Desalination Brine Research Articles

Facultative hybrid RO-PRO concept to improve economic performance of PRO: Feasibility and maximizing efficiency

A facultative hybrid reverse osmosis (RO) – pressure retarded osmosis (PRO) system can switch its operation between i) RO mode, where high quality water is produced from waste-water treatment plant effluent and ii) PRO mode, where the salinity difference between seawater desalination brine and wastewater is converted to energy. This system takes advantage of fluctuating energy pricing, by consuming low cost energy to produce water and producing high value energy.The system was modeled by a local concentration polarization and solution diffusion model, considering several geometries. The system was optimized and for different ratios of the economic value of electricity vs water, to find process settings and switch points. A necessary condition for the feasibility of the facultative hybrid RO-PRO concept is that the permeate value satisfies: i) low enough, to justify electricity production and ii) high enough, to justify water production. With a maximum energy price of 0.25 USD/kWh, the first condition translates into <0.10–0.17 USD/m3 (ALFS) or <0.20–0.28 USD/m3 (ALDS). The facultative hybrid RO-PRO concept is only feasible as improvement to a PRO system, where there is a limited demand for purified WWTP-effluent. It is expected that it is usually preferred to produce purified WWTP-effluent.

Pressure-retarded membrane distillation for simultaneous hypersaline brine desalination and low-grade heat harvesting

Membrane distillation (MD), an emerging pre-concentration technology for zero liquid discharge to manage industrial wastewater, has become increasingly attractive when the low-grade waste heat is utilized as its driving force. Pressure-retarded membrane distillation (PRMD) – a derivative of MD by applying a hydraulic pressure lower than the membrane liquid entry pressure at the cold permeate side – has the potential to further recover the low-grade heat in terms of electricity, which is an added benefit for the use of conventional MD. Here, we for the first time experimentally evaluated the feasibility of using PRMD for simultaneous desalination of hypersaline water and harvesting of low-grade heat and explored the mechanisms governing the experimental PRMD performance. Using a commercial membrane, NaCl solution at the concentration as high as 4 M (233.76 g L−1) is desalinated with the salt rejection >99.9% and additional energy is generated in PRMD at the same time. We showed that the membrane operated with its active layer facing a cold solution orientation in PRMD exhibits better mechanical stability at higher applied pressures, which is essential for achieving higher power output. However, in contrast to the other orientation that is used in conventional membrane distillation (MD) processes, the coupled effects of internal temperature polarization (ITP) and internal concentration polarization (ICP) lower effective driving force and membrane permeability, which significantly compromises the water vapor flux and peak power density. These results indicate that unlike MD processes, controlling internal scaling and fouling are critical for PRMD and our findings can serve as useful guides for creating high-performance PRMD membranes in practical environmental applications.

Numerical Prediction of Background Buildup of Salinity Due to Desalination Brine Discharges into the Northern Arabian Gulf

Brine discharges from desalination plants into low-flushing water bodies are challenging from the point of view of dilution, because of the possibility of background buildup effects that decrease the overall achievable dilution. To illustrate the background buildup effect, this paper uses the Arabian (Persian) Gulf, a shallow, reverse tidal estuary with only one outlet available for exchange flow. While desalination does not significantly affect the long-term average Gulf-wide salinity, due to the mitigating effect of the Indian Ocean Surface Water inflow, its resulting elevated salinities, as well as elevated concentrations of possible contaminants (such as heavy metals and organophosphates), can affect marine environments on a local and regional scale. To analyze the potential effect of background salinity buildup on dilutions achievable from discharge locations in the northern Gulf, a 3-dimensional hydrodynamic model (Delft3D) was used to simulate brine discharges from a single hypothetical source location along the Kuwaiti shoreline, about 900 km from the Strait of Hormuz. Using nested grids with a horizontal resolution, comparable to a local tidal excursion (250 m), far field dilutions of about 28 were computed for this discharge location. With this far field dilution, to achieve a total dilution of 20, the near field dilution (achievable using a submerged diffuser) would need to be increased to approximately 70. Conversely, the background build-up means that a near field dilution of 20 yields a total dilution of only about 12.

