High Salinity Water Research Articles

Enhanced solar-driven steam generation and water purification using 3D arch solar evaporators

Steam generation strategy through solar-driven evaporators has now been widely recognized as one of the effective means to relieve the global fresh water crisis. Reducing heat loss has shown to be an effective way to improve the evaporation efficiency which has been overlooked in three-dimensional (3D) evaporators in the past. Herein, a superhydrophilic photothermal fabric was developed by the layer-by-layer assembly of carbon nanotubes followed by dip-coating with polyvinyl alcohol. The as-obtained photothermal fabric was designed as a 3D arch solar evaporator (ASE). The arch structure allowed the photothermal fabric to achieve double-sided water evaporation and a well-balanced saline water supply by controlling the height of the ASE. The ASE effectively captured the incident sunlight and demonstrated extraordinary thermal management performance, resulting in a saline water evaporation flux of 1.015–3.400 kg m−2 h−1 under 1 sun irradiation for 6 h. In addition, the proposed ASE exhibited excellent water purification for high salinity saline water, colored wastewater, and heavy metal wastewater. This work provides new insights into emerging solar steam generation systems by regulating the saline water supply balance.

Indicators of rapid adaptation of an exotic aquatic Poaceae to increased salinity

AbstractThe invasion process and the persistence of invasive species across environments can be explained by their tolerance to stressors, such as salinization. Urochloa arrecta (Poaceae) exhibits high invasive potential and has already established in various natural and artificial aquatic ecosystems. Here, we experimentally evaluate the effects of water salinity on the traits of three exotic populations of U. arrecta derived from naturally occurring populations across a salinity gradient. Specifically, we measured the difference in the number and perimeter of intercellular spaces for individuals from the different populations across three experimental treatments of salinity. Our results demonstrate that high water salinity levels affected anatomical traits in all populations. However, the traits of freshwater populations were the more significantly impacted by increasing salinity compared with populations sampled from naturally higher occurring salinity. Populations of U. arrecta established in places with certain degree of salinity can be more resistance to salt increases compared with populations established in freshwater habitats that are more distant geographically. However, the resistance of freshwater populations to certain high salinity levels suggests that these populations may exhibit rapid adaptation and to survive under some degree of salinity, demonstrating the species' high resilience across various environments.

Matching of Water Breakthroughs in a Low-Resistivity Oil Reservoir Using Permeability Anisotropy

In a mature middle and lower Gharif field in Oman, uncertainties surrounding initial water saturation and early water breakthroughs of unknown sources and paths suggest the presence of significant bypassed oil. In order to determine the areas with remaining oil, petrophysical and logging data of seven wells were processed using Techlog software and imported into Petrel software for modelling and simulation. Porosity was calculated using the Electric Propagation Time log and was utilized to evaluate the presence of oil, particularly in the upper tight zone of the formation. Despite the low resistivity readings in the highly porous layers, caused by good network connectivity and high formation water salinity, the resistivity contrast was sufficient to differentiate them from the oil zone. However, the calculated water saturation (Sw) in the tight top oil zone was high, consistent with the observed water production in the field. To improve the match between production data and simulation results, sensitivity analyses were conducted on various permeability anisotropy and relative permeability values within the model. The analyses showed that core-derived permeability anisotropy (vertical to horizontal ratio of 1:1) yielded a better history match for water production compared to the conventionally used value of 1:10. Water saturation maps were generated at the start and the end of production to highlight saturation distribution within the reservoirs. The maps revealed that in the lower porous part, the oil was fully depleted around the wells but remained trapped in the undrilled areas.

Unveiling the potential: Thin film composite membranes and joule heating synergy for pervaporation desalination

Pervaporation emerges as a promising technology for desalinating high-salinity water, yet its broader application is constrained by low productivity and significant energy requirements. This study introduces a unique thin-film composite membrane featuring a polyamide active layer atop a support membrane comprised of carbon nanostructures and networked cellulose. The carbon nanostructures, being electrically conductive, were crucial for enabling Joule heating, thereby significantly enhancing desalination efficiency. The membrane demonstrated a superior flux of 41.85 LMH and a rejection rate of around 99 % for a 3.5 g/L NaCl feed. Pervaporation desalination tests revealed that the Joule-heated membrane achieved higher fluxes than conventional heating methods. The enhanced flux is attributed to diminished temperature polarization and enhanced water and vapor diffusion facilitated by the membrane's elevated temperature. At a comparable permeate flux of around 17 LMH, Joule heating led to a 46 % reduction in specific heating energy consumption compared to conventional heating. This study provides valuable insights into developing efficient thin-film composite membranes with joule heating capabilities for pervaporation desalination, marking a significant step forward in addressing the challenges of high-salinity water treatment via pervaporation.

