Hypersaline Brines Research Articles

Synergy of feed-side aeration and super slippery interface in membrane distillation for enhanced water flux and scaling mitigation

Membrane distillation (MD) is an acknowledged promising technology for desalinating hypersaline brine, and as such can be a suitable candidate to further concentrate the seawater discharged from reverse osmosis process. Mineral scaling represents a major constraint against the application of MD for further desalination of concentrated seawater, especially when considering CaSO4 (gypsum) and NaCl. Up until now, it has been difficult to rely solely on membrane modification to mitigate CaSO4 scaling. Permeate-side aeration can lessen CaSO4 scaling, but does not permit to increase the water flux. Herein, we proposed the synergy of feed-side aeration and super slippery interface to perform concentrated seawater desalination via direct contact membrane distillation. The results of this study show that this synergistic effect could significantly increase the water flux, which was approximately 1.5 times higher in comparison to the membrane without aeration. Moreover, the synergistic effect effectively alleviates the complex scaling of concentrated seawater, achieving 90 wt% water recovery rate. Based on the observed results, we elucidated the mechanisms governing the enhanced water flux and scaling mitigation driven by the synergistic effect. In addition, we studied the optimal working condition for this system, unveiling that low-intensity large bubbles are more suitable as they lead to a better equilibrium between the economics and functionality of the process.

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Solar‐driven interfacial evaporation received extensive attention due to their potentials in water, energy and environmental sustainability. However, accumulation of salts are major challenges for solar desalination. Gan et. al. reported a self‐salt‐cleaning architecture to realize a maintenance‐free operation for hypersaline brines, paving the way towards zero‐liquid‐discharge treatment of hypersaline water from reverse osmosis systems, and accelerated salt mining for batteries. image

A gas hydrate process for high-salinity water and wastewater purification

This study investigates the effectiveness of a hydrate-based water purification process on high-salinity and wastewater samples. Testing involved a 4-L-scale novel apparatus using HFC134a as a guest molecule during a continuous hydrate formation–pelletization–dissolution process. Each stage of the succeeded in removing 80–85% of individual dissolved contaminants from highly polluted water. This is the first study to meaningfully demonstrate the ability to purify highly polluted water by applying the proposed method to water with very high concentrations of salts or sugars that exceed the range treatable by reverse osmosis. In a single-stage hydrate process with no pre-or and post-treatment, the average removal efficiencies of ionic compounds in seawater, hypersaline brine (total dissolved solid ⁓150,000 mg/L) and contaminants from wastewater (Coca-Cola beverage, chemical oxygen demand ⁓80,000 mg/L) were 89%, 80%, and 81%, respectively. This study illustrates the effective and economic application of the proposed method and apparatus to the purification of high-salinity water and wastewater under various conditions.

Spatial extent of desalination discharge impacts to habitat-forming species on temperate reefs

Outlet infrastructure and hypersaline discharge from large-scale desalination operations have the potential to impact marine environments. Here, we present the results of a six-year M-BACI assessment of the impacts of desalination discharge outlet construction and hypersaline effluent on the cover of habitat-forming species on temperate reefs. The construction of the desalination outlet caused a decrease in the cover of Ecklonia radiata (kelp) and an increase in the cover of algal turfs up to 55 m from the outlet. Following the commencement of discharging of hypersaline brine, the impact to E. radiata and algal turfs persisted, but decreased in spatial extent to be less than 25 m from the outlet. Hypersaline discharge was also associated with a significant decline in the cover of sponges in outlet compared to reference sites. Overall, our results demonstrate that the water security benefits from large-scale desalination may sometimes be appropriately balanced against the associated ecological consequences.

