Article

The state of desalination and brine production: A global outlook

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Abstract

Rising water demands and diminishing water supplies are exacerbating water scarcity in most world regions. Conventional approaches relying on rainfall and river runoff in water scarce areas are no longer sufficient to meet human demands. Unconventional water resources, such as desalinated water, are expected to play a key role in narrowing the water demand-supply gap. Our synthesis of desalination data suggests that there are 15,906 operational desalination plants producing around 95 million m³/day of desalinated water for human use, of which 48% is produced in the Middle East and North Africa region. A major challenge associated with desalination technologies is the production of a typically hypersaline concentrate (termed ‘brine’) discharge that requires disposal, which is both costly and associated with negative environmental impacts. Our estimates reveal brine production to be around 142 million m³/day, approximately 50% greater than previous quantifications. Brine production in Saudi Arabia, UAE, Kuwait and Qatar accounts for 55% of the total global share. Improved brine management strategies are required to limit the negative environmental impacts and reduce the economic cost of disposal, thereby stimulating further developments in desalination facilities to safeguard water supplies for current and future generations.

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... Desalination plants worldwide are mainly located near the coastline due to the scarcity of freshwater resources, especially in the Middle East and North Africa region ( Figure 1). These existing facilities were designed to produce desalinated water for the municipal and industrial sectors [1]. During the last decade, the total desalination capacity has increased from 4.6 million m 3 /d to 99.8 million m 3 /d [2]. ...
... In other words, a large amount of waste brine was produced during desalination. The statistics in 2018 showed that the global production of brine reached 51.7 billion m 3 /year [1]. However, in most cases, the brine was directly discharged into the oceans [4,5], which created an inhospitable environment for cells of those marine organisms due to excessive osmotic pressure induced by high salinity [6]. ...
... As a result, the industry is seeking solutions to recycle brine for the sake of sustainable social development and ecological protection. [1]. Reprinted with permission from Ref. [1]. ...
Article
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The anti-corrosion property of fiber reinforced polymer (FRP) makes the concrete produced with marine wastes (waste brine after desalination) and resources (seawater and sea sand) a promising green structural material which can be a sustainable solution to fresh water and river sand scarcity in marine and offshore construction. To evaluate the feasibility of using waste and marine resources in concrete, this study investigated the mechanical properties and durability of brine-sea sand concrete (BSC) and seawater-sea sand concrete (SSC) with three different water-to-cement ratios and compared them to the corresponding ordinary concrete (OC). The results demonstrated that the increased salinity had a minor effect on the 28-day compressive strength, but a significant effect on the large-size capillary pore structure. The semi-quantitative analysis of the concrete phase based on the X-ray diffraction (XRD) and thermogravimetric analysis (TGA) revealed that BSC and SSC had larger mass fractions of the amorphous phase (mainly C-S-H), ettringite and gypsum during hydration. At last, the comprehensive performance of three different concrete mixtures was evaluated by five indexes (workability, alkali environment, compressive strength, carbonization resistance, and sulfate resistance). The results show that it is feasible to use brine/seawater and sea sand to replace freshwater and river sand for marine structural concrete reinforced with FRP.
... The desalination process uses seawater as the intake and removes the salts and minerals content in the process and ultimately produces freshwater that is suitable for human consumption and agriculture use, desalination remains a critical source of freshwater production in many water scarcity countries. The current desalination process comes with multiple methods such as multi-stage flash (MSF) distillation, multiple-effect distillation (MED), vapour compression, and reverse osmosis (RO) [4][5][6]. The current commercially viable desalination processes were dominated by MSF, MED and RO processes. ...
... Next, the MED process uses seawater as an intake and produces freshwater through multiple evaporators by reducing the pressure of the process [4]. Then, with the discovery of membrane technologies in the 1960s, the RO process started to gain popularity and slowly replace MSF and MED processes due to its space-efficient, scalable, and lower energy consumption [4][5][6]. RO process currently contributed 69% of the total volume of desalinated water produced, followed by MSF and MED both contributed 25%, and others by 4% [5]. To address the current desalination plant challenges high energy requirements, a sustainable solution with energy-efficient low-cost desalination and achieving zero carbon emission are critical for the future trend of desalination technology development. ...
... Then, with the discovery of membrane technologies in the 1960s, the RO process started to gain popularity and slowly replace MSF and MED processes due to its space-efficient, scalable, and lower energy consumption [4][5][6]. RO process currently contributed 69% of the total volume of desalinated water produced, followed by MSF and MED both contributed 25%, and others by 4% [5]. To address the current desalination plant challenges high energy requirements, a sustainable solution with energy-efficient low-cost desalination and achieving zero carbon emission are critical for the future trend of desalination technology development. ...
Article
Full-text available
Current desalination technologies such as thermal desalination and reverse osmosis are a process of converting seawater to freshwater. This method brings a negative impact on the environment such as CO 2 emission. Solar desalination is one of the ways to resolve the current desalination challenges and more sustainable in terms of economic and environmental. Solar desalination uses solar energy as its energy consumption for evaporation. Solar desalination depends on the rate of evaporation specifically on the surface area. Hence, this study adopts the concept of cellular fluidics and 3D printing to perform capillaries rise and improve the liquid to the gas-surface area. The increase in strut diameter of the cell from 0.2 mm to 0.4 mm results in an increase of capillaries rise from 3.01 to 7.67 for Body Centered Cubic (BCC) cell geometrical shape. Different cell geometrical shape is also investigated with the strut diameter remaining constant. The Isotruss cell geometrical shape recorded a value of capillaries rise of 11.76 among the other geometrical shape due to Isotruss having more complexity in design and having internal structure.
... The conversion of seawater or saline groundwater into drinking water increasingly provides a source of potable water in almost all Mediterranean countries, particularly in the eastern basin, the Arabian Peninsula and North Africa. Of the currently almost 16,000 operational desalination plants that are found in 177 countries, about half are located in the Middle East and North Africa region (Jones et al. 2019). In the Mediterranean Basin, desalination capacity has increased over the last few decades and the production of desalinated seawater in the MENA region is projected to be thirteen times higher in 2040 than 2014, the most advanced countries being presently Algeria, Egypt, Israel, Italy and Spain (UNEP/MAP and Plan Bleu 2020). ...
... The impingement and entrainment of marine organisms associated with the seawater intake of a desalination plant represents a further disadvantage (Elimelech and Phillip 2011). The discharge of high-salinity brines as well as of the chemicals used in the pretreatment and membrane-cleaning protocols into the sea adjacent to a desalination plant adversely affects near coastal marine ecosystems and represents an environmental problem that is increasingly recognized (Lattemann and Höpner 2008;Elimelech and Phillip 2011;Missimer and Maliva 2018;Jones et al. 2019). ...
... While promising new (solar) technologies are being developed, they still have their drawbacks and need to prove their economic feasibility. Importantly, operators will have to deal with the environmental repercussions of desalination and significant adverse impacts on near-coastal marine ecosystems (Missimer and Maliva 2018;Jones et al. 2019). ...
... Although catalyst engineering using polyanion coatings to suppress corrosion by chloride ions or creating highly selective electrocatalysts has been extensively exploited with modest success, it is still far from satisfactory for practical applications [8][9][10][11][12][13][14] . Indirect seawater splitting by using a pre-desalination process can avoid side-reaction and corrosion problems [15][16][17][18][19][20][21] , but it requires additional energy input, making it economically less attractive. In addition, the independent bulky desalination system makes seawater electrolysis systems less flexible in terms of size. ...
Article
Full-text available
Electrochemical saline water electrolysis using renewable energy as input is a highly desirable and sustainable method for the mass production of green hydrogen1–7; however, its practical viability is seriously challenged by insufficient durability because of the electrode side reactions and corrosion issues arising from the complex components of seawater. Although catalyst engineering using polyanion coatings to suppress corrosion by chloride ions or creating highly selective electrocatalysts has been extensively exploited with modest success, it is still far from satisfactory for practical applications8–14. Indirect seawater splitting by using a pre-desalination process can avoid side-reaction and corrosion problems15–21, but it requires additional energy input, making it economically less attractive. In addition, the independent bulky desalination system makes seawater electrolysis systems less flexible in terms of size. Here we propose a direct seawater electrolysis method for hydrogen production that radically addresses the side-reaction and corrosion problems. A demonstration system was stably operated at a current density of 250 milliamperes per square centimetre for over 3,200 hours under practical application conditions without failure. This strategy realizes efficient, size-flexible and scalable direct seawater electrolysis in a way similar to freshwater splitting without a notable increase in operation cost, and has high potential for practical application. Importantly, this configuration and mechanism promises further applications in simultaneous water-based effluent treatment and resource recovery and hydrogen generation in one step.
... Another challenge is brine production, which makes management and disposal both costly and environmentally hazardous. New strategies for safe disposal will reduce costs and save the environment (Jones et al. 2019). During the last decades, solar energy cost has been decreasing. ...
Article
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Due to disparities in the allocation of rainwater and drought, extreme exploitation of groundwater reservoirs has depleted water supplies in many locations. In addition, improper disposal of domestic and industrial waste leads to poor drainage and deterioration of water quality. According to studies, desalination methods are an effective solution for treating unconventional water, i.e., sea and brackish water, and making it usable in daily life. Solar-powered desalination has recently received a great deal of attention around the world. Herein, we summarized challenges and future perspectives associated with solar-powered desalination units. Some hybrid technologies are also discussed like solar-wind desalination and RO-ED crystallizer technology in Morocco and the Middle East and North Africa (MENA) region. Previously, most experimental studies focused on the use of solar energy in traditional desalination methods such as multistage flash and multi-effect distillation. Desalination with reverse osmosis has become popular due to membrane technology improvement and benefits like high recovery ratios and low energy consumption. Furthermore, it has been seen that solar energy is less expensive than the energy obtained from traditional fuels in the MENA area. This article aims to comparatively and systematically review the economic feasibility of the use of solar photovoltaic reverse osmosis in desalination in the MENA region.
... Over the years, membranes-based technologies such as reverse osmosis (RO) and nanofiltration (NF) took over conventional desalination processes owing to their smaller footprint, and energy-effective features (Khawaji et al., 2008). RO accounts for nearly 70% of the produced desalinated water (Jones et al., 2019). Yet, high operating pressure (>30 bar) urges efforts to seek nanofiltration (NF) as an alternative/pretreatment . ...
Article
Electrically-conductive membranes became the center of attention owing to their enhanced ion selectivity and self-cleaning properties. Carbon nanostructures (CNS) attain high electrical conductivity, and fast water transport. Herein, we adopt a water-based, simple method to entrap CNS within Alginate network to fabricate self-cleaning nanofiltration membranes. CNS are embedded into membranes to improve the swelling/shrinkage resistivity, and to achieve electrical-conductivity. The CaAlg PEG-formed pores are tuned by organic-inorganic network via silane crosslinking. Flux/rejection profiles of Na2SO4 are studied/optimized in reference to fabrication parameters. 90%-Na2SO4 rejection (7 LMH) is achieved for silane-CaAlg200-10% CNS membranes. Membranes exhibit outstanding electrical conductivity (∼2858 S m⁻¹), which is attractive for fouling control. CaAlg/CNS membranes are tested to treat dye/saline water via two-stage filtration, namely, dye/salt separation and desalination. A successful dye/salt separation is achieved at the first stage with a rejection of 100%-RB and only 3.1%-Na2SO4, and 54%-Na2SO4 rejection in the second stage.
... Due to rapid industrialization, urbanization and other anthropogenic activities, water resources managers worldwide are pushing toward water desalination as a viable solution for water scarcity (Ahmed and Anwar, 2012). Recent estimates suggest that more than 100 million cubic meters of desalinated water are produced daily from approximately 16000 desalination plants in 177 countries worldwide (Jones et al., 2019). Those desalination plants alter the water characteristics of the nearby water system. ...
