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Environmental impact of brine disposal on Posidonia seagrasses
Abstract
The location of big SWRO plants is usually limited by environmental restrictions such as the presence of the Posidonia habitat in the Mediterranean coast. The unknown impacts of brine on the flora and fauna associated at sea grasses has caused environmental damages either high cost disposal solutions of doubtful viability. Previous to the construction of 160.000 m 3 /day SWRO Plant in the southeast coast of Spain, an unique research study was carried out in the Mediterranean coast by some of the most advanced Spanish Research Centres in cooperation with two Spanish universities. The knowledge of the Posidonia limits can help not only to locate Desalination plants but to design disposal devices. This paper reports the results of two years study testing the salinity impact on Posidonia habitat lab and field with brine produced with a SWRO pilot plant. Additionally a brine disposal model has been developed to support the design of a full scale disposal system.
... As highlighted by several Spanish studies, P. oceanica is negatively impacted by increased salinity, which manifests itself in significant growth reduction and reduced shoot survival in tank-based experiments [44,45]. However, even though the conclusions are the same, the results of this study (reporting field surveys) are only of limited comparability to the aforementioned studies which report tank-based experiments to which the brine was added. ...
... This may be due to its shallow location, resulting in fast dilution and dispersion of the brine plume combined with high incident irradiance. Also another study highlighted the sensitivity of P. oceanica to desalination brine [45] -while also providing guidance about salinity levels which should not be exceeded for ensuring healthy seagrass meadows in the proximity to outfalls. The same work also included recommendations for designing and placement of brine outfalls. ...
... Mediterranean seagrasses have also been used for assessing benthic marine environmental quality [58][59][60]. In the context of seawater desalination, the issue of brine discharge impacting seagrasses has been explored mostly by a number of Spanish studies conducted in the context of the desalination plants in Alicante [51,56], Blanes [47] and Formentera [45,46,61]. One of these studies [61] also provided guidance for designing brine outfalls in order to reduce impact on benthic communities -specifically, to avoid placing such outfalls close to seagrass meadows or, if this is not feasible, to avoid exceeding salinity levels of 38.5 psu anywhere in the meadow for more than 25% of the observations (on an yearly basis) nor 40 psu in any point of the meadow for more than 5% of observations. ...
Cyprus relies on seawater desalination for a large part of its drinking water supply, with reverse osmosis providing more than 95% of the total desalination capacity in the country. Nevertheless, the environmental impacts of desalination for the Cypriot environment remain poorly understood. Using a combination of mining existing governmental and corporate survey data and reports, this study explores the scale of desalination in Cyprus, the impacts on the coastal marine environment and its overall carbon footprint. Surveys of Posidonia oceanica seagrass meadows show strongly reduced density of shoots and leaf surface area, respectively. Analysis of the available data relating to the overall production of desalinated water and energy consumption reveals that 68.7 million m 3 of desali-nated water were produced in Cyprus in 2017, resulting in the release of 160 ktons of CO 2 equivalent, representing around 2% of the total carbon emissions in Cyprus. The results are directly applicable for understanding the impacts of brine discharge on seagrass meadows, one of the most common types of Mediterranean seabed ecosystems and useful for providing guidance to decision makers as they are striving to achieve a zero-carbon economy. strategies for achieving greater sustainability in terms of reduced CO 2 emissions and less brine discharge are discussed.
... Therefore, predicting how specific stressors interact with seagrasses is essential in their conservation and management (Galli et al., 2017;He and Silliman, 2019;Stockbridge et al., 2020). Warm and highly saline brine discharges from seawater desalination plants in the Mediterranean (Fernandez-Torquemada and Sanchez-Lizaso, 2005;Garrote-Moreno et al., 2014;Latorre, 2005;Xevgenos et al., 2021) are getting more and more common on warm-temperate, often arid coasts around the world. The discharged brine typically has around 44-90‰, depending on the type of plant and desalination technology used (Fernandez-Torquemada and Sanchez-Lizaso, 2011 and references therein) -e.g., for a desalination plant near Alicante, Spain, a brine salinity of 68‰ was reported (Garrote-Moreno et al., 2014). ...
... During heat events in the Mediterranean Sea, especially around noon, the relatively high air temperatures cause high evaporation, resulting in a high salinity in shallow coastal waters, where the seagrasses and C. nodosa thrives. Similar conditions of increased temperature and salinities in the range of those which are applied in this study are likely to occur is that of brine discharge near seawater desalination plants which have been found to impact seagrass meadows (Fernandez-Torquemada and Sanchez-Lizaso, 2005;Latorre, 2005;Xevgenos et al., 2021) including the species studied here (Garrote-Moreno et al., 2014). Seagrasses have developed various physiological strategies to overcome the detrimental effects of high salinity, such as diffusion from the cytoplasmic compartment into the chloroplasts, leading to a decreased efficiency of photosynthesis (Sudhir and Murthy, 2004). ...
The Little Neptune grass Cymodocea nodosa is a key seagrass species in the Mediterranean Sea, forming extensive and patchy meadows in shallow coastal and transitional ecosystems. In such habitats, high temperatures and salinities, separately and in combination, can be significant stressors in the context of climate change, particularly during heatwave events, and seawater desalination plant effluents.
Despite well-documented negative, macroscopic effects, the underlying cellular and molecular processes of the combined effects of increasing temperature and salinities have remained largely elusive in C. nodosa – which are addressed by the present study. High salinity and high temperature, alone and in combination, affected ion equilibrium in the plant cells. Non-synonymous mutations marked the transcriptomic response to salinity and temperature stress at loci related to osmotic stress. Cell structure, especially the nucleus, chloroplasts, mitochondria and organization of the MT cytoskeleton, was also altered. Both temperature and salinity stress negatively affected photosynthetic activity as evidenced by ΔF/Fm’, following an antagonistic interaction type.
Overall, this study showed that all biological levels investigated were strongly affected by temperature and salinity stress, however, with the latter having more severe effects. The results have implications for the operation of desalination plants and for assessing the impacts of marine heat waves.
... The impact on the terrestrial environment caused by seawater desalination includes construction, piping, removal of vegetation, excavations, as well as the noise from the construction activities [13][14][15]. The impact on the marine environment includes seabed digging and piping, long-term pumping, discharge of brine with pre-and posttreatment chemical additives, waste heat, and heavy metals, resulting in changes of salinity and pH [16][17][18], eutrophication, and the accumulation of heavy metals and chemicals that affects the coastal ecology [19][20][21][22]. ...
... However, it is not difficult to find studies showing the impact of salinity on habitats and marine living resources. Latorre tested the impact of brine discharge on sea grass habitats and recommended that discharge ports should be kept far from habitats to avoid adverse effects [16]. Desalination plants have been established all across the coast of the Red Sea. ...
... The whole world's seawater desalination capacity was 4.5 × 10 8 m 3 /day by the end of 2005, and this technology was widely used in the countries in the Persian Gulf, and by the Mediterranean and Red Sea [10]. One concern related to seawater desalination addresses the disposal of the concentrated saline, resulting from seawater desalination, which could cause serious environmental problems in the marine ecosystem [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. However, because the proportion of the constant chemical elements contained in the concentrated saline from seawater desalination and the seawater concentrated saline are almost the same, the usage of the concentrated liquid obtained from seawater desalination for the production of sea salt can be achieved [27]. ...
... The most widely utilized approach is the direct discharge into the sea, which causes a series of problems to the ambient seawater body by its influence on the salinity, temperature, turbidity, dissolved oxygen rates, and metal concentration. The release of concentrated saline with a high salt level, normally twice that of seawater [12,18], would result in dramatic ecological degradation, such as a substantial detriment to sea grass, plankton, invertebrates, and fish [10][11][12][13][14][15]22,25,26]. ...
Landsat images from 1979, 1988, 1999, 2008, and 2013 were used to analyze the landscape area change of salt pans lying on the coast of Tianjin. While initially (1979-1988), the area of Tianjin's salt pan increased, later (1988-2013) it declined dramatically. In the first phase (1979-1988) of the studied period the primary roll-in landscape of the salt pan wasbarren land with an area of 60.0 km2. By 1988, the area of Tianjin's salt pan rose to 457.8 km2. The main roll-out landscape of the salt pan during 1988-2013 was urban, barren land, village/town, harbor, and road whose area amounted to 69.8, 35.9, 27.3, 25.5 and 18.4 km2 respectively. The roll-out barren land will be transformed to construction land ultimately. By 2013, the total loss reached 167.3 km2, which was 36.5% of the salt pan area of Tianjin in 1988. With the development of coastal economy, the salterns with a lower economic value were transformed to and replaced by land use types with a higher economic value. This trend would influence the production of sea salt and the development of sodium hydroxide and sodium carbonate industries. Seawater desalination provides an opportunity for the restoration and compensation of salt production capacity. Based on the theory of circular economy and industrial symbiosis, in this article an industrial symbiosis model for sea salt production and sea water desalination is explored: "mariculture-power plant cooling-seawater desalination-Artemia culture-bromide extraction-sea salt production-salt chemical industry". Through the application of this process sustainable development of the sea salt production in Tianjin could be achieved.
