Novel graphene quantum dots (GQDs)-incorporated thin film composite (TFC) membranes for forward osmosis (FO) desalination Desalination (IF 5.527) Pub Date : 2018-05-05 Shengjie Xu, Feng Li, Baowei Su, Michael Z. Hu, Xueli Gao, Congjie Gao
This paper reports a novel class of thin film composite (TFC) membranes for forward osmosis (FO) desalination. The TFC membranes were fabricated via interfacial polymerization (IP) of aqueous mixture of polyethyleneimine (PEI) and graphene quantum dots (GQDs) with organic solution of trimesoyl chloride (TMC) on modified polyacrylonitrile (PAN) ultrafiltration substrates. The chemical structures and morphologies of the synthesized GQDs and the GQDs-incorporated membranes were studied by various characterization techniques. The synthesized GQDs exhibited a narrow size distribution of 1.0–4.0 nm with an average size of 2.19 nm, and the thickness were one to three graphene layers. The results showed that GQDs nanoparticles were covalently bonded to the polyamide chains. The optimized TFC membrane with 0.050 wt% GQDs loading exhibited quite hydrophilic and neutrally charged membrane surface, along with an enhanced water flux of 12.9 L m−2 h−1 and a comparable reverse salt flux of 1.41 g m−2 h−1 when DI water and 0.5 M MgCl2 were used as the feed solution and the draw solution, respectively. Also, the optimized GQDs-incorporated TFC membrane presented an especially good anti-fouling performance. Thus, incorporating the novel graphene nanomaterial into polymer membranes may present its great potential application in desalination, purification and wastewater treatment.
Evaluation of NF membranes as treatment technology of acid mine drainage: metals and sulfate removal Desalination (IF 5.527) Pub Date : 2018-04-13 J. Lopez, M. Reig, O. Gibert, C. Valderrama, J.L. Cortina
Acid mine drainage (AMD) are acidic streams rich in dissolved ferrous and non-ferrous metal sulfates and minor amounts of non-metals. Nanofiltration (NF) has been postulated as a potential technology in the metallurgical and mining industry to recover strong acids as H2SO4 and concentrate metallic ions from acidic mine waters. The performance of semi-aromatic polyamide (NF270) and sulfonated polyethersulfone (HydraCoRe 70pHT) NF membranes were evaluated at different trans-membrane pressures. Different synthetic solutions were filtered under spiral wound configuration at two pHs (2.0 and 2.8): i) a solution of Na2SO4 and ii) a solution mimicking AMD from dams, containing Na2SO4 and Fe2+, Zn2+ and Cu2+. NF270 showed metal rejections higher than 90%, while for HydraCoRe 70pHT they were in between 60 and 70%. Metal rejection values decreased when solution acidity was increased. Chemical composition of the membrane active layer and the aqueous metal-sulfate speciation were found to have a large impact on membrane separation process. Solution-Electromigration-Diffusion-Film model was used to estimate the membrane permeances to ions from the measured ion rejections. Furthermore, a full scale unit vessel containing six spiral wound membrane modules was simulated. NF270 showed a higher capacity for concentrating metal and sulfate ions (100%) than Hydracore 70pHT (50%).
Development of a novel graphene/Co3O4 composite for hybrid capacitive deionization system Desalination (IF 5.527) Pub Date : 2018-04-04 Govindaraj Divyapriya, Keshav Kumar Vijayakumar, Indumathi Nambi
Recently, hybrid capacitive deionization devices have gathered much attention due to high ion removal capacity, rapid ion capture and excellent stability. In this study, sodium ion battery material-reduced graphene oxide/cobalt oxide (rGO/Co3O4) has been successfully synthesized and investigated as a potential cathode for hybrid capacitive deionization (HCDI) systems for the first time. The structure and morphology of rGO and rGO/Co3O4 composites have been analyzed using XRD, FT-IR, TGA and SEM. The characterization confirms the homogeneous crystal growth of Co3O4 on the rGO sheets, with rGO weight % of 9.4 (rGO/Co3O4-A) and 25.2 (rGO/Co3O4-B). The cyclic voltammetry studies indicated that the rGO/Co3O4-B electrode exhibited high specific capacitance (210 F g−1 at 5 mV s−1) with redox properties. This paper also investigates the influence of initial concentration and voltage on the ion removal capacity of the rGO and rGO/Co3O4 composites. The rGO/Co3O4-B based HCDI system presents a significantly high ion removal capacity of 18.63 mg g−1 (250 mg L−1, 1.6 V), which is 2.8 times higher than pure rGO based CDI system (6.45 mg g−1). Also, the rGO/Co3O4 composites exhibited excellent regeneration ability indicating its potential use in high performance CDI systems.
Effects of oscillating pressure on desalination performance of transverse flow CNT membrane Desalination (IF 5.527) Pub Date : 2018-04-03 Elisa Y.M. Ang, Teng Yong Ng, Jingjie Yeo, Zishun Liu, Rongming Lin, K.R. Geethalakshmi
Performance of ceramic membrane in vacuum membrane distillation and in vacuum membrane crystallization Desalination (IF 5.527) Pub Date : 2018-03-30 Chia-Chieh Ko, Aamer Ali, Enrico Drioli, Kuo-Lun Tung, Chien-Hua Chen, Yi-Rui Chen, Francesca Macedonio
Membrane crystallization (MCr) is emerging as an interesting candidate to extract additional freshwater and raw materials from high-concentrated solutions. Traditionally, MCr has been carried out by using polymeric membranes that have limited chemical and mechanical stability. These shortcomings can be overcome by using ceramic membranes. The current study describes the preparation and testing of two hydrophobic ceramic membranes synthesized trough sol-gel process, and combined phase-inversion and sintering method. The first membrane (CM-L) was synthesized by coating hydrophobic polymethylsilsesquioxane aerogels on alumina membrane supports via a sol-gel process. The membrane showed stable hydrophobic character in membrane distillation and crystallization tests but very low flux. To obtain high flux, a second type (CM-S) membrane was prepared by applying Fluoroalkylsilanes (FAS) (1H, 1H, 2H, 2H‑perfluorooctyltriethoxysilane) hydrophobic agent at the relatively thin and more porous as-sintered alumina hollow fibers. The suitability of both membranes for MCr process was analyzed by crystallizing NaCl and LiCl. By using 1 M NaCl and 13 M LiCl aqueous solutions, and under the same operative conditions, CM-S membrane exhibited average flux higher than CM-L membrane. The performance of both the membranes, in terms of hydrophobic character, remained stable throughout the performed tests.
Sulfonated poly(ether ether ketone)/imidized graphene oxide composite cation exchange membrane with improved conductivity and stability for electrodialytic water desalination Desalination (IF 5.527) Pub Date : 2018-03-26 Geetanjali Shukla, Vinod K. Shahi
Support based novel single layer nanoporous graphene membrane for efficacious water desalination Desalination (IF 5.527) Pub Date : 2018-03-19 Asieh Sadat Kazemi, Yaser Abdi, Javad Eslami, Rasel Das
Produced water impact on membrane integrity during extended pilot testing of forward osmosis – reverse osmosis treatment Desalination (IF 5.527) Pub Date : 2018-03-15 Rudy A. Maltos, Julia Regnery, Nohemi Almaraz, Shalom Fox, Mark Schutter, Tani J. Cath, Michael Veres, Bryan D. Coday, Tzahi Y. Cath
Forward osmosis (FO) has proven to be a robust, low-pressure membrane separation process capable of rejecting a broad range of contaminants; thus, providing a high quality diluted brine suitable for further desalination by reverse osmosis (RO). In this study, a pilot-scale FO-RO system treated >10,000 L of raw produced water from the Denver-Julesburg basin (Colorado) over a four-week period using commercially available FO and RO membranes. Overall, the FO-RO pilot system maintained >99% rejection of nearly all measured ions and >95% rejection of hydrocarbons such as semi-volatile linear aliphatic hydrocarbons and polycyclic aromatic hydrocarbons. Although the FO-RO system was able to treat raw produced water, high concentrations of organic compounds severely fouled the FO membrane and substantially reduced water flux by 68% within 21 days. Membrane degradation due to interaction between organic constituents such as aliphatic and aromatic hydrocarbons and the membrane polymer may have compromised the FO membranes, resulting in substantial increase (×15) in reverse salt flux within 21 days. Further investigations of membrane cleaning and pretreatment will be required in order to better understand the overall economic feasibility of treating raw produced water using FO.
