We presented four different cases with deep-sea cold water temperature varies from 5 to 13 °C and MED stages varies from 3 to 6. It shows that the proposed cycle can achieve highest level of universal performance ratio, UPR = 158, achieving about 18.8% of the ideal limit. With the major energy input emanated from the renewable solar, the proposed cycle is truly a “green desalination” method of low global warming potential (GWP), best suited for tropical coastal shores having bathymetry depths up to 300 m or more. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) offers an affordable technology for the reduction of salt concentrations in brackish water. However, there are still drawbacks concerning electrode capacity and energy consumption, compared to other well-established technologies such as reverse osmosis or electrodialysis. This study investigates high-adsorption electrodes based on polyaniline-activated carbon, applying different configurations (symmetric and asymmetric electrodes, and membrane CDI) to optimize electrosorption capacity and energy consumption. A new approach called OSR (optimized salt removal) is proposed, based on simultaneous analysis of the electrosorption capacity and the adsorption/desorption kinetics. This technique was used to evaluate different electrode configurations. The best performance was obtained using MCDI, which improved the electrode capacity from 14.9 to 20.0 mg g −1 , while reducing the specific energy consumption by 21%. It was demonstrated that the performance of the electrode depended on both the specific adsorption capacity ( SAC ) and the electrosorption/desorption kinetics. Fitting the electrosorption and desorption curves using a pseudo-first order kinetic model and applying the OSR method showed that the best desalination was achieved using MCDI at 1.2 V. This configuration did not present the highest SAC or the fastest electrosorption/desorption kinetics, but a good balance was obtained between these two variables. [ABSTRACT FROM AUTHOR]

Desalinated domestic wastewater is an indispensable water resource in arid regions; however, its recovery can be limited by calcium phosphate scaling and fouling of the membrane. Here we investigated calcium phosphate mineralization on oligoamide surfaces that mimics reverse osmosis (RO) and nanofiltration (NF) membrane surfaces. We used a solution that simulates desalination of secondary treated domestic wastewater effluents for calcium phosphate mineralization experiments with oligoamide-coated gold surfaces. Attenuated total reflection–Fourier transform infrared spectroscopy and energy dispersive spectrometry showed that calcium phosphate and carbonate precipitated on RO mimetic surfaces. The rate of precipitation on oligoamide sensors was monitored by a quartz crystal microbalance, showing that scaling was more intense on the RO than the NF mimetic surface and that excessive carboxyl functional groups on both surfaces promoted scaling. Filtration experiments of similar solutions with commercial membranes showed that scaling was more intense on the RO membranes than on the NF membranes, which supported the results obtained with the oligoamide model surfaces. The results of this study can be implemented in developing RO and NF membranes to prevent calcium phosphate scaling and consequently lower water-treatment costs of domestic wastewater treatment. [ABSTRACT FROM AUTHOR]

A FRESH LOOK AT ZERO LIQUID DISCHARGE TECHNOLOGY ILLUSTRATES THE POTENTIAL FOR AFFORDABLE USE AT DESALINATION PLANTS ACROSS THE COUNTRY IN THE FORTHCOMING AWWA MANUAL OF PRACTICE M69. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate the potential of an osmotic membrane bioreactor (OMBR)-membrane distillation (MD) hybrid system for simultaneous wastewater reuse and seawater desalination. A stable OMBR water flux of approximately 6 L m-2 h-1 was achieved when using MD to regenerate the seawater draw solution. Water production by the MD process was higher than that from OMBR to desalinate additional seawater and thus account for draw solute loss due to the reverse salt flux. Amplicon sequencing on the Miseq Illumina platform evidenced bacterial acclimatization to salinity build-up in the bioreactor, though there was a reduction in the bacterial community diversity. In particular, 18 halophilic and halotolerant bacterial genera were identified with notable abundance in the bioreactor. Thus, the effective biological treatment was maintained during OMBR-MD operation. By coupling biological treatment and two high rejection membrane processes, the OMBR-MD hybrid system could effectively remove (>90%) all 30 trace organic contaminants of significant concern investigated here and produce high quality water. Nevertheless, further study is necessary to address MD membrane fouling due to the accumulation of organic matter, particularly protein- and humic-like substances, in seawater draw solution. [ABSTRACT FROM AUTHOR]