Process simulation and techno‐economic assessment of a zero liquid discharge/multi‐effect desalination/thermal vapor compression (ZLD/MED/TVC) system

Brine from desalination plants is an upcoming environmental threat to aquatic ecosystems. Multi-effect distillation with thermal vapor compression (MED-TVC) is proposed to treat desalination brine solutions of more than 70 000 mg/L of total dissolved solids (TDS). To achieve this, an integrated techno-economic model consisting of three submodels (scaling prediction, mathematical, and economic) is developed and a techno-economic assessment of a 10 m3/d MED-TVC system is presented under two different scenarios. In this respect, various sensitivity analyses were performed, revealing that the 4-effect MED-TVC system operating at 120°C feed steam presents the lowest freshwater cost (US$3.00/m3) and the lowest payback period (3.04 years) under the first scenario, whereas the 2-effect MED-TVC system operating at 120°C feed steam presents the lowest freshwater cost (US$1.69/m3) and the lowest payback period (1.71 years) under the second scenario of waste heat utilization. Exergy analysis for these optimal systems revealed that the exergy efficiency of the optimal system in the second scenario (4.36%) is higher than in the first scenario (4.21%). For both optimal systems, the exergy destruction in the TVC unit and in the effects accounts for more than 79% of the total exergy destruction. Moreover, it was found that thermal energy costs contribute significantly to the costs and affect the design procedure. Scaling up the optimal systems for freshwater production by more than 190 m3/d, freshwater cost becomes constant and can be reduced by up to 50% with waste heat integration. Considering the high quality of the freshwater produced, MED-TVC process can be profitable due to the revenue from the sale of the freshwater. Overall, the results suggest that the MED-TVC process for brine treatment is economically feasible.

Water Splitting in Brine: Engineering Electrolytes for Active, Stable, and Tunable Photoelectrochemical Cells

Solar-driven water splitting is a promising source of renewable energy, but faces several obstacles to widespread implementation, including photoelectrocatalyst activity, stability, and control. While current remedies focus on improving catalysts themselves (e.g., fabricating protective layers, modifying surfaces for higher activity), engineering electrolyte remains an underutilized strategy for tuning properties of photoelectrochemical cells (PECs). The goal of this project is to leverage aqueous chemistry to increase activity, stability, and control of photoelectrocatalysis. We demonstrate that saline waters increase activity (as cathodic H2 and anodic O2 production) through increased conductivity, and employ varying concentrations of NaCl electrolyte. To increase stability, we add aqueous buffer species such as carbonate, acetate, and ammonia to resist extreme pH changes that can degrade electrodes. We investigate tunability of PEC performance by changing electrolyte pH, organic content, and silica concentrations. Ultimately, we investigate mechanistic impacts of aqueous species in a TiO2/MoS2 PEC (standard photoelectrodes) through experiments with synthetic electrolytes of controlled composition; we also aim to establish proof-of-concept for photoelectrocatalytic energy production in desalination brines, an underutilized waste stream.

OMSD – An open membrane system design tool

A tool for design and performance analyses of filtration systems is presented. The tool evaluates the filtration rate and its associated power consumption of complex filtration systems, based on the system design, feed water characteristics, membrane characteristics and operating conditions. It is based on a modular concept, through which system elements, such as filtration modules or pumps, are assembled to build a virtual model of a filtration system. The system performance is based on its operating expenses, evaluated from the filtration rate, the filtrate solute concentration and the power consumption of the pumps and pre-treatment. The system analysis tool is applied to two case studies on the desalination of brackish water and brine. These studies compare various system configurations and operating conditions, based on their energy-efficiency. Based on the findings, general design principles are derived for brackish water and brine desalination. The tool presented here poses the first development stage in the development of an open, versatile and intuitive system design tool. Its open implementation allows for subsequent development contributions of the scientific community. The advantages over existing system tools are its transparency, its free extendibility, and the freedom to implement arbitrary filtration modules, without restrictions to commercial products.