... In general, toxicity will depend on the sensitivity of a species to increased salt levels, its lifecycle stage, the exposure time, and the natural salinity variations of the habitat to which the species is adapted. For instance, salinity tolerance studies of the seagrass Posidonia oceanica in the western Mediterranean showed that a salinity of 43 may reduce growth rates by 50% and that a salinity of 45 may result in 50% mortality within 15 days [86]. These values compare to ambient salinity levels of 37-38 in the western Mediterranean. ...
... Most marine organisms can adapt to minor deviations in salinity and might recover from extreme, short-term exposure to increased salinities. For example, P. oceanica seagrass that survived in a salinity of 43 over 15 days were able to recover when returned to normal conditions [86]. However, only a few species will be tolerant of high salt concentrations over prolonged periods of time, as caused by the continuous discharge of desalination concentrates. ...
... There is a growing interest in understanding the aquatic eco-toxic impact of brine disposal. Many laboratory based studies (Latorre, 2005;Sanchez-Lizaso et al. 2008;Dupavillon and Gillanders, 2009) w a t e r r e s e a r c h 6 1 ( 2 0 1 4 ) 2 1 0 e2 2 3 Gacia et al. 2007;Ruso et al. 2007;Sanchez-Lizaso et al. 2008) report similar findings that indicate brine disposal is a major cause of aquatic eco-toxic impact. It is also recognized that credible and reliable impact estimates for brine disposal are needed, but many early desalination LCA studies simplify the assessment by assuming that the desalination brine is fully diluted before discharge and poses negligible impacts to the aquatic eco-system (Table 1). ...
... The burdens associated with 1 m 3 of produced water from a desalination plant, for instance, are significantly reduced with the development of high-flux membranes and increases in the efficiency of energy supply system. , 2005a, b, c, 2006) Lundie et al. (2004, 2005 Zhou et al. (2013), Norwood and Kammen (2012) w a t e r r e s e a r c h 6 1 ( 2 0 1 4 ) 2 1 0 e2 2 3 3. 3. ...
As concerns of natural resource depletion and environmental degradation caused by desalination increase, research studies of the environmental sustainability of desalination are growing in importance. Life Cycle Assessment (LCA) is an ISO standardized method and is widely applied to evaluate the environmental performance of desalination. This study reviews more than 30 desalination LCA studies since 2000s and identifies two major issues in need of improvement. The first is feasibility, covering three elements that support the implementation of the LCA to desalination, including accounting methods, supporting databases, and life cycle impact assessment approaches. The second is reliability, addressing three essential aspects that drive uncertainty in results, including the incompleteness of the system boundary, the unrepresentativeness of the database, and the omission of uncertainty analysis. This work can serve as a preliminary LCA reference for desalination specialists, but will also strengthen LCA as an effective method to evaluate the environment footprint of desalination alternatives.
... Nevertheless, the large scale application of RO is often questioned for the brine disposal issue and its unfavorable impact on the environment. Unsurprisingly, soon after the extensive application of RO, the contaminations of RO brine on soil, ground water, and marine ecosystem were reported [2,3]. These issues have urged the development and innovation of more sustainable desalination processes with the ultimate aim to maximize the water recovery and the process efficiency. ...
... Nomenclature A 1 ,A 3 outer and inner surface areas of hollow fiber membranes, respectively (m 2 ) C f ,C 1 feed concentrations in bulk and at membrane outer surface (M) C p,f ,C p,d specific heat capacity of feed and distillate solutions, respectively (J 1C À 1 kg À 1 ) D m membrane permeability (m 2 s À 1 ) D m,i ,DD m initial value and reduction of membrane permeability, respectively (m 2 s À 1 ) % Reduction ,% Recovery ratios of membrane permeability reduction and recovery, respectively (%) D m ðtÞ, D m,f , D m,recovery membrane permeability at different times, at completion of MD, and after completion of MD followed by DI water rinsing, respectively (m 2 s À 1 ) D wÀa diffusion coefficient of water vapor through stagnant air (m 2 s À 1 ) D s solute diffusion coefficient (m 2 s À 1 ) D ðhÞ hydraulic diameter of shell side (m) T f ,in ,T f ,out inlet and outlet temperatures of feed stream, respectively (1C) T d,in ,T d,out inlet and outlet temperatures of distillate streams, respectively (1C) T f ,T d logarithm mean temperatures of feed and distillate streams, respectively (1C) T 1 temperature of feed solution at membrane outer surface (1C) T 2 ,T 3 temperatures of distillate solution at interface and membrane inner surface, respectively (1C) T m logarithm mean temperature of inlet and outlet of feed stream (1C) V p ,V total pore and total membrane volumes, respectively (m 3 ) v f ,v d velocities of feed and distillate streams, respectively (m s À 1 ) w 1 ,w 2 dry and kerosene impregnated fiber masses, respectively (kg) Y lm logarithm mean fraction of air in membrane pores ...
We have designed and investigated hollow fiber membranes with various configurations and morphologies for water and salt recovery from highly concentrated sodium chloride (NaCl) via direct contact membrane distillation (DCMD) and crystallization. Three types of membranes were fabricated including single-layer polyvinylidene fluoride (PVDF), dual-layer hydrophobic–hydrophobic PVDF and dual-layer hydrophobic–hydrophilic PVDF/polyacrylonitrile (PVDF/PAN) membranes. Compared to dual-layer membranes, the single-layer PVDF membrane exhibited a superior wetting resistance as evidenced by its highest purity of product water (1.1–1.3 μS cm−1), smallest reduction of membrane permeability (17.7%), and almost complete recovery of membrane permeability after rinsing (99.1%). It was found that membrane pore size and morphology underneath the membrane surface play more important roles to mitigate membrane wetting as compared to membrane wall thickness. As a result, the single-layer membrane possessing a smaller pore size and a cellular mixed-matrix structure outperformed the dual-layer membranes with a globular morphology. The NaCl was recovered from the DCMD retentate solution by means of a cooling crystallizer operated under a batch mode. The supersaturated NaCl ions were uniformly configured into cubical shape crystals. Moreover, preliminary results revealed the feasibility of tailoring the ultimate crystal size distribution (CSD) by adjusting the degree of supersaturation of the crystallized solution through manipulation of the crystallizer cooling profile.
... The survival of seagrass is also sensitive to the salinity of the sea water above [23]. For example, Latorre [24] reported a mortality of 100% for the seagrass with a fifteen-day exposure to 50 psu (practical salinity unit) of salinity, and 50% to 45 psu. Sanchez et al. [25] observed reduced growth and premature senescence of the seagrass with an increase in salinity of 2-3 psu above the ambient level. ...
While the current practice in designing brine outfalls for seawater desalination plants has provided a level of protection to the coastal environment that is deemed acceptable, additional research can be pursued to further improve the state-of-the-art understanding as well as enable the integration of beneficial features introduced by the brine outfall. The present study performed both numerical simulations and laboratory experiments to investigate the mixing and spreading of an 45º inclined dense jet in coastal regions with submerged vegetation canopies at the seabed. The numerical simulations utilized the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-ε turbulence closure and non-interactive species transport model. The experiments were performed using the technique of Planar Laser Induced Fluorescence (PLIF) for verification. The overall results showed that the mixing of the inclined dense jet is enhanced just above the top of the submerged canopy due to the presence of stem-scale wakes and increased dispersity promoted by the spatial inhomogeneity near the canopy interface. A threshold value of 0.6 for the characteristic parameter, ϕFr, where Fr is the densimetric Froude number of jets and ϕ is the canopy density, has been observed above which the dilution coefficients reach a plateau and are no longer influenced by the canopy density. Within the canopy, however, the barrier effect prevails in the mixing process leading to constrained dilution particularly with denser canopies. In particular, the concentration at the impingement region within the canopy near the bottom is observed to increase with the increase in the general canopy density.
... Discharge and dispersion of brine into a receiving body is a commonly used route due to its low costs, but can cause adverse effects on aquatic environments. For example, if the salinity increases above the habitual values of Posidonia oceanica seagrass, its mortality increases and its growth rate reduces [2]. A study monitoring a P. oceanica seagrass meadow under brine discharge impact, showed high epiphyte cover and nitrogen content in the meadow [3]. ...
It is critical that the development of new technologies to solve environmental problems do not shift the burdens (impacts) to other mediums. Therefore, to ensure the optimum environmental design of water treatment and recovery systems, it is pertinent to apply life cycle assessment (LCA) at an early stage of development. Using LCA at an early developmental stage is known as prospective LCA and is particularly challenging due to the low data availability or quality. The aim of this study is to highlight the opportunities and challenges of using prospective LCA in the development of water treatment and recovery technologies. To do this we utilise two case studies from the EU Zero Brine project and apply LCA at two developmental stages. The treatment systems are specifically tailored for each case to treat the individual brine compositions and selectively recover its constituents. The first stage LCAs are based on laboratory experiments and engineering-based calculations, whilst the second stage assessments use improved input data from pilot plants and simulation. The paper compares the analyses of both stages, identifies key differences and discusses these disparities. In addition, it provides insights on the challenges of applying LCA for the design and development of wastewater treatment and recovery systems.
