Role Of Desalination Research Articles

Enhancing nanofiltration performance with tannic acid and polyvinyl alcohol interlayers for improved water permeability and selective solute rejection

Global water shortages have significantly intensified the demand for efficient and sustainable water purification technologies. Nanofiltration (NF) plays a crucial role in desalination, providing distinct advantages by removing a variety of pollutants including heavy metals and organic compounds, all while consuming minimal energy. Traditional NF membranes often struggle to balance high rejection with satisfactory permeability. This study advances NF technology by utilizing polysulfone as a durable substrate and introducing tannic acid (TA)-polyvinyl alcohol (PVA) interlayer to enhance structural robustness and functional capabilities of membranes. Through streamlined one-step coating followed by precise interfacial polymerization, this approach optimizes monomer piperazine storage and dispersion on substrate, effectively controlling its diffusion rate, resulting in a thinner polyamide (PA) layer. These strategic enhancements not only lead to a significant increase in permeability to 216.3 L·m−2·h−1·MPa−1 and an impressive rejection for Na2SO4 of 99.04 % but also ensure enhanced long-term operational stability. The innovative TA-PVA interlayer sets new benchmarks for high-performance NF membranes by combining environmental friendliness with cost-effectiveness, making it ideal for large-scale industrial applications. This unique composition promotes sustainability and economic efficiency in water treatment technologies, and underscoring the vast potential for expanding the production and application of advanced NF systems.

A novel dual-function antiscalant carboxymethyl cellulose-graft-protocatechuic acid for efficient scaling and biofouling prevention

Despite antiscalants playing a critical role in desalination and cooling water systems, their potential to support microbial growth pose a significant threat to water treatment processes by promoting biofouling. In this work, a novel dual-function antiscalant carboxymethyl cellulose-graft-protocatechuic acid (CMC-g-PA) was prepared using plant-derived antibacterial protocatechuic acid (PA) and natural polysaccharide cellulose, and its scale inhibition effect on CaSO4 scale and antibacterial performance on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated. Results indicated that the inhibition efficiency against CaSO4 scale and the induction time of CaSO4 crystallization process in the presence of CMC-g-PA were remarkably enhanced compared to unmodified CMC. Microscope and XRD characterizations demonstrated significant alterations in the crystal morphology and size of the formed scale using CMC-g-PA as antiscalant. Molecular dynamics (MD) analysis also showed that CMC-g-PA could intensively interact with the crystal plane of CaSO4 with the binding energy reaching 746.73 kcal/mol, thereby affecting crystal growth and causing crystal distortion. Additionally, an obvious inhibitory effect of CMC-g-PA on the growth of E. coli and S. aureus was observed, attributed primarily to the antibacterial activity of the introduced phenolic hydroxyl groups. In short, bio-derived CMC-g-PA, characterized in its environmental-friendliness, antiscaling efficiency and antibacterial activity, holds immense potential for mitigating scaling and biofouling in desalination/cooling water systems.

Influence of Concentration Gradients on Electroconvection at a Cation-Exchange Membrane Surface.

Membrane-based systems, such as electrodialysis, play an important role in desalination and industrial separation processes. Electrodialysis uses alternating anion- and cation-exchange membranes with a perpendicular electric field to generate concentrated and diluate streams from a feed solution. It is known that under overlimiting current conditions, reduced charge and mass transfer at the membrane interface leads to regions of high ion depletion generating instability and vortices termed electroconvection. While electroconvective mixing is known to directly impact the separation efficiency of electrodialysis, the influence of ion concentration gradients across the membrane experienced in a functional electrodialysis system is not known. Here, we report the influence of ion concentration gradients across a cation exchange membrane (Nafion) that is both aligned with and opposed to the applied electric field. Experiments were conducted by coflowing NaCl solutions of different concentrations (0.1-100 mM) on each side of the membrane, and electroconvection was visualized with a fluorescence dye (Rhodamine 6G). We obtained concentration profiles from fluorescence image data and systematically measured the thickness of the depletion boundary layer dBL under different conditions. We found smaller dBL values at a higher flow rate both with and without concentration gradients. Our results show that electroconvection is enhanced when the electric field is opposite to the direction of the concentration gradient.