Article
Dissolved oxygen (DO) is one of the most significant environmental indicators of water quality. Preservation of reasonable DO concentrations is essential for a healthy aquatic life. In this research, numerical simulations of DO concentrations were discussed using TELEMAC-WAQTEL-O2 model. Firstly, the model was verified by comparing its results to analytical solutions in different 1D and 2D cases considering pulse and constant DO injections. Based on the very good agreement between the model and analytical results in different simulation scenarios, the TELEMAC-WAQTEL-O2 model has proven its ability to be applied to more complex cases. Consequently, this model was applied to investigate El Gouna artificial lagoons in Egypt under the effect of different weather conditions including tide, mean and maximum wind and different water temperatures. Investigating the water quality of El Gouna lagoons is important to monitor negative anthropogenic impacts to protect the lagoons and the nearby Red Sea coast. Negative effects of effluents from a nearby desalination plant on DO concentration were discussed considering different brine discharges, DO concentrations of brine discharge, injection times and weather conditions. This study presents one of the few systematic DO studies on artificial lagoons considering hydrodynamics and water quality issues. The results show a decrease in DO concentrations affected by high water temperatures. Further, the lagoons’ hydrodynamic has a relevant impact on DO concentrations, e.g., tide wave induced DO concentrations to increase and decrease following a sinusoidal wave. Also, winds affect the DO propagation as low DO concentrations are obtained near the inflow boundaries. The outcomes demonstrate that DO concentrations depend on the lagoons’ hydrodynamics, DO’s production and consumption rate and tracer transport. The polluted water with low DO concentrations flowing from the desalination plant followed the wind direction. Besides, different quantities of binary and different injection times have minor effects on DO concentrations in the lagoons.
... As a consequence of water scarcity that is currently affecting Chile, as well as many other countries in the world, the use of seawater as a water resource for industrial processes, e.g., mining, has progressively increased in the last decades [1]. Usually mining areas are far from the coastline, which implies the transportation of seawater for long distance (longer than 100 km) is performed by pipelines [2,3]. ...
Article
Full-text available
The use of seawater for mining purposes in Chile has progressively increased in recent years as fast as the interest on the negative effects of biofouling on the inner part of pipelines used to transport seawater. To prevent biofouling, chemical antifouling compounds are traditionally used, thus, causing negative environmental impacts. The aim of this research has, therefore, been to evaluate the efficiency of static magnetic fields (SMF) generators to mitigate the biofouling. Hence, experimental activities have been conducted on high density polyethylene (HDPE) pipes equipped with neodymium magnets during two experimental periods in the year of 2019, i.e., autumn–winter (A–W) and spring–summer (S–S), and under two types of SMF, i.e., continuous-type (PCS) and pulse type (PPS). Physicochemical parameters and cell viability of microorganisms composing the biofilm were investigated. Metagenomic analyses on biofilm were conducted as well. The results showed that the cell viability was the highest, i.e., 757,780 cells/cm2, during S–S and the lowest, i.e., 349,151 cells/cm2, in A–W, both under PCS. In S–S, as well as A–W, biofilm was characterized for the most abundant eukaryotic operational taxonomic units (OTUs) under PPS conditions. The presence of OTUs, such as Articiflavibacter spp., Chaetonotida spp. and Desmodorida spp., was observed only from SMF tests.
... Some of the membrane-based techniques are reverse osmosis (RO), forward osmosis (FO), and membrane distillation (MD) (Amy et al. 2017). The implementation of these versatile membranes in existing technologies depends on the improvement of the membranes regarding the material, fabrication methods, production and working expenses, environmental issues, et al. (Werber et al. 2016b;Jones et al. 2019). The last attribute includes energy consumption, materials selection, produced gases, and liquid wastes. ...
Article
Developing environmentally friendly and inexpensive membranes for water purifying applications is a global challenge. Graphene oxide is one of the most-studied and tailorable materials for membrane fabrication; however, adjustment of interlayer spacings for an efficient desalination performance has not yet been fully achieved. Herein, graphene oxide was reduced with ascorbic acid for 5–180 min. The partially reduced graphene oxide was utilized through vacuum filtration for membrane preparation. Reduced samples for 5–20 min could form intact membranes, which showed excellent water flux (58–178 L m−2 h−1 bar−1) and efficiently reduced NaCl permeability. Besides, the partially reduced graphene oxides revealed dual interlayer spacings related to almost graphitic domains and semi-reduced domains comprising oxygen-containing functional groups. By investigating the water flow and ion permeation mechanism, the remaining oxidized domains and the major types of functional groups were found to be modulating, respectively. This study showed that partial reduction could be facilely exploited to fabricate graphene oxide-based membranes with adjustable interlayer spacing capable of salt blocking.Graphical Abstract
... l'Espagne, Caraïbes au Sud-Est Asiatique, etc. L'Arabie Saoudite reste cependant le plus gros producteur d'eau potable issue de dessalement (Galland et al., 2008;Mericq, 2009;Elimelech and Phillip, 2011;Ben Fadhl, 2019;Jones et al., 2019). ...
Thesis
This work aims to study the impact of the installation of seawater desalination plant in Agadir bay by drawing up the initial health state of two marine ecosystems Tifnit-Douira and Cap Ghir receiving desalination plants. Thus, a multidisciplinary study was conducted in the sentinel species Mytilus galloprovincialis, combining two complementary approaches: i) the chemical approach (physico-chemistry and chemical detection of pollutants); and (ii) the biological approach (ecotoxicological study of multi-biomarker response and reproductive biology). An inventory of macro-phyto/zoo-benthic species associated with mussel beds was also carried out to assess the biodiversity of these ecosystems. Our results related to the physicochemical approach in the two studied stations reveal values that oscillate between: 16.24 and 21.61 °C for seawater temperature; 7.39 and 8.73 for pH; 43.15 and 65.16 mS/cm for conductivity and between 27.40 and 43.75 PSU for salinity. TDS and dissolved oxygen values vary between 21.14 to 31.88 and 4.33 to 8.14 mg/l respectively. These parameters follow monthly fluctuations in the two studied ecosystems due to the marine environmental responses to changes in daily and weekly climatic conditions and also to seasonal hydrodynamic factors (currents, swell and upwellings). The study of metal pollution in both ecosystems has shown that their concentrations undergo monthly, seasonal and annual fluctuations depending on the dosed element. Cd, Pb and Cu recorded relatively high levels (2.28, 2.50 and 6.86 mg/kg respectively) with comparable annual profiles between the two stations. While Arsenic (As) oscillates between 7.97 and 12.60 mg/kg without reaching the toxicity threshold of 14 mg/kg. The measured values are significantly high, especially at Cap Ghir with a stability of the values throughout the study period. This attests to the presence of Arsenic in a natural way in the Atlantic marine ecosystem. The results obtained for the major metal elements studied showed maximums of 6.33, 145.51 and 285.74 mg/kg respectively for Mn, Fe and Zn. The revealed annual patterns appear similar between the two ecosystems with moderate seasonal fluctuations. Biomarker response measures, Acetylcholinesterase (AChE), Glutathione-S-Transferase (GST), Catalase (CAT) and Malondialdehyde (MDA) in Mytilus galloprovincialis, have been shown to be present in measurable and inducible amounts. In addition, response levels fluctuate respectively between 1.94 to 8.85; 3.74 to 36.91; 3.52 to 17.94 and 1.13 to 5.91 nmol/mg protein. This is explained by the response of these molluscs, to variations in environmental conditions as well as to the presence of certain contaminants including heavy metals mainly Cadmium, and consequently to the physiological disturbances of the species during its development cycle. The study of reproductive cycle in the mussel Mytilus galloprovincialis, testifies to a continuous sexual activity throughout the year with periods of collective egg-laying coinciding with spring and summer. The number of these collective gametic release varies between two to three periods depending on the environmental conditions, especially variations in seawater temperature. This results in a lack of collective sexual rest period in these mussel populations. The sex ratio study shows a balance between males and females of 1.14:1 in Tifnit-Douira, and it varies between 1.12:1 to 1.18:1 in Cap Ghir. The histological study allowed the detection of a single case of hermaphroditism, revealed for the first time in mussel populations in the Agadir bay. The values of the condition index are high (>60) in Mytilus galloprovincialis of the studied stations during all seasons even during laying periods. The favorable conditions of the environment allow a continuous allometric and weight growth throughout the year. Regarding biological diversity, both stations have a very high diversity of Macro-Phyto/Zoo-benthic species. Indeed, the animal kingdom is rather dominated by Crustaceans and Gastropods, while Chromophytes and Rhodophytes are the most dominant in the plant kingdom. All these results prove the well-balanced state of the environment in the two studied ecosystems Tifnit-Douira and Cap Ghir; and that permanent monitoring should be realized to protect their health state from the impact of desalination plants. Keywords: Mytilus galloprovincialis, Agadir Bay, Cap Ghir, Tifnit-Douira, Desalination, Biomarkers, Marine ecosystem, Heavy metals, Reproductive cycle, Biodiversity, Biomonitoring.
... According to a United Nations-sponsored study, Jones et al. [360] published a report in 2019 titled 'The state of desalination and brine production: a global outlook,' in which they highlight the advantages of providing drinking water from desalination plants while also pointing out the numerous drawbacks. Economic and technological challenges in brine management are also highlighted in the report. ...
Article
Full-text available
The scarcity of drinkable water supplies is becoming a serious and troubling challenge to long-term development. This issue emphasises the urgency of implementing rapid water desalination options. However, desalination is a capital-intensive process that requires a significant amount of energy, and since it is now mostly powered by fossil fuels across the globe, it has the potential to leave a significant carbon footprint. In this light, transitioning to green energy sources for desalination is a necessity in today’s society. Humidification–dehumidification (HD) is one of the most effective desalination procedures to consider for distant places with modest fresh water demands for household and agricultural demands. This is mostly because it requires minimal operational and maintenance concerns. The current article examines the many kinds of HD desalination systems driven by solar energy sources and their key components. The current study established that the seawater HD system is viable for producing fresh water, especially for greenhouses and dispersed demand. HD is an effective technique for eluting fresh water from concentrated brines, boosting production, and minimising harmful environmental impact, benefitting ecosystems and human services. The packed bed humidifier is the most commonly used kind of humidifier in the HD water desalination system. Additionally, as compared to an indirect dehumidifier, the direct dehumidifier improves the performance of the HD desalination system. According to the findings of this research, hybrid energy systems have the greatest gain output ratio (GOR). Solar water heating significantly increases system productivity as compared to solar air heating. When combined with a heat pump, the HD delivers optimal system productivity and GOR at the lowest cost per litre. The conclusion is that, even though humidification–dehumidification is a promising method for decentralised small-scale fresh water production applications, it needs additional improvement to optimise system performance in terms of economy and gain output ratio.
... To safeguard future water supplies and marine life, the region may seek to manage brine in ways that limit the negative environmental impacts and reduce the economic cost of disposal. New and existing water and energy infrastructure projects can be evaluated for potential environmental impacts of discharge, with adverse effects mitigated as far as possible (Jones et al. 2019). Note: MED = multi-effect distillation; MSF = multistage flash; RO = reverse osmosis. ...
Technical Report
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Climate change and a growing population make it increasingly urgent to find ways to better manage the water-energy nexus. The desalination, pumping, distribution, and treatment of water require significant energy resources. The extraction of energy resources and production of energy, meanwhile, consume substantial amounts of water. In addition, negative environmental effects often follow poor management of the water and energy sectors. Up till now, reform policies have not adequately addressed the challenges. Water and energy subsidies deepen the dependence of both the water and energy sectors on oil revenues. A strong reliance on cheap energy for the provision of water security will, in the long run, be unsustainable. Reform efforts should aim for a proactive and coordinated approach that can lead to a green, inclusive, and more resilient low-carbon economy. The report highlights the challenges the Gulf region is facing in relation to the water-energy nexus, and at the same time highlights the opportunities going forward, drawing, in part, on key innovations in the region. Moving forward on this critical agenda will require action on several levels. The region can transition to greater reliance on renewable sources of energy for desalinizing seawater, scale the use of renewables to decrease emissions, introduce measures to replenish marine habitats, invest in research to drive innovation, move toward policies and tariffs that encourage more efficient use, and leverage wastewater as a valuable asset for improving water security.