The effects of saline water consumption on sperm parameters, testicular histopathology, hormonal and antioxidants concentrations in Barki Rams

The study aimed to assess the effects of water salinity on the sperm parameters, levels of cortisol, LH, FSH, testosterone and antioxidants as well as the testes’ histopathology in Barki rams. Fifteen healthy Barki rams (1–1.5 years) were divided into three equal depending on the type of drinking water for nine months. The rams in the tap water group (TW, water that contained 350 ppm of total dissolved salts (TDS). Males in the high saline water group (HSW) were permitted to consume high saline water with 8,934 ppm TDS, whereas those in the second group were permitted to have moderately saline water (MSW, 4,557 ppm TDS). High salt concentration in drinking water had adverse effect on sperm viability, morphology and sperm cell concertation. Nitric oxide and malondialdehyde concentrations in blood were significantly higher in the MSW and HSW groups than in TW. There was a significant decrease in glutathione concentration as well as superoxide dismutase activity in TDS and HSW. Cortisol was most highly concentrated in the HSW, next in the MSW, and least in TW. The testosterone, LH, and FSH concentrations in the HSW and MSW groups were significantly lower than in TW. As the salt concentration in drinking water increases, damage to testicular tissue. The MSW group demonstrating vacuolation of lining epithelial cells with pyknotic nuclei in the epididymis and necrosis and desquamation of spermatogenic cells in seminiferous tubules while HSW group displaying desquamated necrotic cells and giant cell formation in the epididymis, as well as damage to some of the seminiferous tubules and showed congestion, vacuolation of spermatogenic epithelium of seminiferous tubules, and desquamated necrotic spermatogenic epithelium. In conclusion, the salinity of the water has detrimental impacts on the sperm morphology, viability and concentration, hormones and antioxidant levels in Barki rams.

Preparation and modification of PVDF membrane via VIPS method for membrane distillation

Membrane distillation (MD) is a promising technology for treating high-salinity mine water. However, MD membranes are known to have low membrane flux and are prone to fouling. In this study, we used the cost-effective and controllable vapor-induced phase separation (VIPS) technology to prepare polyvinylidene difluoride (PVDF) membranes, replacing the traditional immersion precipitation method and optimizing the membrane structure by including LiCl and acetone as porogen in the casting solution. The results showed that the membrane prepared using the VIPS method exhibited a highly open interconnected porous surface. Unlike traditional MD membranes with a dense epidermal layer and large finger-like pores, these optimized membranes had a symmetrical and uniform internal structure, leading to a high flux of 8.62 kg·(m2·h)−1 during direct contact membrane distillation testing. Different porogens produced varied results on the VIPS process and varying effects on membrane structure. The use of LiCl promoted the formation of PVDF β-phase, resulting in a decrease in the number of spherical nodules on the membrane surface, as well as improved density and smoothness. Consequently, this reduced fouling risk during membrane distillation while slightly decreasing membrane flux. On the other hand, acetone rapidly evaporated during the VIPS process, facilitating pre-gelatinization and α-phase formation of PVDF. This concurrent effect effectively restricted excessive nodule growth on the membrane surface, endowing the membrane with antifouling capabilities while preserving high flux.