Thermodynamics of solvent-driven water extraction from hypersaline brines using dimethyl ether

Solvent-driven water extraction (SDWE) has promising applications in hypersaline brine desalination, including zero-liquid discharge processing for industrial wastewaters, and resource recovery, such as the extraction of lithium and rare earth elements from solution mining leachates. In this study, we develop a computational thermodynamic framework to analyze the liquid–liquid extraction of water from hypersaline brines using dimethyl ether (DME), an aprotic solvent that is partially miscible with water. The high volatility of DME enables its rapid separation from water–DME mixtures after water absorption, while its low polarity minimizes the organic-phase solubility of electrolytes, such as sodium chloride (NaCl). We first build a thermodynamic model based on the LIQUAC excess Gibbs free energy model for water–DME–NaCl mixtures. Maximum likelihood estimators for water–DME–NaCl interaction parameters are calculated through the nonlinear regression of fluid phase equilibrium and osmotic coefficient data using metaheuristic global optimization techniques. A multistage counter-current liquid–liquid separator (LLS) model is then developed to explore the water recovery and brine concentration ratios achievable as a function of feed molality and DME to feed water flow rate ratio. For a saline feed with a molality of 2.0molkg−1 (over three times the salinity of seawater) our analysis demonstrates that a one-stage LLS can achieve a water recovery ratio of 0.51 with an initial DME to saline feed molar flow rate ratio of 4.0, rising to 0.63 with a second equilibrium stage. We conclude by quantifying the amount of DME required to reach zero-liquid discharge brine salinities and analyzing the impact of staging and temperature on separation performance. Our thermodynamic model enables the rapid evaluation of SDWE systems for emerging hypersaline brine desalination and valorization applications.

A self‐salt‐cleaning architecture in cold vapor generation system for hypersaline brines

AbstractDesalination of seawater with zero‐liquid discharge is a major challenge. Here we developed a three‐dimensional “umbrella” architecture to evaporate hypersaline brines of up to 20 wt% using solar‐driven interfacial evaporation. By controlling the water pathway and the thickness of the evaporator films to manipulate the salt capacitance of the system, a stable evaporation rate of >2.6 kg m−2 h−1 was achieved over 4‐day operation in the laboratory environment with minimized salt accumulation on evaporation surfaces. By placing the system in an outdoor environment with natural wind, the peak evaporation rate was improved to 9.05 kg m−2 h−1. After a 4‐day outdoor test, the total evaporated water by the umbrella system was 3.7× more than the natural evaporation from a bulk water surface under identical environmental conditions. The predesigned water flow also controlled the local salt accumulation, resulting in easier salt removing and collection, which is highly desired for accelerated salt mining applications.image

Tuning interlayer structure to construct steady dual-crosslinked graphene oxide membranes for desalination of hypersaline brine via pervaporation

Graphene oxide (GO) membranes have shown great potential in desalination. However, it is still a challenge to tune the interlayer structure of GO and suppress its swelling in water to realize superior separation performance and enhance the mechanical stability of membrane. Herein, polyethyleneimine (PEI) with different molecular weight was employed to crosslink GO nanosheets and tune interlayer spacing of lamellar GO membrane for desalination of hypersaline brine by pervaporation (PV). A dual crosslinking structure was performed via electrostatic interaction and covalent bonding between PEI and GO rendering effectively restricted swelling of GO. The interlayer spacing was adjusted by tuning PEI molecular weight and the surface charge of GO membrane was converted to positive to repel ions. The membrane crosslinked with larger PEI (c-GO-PEI 70k) exhibited the most robust structure and showed outstanding PV desalination performance with high water flux of 86.0 kg/m2 h and salt rejection of 99.99% in treating 10 wt% NaCl hypersaline solution at 90 °C. This work provides further understanding of regulating interlayer structure and constructing high-performance GO membranes for PV desalination.

Impact potential of hypersaline brines released into the marine environment for CCS reservoir pressure management

The environmental impact potential arising from the possible disposal of hypersaline brines into the ocean as part of reservoir pressure management for Carbon Capture and Storage is assessed using sophisticated high-resolution hydrodynamic models for the first time, investigating several industry guided scenarios. Although the characteristics of some brines in their undiluted form would have a high environmental impact potential, we find that dispersion in a hydrodynamically active region like the North Sea acts to dilute disposed brine rapidly, even in a worst case approach, such that the potential impact footprint (area exposed to environmentally damaging salinity or temperature) is small, measured in 10′s of meters depending on the release scenario and site specific data such as the hypersaline water contaminants along with in-situ conditions such as currents and mixing. The method of brine disposal has a significant influence on dispersal, such that brines released nearer the sea surface disperse more rapidly, compared with release at the seabed. Hence consideration of brine release height is recommended to further limit impact potential.