... The United Arab Emirates (UAE) is well-positioned in this context, considering that 42% of its total water requirement is met through the desalination process (The United Arab Emirates ' Portal, 2021). According to a study by United Nations University Institute on Water, Environment, and Health (UNU-INWEH), the UAE alone is responsible for 20.2% of the global brine production, which is estimated to be 10.4 billion m 3 /y (Jones et al., 2019). Such reject brine from desalination is often released directly into the sea, threatening marine life and ecosystems due to its high salinity and elevated temperature (Lattemann and Höpner, 2008). ...
Article
A cradle-to-gate life cycle assessment (LCA) approach is carried out to determine the environmental impact of brucite (Mg(OH)2) and synthetic magnesium oxide (MgO) recovered from reject brine in the United Arab Emirates (UAE) using SimaPro 9.1 software. The environmental impacts of synthetic Mg(OH)2 and MgO production were quantified using 18 ReCiPe midpoint indicators. Four different alkali sources, calcium oxide (CaO), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), and ethanolamine (C2H7NO), which can be utilized for the production of synthetic MgO, are considered. The results demonstrate that CaO was the most environmentally friendly alkali that can be used to produce synthetic Mg(OH)2 with the lowest environmental impact in all 18 ReCiPe midpoint indicators. The results for brucite and synthetic MgO production in the UAE were scaled up from laboratory experiments for LCA analysis and compared to the results of commercial MgO produced from the calcination of magnesite (MgCO3). The carbon dioxide equivalent (CO2 eq.) emissions for synthetic MgO generated from reject brine using CaO are 6.7–25.2% higher than that from commercial MgO. However, synthetic brucite recovered from reject brine using CaO produces 28.8–37.1% less CO2 eq. emissions compared to commercial MgO, making it a promising magnesium-based binder that can be adopted in the UAE.
... The steady increase of desalination across the region was fostered by economic growth coupled with cheap energy (Parmigiani, 2015). Nowadays, with almost half of desalination capacity worldwide, the GCC countries are among the main global producers of desalinated water; their share in global desalination capacity ranges from 18% in Saudi Arabia, 10.1% in the United Arab Emirates and 3.7% in Kuwait ( Jones et al., 2019). In 2016, the average share of desalinated water in municipal water supply across the region was 83.5% and the annual desalination capacity amounted to 7725 hm 3 (Table 26.3). ...
Chapter
Water security has been an ongoing challenge in the Gulf Cooperation Council (GCC) region. Due to the hot climate, marked by low and infrequent rainfall and high evaporation, water is a highly scarce resource, and the six GCC states (viz., Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates) are considered in absolute water scarcity situations. Additionally, overexploitation of fossil groundwater resources has already affected the aquifers’ quality. With enormous hydrocarbons reserves, the GCC countries have turned to desalination to meet domestic water supply requirements. However, desalination remains a capital-intensive technology and costly process, with adverse environmental effects. Meanwhile, the reuse of treated wastewater is limited. Further, the multiple impacts of climate change, population growth, and rapid economic development will add stress to scarce water resources. Indeed, the extent to which GCC countries manage water security challenges will depend on the government's policies over the short, medium, and long term. Therefore, this chapter addresses the governance and political economy of water as well as water solutions and policies.
... which include seawater and brackish water, and human created saline waters, such as desalination concentrates, industrially produced waters, and salinized groundwater supplies due to agricultural runoff. Currently, seawater is the main source of feedwater for desalination processes [9][10][11]. Seawater feeds typically have total dissolved solids (TDS) concentrations ranging from 32,000 ppm to 40,000 ppm, depending on the region of the world. ...
Article
Pervaporation is a vapor pressure-driven membrane desalination process that can desalinate water with greater total dissolved solids than conventional reverse osmosis. This review analyzes the performance (flux and permeance) of membrane materials used for pervaporation desalination. Poly(vinyl alcohol) (PVA), silica/silicate, graphene oxide (GO), and zeolite were the most frequently used materials to synthesize pervaporation desalination membranes. PVA is the most common material and it yields a relatively high permeance. Surface free energies of different materials were evaluated as well, to analyze the scaling/fouling propensity of the current common pervaporation desalination membranes. PVA is found to be more likely to experience scaling by gypsum while adding organic silica/silicate or GO has the potential to mitigate this issue. When comparing PVA and polyvinylidene fluoride, the hydrophobic polymer is more likely to experience scaling/fouling than hydrophilic polymers. These results indicate that future development in membranes for high-efficiency pervaporation desalination may benefit from emphasizing materials with higher hydrophilicity.
... creases the demand for potable and irrigation water. Even though 70 percent of the Earth is covered with water, most of it is saline. Hence, there exists a large interest in desalination technologies to ensure water sustainability and production of potable water from brackish or seawater via reverse osmosis (RO) stands out as the leading technology(Jones et. al., 2019). Polyamide (PA) based thin film composite (TFC) membranes are extensively used in seawater reverse osmosis (SWRO) applications due to their superior separation performance and stability. Thin film nanocomposites (TFN) are promising to overcome the important limitations in SWRO applications, such as permeability-selectivity trade-off and ...
Conference Paper
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The past decade has seen the rapid development of Graphene Quantum Dots (GQDs) in many areas. GQDs are excellent materials due to their large diameter, high surface area, high mechanical strength, high elasticity, thermal stability, and good electrical conductivity like graphene [1–4]. GQDs which have nanoscale small sections of graphene are a zero (0) dimensional nanomaterial. Compared to graphene, GQDs have a non-zero bandgap due to the quantum confinement effect in all dimensions [5]. This bandgap can be adjusted by varying the size and surface chemistry of the GQDs [6]. An objective of this study was to investigate GQDs on p-type Si-based hybrid structure diode parameters. These steps were followed to fabricate the GQDs Schottky diode. Firstly, nitrogen-doped GQDs were successfully prepared via a one-step hydrothermal method using citric acid (CA) and polyethyleneimine (PEI) as the carbon, nitrogen, and amino group precursors, respectively. Second, GQDs solutions was spin-coated on the p-type Si wafer. Finally, Aluminum (Al) (99.999% purity) was deposited to obtain ohmic and rectifying contacts. Current-voltage (I-V) characteristics of the diode were analyzed at room temperature. Diode parameters such as barrier height (Φb) and ideality factor (n) of the structure were extracted by Thermionic Emission (TE). The values of Φb obtained from TE, were found to be 0.76 eV. Also, the values of n obtained from TE theory was found to be 3.71. The rectification ratio (RR) of the structure was found to be about 1000 at ± 5 V. The obtained results suggest that the NIR active GQDs hybrid structure can be used in various device applications such as solar cells and transistors.
Article
Pulsing the electric field is an operational strategy for suppressing concentration polarization (CP) in electrodialysis (ED). In this study, the effects of pulsing parameters on the desalination performance of ED were investigated. Experimental analyses were performed at sub-limiting and limiting regimes for frequencies of 0.5–100 Hz and duty cycles of 20–80 %. A 1-D transient model was developed to calculate the concentration profiles inside the cell. The results indicated that under the same input voltage, the cycle-averaged current density of the pulsed ED (PED) increased at higher frequencies and duty cycles while always remaining below the current density of conventional ED (CED). The energy savings gained from suppressing CP compensated for the inefficiencies introduced due to the longer desalination time, resulting in approximately similar specific energy consumption (SEC) compared to CED. Pulsed operation increased the limiting voltage, allowing for higher input voltages without intensifying water dissociation. However, increasing the pulsing voltage led to a higher SEC and reduced the effectiveness of the approach for suppressing CP. To enhance the viability of PED, pulsing parameters should be tuned according to the desalination objectives. This study provides the required insights for developing a generalizable optimization approach for PED.
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Desalination is a process of getting potable water by treatment of highly saline brackish or sea water. The techniques are being adopted to treat sea water (67%), brackish water (19%), river water (8%) and waste water (6%) which can further help to cope up with the condition of water crisis. Global desalination techniques (i.e. reverse osmosis (RO), multistage flash (MSF), multi-effect distillation (MED)) are currently utilizing around 75.2 TWh of energy per year. These techniques need a continuous supply of power for their proper functioning. In remote areas renewable energy resources are used as power supply for smooth working of plants. Among these energy resources nuclear energy is found to be highly efficient energy that can be used to treat sea water. The energy produced from nuclear reactors can be coupled with thermal desalination units and can further used to treat water. The pressurized water reactor (PWR) is highly cost efficient and reliable technology that is being coupled with desalination unit for the treatment of highly saline water. Results from DEEP analysis showed that reverse osmosis system (RO) coupled with nuclear reactor are proved to be highly cost efficient and can provide high quality freshwater. The average cost for such type of unit is found to be 0.787 $/m3. The study concluded that coupling desalination units with nuclear reactors can provide clean water at comparatively lower cost.KeywordsDesalinationPressurized water reactor (PWR)Nuclear reactorRenewable energy (RE)Cost analysis
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Desalination is highly suitable technique in current era of water crisis especially in arid and semiarid regions. The techniques are being adopted worldwide with a capacity to treat sea water (67%), brackish water (19%), river water (8%) and waste water (6%) which can further help to cope up with the condition of water crisis. Global desalination techniques (i.e. reverse osmosis (RO), multistage flash (MSF), multi-effect distillation (MED)) are currently utilizing around 75.2 TWh of energy per year. These techniques need a continuous supply of power for their proper functioning. In remote areas renewable energy resources are used as power supply for smooth working of plants. Among these energy resources nuclear energy is found to be highly efficient energy that can be used to treat sea water. The energy produced from nuclear reactors can be coupled with thermal desalination units and can further used to treat water. Results from DEEP analysis showed that PHWR-600 nuclear reactor coupled with reverse osmosis system (RO) is proved to be highly cost efficient and can provide high quality freshwater. The coupled process can provide fresh water at even more lowest cost as compared with nuclear reactors coupled with MED and MSF technologies.KeywordsDesalinationPressurized water reactor (PWR)Nuclear reactorRenewable energy (RE)Cost analysis
Article
The current work highlights development of novel thin-film composite hollow fiber membranes for pressure retarded osmosis applications to harvest salinity gradient energy. The membranes were developed with a specific target of harnessing the salinity gradient energy between wastewater reverse osmosis retentate and seawater reverse osmosis brine via osmotic mixing. The hollow fiber membranes were prepared by coating a polyethersulfone substrate with a thin-film composite polyamide layer via interfacial polymerization, which were assembled into modules of different diameters for lab scale and pilot scale evaluation. As the module size increased from 1-in. to 2-in., and 4-in., the water permeability, tested against a 1000 mg/L sodium chloride solution at 15 bar, decreased from 2.6 L m⁻² h⁻¹ bar⁻¹ to 2.0 L m⁻² h⁻¹ bar⁻¹, and 1.2 L m⁻² h⁻¹ bar⁻¹, respectively. The power density, measured in the lab-scale unit using 1 M sodium chloride draw solution, and DI water feed solution, also decreased from 9.1 W/m² to 5.3 W/m² with increasing module size. Pilot scale evaluation of the 4-and 8-in. modules on a 24 m³/day unit resulted in lower power densities of 2.5 W/m² and 1.5 W/m² which translated to 0.024 kWh/m³ and 0.05 kWh/m³ of salinity-gradient energy harvested, respectively.
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This chapter discusses innovative systems based on seawater reverse osmosis desalination driven by hybrid tidal-range/solar photovoltaic (PV) energies. A review of research activities focused on tidal-powered desalination and proposals of energy storages is presented. Moreover, a preliminary design analysis is carried out. Recommended designs considering single-mode tidal-range plants referred to the desalination plant capacity based on the case study carried out would be: 25.0 MW of tidal turbines and 31.1–34.3 MWp per 100.000 m³/d of nominal capacity, considering 3.5 kWh/m³ of specific energy consumption. In other words, 1.71 MW rated of tidal turbine and 2.15–2.35 MWp of PV field are required per MW of nominal consumption of the desalination plant. Further design analysis should be carried out before setting a realistic range of product costs. However, contribution of investment costs per m³ of water produced with recommended designs amounts to about 0.67 $/m³ considering the following investment costs of main subsystems from the literature.