Investigation of off-grid photovoltaic systems for a reverse osmosis desalination system: A case study Desalination (IF 5.527) Pub Date : 2018-03-15 Ali Mostafaeipour, Mojtaba Qolipour, Mostafa Rezaei, Erfan Babaee-Tirkolaee
There has been a great concern about shortage of potable water in many countries as well as Iran, because of the dramatic low rainfall during past few decades almost in all over the Iran. There is a great concern for implementing renewable desalination systems as it seems to be the only clean and environmental friendly source to the traditional fossil fuel powered systems. This study sought to simultaneously assess the reliability of electricity and cost in off grid photovoltaic systems for a photovoltaic reverse osmosis desalination system in 9 districts of Bushehr Province in Iran. Solar data used in this study contains indices of “Clearness Index” and “Daily Solar Radiation” over a period of 16 years from 2000 to 2016. HOMER and Excel were used for technical-economic feasibility of the proposed systems. For this study, a new model of BWRO-2S-130/75 desalination system is tested and proposed. The results indicate that the proposed photovoltaic systems are technically and economically feasible. It was also found that the reliability of off grid photovoltaic system using fuzzy time function provided better results than using the simple method. The results of the evaluation of proposed photovoltaic systems by HOMER software shows that annual electricity production for Delvar and Deylam port are 72,336 and 47,915 kWh respectively which is promising. Also, maximum of 228 m3 and a minimum of 148 m3/day of potable water can be produced with cost of 1.96 to 3.02 $/m2 for Delvar and Deylam port respectively. Results indicate that using the proposed system of desalination would be economically feasible for Delvar, since the predicted water cost is cheaper compared to existing water price of $2.5. The new model of BWRO-2S-130/75 desalination can meet the water demand of the selected city.
Overcoming temperature polarization in membrane distillation by thermoplasmonic effects activated by Ag nanofillers in polymeric membranes Desalination (IF 5.527) Pub Date : 2018-03-14 Antonio Politano, Gianluca Di Profio, Enrica Fontananova, Vanna Sanna, Anna Cupolillo, Efrem Curcio
In recent years, Membrane Distillation (MD) has emerged either as a promising alternative or as a complement to Reverse Osmosis (RO) in seawater desalination. However, the performance of MD is significantly offset by temperature polarization, a phenomenon intrinsically related to water evaporation that causes the decrease of the solution temperature at the membrane surface and, ultimately, the loss of driving force. In this work, we show that temperature polarization can be withdrawn by exploiting thermal collective effects activated by the excitation of plasmonic modes in UV-irradiated Mixed Matrix Membranes composed of silver nanoparticles (Ag NPs) incorporated in polyvinylidene fluoride (PVDF) microporous films. For experimental tests carried out under vacuum (VMD) and with an absorbed radiant heating power of 2.3 · 104 W/m2, best results were obtained using PVDF membranes loaded with 25%Ag NPs. In this case, measured transmembrane fluxes to pure water and 0.5 M NaCl solution were 32.2 and 25.7 L/m2 h, respectively, i.e. about 11- and 9- fold higher than the corresponding values for unloaded membranes. Remarkably, energy analysis revealed that the heat generation of Ag NPs under plasmonic resonance was able to withdrawn temperature polarization, resulting in estimated temperature polarization factor (TPF) values of 106.5% for 0.5 M NaCl solution.
Integrated UF–NF–RO route for gold mining effluent treatment: From bench-scale to pilot-scale Desalination (IF 5.527) Pub Date : 2018-03-07 Míriam C.S. Amaral, Luiza B. Grossi, Ramatisa L. Ramos, Bárbara C. Ricci, Laura H. Andrade
This study focused on the performance of an UF–NF–RO integrated system treating a gold mining effluent from the pressure-oxidation stage in order to concentrate metals, and recover acid and water. Aspects such as the most suitable cross-flow velocity, cleaning procedure, and water recovery fraction were evaluated. For cross-flow velocities, a threshold value of 1.5 × 10−2 m/s was found for NF and RO stages. Besides, the system had its best performance while operating at recovery fractions of 90%, 40–50%, and 50% for UF, NF, and RO, respectively. Concentration factors of 2.0 and 2.7 were found in metals from the NF retentate and sulfuric acid from the RO retentate respectively. For cleaning purposes, hydrochloric and oxalic acid demonstrated the best cost-benefit. A long-term operation inside the mining company was assessed and the results confirmed that NF and RO association allowed for the recovery of a purified acid stream, which may be reused in the ore processing; the production of a metal enriched stream, that can be transferred to a subsequent metal recovery stage; and the generation of high quality reuse water. The total cost of the proposed route was US$ 1.137/m3 of effluent, including UF and NF concentrate neutralisation.
A direct comparison of flow-by and flow-through capacitive deionization Desalination (IF 5.527) Pub Date : 2018-02-27 E. Marielle Remillard, Amit N. Shocron, John Rahill, Matthew E. Suss, Chad D. Vecitis
Development and performance evaluation of an active solar distillation system integrated with a vacuum-type heat exchanger Desalination (IF 5.527) Pub Date : 2018-02-19 Ali Hosseini, Ahmad Banakar, Shiva Gorjian
Hybrid desalination processes for beneficial use of reverse osmosis brine: Current status and future prospects Desalination (IF 5.527) Pub Date : 2018-02-16 Sangho Lee, Juneseok Choi, Yong-Gyun Park, Hokyong Shon, Chang Hoon Ahn, Seung-Hyun Kim
As water shortage has increasingly become a serious global problem, desalination using seawater reverse osmosis (SWRO) is considered as a sustainable source of potable water sources. However, a major issue on the SWRO desalination plant is the generation of brine that has potential adverse impact due to its high salt concentration. Accordingly, it is necessary to develop technologies that allow environmentally friendly and economically viable management of SWRO brines. This paper gives an overview of recent research works and technologies to treat SWRO brines for its beneficial use. The treatment processes have been classified into two different groups according to their final purpose: 1) technologies for producing fresh water and 2) technologies for recovering energy. Topics in this paper includes membrane distillation (MD), forward osmosis (FO), pressure-retarded osmosis (PRO), reverse electrodialysis (RED) as emerging tools for beneficial use of SWRO brine. In addition, a new approach to simultaneously recover water and energy from SWRO brine is introduced as a case study to provide insight into improving the sustainability of seawater desalination.
Exergy analysis of membrane capacitive deionization (MCDI) Desalination (IF 5.527) Pub Date : 2018-02-15 Pina A. Fritz, F.K. Zisopoulos, S. Verheggen, K. Schroën, R.M. Boom
Capacitive deionization (CDI) and membrane capacitive deionization (MCDI) are widely considered as promising, highly energy efficient processes for water desalination, of which commonly used performance indicators are the average salt adsorption rate, the salt removal efficiency, and the charge efficiency. Quantification of the sustainability performance of CDI and MCDI is still scarce, and in this paper, we use exergy analysis to evaluate the resource use efficiency of membrane capacitive deionization (MCDI). The electric as well as chemical exergies of the salt solution, and the stored ions, are used to calculate the exergy efficiency (ηex) and cumulative exergy losses (CEL) ranging between 2 to 13% and 0.5 to 8 J/mol water, respectively. From an exergetic point of view, passive adsorption in combination with active desorption (−0.9 V) is favorable, yielding the highest ηex and lowest CEL values. The combination of active salt adsorption using an electric field, with either passive or active desorption gives higher productivities, but at the cost of a disproportionate amount of exergy (and energy) input.