Desirable PVDF hollow fiber membrane engineered with synergism between small molecular weight additives for DCMD treating of a hypersaline brine

Developing membrane for brine waste reclamation via direct contact membrane distillation (DCMD) requires specially membrane characteristics engineering. Toward practical and scalable hydrophobic micromembrane with desirable properties, attaining energy-efficient and durability during hypersaline treatment remains a great challenge. Herein, polyvinylidene fluoride (PVDF) hollow fiber (HF) membranes were developed for particular use in DCMD for treating hypersaline (100,000 mg/L of NaCl solution) via adopting mixture of small molecular weight (MW) additives, including water, lithium chloride (LiCl), and ethylene glycol (EG). Engineered to suppress the limitation of single small MW additives only possessing a unique enhancement in the tailoring of specific properties for improving the partial DCMD performance, the research emphasis is placed on the synergistic effect between small molecular weight additives, resulting in a much-enhanced performance. The dope solution of PVDF/LiCl/H2O/N-Methyl-2-pyrrolidone (NMP) = 12/2/2/84 (wt%) spun HF membrane, P-L-W2, has been shown to reveal the most desirable membrane characteristics for DCMD, including comparable porosity (ε, 74.2 ± 0.4%), superior liquid entry pressure (LEP, 3.05 bar), and robust mechanical properties. The P-L-W2 membrane also exhibited enhanced water flux, energy efficiency, and anti-wetting ability in comparison with the neat PVDF HF membrane. With advantage of easy implement, the concept of adoption of additives mixture provides a novel platform to customize desirable PVDF HF membranes with enhanced DCMD performance.

Negative Pressure Membrane Distillation for Excellent Gypsum Scaling Resistance and Flux Enhancement

Membrane distillation (MD) has potential to become a competitive technology for managing hypersaline brine but not until the critical challenge of mineral scaling is addressed. The state-of-the-art approach for mitigating mineral scaling in MD involves the use of superhydrophobic membranes that are difficult to fabricate and are commercially unavailable. This study explores a novel operational strategy, namely, negative pressure direct contact membrane distillation (NP-DCMD) that can minimize mineral scaling with commercially available hydrophobic membranes and at the same time enhance the water vapor flux substantially. By applying a negative gauge pressure on the feed stream, NP-DCMD achieved prolonged resistance to CaSO4 scaling and a dramatic vapor flux enhancement up to 62%. The exceptional scaling resistance is attributable to the formation of a concave liquid-gas under a negative pressure that changes the position of the water-air interface to hinder interfacial nucleation and crystal growth. The substantial flux enhancement is caused by the reduced molecular diffusion resistance within the pores and the enhanced heat transfer kinetics across the boundary layer in NP-DCMD. Achieving substantial performance improvement in both the scaling resistance and vapor flux with commercial membranes, NP-DCMD is a significant innovation with vast potential for practical adoption due to its simplicity and effectiveness.

In situ U-Pb dating and geochemical characterization of multi-stage dolomite cementation in the Ediacaran Dengying Formation, Central Sichuan Basin, China: Constraints on diagenetic, hydrothermal and paleo-oil filling events

