Showing papers in "Desalination in 2013"
TL;DR: In this paper, the authors present a cost analysis of the reverse osmosis process and the main parameters influencing the total water cost produced by different desalination technologies, including capital and operating costs, as well as local incentives or subsidies.
Abstract: Desalination capacity has rapidly increased in the last decade because of the increase in water demand and a significant reduction in desalination cost as a result of significant technological advances, especially in the reverse osmosis process. The cost of desalinated seawater has fallen below US$0.50/m 3 for a large scale seawater reverse osmosis plant at a specific location and conditions while in other locations the cost is 50% higher (US$1.00/m 3 ) for a similar facility. In addition to capital and operating costs, other parameters such as local incentives or subsidies may also contribute to the large difference in desalted water cost between regions and facilities. Plant suppliers and consultants have their own cost calculation methodologies, but they are confidential and provide water costs with different accuracies. The few existing costing methodologies and software packages such as WTCost© and DEEP provide an estimated cost with different accuracies and their applications are limited to specific conditions. Most of the available cost estimation tools are of the black box type, which provide few details concerning the parameters and methodologies applied for local conditions. Many desalination plants built recently have greater desalinated water delivery costs caused by special circumstances, such as plant remediation or upgrades, local variation in energy costs, and site-specific issues in raw materials costs (e.g., tariffs and transportation). Therefore, the availability of a more transparent and unique methodology for estimating the cost will help in selecting an appropriate desalination technology suitable for specific locations with consideration of all the parameters influencing the cost. A techno-economic evaluation and review of the costing aspects and the main parameters influencing the total water cost produced by different desalination technologies are herein presented in detail. Some recent developments, such as the increase of unit capacity, improvements in process design and materials, and the use of hybrid systems have contributed to cost reduction as well as reduction in energy consumption. The development of new and emerging low-energy desalination technologies, such as adsorption desalination, will have an impact on cost variation estimation in the future.
TL;DR: The incorporation of nanoparticles into polymeric membranes has been the trend in the field of membrane research recently as discussed by the authors, and nanoparticles could produce synergistic effects when incorporated with different types of materials.
Abstract: Synthetic membranes have become the focus of separation processes in different industries. Synthetic membranes may be composed of inorganic materials (such as ceramics) and organic materials (such as polymers). Current research on membranes focus more on polymeric membranes due to better control of the pore forming mechanism, higher flexibility, smaller spaces required for installation and lower costs compared to inorganic membranes. Though polymeric membranes have these properties which make them better materials in membrane fabrication, they also have some disadvantages which need to be overcome. Common problems faced by polymeric membranes, such as high hydrophobicity, exposure to biofouling, low fluxes and low mechanical strength have become the focus of researchers in order to improve these disadvantages. The incorporation of nanoparticles into polymeric membranes has been the trend in the field of membrane research recently. Incorporation of nano-sized materials could produce synergistic effects when incorporated with different types of materials. This paper discusses a few types of nanoparticles incorporated into various types of polymeric membranes. Nanoparticles that will be discussed include silver, iron, zirconium, silica, aluminium, titanium, and magnesium based nanoparticles. Nanoparticles affect the permeability, selectivity, hydrophilicity, conductivity, mechanical strength, thermal stability, and the antiviral and antibacterial properties of the polymeric membranes. Though nanoparticles usually improve the performances of the membranes, they also might change or even deteriorate the performances of the membranes. Thus, careful study needs to be done in order to choose the most appropriate types and composition of nanoparticles to be incorporated into polymeric membranes.
TL;DR: In this paper, a review of polymeric membrane fabrication techniques for pressure driven membrane processes and membrane distillation is discussed, the fabrication technique, properties of the fabricated membranes and performance in water desalination are related.
Abstract: In this review, polymeric membrane fabrication techniques for pressure driven membrane processes and membrane distillation are discussed. The fabrication technique, properties of the fabricated membranes and performance in water desalination are related. Important parameters which affect the membrane performance such as crystallinity of the membrane based polymer, porous structure, hydrophobicity/hydrophilicity, membrane charge and surface roughness are analyzed. Despite the fact that extensive knowledge exist on how to ‘tailor’ membrane pore structure including its surface properties and cross-section morphology by selection of appropriate fabrication methods, there is still a challenge to produce reliable membranes with anti-fouling properties, chemical resistance, high mechanical strength with high flux and selectivity. To ensure progress in membrane performance, further improvements are needed of common membrane fabrication techniques such as phase inversion and interfacial polymerization. At the same time, the potential of novel fabrication techniques such as electrospinning and track-etching needs to be assessed. A comprehensive understanding between structure-surface properties and performance is a key for further development and progress in membrane technology for water desalination.