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Desalination is a class of processes to produce freshwater from saline waters and is considered a concrete option to cope with the scarcity of natural water resources. Nevertheless, desalination is an energy-intensive process, and it is essential to ensure it uses renewable energy sources to make it sustainable for a long period. This chapter proposes an approach to the large-scale screening of desalination driven by renewable energy based on indicators of feasibility and costs, allowing the comparison of different energy storage options (electric grid, batteries, and water reservoirs) necessary to deal with the intermittency of renewable production. A case study over the extended Mediterranean region is presented, considering reverse osmosis completely driven by photovoltaic energy over a large number of potential desalination sites, but the procedure can be readily extended to other technological and geographical contexts.
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Water scarcity poses one of the greatest threats to conventional irrigation systems, a sector whose water demand is continuously growing. Despite the reliance on irrigation, the average global irrigation efficiency is estimated to be only 35%, with a maximum growth of 0.3% per year relative to the respective basis. As freshwater resources dwindle, seawater desalination becomes an increasingly reliable and cost-competitive water supply not just for municipal and industrial sectors, but also the irrigation sector. Improvements in the water use efficiency of the global irrigation sector can reduce the global water demand by 10%–30% by 2050, relative to a business-as-usual scenario. The corresponding reduction in demand for desalinated water is estimated to be about between 30% and 60%. In addition, transitioning the global seawater desalination sector from the current fossil-based system to a 100% renewable-energy-based sector by 2050 enables water production costs globally in the range of 0.32––1.66 €/m³. Solar photovoltaics and battery energy storage are the key pillars of the energy supply system for low-cost desalination. Improvements in irrigation efficiency can reduce the investments required for the energy system by as much as 60%.
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Desalination is an alternative source of water supply, which can reduce the increasing pressure on freshwater resources. Recently, to overcome the shortages, it is being used in areas where people are facing acute freshwater shortages, e.g., in coastal cities. This chapter will focus on how desalination and other water management solutions can be an effective alternative to reducing the impact of climate change on freshwater. It will be expected that by 2050, many regions in India will face severe water scarcity. In this chapter, the authors discussed how this natural resource/ecosystem service has enormous potential for human well-being and why this ecosystem service needs to be incorporated in the estimation of the “Blue Economy.”KeywordsDesalinationBlue economyFreshwater crisisClimate changeWaste waterWater scarcityEconomic viabilityCapital costOperation maintenance costSocioeconomic pathway (SSP)GDPEconomic feasibilityFeasibility indexRenewable energyReverse osmosis
Article
Many coral reefs are found in arid and semi-arid regions that often face severe water scarcity and depend on seawater desalination for freshwater supply. Alongside freshwater production, desalination plants discharge brine waste into the sea. Brine includes various chemicals (e.g., antiscalants) that may harm the coastal environment. Although widely used, little is known about the ecotoxicological effects of antiscalants (AS) on hard corals. This study compared the impacts of polyphosphonate-based and polymer-based ASs on the coral Montipora capricornis. After two weeks of exposure, we determined the effects of AS on coral physiology, symbiotic microalgae, and associated bacteria, using various analytical approaches such as optical coherence tomography, pulse amplitude modulated fluorometry, and oxidative stress biomarkers. Both ASs reduced polyp activity (∼25%) and caused tissue damage (30% and 41% for polymer and polyphosphonate based AS, respectively). In addition, exposure to polyphosphonate-based AS decreased the abundance of endosymbiotic algae (39%) and upregulated the antioxidant capacity of the animal host (45%). The microalgal symbionts were under oxidative stress, with increased levels of antioxidant capacity and oxidative damage (a 2-fold increase compared to the control). Interestingly, exposure to AS enhanced the numbers of associated bacteria (∼40% compared to the control seawater) regardless of the AS type. Our results introduce new insights into the effects of brine on the physiology of hard corals, highlighting that choosing AS type must be examined according to the receiving ecosystem.
Article
Energy crises caused some secondary challenges in the field of water and food as well its inherent catastrophes. In the nexuses of water and energy, supplying the power for desalination and water treatment process is assumed as an important subject in scientific communities. While, in sunny arid and semi-arid climates (Zahedan, Iran), the application of solar irradiances can convert threats into opportunities. In the present research, in the first step, all operational features in photovoltaic facilities are optimized by Central Composition Design (CCD) as a Response Surface Methodology (RSM) method. In the second step, harvested renewable energy values, carbon emission prevention, initial cost, and maintenance for each year are predicted as per operational factors of the photovoltaic system, which are utilized in the desalination process and with the application of Gaussian Processes, Multilayer Perceptron, Support Vector Machine for Regression (SMOreg) and Polynomial Trees (M5P) algorithms. Finally, in the managerial insight section of the research, an integrated Reverse Osmosis-Photovoltaic system is presented as a green facility of water providing in arid and semi-arid climates. Based on RSM system the main effective factors for energy production, prevention carbon emission (25 year), initial and maintenance costs are Pitch degree (P) (P-value < 0.0001), Pitch degree (P-value < 0.0001), Cross Distance (CD) (P-value < 0.0001), and Panel Capacity (PC) (P-value = 0.0002), respectively. Finally, an SDGS assessment is performed in this investigation, and some managerial insights are proposed. In the different steps of this study, both carbon emission values and cost functions are optimized. While, to the prediction of available solar energy, Gaussian process with more than 0.98 has the most efficiency.
Article
Polybenzimidazole (PBI) was modified by marrying N-substitution with chlorination in order to improve its desalination properties. Based on the solution-diffusion theory, the effect of N-substitution and then chlorination on the water/salt transport properties of PBI was systematically analyzed. Although the introduction of hydrophobic p-toluenesulfonyl groups decreases water sorption, significantly increases water diffusion by weakening the hydrogen bonding between polymer chains. As a result, the water permeability of substituted PBI (SPBI) was 20 times higher than that of PBI. In terms of salt transport, the increase in salt diffusion of SPBI caused by the weaker inter-chain interactions was offset by a substantial decrease in salt sorption due to the combined effect of electrostatic repulsion and increased accessibility of hydrophilic groups to bind water, leading to equivalent salt permeability of PBI to SPBI. Controlled chlorination of SPBI under acidic conditions can further improve polymer water diffusion and thus water/salt diffusivity selectivity. The permeation of both SPBI and chlorinated SPBI is diffusion dependent. Therefore, combining N-substitution and chlorination is an effective strategy to simultaneously improve PBI permeability and water/salt selectivity for desalination applications.
Article
Seawater desalination is applied worldwide as a solution to water supply, especially for countries with limited water resources. The industry sector is the primary water user in varying qualities for different purposes. Desalination of seawater is increasingly implemented in the Persian Gulf region, but the environmental impacts have not been adequately assessed. This study assessed the life cycle environmental impacts of potable and industrial grade water with the most detailed inventory, including the impact of the brine rejected to the sea and solid wastes using SimaPro software. The 18 ReCiPe midpoint H impact categories, three endpoint damage categories, and the single score have also been specified. The seawater reverse osmosis powered by fossil fuels was studied to produce potable and industrial water. Electricity has the highest contribution to most of the studied impact categories. The sensitivity analysis showed that a 10% decrease in electricity consumption could reduce fossil resource scarcity and global warming by about 5% for potable and industrial water. The single total score for Sea water reverse osmosis (SWRO) potable and industrial water production are 98.83 and 168.54 mPt, respectively, mainly related to the human health damage category. The cumulative energy demand assessment showed that non-renewable biomass and renewable (wind, solar and geothermal) have the least energy intensity, respectively. To the best of our knowledge, the life cycle assessment of SWRO industrial water production has not been performed before. The current study would be a baseline for further comparisons. The potable water production results agree with the other studies despite having a much more detailed inventory.
Article
Many of the dramatic changes across the planet during the Anthropocene Epoch cannot be reversed within our lifespans, so it becomes imperative to adapt to change as far as possible. According to the IPCC, adaptation is ‘the process of adjustment to actual or expected climate and its effects. In human systems, adaptation seeks to moderate or avoid harm or exploit beneficial opportunities. In some natural systems, human intervention may facilitate adjustment to expected climate and its effects’ (1, p. SPM 5). While this definition refers only to climate, the context in which adaptation has been most thoroughly considered, the concept of adaptation is applicable to the full range of planetary changes. As implied by the IPCC definition, an adaptation action might be taken proactively, to reduce harm in advance of an impact, or reactively, in response to a perceived or real health risk.
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Thermal energy storage (TES) technology makes concentrated solar power (CSP) technology superior to photovoltaics and wind energy, by making it capable of generating electricity around the clock. The advantage lies in less expensive storage in the form of thermal energy, compared with the expensive storage of electrical energy in batteries. This chapter covers the working principles of CSP by demonstrating the current state of the art of its primary components and the way forward to the next generation of technology. The focus of the chapter lies on molten salts as heat transfer fluid as well as TES material, their chemistry, advancements, and challenges. All components of the chapter are covered within the framework of molten salt technology.
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Water temperature as a key indicator of river environments evolves dynamically as well as stochastically. We introduce a new mathematical framework for modeling river water temperature at an observation station based on a Volterra process: a non-Markovian model. The non-Markovian nature arises from a non-exponential autocorrelation function, which is effectively captured by a completely monotone kernel. Parameters of the model are identified for a study site in Japan where the water temperature has been measured at a 10-min interval. We show that the observed time series of the water temperature is separated into seasonal and stochastic parts, and that the non-exponential autocorrelation function is fitted well by the proposed model. A brief application of the model to statistical evaluation of the river water temperature subject to misspecification is finally presented.KeywordsRiver water temperatureMarkovian liftModel identification
Article
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Solar steam generation is an efficient way to address global freshwater shortages. However, water evaporation suffers from either inefficient heat conduction or relies on expensive materials and complex equipment. Herein, a porous hydrogel (AC‐H) with molecular meshes, micron channels, and internal gaps is fabricated and used for metal ion adsorption. AC‐H exhibits excellent uptake ability and can attain the levels required by industrial water safety standards. Subsequently, the exhausted AC‐H hydrogel is vulcanized in situ (AC‐MS) and upcycled for solar steam generation resulting in ≈1.41 kg m⁻² h⁻¹ evaporation rate under one sun irradition, which reduces costs and converts the waste into a resource. Furthermore, a heat management strategy is developed where a cold surface of specific area is introduced between the AC‐MSx and bulk water to adsorb the heat loss. When the cold area is increased, the energy in the bulk water can be extracted by the coldsurface. which enhances the water evaporation rate. Significantly, the theoretical simulations are in good agreement with the experimental results. Therefore, this research provides a novel strategy to upcycle exhausted materials for photothermal technologies and reduces the heat conduction during solar‐to‐thermal evaporation.
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Qatar is considered one of the most highly water stressed countries in the world, with little in the way of natural water resources. It is almost entirely reliant on the desalination of seawater to provide for municipal and industrial needs, while the growing agricultural sector has historically been dependent upon the desalination of brackish groundwater. This chapter outlines the sustainability initiatives, national strategies, policy instruments, and drivers for efficiency improvements in the water sector in Qatar. The Qatar National Vision 2030 has a particular focus on reducing consumption, improving conservation, and on the circular water economy, highlighting the value of research, development, and innovation (RDI) in implementing the Sustainable Development Goals (SDGs). Significant investment has taken place toward developing a sustainable water industry, where a transition toward renewable energy resources can support desalination, wastewater treatment, and reuse policies for a sustainable Qatar.