Improved understanding of subsurface paleo-fluid circulation history can assist in reconstructing associated pore evolution of carbonate reservoirs. Multi-stage dolomite cements generated by basinal fluids over time were investigated using a combination of petrography, geochemistry, fluid-inclusion studies, LA-ICP-MS U-Pb geochronology, and seismic interpretation. This study aims to gain clues about diagenetic, hydrothermal and paleo-oil filling events within the Ediacaran Dengying Formation, Sichuan Basin, China.Four main phases of dolomite cementation were petrographically, geochemically and geochronologically distinguished that can be ascribed to major tectonic events throughout the basin evolution. The earliest dolomite generation occurs as fibrous dolomite crust (FDC) growing along the karst vug wall, interpreted as marine diagenetic cement formed in a submarine environment during the Late Ediacaran, most likely from the influx of seawaters following the uplift and subaerial exposure related to the Tongwang movement. In situ U-Pb ages obtained from the other three generations of cement dolomites are interpreted to coincide with the timing of repeated strike-slip fault movements as indicated by the seismic data, suggesting a direct link between cement emplacement and regional tectonic-thermal events. Sub-vertical extension dolomite veins (EDV), representing the second generation, are considered as being syntectonic, generated from slightly modified connate seawaters at a shallow to moderate burial depth in a transtensional stress regime during the Cambrian taphrogenesis. Two generations of saddle dolomite cements, SD1 and SD2, have recorded two major episodes of hot fluids circulating in the Dengying Formation. The SD1, filling in hydraulic fractures and vugs, formed during the third phase of cementation, as a result of a hydrothermal event associated with Caledonian exhumation. Deep-seated hot brines squeezed into the Dengying reservoirs along the sub-vertical strike-slip faults combined with some meteoric waters that percolated downward, are deemed responsible for precipitating SD1. The SD2 is the youngest cement present, which is interpreted to have formed during the ingress of deeper, hot, hypersaline brines arising from the late Permian hydrothermal activity likely triggered by the eruption of Emeishan flood basalts.Cross-cutting relationships between bitumen phases and different dolomite generations indirectly define the dates of two paleo-oil charging events. The first episode of paleo-oil charging occurred during the Late Ediacaran to Early Cambrian, likely sourced from underlying Ediacaran Doushantuo shales. Late oil emplacement occurred after the Late Permian, in agreement with the reported bitumen Re-Os age and the age inferred through fluid-inclusion analysis. Primary source rocks generating this phase of oil were considered as the Cambrian Qiongzhusi shales, because basin modeling-derived date of oil window matches with the second oil filling time.

Direct dating Paleo-fluid flow events in sedimentary basins

Reconstructing fluid evolution history in old sedimentary basins is extremely challenging due to the prolonged evolution, lack of exact age constraints and absence of preserved fluids. By integrating in-situ calcite UPb dating, fluid inclusion analysis, measurements of major and trace elements and carbon‑oxygen‑strontium isotopes, and molecular composition analysis of petroleum, we have reconstructed the fluid evolution history during the Carboniferous in an Ordovician deeply-buried carbonate reservoir in the Tarim Basin, China, with unprecedented temporal resolution. Five generations of calcite cementation spanning over 37 m.y. are dated in a single calcite vein with UPb ages ranging from ~353 Ma to ~316 Ma. The initial cement was associated with an intrusion of hyper-saline brine, enriched in REEs. This was followed by influx of meteoric water to precipitate the second and third generations of cement, which are characterized by reduced salinity, anomalously high 87Sr/86Sr ratios and extremely low concentration of REEs. The fourth generation of calcite cement was formed in a deep-fluid system accompanied by oil charge as indicated by the presence of bitumen, oil inclusions and low δ13C and 87Sr/86Sr ratios. The fifth generation of cement was precipitated from equilibrated connate water, and has the lowest salinity and a comparable REE signature to the host rock. Oil charge event occurred around 326 Ma. This study demonstrates the effectiveness of combining in-situ calcite UPb geochronology, fluid inclusion analysis, elemental and isotopic geochemistry to elucidate high-resolution temporal fluid evolution in old sedimentary basins with a complex tectonic history, providing a new paradigm for studying geofluid evolution.