TL;DR: In the last years, anaerobic membrane bioreactor (AnMBR) technology is being considered as a very appealing alternative for wastewater treatment due to the significant advantages over conventional anaerobobic treatment and aerobic membrane bioresistability as mentioned in this paper.
Abstract: In the last years, anaerobic membrane bioreactor (AnMBR) technology is being considered as a very appealing alternative for wastewater treatment due to the significant advantages over conventional anaerobic treatment and aerobic membrane bioreactor (MBR) technology Many articles have touted the diverse potential applications of AnMBR in various stream treatment, and membrane fouling issues In current review, the fundamentals of AnMBR (including advantages and configurations, membrane materials and modules, and history development), application development in various stream treatment, and membrane fouling researches are summarized and critically assessed The characteristics of AnMBR and aerobic MBR for wastewater treatment are also compared AnMBR technology appears to be suitable for treatment of various streams, especially for food industrial wastewater and municipal wastewater AnMBR treatment usually encounters more serious membrane fouling problem This, however, can be remedied through various conventional and novel membrane fouling control or cleaning measures Based on the review, future research perspectives relating to its application and membrane fouling research are proposed
TL;DR: Graphene oxide (GO) dispersed polysulfone (PSf) mixed matrix membranes were prepared by wet phase inversion method in this paper, where the morphology of membranes was studied using scanning electron microscope (SEM) images.
Abstract: Graphene oxide (GO) dispersed polysulfone (PSf) mixed matrix membranes were prepared by wet phase inversion method. The morphology of membranes was studied using scanning electron microscope (SEM) images. The variation in hydrophilicity was studied by measuring surface wettability and water swelling experiments. The performance of membranes in terms of pure water flux and salt rejection was studied. SEM images depict enhanced macrovoids, while the contact angle data reveals that, GO incorporated membrane surface is moderately hydrophilic. Membranes exhibited improved salt rejection after GO doping. Membrane with 2000 ppm GO loading has exhibited maximum of 72% Na2SO4 rejection at 4 bar applied pressure. The salt rejection seems to depend on pH of the feed solution and it has been witnessed that the salt rejection showed an increasing trend with increase in the pH.
TL;DR: In this paper, the authors describe the rejection of heavy metal ions using a commercial nanofiltration membrane (NF270) and explore the effect of feed pH, pressure and metal concentration on the metal rejections and permeate flux and in some cases permeate pH was explored.
Abstract: This study describes the rejection of heavy metal ions using a commercial nanofiltration membrane (NF270). The effect of feed pH, pressure and metal concentration on the metal rejections and permeate flux and in some cases permeate pH was explored. The results showed that with all metals examined (except As (III)), when the feed pH is below the isoelectric point, the rejection increased. NF270 rejected almost 100% of copper ions at low concentrations, but decreased to 58% at the highest concentration examined. Using 1000 mg/L concentration level, pH = 1.5 ± 0.2 and 4 bar the rejection was 99%, 89% and 74% for cadmium, manganese and lead respectively. However at pH above the isoelectric point the average rejections decreased. NF270 was unable to retain As(III). The metals caused a flux decline due to membrane fouling in the order of severity: Cu 2+ > Cd 2+ ≈ Mn 2+ > Pb 2+ ≈ As 3+ . The correlation between adsorbed amounts of the metals onto NF270 with the normalised flux shows that as the amount increased the normalised flux decreased, except for arsenic that had a higher deposited amount and higher flux. The RMS roughness as obtained by AFM showed that roughness was decreased by membrane fouling.
TL;DR: In this article, the authors present a standard methodology for testing of ODMP membranes based on experience gained and operating conditions used in forward osmosis (FO) and pressure-retarded osmo-sis (PRO) studies.