Effect of a porous spacer on the limiting current density in an electro-dialysis desalination Desalination (IF 5.527) Pub Date : 2018-02-14 Yoshihiko Sano, Xiaohui Bai, Shuzen Amagai, Akira Nakayama
A series of experiments have been carried out to examine the performance of porous spacers proposed for increasing the limiting current density, since it is of fundamental importance to find an optimal operate condition in an electro-dialysis. The fluid mixing in the porous material can play an important role to suppress the concentration polarization and achieve a high limiting current density. The effect of porous spacers filled in both dilute and concentrate channels on the stack voltage and the limiting current density has been investigated by comparing the cases with and without porous spacers. It has been found that the limiting current density with porous spacers is 1.8 to 3.3 times higher than that without a porous spacer as a result of mechanical dispersion caused by fluid mixing in porous materials. Furthermore, the increase ratio of limiting current density with the present spacers to that without spacer is higher than that of conventional mesh spacers. Moreover, it was found that the electrical resistance does not increase even when inserting the present porous spacers by comparing that of conventional mesh spacers, since the present porous spacer can suppress the concentration polarization concerned with electrical resistance. On the other hand, the increase in the pumping power turns to be negligible small by comparing the electrical power for an electro-dialysis since permeability of the present spacers is sufficiently high. In this study, it has been proven that the insertion of porous spacers is quite useful in terms of limiting current density, electrical resistance and pumping power.
Membrane selective recovery of HCl, zinc and iron from simulated mining effluents Desalination (IF 5.527) Pub Date : 2018-02-13 M. Fresnedo San Román, Isabel Ortiz-Gándara, Eugenio Bringas, Raquel Ibañez, Inmaculada Ortiz
This work proposes a flowsheet based on the combination of membrane processes for the effective recovery of value-added components contained in mining effluents with high concentration of hydrochloric acid and metal anionic and cationic chloro-complexes. A representative case of study has been selected consisting of a solution of zinc and iron that under the studied conditions were solubilized forming anionic and cationic chloro-complexes. The high complexity of the system requires of a selective membrane-based solvent extraction step to successfully achieve the separation of cationic iron from a solution containing the acid together with anionic species of zinc followed by a diffusion process through ion conductive membranes for acid recovery; in this step electrodialysis was selected searching for the optimum trade-off between process kinetics and separation selectivity. Although the quantitative results are case-dependent, the methodology can be well extended to any mining leaching effluent coming from the use of HCl as leaching agent and containing metal chloro-complexes.
Low energy consumption dual-ion electrochemical deionization system using NaTi2(PO4)3-AgNPs electrodes Desalination (IF 5.527) Pub Date : 2018-02-13 Yinxi Huang, Fuming Chen, Lu Guo, Jun Zhang, Tupei Chen, Hui Ying Yang
Novel desalination technologies with high ion removal capacity and low energy consumption are urgently needed to solve the water scarcity problem. Here we report a novel energy efficient dual-ions electrochemical deionization (DEDI) system with Ag nanoparticles/reduced graphene-oxide (AgNPs/rGO) as chloride ion Faradaic electrode and NaTi2(PO4)3/reduced graphene-oxide (NTP/rGO) as sodium ion Faradaic electrode. During the intercalation process, the sodium ions and chloride ions in the feed solution will be chemically intercalated into NTP/rGO electrode and AgNPs/rGO electrode, respectively. The DEDI system shows a stable and reversible salt removal capacity of 105 mg g−1 for 50 cycles with applied voltage range of −1.2–1.4 V. More importantly, when applying from 0 V to 1.4 V, although the removal capacity is relatively low (35.8 mg g−1), the energy recovery of this system is higher than 30% and the energy consumption is as low as 0.127 Wh g−1. Considering the brackish water used here is 2500 ppm, the energy consumption can be estimated to be 0.254 Wh L−1 for desalination of brackish water to drinkable water (500 ppm). The excellent performance of this DEDI system has made it a promising commercial technology for desalination of brackish water even seawater in the future.
Electrodialysis for water desalination: A critical assessment of recent developments on process fundamentals, models and applications Desalination (IF 5.527) Pub Date : 2018-02-12 A. Campione, L. Gurreri, M. Ciofalo, G. Micale, A. Tamburini, A. Cipollina
The need for unconventional sources of fresh water is pushing a fast development of desalination technologies, which proved to be able to face and solve the problem of water scarcity in many dry areas of the planet. Membrane desalination technologies are nowadays leading the market and, among these, electrodialysis (ED) plays an important role, especially for brackish water desalination, thanks to its robustness, extreme flexibility and broad range of applications. In fact, many ED-related processes have been presented, based on the use of Ion Exchange Membranes (IEMs), which are significantly boosting the development of ED-related technologies. This paper presents the fundamentals of the ED process and its main developments. An important outlook is given to operational aspects, hydrodynamics and mass transport phenomena, with an extensive review of literature studies focusing on theoretical or experimental characterization of the complex phenomena occurring in electromembrane processes and of proposed strategies for process performance enhancement. An overview of process modelling tools is provided, pointing out capabilities and limitations of the different approaches and their possible application to optimisation analysis and perspective developments of ED technology. Finally, the most recent applications of ED-related processes are presented, highlighting limitations and potentialities in the water and energy industry.
Quantitative sustainability analysis of water desalination – A didactic example for reverse osmosis Desalination (IF 5.527) Pub Date : 2018-02-03 Noam Lior, David Kim
Water desalination continues to evolve to a currently mature stage that, similarly to all large human endeavors, must be planned, designed, and operated according to the quantitative holistic sustainability paradigm and criteria that are defined by the interrelated aspects of the environmental, economic, and social pillars of the endeavor. A methodology for such evaluation was described in , including equations for formulating a composite sustainability index as a function of relevant parameters, which thus allows mathematical analysis in general and sensitivity analysis and optimization in particular. This is the first paper that demonstrates this methodology and its use for desalination by presenting an example of a comprehensive and detailed original sustainability analysis of reverse osmosis (RO) desalination plants and of their comparison. It includes the selection and calculation of metrics (for simplicity, a small number and partially synthetic) and weights, as well as their aggregation to a composite sustainability indicator, using typical data values. The aggregation is performed by an original concept of impact quantification and monetization. An analysis of sensitivity to choice of weights and to the combined environmental and social impact factors was conducted. The presented sustainability analysis example should be helpful for both didactic and practical purposes, and the methodology is flexible, modular, adaptable, and enhancable to meet other and evolving needs.
State of the art review on membrane surface characterisation: Visualisation, verification and quantification of membrane properties Desalination (IF 5.527) Pub Date : 2017-03-20 Daniel J. Johnson, Darren L. Oatley-Radcliffe, Nidal Hilal
Many of the properties exhibited by separation membranes are due to interactions at the interface with their environment, including flux, rejection of solutes and surface fouling. As such when trying to understand how such interactions affect their function and when developing novel membranes with improved properties, a thorough understanding of their surface properties is essential. In this review paper we describe and discuss a number of instrumental techniques commonly used to characterize membrane surface, along with illustrative examples from the literature on membrane development and characterisation. The techniques described include spectroscopic techniques, microscopic techniques and methods to measure the surface wettability and electrokinetic behaviour.
Dynamic solar-powered multi-stage direct contact membrane distillation system: Concept design, modeling and simulation Desalination (IF 5.527) Pub Date : 2017-04-26 Jung-Gil Lee, Woo-Seung Kim, June-Seok Choi, Noreddine Ghaffour, Young-Deuk Kim
This paper presents a theoretical analysis of the monthly average daily and hourly performances of a solar-powered multi-stage direct contact membrane distillation (SMDCMD) system with an energy recovery scheme and dynamic operating system. Mid-latitude meteorological data from Busan, Korea is employed, featuring large climate variation over the course of one year. The number of module stages used by the dynamic operating scheme changes dynamically based on the inlet feed temperature of the successive modules, which results in an improvement of the water production and thermal efficiency. The simulations of the SMDCMD system are carried out to investigate the spatial and temporal variations in the feed and permeate temperatures and permeate flux. The monthly average daily water production increases from 0.37 m3/day to 0.4 m3/day and thermal efficiency increases from 31% to 45% when comparing systems both without and with dynamic operation in December. The water production with respect to collector area ranged from 350 m2 to 550 m2 and the seawater storage tank volume ranged from 16 m3 to 28.8 m3, and the solar fraction at various desired feed temperatures from 50 °C to 80 °C have been investigated in October and December.