A density surface model describing the habitat of the Critically Endangered Rice’s whale Balaenoptera ricei in the Gulf of Mexico

The newly recognized Rice’s whale Balaenoptera ricei is among the most endangered large whale species in the world and primarily occupies a region near the continental shelf break in the northeastern Gulf of Mexico (GoMex). We analyzed visual line-transect survey data collected throughout the northern GoMex from 2003-2019 and developed spatially explicit density maps using a density surface modeling approach to examine relationships between Rice’s whale density and bathymetric and oceanographic features. We identified water depth, surface chl a concentration, bottom temperature, and bottom salinity as key parameters that define the Rice’s whale habitat. This is consistent with upwelling of cold, high-salinity water along the continental shelf break and seasonal input of high-productivity surface water originating from coastal sources. The dominant circulation patterns in the GoMex, including the presence of Loop Current eddies, lead to increased productivity and likely play a role in maintaining high densities of forage species needed to support Rice’s whales. Extrapolation of the model suggests additional regions in Mexican waters of GoMex that may be suitable for Rice’s whales. This study informs the designation of critical habitat as defined by the US Endangered Species Act and will assist in marine spatial planning activities to avoid additional anthropogenic impacts to Rice’s whales associated with the development of wind energy and aquaculture.

Evaluation of underground gas storage capacity in the depleted gas reservoir with water evaporation and salt precipitation

Water evaporation and salt precipitation will occur in gas reservoirs and underground gas storage (UGS) with high-salinity formation water during production and operation. This phenomenon seriously affects the efficient and safe operation and gas storage capacity. This work focuses on quantitatively evaluating the UGS capacity based on depleted gas reservoirs considering water evaporation and salt precipitation. The core flooding experiments are conducted to analyze the influence of water evaporation and salt precipitation on rock properties under different water salinity during multi-cycle injection-production. A numerical model considering water evaporation is established to determine the salt precipitation radius around the gas well. According to the experimental and simulation results, a new analytical model is developed to calculate the underground natural gas storage capacity based on material balance principles. The field case study is presented to show the practical potential of the established model. Both formation porosity and permeability in near-well region may be finally improved by water evaporation and salt precipitation under irreducible water condition. In the presence of movable-water, formation porosity and permeability of the near-well region may be firstly improved and finally reduced due to continuous salt precipitation in porous media. Salt-precipitation radius achieves 28.5 m after ten cycles. The UGS capacity is 101.11 × 108 m3 without considering salt precipitation, 1.11% higher than original geological reserves. The UGS capacity considering both irreducible-water evaporation and salt precipitation is 101.03 × 108 m3. However, when the moveable-water evaporation volume increases to 15Virr, the final UGS capacity is further decreased to 98.55 × 108 m3. The UGS capacity has decreased by 0.82%, 1.64%, and 2.45% compared with irreducible water. The continuous evaporation of movable water and salt deposition will reduce the gas storage capacity and cause damage to the UGS. This work provides an effective method to investigate the quantitative impact of water evaporation and salt precipitation on UGS capacity.

Salinity Fronts in the South Atlantic

Monthly climatology data for salinity fronts in the South Atlantic have been created from satellite SMOS sea surface salinity (SSS) measurements taken from 2011–2019, processed at the Barcelona Expert Center of Remote Sensing (BEC), and provided as high-resolution (1/20°) daily SSS data. The SSS fronts have been identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS, computed using the Belkin–O’Reilly algorithm (BOA). The SSS gradient fields generated by the BOA have been log-transformed to facilitate feature recognition. The log-transformation of SSS gradients markedly improved the visual contrast of gradient maps, which in turn allowed new features to be revealed and previously known features to be documented with a monthly temporal resolution and a mesoscale (~100 km) spatial resolution. Monthly climatologies were generated and analyzed for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela Upwelling. A 2000 km-long triangular area between Africa and Brazil was found to be filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100 km wave length. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of meridional SSS maximum (Smax) was documented. The meridional Smax belt shifts north–south seasonally while retaining its well-defined linear morphology, which is suggestive of a yet unidentified mechanism that maintains this feature. The Subtropical Frontal Zone (STFZ) consists of two tenuously connected fronts, western and eastern. The Brazil Current Front (BCF) extends SE between 40 and 45°S to join the subantarctic front (SAF). The STFZ trends NW–SE across the South Atlantic, seemingly merging with the SAF/BCF south of Africa to form a single front between 40 and 45°S. In the SW Atlantic, the Rio de la Plata plume migrates seasonally, expanding northward in winter (June–July) from 39°S into the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The inner Plata front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter (June–July) from 53°S up to 39–40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the Angola–Benguela Front at 16°S. The Benguela Upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela Upwelling water forms a salinity front, which is separate from the thermal Angola–Benguela Front at 16°S. The high-salinity tropical water (“Angola water”) forms a wedge between the low-salinity waters of the Congo River outflow and Benguela Upwelling. This high-salinity wedge is bordered by salinity fronts that migrate north–south seasonally.