... Moreover, the recovery of magnesium from brines contributes to reduce the environmental impact of these streams [8][9][10], which are typically discharged into natural water bodies. ...
Increasing attention is nowadays paid to the management and valorisation of industrial waste brines aiming also at the recovery of raw materials. Magnesium has been listed as a Critical Raw Material by EU, prompting researchers to investigate novel routes for its recovery. Within this framework, a novel Crystallizer with Ion Exchange Membrane (CrIEM), is proposed as an innovative way to recover magnesium from industrial waste brines exploiting low-cost alkaline reactants. In the present work, a novel mathematical model of the CrIEM process is proposed to provide a useful tool for its design in different working conditions. Batch and feed & bleed continuous configurations have been investigated taking into account: (i) the variation of the alkaline and brine concentration in their own collection tanks over time and (ii) the spatial mono-dimensional (1D) steady-state description of the main phenomena that occur inside the CrIEM. Original experimental data, from ad-hoc laboratory tests, and literature information were used to validate the proposed model both in the batch and continuous feed & bleed configuration. A good agreement between model predictions and experimental/literature data was found for both cases, thus proving the reliability of the proposed model for the design of the CrIEM reactor.
... 7 Particularly, more and more countries have been interested in the implementation of zero liquid discharge policies, which can prevent the negative environmental impacts of brine disposal. 8 Zero liquid discharge systems such as membrane distillationcrystallizers can further regenerate useful feedstocks from brine, like fresh water and valuable metals. 9 MD has been attracting a wider interest with a growing number of research studies on MD technology. ...
The recent attention on perfluorinated superhydrophobic membranes has been accompanied with a growing concerns over the potential degradation of longer than C6-perfluoroalkyl chains containing compounds in the environment to form bioaccumulating perfluoroalkyl acids. In order to keep the perfluorinated surface of the superhydrophobic membranes, we have addressed the problem of bioaccumulation by immobilizing perfluoro-tert-butyl groups to commercially-available aerogels. The resulting fluorous aerogels were electrosprayed on the top of commercial PVDF membranes to fabricate superhydrophobic membranes. The effects of varying the alkyl chain between the aerogel and the perfluoro-tert-butoxy groups as well as the concentrations of the modified aerogel were studied to identify the optimal membrane for membrane distillation (MD). The fabricated membranes were tested for MD performance with sodium dodecyl sulfate (SDS) and saline water (3.5% NaCl). The F1-SiG100 membrane (prepared by grafting 300 mg 1-(nonafluoro-tert-butoxy)-4-butylethoxysilane aerogel on 300 mg PVDF-HFP) exhibited superhydrophobicity (water contact angle=151.2), a very rough surface (Ra=2.17 m), and an extremely low surface free energy (0.82 ± 0.17 mN m1). It also showed high resistance to low surface energy feed up to 0.5 mM SDS and saline water.
... The brine from desalination technologies can be used as a highsalinity solution (HSS) for improved power production from RED [86,87]. At the same time, this approach avoids the environmental hazards of brine discharge [88,89]. The concept of combining RED with desalination technologies has long been proposed [90]. ...
... The reject from the desalination plants were usually 10 to 15 percent more concentrated and at higher temperature than that of seawater (Cipollina et al., 2012). The continuous release of a concentrate, which is characterized by having a higher salinity and/or temperature than that of seawater, will increase the seawater salinity level and could be unsafe for marine life (Latorre, 2005;Peters & Pintó, 2008). Now a days, the mineral extraction from seawater and reject from the desalination plants attracted researchers all over the world due to the benefits in reducing environmental effect and desalination cost as well as diversifying the land mining process (Bazedi et al., 2014;Neilly et al., 2009). ...
Conventional desalination technologies produce a large volume of concentrate known as brine. This brine contains greater concentration of inorganic compounds than that in seawater as well as chemical additives used by the pre-treatment units. The literatures reported that the current disposal options have a number of severe limitations that are associated with technical challenges and environmental issues. As such, research studies have remarkably carried out into the development of mineral extraction processes with aim of producing valuable minerals from brine. This technique may lead to produce high purity of freshwater with the total elimination of waste liquid by converting the effluents into deionised water and a compact solid waste, which contains valuable salts and minerals that can be reprocessed and reused. Therefore, this paper will review different design aspects, cost-effective methods, and parameters affecting solubility and precipitation of different valuable minerals from Reverse Osmosis (RO) brine. Chemical precipitation method was experimentally implemented at Water Research Center (WRC) of Kuwait Institute for Scientific Research (KISR) with aim of extracting valuable minerals, including magnesium, calcium, boron, sulphate, and strontium, from the rejected brine of the main Seawater Reverse Osmosis (SWRO) desalination unit of Desalination Research Plant (DRP). The mineral extraction experiments were performed by using sodium hydroxide as base at different processing temperature and pH. The results showed that more than 90% of magnesium (Mg) was extracted from RO brine at pH 10 and temperature 90°C. Based on the experimental data and mathematical calculations, the production of magnesium oxide from DRP is around 228 ton per year. The mathematical results showed that the annual benefit from magnesium oxide production is 572,010 US$ per year for the aforementioned desalination plant.
... Apart from fossil fuel combustion, many other harmful gases are emitted during the desalination process ultimately impacting the environment. Discharge of the waste stream, consisting of brine (highly saline), also has a potential adverse impact on the marine environment (Latorre 2005). This discharged stream contains residual chemicals from the inlet seawater pretreatment process and metals from corroded equipment. ...
A shortage of freshwater is one of the leading factors restricting sustainable global development. Desalination has evolved to overcome water shortages in many regions since the mid-20th century, especially in North Africa, the Middle East, some states of the United States, and Mediterranean countries. In particular, Middle Eastern countries have established desalination facilities that produce approximately half of the globally desalinated water to secure the future of humanity, and a large percentage of this water comes from thermal desalination. The energy intensive nature of thermal desalination creates significant negative impacts on the environment, which has been poorly understood in many of these countries. Therefore, to quantify the environmental impact in a case study, we selected a small country of the Arabian Gulf, Qatar, which has a total annual desalination capacity of approximately 500 million m³ of which 68% is being produced by multi-stage flash (MSF) thermal desalination. Life cycle assessment (LCA) was employed to quantify the impacts of two different MSF configurations with varying gained output ratios (GORs). Environmental load analysis showed that the plant with the low GOR released a higher amount of CO2 (12. 6 kg) to produce 1 m³ of water while the modified plant with the high GOR released less CO2 (7. 32 kg) per m³ of water. This comprehensive quantitative analysis has a significant regional impact because it has the potential to act as baseline for more sustainable water systems in areas that are highly dependent on MSF desalination for water security.
... The brine from seawater desalination plants that are installed in the coastal areas are commonly discharged back to the sea. The continuous release of rejected brines from desalination plants which is characterized by having a higher salinity and/or temperature than that of feed seawater will increase the seawater salinity level and harm the marine creatures [16,17]. The presence of inorganic compounds and higher salt concentration of the rejected concentrate causes major environmental and regulatory problems for seawater desalination industry [18]. ...
The brine disposal from desalination plants and its environmental impact are the major challenges faced by the desalination industry all over the world. The desalination brine contains higher concentration of inorganic compounds than that in seawater in addition to the chemical additives used by the pre-treatment units. The precipitation of minerals from brine reduces the fresh water production cost as well as minimizes the brine disposal problem. This article explores a systematic approach for the brine treatment problem by assessing the performance of mineral precipitation using chemical precipitation technique for precipitating valuable minerals, including magnesium, calcium, boron, sulfate, and strontium, from the rejected brine of two seawater reverse osmosis (SWRO) desalination plants in Kuwait. The preliminary mineral precipitation results showed that sodium hydroxide is the best suitable base for precipitation of all minerals compared with calcium hydroxide and ammonium hydroxide. Further, the mineral precipitation experiments were performed by using sodium hydroxide as base at different processing temperature and pH. The results showed that more than 78% of magnesium (Mg) was precipitated from RO brine at pH 10 and temperature of 90°C. The preliminary economic evaluation of magnesium oxide production using RO brine of desalination plants at Doha Desalination Research Plant and Shuwaikh sites of Kuwait are 228 and 97,909 tons per year, respectively. Overall, this study established optimum operating condition for effective precipitation of minerals from high saline Arabian Gulf SWRO brine with high efficiency and showed promising results for large-scale mining.