Characterization of hydrothermal fluids that alter the upper oceanic crust to spilite and epidosite: Fluid inclusion evidence from the Semail (Oman) and Troodos (Cyprus) ophiolites

Pervasive alteration of basaltic oceanic crust by heated seawater at greenschist facies conditions produces two contrasting hydrothermal rocks. “Spilites”, consisting of chlorite + albite + quartz ± actinolite ± epidote, occur typically with regional extents. Locally spilites are metasomatically transformed to “epidosites” consisting of epidote + quartz + titanite + hematite or magnetite. Both alteration types have been proposed as markers of deep hydrothermal upflow in sub-seafloor convection cells, and as sources of the ore metals in basalt-hosted seafloor massive sulfide deposits. Little direct evidence is available for the chemical compositions of these fluids in their states deep in the upflow zones prior to their discharge at the seafloor. To better characterize them we have conducted a field, petrographic and fluid inclusion study of the lavas, sheeted dikes and plagiogranites in the Semail ophiolite, with supporting samples from the Troodos ophiolite. Our results show that both the spilite- and epidosite-forming fluids were single-phase aqueous liquids during the hydrothermal alteration. At some sites their salinity is 3.1–3.2 wt.% NaCleq, which we take to represent the chlorinity of Cenomanian seawater in the Semail realm. At other sites salinities are as low as 2.4 wt.% NaCleq or as high as 5.7 wt.% NaCleq, attributable to liquid–vapor separation and partial remixing deep in the crust along the dew curve of seawater, prior to ascent of the fluids to the sites of fluid inclusion trapping. Hypersaline brines, often accompanied by vapor, are restricted to plagiogranites in both the Semail and Troodos ophiolites and they represent magmatic–hydrothermal fluids that pre-date and are genetically unrelated to the spilite and epidosite alteration. The volcanostratigraphic locations of the samples constrain their maximum depths to 1470–3600 m below seafloor during alteration. The range of possible fluid trapping pressures for all samples is 31–68 MPa. Trapping temperatures vary between sites from 145 to 440 °C for spilite fluids and 255 to 435 °C for epidosite fluids. Quantitative analyses of 12 elements in individual fluid inclusions by LA-ICP-MS define the chemical characters of the two alteration fluids. The Br/Cl ratio in the spilite fluid is the same as in modern seawater and the other elements fit expectations from seawater–basalt experiments at elevated temperature. Accordingly, concentrations of Li, B, Na, Cl, K, Br and Sr in the spilite fluid match those in modern black-smoker vent fluids in basaltic crust. Exceptions are Ca and Fe, which are enriched in the spilite fluid. As these elements may precipitate below or at the seafloor prior to vent sampling, we conclude that the spilite fluids are plausible feeders of basalt-hosted black-smoker vents. The epidosite fluid has broadly similar elemental concentrations to the spilite fluid, but vastly lower Fe, reflecting the highly oxidized state of epidosites. This suggests that epidosite fluids are incapabable of forming basalt-hosted seafloor massive sulfide deposits.

High-rate long-lasting solar desalination towards hypersaline brine enabled by introducing a siphon-drop mode

Direct solar steam generation (DSSG) is well-proven to be a sustainable and effective technique to provide high-quality freshwater supply. However, it customarily suffers from severe salt accumulation, especially for treating strong brine, becoming a fatal bottleneck for approaching its commercial applications. Herein, we developed a DSSG with potent siphon-drop mode to achieve powerful self-absorbing and self-desalting, in which the 3D cone-shaped self-supporting polydopamine and polyethyleneimine co-coated poly(acrylonitrile-styrene-acrylate) (PDA-PEI@ASA) used as photothermal material (PTM). Source water can be spontaneously and continuously pumped to the top of water-evaporating surface of PTM via strong siphon effect, and the top-down active water diffusion on evaporating surface can effectively take the salts away from the system. Such above features give the DSSG real-time antifouling nature and hence address the fatal issue of salt accumulation. Accordingly, when continuously treating a near-saturated brine (20% NaCl) for at least 168 h, no obvious salts deposition can be found with a steady water evaporation rate of ∼2.550 kg m–2 h−1. This work could help shed novel light on the design of practical DSSG systems toward efficient lasting freshwater extraction, holding great promise for global water scarcity.

