Water recovery from brines and salt‐saturated solutions: operability and thermodynamic efficiency considerations for desalination technologies

Vane, Leland M.

doi:10.1002/jctb.5225

Cited by 34 publications

(22 citation statements)

References 46 publications

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“…Thermal separation processes such as mechanical vapor compression (MVC) are often used for such applications [3,4], since desalination up to saturation concentration is possible in these systems at low pressures and temperatures (< 100 • C). More recently, humidification dehumidification desalination (HDH) [5,6,7,8] has been developed as simple, low capital-cost thermal technology for treating ultra-saline produced waters [9,10].…”

Section: Context: Desalination Up To High Salinitymentioning

confidence: 99%

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

et al. 2018

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This study presents a comprehensive analytical framework to design efficient single-stage membrane distillation (MD) systems for the desalination of feed streams up to high salinity. MD performance is quantified in terms of energy efficiency (represented as a gained output ratio, or GOR) and vapor flux, both of which together affect the specific cost of pure water production. Irrespective of the feed salinity, permeate or conductive gap MD (P/CGMD) performs better than direct contact MD (DCMD) when the heat transfer resistance of the gap (in P/CGMD) is lower than that of the external heat exchanger in DCMD. Air gap MD's (AGMD) better performance relative to the other configurations at high salinity and large system area can be explained in terms of its thicker 'effective membrane', which includes the air-gap region. CGMD and DCMD employing a thick membrane are also resilient to high salinity, similar to AGMD, while not being susceptible to the gap flooding that can harm AGMD's performance. A method is described to simultaneously determine the cost-optimal membrane thickness and system size as a function of the ratio of specific costs of heat energy and module area. At low salinity and small system size, GOR rises and flux declines with an increase in membrane area. For salty feed solutions, there exists a critical system size beyond which GOR also begins to decline. Since both GOR and flux are lower, no economic rationale favors operation above this critical size, irrespective of the costs of thermal energy and system area. A closed-form analytical expression for this critical system area is derived as a function of the feed salinity and two dimensionless ratios of heat transfer resistances within the MD module.Keywords: membrane distillation, high salinity, energy efficiency, system size, optimal membrane thickness * Corresponding author: lienhard@mit.

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Section: Context: Desalination Up To High Salinitymentioning

confidence: 99%

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

et al. 2018

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“…Permeate samples were taken every 50 cm 3 (16.67% of permeate recovery) until 50% permeate recovery was reached. Concentrations of the most important ions, Cl -, SO 4 2-, Na + , Ca 2+ and Mg 2+ , were determined using an ion chromatograph. Table 2 shows the obtained rejection coefficients for individual ions depending on the permeate recovery.…”

Section: Resultsmentioning

confidence: 99%

“…Saturated brine (a sodium chloride solution of concentration above 300 g/dm 3 ) is an important resource in the chemical industry. It is usually obtained by leaching underground salt deposits or by concentration of the saline waters (seawater, water from salt lakes and mine brines) with direct thermal methods or thermal methods preceded with membrane concentration [1][2][3][4][5][6][7]. Saline water is increasingly often desalinated and concentrated with membrane methods: pressure-driven membrane processes (mainly reverse osmosis, RO) and electromembrane methods (electrodialysis, ED; electrodialysis reversal, EDR) [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Energy consumption in RO-NF system can be decreased by 2%-12% compared with conventional multistage RO (MSRO) and water recovery can be increased from 50% (in MSRO) to 65%-85% [17,27,28]. Typical NF membranes are characterised by high rejection coefficients of multivalent ions (over 90% for SO 4 2-) and low rejection coefficients of monovalent ions, for example, Na + , Cl -(less than 60%) [29][30][31]. The NF permeate has a significant salinity compared with typical RO permeate; because of this, the operating pressure in NF can be much lower than in RO for the same feed: it is not the feed/retentate osmotic pressure (assuming that the RO permeate concentration value is close to zero) that should be overcome, but the difference in osmotic pressure of NF feed/retentate and NF permeate [32][33][34].…”

Section: Introductionmentioning

confidence: 99%

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Concentration of mine saline water in high-efficiency hybrid RO–NF system

Laskowska¹,

Turek²,

Mitko³

et al. 2018

Desalination and Water Treatment

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a b s t r a c tTo obtain higher concentration of sodium chloride than in reverse osmosis (RO), the hybrid RO-nanofiltration (NF) system was applied. The use of RO retentate pressure as a driving force in NF decreased the energy consumption in the brine concentration process and increased RO permeate recovery. In such a hybrid system, NF could be regarded as an alternative method of energy recovery. Five NF membranes were tested on the synthetic sodium chloride solution, conducted at 40 bar, with highest rejection coefficients 31.3%. Selected membranes were tested at the higher pressure (50, 55 and 60 bar) on the synthetic sodium chloride solution and on the coal-mine brine RO retentate (60 bar). Based on the obtained results, energy consumption in RO-NF-vapour compression (VC) system was estimated and compared with the RO-VC system. The energy consumption in the RO-NF hybrid system with VC (123.3 kWh/m 3 of brine with 290 g/dm 3 NaCl) was lower than in the currently used RO-VC system (213.2 kWh/m 3 of brine with 290 g/dm 3 NaCl without energy recovery and 204.6 kWh/m 3 of brine with 290 g/dm 3 NaCl with energy recovery).

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“…SWRO is the preferred technology due to low energy cost for producing one cubic meter of clean water (2-4 kw h m −3 ) when compared to thermally driven processes such as MD, multistage flashing, or multi-effect distillation where energy costs are twice as for SWRO (3)(4)(5).5 kw h m −3 ) for creating a phase change in water to drive separations 2,8 . However, SWRO can only process seawater with NaCl content between 3 and 4 wt.% and generates large amounts of brine solution (NaCl content >5 wt.%) that are difficult to treat 9 . Meanwhile, the use of hydrophobic carbonaceous membranes with water flux reaching 179 kg m −2 h −1 in MD can inhibit brine generation 3 , but such membranes are susceptible to fouling, affecting separation performance stability 6,10-12 .…”

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confidence: 99%

Tailoring the molecular structure of crosslinked polymers for pervaporation desalination

et al. 2020

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Polymer crosslinking imbues chemical stability to thin films at the expense of lower molecular transportation rates. Here in this work we deployed molecular dynamics simulations to optimise the selection of crosslinking compounds that overcome this trade-off relationship. We validated these simulations using a series of experiments and exploited this finding to underpin the development of a pervaporation (PV) desalination thin-film composite membrane with water fluxes reaching 234.9 ± 8.1 kg m −2 h −1 and salt rejection of 99.7 ± 0.2 %, outperforming existing membranes for pervaporation and membrane distillation. Key to achieving this state-of-the-art desalination performance is the spray coating of 0.73 μm thick crosslinked dense, hydrophilic polymers on to electrospun nanofiber mats. The desalination performances of our polymer nanocomposites are harnessed here in this work to produce freshwater from brackish water, seawater and brine solutions, addressing the key environmental issue of freshwater scarcity.

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Water recovery from brines and salt‐saturated solutions: operability and thermodynamic efficiency considerations for desalination technologies

Abstract: BACKGROUND-When water is recovered from a saline source, a brine concentrate stream is produced. Management of the brine stream can be problematic, particularly in inland regions. An alternative to brine disposal is recovery of water and possibly salts from the concentrate.

Cited by 34 publications

References 46 publications

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

Concentration of mine saline water in high-efficiency hybrid RO–NF system

Tailoring the molecular structure of crosslinked polymers for pervaporation desalination

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