A direct contact type ice generator for seawater freezing desalination using LNG cold energy Desalination (IF 5.527) Pub Date : 2017-04-27 Chungang Xie, Lingpin Zhang, Yanhui Liu, Qingchun Lv, Guoling Ruan, Seyed Saeid Hosseini
Analysis of specific energy consumption in reverse osmosis desalination processes Desalination (IF 5.527) Pub Date : 2017-05-03 A.J. Karabelas, C.P. Koutsou, M. Kostoglou, D.C. Sioutopoulos
This paper aims to quantify the contribution of the various factors to energy consumption in reverse osmosis (RO) desalination processes and to identify those with the greatest potential for reduction. Specific energy consumption (SEC), in kWh per m3 of permeate production, is due to the retentate osmotic pressure, the resistance to fluid permeation through the membrane, the friction losses in the retentate and permeate channels of the spiral wound membrane (SWM) modules and the non-ideal operation of high pressure pumps and energy recovery devices (ERD). Taking advantage of a recently developed SWM-module performance simulator, the aforementioned individual contributions to SEC are determined for two case studies, typical of seawater and brackish water desalination processes, for steady state operation. Detailed results are obtained with SEC itemized per SWM element in a typical 7-element pressure vessel. Comparative assessment of the results is enlightening, showing that the greatest margin for the desirable SEC reduction is related to improvements of membrane permeability and efficiency of pumps and ERD. The indirect, yet significant, effect of other key design and operating process parameters is also discussed.
Integrated PV/T solar still- A mini-review Desalination (IF 5.527) Pub Date : 2017-05-03 A. Muthu Manokar, D. Prince Winston, A.E. Kabeel, S.A. El-Agouz, Ravishankar Sathyamurthy, T. Arunkumar, B. Madhu, Amimul Ahsan
Water is a critical component for living existence on earth. Clean water is the need of hour, but the amount of clean water available in earth is drastically reduced due to water pollution caused by industrialization and rapid urbanization. Overall global climatic and seasonal changes also have a significant impact on the reduction of amount of fresh water. The need for clean water is continuously growing due to rise in human residents for the last few decades. Use of contaminated water leads to several water borne diseases and based on the intensity of contamination sometimes it leads to death. There are various processes for obtaining fresh water from contaminated water, but the most economical and preferable method is solar distillation since the process involved in it is similar to natural hydrological cycle which requires only solar energy for its operation. Solar stills are potable and do not require any additional skills for its operation and maintenance which makes it user friendly. Integrated PV/T solar still is used for isolated communities facing electrical energy troubles and a scarcity of good quality water. The daily fresh water produced from passive solar still was found to be 2–5 kg/m2 whereas from an active solar still integrated with PV/T collector can produced daily yield of about 6–12 kg/m2. In this paper, a comprehensive review of integration of solar still and PV module has been presented.
A multi evaporator desalination system operated with thermocline energy for future sustainability Desalination (IF 5.527) Pub Date : 2017-05-05 Muhammad Wakil Shahzad, Muhammad Burhan, Noreddine Ghaffour, Kim Choon Ng
All existing commercial seawater desalination processes, i.e. thermally-driven and membrane-based reverse osmosis (RO), are operated with universal performance ratios (UPR) varying up to 105, whilst the UPR for an ideal or thermodynamic limit (TL) of desalination is at 828. Despite slightly better UPRs for the RO plants, all practical desalination plants available, hitherto, operate at only less than 12% of the TL, rendering them highly energy intensive and unsustainable for future sustainability. More innovative desalination methods must be sought to meet the needs of future sustainable desalination and these methods should attain an upper UPR bound of about 25 to 30% of the TL. In this paper, we examined the efficacy of a multi-effect distillation (MED) system operated with thermocline energy from the sea; a proven desalination technology that can exploit the narrow temperature gradient of 20 °C all year round created between the warm surface seawater and the cold-seawater at depths of about 300–600 m. Such a seawater thermocline (ST)-driven MED system, simply called the ST-MED process, has the potential to achieve up to 2 folds improvement in desalination efficiency over the existing methods, attaining about 18.8% of the ideal limit. With the major energy input emanated from the renewable solar, the ST-MED is truly a “green desalination” method of low global warming potential, best suited for tropical coastal shores having bathymetry depths of 300 m or more.
Desalination using low biofouling nanocomposite membranes: From batch-scale to continuous-scale membrane fabrication Desalination (IF 5.527) Pub Date : 2017-05-17 Sneha Chede, Nelson M. Anaya, Vinka Oyanedel-Craver, Sanam Gorgannejad, Tequila A.L. Harris, Jumana Al-Mallahi, Muna Abu-Dalo, Hani Abu Qdais, Isabel C. Escobar
This study shows the results of low-biofouling nanocomposite membranes, when using batch-scale fabrication and testing techniques, and when using continuous-scale fabrication and testing techniques. This holistic study begins with nanoparticle manufacturing and selection, then focuses on nanocomposite membrane synthesis and fabrication, and ends with testing and characterization. Nanocomposite membranes loaded with casein-coated silver nanoparticles (Casein-AgNPs) were cast using two approaches, doctor-blade extrusion (batch-scale) and slot-die casting (continuous-scale), to determine their biofouling control properties. In short-term dead-end filtration, cellulose acetate (CA) membranes showed a flux decline of approximately 26% as compared to 20% for nanocomposite (Casein-AgNPs CA) membranes, while the flux recovered after backwashing was higher for the nanocomposite membranes (93%) than for the CA membranes (84%). Cross-flow filtration experiments were conducted for 26 days. No flux decline was observed for nanocomposite membranes and SEM imaging indicated that bacterial cell damage might have occurred. Overall, filtration experiments and membrane testing following biofouling tests showed that laboratory-scale composite membranes operated for 24 h were effective in mitigating biofouling formation. Conversely, continuous-scale nanocomposite membranes operated for 26 days did not show clear improvement in biofouling control, however there was visible damage to cells accumulated on the membrane.
Hydrotalcite/graphene oxide hybrid nanosheets functionalized nanofiltration membrane for desalination Desalination (IF 5.527) Pub Date : 2017-05-18 Xue Wang, Huixian Wang, Yuanming Wang, Jian Gao, Jindun Liu, Yatao Zhang
Study on parameters effective on the performance of a humidification-dehumidification seawater greenhouse using support vector regression Desalination (IF 5.527) Pub Date : 2017-06-02 Taleb Zarei, Reza Behyad, Ehsan Abedini
A Seawater greenhouse is a desalination plant that, using solar energy and seawater, humidifies the interior of the greenhouse and produces water from the humid air. The produced water can be used both for irrigation and human consumption. Many factors affect the performance of a seawater greenhouse. In this study, using artificial neural networks, the effects of greenhouse width and length, first evaporator height, and roof transparency on the water production and energy consumption of a seawater greenhouse were examined with the help of Support Vector Regression (SVR) method. A suitable structure was obtained for this method, and %AARE, RMSE and R2 statistic measures were used for evaluating the performance of the network. This method shows the favorable correspondence with experimental data. Using the prepared optimized network, the effect of each parameter on water production and energy consumption was examined for a wide range of variations in the parameter values. Finally, a 125 m wide, 200 m long greenhouse with a 4 m high evaporator and permeability of 0.6 was found to be the optimum configuration, offering a daily water production of 161.6 m3 for 1.558 kWh of energy consumed per cubic meter of water produced.