Solar‐driven brine desalination and concentration by controlled salt excretion

AbstractDesalination technology provides one promising solution to the global water shortage problem yet brings about a new challenge of managing massive waste brines. Recently, interfacial solar steam generation technology has gained increasing attention for brine treatment due to its high energy‐conversion efficiency and applicability to hypersaline brines. However, it is challenging to maintain high performance because of salt fouling problem. Herein, this study presents a novel salt excretion approach to maintaining the evaporation efficiency of interfacial solar steam systems for improved long‐term stability in brine desalination. By creating a directional flow, accumulated salts are excreted via discharging the concentrated brine. This approach is effective and applicable for brines with a broad range of concentration owing to its tuneable concentrating performance. With the capability of continuously producing clean water and near‐saturation brine, this work advances solar steam technologies toward practical applications, such as brine concentration and resource recovery.image

All-Polymer and Self-Roughened Superhydrophobic PVDF Fibrous Membranes for Stably Concentrating Seawater by Membrane Distillation.

Novel specially wettable membranes have been attracting significant attention for durable membrane distillation (MD). However, constructing a superhydrophobic interface often has to undergo complex modification procedures including roughness construction and hydrophobic modification. Herein, all-polymer and self-roughened superhydrophobic poly(vinylidene fluoride) fibrous membranes (PVDF FMs) with robustly stable pores were successfully constructed via electrospinning of fluorinated polyhedral oligomeric silsesquioxanes/PVDF (F-POSS/PVDF) emulsion solution in combination with hot-pressing. The comparative experiment reveals that proper hot-pressing, including adequate temperature and pressure, can help improve membrane pore stability by welding the intersecting fibers and increase the membrane surface hydrophobicity by transferring the inner fluorine chains to the outer fiber surface, simultaneously advancing membrane scaling and fouling resistance. Nevertheless, excessive temperature or pressure will destroy the interconnected pores and surface wettability of the PVDF FM. Significantly, the hot-pressing-treated F-POSS/PVDF FM shows a high water recovery (∼90%) and robust stability after five rounds of the concentration process toward concentrating natural seawater as a target. Thus, the all-polymer and self-roughened superhydrophobic PVDF FMs constructed via electrospinning combined with the thermal treatment have potential applications in concentrating hypersaline brines, which make up for the other membrane technology, including reverse osmosis and nanofiltration technologies that failed to concentrate hypersaline solutions.

Periodically Released Magmatic Fluids Create a Texture of Unidirectional Solidification (UST) in Ore-Forming Granite: A Fluid and Melt Inclusion Study of W-Mo Forming Sannae-Eonyang Granite, Korea

The Upper Cretaceous Sannae-Eonyang granite crystallized approximately 73 Ma and hosted the Sannae W-Mo deposit in the west and the Eonyang amethyst deposit in the east. The granite contained textural zones of miarolitic cavities and unidirectional solidification texture (UST) quartz. The UST rock sampled in the Eonyang amethyst mine consisted of (1) early cavity-bearing aplitic granite, (2) co-crystallization of feldspars and quartz in a granophyric granite, and (3) the latest unidirectional growth of larger quartz crystals with clear zonation patterns. After the UST quartz was deposited, aplite or porphyritic granite was formed, repeating the prior sequence. Fluid and melt inclusions occurring in the UST quartz and quartz phenocrysts were sampled and studied to understand the magmatic-hydrothermal processes controlling UST formation and W-Mo mineralization in the granite. The composition of melt inclusions in the quartz phenocrysts suggested that the UST was formed by fractionated late-stage granite. Some of the melt inclusions occurring in the early-stage UST quartz were associated with aqueous inclusions, indicating fluid exsolution from a granitic melt. Hypersaline brine inclusions allowed the calculation of the minimum trapping pressure of 80–2300 bars. Such a highly fluctuating fluid pressure might be potentially due to a lithostatic-hydrostatic transition of pressure-attending fluid loss during UST formation. Highly fluctuating lithostatic-hydrostatic pressures created by fluid exsolution allowed shifting of the stability field from a quartz-feldspar cotectic to a single-phase quartz. The compositions of brine fluid assemblages hosted in the quartz phenocrysts deviated from the fluids trapped in the UST quartz, especially regarding the Rb/Sr and Fe/Mn ratios and W and Mo concentrations. The study of melt and fluid inclusions in the Eonyang UST sample showed that the exsolution of magmatic fluid was highly periodic. A single pulse of magmatic fluids of variable salinities/densities might have created a single UST sequence, and a new batch of magmatic fluid exsolution would be required to create the next UST sequence.