While the sustainability of resource depletion is a longstanding environmental concern, wider attention has recently been given to growing water scarcity and groundwater depletion. This study seeks to test the substitutability assumption embedded in weak sustainability indicators using a case study of Californian water supply. The volume of groundwater depletion is used as a proxy for unsustainable water consumption, and defined by synthesising existing research estimates into low, medium and high depletion baselines. These are compared against projected water supply increases from ocean desalination and water recycling by 2035, to determine whether new, drought-proof water sources can substitute for currently unsustainable groundwater consumption. Results show that the maximum projected supply of new water, 2.47 million acre-feet per year (MAF/yr), is sufficient to meet low depletion estimates of 2.02 MAF/yr, but fails to come near the high depletion estimate of 3.44 MAF/yr. This does not necessarily indicate physical limitations of substitutability, but more so socio-economic limitations influenced by high comparative costs. By including capacities in demand-substitutability via urban water conservation, maximum predicted capacities reach 5.57 MAF/yr, indicating wide room for substitution. Based on these results, investment in social and institutional capital is an important factor to enhance demand-side substitutability of water and other natural resources, which has been somewhat neglected by the literature on the substitutability of natural resources. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) membranes incorporated with inorganic nanoparticles into the polyamide layer have recently gained great research interests. However, the incompatibility of introduced nanoparticles and their instability in the TFC membranes are the main challenges. It has been questioned that how the hybridized nanoparticles could sustainably enhance the overall desalination performance within the complex filtration mechanisms in terms of water permeability and salt rejection, as well as mechanical strength of the membranes. Herein, hydrophilic polyethylenimine (PEI) modified silica nanoparticles (SN), noted as SN-PEI, are synthesized with the aim to fabricate SN-PEI hybridized thin film nanocomposite (TFN) membranes for desalination. The successful incorporation of SN-PEI into the TFC membranes is confirmed through characterization techniques. The functional SN-PEI showed promising chemical characteristics to enhance interfacial molecular interactions between the SN and polymer matrix which improve the compatibility of SN with the polymer structure and the mechanical properties of the TFN membranes. Higher hydrophilicity of the TFN membranes due to the SN-PEI incorporation is beneficial for enhancing water molecular transfer through the membrane. Our experimental and statistic data revealed that the SN-PEI hybridized TFN membranes demonstrated up to 46% improvement in water flux, higher salt rejection, and improved mechanical strength compared to the control TFC membranes. Higher hydrophilicity of the TFN membranes due to the SN incorporation is beneficial for enhancing water molecular transfer and antifouling resistance for cost reduced desalination. [ABSTRACT FROM AUTHOR]

In Multi-Effect Distillation with Thermal Vapor Compression (MED-TVC) plants, fixed steam ejectors are usually designed for constant motive steam pressures. When these distillation units are integrated into Concentrating Solar Power (CSP) plants, the available motive steam pressure is normally lower than the design value (due to the partial load operation of the power cycle under different solar radiation conditions), being the efficiency of the steam ejectors drastically reduced. Also, it has a negative impact on the fresh water production from the desalination plant because of a decrease in the mass flow of the motive steam. All this can be avoided by using variable nozzle steam ejectors, which can adjust the mass flow rate of steam according to the variable pressure so that they are always operating with the maximum efficiency and therefore they can maintain the freshwater production of the desalination plant near to the nominal value. This work presents a study of the coupling between CSP plants and MED-TVC units using variable nozzle steam ejectors in a wide range of operating conditions (on and off-design). For this purpose, simulations of a Rankine cycle power block in a typical commercial CSP plant have been firstly performed at different thermal loads to investigate the operational limits that allow keeping the motive steam mass flow rates constant. Then, the efficiency and fresh water production of an MED-TVC unit coupled to the different extractions available at the CSP plant have been studied in a wide range of operating conditions, covering both nominal and partial loads. To this end, an operational model of the MED-TVC unit has been developed based on a design model previously published by the authors. [ABSTRACT FROM AUTHOR]

Aluminium-based metal–organic framework MIL-100 was utilized for the capture of actinide ([UO2]2+, Th4+) and lanthanide (Nd3+) cations. The results indicate a very quick sorption process, leading to very high cation uptakes together with selectivity for Th4+. [ABSTRACT FROM AUTHOR]