Abstract: article i nfo Osmotically driven membrane processes (ODMPs) such as forward osmosis (FO) and pressure retarded osmo- sis (PRO) are extensively investigated for utilization in a broad range of applications. In ODMPs, the operating conditions and membrane properties play more critical roles in mass transport and process performance than in pressure-driven membrane processes. Search of the literature reveals that ODMP membranes, especially newly developed ones, are tested under different temperatures, draw solution compositions and concentra- tions, flow rates, and pressures. In order to compare different membranes, it is important to develop standard protocols for testing of membranes for ODMPs. In this article we present a standard methodology for testing of ODMP membranes based on experience gained and operating conditions used in FO and PRO studies in recent years. A round-robin testing of two commercial membranes in seven independent laboratories revealed that water flux and membrane permeability coefficients were similar when participants performed the experi- ments and calculations using the same protocols. The thin film composite polyamide membrane exhibited higher water and salt permeability than the asymmetric cellulose-based membrane, but results with the high permeability thin-film composite membrane were more scattered. While salt rejection results in RO mode were relatively similar, salt permeability coefficients for both membranes in FO mode were more varied. Results suggest that high permeability ODMP membranes should be tested at lower hydraulic pressure in RO mode and that RO testing be conducted with the same membrane sample used for testing in FO mode.
TL;DR: An NH3/CO2 forward osmosis (FO) membrane brine concentrator (MBC) pilot was tested in the desalination of frac flowback and produced waters from natural gas extraction operations in the Marcellus shale region as mentioned in this paper.
Abstract: An NH3/CO2 forward osmosis (FO) membrane brine concentrator (MBC) pilot was tested in the desalination of frac flowback and produced waters from natural gas extraction operations in the Marcellus shale region. The average concentration of these waters was 73,000 ± 4200 mg/L total dissolved solids (TDS), with an average hardness of 17,000 ± 3000 mg/L as CaCO3. Pretreatment included chemical softening, media filtration, activated carbon, and cartridge filtration. Average pilot performance characteristics were: system recovery of 64 ± 2.2%, nominal water flux of 2.6 ± 0.12 L/m2-h, concentrated brine concentration of 180,000 ± 19,000 mg/L TDS, and product water with 300 ± 115 mg/L TDS. The thermal energy required by the FO MBC pilot, when operated within the efficient flow specification of the draw solution recycling system, averaged 275 ± 12 kWhth/m3 of product water, approximately 57% less thermal energy input than that estimated for a conventional evaporator operated in a comparable single stage, non-mechanical vapor compression (MVC) configuration. In an MVC configuration, which uses electrical rather than thermal energy, modeling indicates that the FO MBC process will require 42% less electrical energy than a conventional forced circulation MVC evaporator.
TL;DR: In this article, the main features of membrane distillation along with its basic principles are presented and the efforts of researchers in coupling MD with solar energy and their cost estimates are reviewed as well.
Abstract: Membrane distillation (MD) is a hybrid membrane-evaporative process which has been of interest for desalination. MD requires two types of energy, namely, low temperature heat and electricity. Solar collectors and PV panels are mature technologies which could be coupled to MD process. The interest of using solar powered membrane distillation (SPMD) systems for desalination is growing worldwide due to the MD attractive features. Small scale SPMD units suitable to provide water for human needs in remote areas where water and electricity infrastructures are currently lacking have been developed and tested by a number of researchers. The combination of solar energy with MD has proven technically feasible; however, the cost of produced water is relatively high compared with that produced from the commercial PV–RO process. The production of commercial, reliable, low cost and long lasting MD modules will put this process on the front edge of desalination technologies. The aim of this article is to present the main features of MD along with its basic principles. Efforts of researchers in coupling MD with solar energy and their cost estimates are reviewed as well.
TL;DR: To produce large volumes of newly discovered unconventional gas, hydraulic fracturing of wells is commonly practiced in basins where shale gas and coal bed methane are extracted as mentioned in this paper, which successfully removing fouling and restoring water flux.
Abstract: To produce large volumes of newly discovered unconventional gas, hydraulic fracturing of wells is commonly practiced in basins where shale gas and coal bed methane are extracted. Hydraulic fracturing of wells during oil and gas (OG successfully removing fouling and restoring water flux.
TL;DR: In this article, the authors investigated the energy consumption of MCDI, and the fraction of energy that can be recovered during the ion desorption step of the MCDi, as a function of influent concentration, water flow rate and water recovery.