... Highly saline wastewater streams from steel, chemical, petrochemical, and mining industries are of key concern for environmental and economical sustainability in developing countries (Latorre, 2005;Shannon et al., 2008;Bouchrit et al., 2015;Choi et al., 2018;Deshmukh et al., 2018). Therefore, concentrating high salinity liquids has become an important task in water treatment. ...
Scaling in membrane distillation (MD) is a key issue in desalination of concentrated saline water, where the interface property between the membrane and the feed become critical. In this paper, a slippery mechanism was explored as an innovative concept to understand the scaling behavior in membrane distillation for a soluble salt, NaCl. The investigation was based on a novel design of a superhydrophobic polyvinylidene fluoride (PVDF) membrane with micro-pillar arrays (MP-ethod. The membrane showed a contact angle of 166.0 ± 2.3° and the sliding angle of 15.8 ± 3.3°. After CF4 plasma treatment, the resultant membrane (CF4-MP-PVDF) showed a reduced sliding angle of 3.0o. In direct contact membrane distillation (DCMD), the CF4-MP-PVDF membrane illustrated excellent anti-scaling in concentrating saturated NaCl feed. Characterization of the used membranes showed that aggregation of NaCl crystals occurred on the control PVDF and MP-PVDF membranes, but not on the CF4-MP-PVDF membrane. To understand this phenomenon, a "slippery" theory was introduced and correlated the sliding angle to the slippery surface of CF4-MP-PVDF and its anti-scaling property. This work proposed a well-defined physical and theoretical platform for investigating scaling problems in membrane distillation and beyond.
... In the qualitative assessment studies, the impacts generated from atmospheric emissions, discharge of heated effluents and chemicals into the marine environment, impacts of noise, effects on land use, and impacts on aquifers were discussed and explained without considering life cycle assessment (LCA). Hopner T. et al. [47] [11][12][13][14][15][16][17][18]. ...
Comprehensive environmental impact of thermal desalination is poorly understood in Middle Eastern and North African region, especially for multistage flash (MSF) desalination. Nearly 75% of Qatar's municipal water supply is being produced by MSF due to process reliability and other advantages, which is highly energy-intensive and creates an enormous environmental burden. Hence, this paper aimed to develop a multi-faceted, life-cycle based framework that quantifies the overall environmental and human health impacts of MSF desalination in Qatar. Three different MSF systems were examined by varying the gain ratio (GOR) through life cycle assessment. Different environmental loads were examined and evaluated, including climate change, freshwater eutrophication, fossil fuel depletion, ozone depletion, and human toxicity. The results showed that the modified MSF configuration with higher GOR released 7.32 kg CO2 for 1 m³ of water production while the plant with lowest GOR released 12.6 kg. Quantitative analysis of the environmental degradation caused by desalination reflects the reality of water use in Qatar and can motivate users to reduce their water consumption as part of the Qatar's national vision 2030. The implication of this study is particularly important at a regional level as it serves as a preliminary baseline for a more efficient water strategy.
... Chemicals dissolved in seawater contribute similar ions to those already present. For example, sulphuric acid increases the concentration of the SO 4 ions to 3020-3050 mg/l [2,[24][25][26][27]. Cleaning of membranes is conducted 3-4 times a year. ...
Desalination is an important means to meet water needs in many countries. The existing process is costly and energy intensive and further strains the environment with brine disposal and greenhouse gas (GHG) emissions. This paper describes several factors that are to be considered in desalination plants, such as the use of the land, the contamination of groundwater and the marine environment, the use of energy, and noise pollution. One major indirect environmental impact is the production of the energy required to run the desalination plants, particularly from burning oil, which increases GHG emissions. The carbon footprints associated with sea water desalination plants in the United Arab Emirates are assessed along with the other factors affecting human and marine life. There is no standard environmental impact assessment method, but the World Health Organization has begun work to produce one.
... The desalination process has relatively low environmental impact. However, it is reported that the discharge of brine into the sea may erode the seashore [25] or harm the aquatic life [26]. Moreover, to avoid unregulated development of coastal areas, desalination activity should be included in the regional development projects [27]. ...
... Seagrasses constitute one of the most productive marine ecosystems and cover large areas in the Aegean Sea. There is a worldwide loss of these valuable ecosystems resulting from direct human impacts, including mechanical damage, eutrophication, aquaculture, siltation, effects of coastal construction, food web alterations; and indirect human impacts including adverse effects of climate change (Duarte 2002;Latorre 2005). ...
This study was carried out to evaluate the phenological changes resulting from external impacts on Posidonia oceanica meadows along the Aegean coast. Triplicate samples were collected from 17 stations at 8 and 10 m depths by SCUBA diving between April and June 1999. The water temperature was measured and sediment type was determined in the stations. The phenological parameters; shoot density, leaf number, leaf area index, leaf surface area, brown tissue surface area and total biomass were investigated. One of the most important descriptors of Posidonia, shoot density, showed supranormal values at the seven of the meadows while only two of them showed abnormal values. Beside the natural factors such as water temperature and sediment types, the possible environmental or antrophogenic impacts on phenological characters of Posidonia meadows were discussed.
... However, this type of management is the least preferred due to its environmental consequence to marine environment and underground water. Disposed reject brine with high salinity could affect marine species such as P. oceanica [103]. Temperature of disposed reject brine can also play a major role by decreasing the dissolved oxygen in water and creating a hypoxic condition. ...
... Beside pre-dilution of the incoming water by SGP, the produced DES brine can also be used for additional energy production, as shown in Fig. 9 mixing the brine with a low-salinity water stream, the brine concentration will decrease, resulting in a lower environmental impact of the brine discharge into the sea (Bamaga et al., 2011;Lattemann and H€ opner, 2008;Latorre, 2005). In particular, mixing the brine with a very low-salinity water (e.g. ...
Renewable energy can be captured when mixing two water volumes with different salt concentration in reverse electrodialysis (RED), using ion exchange membranes (IEMs). This chapter describes the historical development of RED, membrane transport phenomena, practical RED operation, benchmark parameters and R&D perspectives. Amongst others, the effects of feed water composition, membrane and stack design and flow direction on the obtainable power density and efficiency are discussed for practical RED devices. This chapter reviews current research and indicates the remaining challenges and R&D perspectives for producing electricity from salinity gradients with RED.
... Beside pre-dilution of the incoming water by SGP, the produced DES brine can also be used for additional energy production, as shown in Fig. 9.3. Moreover, when mixing the brine with a low-salinity water stream, the brine concentration will decrease, resulting in a lower environmental impact of the brine discharge into the sea (Bamaga et al., 2011;Lattemann and H€ opner, 2008;Latorre, 2005). In particular, mixing the brine with a very low-salinity water (e.g. ...
The use of alternative water resources will become ever more important in the future, increasing the need for water desalination. Conventional desalination technologies, that is, multistage flash distillation, multieffect distillation, electrodialysis, and reverse osmosis, are well established but require high energy consumption. The coupling of these processes with salinity gradient power (SGP) offers the double benefit of decreasing the energy demand by the production of salinity gradient energy and by decreasing the salt concentration of the feed prior to desalination. Opportunities and challenges to combine SGP and desalination will be discussed in this chapter.
... Beside pre-dilution of the incoming water by SGP, the produced DES brine can also be used for additional energy production, as shown in Fig. 9.3. Moreover, when mixing the brine with a low-salinity water stream, the brine concentration will decrease, resulting in a lower environmental impact of the brine discharge into the sea (Bamaga et al., 2011;Lattemann and H€ opner, 2008;Latorre, 2005). In particular, mixing the brine with a very low-salinity water (e.g. ...
... Approximately 40-50% of the seawater treated by reverse osmosis (SWRO) is converted in to fresh water [1,2]. SWRO has three major draw backs: (i) high volumes of concentrate due to low water recovery, (ii) significant amounts of pre-treatment sludge that needs treatment and disposal and (iii) high energy consumption due to the use of high pressures to overcome the osmotic pressure of concentrated seawater [3][4][5][6][7]. Although the last draw back has been addressed well by the introduction of energy recovery devices [8,9], the first two draw backs still need solutions. ...
Seawater Reverse Osmosis (SWRO) desalination is being used by several countries to aid the current demand for fresh water, hence numerous large scale and small scale desalination plants have been built during last decade. Despite major advancements in SWRO technology, the desalination industry is still facing significant practical issues. Two of the major issues are (1) generation of higher volumes of pre-treatment sludge, and (2) overall water recovery. This paper proposes a novel hybrid reverse osmosis (RO) – forward osmosis (FO) system to overcome the above two drawbacks. Mass balance calculations based on laboratory experiments have been used to predict increased water recovery and reduced pre-treatment sludge volume arising from large scale (340,000 m3/day of intake) and small scale (15,000 m3/day of intake) hybrid SWRO desalination plants. The percentage reduction of pre-treatment sludge volume, increase in overall RO water recovery, FO membrane area required and dilution in RO reject have been estimated.