Article
The membrane distillation (MD) systems integrated with photovoltaic/thermal (PV/T) collectors can hardly obtain large permeate flux and favorable electrical performance simultaneously. Therefore, an innovative hybrid nanofluid filtered concentrating PV/T (CPV/T)-direct contact membrane distillation (DCMD) system is proposed. The novelty is that Ag/saline water nanofluid acts as a multifunctional fluid capable of absorbing solar spectrum, which cannot be efficiently utilized by solar cells, and converting it into heat to directly produce water in DCMD. Mathematical models of both nanofluid filtered CPV/T and DCMD are established to evaluate the system performance. Results indicated that nearly 70% of solar radiation is converted into useful energy by the nanofluid filtered CPV/T device. Besides, detailed parametric studies are performed to explore how the system performance is affected by the operation and design parameters. It is found that Ag/saline water nanofluid can be heated to 353 K for desalination, at which, the DCMD module can produce 26.4 kg m⁻² h⁻¹ of fresh water. Meanwhile, the electrical efficiency of the system is 12.2% and the equivalent system thermal efficiency can reach a maximum of 71.3%. Furthermore, we demonstrate that the use of Ag/saline water nanofluid as feed stream can mitigate the temperature polarization and improve DCMD performance.
Article
Full-text available
This research paper presents a review of the state of the art of desalination in Mexico, with the aim of clarifying the main challenges and opportunity areas for desalination as the main solution to overcome water stress. First, the current situation and forecasts on the availability of water resources in Mexico are described, followed by the main economic, social, and legislative issues of desalination. Mexico’s installed capacity for the different desalination technologies and their evolution in recent years was investigated, followed by a comparison with global trends. The current state of research and development in desalination technologies carried out by Mexican institutions was also studied. The results show that membrane technology plants account for 88.85%, while thermal technology plants account for the remaining 11.15%. Although Mexico presented a 240% increase in its desalination capacity in the last 10 years, it has not been enough to overcome water stress, so it is concluded that in the future, it is necessary to increase its capacity in greater proportion, specifically in the areas with greater scarcity, which can be achieved with the joint participation of academy–industry–government through the creation of autonomous organizations, social programs, and/or public policies that promote it.
Article
The coupled demister with directing and the perforated plate was proposed in this work, which was applied in the fine droplets removal process for the multistage flash (MSF) desalination process. The performance was evaluated with three criteria, overall particle removal efficiency, pressure drop, and impact factor. The results show that the main influencing factors of the performance of the directing plate mist eliminator are the directing plate length, the installation upper wall angle, and the installation position. The interaction effects occur while two individual directing plates are installed. For improving the fine droplets removal performance, perforated and directing plate coupled mist eliminator was designed, and the results show that the coupled mist eliminator has the best performance compared to the others. The particle separation efficiency is significantly improved, and the efficiency can reach >93.75 %, Euler number is only 5.54, compared to individual structural design, the pressure drop declined and particle removal efficiency increased significantly. Besides, the coupled mist eliminator has a simple structure and can be processed by integrated technology. All these advantages make the directing and perforated plate coupled mist eliminator a promising candidate for fine droplet removal in the MSF desalination process.
Article
In the modern era, deep learning (DL), and machine learning (ML), have emerged as potential technologies that are widely applied in the fields of science, engineering, and technology. These tools have been extensively used to optimize seawater desalination and water treatment processes to achieve efficient performance. Indeed, automation has played a key role in redefining the issues of water treatment and seawater desalination. Artificial intelligence (AI) has been developed as a versatile tool for processing data and optimizing smart water services while addressing the issues of monitoring, management, and labor costs. Recently, specific AI tools, such as artificial neural networks (ANNs) and genetic algorithms, have been implemented for self-monitoring and modeling applications in the field of water treatment and seawater desalination. In the present article, the application of AI in the water treatment and seawater desalination sectors is thoroughly reviewed. Additionally, conventional modeling approaches are compared with ANN modeling. Furthermore, the challenges and shortcomings are discussed, along with future prospects. Moreover, the applications of AI mechanisms in data processing, optimization, modeling, prediction, and decision-making during water treatment and seawater desalination processes are underscored. Finally, innovative trends in seawater desalination and water treatment with AI tools are summarized.
Article
The paper reports pervaporation desalination performance of graphene oxide (GO) membranes for salts solutions. Asymmetrical membranes consisting of GO layer (~5 μm) on polyethersulfone supports prepared via pressure-assisted filtration were utilized in the experiments. The initial performance of membranes attaining 27 kg·m⁻² h⁻¹ for pure water feed at 80 °C is substantially suppressed with pervaporation from salts solutions down to ~4.5 kg·m⁻² h⁻¹ at 0.6 M NaCl concentration. Salts rejection exceeds 99.9 %. According to in-situ and in-operando X-ray scattering study the interlayer distance of GO seriously expands upon ions absorption (up to 5 wt%), varying from 1.45 to 2.67 nm for different cations. The decrease of water permeance, despite of increasing width of the nanochannels, is revealed to originate from increasing activation energy of water molecules transport and diminution of the free volume available for diffusion by >50–80 %. Thus, dynamically changing interlayer distance and loading of graphene oxide with ions are considered the key factors governing the membrane performance. The intercalation of carbon-based spacers (nanoribbons and fullerenols) into interlayer space can be utilized to improve membrane performance. This increases the permeate flux by 70 % compared to pristine GO membranes.
Article
In this study, reverse osmosis brine (ROB) and sodium aluminate (NA) were used as mix water and an activator for ground granulated blast furnace slag (GGBFS), respectively, to investigate the hydration reaction and mechanical properties of the GGBFS. Samples with NA alone and a combination of NA and 5% and 10% CaO were fabricated using tap water (TW) and ROB as mix water. The addition of CaO enhanced the effect of the NA activator in increasing the strength of the samples. With the NA–CaO combination, TW samples promoted the formation of C2ASH8 and C3AH6 phases more than the ROB samples. In the ROB samples, Friedel’s salt was formed. The strength of the TW samples was lower than that of the ROB samples, attributed to the abundantly formed C3AH6 phase in the TW samples. The NA–CaO–ROB samples improved the chloride ion adsorption capacity by increasing the Ca/Si ratio of the hydration reactant. However, in the ROB samples, Friedel's salt was decomposed due to carbonation by air exposure, increasing the concentration of chloride ions in the pore solution and promoting calcite formation. The NA–CaO–ROB samples confirmed the effectiveness of NA as a new GGBFS activator and the potential of ROB as a building material.
Article
Adsorption desalination is a novel technology to supply high-quality potable water driven by a low-temperature heat source. However, only a few composite sorbents, whose excellent performances have been demonstrated in other adsorption-based systems, have been applied in adsorption desalination (AD) systems. This study evaluated the performances of LiCl-silica gel (30 % wt) composite in a lab-scale AD system, realized by packing the sorbents beads inside a finned flat-tube heat exchanger. For the first time, the ad/desorption dynamics under various operating conditions were measured using a T-LTJ (thermal-large temperature jump) apparatus, which has not been employed for evaluation of desalination prototypes so far. The sorption dynamics was compared with silica gel, which is a standard material for AD systems. Results were used to calculate the maximum specific daily water production (SDWP) and optimized cycle time. Moreover, three design strategies of the AD system were proposed, including 2-beds, 3-beds and 4-beds. The 3-beds-configuration was selected for the composite sorbent, being able to reach an SDWP as high as 69 m³/tonne/day under the condition of Teva/cond = 20 °C and Tde = 80 °C. The optimized cycle time is dependent on operating conditions, varying in the range of 240–470 s.
Article
Increasing water scarcity in the face of climate change has driven significant interest in finding low-carbon-intensity ways of generating fresh water from saline sources. Conventional membrane and thermal desalination techniques require large energy inputs that can become prohibitive as salinity increases. Alternatively, solar desalination is a well-developed passive evaporative approach but is limited seasonally and geographically by solar insolation. Here, we propose and demonstrate a passive approach to a more thermodynamically attractive phase change that can also enable desalination: freezing. We develop a system that uses passive radiative cooling to the ultimate heat sink, outer space, to freeze and desalinate salt water. We experimentally demonstrate the passive desalination of 37.3 g/L salt water to 1.88 g/L after two radiative cooling-driven freezing desalination stages with 50% recovery and 17.5 g/L salt water to 0.7 g/L with 65% recovery. Our results highlight the potential of harnessing untapped thermodynamic resources for water technologies.
Article
Adsorption desalination is prescribed as a promising and eco-friendly solution for mitigating water scarcity, owing to its utilization of low-grade thermal waste and zero liquid brine discharge. The keystones that regulate the performance of the adsorption desalination system (ADS) include nature of adsorbents, system design, and operating conditions. The present study aims to provide a state of the art review on the keystones of ADS. Metal-organic frameworks (MOFs) hold remarkable adsorption capacity and tunable structure. However, hydrothermal instability, high cost, and complex synthesizing procedures are the potential challenges that need to be addressed. The technological advancements in ADS have been classified into: (i) Conventional Approach, (ii) Heat and Mass Recovery Approaches, (iii) Hybridization Approaches, (iv) and Adsorbent Substituting Approach. The study provides critical insight and compares the performance of each approach based on specific daily water production (SDWP), specific cooling power (SCP), and coefficient of performance (COP). The conventional ADS produce SDWP of 4.7 m3/ton/d, however producing zero and/or minimal SCP while using payable energy of 1.50 kWh/m3. In heat/mass recovery approaches, pressure equalization-valve delay schemes and master–slave configuration provide ∼ 5 % additional water adsorption/desorption on/from silica-gel and reduce ∼ 50 % thermal heating load, respectively. Evaporator-condenser amalgamation emphasizes the evaporator temperature of 30–42 °C leading towards ∼ 69 % higher SDWP with zero SCP. Dual stage, multi evaporators/condensers scheme is found supportive in cogenerating feature of ADS thereby improvising COP to ∼ 0.87. In hybridization approach, ejector integrated ADS produces SDWP of 80 m3/ton and COP of 2.22 using payable energy of 0.92 kWh/m3, however, needs experimental validation. In the adsorbent substituting approach, CPO-27(Ni), Emim-Ac/Syloid 72FP, and composite adsorbent manifest the SDWP to higher levels. The operating conditions are sensitive and need to optimize depending on the configuration of ADS. Possible future research directions may include efficient designing/ sizing of evaporators/ condensers, minimizing the heat and mass transfer resistances in adsorber/desorber reactor, optimize the thickness of the adsorbent layer in heat exchangers, and investigating wide range of adsorbent classes that can be driven with very low regeneration temperature.
Article
The concept of the temporal selectivity breaks the spatial selectivity-based paradigm of permeability and selectivity in membrane separation technology, and its realization can provide simultaneous efficient salt rejection and high permeability with large pores. In this work, a rotating centrifuge model made of porous copper foil covered with porous graphene is designed to explore the possibility to realize the temporal selectivity on a porous composite graphene‑copper membrane (GCuM) in a molecular dynamics study. The results show that the permeability of porous rotating GCuM increases up to 156 L/cm²/day/MPa with a salt rejection larger than 90 %, which is 2.6 to 1000 times larger than the commercial and other advanced reverse osmosis membranes. The boundary slip velocity between the seawater-GCuM interface inhibits the passage of salt ions, resulting in high salt rejection even in the case of 2–4 nm diameter pores. The stability of the ionic hydration shell and the energy barrier of the ions passing through the pores increase with the increase of the angular velocity, which explains the influence of the boundary slip velocity on the salt rejection from the molecular mechanism. The geometric relation that governs the temporal selectivity principle on porous rotating GCuM has been further derived to explain pore size, membrane thickness, and hydrated ion mass on high permeability and salt rejection. The findings further verify and expand the application scope of the temporal selectivity mechanism, and will promote the application of graphene-based nanoporous centrifuges.