Abstract: Membrane capacitive deionization (MCDI) is a non-faradaic, capacitive technique for desalinating brackish water by adsorbing ions in charged porous electrodes To compete with reverse osmosis, the specific energy consumption of MCDI needs to be reduced to less than 1 kWh per m 3 of freshwater produced In order to investigate the energy consumption of MCDI, we present here the energy consumption, and the fraction of energy that can be recovered during the ion desorption step of MCDI, as a function of influent concentration, water flow rate and water recovery Furthermore, the energy consumption of MCDI based on experimental data of our lab-scale system is compared with literature data of reverse osmosis Comparing with literature data for energy consumption in reverse osmosis, we find that for feed water with salinity lower than 60 mM, to obtain freshwater of ~ 1 g TDS/L, MCDI can be more energy efficient
TL;DR: An overview of the properties of aquaporins, their preparation and characterization and the challenges in exploiting the remarkable properties are discussed, and various attempts to construct aquaporin in membranes for desalination are presented.
Abstract: Based on their unique combination of offering high water permeability and high solute rejection aquaporin proteins have attracted considerable interest over the last years as functional building blocks of biomimetic membranes for water desalination and reuse. The purpose of this review is to provide an overview of the properties of aquaporins, their preparation and characterization. We discuss the challenges in exploiting the remarkable properties of aquaporin proteins for membrane separation processes and we present various attempts to construct aquaporin in membranes for desalination; including an overview of our own recent developments in aquaporin-based membranes. Finally we outline future prospects of aquaporin based biomimetic membrane for desalination and water reuse.
TL;DR: In this article, the authors present an overview of most studies carried out on these issues and some useful equations and information in this context are reported and compare to other separation processes used in desalination.
Abstract: The non-isothermal membrane distillation (MD) separation process is known for about 50 years and very few studies are reported on its economics, energy analysis and costs evaluations. Dispersed and confusing water production costs (WPC) and specific energy consumption (EC) analysis were reported. Most of them are simulated and others are based on various costs assumptions. At present, the common asked questions about the published papers in MD including EC and WPC are: how these reported calculations on WPC and EC were made?, what is the current WPC of MD?, and how WPC of MD can be improved?. An overview of most studies carried out on these issues is presented and some useful equations and information in this context are reported. Comparison to other separation processes used in desalination is made. At present, the main challenge for large-scale MD is EC and WPC. New directions on MD should be raised. More rigorous investigations and focused directions on economical analysis of MD systems should be conducted. A unified standard method for analysis and calculations should be followed to determine WPC. For the benefit of MD process, one should be cautious when reporting simulated, non-realistic and non-contrasted WPC.
TL;DR: In this article, an adaption desalination (AD) cycle with low-temperature waste heat, which is available in abundance from either the renewable energy sources or exhaust of industrial processes, is described.
Abstract: Desalination, other than the natural water cycle, is hailed as the panacea to alleviate the problems of fresh water shortage in many water stressed countries. However, the main drawback of conventional desalination methods is that they are energy intensive. In many instances, they consumed electricity, chemicals for pre- and post-treatment of water. For each kWh of energy consumed, there is an unavoidable emission of Carbon Dioxide (CO 2 ) at the power stations as well as the discharge of chemically-laden brine into the environment. Thus, there is a motivation to find new direction or methods of desalination that consumed less chemicals, thermal energy and electricity. This paper describes an emerging and yet low cost method of desalination that employs only low-temperature waste heat, which is available in abundance from either the renewable energy sources or exhaust of industrial processes. With only one heat input, the Adsorption Desalination (AD) cycle produces two useful effects, i.e., high grade potable water and cooling. In this article, a brief literature review, the theoretical framework for adsorption thermodynamics, a lumped-parameter model and the experimental tests for a wide range of operational conditions on the basic and the hybrid AD cycles are discussed. Predictions from the model are validated with measured performances from two pilot plants, i.e., a basic AD and the advanced AD cycles. The energetic efficiency of AD cycles has been compared against the conventional desalination methods. Owing to the unique features of AD cycle, i.e., the simultaneous production of dual useful effects, it is proposed that the life cycle cost (LCC) of AD is evaluated against the LCC of combined machines that are needed to deliver the same quantities of useful effects using a unified unit of $/MWh. In closing, an ideal desalination system with zero emission of CO 2 is presented where geo-thermal heat is employed for powering a temperature-cascaded cogeneration plant.
TL;DR: In this article, the electrosorption selectivity of cations can be determined by the ionic charge, hydrated radius, and initial molar concentration, which can be further enhanced by increasing the applied voltage.