A novel diacyl chloride monomer dimethyl (3,5-bis(chlorocarbonyl)phenyl)phosphonate (compound(I)) with a phosphonate group (–PO(OCH 3 ) 2 ) was successfully synthesized and then blended with 2,2′,4,4′-biphenyl tetraacyl chloride (BTEC) as organic phase monomers to prepare RO membranes for brackish water desalination. BM-X was utilized to represent RO membranes prepared by compound (I). X represented the concentration percent of compound (I) (%) in Isopar G solutions，which was the ratio of the concentration of compound (I) to the concentrations of compound (I) and BTEC. When X increased from 0% to 50%, the water flux of BM-X improved from 35 L/m 2 h to 79 L/m 2 h while holding high salt rejections (99.1–99.5%). The enhancement of membrane hydrophilicity was certified by the contact angle decreasing from 83° to 38° with compound (I) content increasing from 0% to 50%. Because the improvement of membrane hydrophilicity made for the enhancement of membrane antifouling, BM-50 exhibited a lower water flux decline and irreversible fouling degree compared with a commercial RO membrane (BW30FR, Dow Filmtec). The irreversible fouling degree reached 6.8% after 1500 min three cycles fouling which was lower than 14.1% of BW30FR. Finally, BM-50 showed a very good and stable desalination performance for 30 days measured in a pH=6.0 and 2000 ppm NaCl solution. [ABSTRACT FROM AUTHOR]

Achieving a high rate of ionic transport through porous membranes and ionic channels is important in numerous applications ranging from energy storage to water desalination, but it still remains a challenge. Herein we show that ions can quickly pass through interlayer spaces in hydrated boron nitride (BN) membranes. Measurements of surfacecharge governed ionic currents between BN nanosheets in a variety of salt solutions (KC1, NaCl and CaCl2) at low salt concentrations (<10-4 M) showed several orders of magnitude higher ionic conductivity compared to that of the bulk solution. Moreover, due to the outstanding chemical and thermal stability of BN, the ionic conduits remain fully functional at temperatures up to 90 °C. The BN conduits can operate in acidic and basic environments and do not degrade after immersing in solutions with extreme pH (pH ~ 0 or 14) for 1 week. Those excellent properties make the BN ionic conduits attractive for applications in nanofluidic devices and membrane separation. [ABSTRACT FROM AUTHOR]

Membrane distillation water desalination can attain a significantly higher water recovery than reverse osmosis, while the lack of stable hydrophobic membranes limits its commercial applications. This article presents the preparation of a new hydrophobic membrane by modifying a porous Si3N4 substrate with vesicular SiNCO nano-particles. The membrane had a water contact angle of 142°, due to the presence of -Si-CH3 terminal groups and the high surface roughness. The contact angle remained nearly the same after exposures of the membrane to boiling water, aqueous solutions with pH ranging from 2 to 12, and benzene. The membrane exhibited satisfactory water desalination performance on highly concentrated NaCl solutions and simulated seawater. With the highly stable membrane, it is promising to develop a zero-discharge water desalination process for simultaneous production of fresh water for daily uses and brine for industrial uses. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1272-1277, 2017 [ABSTRACT FROM AUTHOR]

A hydrophilic, hydrostable porous metal organic framework (MOF) material-MIL-101 (Cr) was successfully doped into the dense selective polyamide (PA) layer on the polysulfone (PS) ultrafiltration (UF) support to prepare a new thin film nanocomposite (TFN) membrane for water desalination. The TFN-MIL-101 (Cr) membranes were characterized by SEM, AFM, XPS, wettability measurement and reverse osmosis (RO) test. The porous structures of MIL-101 (Cr) can establish direct water channels in the dense selective PA layer for water molecules to transport through quickly, leading to the increasing water permeance of membranes. With good compatibility between MIL-101 (Cr) nanoparticles and the PA layer, the lab made TFN-MIL-101 (Cr) membranes integrated tightly and showed a high NaCl salt rejection. MIL-101 (Cr) nanoparticles increased water permeance to 2.2 L/m2·h·bar at 0.05 w/v % concentration, 44% higher than the undoped PA membranes; meanwhile, the NaCl rejection remained higher than 99%. This study experimentally verified the potential use of MIL-101 (Cr) in advanced TFN RO membranes, which can be used in the diversified water purification field. [ABSTRACT FROM AUTHOR]