Article
Efficient discrimination of ions and small neutral contaminants remains a challenge for polyamide thin-film nanocomposite (TFN) water separation membranes due to the presence of interfacial defects and particle-agglomeration-induced nonselective voids in the polyamide thin layer. In this work, highly selective TFN membranes were successfully fabricated by leveraging post-synthetic modifications of (3-glycidyloxypropyl)triethoxysilane (GPTES) and trimesoyl chloride (TMC) on MIL-101(Cr)–NH2 MOF filler nanoparticles. GPTES modification suppresses particle agglomeration during interfacial polymerization for membrane formation by forming a stable particle suspension in the organic monomer solution, while TMC-induced in situ chemical crosslinking between filler particles and polyamide addresses the phase compatibility and interfacial issues at the filler–polyamide interface. The resulting TFN membranes show high NaCl, MgCl2, Na2SO4, and MgSO4 rejections of 99.0–99.6% at 150 psi with a water permeance of 1.3 L m⁻² h⁻¹ bar⁻¹. Compared to the thin-film composite (TFC) control membrane, the incorporation of the MOF particles yields a 53.0% and 24.5% increase in water permeance and NaCl rejection. Importantly, the TFN membranes also exhibit excellent rejections to small neutral contaminants such as PEG200 (99.2% rejection) and boric acid (89.0% rejection at a pH value of 7.5) at a relatively low pressure of 150 psi, which is higher than the respective value obtained by the commercial Dow SW30XLE TFC control membrane at the same conditions. The outstanding long-term performance stability revealed the robust structure of the MOF TFN membranes. Our results demonstrate a facile strategy to effectively control particle agglomeration and interfacial defects in polyamide TFN membranes by manipulating the surface chemistry of the filler nanoparticles, which can be applied to the fabrication of effective TFN membranes with molecular level size-exclusion selectivity.
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Energy and water have been fundamental to powering the global economy and building modern society. This cross-disciplinary book provides an integrated assessment of the different scientific and policy tools around the energy-water nexus. It focuses on how water use, and wastewater and waste solids produced from fossil fuel energy production affect water quality and quantity. Summarizing cutting edge research, it describes the scientific methods for detecting contamination sources in the context of policy and regulations. The authors highlight the growing evidence that fossil fuel production, from both conventional and unconventional sources, leads to water quality degradation, while regulations for the water and energy sector remain fractured and highly variable across and within countries. This volume will be a key reference for scholars, industry professionals, environmental consultants and policy makers seeking information on the risks associated with the energy cycle and its impact on the environment, particularly water resources.
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Developing technical alternatives to increase the volume of remediated waters is a promising way to alleviate pressure on natural water basins. However, the extra energy consumed in Wastewater Treatment Plants (WWTPs), mainly powered by fossil fuels, hampers this strategy. This work focuses on promoting efficient upgrading alternatives of treated waters by recovering energy within the treatment process. The approach consists on the recovery and integration of Salinity Gradient Energy (SGE) generated from the contact between SWRO brines and reclaimed wastewaters in reverse electrodialysis modules. The analysis of opportunity of implementing integrated processes in Spanish WWTPs near SWRO desalination plants is tackled. 16 SWRO-WWTP pairs have been inventoried, 10 of them located in Jucar and Segura river basins, hot spot areas for water reclamation. A gross power density of 0.46 W/m² (71 Wh/m³ reclaimed water) of SGE has been generated in the contact between SWRO brines and reclaimed wastewater, increased up to 0.23 kWh/m³ in the most favourable scenario. Estimates of freshwater withdrawals savings up to 434,387 m³/day within the selected installations are obtained. Decrease in water abstraction and integration of renewable source of energy in the remediation process will contribute to water sources protection and water industry decarbonisation.
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Desalination permits the use of brackish and saltwater for different activities. This work aimed to characterize the desalination systems of 31 rural communities in the Brazilian semi-arid region, evaluating the potential of using brackish waters. The physical-chemical characteristics of the groundwater and the concentrate were used to determine the quality indexes for irrigation and animal watering. Most (58%) of the wells had chlorinated sodium water with corrosive tendencies. Among the parameters evaluated, conductivity, sulfate, and magnesium were more related to changes in water quality for animal watering. Chloride, sodium, and conductivity were the parameters that most distanced themselves from the recommended limits for irrigation. A high percentage of the well waters (51%) and brackish waste (65%) it's classified with a bad quality for plant cultivation. Conversely, most of the groundwater (87%), and the brackish waste (71%), integrated the best quality classes (excellent and good) for animal production. Despite the high variability of the quality of brackish waters in the region, it is possible to use this resource, as well as the by-product of desalination, by applying adequate management and appropriate technologies.
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Fog water collection is an emerging opportunity to combat local water shortages in water-scarce areas where sustainable access to water is unreliable, but fog events are frequent. Since fog water systems are implemented within or near communities, they eliminate or decrease the need to travel far distances for the collection of water during times of scarcity. As a result, these systems decrease the physical and social burden of water collection on women and girls, who are the primary water gatherers in most traditional communities. This is an important outcome because women and girls are disproportionately affected by water scarcity and are not seen as equals in water management, access, or control. This paper illustrates how several fog water collection projects have shown, empirically, that the positive outcomes for women and girls may include the freeing of time for domestic and educational pursuits, improved health outcomes, and improved perceptions of self and others’ perceptions of women. These findings are important at a time when the world at large is addressing the Sustainable Development Agenda, where Sustainable Development Goal (SDG) 6 necessitates safe water and sanitation for all and SDG 5 ensures gender equality to empower all women and girls.
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The Sustainable Development Goal (SDG) 6, calling for access to safe water and sanitation for all by the year 2030 supports the efforts in water-scarce countries and regions to go beyond conventional resources and tap unconventional water supplies to narrow the water demand-supply gap. Among the unconventional water resources, the potential to collect water from the air, such as fog harvesting, is by far the most under-explored. Fog water collection is a passive, low maintenance, and sustainable option that can supply fresh drinking water to communities where fog events are common. Because of the relatively simple design of fog collection systems, their operation and maintenance are minimal and the associated cost likewise; although, in certain cases, some financially constrained communities would need initial subsidies. Despite technology development and demonstrated benefits, there are certain challenges to fog harvesting, including lack of supportive policies, limited functional local institutions, inexpert communities, gender inequality, and perceived high costs without undertaking comprehensive economic analyses. By addressing such challenges, there is an opportunity to provide potable water in areas where fog intensity and duration are sufficient, and where the competition for clean water is intensifying because water resources are at a far distance or provided by expensive sources.
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Purpose of Review In the face of rising water demands and dwindling freshwater supplies, alternative water sources are needed. Desalination of water has become a key to helping meet increasing water needs, especially in water-stressed countries where water obtained by desalination far exceeds supplies from the freshwater sources. Recent Findings Recent technological advancements have enabled desalination to become more efficient and cost-competitive on a global scale. This has become possible due to the improvement in the materials used in membrane-based desalination, incorporation of energy-recovery devices to reduce electricity demands, and combining different desalination methods into hybrid designs. Further, there has been a gradual phasing-in of renewable energy sources to power desalination plants, which will help ensure the long-term sustainability of desalination. However, there are still challenges of reducing energy demands and managing waste products from the desalination to prevent adverse environmental effects. Summary This article reviews the history, location, components, costs, and other facets of desalination and summarizes the new technologies that are set to improve the overall efficiency of the desalination process.
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Brine disposal is a major challenge facing the desalination industry. Discharged brines pollute the oceans and aquifers. Here is it proposed to reduce the volume of brines by means of evaporative coolers in seawater greenhouses, thus enabling the cultivation of high-value crops and production of sea salt. Unlike in typical greenhouses, only natural wind is used for ventilation, without electric fans. We present a model to predict the water evaporation, salt production, internal temperature and humidity according to ambient conditions. Predictions are presented for three case studies: (a) the Horn of Africa (Berbera) where a seawater desalination plant will be coupled to salt production; (b) Iran (Ahwaz) for management of hypersaline water from the Gotvand dam; (c) Gujarat (Ahmedabad) where natural seawater is fed to the cooling process, enhancing salt production in solar salt works. Water evaporation per face area of evaporator pad is predicted in the range 33 to 83 m 3 /m 2 ·yr, and salt production up to 5.8 tonnes/m 2 ·yr. Temperature is lowest close to the evaporator pad, increasing downwind, such that the cooling effect mostly dissipates within 15 m of the cooling pad. Depending on location, peak temperatures reduce by 8-16 °C at the hottest time of year.
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The act of ensuring freshwater is considered the most essential and basic need for humanity. Although the planet is water-rich in some terms, the freshwater sources available for human consumption and beneficial uses are very limited. Excess population growth, industrial development coupled with improving living standards have caused an unprecedented need for freshwater all over the world. Regions once rich in water resources are struggling to meet the ever increasing demands in recent years. In addition, climate change and unsustainable management practices have led to a situation called “drought” in many regions. Water supplies in drought conditions can be addressed by taking two major approaches related to management and technology development. The management approaches include demand mitigation and supply enhancement. Demand mitigation can be done by implementing water conservation practices, and by enforcing a mechanism to influence user-responsible behavior through higher water fares and other billing routes. Supply enhancement can be achieved by utilizing the methods available for water reclamation, reuse and recycle including rain harvesting. This paper provides a critical insight of the causes for drought and the issues caused by persistent drought conditions followed by discussion of management and technological approaches required to maintain adequate water resources around the world. Challenges and opportunities involved in implementation of desalination and water reuse technologies in addressing global water scarcity are discussed in detail with case studies
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Quality requirements for water differ by intended use. Sustainable management of water resources for different uses will not only need to account for demand in water quantity, but also for water temperature and salinity, nutrient levels and other pollutants.
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Target 6.4 of the recently adopted Sustainable Development Goals (SDGs) deals with the reduction of water scarcity. To monitor progress towards this target, two indicators are used: Indicator 6.4.1 measuring water use efficiency and 6.4.2 measuring the level of water stress (WS). This paper aims to identify whether the currently proposed indicator 6.4.2 considers the different elements that need to be accounted for in a WS indicator. WS indicators compare water use with water availability. We identify seven essential elements: 1) both gross and net water abstraction (or withdrawal) provide important information to understand WS; 2) WS indicators need to incorporate environmental flow requirements (EFR); 3) temporal and 4) spatial disaggregation is required in a WS assessment; 5) both renewable surface water and groundwater resources, including their interaction, need to be accounted for as renewable water availability; 6) alternative available water resources need to be accounted for as well, like fossil groundwater and desalinated water; 7) WS indicators need to account for water storage in reservoirs, water recycling and managed aquifer recharge. Indicator 6.4.2 considers many of these elements, but there is need for improvement. It is recommended that WS is measured based on net abstraction as well, in addition to currently only measuring WS based on gross abstraction. It does incorporate EFR. Temporal and spatial disaggregation is indeed defined as a goal in more advanced monitoring levels, in which it is also called for a differentiation between surface and groundwater resources. However, regarding element 6 and 7 there are some shortcomings for which we provide recommendations. In addition, indicator 6.4.2 is only one indicator, which monitors blue WS, but does not give information on green or green-blue water scarcity or on water quality. Within the SDG indicator framework, some of these topics are covered with other indicators.
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One of the main concerns in the desalination industry is to relieve pressure on the marine environment caused by brine disposal. Its impact depends on effluent dilution, which may be increased by installing appropriate diffusers. We analysed the environmental effect of brine discharge from two Algerian desalination plants with a similar capacity (200,000 m³/day), but different discharge technology, to explore the reduction in impact on the marine environment by using diffusers. Spatial distribution of the brine was extremely different at the two plants. This was a result of the different discharge technology installed and is reflected in the differences in impact observed on benthic communities. The impact of desalination activity on the marine environment can thus be mitigated and controlled by installation of multiport diffusers. These systems can enhance mixing and reduce the impact on the benthic community and area of influence of facilities as large as those described in this paper.
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Seawater contains large quantities of valuable minerals, some of which are very scarce and expensive in their land-based form. However, only a few minerals, the ones in high concentrations, are currently mined from the sea. Due to recent problems associated with land-based mining industries as a result of depletion of high-grade ores, sustainable water and energy demand and environmental issues, seawater mining is becoming an attractive option. This paper presents a comprehensive and critical review of the current methods of extracting valuable minerals from seawater and seawater brines generated in desalination plants, and suggests ways to overcome some of the limitations and challenges associated with the extraction process. The extraction methods discussed are solar evaporation, electrodialysis (ED), membrane distillation crystallisation (MDC), and adsorption/desorption.