Enhanced desalination with polyamide thin-film membranes using ensemble ML chemometric methods and SHAP analysis.

Addressing global freshwater scarcity requires innovative technological solutions, among which desalination through thin-film composite polyamide membranes stands out. The performance of these membranes plays a vital role in desalination, necessitating advanced predictive modeling for optimization. This study harnesses machine learning (ML) algorithms, including support vector machine (SVM), neural networks (NN), linear regression (LR), and multivariate linear regression (MLR), alongside their ensemble techniques to predict and enhance average water flux (AWF) and average salt rejection (ASR) essential metrics of desalination efficiency. To ensure model interpretability and feature importance analysis, SHapley Additive exPlanations (SHAP) were employed, providing both global and local insights into feature contributions. Initially, the individual models were validated, with NN demonstrating superior performance for both AWF and ASR, achieving the lowest mean absolute error (MAE = 0.001) and root mean squared error (RMSE = 0.0111) for AWF and an MAE = 0.0107 and RMSE = 0.0982 for ASR. The accuracy of predictions improved significantly with ensemble models, as evidenced by the near-perfect Nash-Sutcliffe efficiency (NSE) values. Specifically, the NN ensemble (NN-E) and Linear Regression ensemble (LR-E) reached an MAE and RMSE of 0.001 and 0.0111, respectively, for AWF. For ASR, NN-E reduced the MAE to 0.0013 and the RMSE to 0.0089, while LR-E maintained competitive performance with an MAE of 0.0133 and an RMSE of 0.0936. SHAP analysis revealed that features such as MDP and TMC were critical drivers of performance, with MDP showing the most significant positive impact on ASR. These findings demonstrate the dominance of ensemble methods over individual algorithms in predicting key desalination parameters. The enhanced precision in estimating AWF and ASR offered by these neuro-intelligent ensembles, combined with the interpretability provided by SHAP analysis, can lead to significant environmental and operational improvements in membrane performance, optimizing resource usage and minimizing ecological impacts. This study paves the way for integrating intelligent ML ensembles and SHAP-based interpretability into the practical field of membrane technology, marking a step forward toward sustainable and efficient desalination processes.

Insight into Ionicity Role in Desalination and Separation of Graphene Oxide Membrane

Insight into Ionicity Role in Desalination and Separation of Graphene Oxide Membrane

A Comprehensive Study on Ionicity Role in Desalination and Separation of Graphene Oxide Membrane

A Comprehensive Study on Ionicity Role in Desalination and Separation of Graphene Oxide Membrane

A Review on Recent Progress in Membrane Distillation Crystallization

AbstractMembrane distillation crystallization (MDC) is a promising hybrid separation technology that can play an important role in desalination, mineral recovery from liquid solution as well as in carbon dioxide fixation. MDC combines membrane distillation and crystallizer into one integrated unit that allows excellent recovery of clean water and high purity salt from highly concentrated salts solution (i.e., brine), which is otherwise detrimental when discharged to the environment. The process intensification addresses the limitation of standalone membrane distillation and a standalone crystallizer (i.e., temperature and concentration polarization, membrane properties) when operated as individual technology. This review discusses the fundamental of MDC focused on how the process intensification addresses those standalone units' limitations. Later, MDC's potential applications in addressing some pressing issues such as water scarcity and climate change are also evaluated. Lastly, current trends in the MDC research are discussed to project the required future developments.