Abstract: This study has been focused on an experimental investigation of the electrosorption selectivity for alkali- and alkaline-earth cations in activated carbon-based capacitive deionization process. Cyclic voltammetry experiments showed that a large proportion of micropores in activated carbon electrodes were associated with electrical double-layer overlapping, and the specific capacitance of cations increased with the decrease of hydrated radius. A series of electrosorption experiments were conducted to identify the preferential electrosorption in multi-ionic solutions. The electrosorption selectivity of cations can be determined by the ionic charge, hydrated radius, and initial molar concentration. The activated carbon electrodes presented greater selectivity of smaller ions over larger ions due to size-affinity, while divalent cations possessing higher valence to screen the surface charge were more effectively removed than monovalent cations. The increase of initial molar concentration resulted in the increase of electrosorption capacity. Moreover, the ion selectivity can be further enhanced by increasing the applied voltage. The results are relevant to water desalination and softening in electrosorption.
TL;DR: A review of the state of the art in MDC design and performance, safety issues related to the use of MDCs with wastewater, and areas that need to be examined to achieve practical application of this new technology can be found in this paper.
Abstract: Microbial desalination cells (MDCs) are a new, energy-sustainable method for using organic matter in wastewater as the energy source for desalination. The electric potential gradient created by exoelectrogenic bacteria desalinates water by driving ion transport through a series of ion-exchange membranes (IEMs). The specific MDC architecture and current conditions substantially affect the amount of wastewater needed to desalinate water. Other baseline conditions have varied among studies making comparisons of the effectiveness of different designs problematic. The extent of desalination is affected by water transport through IEMs by both osmosis and electroosmosis. Various methods have been used, such as electrolyte recirculation, to avoid low pH that can inhibit exoelectrogenic activity. The highest current density in an MDC to date is 8.4 A/m2, which is lower than that produced in other bioelectrochemical systems. This implies that there is a room for substantial improvement in desalination rates and overall performance. We review here the state of the art in MDC design and performance, safety issues related to the use of MDCs with wastewater, and areas that need to be examined to achieve practical application of this new technology.
TL;DR: In this paper, a thin-film nanocomposite (TFN) nanofiltration membrane has been developed via interfacial incorporation of aminosilanized TiO2 nanoparticles.
Abstract: A novel thin-film nanocomposite (TFN) nanofiltration membrane has been developed via interfacial incorporation of aminosilanized TiO2 nanoparticles Polyethersulfone (PES) barrier coating on a porous α-Al2O3 ceramic hollow fibre membrane was employed as the substrate layer TiO2 nanoparticles were incorporated in pure and functionalized forms into trimesoyl chloride (TMC) organic phase and m-phenylenediamine (m-PDA) aqueous phase, respectively The surface functionalization of TiO2 nanoparticle was confirmed by XRD, FTIR and UV-vis reflectance spectral analysis Surface properties of the fabricated composite membranes were investigated using SEM, EDX, AFM and contact angle goniometry Heat resistibility of polyamide layers were examined using thermo-gravimetric analysis (TGA) Membranes intrinsic properties such as: the permeability, selectivity and pore size determination were also elucidated The silane coupling agent containing amino-functional groups reinforced TiO2 nano fillers for the good dispersion inside the polyamide skin layer by reducing their surface energy At ultra-low concentration (0005 wt%), the functionalized TiO2 nanoparticles improved the salt rejection to 54% as well as water flux to 123 l/m2 h By incorporating a higher concentration of TiO2 nanoparticles, water flux was increased up to 2-fold compared with the pure polyamide membrane with negligible rejection loss These results demonstrated competency of using functionalized inorganic nanoparticles to increase the product flux and the separation efficiency
TL;DR: In this paper, the authors studied the separation of lithium from salt lake brines by NF and LPRO and obtained a total separation between Li+ and Na+ with a diffusion flux (4.42 10−−7−mol).
Abstract: The aim of the present work is to study the separation of lithium from salt lake brines by NF and LPRO. NF90 membrane compared to the XLE a LPRO membrane appeared more efficient for Li+ extraction due to its higher hydraulic permeability to pure water and 0.1 M NaCl solution, its lower critical pressure (Pc = 0), its higher selectivity between monovalent ions (40%) obtained at low operating transmembrane pressure (below 15 bar) and its lower average roughness (105 ± 10 nm) decreasing the propensity to be fouled. NF90 exhibited 100% rejection of magnesium in the first step separation from brine diluted ten times as 15% for Li+, with a final separation of 85% between Mg2 +/Li+. The permeability to the diluted brine is 0.7 L.h− 1.m− 2.bar− 1 usable to size full scale experiments, but the fouling mechanism has to be discovered in the future work. In a second step we have not succeeded to separate totally Li+ and Na+ in the permeate obtained before (15% of separation only between Li+ and Na+). To solve this problem, we did dialysis. We obtained a total separation between Li+ and Na+ with a diffusion flux (4.42 10− 7 mol.s− 1.m− 2 at 20 °C) for NaCl 0.1 M 5 times higher for NF90 vs XLE.