Nano structure of CO2-Brine-Kaolinite Interface: Implications for CO2 Geological Sequestration

CO2-Brine-Rock interaction has been identified to govern CO2 multiphase flow and affect the integrity of the underground reservoirs. However, limited investigations address the role of brine salinity, rock mineralogy, and organic matter in CO2 wettability at nano scale. To solve this problem, a molecular dynamics (MD) simulation is performed. The interfacial properties, including density distribution and radial distribution function (RDF, g(r)), are calculated for CO2 saturated high salinity water and CO2 saturated low salinity water. The density distribution profile shows that mineralogy is a critical parameter for CO2 wettability: lowering salinity leads to a more CO2 wet siloxane surface while the aluminol surface becomes less CO2 wet. g(r) reveals that the type of organic matter plays a critical role: base functional group (-N) renders a CO2 wet surface whereas the acid functional group (-COOH) causes a water wet surface. This investigation integrates the effects of brine salinity, mineralogy, and organic matter to evaluate CO2 wettability. This MD simulation reveals the principal factors controlling the CO2 wettability at the nano scale and provides a general paradigm to reduce the leakage risk of CO2 geological sequestration.

Climatic controls on water-mass chemistry in a Paleocene lacustrine setting, Subei Basin, eastern China

Abstract The Paleocene epoch was characterized by global climate fluctuations and major carbon-cycle perturbations. During the greenhouse climate that characterized the early Cenozoic, a short-lived late Paleocene global cooling event has been recognized from marine records. However, the response of the terrestrial system to this climate cooling event is poorly understood. Here, we present major- and trace-element analyses, iron speciation systematics, carbonate carbon isotope data, and mineralogical observations from lacustrine sediments in Member II of the Paleocene Funing Formation (E1f2), utilizing well-preserved drill core from the Subei Basin, eastern China. Both chemical (chemical index of alteration [CIA], Al/K ratios) and mineralogical (mineralogical index of alteration, clay/feldspar ratios) proxies yield consistent weathering and paleoclimatic interpretations, suggesting a transition from cool and arid climatic conditions to warmer and more humid climatic conditions. Correlation of carbon isotopes between the Subei Basin and deep-sea records implies that this terrestrial setting records the short-lived Paleocene climate cooling event. The combination of climate records and paleosalinity proxies (B/Ga and S/total organic carbon [TOC]) indicates a relatively high-salinity water column (brackish to saline) under cool and arid climatic conditions in the Subei Basin, suggesting that elevated salinity was likely produced via net-evaporative conditions, rather than marine incursions. A shift toward less saline brackish conditions up section reflects an increase in precipitation and freshwater runoff under warmer and more humid climatic conditions. Iron speciation and redox-sensitive trace-metal systematics reveal fluctuating redox conditions, from oxic through to anoxic ferruginous, but with the distinct development of better ventilated conditions as freshwater inputs increased under more humid conditions. Our findings demonstrate the sensitivity of terrestrial climate to the late Paleocene climate cooling event and further reveal the chemical response of a lacustrine setting to a cooling episode in a greenhouse world.