Optimal synthesis of negative emissions polygeneration systems with desalination

Treatment of reverse osmosis desalination (ROD) brine has recently been suggested as a means to achieve negative greenhouse gas emissions via indirect ocean capture (IOC) of carbon dioxide. In this paper, a novel scheme that integrates the ROD/IOC process with combined cooling, heating, and power (CCHP) generation is proposed as a new negative emissions polygeneration system (NEPS). A mixed integer linear programming (MILP) model is then developed for the optimal synthesis and operation of such a system. The model uses a multi-period formulation to account for hourly variations in product demand and electricity price. The polygeneration system takes advantage of the flexible operation of the ROD/IOC process to operate as a Power-to-X (PtX) system, without the need for direct electricity storage in batteries. An illustrative case study is solved to demonstrate the model, and sensitivity analysis is performed to assess the effects of techno-economic uncertainties on system performance.

Field validation of self-regenerating reversible ion exchange-membrane (RIX-M) process to prevent sulfate and silica fouling

Desalination of brackish water and municipal wastewater will be integral to water resource resiliency during uncertain climate conditions. Higher efficiency and higher recovery than conventional desalination is achievable if biofouling and inorganic scaling can be avoided on membranes or heating surfaces. Temporary hardness is well addressed through acid and antiscalant dosing, but permanent sulfate hardness lacks selective removal techniques that do not require external chemicals or produce large volumes of sludge. Self-regenerating reversible ion exchange-membrane (RIX-M) processes have been proposed using a tunable anion exchange blend to remove silica and sulfate selectively from influent water with efficient regeneration via brine reject. A 2.5GPM RIX-M process was tested at the US Bureau of Reclamation (USBR) Brackish Groundwater National Desalination Research Facility (BGNDRF, Alamogordo, NM). High sulfate-containing brackish groundwater was desalinated at high recovery (80%) without membrane fouling through selective sulfate removal and regeneration via desalination brine reject, without external chemical addition. Ten treatment-regeneration cycles were performed without degradation in system performance. High efficiency silica removal from complex groundwater backgrounds at BGNDRF was also achieved across varying water chemistries. RIX-M offers a new pre-treatment opportunity to protect RO membranes from sulfate and silica fouling without dosing anti-scalants, while attaining high recovery.

Desalination brine disposal methods and treatment technologies - A review.

Brine, also known as concentrate, is the by-product of the desalination process that has an adverse impact on the environment due to its high salinity. Hence, viable and cost-effective brine management systems are needed to reduce environmental pollution. Currently, various disposal methods have been practiced, including surface water discharge, sewer discharge, deep-well injection, evaporation ponds and land application. However, these brine disposal methods are unsustainable and restricted by high capital costs and non-universal application. Nowadays, brine treatment is considered one of the most promising alternatives to brine disposal, since treatment results in the reduction of environmental pollution, minimization of waste volume and production of freshwater with high recovery. This review article evaluates current practices in brine management, including disposal methods and treatment technologies. Based upon the side-by-side comparison of technologies, a brine treatment technology framework is introduced to outline the Zero Liquid Discharge (ZLD) approach through high freshwater recovery and wastewater volume minimization. Furthermore, an overview of brine characteristics and its sources, as well as its negative impact on the environment is discussed. Finally, the paper highlights future research areas for brine treatment technologies aiming to enhance the effectiveness and viability of desalination.