Integrated approach in eco-design strategy for small RO desalination plants powered by photovoltaic energy Desalination (IF 5.527) Pub Date : 2017-06-09 Mathias Monnot, Germán Darío Martínez Carvajal, Stéphanie Laborie, Corinne Cabassud, Rémi Lebrun
Water vapor selective thin film nanocomposite membranes prepared by functionalized Silicon nanoparticles Desalination (IF 5.527) Pub Date : 2017-06-16 Muhammad Irshad Baig, Pravin G. Ingole, Jae-deok Jeon, Seong Uk Hong, Won Kil Choi, Boyun Jang, Hyung Keun Lee
Graphene oxide–nanobentonite composite sieves for enhanced desalination and dye removal Desalination (IF 5.527) Pub Date : 2017-06-16 Priya Banerjee, Aniruddha Mukhopadhyay, Papita Das
Mesoporous carbon derived from ZIF-8 for high efficient electrosorption Desalination (IF 5.527) Pub Date : 2017-07-04 Tie Gao, Haibo Li, Feng Zhou, Mangmang Gao, Sen Liang, Min Luo
In this work, the capacitive deionization (CDI) behavior of mesoporous carbons (MCs) through direct carbonization of ZIF-8 at 1000 °C under Ar + 4%H2 atmosphere has been explored. The obtained MCs exhibit a well-defined mesoporous structure, with a high specific surface area of 723.41 m2·g− 1 and average pore diameter of 3.2 nm. The specific electrochemical capacitance of MCs was evaluated in a three-electrode configuration with 1 M NaCl electrolyte, showing that the capacitance reached as high as 215.72 F·g− 1 at the scan rate of 5 mV·s− 1 and 186 F·g− 1 with current density of 100 mA·g− 1, respectively. Moreover, it is found that the electrosorption capacity of MCs was 4.8 mg·g− 1 in NaCl solutions with an initial concentration of 250 mg·L− 1 and cell voltage of 1.2 V. Remarkably, the theoretical maximum electrosorption capacity was estimated at 17 mg·g− 1 from Langmuir isotherm when the cell voltage was fixed at 1.2 V. Finally, the well regeneration of MCs electrode was demonstrated, indicating the great potential application of MCs in desalination.
Integration of hybrid power (wind-photovoltaic-diesel-battery) and seawater reverse osmosis systems for small-scale desalination applications Desalination (IF 5.527) Pub Date : 2017-07-18 Murat Gökçek
Desalination is a method used to produce water for human consumption and/or industrial use. Seawater treatment systems powered by renewable sources are regarded as sustainable methods for providing drinking water for coastal zones and islands where there is no electrical grid. This study evaluated the operations of seven different (off-grid) power systems (wind-photovoltaic-diesel-battery) used to satisfy the electrical energy demand of a small-scale reverse osmosis system with a capacity of 1 m3/h used on Bozcaada Island, Turkey. The hybrid optimisation model for electric renewable (HOMER) software was selected to perform techno-economic analyses of the systems. On the other hand, the reverse osmosis system analysis model (ROSA) was used to determine the energy requirement of the reverse osmosis system examined in this study. The results of this study showed that the electricity cost was $0.308/kWh for the optimal system consisting of wind turbines with a rated power of 10 kW, a 20 kW PV panel, and a diesel generator with a rated power of 8.90 kW, while the water cost was $2.20/m3. Additionally, the results showed that combining the hybrid power system and reverse osmosis system could be a cost-effective method for remote areas with good wind and solar power potential.
Filtration characteristics of threaded microfiber water filters Desalination (IF 5.527) Pub Date : 2017-07-20 Hilla Shemer, Abraham Sagiv, Marina Holenberg, Adva Zach Maor
Textile fibers are widely used for fine filtration in the disposable cartridge filter market. In this work the filtration mechanism of threaded microfiber water filters was characterized by testing the effect of filtration velocity, slurry concentration, particles size distribution (PSD) and filter pore size and porosity, on the filter performance. Constant flow rate experiments were conducted with micronized CaCO3 slurry as a model substance. It was found that the predominant filtration mechanism of the studied filters is cake filtration. Very efficient filtration followed by effective automatic cleaning of the filter was obtained as indicated by complete removal of the CaCO3 particles in all the conditions studied and similar clean filter resistance over repetitive cycles. Shorter filtration cycles were obtained at higher velocities, low porosity filter and narrow PSD. Correspondingly, the filter capacity declined as the filtration cycles were shorter. Yet, the filter capacity was found to be independent of the CaCO3 slurry concentration. A criterion of specific consumed energy per unit filtrate volume (Es) was developed. Analyses of the effect of the various studied parameters on Es revealed its dependence on the slurry concentration, velocity and filtration time.
Environmental issues in seawater reverse osmosis desalination: Intakes and outfalls Desalination (IF 5.527) Pub Date : 2017-07-25 Thomas M. Missimer, Robert G. Maliva
Seawater reverse osmosis (SWRO) desalination has some environmental impacts associated with the construction and operation of intake systems and the disposal of concentrate. The primary impact of conventional open-ocean intake systems is the impingement and entrainment of marine organisms. These impacts can be minimized by locating the intake in a geographic position where oceanic productivity is low. Velocity-cap intakes tend to reduce impacts by minimizing the number of fish entrained and some new traveling screens can allow the survival of some marine organisms. Mitigation, such as environmental restoration of habitat or restocking, can provide an acceptable solution to impacts where they are significant. Subsurface intake systems avoid impingement and entrainment impacts, but can cause other, less important impacts (e.g., visual, beach access). Concentrate disposal can locally impact benthic communities, if poorly diluted discharge is allowed to flow across the marine bottom. Impacts to benthic communities from concentrate discharges can be minimized by using properly-designed diffuser systems, designed and located based current and flow modeling. The experiences of SWRO desalination to date indicate that environmental impacts can be satisfactorily minimized with proper design based on a reasonably complete environmental impact analysis prior to facility siting and design.
Polyamide/nitrogen-doped graphene oxide quantum dots (N-GOQD) thin film nanocomposite reverse osmosis membranes for high flux desalination Desalination (IF 5.527) Pub Date : 2017-07-31 Mahdi Fathizadeh, Huynh Ngoc Tien, Konstantin Khivantsev, Zhuonan Song, Fanglei Zhou, Miao Yu
Performance of basin type stepped solar still enhanced with superior design concepts Desalination (IF 5.527) Pub Date : 2017-08-08 Ali.F. Muftah, K. Sopian, M.A. Alghoul
It is difficult maintaining a minimum water depth in a conventional basin type solar still, as the required area is quite large. To overcome this difficulty, the R&D community proposed a stepped solar still in an attempt to increase the production per unit area by decreasing the thermal inertia of the water mass, where the area of the basin is minimized via the utilization of small trays. However, stepped solar still is still potential for further enhancement. It is leaned from the literature, that adding internal and external reflectors, absorber materials (fins) and external condensers are considered superior in enhancing the absorption, evaporation and condensation processes of the basin type solar still. Combining these design concepts concurrently with stepped solar still to enhance its performance is still a missing link in the literature. In this study, a previous work of stepped solar still is selected to apply these modifications on it and propose it as a new design. Energy balance model is developed to compare the performance of the stepped solar still before and after modification. The energy balance results are obtained by solving the energy balance equations for various elements: absorber plate, saline water and glass cover of the solar still. Hourly solar radiation and hourly ambient temperature of clear sky day conditions are used as input data in the energy balance model. The hourly performance of the stepped solar still is compared before and after modification under the following evaluation parameters: temperature difference between saline water and glass cover, evaporation/convective/radiative heat transfer coefficients, solar still productivity and solar still efficiency. The results showed that the hourly values of evaluation parameters after modification are always higher of that before modification. This increment is tested statistically to confirm its significance. So, the differences in the mean values of each evaluation parameter before and after modification are tested by statistical paired t-test. The test results confirmed that there is a significant difference in the mean values of each evaluation parameter before and after modification. Moreover, the daily productivity of the stepped solar still after modification increased from 6.9 to 8.9 kg/m2; this represents 29% enhancement compared to before modification. Finally, based on the results of the evaluation parameters and the statistical test, the thermal performance of the proposed stepped solar still is considerably improved through the new modification.