Application of Titanium Dioxide Nanoparticles Synthesized by Sol-Gel Methods in Wastewater Treatment

Nanotechnology from titanium dioxide has been deposited, and its application in desalination and water treatment has been investigated by using sol-gel methods. Homogeneously dispersed sphere shapes of titanium dioxide nanoparticles were observed from scanning electron microscope micrographs and decrease in size as aging time increases from 40 min to 60 min. SEM micrographs of highly transparent nanopowders show that they are detected in the visible region from UV/visible and that their red shift around maximum wavelength increases with increasing aging time due to an increase in water quality. The energy band gap of the generated nanosheet has narrowed as the aging time has increased, which is related to the red shift of the absorption spectrum edge in the sheet. The structural behaviors of deposited nanoparticles have also been investigated, which confirms the existence of anatase as well as rutile levels in the liquid phase. The findings of the PL allowed us to determine the total strength of the intensity. This shows that applying photodegradation by a solar absorber could play a vital role in desalination and water treatment.

Substrate matters: The influences of substrate layers on the performances of thin-film composite reverse osmosis membranes

Abstract Thin-film composite (TFC) reverse osmosis (RO) membranes are playing the dominating role in desalination. Tremendous efforts have been put in the studies on the polyamide selective layers. However, the effect of the substrate layers is far less concerned. In this review, we summarize the works that consider the impacts of the substrates, including pore sizes, surface hydrophilicity, on the processes of interfacial polymerization and consequently on the morphologies of the active layers and on final RO performances of the composite membranes. All the works indicate that the pore sizes and surface hydrophilicity of the substrate evidently influence the RO performances of the composite membranes. Unfortunately, we find that the observations and understandings on the substrate effect are frequently varied from case to case because of the lack of substrates with uniform pores and surface chemistries. We suggest using track-etched membranes or anodized alumina membranes having relatively uniform pores and functionalizable pore walls as model substrates to elucidate the substrate effect. Moreover, we argue that homoporous membranes derived from block copolymers have the potential to be used as substrates for the large-scale production of high-performances TFC RO membranes.

The role of desalination in water management in southeast Spain

Ministerio de Economia y Competitividad (Spanish government), for the financial aid with Project CTM2013-46669-R.

The role of desalination in removal of the chemical, physical and biological parameters of drinking water (a case study of Birjand City, Iran)

One of the important components of public health is providing clean water in communities. According to documentations by international organizations, it is clear that high percentage of illnesses is directly related to water consumption in the society. Considering the fact that large mineral content in water can cause problems for consumers, the use of desalination to remove the minerals solute would therefore be a great idea in Iran. This cross-sectional descriptive study was performed to evaluate the role of six desalination devices (reverse osmosis) in Birjand that can remove chemical and physical parameter inputs such as nitrate, nitrite, total hardness, electrical conductivity (EC), chromium(VI), manganese, total dissolved solids (TDS), and microbial parameters (fecal coliform and total coliform) of water. One hundred and forty-four (144) samples of input and output point’s desalination were harvested and analyzed according to standard methods. The results showed that these devices could remove up to 90% chromium(VI), TDS, salinity, nitrite, from input water and 100% in many cases. The concentrations of chemical parameters in treated water were as follows: TDS = 262–369 mg/l, total hardness = 92–200 mg/l as CaCO3, nitrate = 4.31–11 mg/l, nitrite = 0 mg/l, Cr = 0–0.002 mg/l, Ca = 6.4–12.8 mg/l, Mg = 17.3–40.3 mg/l, Mn = 0 mg/l, salinity = 63 mg/l, pH range = 7–7.6, fecal coliform = 0 (MPN/100), total coliform = 0 (MPN/100), EC = 403.4–507.7 μs/cm and membrane flux retention coefficient = 1. Analysis of input and output data using paired t-test showed significant differences in these parameters (p < 0.05). Thus to remove high levels of mineral from drinking water in Birjand and since heavy metal chromium(VI) in the resource water in that area is higher than the standard requirement, using these systems can achieve good results.