СОВРЕМЕННАЯ ГИДРОХИМИЧЕСКАЯ ХАРАКТЕРИСТИКА ВОДНЫХ ОБЪЕКТОВ КАЗАХСТАНСКОЙ ЧАСТИ БАССЕЙНА Р. ЕРТИС

The article presents materials from our own research on the study of the distribution of the mineralization, ionic composition, hardness, dissolved gases and pH values in various components of the river ecosystem of the Kazakhstan part of the Ertis river basin in the summer of 2023. It has been established that the water of the Black Ertis river is ranked in terms of mineralization to ultra-fresh, the value of total hardness – to soft, the content and ratio of the main ions - to the carbonate class, calcium group, the second type. Within the Pavlodar region, the concentration of the main salt-forming ions in the water of the Ertis River increases on average by 1.7...2.4 times, the water becomes fresh, the Alekin water index remains CCaII throughout the entire flow. The mineralization of water in the floodplain lakes Orlovskoye, Staritsa, Kurkol differs little from the water of the river Irtysh. The value of all studied indicators in the water of the Ertis River, its tributaries and lakes does not exceed the maximum permissible concentration. The water of all studied water bodies, with the exception of the storage lake Balkyldak, in terms of the content of standardized main ions and mineralization, belongs to quality class 1, is suitable for all types of water use and corresponds to “very good” quality. The wastewater storage tank Balkyldak has water of high salinity (19.42 g/dm3), very hard, highly metamorphosed sodium chloride composition of the third type and it can be recommended for the extraction of bischofite, halite and gypsum.

Designing MOFs/CuCo-LDHs hybrid-based superhydrophobic sponge for speedy eliminating microplastics, dyes, and oils from high-salinity water

It is urgent to develop effective materials to decontaminate wastewater owing to water scarcity in the whole world. In this study, we successfully fabricated a superhydrophobic and superoleophilic MOFs/LDHs based-functional sponge (OMCTS/ZIF-67/CuCo-LDHs@Sponge) with large specific surface area and high porosity for the first time through a two-step co-precipitation method and surface modification of polysiloxane. The polydopamine (PDA) molecules not only greatly improved the adhesion between coatings and substrate, but also enhanced growth of MOFs and LDHs structure. The in-situ growth of hexahedron ZIF-67 particles on multiple layered CuCo-LDHs sphere formed heterojunction, which significantly increased adsorption sites, specific area, and porosity and also solved the aggregation problem of powder MOFs. The CuCo-LDHs with large surface area was beneficial to ZIF-67 growth owing to same Co2+connection. The developed superhydrophobic sponge not only quickly and selectively absorbed various microplastics (MPs, as high as 500 mg/mL), dyes (C0 = 40 mg/L, removal rate of 99.6 %), and emulsified oils from high-salinity water with high capacity (e.g. 85 mg/g for PP-2000, 94 mg/g for PS-100, and 93 mg/g for PE-2000), but also exhibited outstanding synchronous decontamination capability for coexisting pollutants through multi-molecular synergistic mechanism and multiple adsorption forces (grasping force, strong capillarity, electrostatic interaction, hydrogen bonds, π-π interactions, p-π conjugation interaction. Van der Waals forces). The coated sponge showed superior mechanical durability, which still maintained separation ability above 98 % after repeated adsorption of MPs for 40 cycles. The adsorption mechanism was detailly investigated through theoretical simulation of adsorption energy. This coated sponge was destined to show broad and useful applications in water purification field.

Magnetically recyclable mesoporous carbon/zirconia composites for highly efficient removal of Cr(III) organic complexes from high salinity water: adsorption behavior and mechanism

ABSTRACT In this study, zirconia-functionalized magnetic core-shell mesoporous carbon composites (Fe3O4@C-ZrO2) were synthesized for the effective removal of Cr(III)-EDTA in high-salinity wastewater. Fe3O4@C-ZrO2 with Fe3O4 as a magnetic core and ZrO2 embedded in a mesoporous carbon skeleton were prepared by the sol-gel method in the nano-casting stage, which can be magnetically separated. The presence of ZrO2 on the adsorbents enhanced the adsorption of Cr(III)-EDTA and the maximum adsorption capacity of Fe3O4@C-ZrO2 was 16.21 mg·g−1 at pH = 3.0, which is remarkably higher than that of Fe3O4@C (3.65 mg·g−1). Fe3O4@C-ZrO2 has a strong anti-interference capability for cations in water, which can exhibit effective adsorption properties in presence of high concentration cations and anions (80 mmol·L−1) and high salt/complexant agent environments. Cr(III)-EDTA removal by adsorption of Fe3O4@C-ZrO2 was mainly through the formation of ternary complexes between ZrO2 in Fe3O4@C-ZrO2 and carboxylic acid groups in Cr(III)-EDTA. The Cr(III)-EDTA saturated Fe3O4@C-ZrO2 can be easily regenerated in 0.1 mol·L−1 NaOH than in 0.1 mol·L−1 HCl and still demonstrated an effective adsorption capacity for Cr(III)-EDTA after three repeated cycles. The results reflect the effective removal of Cr(III)-EDTA by Fe3O4@C-ZrO2 in high-salinity water, providing a new method for removing heavy metals in complex water.