... In laboratory studies, a 36-39 ups discharge conditions were simulated, a 100% mortality in the adult was observed at 50 ups plants after 15 days, a 50% mortality of adult plants 45 ups, also observed that increasing the salinity decreases the rate of growth, at 40 ups the growth rate is reduced to 50% of control. In the field studies were not decisive enough to evaluate the effect due to the lack of physicochemical analysis in long-term study of the brine discharge [29]. ...
Background: Mining operations generate high demand of water resources in the areas where they operate; in Chile, the majority of major mining operations are concentrated in the north, close to the Atacama Desert, the driest desert in the world. Fresh water is no longer available in big quantities in the region; for this reason, new alternatives have been developed. The use of seawater and desalination plants has increased in the past years and significant projects are underway. Unfortunately, desalination plant discharge may have an environmental impact that needs to be studied and monitored. In this chapter, we attempt to review state of the art desalination technologies, their environmental impact, and the current situation in Chile, together with our recommendations to control and diminish any negative impacts desalination plants could potentially produce. Conclusion: In order to protect and preserve the marine environment and make use of seawater as a source of industrial water, it is important to study, measure, and evaluate the potential impacts of the desalination plant on the marine environment, implemented by multidisciplinary teams, in order to mitigate ecological harm. The benefits and economic impacts of a new source of water must also be evaluated taking into account the projected water needs of industrial operations in the region. Under these conditions, desalination plants have the potential to be a viable and sustainable technology.
... Moreover, discharged brine is one of the major environmental problems associated with the extensive practice of desalination technologies, considering that water recovery in SWRO operations generally ranges within 30-50%. Literature studies demonstrate adverse ecological and toxicological impacts of hypersaline brines on soil and groundwater [3], echinoids and ascidians [4], sediment infauna [5,6], seagrass and epifauna [7][8][9], planktons [10,11], fish and clam [12] etc. In addition, the net CO 2 emission associated with the generation of thermoelectric energy necessary to drive SWRO plants is about 1.4-1.8 ...
With a total capacity of 70 million cubic meters per day, seawater desalination industry represents the most affordable source of drinking water for many people living in arid areas of the world. Seawater Reverse Osmosis (SWRO) technology, driven by the impressive development in membrane materials, modules and process design, currently shows an overall energy consumption of 3-4kWh per m3 of desalted water, substantially lower than thermal systems; however, the theoretical energy demand to produce 1m3 of potable water from 2m3 of seawater (50% recovery factor) is 1.1kWh. In order to move towards this goal, the possibility to recover the energy content of discharged concentrates assumes a strategic relevance. In this work, an innovative approach combining Direct Contact Membrane Distillation (DCMD) and Reverse Electrodialysis (RE) is tested for simultaneous water and energy production from SWRO brine, thus implementing the concept of low energy and Near-Zero Liquid Discharge in seawater desalination. DCMD operated on 1M NaCl RO retentate fed at 40-50°C resulted in a Volume Reduction Factor (VRF) up to 83.6% with transmembrane flux in the range of 1.2-2.4kg/m2h. The performance of RE stack fed with DCMD brine (4-5.4M) and seawater (0.5M) was investigated at different temperatures (10-45°C) and flow velocities (0.7-1.1cm/s). Experimental data show the possibility to obtain an Open Circuit Voltage (OCV) in the range of 1.5-2.3V and a gross power density of 0.9-2.4W/mMP2 (membrane pair). In general, optimization is required to find best operating conditions for the proposed system.
... This volume of wastewater poses a significant management problem, and critical problems to the discharge environments: the sea (for seashore desalination plants) and underground aquifers (for inland desalination plants). The United Nations Environment Programme (UNEP-MAP) has recognized the problem of brine disposal as one of the major threats to the Mediterranean Sea. 2 More specifically, one of the most significant seagrasses of the Mediterranean Sea (Posidonia Oceanica), which is protected under the Barcelona Convention, has been identified to be highly vulnerable to salinity changes and as a result to brine exposure [20][21][22]. ...
Desalination is a water technology that is gaining increasing importance for addressing water needs, but it is costly and energy intensive and further strains the environment with brine disposal and greenhouse gas (GHG) emissions. In order to desalt seawater, either through membrane or thermal processes, a large amount of energy is required. Desalination has negative impacts in the form of depletion of fossil fuels and GHG emissions from the power production process to deliver this energy. What is more, the wastewater (brine) produced during the desalination process causes damages to the local sea environment where the brine is discharged. In order for desalination to be considered a sustainable water solution, both issues must be successfully resolved. This paper discusses the potential for coupling desalination with renewable energy (RES-D). Different renewable technologies can be combined with certain desalination techniques. The technical development stage of the RES-D combinations already applied is given. Currently applied management as well as an innovative alternative for brine management based on zero liquid discharge (ZLD) is also presented. This pilot system was developed in the framework of an European project with the acronym SOL-BRINE (LIFE09 ENV/GR/000299).
... In order to define the impacts of hypersaline water, several experiments have already been undertaken both in laboratory and in field, providing evidence that increased salinity severely affects growth rate, induces necrotic lesions and enhances meadow mortality (e.g. Fernández-Torquemada and Sánchez-Lizaso, 2005;Latorre, 2005;Gacia et al., 2007;Ruìz et al., 2009). Significant changes have been observed in plant traits such as a reduction in carbohydrates content (Gacia et al., 2007;Sánchez-Lizaso et al., 2008;Ruìz et al., 2009). ...
Posidonia oceanica meadows are sensitive to disturbance often associated with highly human-impacted coasts. A recent anthropogenic impact is due to hypersaline water produced by desalination plants of seawater that severely affects growth rate, induces necrotic lesions and enhances meadow mortality. To define the early effects directly correlated to salt regime variation on leaf tissue, we focused on aquaporins, water channel proteins of intracellular and plasma membranes. PIP aquaporins localization was carried out in leaf cross sections, using an antibody raised against the evolutionarily conserved N-terminal amino acid sequence of Arabidopsis thaliana PIP1;1 (which showed 84% of identity with P. oceanica PIP1;1 aquaporin), both in leaves kept in natural seawater and in leaves subjected to hypersaline treatment. In natural seawater conditions, the antibody was localized mainly in epidermis and weakly in vascular bundles and mesophyll tissues of leaves. A widespread increase of fluorescence was observed in leaves subjected to hypersaline regime. Hence, our results showed histological evidence of PIP1;1 peptide increase following salt stress. Our data also suggest that aquaporins are involved in osmotic balance maintenance in seagrasses.
... The desalination process has relatively low environmental impact. However, it is reported that the discharge of brine into the sea may erode the seashore [25] or harm the aquatic life [26]. Moreover, to avoid unregulated development of coastal areas, desalination activity should be included in the regional development projects [27]. ...
Beyond doubt, desalination is growing rapidly worldwide. However, there are still obstacles to its wider implementation and acceptance such as: (a) high costs and energy use for fresh water production; (b) environmental impacts from concentrate disposal; (c) a complex, convoluted and time-consuming project permitting process; and (d) limited public understanding of the role, importance, benefits and environmental challenges of desalination. In this paper, a short review of desalination in Greece is being made. Data on the cost of desalination shows a decrease in the future and the potential of water desalination in Greece. The paper summarizes the current status in southeastern Greece (e. g., Aegean islands and Crete), and investigates the possibility of production of desalinated water from brackish water.
... En la costa Mediterránea de España hay cinco clases de praderas marinas de angiospermas la más abundante es Posidonia oceanica fanerógama, endémica del mar Mediterráneo. En los últimos años, se han llevado a cabo estudios de la tolerancia a la salinidad de la Posidonia oceanica, llegando a fijar la salinidad máxima tolerable en 38,5 psu (unidades practicas de salinidad) que son aproximadamente equivalentes a 39 g/l [5]. Un estudio al oeste del Mediterráneo [6], encuentra ratios más bajos de crecimiento y más alta mortalidad de Posidonia oceanica con niveles de salinidad por encima de 39,1 psu. ...
Los efectos medioambientales son uno de los principales problemas de las instalaciones de desalación de agua de modo masivo. Para alcanzar el objetivo ideal de evitar la descarga de salmuera de rechazo en la desalación de agua de mar, la sal debe ser completamente separada del agua, obteniéndola como un producto secundario de valor económico. Si además no se desea aumentar las emisiones de CO2, la energía necesaria debe extraerse de una combinación de fuentes renovables. Este trabajo presenta un análisis de un esquema integrado de desalación consistente en dos subsistemas secuenciales: una planta de destilación multiefecto (MED) y un ciclo evaporativo por compresión mecánica de vapor (CMV). La energía se obtiene de varias turbinas eólicas y de un campo de colectores solares.
El sistema diseñado produce 100 m3/h de agua dulce con total separación de la sal y el agua. El consumo energético estimado es de 2.362 Kwt-h por el sistema MED y 1.944 Kwe-h por el CMV. Al utilizar energías renovables la reducción de emisiones de CO2 a la atmósfera al año es de 8.957 Tn debidas al consumo eléctrico y 6.584 Tn al consumo térmico. Se ha realizado un estudio preliminar de la inversión, la amortización y los costes de explotación del sistema completo. Teniendo en cuenta los precios de la venta de la energía producida y de la sal, el precio del agua sería de 0,59 €/m3. Con una subvención inicial del 35%, se podría reducir a 0,41 €/m3.