A review on inorganic membranes for desalination and wastewater treatment Desalination (IF 5.527) Pub Date : 2017-08-12 P.S. Goh, A.F. Ismail
The sustainability of global clean and safe water supply is one of the grand challenges facing the world. Membrane technology based on polymeric membranes is one of the most important and widely recognized technologies for desalination and wastewater treatment. While polymeric membranes are known to be plagued with some bottlenecks, the technical progress and the accompanying knowledge in inorganic membrane development have grown inexorably to solve some of the underlying issues. Aside from the conventionally used ceramic membranes which based on metal oxides, nanostructures such as zeolites, metal organic frameworks and carbon based materials have sparked enormous interest in the preparation of inorganic membranes owing to their tunable nanoscaled structural properties that can render excellent rejection and/or ultrafast water transport. This review provides insights into the physico-chemical properties and fabrication approaches of different classes of inorganic membranes. The transport mechanisms that are associated to their unique structural features are also discussed. Furthermore, the performance evaluation of these inorganic membranes in a wide spectrum of desalination and wastewater treatment applications are also elaborated. Finally, the challenges in the development of inorganic membrane for practical commercial application are identified and the future perspectives are presented.
Three-dimensional graphene oxide and polyvinyl alcohol composites as structured activated carbons for capacitive desalination Desalination (IF 5.527) Pub Date : 2017-08-18 Zhi Yi Leong, Guo Lu, Hui Ying Yang
Membrane capacitive deionization (MCDI) is a technique that is derived from conventional capacitive deionization (CDI). Additional ion-exchange membranes are included in the MCDI cell to prevent ion-expulsion and improve cyclability. As it stands, MCDI represents the most feasible option for large scale desalination to take place. In this work, we investigate the desalination performance of a novel structured activated carbon material synthesized from the assembly of polyvinyl alcohol (PVA) on graphene oxide (GO). A hydrothermal treatment causes self-assembly of the PVA covered GO sheets and the product is a polymeric framework supported by reduced GO sheets. A further activation process by KOH produces the structured activated carbon (AC). These new structured ACs possess unique morphologies and exhibit high adsorption capacities (> 30 mg g− 1) which far surpass traditional ACs.
Design and optimization of autonomous solar-wind-reverse osmosis desalination systems coupling battery and hydrogen energy storage by an improved bee algorithm Desalination (IF 5.527) Pub Date : 2017-08-25 Akbar Maleki
Most of the global population are not connected to the electrical grid and one third of these people have no access to potable water sources at the same time. Grid independent hybrid renewable energy systems (GIHRES), specifically wind and solar power, have attracted more attention to supply potable water and electricity requirements. Due to the complexity of this system, optimal balance between wind and solar resources and a convenient storage needs special attention to find a good engineering solution. In this paper for increasing the fresh water availability and to meet the load demand six GIHRES namely solar/battery or/hydrogen/reverse osmosis desalination (ROD), wind/battery or/hydrogen/ROD, and solar/wind/battery or/hydrogen/ROD are designed and modeled. For optimal design of these six systems improved bees algorithm is proposed. The results are compared with the results obtained by harmony search algorithm. From the results it is seen that the GIHRES-based battery energy storage more cost-effective than the GIHRES-based hydrogen energy storage. Also, hybridization of solar power, battery, and ROD at various maximum loss of power supply probability is the most cost-effective energy system. Moreover, the results obtained by proposed method are quite promising.
Flow conditions affecting the induction period of CaSO4 scaling on RO membranes Desalination (IF 5.527) Pub Date : 2017-08-26 Xianhui Li, David Hasson, Hilla Shemer
The extent of the induction period preceding the inception of scale formation is of major interest in the design and operation of RO desalination plants. The objective of present work was to investigate induction time phenomena related to CaSO4 scale precipitation from supersaturated solutions without or with the presence of a polycarboxylic acid based anti-scalant (AS). Membrane tests were carried out at different CaSO4 supersaturation levels (0.75–4.20) and crossflow velocities (0.1–2.5 m/s) using both tubular and spiral wound membranes. Stirred beakers tests were also conducted. Membrane induction times in the flow systems increased linearly with the increase of flow Reynolds (Re) number from 80 to 6800 both without and with AS. The induction period in the presence of the AS was higher than that observed in AS free solutions. However, the extension of the induction period induced by the AS increased markedly with the Re number. Comparison of induction times measured in membranes and stirred beaker systems revealed a critical Re number below which induction time was shorter in the membrane system and above which the induction time was longer in the membrane system compared to the beaker test.
Preparation of high-performance graphene nanoplate incorporated polyether block amide membrane and application for seawater desalination Desalination (IF 5.527) Pub Date : 2017-09-05 Filiz Ugur Nigiz
In this study, a novel graphene nanoplates (GNPs) incorporated polyether block amide (PEBA) membrane was successfully prepared to be used for seawater desalination. Pervaporative desalination performances were performed in a temperature range of 35–65 °C. Effects of GNPs content in PEBA, membrane thickness, and temperature were evaluated in terms of the flux and total salt rejection. The long-term stabilities of the membranes were experimented. Incorporating graphene nanoplate into PEBA matrix enhanced flux and ion rejections simultaneously. Experimental stability of the membrane was improved by GNPs incorporation. Graphene incorporated membranes showed excellent seawater desalination performance with the salt rejection of > 99.89% and flux of > 2.58 kg/m2·h. Based on the flux and rejection results, optimum GNPs contents in PEBA matrix were observed as 2 wt% GNPs and 3 wt% GNPs. Increasing temperatures improved the water flux and did not significantly affect the salt rejection. The highest salt rejection was obtained as 99.94% with a flux of 2.58 kg/m2·h at 35 °C when the 3 wt% GNPs incorporated membrane was used. The nanohybrid membrane preserved 99.8% of its performance during 60 h, while the rejection performance of the pristine membrane decreased to 96.8%.
Comparative performance evaluations of nanomaterials mixed polysulfone: A scale-up approach through vacuum enhanced direct contact membrane distillation for water desalination Desalination (IF 5.527) Pub Date : 2017-09-06 Mohamed S. Fahmey, Abdel-Hameed Mostafa El-Aassar, Mustafa M.Abo-Elfadel, Adel Sayed Orabi, Rasel Das
Doping of multi-walled carbon nanotube (MWCNT), silicon dioxide (SiO2), titanium dioxide (TiO2) and zinc oxide (ZnO) into polysulfone (PSf) flat sheet membranes was prepared by phase inversion process. The characterizations of the PSf and PSf-MWCNT, PSf-SiO2, PSf-TiO2 and PSf-ZnO membranes were achieved using Fourier transform infrared spectroscope, contact angle measurement, dynamic mechanical analyzer, thermo-gravimetric analysis and scanning electron microscope. Vacuum enhanced direct contact membrane distillation unit was used for evaluating the efficacy of prepared membranes in water desalination. Optimizing the operational procedures and water characteristics ensured a high slat rejection of 99.99% using the prepared membranes. The highest permeate flux obtained in the order of MWCNT (41.58) > SiO2 (38.84) > TiO2(35.6) > ZnO (34.42 L/m2·h) with optimized concentration of 1.0, 0.5, 0.75, 0.5 wt% relative to PSf weight, i.e. 15%. The optimum operational conditions included feed and permeate temperatures 60 °C and 20 °C, respectively, synthetic NaCl feed water with salinity was 10,000 ppm.