Chemical grafting of hydrophobic functional groups on polyvinylidene fluoride side chain for vacuum membrane distillation applications

Membrane distillation has emerged as a promising technique for treating high-saline water. However, the process suffers from drawbacks such as wettability and fouling due to insufficient hydrophobicity of the membrane material. A practical approach for preparing hydrophobic membranes should involve improving surface roughness and chemistry manipulation. Herein, we explored chemical grafting of different functional groups viz. 1-(4-vinyl benzyl)azepane, N-(4-vinyl benzyl)decan-1-amine and 3-(triethoxysilyl)-N-(4-vinyl benzyl) propane-1-amine on polyvinylidene fluoride side chain to improve the hydrophobic characteristics and vacuum distillation performance (permeate flux and salt rejection). The successful grafting of hydrophobic functional groups on the polyvinylidene fluoride side chain was confirmed by spectral analysis such as 1H nuclear magnetic resonance, Attenuated total reflectance-Fourier transformation infrared spectroscopy, and X-ray photoelectron spectroscopy. The synthesised membranes were further characterised using morphology techniques (scanning electron microscopy, atomic force microscopy) for hydrophobicity (water contact angle, liquid entry pressure) and thermal and mechanical stability. The desalination performance of membranes was assessed by varying feed concentration (2–8 % NaCl) and feed temperature (30–75 °C). The 3-aminopropyltriethoxysilane grafted vinyl benzyl polyvinylidene fluoride membrane exhibited the highest flux (20.35 L m−2 h−1), salt rejection (99.99 %) at 4 % NaCl feed concentration and 60 °C feed temperature attributed to a well-arranged large number of pores and its hydrophobicity. The 3-aminopropyltriethoxysilane grafted membrane exhibited the highest anti-fouling characteristic. Further, high flux and salt rejection of the synthesised membranes for vacuum membrane distillation operation were compared to membranes reported in the literature, demonstrating its potential for high saline water desalination.

Surface modification of nanofiltration membrane using quaternary diethanolamine for efficient antibiotics/salt separation

Nanofiltration plays a crucial role in antibiotic desalination from high salinity water, but the membranes often have low water permeability and insufficient selectivity between antibiotics and salts. In this study, a Gemini-type quaternary diethanolamine monomer (QTDEA) containing quaternary ammonium and hydroxyl groups was synthesized. This monomer had a hybrid spatial structure combining both rigid and flexible components, allowing it to covalently graft to the acyl chloride groups on the nascent polyamide (PA) film. The resulting modified PA-QTDEA membrane exhibited enhanced hydrophilicity, reduced negative charge, and a looser structure. It demonstrated a high water permeance of 18.2 L m−2 h−1·bar−1 for chlortetracycline hydrochloride (CTC) desalination from a NaCl solution of 10 g L−1, and the NaCl/CTC selectivity was 21.2. This research presents an efficient method for improving the performance of antibiotic desalination through surface modification using the novel QTDEA monomer.

Comprehensive investigation of capacitive deionization cells by response surface methodology

Freshwater resources are limited; thus, different technologies for desalination of brackish and seawater have been developed. Capacitive deionization (CDI) is one of the most promising desalination technologies owing to its low cost, simplicity, nonmoving parts, and low energy consumption. However, its energy consumption significantly increases with desalination of high-salinity water. In this regard, a good understanding of the effects of different process parameters on CDI energy consumption is crucial for further performance improvement. Therefore, the surface response methodology (RSM) was adopted to systematically study the effects of applying voltage, Stern layer capacity, volume and concentration of feed water, and volume of micropores on energy consumption and desalination time. The results showed that the Stern layer capacity and volume of micropores reduced desalination time by approximately 25% without significant changes in energy consumption. With the design of an improved electrode (improving the micropore structure for ion adsorption), the desalination time (Cycle) was reduced and a slight reduction in energy consumption was achieved. It can be claimed that any improvement in the physical (porosity) and electrical properties of the electrodes, results in an important increase in the performance of the CDI system.