Liquid-like surface modification for effective anti-scaling membrane distillation with uncompromised flux

Membrane scaling is a critical challenge for membrane distillation (MD), especially when treating hypersaline brines. In this study, an anti-scaling membrane was developed with a liquid-like surface coating. This fabrication approach combined electrospun polyvinylidene fluoride (PVDF) membrane with surface fluorination without the addition of nanoparticles. Two fluoro silanes with the same alkyl-chain length but different hydrolysis reaction sites were investigated as the fluorination agents. Membrane characterizations indicated that surface modification with the single hydrolysis site fluoro silane (17-FAS-S) did not change the membrane morphology or structure. On the other hand, surface modification with the triple hydrolysis site fluoro silane (17-FAS-T) generated nanoparticles on the membrane surface, resulting in increased roughness. While both the 17-FAS-S and 17-FAS-T modified membranes exhibited excellent scaling resistance in the MD scaling tests, the 17-FAS-S membrane provided a much higher vapor flux than the 17-FAS-T one. Finally, the mechanism of scaling resistance and vapor permeability provided by the liquid-like modification was discussed.

Design principles and challenges of bench-scale high-pressure reverse osmosis up to 150 bar

High-pressure reverse osmosis (HPRO) has been recently proposed for the energy-efficient desalination of hypersaline brines. To advance this technology, substantial innovation is needed, including the capacity to test membranes at ultra-high hydraulic pressures. Here, we report on the development of an apparatus designed and constructed specifically for coupon-scale membrane research in HPRO. The capabilities of the closed-loop crossflow system were demonstrated through desalination experiments at hydraulic pressures up to 150 bar and feed concentrations up to 2.0 M (117 g L−1) NaCl. Several safety-related design considerations are highlighted in addition to the design of a custom-built membrane test cell and high-pressure seal to ensure leak-free, safe operation. Corrosion control protocols were also developed to enable long-term system compatibility with corrosive hypersaline feed solutions. Lastly, we highlight novel experiments that are now possible with this apparatus and discuss the benefit it represents to HPRO development by the membrane community.

Divergent Genomic Adaptations in the Microbiomes of Arctic Subzero Sea-Ice and Cryopeg Brines.

Subzero hypersaline brines are liquid microbial habitats within otherwise frozen environments, where concentrated dissolved salts prevent freezing. Such extreme conditions presumably require unique microbial adaptations, and possibly altered ecologies, but specific strategies remain largely unknown. Here we examined prokaryotic taxonomic and functional diversity in two seawater-derived subzero hypersaline brines: first-year sea ice, subject to seasonally fluctuating conditions; and ancient cryopeg, under relatively stable conditions geophysically isolated in permafrost. Overall, both taxonomic composition and functional potential were starkly different. Taxonomically, sea-ice brine communities (∼105 cells mL–1) had greater richness, more diversity and were dominated by bacterial genera, including Polaribacter, Paraglaciecola, Colwellia, and Glaciecola, whereas the more densely inhabited cryopeg brines (∼108 cells mL–1) lacked these genera and instead were dominated by Marinobacter. Functionally, however, sea ice encoded fewer accessory traits and lower average genomic copy numbers for shared traits, though DNA replication and repair were elevated; in contrast, microbes in cryopeg brines had greater genetic versatility with elevated abundances of accessory traits involved in sensing, responding to environmental cues, transport, mobile elements (transposases and plasmids), toxin-antitoxin systems, and type VI secretion systems. Together these genomic features suggest adaptations and capabilities of sea-ice communities manifesting at the community level through seasonal ecological succession, whereas the denser cryopeg communities appear adapted to intense bacterial competition, leaving fewer genera to dominate with brine-specific adaptations and social interactions that sacrifice some members for the benefit of others. Such cryopeg genomic traits provide insight into how long-term environmental stability may enable life to survive extreme conditions.