... However, in most cases, the water recovery is less than 55% [1], and a large amount of brine with a higher salinity of 65,000-85,000 mg/L is generated from RO process [2]. These concentrated brines are often disposed to the lakes, rivers or oceans, which would be harmful to the surface, ground water and ecosystem [2,3]. Further treatment of concentrated brines is desired to reduce the negative impact of concentrated brines on the environment and enhance water recovery, as well as recovery of valuable inorganic elements [1,4,5]. ...
Highly concentrated NaCl, KCl, MgCl2 and MgSO4 solutions were treated using DCMD. The effects of salt concentration (1.0 –4.0 mol/L) and circulation velocity (0.1–0.5 m/s), as well as thermodynamic and physical properties of the salt solutions on permeate flux were investigated. Results showed that the permeate fluxes decrease with increasing concentration for the four salts solutions studied, which follows the order of KCl > NaCl > MgSO4 > MgCl2 at the salt concentrations higher than 1.0 mol/L. The different vapor pressure depression caused by reduction of water activity was identified as the main reason behind this. However, the drastic increase of viscosity of MgSO4 and MgCl2 solutions at higher salt concentrations would also have a notable adverse impact on permeate flux. Under these circumstances, change of hydrodynamics, i.e. increase of circulation velocity would be a great help to improve the heat transfer and then the flux. To prevent salt from crystallizing on membrane surface in saturated conditions, the feed inlet temperature should be controlled within a certain range, and it was 40 to 50 °C, 40 to 45 °C and 25 to 35 °C for NaCl, KCl, and MgSO4, respectively in this study.
... Brine disposal on land has a significant adverse effect on aquifer (Mohamed et al. 2005). On the other hand by discharging back to the sea there can be impacts on marine fauna and flora (Latorre 2005) and algae formation near the beach (Ahmed et al. 2001). Many of the disinfection byproducts (DBPs) formed during pre-treatment and post treatment (a result from reactions between organic and inorganic matter in water with chemical disinfection agents such as bromide, ozone, Cl 2 etc.) will be discharged with the brine and they could affect marine ecosystems if they are not diluted sufficiently after discharge (Agus et al. 2009). ...
Seawater desalination has significantly developed towards membrane technology than phase change process during last decade. Seawater reverse osmosis (SWRO) in general is the most familiar process due to higher water recovery and lower energy consumption compared to other available desalination processes. Despite major advancements in SWRO technology, desalination industry is still facing significant amount of practical issues. Therefore, the potentials and problems faced by current SWRO industries and essential study areas are discussed in this review for the benefit of desalination industry. It is important to consider all the following five components in SWRO process i.e. (1) intake (2) pre-treatment (3) high pressure pumping (4) membrane separation (performance of membranes and brine disposal) and (5) product quality. Development of higher corrosion resistant piping materials or coating materials, valves, and pumps is believed to be in higher research demand. Furthermore, brine management, that includes brine disposal and resource recovery need further attention. Pre-treatment sludge management and reduced cleaning in place flush volume will reduce the capital costs associated with evaporation ponds and the maintenance costs associated with disposal and transportation reducing the unit cost of water.
Experimental design:
For the analysis of macroinvertebrates associated with the Posidonia oceanica meadow, the factor was depth. Three levels were established: an external zone (38.914oN, 1220oE), at a depth of 15.5 m, another in the intermediate zone, at 12.5 m (38.915oN, 1222oE) and a last one near the coast, at 4 m ( 38.913oN, 1.222oE) (Figure 1). The variable to be measured was the abundance of individuals per m2.
A non-destructive method was used, based on visual censuses and with autonomous diving equipment. In each study area, 3 random transects of 10 meters long by 1 meter wide were made. In total, 9 random transects were carried out in Cala Vedella. Similarly, for the study of the epiphytes, 5 bundles of Posidonia oceanica were taken per zone. Their study was carried out by counting the animal and vegetable cover of the outer distal and proximal parts of the outer leaves of each bundle, following the method used by Eugene (1978).
Statistic analysis:
Once the data was obtained, an analysis was performed with PERMANOVA to see the existence of differences in the composition of macroinvertebrates between the 3 zones. In addition, a dendrogram and an nMDS were performed in order to observe the dispersion between zones. In both cases, the Bray Curtis distance was used (Clarke and Warwick, 2001). For the epiphytes, an ANOVA was used with the R Project software (R Core Team, 2017) to observe the differences in the total cover, of vegetables and of epiphytes depending on the season and the position on the leaf with the following model linear:
Xijk=μ+Zonai+Hojaj+Zona*Hojaij+Ɛk(ij)
For the total cover, the data were transformed for the homogeneity of variances and an alpha of 0.05 was used, while for the animal and vegetal cover, when homoscedasticity was not met, an alpha of 0.01 was used. To see the differences between the different factors, the Tukey test was used.
In order to obtain a better characterization of the macroinvertebrate populations, different diversity indices were used, such as the Shannon-Weaver index (Shannon and Weaver, 1949) and the Pielou evenness (Pielou, 1966) with the PAST program (Hammer et al. al., 2001).
Experimental design:
For the analysis of macroinvertebrates associated with the Posidonia oceanica meadow, the factor was depth. Three levels were established: an external zone (38.914oN, 1220oE), at a depth of 15.5 m, another in the intermediate zone, at 12.5 m (38.915oN, 1222oE) and a last one near the coast, at 4 m ( 38.913oN, 1.222oE) (Figure 1). The variable to be measured was the abundance of individuals per m2.
A non-destructive method was used, based on visual censuses and with autonomous diving equipment. In each study area, 3 random transects of 10 meters long by 1 meter wide were made. In total, 9 random transects were carried out in Cala Vedella. Similarly, for the study of the epiphytes, 5 bundles of Posidonia oceanica were taken per zone. Their study was carried out by counting the animal and vegetable cover of the outer distal and proximal parts of the outer leaves of each bundle, following the method used by Eugene (1978).
Statistic analysis:
Once the data was obtained, an analysis was performed with PERMANOVA to see the existence of differences in the composition of macroinvertebrates between the 3 zones. In addition, a dendrogram and an nMDS were performed in order to observe the dispersion between zones. In both cases, the Bray Curtis distance was used (Clarke and Warwick, 2001). For the epiphytes, an ANOVA was used with the R Project software (R Core Team, 2017) to observe the differences in the total cover, of vegetables and of epiphytes depending on the season and the position on the leaf with the following model linear:
Xijk=μ+Zonai+Hojaj+Zona*Hojaij+Ɛk(ij)
For the total cover, the data were transformed for the homogeneity of variances and an alpha of 0.05 was used, while for the animal and vegetal cover, when homoscedasticity was not met, an alpha of 0.01 was used. To see the differences between the different factors, the Tukey test was used.
In order to obtain a better characterization of the macroinvertebrate populations, different diversity indices were used, such as the Shannon-Weaver index (Shannon and Weaver, 1949) and the Pielou evenness (Pielou, 1966) with the PAST program (Hammer et al. al., 2001).
Salinity gradient energy (SGE) exists in solutions with different salinity, such as seawater and freshwater. However, recovery of this energy between concentrated seawater discharged from desalination plants and seawater is rarely studied. Here, the reverse electrodialysis (RED) approach is proposed to capture this energy for power production. The main works are: i) Investigating influence law of feed parameters on the performances of a RED stack. ii) Exploring the influences of the sediments in concentrated seawater, produced in thermal desalination process, on performances of the stack. When seawater is used as dilute solution, open-circuit voltage of the RED stack increases 2.39 times from 0.132 V to 0.448 V with concentration of concentrated seawater increasing from 1.0 mol L⁻¹ to 3.0 mol L⁻¹, and the maximum power density increases from 0.0120 W m⁻² to 0.184 W m⁻². Increasing the temperature and velocity of feed solution can improve the performance of the RED stack, but with the limitation of concentration difference. The sediments in concentrated seawater are harmful to output performances of the RED stack. After filtrating most sediments, the maximum power density increases 19%, and open-circuit voltage increases 9.4%, compare to their original values.
Brine released from desalination plants is extremely high in salinity and contains various chemicals, which are harmful to the ecosystem. The disposal of brine has raised great concerns for the desalination industry around the world due to its detrimental impact on fauna and flora. This review complies with various zero liquid discharge technologies that have been proposed for successful brine disposal which aims to minimize the impact of brine discharge. Moreover, it highlights some of the detrimental impacts of brine discharge on marine fauna and Flora. It also discusses both thermal and membrane technologies for recovering freshwater, energy, and minerals from waste brine, in addition to the recent advances in a solar pond, membrane distillation, pressure retarded osmosis, etc. In Driver-Pressure-State-Impact-Response (DPSIR) framework was used in this review to analyze the water resource system in Qatar. This review also facilitates and provides a comprehensive approach in minimizing the potential impact of brine discharge which can be practiced and applied in countries where desalination plants are set up. This promotes cleaner production, sustainability, and recycling of waste that will help protect and preserve the country's natural water resources.