The main objective of this article is to present a new and practical correlation associating the effectiveness (ε) with its number of transfer unit (NTU) and vice versa of the humidification process. This correlation is featured by its simplicity in use and has non-iterative procedure to implement as the traditional published correlations in the literature. The new correlation can predict the thermal performance/design of the humidifier at different Lewis numbers (both unit and non-unit) with a reasonable accuracy. General integral equation, which is similar to that of Merkel equation, is developed and used in the present humidifier simulation model. The validity of the new correlations was tested against the available experimental and numerical data reported in literature for an industrial air humidifier. In addition, the comparison was conducted with the traditional numerical model at different Lewis numbers. The simulated results of the present correlation show a good agreement with those obtained from the experimental work within 10% accuracy. The main benefits of this new correlation are: (1) its simplicity to be implemented through simple calculations of input parameters and (2) it provides helpful guidelines for developing of humidification-dehumidification HDH desalination cycle simulation program. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) is a non-isothermal membrane separation process capable of operating at low temperature and low transmembrane hydrostatic pressure. Air gap membrane distillation (AGMD) is one of the MD configurations. In this study, the performance of double-stage AGMD unit at different AGMD-operating parameters such as feed temperature, feed flow rate, coolant temperature, coolant flow rate and air gap width is presented. Experimental results revealed that the built double-stage AGMD unit is capable of achieving a maximum cumulative distillate production of 128.46 kg/m2h, a total (average) flux of 64.23 kg/m2h and a single-stage flux of 65.81 kg/m2h. One key feature of the proposed design is the ability of the unit to use a common cooling chamber to provide the necessary cooling required by the two feed chambers. This reduces the total capital, maintenance and total energy consumption costs. Other benefits include simple module design, easy modules installation and improved system productivity. Furthermore, the system can be operated either as a single-stage or double-stage unit. A simple theoretical model for predicting flux in single-stage AGMD unit was equally presented. The model predicted fluxes with less than 13% discrepancy. [ABSTRACT FROM PUBLISHER]

In contrast with the conventional SWRO and BWRO plug flow desalination (PFD) techniques where recovery depends on the number of lined membrane elements and energy consumption on the efficiency of energy recovery device (ERD), the newly conceived closed-circuit desalination (CCD) technologies enable the attainment of high recovery, irrespective of the number of elements per module with low energy consumption without need for ERD. The present theoretical model analysis describes the extreme performance prospects of CCD illustrated by a single-element SWRO–CCD unit performing up to 60% recovery with near absolute energy efficiency without need for ERD (e.g. 50% recovery; 13 lmh; 1.573 kWh/m3for 32,000 ppm NaCl feed equivalent to ocean seawater of 35,000 ppm) as well as by a single-element BWRO–CCD unit performing up to 92% recovery with low energy (e.g. 90% recovery; 25 lmh; 0.472 kWh/m3for 1,500 ppm NaCl feed equivalent to common brackish water sources of 1,700–2,000 ppm). Another illustration pertains to the performance of a single-element BWRO–CCD–PFD unit, wherein replacement of brine by fresh feed takes place at the end of each CCD sequence by a brief PFD step with results showing only a minor increase in energy consumption compared with that of BWRO–CCD (e.g. 90% recovery; 25 lmh; 0.488 kWh/m3for 1,500 ppm NaCl feed). The illustrated theoretical model’s results show good agreement with experimental data and manifest the conceptual differences between CCD and conventional RO techniques at their extreme. [ABSTRACT FROM PUBLISHER]

The performance of desalination and sewage treatment plants operated by contractors at sites of a large company in Oman was evaluated in relation to benchmark costs. Such benchmark costs, which are dependent on plant size and process used, were established based on estimates provided in research literature and based on site-specific estimates made using software models. Desalination economic evaluation program software was used to estimate site-specific costs of desalination and financing for environmental, affordable, and strategic investments that bring on large scale expenditure software was used to estimate site-specific costs of sewage treatment. The estimated site-specific benchmark cost of desalination was 1.20 US$/m3. The desalination cost subject to many variables reported in the literature ranges between 0.52 and 1.30 US$/m3. The estimated site-specific benchmark operational cost of sewage treatment up to the BOD level of 10–15 mg/L of treated water was 0.29 US$/m3. The cost of sewage water treatment, up to the BOD level of 10–15 mg/L of treated water, averages to 0.41 US$/m3based on studies conducted. The evaluation of costs reveals that the cost of desalination and sewage treatment at the company sites was close to benchmark costs provided in the research literature as well as site-specific estimates made using software models. [ABSTRACT FROM PUBLISHER]

This study evaluated possible application of a seawater dilution process (SDP) to a seawater reverse osmosis (SWRO) filtration system for low-energy desalination. The main experiments of this study are to find the effects of the SDP in an SWRO filtration process to reduce seawater salinity. The measured total dissolved solids values were 29,640 mg/L for seawater, 8,720 mg/L for brackish water, and 2,896 mg/L for treated sewage water. In the experiment, two multiple water were blended with seawater to lower salinity. First experiment was conducted seawater with brackish water and found an increase in the permeate flux at 9.6% in the SWRO process. Second experiment was conducted seawater with treated sewage water and delivered an increase in the permeate flux at 12.9%. During the ultrafiltration (UF) operation, the pressure applied in diluted water increased rapidly comparing to seawater because the high concentrations of particulate and organic matter were detected in pretreatment of UF and main treatment of SWRO due to high silt density index and total organic carbon value in supplemental water. Therefore, to optimize application of the SDP, fouling effects should be considered for a longtime operation in membrane processes. [ABSTRACT FROM PUBLISHER]