Sequential carbonate mineralization of desalination brine for CO2 emission reduction

Desalination brine is a potential source for CO2 mineralization aimed at reducing CO2 emissions, because the concentration of Ca and Mg in brine is almost twice that of ordinary seawater. However, the previously achieved conversion ratio of CO2 to carbonate minerals is too low for commercial application, as Ca and Mg compete and interfere with each other during precipitation. In this study, we tested the separate and sequential mineralization of Ca and Mg in brine, enhancing the CO2 conversion ratio to 57% from 12%. We also tested the use of 15% CO2 gas (the typical concentration of actual combustion gas), and it was observed that 69% of injected CO2 was precipitated as Ca and Mg carbonate minerals and 99% of Ca and 69% of Mg in the initial brine were precipitated. In addition, the volume of NaOH solution required was reduced by 76%. This revised method is more material- and reagent-efficient which would likely have lower operation costs; moreover, as no further additives are required, environmental impact of brine release is also likely to be reduced. The findings of this study can help address environmental problems caused by large seawater desalination plants and thermal power plants.

Lithium recovery from desalination brines using specific ion-exchange resins

This study evaluated the possibility of recovering lithium from brines by ion-exchange procedures. Three commercial ion-exchange resins were studied: K2629, TP207 and TP208.Different tests have been carried out with artificial solutions and real brines. In addition, tests were carried out for Li elution, regeneration of the resins and reuse of the regenerated resins.Sorption kinetics of lithium retention onto the three resins were studied and experimental data fit to the pseudo-second order kinetics model. Equilibrium sorption data were analysed by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevic approaches. Langmuir isotherm model best described the process. The order of retention capacity of the amendments was TP207 > K2629 > TP208.Recovering Li from brines was possible with ion exchange resins. In solutions containing only Li, the three resins studied had high retention yields (>95%). The presence of other ions in solution negatively affects the behavior of the three resins studied.Regarding desorption, yields obtained ranged 73.8% - 89.8%, reaching the highest (>80%) using 4 M HCl as eluting solution. Regenerated resins showed similar yields to those obtained when the resin is used for the first time.

Effect of oscillating temperature and crystallization on graphene oxide composite pervaporation membrane for inland brine desalination

Membrane distillation (MD) for desalination experienced technical challenges when treating concentrated inland brine with high salinity under industrially-relevant oscillating temperature condition or solar desalination. In this study, we fabricated a composite membrane using graphene oxide (GO) and used it in a pervaporation (PV) process to tackle the issues encountered in the MD processes. The resultant GO composite membranes demonstrated fast water vapor transport through nano-channels between the GO interlayers. In addition, the smoother and negatively charged surface offered by the GO layer hindered the undesired crystal deposition on the membrane surface, and therefore giving a substantially improved performance than the MD process when operated under oscillating temperature. More importantly, the presence of divalent cations in inland brine led to a naturally-occurring crosslinking between the GO nanosheets that offered molecular sieving functionality to the GO layer, preventing the transport of salt ions, as well as GO swelling and therefore providing exceptional performance sustainability, especially under oscillating temperature condition. Interestingly, it was found that GO composite membrane in a PV process for desalination offered greater overall water productivity when operated under the oscillating temperature compared to the constant temperature. These GO composite membranes also demonstrated good performance stability after chemical cleaning and when exposed to minor contaminants found in inland brine such as humic acid.

Surface-Induced Silica Scaling during Brackish Water Desalination: The Role of Surface Charge and Specific Chemical Groups.

Silica scaling of membranes used in reverse osmosis desalination processes is a severe problem, especially during the desalination of brackish groundwater due to high silica concentrations. This problem limits the water supply in inland arid and semiarid regions. Here, we investigated the influence of surface-exposed organic functional groups on silica precipitation and scaling. A test solution simulating the mineral content of brackish groundwater desalination brine at 75% recovery was used. The mass and chemical composition of the precipitated silica was monitored using a quartz crystal microbalance, X-ray photoelectron spectroscopy, and infrared spectroscopy, showing that surfaces with positively charged groups induced rapid silica precipitation, and the rate of silica precipitation followed the order -NH2 ∼ -N+(CH3)3 > -NH2/-COOH > -H2PO3 ∼ -OH > -COOH > -CH3. Force vs distance AFM measurements showed that the adhesion energy between a silica colloid glued to AFM cantilever and the studied surfaces increased as the surface charge changed from negative to positive. Thus, for the first time direct measurements of molecular forces and specific chemical groups that govern silica scaling during brackish water desalination is reported here. The influence of the different functional groups and the effect of the surface charge on silica precipitation that were found here can be used to design membranes that resist silica scaling in membrane-based desalination processes.