Desalination for securing water productivity in an intensively used coastal aquifer (Campo de Dalías, Spain)

The Campo de Dalias aquifer is a coastal aquifer located in the southeast Spain (Andalucia). Since the 1960s, the area has experienced a spectacular economic development based on the intensive use of groundwater for the irrigation of greenhouse crops, becoming one of the world’s largest areas under greenhouses. This development, however, coincided with a rising groundwater demand from cities and tourism. The resulting fall in groundwater levels and seawater intrusion jeopardizes water security for the local economy based on intensive groundwater use. To remediate this situation, it is expected that from 2014–2015, part of the supply will be obtained from desalinated seawater, so as to reduce withdrawals. The main aims of this study are: first, to detail the water footprint in Campo de Dalias, and its productivity, with a particular focus on agriculture; second, review the process of seawater intrusion; and, finally, analyse the role of desalination as a solution to ensure water security for the multiple water uses and implications for cost recovery in the context of the European Union Water Framework Directive (WFD).

Characterization of forward osmosis membranes by electrochemical impedance spectroscopy

Forward osmosis (FO) has a potential role in desalination and water reclamation. However, the efficiency of FO processes is significantly limited by internal concentration polarization (ICP), which is difficult to detect by conventional characterization methods. In this work, we aimed to apply electrochemical impedance spectroscopy (EIS) to FO systems, and to develop a methodology for interpreting the interplay between the membrane structure and the polarization phenomena. Three commercial FO membranes with different substrate structures were characterized by an EIS system that was modified to accommodate FO processes, and the impedance spectra were analyzed based on their equivalent circuits. In the static tests (without osmosis), the limit behaviors of the impedance spectra were exploited to resolve the structural information of the FO membranes from the electrolyte background, which was in turn compared with the characterization results via scanning electron microscope (SEM). Associated with the different membrane orientations, the dynamic tests (with osmosis) were implemented to verify the ability of the EIS system to detect the variation of the developed concentration profiles within the membrane structure. The characterization results indicate that EIS is promising to be a handy tool to investigate the polarization phenomena during the FO processes.

Towards sustainable desalination

As the role of desalination in providing water is broadened, it has come under increasing scrutiny due to its perceived impact on the marine environment and its energy intensity. Desalination’s increasing popularity is due to lower cost technologies such as reverse osmosis along with the need to supply water to populations are moving towards the coast. Sustainable desalination is feasible when desalination projects are combined with demand management to ensure that the water is effectively used. There is appreciable scope to lower its energy demand through new technologies and approaches and by adopting desalination techniques wastewater can be recovered for potable and non potable use. Desalination can also play a positive role in relieving pressure on low flow rivers.

Options for water scarcity and drought management—the role of desalination

Recurring droughts across Europe have increased the awareness for the vulnerability of current water management systems at both national and EU level. While the European Commission contemplates concepts, member states are taking actions to cope with restricted availability of water resources. The paper presents a summary of drought planning activities of some water scarce regions. It can be shown, that all concepts include seawater desalination as key component of drinking water supply. Additionally, wastewater reuse plays another important role in mitigating water shortage. A more detailed analysis is given for Cyprus which shows that there is remarkable potential and the intention to combine the various elements of water savings, water reuse and exploring new water resources.

Flujos de agua, flujos de capital: sistemas de abastecimiento y gobernanza del agua en Madrid y Barcelona

El agua es un elemento clave para el sustento del metabolismo de las ciudades. Sin embargo, los orígenes, métodos de «producción», y modelos de gestión del flujo de urbano de agua pueden variar geográficamente. En este artículo se comparan los sistemas de abastecimiento y gestión de agua potable en las dos principales regiones metropolitanas del Estado: Barcelona y Madrid. En Barcelona, el agua procede de distintas fuentes entre las cuales destaca la desalación, vigente desde el verano de 2009. En Madrid, el sistema de abastecimiento depende fuertemente de las aguas superficiales procedentes de diversos ríos que atraviesan la Comunidad. Por lo que respeta a la gestión de estos sistemas el presente trabajo hace hincapié sobre las importantes diferencias que giran entorno al distinto balance entre participación pública y privada en el ciclo del agua en ambas áreas. Finalmente el artículo reflexiona sobre los puntos de convergencia y divergencia entre ambos modelos de abastecimiento así como sus perspectivas de futuro.