Asteraceae is one of the largest plant families with many important garden ornamental species. Salt tolerance of 10 aster perennials was evaluated in a greenhouse experiment, including the following: damianita (Chrysactinia mexicana), gregg's mistflower (Eupatorium greggii), shasta daisy (Leucanthemum ×superbum 'Becky'), blackfoot daisy (Melampodium leucanthum), lavender cotton (Santolina chamaecyparissus), aromatic aster (Symphyotrichum oblongifolium), copper canyon daisy (Tagetes lemmonii), four-nerve daisy (Tetraneuris scaposa), skeleton-leaf goldeneye (Viguiera stenoloba), and zexmenia (Wedelia texana). Plants were irrigated with nutrient solution at electrical conductivity (EC) of 1.2 dS·m-1 (control) or saline solutions at EC of 5.0 or 10.0 dS·m-1 (EC 5 or EC 10) for 5 weeks. Upon termination, growth parameters, foliar salt damage, relative chlorophyll content [Soil-Plant Analysis Development (SPAD) readings], and mineral concentration were measured. Gregg's mistflower, skeleton-leaf goldeneye, and lavender cotton were the most salt-tolerant species with less reductions in shoot dry weight (DW) in both EC 5 and EC 10. Considering the relatively severe foliar salt damage (visual quality score of 3.1 and 2.7 at EC 5; 2.4 and 1.6 at EC 10) and mortality rate (10% and 40%) in EC 10, aromatic aster and zexmenia should be avoided where poor quality water may be used for irrigation. Gregg's mistflower and skeleton-leaf goldeneye had relatively lower leaf sodium (Na) concentrations suggesting that both species can selectively exclude Na. Damianita and the four daisies, i.e., blackfoot daisy, copper canyon daisy, four-nerve daisy, and shasta daisy, were salt sensitive as evidenced by their greater growth reduction, foliar salt damage, and high Na and chlorine (Cl) accumulation in leaves, and should be avoided in landscapes where poor quality water may be used for irrigation. [ABSTRACT FROM AUTHOR]

The implementation of seawater desalination, a key strategy to secure fresh water supply in arid and coastal regions, is greatly thwarted by its high cost relating to high energy and equipment cost associated with pressure and the high system or membrane fouling associated with the bi-valence ions in the sea water. Nanofiltration (NF), a lower pressure membrane process with high rejection for divalent ions, had been identified as a key component to reduce the costs relating to both pressure and fouling in the desalination process. Lower cost seawater desalination processes had been developed by integrating NF with various types of desalination technologies including reverse osmosis (RO), forward osmosis (FO), electrodialysis (ED), multistage flash (MSF), multieffect distillation (MED), membrane distillation (MD) and ion exchange (IX). In this paper, after comparing the performance of currently available NF membranes, we attempt to review the recent progresses made in the development of lower cost seawater desalination processes using NF technologies and provide future perspectives for NF technologies. [ABSTRACT FROM AUTHOR]

Over several decades, Hong Kong has implemented a number of technological innovations for securing its water supply. But as population growth and the effects of climate change put pressure on existing water sources, new innovations combined with social adaptations will be required. This commentary offers three suggestions for moving toward urban water sustainability in Hong Kong. The suggestions are: diversify sources of water while minimising dependence on desalination, foster public engagement with water and implement water‐sensitive urban design. These suggestions are not intended to be a panacea but to augment existing measures that when combined can move toward the attainment of urban water sustainability. [ABSTRACT FROM AUTHOR]

Water, is an endless requirement of the living thing all around the universe. But now it is reaching a level of scarcity in all regions which had rich water sources before. This not achieved naturally but we humans in order to find solutions on living with luxury lead a test with environment by destroying the forest, over utilization of ground water sources, improving the level of chemicals in the available ground water with use of chemical fertilizers and with several forms of destructive techniques. Thus we humans who started this should find a solution to end up the arising situation. Which not only have brought solution to the available problems but also acts as a solution for the problems which are going to arise further. [ABSTRACT FROM AUTHOR]