TL;DR: In this article, the authors provide an in-depth insight on the utilization of CNTs to heighten the performance of the available seawater and brackish water desalination in a holistic manner.
Abstract: The fast-evolving world of nanotechnology captivates researchers in the state-of-the-art water desalination technologies. Rapid development and advancement have been reflected by a drastically increasing number of scientific investigation on the manipulation of nanomaterials in various desalination technologies. With demand rising in worldwide, the revolution of desalination technology using CNT materials to mitigate few raised over concerns, particularly energy issues, seems a viable option. In this context, this review article intends to provide an in-depth insight on the utilization of CNTs to heighten the performance of the available seawater and brackish water desalination in a holistic manner. The transport properties and chemical functionalities of this novel material to potentially facilitate excellent flux of water transport and salt rejection are outlined. Based on the computational and experimental work done over the past decade, a detailed description on the current knowledge relevant to the exploitation of CNTs in desalination has been highlighted. The current hurdles and future challenges related to this technology are then addressed. With novel properties come new opportunities for technological and commercial development. The applications of CNTs in desalination have been demonstrated and it is anticipated that applying CNTs in desalination holds very promising future prospects and will therefore lead the future direction of the realm.
TL;DR: In this article, the state-of-the-art developments and breakthrough in the surface modified and nanoparticles incorporated polyamide thin film composite (PA-TFC) reverse osmosis (RO) membranes are focused and summarized combining with the prospects.
Abstract: Polyamide thin film composite (PA-TFC) membranes are becoming more and more widely used for water desalination both in industrial and experimental plants due to their superior properties. However, trade-off between the permeability and the salt rejections, fouling and chlorination are seriously restricting their better operational functions. Therefore, various strategies have been explored to tackle these problems, among which surface modifications (e.g., surface coating) and nanoparticles incorporations have been identified to be the most effective ones. Thus, in this review, the state-of-the-art developments and breakthrough in the surface modified and nanoparticles incorporated PA-TFC reverse osmosis (RO) membranes are focused and summarized combining with the prospects. This review provides comprehensive information and gives an outlook on the surface modifications and nanoparticles incorporations, which might supply some clues to explore more advanced and innovative strategies for improving the performance of the PA-TFC RO membranes.
TL;DR: In this article, the feasibility of using Membrane Distillation (MD) technology to desalinate brines from thermal desalination plants was evaluated and the performance of different MD membranes was compared under various operating conditions using synthetic saline solutions and seawater from the Arabian Gulf.
Abstract: Membrane Distillation (MD) is a hybrid thermal-membrane process that can use low grade waste heat to generate a vapor pressure difference across a hydrophobic membrane to produce a high quality distillate from concentrated brines. The MD process presents several benefits compared to Reverse Osmosis (RO) including: superior product water quality; ability to treat high salinity brines, and potentially lower capital & operating costs. These unique features of the MD process make it an ideal technical solution to desalinate brines from thermal desalination plants to increase fresh water production in the Arabian Gulf region. This paper evaluated the feasibility of using MD technology to desalinate brines from thermal desalination plants. A state-of-the-art MD bench scale unit was built and the performance of different MD membranes was compared under various operating conditions using synthetic saline solutions, brine from a thermal desalination plant and seawater from the Arabian Gulf. Overall, MD was shown to be a feasible and effective process capable of consistently producing high quality distillate (conductivity
TL;DR: In this article, a review of the information on methods for boron removal and its development is presented, showing the direction of its development and providing promising features for technological approach.
Abstract: The manuscript gathers knowledge on boron — its properties, sources, presence in the environment, effects on plants and animals and methods for its removal. It is shown that so far used recovery technologies should be developed and there is still a room for new separation methods. It seems that introduction of new sorption materials as well as the use of sorption–membrane filtration hybrid, combining sorption on fine B-sensitive sorbent with membrane separation, can offer promising features for technological approach. The intention of this review is to update the information on methods for boron removal and to show the direction of its development.