The role of desalination in augmentation of water supply in GCC countries

The growth gap between supply and demand for water in the GCC countries can be attributed to limited available surface water, high population growth and urbanization development, deficient institutional arrangements, poor management practices, water depletion and deterioration of quality, especially in shallow groundwater aquifers. Increasing demand for water in the domestic sector has shifted attention to the role of desalination in alleviating water shortages. Experience in the Gulf states demonstrates that desalination technology has developed to a level where it can serve as a reliable source of water at a price comparable to water from conventional sources. Desalination remains in GCC countries the most feasible alternative to augment or meet future water supply requirements. It is considered a strategic option for satisfying current and future domestic water supply requirements, in comparison to the development of other water resources. Reduction in cost is making desalination increasingly attractive in comparison with other alternatives. In this paper, the present and future water statues in GCC countries is outlined. The role of desalination for augmentation of water supply and the future needs for desalinated water are discussed. The cost analysis and the approaches for reducing the cost of desalted water are outlined. Increasing the investment in the research and development to reduce the costs through improved design and operation features is very important. Development of a water policy and effective strategies in each country for stressing the sustainable water resources management and optimizing allocation of water in accordance with market value, conservation, pollution control and cooperation among water involved institutions is also essential.

Implications of desalination for water resources in China — an economic perspective

China is a country with severe water shortages. Water is becoming scarcer due to population growth, industrialization and urbanization. Recent studies show that by the next 50 years water resources per capita will go down to around 1700 m 3, which is the threshold of severe water scarcity. Especially in North China, water shortage has become a critical constraint factor for socioeconomic development in the long run. To solve or eliminate water shortage problems, seawater desalination draws more and more attention as an alternative water supply source. The objective of the study is to assess the potential of desalination as a viable alternate water source for China through analysis of the costs of desalination, the water demand and supply situation as well as water pricing practices in China. Based on the investment costs and estimated operation and maintenance costs, an economic appraisal for the costs of desalination for two main processes, MSF and RO, has been conducted. The study shows that there is a decline of unit cost of desalination over time and the average unit cost of the RO process was lower than that of the MSF process. A unit cost of 0.6 $/m 3 for desalting brackish water and 1.0 $/m 3 for seawater are suggested to be appropriate for the potential application of desalination in China. Future trends and challenges associated with water shortages and water prices are discussed, leading to conclusions and recommendations regarding the role of desalination as a feasible source of water for the future.

Desalination: a viable supplemental source of water for the arid states of North Africa

The population of the states of North Africa (NA) will increase from 150 million in 2000 to about 250 million in 2025 with a corresponding increase in water demand for municipal, industrial and agricultural purposes. With this demand rapidly exceeding the water resources capacities, these states will soon face water shortages with serious adverse impacts on the sustainability of the region's environment and development. Desalination provides an alternate source of water which is reliable and readily available to the region's states. Desalination technologies have been in use in the region since the early seventies with a total installed capacity of over one million cubic meters per day presently. Cost factors have limited the uses of desalination to municipal and industrial applications. However, recent advances in desalination technologies have made desalination more competitive with new hard-to-find conventional water resources. The objective of this paper is to assess the potential of desalination as a viable alternate water source for the NA states through analysis of the water supply and demand situation in the region and the experience gained in desalination process applications. The future trends and challenges associated with water shortages and the desalination technologies potential in the region are discussed leading to conclusions and recommendations regarding the role of desalination as a viable supplemental source of water that will be progressively more feasible and cost effective particularly for satisfying the needs of the urban coastal communities in the region.

The role of desalination in bridging the water gap in Jordan

Over-abstraction of groundwater is one concern of the Badia Research and Development Programme. The upper aquifer of the Azraq basin forms the largest resource of good-quality water, but current abstraction exceeds both average recharge and the safe yield of the aquifer, which is over-exploited. Although there has been no deterioration in water quality and only minor drawdown, the springs at Azraq have dried up, with severe, undesirable environmental impacts. Total abstraction of 20 × 106 m3 yr−1 appears to be sustainable and would allow some springflow, but this leaves a shortfall of 40 × 106 m3 yr−1 for domestic supply and agriculture.