The use of renewable energy in desalination is the only sustainable way to decrease the water deficit without aggravating the energy crisis. Solar desalination is usually presented as the most optimal solution for sustainable desalination since the water needs are usually larger in places with high solar radiation. Considering the potential use of desalination as means of producing water in small isolated communities, the focus of this study lies on the use of solar energy in thermal desalination systems of small–medium capacity and low maintenance requirements. Based on typical values for the thermal energy requirements of such systems and on characteristic performance parameters of commercially available low-temperature solar thermal technologies, different system layouts are assessed and optimal system dimensioning is studied, for different locations, in terms of estimated water production costs. [ABSTRACT FROM PUBLISHER]

Most marine algal species are beneficial, not harmful, as algae are the foundation of the food chain and provide the bulk of Earth’s oxygen through photosynthesis. Mankind also commercially harvests algae for a myriad of uses in the food, pharmaceutical and medical industries to name but a few. However, the sudden prolific growth in algal cell numbers, referred to as harmful algal blooms (HAB), can constitute an operational and/or health risk to desalination plants, threatening water supply security and safety, respectively. The excessive biomass and organics associated with HAB can lead to the closure of desalination plants, particularly sea-water reverse osmosis (SWRO) plants due to overloading of the pretreatment facilities or potential irreversible RO membrane fouling. While these impacts are well documented, the removal of potent marine algal toxins, which represent a potential public health risk if not removed by desalination plant processes, is not well researched. The incidence of HAB has escalated throughout the world with algal specialists reporting that “compared to 30 years ago, we have more algal toxins, more toxic algal species and more areas affected”. Therefore, this paper examines the major marine algal toxins that may be present at the intake of a desalination plant, their fate in thermal and SWRO desalination plant processes and the potential residual risk to public health in desalinated drinking water. Toxin removal in the various process steps is predicted based on the physico-chemical properties of these marine toxins. Results from bench and pilot studies investigating the efficacy of barriers in the desalination technology processes to remove cell-bound toxins and extracellular toxins from ruptured algal cells are also reviewed. [ABSTRACT FROM PUBLISHER]

The use of solar energy to feed the MD desalination process is being evaluated at Plataforma Solar de Almería, the largest European facility for solar energy research, located in SE Spain. A test bed for the evaluation of membrane distillation modules is under operation coupled to a field of static solar collectors. Different commercial modules and real-scale prototypes are tested in continuous operation and coupled with a solar thermal source, in order to obtain data in conditions closer to real applications than the tests performed at laboratory scale. This particular study shows an evaluation of two different modules using spiral-wound membranes, one with a liquid-gap configuration (built by Solar Spring) and the other with an air-gap configuration (built by Aquastill). An assessment of the influence of the operational parameters in the performance was done within the allowed ranges of operation of each prototype, with special attention to the temperatures and the feed flow rate. Also, the influence of the salinity was investigated using feed water with salts at different values of conductivity. The characterization of the systems is done based on the quality of the distillate, as well as the measured values of distillate production and thermal performance, choosing the specific distillate flux obtained and the gain output ratio (GOR) as performance indicators. The main results of the analysis are summarized and compared, discussing the particular operational experiences in each case. [ABSTRACT FROM PUBLISHER]

The main objective of this study is to understand the operation mechanisms of reverse osmosis (RO) membrane and optimization of the operating mechanisms of the RO system in order to reduce the membrane fouling and/or energy requirements. Typically, the high-pressure RO membrane vessel is loaded with membrane elements having the same flux and salt rejection rate. It has been conceived that when different types of RO elements are loaded into the pressure vessel in a special arrangement according to their permeability and salt rejection rate, this arrangement has the potential for reducing the energy consumption of the RO plant. Here, a conceptual design is introduced to describe this new idea. The effects of feed salinity and temperature were investigated in this paper using the reverse osmosis system analysis filmtec membrane design software. A two pass membrane treatment process was designed for desalting seawater at different salinities varied from 35,000 ppm to 43,000 ppm. The results showed a net energy saving from 2.5 to 3% (depends on the feed salinity) could be achieved. The effect of the feed temperature was also investigated, and the new design was found to be more energy efficient. Membrane scaling was also investigated in this study, and it was found that the new membrane arrangement design was less efficient than old design at feed salinity 35,000 ppm and vice versa at feed salinity 45,000 ppm. This was attributed to the use of high membranes permeabilities in the new design. [ABSTRACT FROM PUBLISHER]