TL;DR: The economics of membrane distillation and common seawater desalination methods including multi effect distillation (MED), multistage flash (MSF) and reverse osmosis (RO) are compared in this paper.
Abstract: The economics of membrane distillation (MD) and common seawater desalination methods including multi effect distillation (MED), multistage flash (MSF) and reverse osmosis (RO) are compared. MD also has the opportunity to enhance RO recovery, demonstrated experimentally on RO concentrate from groundwater. MD concentrated RO brine to 361,000 mg/L total dissolved solids, an order of magnitude more saline than typical seawater, validating this potential. On a reference 30,000 m3/day plant, MD has similar economics with other thermal desalination techniques, but RO is more cost effective. With the inclusion of a carbon tax of $23 per tonne carbon in Australia, RO remained the economically favourable process. However, when heat comes at a cost equivalent of 10% of the value of the steam needed for MD and MED, under a carbon tax regime, the cost of MD reduces to $0.66/m3 which is cheaper than RO and MED. The favour to MD was due to lower material cost. On low thermally, high electrically efficient installations MD can desalinate water from low temperature (
TL;DR: In this article, switchable polarity solvents (SPS), mixtures of carbon dioxide, water, and tertiary amines, are presented as viable forward osmosis (FO) draw solutes allowing a novel SPS FO process.
Abstract: Switchable polarity solvents (SPS), mixtures of carbon dioxide, water, and tertiary amines, are presented as viable forward osmosis (FO) draw solutes allowing a novel SPS FO process. In this study substantial osmotic strengths of SPS are measured with freezing point osmometry and were demonstrated to induce competitive fluxes at high salt concentrations on a laboratory-scale FO unit utilizing a flat sheet cellulose triacetate (CTA) membrane. Under the experimental conditions the SPS degrades the CTA membrane; however experiments with polyamide reverse osmosis (RO) membranes display stability towards SPS. Once the draw is diluted the major fraction of the switchable polarity solvent can be mechanically separated from the purified water after polar to nonpolar phase shift induced by introduction of 1 atm carbon dioxide to 1 atm of air or nitrogen with mild heating. Trace amounts of SPS can be removed from the separated water with RO in a process that avoids solution concentration polarization. The separated nonpolar phase can be regenerated to a full strength draw and recycled with the re-addition of 1 atm of carbon dioxide.
TL;DR: In this article, the removal of emerging contaminants from municipal wastewaters using a pilot system that integrated ultrafiltration (UF), reverse osmosis (RO), and electrooxidation, which mineralized the RO concentrate.
Abstract: This study aims to assess the removal of emerging contaminants from municipal wastewaters using a pilot system that integrated ultrafiltration (UF), reverse osmosis (RO), and electrooxidation, which mineralized the RO concentrate. Initially, the study monitored 77 emerging contaminants in the influent and effluent of a wastewater treatment plant (WWTP). Most of the compounds were detected in significant amounts in the WWTP effluent. A group of 12 compounds that represent the most prevalent therapeutic pharmaceutical categories was selected to monitor their removal by UF/RO. For the majority of the micropollutants, the UF removal efficiency was less than 20%. Excellent removal efficiencies were achieved with the RO treatment. As a result, the concentrations of the emerging contaminants in the RO permeate varied between 44 ng/L for naproxen and 4 ng/L for ofloxacin, and furosemide, bezafibrate and fenofibric acid were not detected. After the RO treatment, electrooxidation of the RO concentrate with boron-doped diamond electrodes reduced the total micropollutant content in the RO concentrate from 149 μg/L to less than 10 μg/L. Increasing the intensity of the electrooxidation treatment is expected to further reduce the micropollutant concentrations.
TL;DR: In this article, the influence of membrane pore size is investigated for the produced water, and the effect of feed flow rate, coolant temperature and feed temperature on permeate flux is studied.
Abstract: Air Gap Membrane Distillation (AGMD) has been implemented to treat produced water. The permeate fluxes, rejection factor and energy consumption for three different membranes, TF200, TF450 and TF1000, with pore sizes of 0.2, 0.45 and 1 μm, respectively, are measured at different operating parameters. The influence of membrane pore size is investigated for the produced water. Also, the effect of feed flow rate, coolant temperature and feed temperature on permeate flux is studied. The flux increases as the feed temperature and flow rate increase, and declines as the coolant temperatures increase. Moreover, the energy consumption was measured at different pore size and was found to be independent of membrane pore size.