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Desalination of brackish groundwater (BW) is an effective approach to augment water supply, especially for inland regions that are far from seawater resources. Brackish water reverse osmosis (BWRO) desalination is still subject to intensive energy consumption compared to the theoretical minimum energy demand. Here, we review some of the BWRO plants with various system arrangements. We look at how to minimize energy demands, as these contribute considerably to the cost of desalinated water. Different configurations of BWRO system have been compared from the view point of normalized specific energy consumption (SEC). Analysis is made at theoretical limits. The SEC reduction of BWRO can be achieved by (i) increasing number of stages, (ii) using an energy recovery device (ERD), or (iii) operating the BWRO in batch mode or closed circuit mode. Application of more stages not only reduces SEC but also improves water recovery. However, this improvement is less pronounced when the number of stages exceeds four. Alternatively and more favourably, the BWRO system can be operated in Closed Circuit Desalination (CCD) mode and gives a comparative SEC to that of the 3-stage system with a recovery ratio of 80%. A further reduction of about 30% in SEC can be achieved through batch-RO operation. Moreover, the costly ERDs and booster pumps are avoided with both CCD and batch-RO, thus furthering the effectiveness of lowering the costs of these innovative approaches.
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Freshwater scarcity is increasingly perceived as a global systemic risk. Previous global water scarcity assessments, measuring water scarcity annually, have underestimated experienced water scarcity by failing to capture the seasonal fluctuations in water consumption and availability. We assess blue water scarcity globally at a high spatial resolution on a monthly basis. We find that two-thirds of the global population (4.0 billion people) live under conditions of severe water scarcity at least 1 month of the year. Nearly half of those people live in India and China. Half a billion people in the world face severe water scarcity all year round. Putting caps to water consumption by river basin, increasing water-use efficiencies, and better sharing of the limited freshwater resources will be key in reducing the threat posed by water scarcity on biodiversity and human welfare.
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Wastewater need not be disposed to an evaporation basin until all useful benefit has been extracted from the waste stream. Sequential Biological Concentration (SBC) of saline drainage streams offers the ability to create a number of financial opportunities, whilst concentrating the waste stream to a manageable volume. In this paper, we present field data from the first three cells of a six-cell SBC system, to evaluate the potential for sustainable management of saline drainage on irrigated lands. The field data indicate that the progressive increase in salinity can be accommodated by using suitable cropping choices, although yields and hence financial returns could be smaller in the cells with the highest salinity water applications. Significant reductions in other pollutants were achieved during flow through the first cell of the SBC system, with appropriate irrigation and drainage management. In the SBC system we are motivated to grow the highest value crops at the different salinities, provided that adequate yields are maintained. Crop yield levels were maintained up to stage 2 which was irrigated with 3.6 dS/m water, but declined to about half in stage 3 when irrigated with 10.8 dS/m water. Changes in soil profile salinity show that a saline soil was progressively ameliorated due to leaching of the excess salts through provision of a subsurface drainage system and irrigation with 1.2 dS/m water. The SBC stage 1 soil salinity changes were very marked during leaching in the first two years, and very gradual in the subsequent years. A similar pattern of soil salinity changes was observed in the other SBC stages. An advantage of the FILTER type systems over traditional land-based sewage treatment is that the FILTER system can operate without building up salt in the soil profile, and thus ameliorate previously salinised sites not considered suitable for irrigated cropping. The performance of the last three cells of the proposed SBC system has been successfully tested in Australia and overseas. This SBC system with suitable modifications could potentially be used to handle saline drainage from other sources in Australia, such as dry land and urban areas.
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Rapid population growth, climate impediments, poor implementation of regulatory frameworks, and challenging political relations have led to over-exploitation of conventional water resources in the Middle East. This situation may have impelled out-of-the-box thinking and advances in research on non-conventional water resources including desalination, wastewater reuse, rainwater harvesting, and long-distance water transfer. This paper aims to assess the extent of research on non-conventional water resources in the Middle East, and identify original and innovative research findings. Cyprus, Egypt, Israel, Lebanon, the Palestinian Territories, Sudan, Syria, and Turkey were selected for this purpose. A systematic online library search of the scientific literature was conducted, and relations between national indicators and the number of articles and citations were assessed. There was an increasing trend in the number of articles addressing non-conventional water resources. Desalination was the most popular research topic (44%; 5.4 citations, on average), followed by wastewater reuse (37%; 11.5 citations, on average). Publication of desalination articles has increased significantly since 2001, with a substantial number authored by private companies. Non-conventional approaches include commercial salt production at a desalination plant, the strengthening of wastewater reuse standards based on the adverse effects of long-term reuse, the application of a water-harvesting plough for large-scale rangeland rehabilitation, and the development of a 78-km long under-sea pipeline for water transfer. Research on off-site effects and environmental impacts was lacking. Investment in research capacity, as an element of social capital, can contribute to water resources diversification and sustainable solutions both for water-stressed and more humid countries.
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Desalination of seawater, brackish water, and reclaimed water is increasingly utilized worldwide to augment and diversify fresh water sources. The lack of economically and ecologically feasible concentrate management options, however, is a major barrier to widespread implementation of desalination, in particular at inland sites. This paper critically reviews strategies and technologies for concentrate management, including disposal, treatment, and beneficial use. Development of energy-efficient, cost-effective, and environmentally benign concentrate management systems is critical if desalination is to become a major part of a sustainable water future. This paper examines the limitations and advantages of a range of concentrate management tools, including emerging and novel technologies for minimization of concentrate volume, enhancement of water recovery, removal of organic contaminants, and recovery of valuable products and energy.
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Desalination has been considered as an essential way to solve water stress all over the world. Most of previous studies focused on its environmental impacts, energy consumption and desalination technologies rather than human health. However, the safety of desalinated water remains unclear. This study was undertaken to investigate the knowledge, attitude and practice (KAP) of the residents in an island county in eastern China to desalinated water. Seventeen people working in medical and water industries were recruited, and focus group discussion and in-depth interview were conducted among them. Our results showed that the majority of people interviewed knew the definition and local supply pattern of desalinated water, while some of them showed some concern about the safety and nutrition of desalinated water. Current drinking water standard has no specific item for desalination, so we strongly suggest issuing a standard for desalinated water.
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Cities around the world are struggling to access additional water supplies to support their continued growth because their freshwater sources are becoming exhausted. Half of all cities with populations greater than 100,000 are located in water-scarce basins, and in these basins agricultural water consumption accounts for more than 90% of all freshwater depletions. In this paper we review the water development histories of four major cities: Adelaide, Phoenix, San Antonio and San Diego. We identify a similar pattern of water development in these cities, which begins with the exhaustion of local surface and groundwater supplies, continues with importation of water from other basins, and then turns to recycling of wastewater or stormwater, or desalination of either seawater or brackish groundwater. Demand management through water conservation has mitigated, to varying degrees, the timing of water-system expansions and the extent to which cities rely on new sources of supply. This typical water development pattern in cities is undesirable from a sustainability perspective, as it is usually associated with serious ecological and social impacts as well as sub-optimal cost effectiveness. We highlight case examples and opportunities to invest in water conservation measures, particularly through urban-rural partnerships under which cities work with farmers to implement irrigation conservation measures, thereby freeing up water for ecological restoration and use by cities.
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In recent years, reverse osmosis (RO) has grown as an alternative to traditional potable water sources. A major disadvantage of the RO process is the huge amount of brine and its negative impact as a result of its high salinity. This brine is usually discharged to inland water bodies or to the sea and constitutes a threat to ecosystems and species, such as Posidonia oceanica in the Mediterranean Sea; thus, further research is needed for introducing environmentally friendly and economically viable management options for RO brines. This paper gives an overview of recent research as well as different technologies available at several scales to overcome the environmental problems and evaluate profitability related to discharge of RO concentrates. The treatment options have been classified into four different groups according to their final purpose: 1) technologies for reducing and eliminating brine disposal, 2) technologies for commercial salt recovery, 3) brine adaptation for industrial uses and 4) metal recovery. Solar evaporation, two-stage reverse osmosis, electrodialysis, integrated processes and brine adaptation for the chlor-alkali industry are some of the topics that this paper deals with. In the conclusion section, all of the technologies are compared emphasizing all their advantages and drawbacks, feasibility and development stage in order to provide a decision tool to select the best technology for each situation.
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Water scarcity severely impairs food security and economic prosperity in many countries today. Expected future population changes will, in many countries as well as globally, increase the pressure on available water resources. On the supply side, renewable water resources will be affected by projected changes in precipitation patterns, temperature, and other climate variables. Here we use a large ensemble of global hydrological models (GHMs) forced by five global climate models and the latest greenhouse-gas concentration scenarios (Representative Concentration Pathways) to synthesize the current knowledge about climate change impacts on water resources. We show that climate change is likely to exacerbate regional and global water scarcity considerably. In particular, the ensemble average projects that a global warming of 2 °C above present (approximately 2.7 °C above preindustrial) will confront an additional approximate 15% of the global population with a severe decrease in water resources and will increase the number of people living under absolute water scarcity (<500 m(3) per capita per year) by another 40% (according to some models, more than 100%) compared with the effect of population growth alone. For some indicators of moderate impacts, the steepest increase is seen between the present day and 2 °C, whereas indicators of very severe impacts increase unabated beyond 2 °C. At the same time, the study highlights large uncertainties associated with these estimates, with both global climate models and GHMs contributing to the spread. GHM uncertainty is particularly dominant in many regions affected by declining water resources, suggesting a high potential for improved water resource projections through hydrological model development.
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Closed Circuit Desalination (CCD™) technology is an emerging platform for reverse osmosis (RO) water treatment and desalination. It lowers the feed pressure requirement, improves the membrane performance, increases the operational flexibility, and eliminates the need for energy recovery devices using only standard RO equipment. For industrial water treatment and brackish water desalination applications, CCD technology achieves maximum recovery in single-stage units while saving energy. Alternately, a CCD unit can be added to a conventional RO process to concentrate brine and raise recovery. Over 97% recovery has been demonstrated in a single-stage operation. The recovery rate of a CCD unit can be adjusted at the control panel without modification of system hardware, limited only by the scaling characteristics of the feedwater. Maximum recovery operation and high flexibility have significant cost-cutting implications for industrial water treatment and inland brackish desalination, where both feedwater supply costs and brine disposal fees can be significant. CCD systems also demonstrate excellent resistance to fouling and scaling. Cross-flow supplied by a circulation pump washes the membranes, and salinity cycling disrupts and greatly reduces the scaling and fouling. Short membrane arrays and high cross-flow allow the CCD process to operate at higher average fluxes than conventional RO processes, without exceeding the membrane manufacturer’s flow or recovery specifications. This paper describes the design and modeling of high-recovery CCD processes and compares the measured and calculated specific energy consumption levels to validate modeling methods and tools. Two brackish water RO cases are considered: one using Desalitech’s seawater reverse osmosis–CCD (SWRO-CCD) process and the other using its hybrid plug flow desalination–SWRO–CCD (PFD-SWRO-CCD) process. CCD systems are compared favorably to conventional RO trains modeled with the same feedwater, high-pressure pumps, and membranes operating at the same average flux and overall recovery percentage.