Optimal voltage application rate, linear velocity, and mean ion residence time (MIRTd) in dilute stream were searched for electrodialysis reversal desalination by using two different feed waters containing TDS 3330 and 7190 mg/L NaCl. Two sets of literature data were used in the analyses. First, the relation among demineralization degree, voltage application rate, and MIRTdwere derived from theory. Then, the findings were analyzed from the first set of literature data and validated with the second set of data. The analyses show that the maximal demineralization degree does not appear at the highest voltage application alone and that demineralization degree increases with the increasing voltage application rate to a certain critical value only. The maximal demineralization degree occurs at the combination of lower voltage application and longer MIRTdor vice versa. Data show the maximal demineralization degree does not always present the maximal ion removal rate per effective area of cell pairs per power. Therefore, both the maximal demineralization degree and maximal ion removal rate per effective area of cell pair per power were used to gauge optimal voltage application, linear velocity, and MIRTd. Optimal voltage application, linear velocity, and MIRTdwere found to be 45–70 V, 15.1–12.3 cm/s, and 2.3–2.7 min for feed water 3330–7190 mg/L NaCl in Aquamite I membrane stack with Mark I spacer in 135 different operational conditions. [ABSTRACT FROM PUBLISHER]

Effects resulting from the use of reclaimed waters on mandarins and grapefruits are evaluated by measuring the spectral responses of their canopies and the anatomy and the chlorophyll content of their leaves against control trees irrigated with waters provided by an interbasin transfer. Spectral responses from the red (R) and near-infrared (NIR) wavelength bands, and its normalized ratio (NDVI), were acquired from a hyperspatial flight conducted after a low-moderate exposition to reclaimed waters. Chlorophyll and leaf and palisade/spongy ratio thicknesses were analyzed after a moderate-high exposition. Significant differences between controls and treatments were detected in mandarins in R and leaf chlorophyll, but not in grapefruits, likely because of their higher tolerance to saline waters. Reused waters did not affect either N1R-NDVI or anatomy traits. Hyperspatial sensing techniques are suitable for detecting chlorophyll dynamics, but NIR information and related vegetation indices may mask the detection of periods of saline stress in citrus orchards. [ABSTRACT FROM AUTHOR]

A pilot system was designed and constructed to evaluate reverse osmosis (RO) energy reduction that can be achieved using pressure-retarded osmosis (PRO). The RO-PRO experimental system is the first known system to utilize energy from a volume of water transferred from atmospheric pressure to elevated pressure across a semipermeable membrane to prepressurize RO feedwater. In other words, the system demonstrated that pressure could be exchanged between PRO and RO subsystems. Additionally, the first experimental power density data for a RO-PRO system is now available. Average experimental power densities for the RO-PRO system ranged from 1.1 to 2.3 W/m². This is higher than previous river-to-sea PRO pilot systems (1.5 W/m²) and closer to the goal of 5 W/m² that would make PRO an economically feasible technology. Furthermore, isolated PRO system testing was performed to evaluate PRO element performance with higher cross-flow velocities and power densities exceeding 8 W/m² were achieved with a 28 g/L NaCl draw solution. From this empirical data, inferences for future system performance can be drawn that indicate future RO-PRO systems may reduce the specific energy requirements for desalination by ~1 kWh/m³. [ABSTRACT FROM AUTHOR]

Wave-driven reverse osmosis desalination systems can be a cost-effective option for providing a safe and reliable source of drinking water for large coastal communities. Such systems usually require the stabilization of pulsating pressures for desalination purposes. The key challenge is to convert a fluctuating pressure flow into a constant pressure flow. To address this task, stub-filters, accumulators, and radially elastic-pipes are considered for smoothing the pressure fluctuations in the flow. An analytical model for fluidic capacitance of accumulators and elastic pipes are derived and verified. Commercially available accumulators in combination with essentially rigid (and low cost) piping are found to be a cost-effective solution for this application, and a model for selecting accumulators with the required fluidic-capacitance for the intended system is thus presented. [ABSTRACT FROM AUTHOR]

Abstract: This work deals with comparison among different configurations of the hybrid solar powered desalination system. A hybrid desalination system based on air humidification and dehumidification–single stage flashing (HDH–SSF) has been investigated for different configurations. The main effective arrangement parameters and operating conditions that give minimum water cost and maximum performance are shown. The characteristics of this system in different layouts and working conditions are studied in order to evaluate four main parameters; water cost, water production, thermal performance and environmental impacts. Four configurations are analyzed for HDH–SSF desalination system including the conventional system, which is formed by HDH and SSF unit in standalone layout in addition to three different configurations of hybrid and standalone layouts. The present study covered one year of system operation, in summer and winter for typical climate conditions of the Tanta, Egypt. The most important parameters for the proposed system performance were the heat recovery by mixing tank and air preheating. The hybrid HDH–SSF with solar air heater resulted as the best economical configuration with daily water production up to 96l in August and a production cost of 12.53$/m3. The efficiency of the system is measured by the gained output ratio (GOR) with day time. The standalone HDH–SSF with heat recovery resulted as the best performing one with gained output ratio (GOR) about 10.2. [Copyright &y& Elsevier]