Analysis of the influence of module construction upon forward osmosis performance Desalination (IF 5.527) Pub Date : 2017-09-18 Robert W. Field, Farrukh Arsalan Siddiqui, Pancy Ang, Jun Jie Wu
The potential of a commercial forward osmosis (FO) module to recover water from NEWater brine, an RO retentate, was assessed by taking an innovative approach to obtaining the mass transfer coefficients. The performance comparison of the spiral wound (S-W) FO module with that of the flat sheet laboratory unit suggests that the winding involved in S-W construction can adversely affect performance; the values for the S-W mass transfer coefficients were half of those expected. This first-of-its-kind performance comparison utilised coupons of the membrane and spacers taken from the module. The module was used both in the conventional manner for FO and in the reverse manner with the active layer facing the draw solution. Estimates of membrane parameters and mass transfer coefficients experiments for the two orientations were obtained using pure water, 10 mM and 25 mM NaCl solution on the feed side and 1 M NaCl as draw solution. The fouling potential of NEWater brine per se was found to be low. These are the first results with a S-W module that suggest potential for this niche application; nevertheless the level of the water flux through the S-W module clearly indicates that industrial applications of S-W FO will be constrained to special cases.
Experimental quantification of the effect of intermittent operation on membrane performance of solar powered reverse osmosis desalination systems Desalination (IF 5.527) Pub Date : 2017-09-21 M. Freire-Gormaly, A.M. Bilton
Osmotic's potential: An overview of draw solutes for forward osmosis Desalination (IF 5.527) Pub Date : 2017-09-27 Daniel James Johnson, Wafa Ali Suwaileh, Abdul Wahab Mohammed, Nidal Hilal
Two-dimensional (2D) nanoporous membranes with sub-nanopores in reverse osmosis desalination: Latest developments and future directions Desalination (IF 5.527) Pub Date : 2017-09-28 Guo-Rong Xu, Jian-Mei Xu, Hui-Chao Su, Xiao-Yu Liu, Lu-Li, He-Li Zhao, Hou-Jun Feng, Rasel Das
Desalination provides an effective method to meet the worldwide freshwater crisis. Reverse osmosis (RO) based on polyamide (PA) thin-film composite (TFC) membranes have dominated desalination area with the enhancing desalting properties and decreasing energy consumption. However, it is still an urgent affair for the researchers all over the world to explore more advanced RO desalination materials and procedures to further enhance the popularization of desalination, among which development of superior membranes with as far as possible high water flux and satisfied salt rejections are particularly important. Two-dimensional (2D) nanoporous membranes with sub-nanopores, typically represented by graphene and its derivatives accompanied with some analogues such as molybdenum disulfide (MoS2), have displayed great potential and attracted vast interest in designing such kinds of desalination membranes. Actually, 2D nanoporous membranes might have opened a new era in desalination membranes fabrication and demonstrated brilliant future. Given this, in this review paper we reviewed and discussed the development of 2D nanoporous membranes with sub-nanopores on desalination with emphasis in simulations coupled with experimental studies. Besides, the feasibility and future directions of 2D nanoporous membranes are prospected. We sincerely hope that this paper could provide clues and insights for the future exploration of novel desalination membranes, and further contribute to the advance of desalination membranes synthesis and large-scale production.
Application of recoverable carbon nanotube nanofluids in solar desalination system: An experimental investigation Desalination (IF 5.527) Pub Date : 2017-09-28 Wenjing Chen, Changjun Zou, Xiaoke Li, Hao Liang
In this study, a recoverable nanofluid was prepared with brine water in an attempt to enhance the performance of solar stills. Herein, the recoverable multiwalled carbon nanotubes (MWCNTs) nanofluids which were prepared by dispersing Fe3O4 modified MWCNTs nanoparticles in saline water with high stability and recyclability. The optical properties of magnetic MWCNTs nanofluids were thoroughly investigated and showed that prepared nanofluids could successfully ameliorate the utilization rate of solar energy to provide more heat energy for saline water evaporation. Especially, for 0.04 wt% magnetic MWCNTs nanofluids, almost 100% solar energy was absorbed when the thickness of fluid exceeded 1 cm. Furthermore, the evaporation efficiencies of nanofluids were measured under the natural solar irradiation. The evaporation efficiency was obviously enhanced with the increase of magnetic MWCNTs nanofluids concentration from 24.91% (0 wt%) to 76.65% (0.04 wt%). To better understand the enhancement mechanism of nanofluids for fresh water yield, the optical-to-heat conversion in bulk liquid was synthetically investigated and a potential enhancement mechanism for evaporation process was proposed. In summary, the advantageous performance ensured the potential of recoverable-nanofluids to broaden the application prospect of solar stills.
Progress in transport theory and characterization method of Reverse Osmosis (RO) membrane in past fifty years Desalination (IF 5.527) Pub Date : 2017-09-30 Ahmad Fauzi Ismail, Takeshi Matsuura
In this paper an attempt is made to review the progress in membrane characterization and transport theory in historical perspective. Its central theme is the membrane “pore” around which progress has been revolving, irrespective of whether the researcher is “for” or “against” the existence of pores at the top dense layer of the RO membrane. The article starts from nineteen-fifties when the development of cellulose acetate membrane was launched on the basis of the Preferential Sorption-Capillary Flow (PS-CF) mechanism. The Sorption-Diffusion (S-D) model, which was presented at almost the same time, regards the top surface layer dense and homogeneous. No heterogeneity is allowed and the presence of pores makes the RO membrane imperfect, causing the leakage of salt. Thus, the PS-CF model came to direct confrontation with the S-D model. It is shown in this brief historic review how the advanced characterization instrument has revealed the heterogeneous structure of the top surface of the RO membrane and measured its “pore size” and “pore size distribution”. The advanced transport theory based on Molecular Dynamics (MD) simulation also resulted in the presence of the multi-modal pore size distribution.
Molecular dynamics modeling of nano-porous centrifuge for reverse osmosis desalination Desalination (IF 5.527) Pub Date : 2017-10-09 Tiange Li, Qingsong Tu, Shaofan Li
A concept of the porous graphene membrane centrifuge is proposed aiming at fabrication of large scale, fouling-free desalination machine with nanomaterial-based reverse osmosis modules. The concept as well as strategy of such porous rotating graphene membrane device is approved through molecular dynamics (MD) modeling and simulation of a nano-fluidic device that in order to make a quantitative evaluation. First, an analytical formulation is derived for the critical angular velocity above which the centrifugal force is able to counter-balance osmosis pressure, so that the reverse osmosis (RO) desalination process can proceed. The critical angular velocity derived from this formulation is compared with MD simulated critical angular velocity. Based on MD simulation results, it is shown that the rotating porous membrane device may significantly improve desalination efficiency by combining the centrifugal separation and and the selectivity of porous graphene membrane to achieve reverse-osmosis desalination. Furthermore, we have shown that the proposed desalination device has an intrinsic anti-fouling mechanism, and then we have studied the effect of pore size on the flux rate by conducting simulations with the applied rotating speed. Moreover, we have conducted energy and efficiency analysis for the proposed desalination device model, and we obtained the relationship between fresh water flux rate and the angular velocity, at the same time, with the pore size. By choosing the most efficient angular velocity and the pore size that ensures salt rejection, an optimal nano-fluidic device design is achieved.
Factors influencing the performance and productivity of solar stills - A review Desalination (IF 5.527) Pub Date : 2017-10-10 Karthikeyan Selvaraj, Alagumurthi Natarajan
Water scarcity is a major threat for future as the fresh water resources are being exploited and polluted rapidly by mankind. Hence, converting the brackish, saline water in to pure water is one of the viable solutions to overcome the demand for water. Desalination using solar still is simple among various techniques available for removal of salinity. The limitation being its productivity, researchers have consistently attempted to improve the performance of solar stills. This article reviews various factors that influence the performance of the solar still like solar radiation intensity, temperature difference, collector area, basin water depth, insulation, angle of inclination, thickness of glass cover plate, wind velocity and a few methods for improving the quantity of distillate produced. Such a review would benefit the knowledge society for further research and development of a solar still to make it an economically viable option.