Desalination technologies play a vital role in water production. Along with the production of clean drinking water, desalination plants produce waste in the form of hypersaline water or brine which may harm the surrounding environment. This paper proposes a method of brine management using microalgae. The alga species Nannochloropsis sp. was tested for its ability to grow in high salt stress conditions, up to 80 g L–1, and in desalination brine with concentration of 70 g L–1. Interestingly, four- and five-fold increases in biomass were observed in salt stress conditions of 60, 70, and 80 g L–1. In the case of the desalination brine conditions, Nannochloropsis sp. growth resulted in comparable biomass values to the salt stress experiments, proving that algal growth was not inhibited due to the presence of brine. For cost efficiency, further research was conducted to optimize the concentra-tion and components of the brine-nutrient medium. The best growth was obtained in the optimized brine-based F/2 medium (BUV), which was scaled up and tested for its bio-desalination and bio-fuel capacities. Biomass productivity and lipid productivity were found to be 0.05 ± 0.016 g L–1 d–1 and 9.5% ± 2.1% w/w, respectively. This study presents a cost-effective sustainable method for brine management through which value is created.
Due to extremely high rates of evaporation and low precipitation in the Persian Gulf, discharges from desalination plants (DPs) can lead to ecological stresses by increasing water temperatures, salinities, and heavy metal concentrations, as well as decreasing dissolved oxygen levels. We discuss the potential ecological impacts of DPs on marine organisms and propose mitigating measures to reduce the problems induced by DPs discharges. The daily capacity of DPs in the Persian Gulf exceeds 11 million m3 d‐1, which is approximately half of global daily fresh‐water production; multi‐stage flash distillation (MSF) is the dominant desalinization process. Results from field and laboratory studies indicate that there are potentially serious and chronic threats to marine communities following exposure to DPs discharges, especially within the zoobenthos, echinodermata, seagrasses, and coral reefs. DP discharges can lead to decreases in sensitive species, plankton abundance, hard substrate epifauna, and growth rates of seagrasses. However, the broad applicability of any one of these impacts is currently hard to scale because of the limited number of studies that have been conducted to assess the ecological impacts of DP discharge on Persian Gulf organisms. Even so, available data suggest that appropriately sited, designed, and operated DPs combined with current developments in impingement and entrainment reduction technology can mitigate many of negative environmental impacts of DPs.
Desalination is considered one of the most viable and technically feasible strategies for the production of freshwater from saline solutions (brackish water, seawater and brine). Thousands of membrane and thermal desalination plants operate daily in many countries around the world, with thermal desalination plants being more advantageous especially in areas with cheap energy. Stainless steel is a reliable material choice for thermal desalination plants due to excellent properties such as stability and minimum maintenance requirements. However, corrosion can cause catastrophic failures in stainless steel due to high temperatures and corrosive environments. The purpose of this review is to provide an overview of stainless steel grades (austenitic, super austenitic, duplex, super duplex and hyper duplex) that have been and can be used in thermal desalination and brine treatment applications and discuss their opportunities and challenges. In terms of mechanical properties and corrosion resistance, the grades of stainless steel are compared. Thus, for each grade, an application area is suggested to minimize the possibility of material failure. Furthermore, this review discusses recent trends in stainless steel corrosion control and anti-corrosion materials and methods.
This study is a bibliometric research about anthropic impacts on Posidonia oceanica meadows from all Mediterranean sea. The aim is synthesizing the status of the issue and analyzing quantitatively the distribution of scientific articles concerning the ecoregion, the type of impact which is studied and their chronological tendency. The investigation was carried out through bibliographic researches in some databases and the literature found was classified and quantified. Lately, the quantitative information was tested with ANOVA and linear regression analysis in order to find out which type of impact and ecoregions were the most widely studied, the origin of these tendencies and if they had a relationship with the intensity of impact, the conservation status in each area or the resources the scientist community has. The results show that literature tends to increase over time. This literature focuses on Algero-provençal basin and concerns mainly aquaculture and coastal development. Other complementary results were a list of reference including authors and scientific journals and also a compilation of the bibliography used for statistical analysis, which was classified according to the type of impact.
The usefulness of this study lies in its ability to facilitate the bibliographic research for future investigations, summarizing key concepts and giving the reader a global vision on one hand about the condition of the basins and the pressures they suffer because of human beings, on the other hand facilitating interesting literature.
The situation of water sector in the Gaza Strip-is characterized by many parties as humanitarian crisis- where the underling groundwater, the only water resource, is used extensively to supply water for domestic, agricultural and industrial sectors. The major part of the groundwater is grossly exploited and contaminated with high levels of pollutants, e.g. chloride (Cl) concentrations range between 600–2000 mg/l and nitrate (NO3) concentrations range between 50 and 200 mg/l, these levels exceed World Health Organization (WHO) and Palestinian Water Authority (PWA) guidelines for drinking water. In response to this water crisis, the PWA put a comprehensive plan to construct three short-term low-volume (STLV) seawater desalination plants to provide Gaza Strip by a total of 13 million cubic meters per year of freshwater. The regional short-term low-volume (SLTV) seawater desalination plant is considered as an urgent solution to mitigate the suffering from water crisis in the southern region of the Gaza Strip. Currently, the plant provides the water sector by 2.2 million cubic meters of freshwater per year. The plant will be upgraded to provide about 7.3 million cubic meters of freshwater per year for domestic uses. However, as a product from the reverse osmosis process, huge amount of brine, nearly 8.92 million cubic meters per year, with salinity reaches to 75,000 mg/L will be redirected to seawater. This paper employs the powerful of numerical modelling to suggest proper mitigation measures in order to minimize the negative environmental impacts of brine disposal on the marine ecosystems. This study uses the model of CORMIX v 9.0 to simulate the dispersion and dilution behavior of discharged brine through eight disposal systems classified under four classes of configurations: single port outfall, alternating multi port diffuser, unidirectional multi port diffuser and staged multi port diffuser. The sensitivity of change in the ambient conditions over the four seasons of the year plays a significant role in enhancing or inhibiting the process of brine mixing, dilution and dispersion. Taking salinity variations as an indicator, the simulation results of discharged brine via various outfalls configurations into the marine environment over the four annual seasons show that the fanned-out unidirectional multi port outfall of option (7) is the optimal design configuration, where discharging the produced brine from the regional STLV plant via option (7) can meet the disposal standard at RMZ in the worst ambient condition of autumn at low astronomical tide (LAT) by reducing the brine’s excess salinity at the edge of mixing zone to less than 1.25% (488 mg/L) above seawater salinity.
Negatively buoyant jets develop when fluids are released upwards into a lighter fluid or, vice versa, downwards into a heavier fluid. There are many engineering applications, such as the discharge, via submerged outfalls, of brine from desalination plants into the sea. Some concerns are raised about the potential negative environmental impacts of this discharge. The increase in salinity is the major cause for environmental impact, as it is very harmful to many marine species. The diffusers for brine discharge are typically inclined upwards, to increase the path before the brine reaches the sea bottom, as it tends to fall downwards driven by negative buoyancy. The negatively buoyant jet that develops conserves axisymmetry only when released vertically, so that it is not possible to use the well-known equations for axisymmetric jets. The main target of this paper is to investigate on a laboratory model the effects of different stratifications on the features of negatively buoyant jets. This has been done via a LIF (Light Induced Fluorescence) technique, testing various release angles on the horizontal and densimetric Froude numbers. Except for the initial stage, a different widening rate for the upper boundary and the lower boundary has been highlighted.
The technical feasibility of using venturi diffusers rather than conventional devices to enhance dilution processes was studied at the Maspalomas II desalination plant (Canary Islands, Spain). The venturi eductors needed very high exit velocities (≥ 11 m/s) to reach the pressure difference required to produce the suction effect of these devices. At these velocities, the venturi eductors were more efficient than cn conventional diffusers, as they achieved O much higher dilutions, by around 35% beyond the mixing zone. Venturi eductors definitely discharge with lower exit velocity than conventional diffusers and q within the range of velocities normally used. Dilutions as high as these are not only very useful, but also necessary, as part of the island's largest and most ecologically important seagrass meadow of Cymodocea nodosa is found nearby.