This study investigates a new approach to fabricate thin-film composite (TFC) hollow fiber membranes via interfacial polymerization for forward osmosis (FO) applications. Different degrees of sulfonation of polyphenylenesulfone (PPSU) were adopted as membrane substrates to investigate their impact on water flux. It has been established that the degree of sulfonation plays a role in both creating a macrovoid-free structure and inducing hydrophilicity to bring about higher water fluxes. The fabricated membranes exhibit extremely high water fluxes of 30.6 and 82.0 LMH against a pure water feed using 2.0 M NaCl as the draw solution tested under FO and pressure retarded osmosis (PRO) modes, respectively, while maintaining low salt reverse fluxes below 12.7 gMH. The structural parameter (S) displays remarkable decreases of up to 4.5 times as the membrane substrate is switched from a nonsulfonated to sulfonated one. In addition, the newly developed TFC-FO membranes containing 1.5 mol % sPPSU in the substrate achieves a water flux of 22 LMH in seawater desalination using a 3.5 wt % NaCl model solution and 2.0 M NaCl as the draw solution under the PRO mode. To the best of our knowledge, this value is the highest ever reported for seawater desalination using flat and hollow fiber FO membranes. The use of sulfonated materials in the FO process opens up a frontier for sustainable and efficient production of potable water. [ABSTRACT FROM AUTHOR]

Second Law efficiency is a useful parameter for characterizing the energy requirements of a system in relation to the limits of performance prescribed by the Laws of Thermodynamics. However, since energy costs typically represent less than 50% of the overall cost of product for many large-scale plants (and, in particular, for desalination plants), it is useful to have a parameter that can characterize both energetic and economic effects. In this paper, an economics-based Second Law efficiency is defined by analogy to the exergetic Second Law efficiency and is applied to several desalination systems. It is defined as the ratio of the minimum cost of producing a product divided by the actual cost of production. The minimum cost of producing the product is equal to the cost of the primary source of energy times the minimum amount of energy required, as governed by the Second Law. The analogy is used to show that thermodynamic irreversibilities can be assigned costs and compared directly to non-energetic costs, such as capital expenses, labor and other operating costs. The economics-based Second Law efficiency identifies costly sources of irreversibility and places these irreversibilities in context with the overall system costs. These principles are illustrated through three case studies. First, a simple analysis of multistage flash and multiple effect distillation systems is performed using available data. Second, a complete energetic and economic model of a reverse osmosis plant is developed to show how economic costs are influenced by energetics. Third, a complete energetic and economic model of a solar powered direct contact membrane distillation system is developed to illustrate the true costs associated with so-called free energy sources. [ABSTRACT FROM AUTHOR]

Freshwater shortage is one of the most pressing global issues. Forward osmosis (FO) desalination technology is emerging for freshwater production from saline water, which is potentially more energy-efficient than the current reverse osmosis process. However, the lack of a suitable draw solute is the major hurdle for commercial implementation of the FO desalination technology. We have previously reported that thermoresponsive hydrogels can be used as the draw agent for a FO process, and this new hydrogel-driven FO process holds promise for further development for practical application. In the present work, magnetic field-induced heating is explored for the purpose of developing a more effective way to recover water from swollen hydrogel draw agents. The composite hydrogel particles are prepared by copolymerization of sodium acrylate and N-isopropylacrylamide in the presence of magnetic nanoparticles (γ-Fe2O3, <50 nm). The results indicate that the magnetic heating is an effective and rapid method for dewatering of hydrogels by generating the heat more uniformly throughout the draw agent particles, and thus, a dense skin layer commonly formed via conventional heating from the outside of the particle is minimized. The FO dewatering performance is affected by the loading of magnetic nanoparticles and magnetic field intensity. Significantly enhanced liquid water recovery (53%) is achieved under magnetic heating, as opposed to only around 7% liquid water recovery obtained via convection heating. Our study shows that the magnetic heating is an attractive alternative stimulus for the extraction of highly desirable liquid water from the draw agent in the polymer hydrogel-driven forward osmosis process. [ABSTRACT FROM AUTHOR]

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