TL;DR: In this article, polysulfone (PSf) substrates with different properties were made by varying the polymer concentration in the dope solution in the range 12-20% polyamide (PA) thin layers were then formed via interfacial polymerization between piperazine and trimethylchloride over the PSf substrates.
Abstract: In this work, polysulfone (PSf) substrates with different properties were made by varying the polymer concentration in the dope solution in the range 12–20 wt% Polyamide (PA) thin layers were then formed via interfacial polymerization between piperazine and trimethylchloride over the PSf substrates Both top PA thin layers and bottom PSf substrates were characterized with respect to physicochemical properties, structural morphology, and water flux/salt rejection to investigate the influence of substrate properties on the characteristics of PA thin layers Physical properties of the PA layers were reported to be altered using different PSf substrate properties and were in good agreement with the change in water flux From the FESEM pictures, it is found that the thickness of PA layer increased as the surface pore size of support membrane decreased The change in the membrane structural properties in particular pore size is found to portray significant contribution to the changes of formed PA layer Interestingly, only slight changes on Na 2 SO 4 and MgSO 4 salt rejection were reported on any TFC membranes Considering both water permeability and salt rejection rate, the best performing TFC membrane produced in this work was the membrane made over substrate of 15 wt% PSf concentration
TL;DR: In this article, a modification of the stepped solar still through internal reflectors was presented, and the effect of installing a reflecting mirror on the vertical sides of the steps of the step was investigated.
Abstract: This paper presents a modification of stepped solar still through internal reflectors. A comparison study between modified stepped solar still with trays (5 mm depth × 120 mm width) and conventional solar still was carried out to evaluate the developed desalination system performance under the same climate conditions. The effect of installing a reflecting mirror on the vertical sides of the steps of stepped still on the distillate productivity was investigated. An experimental as well as theoretical investigation is carried out. The results indicate that, during experimentation the productivity of the modified stepped solar still with and without internal reflectors is higher than that for conventional still approximately by 75% and 57%, respectively. Also the daily efficiency for modified stepped still with and without internal reflectors and conventional solar still is approximately 56%, 53% and 34%, respectively.
TL;DR: In this paper, the effectiveness of the bioprocess in delaying membrane wetting and the significance of the biofouling on flux decline was investigated. But, the results were limited to 13 days and the MDBR flux was not maintained at more than 6.8 L/m 2 h.
Abstract: The membrane distillation (MD) process is seldom employed in wastewater reclamation since the high organic and nutrient in wastewater promote wetting. The MD bioreactor (MDBR) can remediate this by biologically removing retentate carbohydrates and proteins. However, the inclusion of biomass in the MDBR can result in biofouling and flux decline. The objectives of this work are to determine the effectiveness of the bioprocess in delaying membrane wetting (by removing organics and nutrients) and the significance of the biofouling on flux decline. From this work, the MDBR flux can be maintained at more than 6.8 L/m 2 h (8% lower than the average MD flux) for at least 13 days. The faster flux decline in the MDBR is attributed to the thermal and mass transfer resistance of the biofilm but this can be controlled with periodic membrane cleaning and process optimization. Membrane fouling has been shown to compromise membrane hydrophobicity and accelerate wetting. By lowering the retentate organic and nutrient concentration, the MDBR has successfully delayed wetting by 1.7–3.6 times in this work, reducing the frequency of membrane cleaning and drying. With further process optimization, the MDBR could be a good option for reclamation of industrial wastewater with low volatile organic content and access to waste heat.
TL;DR: In this article, a phase change material (PCM) was added to the concentrator-coupled hemispherical basin solar still to augment the efficiency and distillate yield.
Abstract: In order to augment the efficiency and distillate yield in the concentrator-coupled hemispherical basin solar still, a phase change material (PCM) was added. Two modes of operation have been studied experimentally, (1) single-slope solar still without the PCM effect, and (2) single-slope solar still with the PCM effect. The temperature of water (Tw), temperature of PCM (TPCM), air temperature (Tair), inner cover temperature (Tic) and outer cover temperature (Toc) were measured. Experimental results indicate that the effect of thermal storage in the concentrator-coupled hemispherical basin solar still increases the productivity by 26%. It was concluded that the productivity greatly increased due to the still integrated with PCM.