Understanding the role of a global seawater desalination plant project using potential ecological indicators is important in assessing ecological risk and/or impact evaluations from observations at a molecular level. A marine health assessment of ecological indicators (e.g., as an early-warning system) can provide information about an area of ecosystem disturbance, the disappearance of symbiosis, organism mortality, instability of fertility and breeding species, the emergence of single species, the bioaccumulation of test bed operation pollutants discharged, and changes in the communities. Here, we provide a comprehensive review of ecosystem health assessments using potential ecological indicators in a seawater desalination test bed. We review some empirical analyses and compare desalination concentrate treatments, the impact of reverse osmosis and multistage flash, chemicals used in the plant, the impact pathway, the brine outfall pipe, an operational assessment, salinity tolerances, and the eco-toxicological effect of brine in a marine ecosystem. Based on literature research results and data illustrating the degraded ecosystem and/or the original ecosystem, stress caused by a desalination project on the marine ecosystem damage can provide information about the marine ecosystem disturbance, the disappearance of symbiosis relationship, which may be as important as sustainable management using living ecological indicators.
This paper briefly introduced the composition and properties of brine from seawater desalination plant and mainly reviewed the effect of discharged brine on the marine ecological environment. Then we analyzed the effect of salinity and temperature of brine on plankton, benthos, fish and seagrass. A quantity of discharged brine will cause marine water quality deterioration, make the economic marine species decrease, resulting in the loss of fishery resources and marine economy. Therefore, it is necessary to strengthen the study and monitoring of marine ecological environment, for maximize reducing the negative influence of discharged brine on the marine environment.
In this study, the combination of cooling towers and plate heat exchanger was used to concentrate the seawater after desalination. The experimental results show that: The heat transfer coefficient was found to increase by 9.6% as the concentration of desalinated seawater with softening pretreatment was increased four times. With the concentration of the brine increases three times, the outlet temperature of cooling tower decrease by 1.1 degrees C, the heat emission efficiency of cooling tower increases by 13.4%, and the evaporation loss of cooling tower increases by 20% per hour.
A panel of five experts in diverse fields related to brine disposal in the ocean was convened to advise the State Water Resources Control Board on best practices for brine disposal in support of the development of an amendment to the Ocean Plan. The brine concentrates can result from desalination of brackish groundwater, recycling domestic wastewater, and especially desalination of seawater. The potential of seawater desalination to provide potable water in the state is growing rapidly, with many plants currently proposed or in the planning stage. The state presently has no regulations on brine discharges and each plant is considered on a case-by-case basis.
The panel reviewed extensive material, including peer-reviewed journal articles, articles in the gray literature, NPDES permits that have been issued, various regulations from around the world, and results of monitoring studies, and heard presentations about experience with operating discharges.
From these reviews it is apparent that concentrate can be disposed of with minimal environmental effects if properly executed. Desirable methods of discharge include co-disposal with heated cooling water from power plants or domestic wastewater, or from a multiport diffuser if “pure” brine is released. Discharges with rapid initial dilution into areas of good flushing result in impacts that extend only a few tens of meters from the discharge. Conversely, poorly implemented disposal schemes with low initial dilution in poorly flushed areas can cause widespread alterations of community structure in seagrass, coral reef, and soft-sediment systems.
Extensive literature on the toxic effects of concentrates were reviewed. The effects (or lack thereof) of desalination concentrate vary widely, depending on the organism, site, the biotic community at the site, the nature of the concentrate, and to what degree it is dispersed. It appears that benthic infaunal communities and sea grasses are the most sensitive; some communities seem to be tolerant of effects of up to 10 psu increases, while others are affected by increases of only 2-3 psu. None of the studies reviewed indicated any impacts of elevated salinity levels less than 2-3 psu. It should be noted, however, that very few peer-reviewed studies have evaluated sublethal effects of desalination discharges either in the laboratory or in the field. It should also be noted that few studies have evaluated “worst-case” embayment scenarios and chronic impacts on demersal vertebrates, particularly those which have significant life history behaviors (i.e., reproduction, migration) driven by salinity variations. For example, embayments with limited flushing may have thresholds lower in anadromous fish such as salmonids or estuarine demersal flatfish, which undergo saltwater acclimation and significant endocrine alterations. Additional and long-term studies are needed on sublethal endpoints such as reproduction and on different types of concentrates and mixtures with antiscalants and other chemicals associated with RO.
We also reviewed regulations and standards that have been applied around the world. These range from salinity increments within 1 ppt, 5%, or absolute levels such as 40 ppt. These limits typically apply at the boundary of a mixing zone whose dimensions are of order 50 to 300 m around the discharge.
Because discharges can be designed to result in rapid initial dilution around the discharge, we recommend that they be regulated by a mixing zone approach wherein the water quality regulations are met at the mixing zone boundary. The mixing zone should encompass the near field processes, defined as those influenced hydrodynamically by the discharge itself. These processes typically occur within a few tens of meters from the discharge, therefore we conservatively recommend that the mixing zone extend 100 m from the discharge structure in all directions and over the whole water column.
Based on the studies of effects of brine discharges we recommend an incremental salinity limit at the mixing zone boundary of less no more than 5% of that occurring naturally in the waters around the discharge. Expressing the limit as a percentage increase allows for natural variability in the background waters. For most California open coastal waters this increment will be about 1.7 ppt; for a typical seawater desalination plant where the brine is concentrated by a factor of roughly two times, this corresponds to a dilution of about 20:1, which should be readily achievable. The dilution is the combination of in-pipe dilution in the case of co-discharges, and near field mixing. In addition to the salinity requirement, the discharge should meet toxicity and other requirements in the Ocean Plan at the edge of the mixing zone.
Co-discharges with power plant cooling water or domestic effluent can be positively buoyant, i.e. less dense than the receiving water. In that case, the regulatory framework of the Ocean Plan should be sufficient for protection of beneficial uses. Near field models should be re-run, however, to account for the increase in effluent density and flow rates on plume behavior.
The preferred methods of discharge are from a multiport diffuser for “raw” effluents, or co-disposal with power plant cooling water or domestic wastewater that results in significant in-pipe dilution. These discharges can be either a shoreline surface discharge (if positively buoyant) or through an existing multiport diffuser. Shoreline discharge of raw effluent is discouraged due to slow near field mixing and potentially high exposures of benthic organisms to elevated salinity.
In computing near field dilutions of negatively buoyant discharges from diffusers, conservative assumptions should be applied: that ocean currents do not increase dilution, and the seabed is flat and horizontal. To account for possible reductions in dilution in areas of poor flushing, estimates of overall flushing of the discharge site should be made to ensure that the dilution requirement at the edge of the mixing zone is still met.
No specific mathematical models are endorsed, but it is recommended that calculations be made using either tested semi-empirical equations available in the literature or by integral mathematical models based on entrainment assumptions. Mathematical models should be validated, and attention should be made to special conditions that occur with typical negatively buoyant discharges such as reduction in dilution due to Coanda effects and jet merging in the case of multiport diffusers.
Because of uncertainties in plume modeling and predicting the biological effects of the discharges, a field monitoring program should be used. Monitoring should include pre-discharge conditions and continue after discharge has begun to evaluate changes in the ecosystem. We recommend that the receiving water monitoring programs be based on Before-After Control-Impact (BACI) monitoring that includes multiple reference locations, samples at various distances from the discharge, and repeated sampling over time. The effluent should also be monitored for specified physical and chemical parameters.
The growth and population dynamics of Posidonia oceanica were examined in 29 meadows along 1000 km of the Spanish Mediterranean coast (from 36 degrees 46' to 42 degrees 22' N). P. oceanica developed the densest meadows (1141 shoots m(-2)) and the highest aboveground biomass (1400 g DW m(-2)) between 38 and 39 degrees N. P. oceanica shoots produced, on average, 1 leaf every 47 d, though leaf formation rates in the populations increased from north to south (range 5.7 to 8.9 leaves shoot(-1) yr(-1)). P. oceanica is a long-living seagrass, with shoots able to live for at least 30 yr. P. oceanica recruited shoots at low rates (0.02 to 0.5 In units yr(-1)) which did not balance the mortality rates (0.06 to 0.5 In units yr(-1)) found in most (57%) of the meadows. If the present disturbance and rate of decline are maintained, shoot density is predicted to decline by 50% over the coming 2 to 24 yr. Because P. oceanica rhizomes grow very slowly (1 to 6 cm yr(-1) apex(-1)), maintenance of existing meadows is essential, and our results suggest bad future prospects for P. oceanica in the Spanish Mediterranean Sea like most other seagrass species in the world oceans.
The present study compares fish assemblages from two Posidonia oceanica (L.) Delile, 1813, meadows off the coast of Murcia (western Mediterranean). These meadows presented different degrees of conservation, one of them disturbed by otter trawling. Different structural parameters of the fish assemblage (abundance in number and biomass, specific richness and diversity) were studied, comparing localities and seasons (spring, summer, autumn and winter). Qualitatively, the more relevant differences seemed related to a specific component, with the presence of species typical of littoral soft bottoms (sand, muddy-sand) observed in the degraded meadow. Quantitatively, although some differences were observed among meadows and seasons, these were not significant, except for species richness and the abundance (in terms of numbers and biomass) of some species. The analysis of these results takes into account the possible changes in cover and complexity of the meadow.
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