In situ modification of membrane elements for improved boron rejection in RO desalination Desalination (IF 5.527) Pub Date : 2017-10-12 Shiran Shultz, Viatcheslav Freger
The study presents in situ modification of a spiral-wound seawater reverse osmosis (SWRO) membrane elements using sorption of hydrophobic long-chain aliphatic amine molecules as a generic approach to increasing selectivity, in particular, boron removal. Spiral-wound seawater SW30 elements modified using decylamine and dodecylamine showed 2–4 times lower boron passage for the modified elements at the expense of a moderate drop in permeability. Autopsy indicated no change in surface morphology and chemistry, suggesting immobilization of the modifying molecules within the active layer. Overall, the reported in situ modification of the SWRO element resulted in a superior trade-off between permeability and boron passage and no change in salt rejection, as compared to regular polyamide membranes. The enhanced selectivity toward boron5 removal could potentially help eliminate or reduce the costs related to the second pass in sea water desalination.
Diffusion behaviour of multivalent ions at low pH through a MFI-type zeolite membrane Desalination (IF 5.527) Pub Date : 2017-10-21 Bo Zhu, Gayle Morris, Il-Shik Moon, Stephen Gray, Mikel Duke
Energy use for membrane seawater desalination – current status and trends Desalination (IF 5.527) Pub Date : 2017-10-24 Nikolay Voutchkov
Technological advances of membrane seawater desalination have propelled its worldwide use. Despite the two-fold reduction of its power demand over the past 20 years, seawater desalination remains the most energy intensive alternative for production of fresh drinking water at present. This article provides an overview of the current status of energy use for seawater desalination, discusses the minimum energy demand for production of fresh water and presents key factors that influence the desalination plant energy demand for the site specific conditions of a given desalination project. The article describes key benefits and challenges associated with the implementation of energy-saving technologies and equipment such as: collocation of desalination and power plants; alternative RO system configurations proven to yield significant energy savings such as; low-recovery plant design; use of split permeate two-pass RO system configuration; three-center RO system design; and use of high productivity/low energy membrane elements, hybrid RO membrane vessel configurations, large-size high efficiency pumps and pressure-exchanger based energy recovery systems. The article also discusses emerging desalination technologies with high-energy reduction potential and provides a forecast of the potential impact of future technologies on energy use for membrane desalination.
Grid-tied and stand-alone hybrid solar power system for desalination plant Desalination (IF 5.527) Pub Date : 2017-10-31 Chaouki Ghenai, Adel Merabet, Tareq Salameh, Erola Colon Pigem
This paper presents results on simulation, optimization and control of hybrid solar based energy system to power a desalination plant. The principal objective is to design a clean energy system to meet the desired electric load of the desalination plant with high renewable fraction, low cost of energy, and low carbon dioxide gas emissions. Hourly simulations and optimization were performed to determine the performance and life cycle cost of the different hybrid power configurations. The results of the baseline or the actual power system from the grid are compared with two new renewable power systems: (1) grid tied solar system: solar PV/grid/inverter power system, and (2) Off grid solar power system: PV/diesel generator/battery/inverter power system. The results show that the solar PV/grid/inverter power system offers the best performance compared to PV/diesel generator/battery/inverter. The total energy from the hybrid grid tied solar system is used to meet the AC load of the desalination plant with almost no excess electricity and power shortage. The proposed hybrid power system for the desalination plant is sustainable, economically viable and environmentally friendly: high renewable fraction (47.3%), low excess power (0.15%), low levelized cost of energy (90 $/MWh), and low CO2 gas emissions (264.25 kg CO2/MWh).
Membranes and processes for forward osmosis-based desalination: Recent advances and future prospects Desalination (IF 5.527) Pub Date : 2017-11-02 Yi-Ning Wang, Kunli Goh, Xuesong Li, Laurentia Setiawan, Rong Wang
Forward osmosis (FO) is an increasingly important technology that has been deemed promising for addressing the global issue of water scarcity. Rapid progress over the past decade has been marked by significant innovations in the membrane development and process design. The key idea is to develop next-generation membranes through advanced membrane fabrication methods as well as hybrid systems where the FO process can really value-add. As such, this article provides an overview of the various FO membrane designs, in particular, the thin-film composite, surface-modified, and mixed matrix and biomimetic membranes. The pros and cons of each type of membranes are discussed together with the strategies used to optimize membrane properties such as structural parameter (S), water permeability (A) and salt permeability (B) to achieve enhanced FO performances. Furthermore, we also discuss the roles of FO in the various hybrid systems and evaluate the potential of these hybrid systems for desalination. Lastly, we provide our perspectives, especially in the area of membrane fabrications and FO hybrid systems, to shed light on the future research directions for harnessing the true potential of FO for desalination.
Effect of operational conditions on post-treatment of RO permeate of geothermal water by using electrodeionization (EDI) method Desalination (IF 5.527) Pub Date : 2017-11-02 Samuel Bunani, Müşerref Arda, Nalan Kabay
With the growing of electronics, semiconductors, food and pharmaceutical manufactures, the need of water quantity with high purity is increasing. The water quality needed should be with high electrical resistance and free of weakly ionized dissolved species. Integration of separation processes such as reverse osmosis (RO) and electrodeionization (EDI) was proven to be successful to produce water with high quality. This paper is about the applicability of EDI method for post-treatment of RO permeate of geothermal water. For this purpose, the effects of process parameters such as feed flow rate, electrical potential applied, type of ion exchange membranes, and cell number on reduction of electrical conductivity and the contents of boron, silicon and arsenic in EDI product water were investigated. In addition, pseudo first order and pseudo second order kinetics models, infinitive solution volume (ISV) and unreacted core (UCM) models were applied to determine the rate controlling steps of the removal of electrical conductivity and boron by EDI process. Obtained results revealed that a EDI product water containing ˂0.20 mg B/L, ˂0.05 mg Si/L and ˂0.10 μg As/L was produced using a multi-cell EDI in which ion exchange resins in mixed bed configuration is placed between Neosepta CMX-AMX ion exchange membrane pair. These results were obtained when the optimum flow rate of 1.08 L/h and electrical potential of 20 V were applied to multi-cell EDI. At the optimal operational conditions, boron removal was found to be governed by second order kinetic model and the determining steps were film diffusion and liquid film according to ISV and UCM models, respectively. It was observed that thick ion exchange membranes were better than thin ion exchange membranes for polishing RO permeate of geothermal water by using EDI process.
Effect of oxidation with coagulation and ceramic microfiltration pre-treatment on reverse osmosis for desalination of recycled wastewater Desalination (IF 5.527) Pub Date : 2017-11-06 D.T. Myat, F. Roddick, P. Puspita, L. Skillman, J. Charrois, I. Kristiana, W. Uhl, E. Vasyukova, G. Roeszler, A. Chan, B. Zhu, S. Muthukumaran, S. Gray, M. Duke
Can a hybrid RO-Freeze process lead to sustainable water supplies? Desalination (IF 5.527) Pub Date : 2017-11-09 Mansour Ahmad, Darren L. Oatley-Radcliffe, Paul M. Williams
In this paper we investigate the potential for using suspension crystallisation for the production of clean drinking water from a seawater source. The experimental results show that the produced water from the suspension crystallisation plant not only meets water quality standards but is comparable in ionic composition to premier bottled water from around the globe. The experimental results obtained from a pilot scale suspension crystallisation unit showed that the achievable water recovery was around 41% and the salt rejection ratio reached over 99%, which is comparable with most desalination technologies. Moreover, a hybrid RO-Freeze plant has been proposed that is capable of significantly increasing the potable product water that could be achieved by RO alone (~ 400% increase), while simultaneously concentrating the RO brine (used as feed water) producing a super brine of ~ 13 wt%. While there is a cost to this additional process in terms of capital and energy that must be quantified, the obvious increase in water harvest and reduction in residual brine quantity lead to a very attractive desalination process. If the energy demands are acceptable, then this technology could lead to a more sustainable water future.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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