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The reverse osmosis (RO) brine generated from the Al-Quds University wastewater treatment plant was treated using an epuvalisation system. The advanced integrated wastewater treatment plant included an activated sludge unit, two consecutive ultrafiltration (UF) membrane filters (20 kD and 100 kD cutoffs) followed by an activated carbon filter and a reverse osmosis membrane. The epuvalisation system consisted of salt tolerant plants grown in hydroponic channels under continuous water flowing in a closed loop system, and placed in a greenhouse at Al-Quds University. Sweet basil (Ocimum basilicum) plants were selected, and underwent two consecutive hydroponic flowing stages using different brine-concentrations: an adaptation stage, in which a 1:1 mixture of brine and fresh water was used; followed by a functioning stage, with 100% brine. A control treatment using fresh water was included as well. The experiment started in April and ended in June (2012). At the end of the experiment, analysis of the effluent brine showed a remarkable decrease of electroconductivity (EC), PO43-, chemical oxygen demand (COD) and K+ with a reduction of 60%, 74%, 70%, and 60%, respectively, as compared to the influent. The effluent of the control treatment showed 50%, 63%, 46%, and 90% reduction for the same parameters as compared to the influent. Plant growth parameters (plant height, fresh and dry weight) showed no significant difference between fresh water and brine treatments. Obtained results suggest that the epuvalisation system is a promising technique for inland brine treatment with added benefits. The increasing of channel number or closed loop time is estimated for enhancing the treatment process and increasing the nutrient uptake. Nevertheless, the epuvalisation technique is considered to be simple, efficient and low cost for inland RO brine treatment.
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Hydrological droughts have a diverse range of effects on water resources. Whilst the impacts of drought on water quantity are well studied, the impacts on water quality have received far less attention. Similarly, quantifications of water scarcity have typically lacked water quality dimensions, whilst sectoral water uses are associated with both water quantity and quality requirements. Here we aim to combine these two elements, focussing on impacts of droughts on river salinity levels and including a salinity dimension in quantifications of water scarcity during drought and extreme drought conditions. The impact of historical droughts on river salinity (electrical conductivity (EC) was studied at 66 monitoring stations located across the Southern USA for 2000–2017. Salinity was found to increase strongly (median increase of 21%) and statistically significantly (p ≤ 0.05) during drought conditions for 59/66 stations compared to non-drought conditions. In a next step, a salinity dimension was added to water scarcity quantifications for 15 river basins in Texas. Water scarcity was quantified using data of sector water uses, water availability, river salinity levels and salinity thresholds for sector water uses. Results showed that the dominant factor driving water scarcity highly differed per basin. Increases in water scarcity were further compounded by drought-induced decreases in water availability, increases in sectoral water demands and increases in river water salinity. This study demonstrates that droughts are associated with important increases in river salinity, in addition to reduced water availability, and that both of these aspects should be considered when quantifying water scarcity. Alleviating water scarcity should therefore not only focus on increasing water availability and reducing water demands (quantity aspects), but also on improving water quality.
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Seawater reverse osmosis (SWRO) desalination is expected to play a pivotal role in helping to secure future global water supply. Whilst the global reliance on SWRO plants for water security increases, there is no consensus on how the capital costs of SWRO plants will vary in the future. The aim of this paper is to analyse the past trends of the SWRO capital expenditures (capex) as the historic global cumulative online SWRO capacity increases, based on the learning curve concept. The SWRO capex learning curve is found based on 4237 plants that came online from 1977 to 2015. A learning rate of 15% is determined, implying that the SWRO capex reduced by 15% when the cumulative capacity was doubled. Based on SWRO capacity annual growth rates of 10% and 20%, by 2030, the global average capex of SWRO plants is found to fall to 1580 USD/(m3/day) and 1340 USD/(m3/day) respectively. A learning curve for SWRO capital costs has not been presented previously. This research highlights the potential for decrease in SWRO capex with the increase in installation of SWRO plants and the value of the learning curve approach to estimate future SWRO capex.
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Seawater reverse osmosis (SWRO) desalination discharge brine-waste as part of the process with immediate (short-term) and chronic (long-term) impacts to marine coastal environment. Brine-waste is often denser than the receiving environment, therefore sinks and flows as a saline plume in adjacency to the sea floor. We suggest that the saline flow over the bottom may impose an osmotic stress, and alter benthic heterotrophic microbial diversity, activity and growth. In this study, we examined the short-term (48 h) effects of different salinities on benthic heterotrophic bacteria attached to the sediment at the eastern Mediterranean coast. To this end, 12 cylinders were filled with sediment and incubated in full darkness with rising salinities ranging from 2% to 20% over the ambient levels. During the summer experiments, heterotrophic bacterial abundance has reduced by 60% at salinity levels> 5% above the ambient concentration. Further, bacterial cell specific activity significantly increased following high salinity scenarios. Our experimental results provide the first scientifically- based data on the immediate effects of SWRO brine over benthic heterotrophic bacteria. However, we stress that long-term studies are imperative at the outfall of operating desalination facilities to determine the chronic effects of brine on benthic bacteria.
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In order to counter growing shortages in water supply, there has been an increasing adoption of non-conventional sources, such as desalination. As a matter of fact, the marginal costs of water (i.e., production) or, in a different perspective, the potential and limitations of different technologies, make the use of particular types of desalination methods an increasing possibility. The growing use of hybrid systems highlights the acknowledgment of those technologies as accepted opportunities to diversify water sources, and from a different perspective, render desalination solutions more efficient and effective. Thus, the study of cost determinants which confer a dynamic importance to such technologies is paramount and policy relevant. For that purpose, cost structures and cost determinants were standardized in order to provide guidelines, or a basis, for a suitable cost perception. This paper provides relevant insights of desalination projects’ key factors, and to such an extent, this is a significant contribution. In this analysis, the results achieved compare possible energy solutions, mainly targeting renewable prospects, due to their impact on the total cost of produced water. The economic feasibility of different desalination technologies and energy solutions is also assessed, with a significant focus on possible hybrid possibilities and the site-specificity of such projects, due to their importance and impact on future technology trends and their cost variations.
Conference Paper
The scarcity of fresh water due to the rapid growth of population and industrial activities has increased attention on desalination process as an alternative freshwater supply. In desalination process, a large volume of saline water is treated to produce freshwater while a concentrated brine is discharged back into the environment. The concentrated brine contains a high concentration of salt and also chemicals used during desalination operations. Due to environmental impacts arising from improper treatment of the brine and more rigorous regulations of the pollution control, many efforts have been devoted to minimize, treat, or reuse the rejected brine. One of the most promising alternatives for brine handling is reusing the brine which can reduce pollution, minimize waste volume, and recover valuable salt. Integration of desalination and salt production can be implemented to reuse the brine by recovering water and the valuable salts. The integrated processes can achieve zero liquid discharge, increase water recovery, and produce the profitable salt which can reduce the overall desalination cost. This paper gives an overview of desalination processes and the brineimpacts. The integrated processes, including their progress and advantages in dual-purpose desalination and salt production are discussed.
Article
Brine extraction is a promising strategy for the management of increased reservoir pressure, resulting from carbon dioxide (CO2) injection in deep saline reservoirs. The extracted brines usually have high concentrations of total dissolved solids (TDS) and various contaminants, and require proper disposal or treatment. In this article, first by conducting a critical review, we evaluate the applicability, limits, and advantages or challenges of various commercially available and emerging desalination technologies that can potentially be employed to treat the highly saline brine (with TDS values > 70.000 ppm) and those that are applicable to a ~ 200,000 ppm TDS brine extracted from the Mt. Simon Sandstone, a potential CO2 storage site in Illinois, USA. Based on the side-by-side comparison of technologies, evaporators are selected as the most suitable existing technology for treating Mt. Simon brine. Process simulations are then conducted for a conceptual design for desalination of 454 m³/h (2000 gpm) pretreated brine for near-zero liquid discharge by multi-effect evaporators. The thermal energy demand is estimated at 246 kWh per m³ of recovered water, of which 212 kWh/m³ is required for multiple-effect evaporation and the remainder for salt drying. The process also requires additional electrical power of ~ 2 kWh/m³.
Article
Extraction and concentrating of NaCl from brine were promising technologies to solve the disposition problem of seawater desalination. A novel nanofiltration-electrodialysis (NF-ED) integrated membrane technology was proposed and investigated. The separation of monovalent & bivalent ions and concentrating of solute were realized in NF and ED process, respectively. A kind of NF membrane with high SO42- rejection and common homogeneous ion exchange membrane were investigated. The results showed that the operating pressure and feeding solution concentration have obvious effect on the water permeate flux and ions rejection ratios. Due to the special properties of NF membrane, almost all of the SO42- in the brine was rejected. The rejection of Ca2+ and Mg2+ was 40% and 87%. The concentrations of Ca2+ in permeate were 392 mg/L in a brine-recycle experiment, which induce lower scaling potential when used as the raw water of ED. The highest NaCl concentration in the concentrating cell could be as high as 160 g/L and the NaCl recovery was about 70% after 5 h under 15 V, while total concentration of "impure ions" (K+, Ca2+ and Mg2+) was about 5 g/L. A concept process was also proposed attempting to realize comprehensive utilization of brine.
Article
Increasing water scarcity in arid and semiarid regions is driving the demand for non-conventional water resources in irrigated agriculture. Seawater desalination for sustaining agricultural production is being reported as an alternative water source in some Mediterranean countries. It represents an abundant and steady water source which effectively removes the climatological and hydrological constraints. However, first experiences are highlighting that certain important issues can become a barrier to its spread for crop irrigation. First, the high-energy requirement is still an essential feature of seawater desalination, leading to production costs several times higher than other agricultural water sources. Moreover, the high greenhouse gas emissions linked to the intensive use of energy could exacerbate climate change. Additionally, there are important agronomic concerns related to the lack of desalinated seawater quality standards; which can cause risks for both crop production and the soil environment if not properly managed. Specific quality regulations for desalinated seawater production, blending and management modelling, on-farm technical means and water and soil monitoring may mitigate these risks for crop irrigation. This paper reviews current irrigation experiences with desalinated seawater and analyses the most important questions to be considered, with a particular focus on the agronomical aspects.
Article
Reverse osmosis (RO) is a pressure driven membrane process which has been widely applied and recognized as the leading technology of desalination process. Improvement in RO technology including advanced membrane material, module and process design, and energy recovery has led to cost reduction which in turn gaining interest to its commercial applications. RO is now being used in various applications including selective separation, purification, and concentration processes. In food industry, RO is applied for concentration of fruits and vegetable juices, pre-concentration of milk and whey, and dealcoholization of alcoholic beverage. For area which has large source of natural humic water or peat water, RO can be applied to produce clean water for community water supply. RO was also investigated for organic mixture separation and CO2 regeneration from essential oil extraction using supercritical fluid. The application of RO as a final step of wastewater treatment for water reuse and valuable component recovery seems to be promising in wastewater reclamation. In this paper, the applications of RO, its advantages, and limitations are discussed. In addition, challenges and perspective of RO membranes are pointed out.
Article
Membrane-based technologies have increasingly been chosen in desalination processes, which is evidenced by the increase of large-scale plants constructed in recent years. Indeed, several appropriate strategies should be considered to minimize problems faced during the construction, such as membrane system designs, area requirement, energy requirement, operation and maintenance, and environmental impact, which are related to the economic view and process efficiency. Keep the operating parameters constant during the scale-up of the membrane system should also be an important concern to maintain the performance of the membrane system. In this paper, scale-up strategies for the membrane-based desalination process are reviewed, including desalination technology, economic evaluation, industrial challenges, and scale-up effort. In addition, the opportunity of the integrated membrane system is also emphasized.
Article
In this paper, a review of emerging desalination technologies is presented. Several technologies for desalination of municipal and industrial wastewater have been proposed and evaluated, but only certain technologies have been commercialized or are close to commercialization. This review consists of membrane-based, thermal-based and alternative technologies. Membranes based on incorporation of nanoparticles, carbon nanotubes or graphene-based ones show promise as innovative desalination technologies with superior performance in terms of water permeability and salt rejection. However, only nanocomposite membranes have been commercialized while others are still under fundamental developmental stages. Among the thermal-based technologies, membrane distillation and adsorption desalination show the most promise for enhanced performance with the availability of a waste heat source. Several alternative technologies have also been developed recently; those based on capacitive deionization have shown considerable improvements in their salt removal capacity and feed water recovery. In the same category, microbial desalination cells have been shown to desalinate high salinity water without any external energy source, but to date, scale up of the process has not been methodically evaluated. In this paper, advantages and drawbacks of each technology is discussed along with a comparison of performance, water quality and energy consumption. Copyright © 2015 Elsevier Ltd. All rights reserved.