Utilizing Hybrid RO-OARO Systems as New Methods for Desalination Process

The scarcity of fresh water and its essential role in sustaining life on Earth have motivated researchers to seek new, low-cost, scalable technologies for water desalination. Therefore, the osmotically assisted reverse osmosis (OARO) membrane process presents an innovative approach to achieve moderate water recoveries from high salinity water without undergoing a phase change. This work aims to investigate the performance of hybrid RO-OARO systems with various designs and operational parameters on recovery and R%. The hybrid systems were evaluated for 60 minutes at feed concentrations of 3.98-5.54 g/l, applied pressures ranging from 3 to 7 bars, and different membrane types. The results showed that the flux of the hybrid system increased by increasing the pressure and decreased by increasing the feed concentration. The highest recovery value was obtained for the RO-OARO system at an RO pressure of 7 bar and an OARO unit at 3 bar for a 3.98 g/l feed concentration. In contrast, when the reverse osmosis pressure was fixed at 5 bar, and the pressure of the OARO unit increased by 2 bar, the recovery value exceeded by about 6%. Furthermore, the FilmTech membrane showed the highest recovery at 31.7%, while the highest R% was 94.55% for the AquaTec membrane. The RO-OARO-OARO system contributed to increasing both the recovery and rejection values by 11.4 and 2.1%, respectively, compared with the RO-OARO system. The experiments in this study revealed a slight increase in the feed concentration of the reverse osmosis unit, indicating the efficiency of the hybrid systems compared to traditional RO systems.

Tipping of the double-diffusive regime in the southern Adriatic Pit in 2017 in connection with record high-salinity values

Abstract. In double-diffusive mixing, whenever salinity and temperature decrease with depth, the water column is either unstable or predisposed to a state called salt fingering (SF), which exhibits increased vertical mixing. Analysis of a high-frequency time series of thermohaline data measured at the EMSO-E2M3A regional facility in the southern Adriatic Pit (SAP) from 2014 to 2019 reveals that in the south Adriatic, SF is the dominant regime. The same time series shows the presence of a very saline core of the Levantine Intermediate Water that penetrated with unprecedented strength during the winter of 2016/17 at around 550 dbar and even higher-salinity water above. The effect of strong heat loss at the surface during that winter allowed deep convection to transport this high-salinity water from the intermediate to the deep layers within the pit. This resulted in an increased predisposition to SF throughout the water column. In the subsurface layer (350 to 550 dbar) the increase is from 27 % to 72 % of observations. We observe an alteration of vertical stratification throughout the water column during the winter of 2016/17 from a stratified water column to an almost homogeneous water column down to 700 dbar, with no return in the following years.

Are winter conditions impacting annual organic production in the northern Adriatic? Verifications and future projections

Primary production in the northern Adriatic (NAd) reaches its yearly peak in the winter with high-intensity variations from year to year. According to the hypothesis, the intensity of local winter primary production, controlled by the degree of the spreading of Po River waters across the NAd, reflects on the annual secondary production of the ongoing year. The hypothesis is evaluated here based on the new data set and extends from 2018 to 2020, referring additionally to 2017 data which are already published. Data collected in 2017 and 2020 support the hypothesis, pointing to the large organic outputs after highly productive winters. Despite the lack of seasonal data for 2018 and 2019, large annual production was deducted by large abundances of the allochthonous gelatinous zooplankton species – Mnemiopsis leidyi. Numerical models show that in 2018–2020 the NAd was mostly “separated” from the rest of the Adriatic Sea by a northern branch of a large cyclonic gyre with high salinity water (from central Adriatic and/or Kvarner Bay) entering the NAd along the eastern (Istrian) coast. Such a circulation system could favour the spreading of the Po River waters across the NAd, inducing high primary production in winter, at the beginning of the yearly pelagic cycle, with a subsequent retention/accumulation of organic matter produced in the following months in the area. Using climate projections of temperature and salinity and the associated circulation and following the observed biological relations, a prediction of the organic matter production in the NAd can be obtained. With increased horizontal density gradients in future winters, an intensification of transversal motions across the NAd is expected. Thus, the retention of the Po waters with higher winter production in the NAd may be predicted. Following the hypothesis, a higher annual organic production and a probable higher occurrence of gelatinous plankton in the east of the NAd are expected.