Feasibility Study of Net CO2 Sequestration Using Seawater Desalination Brine with Profitable Polyproduction of Commodities

We present a profitable pathway from desalination waste brines to negative CO2 emissions. The method, termed ‘brine to bricks’ (BtB), mineralizes CO2 as nesquehonite (MgCO3･3H2O) using the Mg content of brines. Fresh water, gypsum (CaSO4･2H2O), halite (NaCl), mirabilite (Na2SO4･10H2O), sylvite (KCl), and hydrochloric acid are concurrently produced. To prevent ‘carbon leakage’, BtB does not rely on external chemicals, fossil fuel-derived heat and power, or captured CO2. BtB selectively precipitates CaSO4･2H2O, NaCl, and Na2SO4･10H2O by evaporative concentration and temperature-control. The remaining Na+ and K+ ions are separated as NaCl and KCl from the magnesium chloride slurry by hydrochloric acid-based precipitation. Super-azeotropic hydrochloric acid is regenerated from the slurry using a novel method: low hydration magnesium chloride addition. Purified magnesium chloride is decomposed to amorphous MgO prior to reaction with ambient CO2. The current NET potential of BtB, including the CO2 emissions from desalination, is 136 MtCO2/y. In the current market, BtB can operate at a profitability up to $266/t-CO2, dependent primarily on the availability of waste heat and the local performance of renewable energy. Based on current desalination adoption projections, BtB could remove 0.350-1.784 GtCO2/y by 2050 while providing substantial increases in fresh water, construction materials, and chemicals that are of use to other negative emission technologies.

Development and performance assessment of a new integrated solar, wind, and osmotic power system for multigeneration, based on thermodynamic principles

This study analyzes a new renewable energy-based multigeneration system, in which the energy sources are efficiently utilized to generate several useful commodities such as hydrogen, oxygen, desalted water, and refrigeration along with electricity. Osmotic power from desalination brine solution is harvested to contribute to the electricity generation and to reduce the environmental impact of brine. The system units are concentrated photovoltaics/thermal (CPVT), wind turbines, thermal energy storage (TES), hydrogen electrolyzer, hydrogen fuel cell, multistage flash (MSF) distillation, vapor compression refrigeration (VCR) cycle, and pressure retarded osmosis (PRO). The energetic and exergetic performance of the overall system, as well as the system units, are calculated based on the first and second law of thermodynamics. Further, a comprehensive parametric study is conducted to investigate the effect of varying environmental and operational conditions, and the input parameters on the production rate, exergy destruction rate and efficiencies. For maintaining the high efficiency of CPV operation, the heat generated on photovoltaic (PV) cells is dissipated by an effective cooling system. This heat is then stored in the TES to be further utilized in desalination. The TES is used for eliminating energy fluctuations in the system and for a continuous operation by storing the energy for the time, when energy from the sun is not available. The electricity from CPV and wind power is used in the VCR cycle and hydrogen electrolysis. The fuel cell can be operated during the time of peak electricity demand. After performing thermodynamic analysis over the system, the overall energy and exergy efficiencies are determined as 73.3% and 30.6%, respectively. The exergy destruction rates of the components are specified. In brief, generation of multiple commodities is assured based on a clean operation by a novel integration of multiple clean energy sources in one system.

Techno-economic analysis of ion concentration polarization desalination for high salinity desalination applications

A techno-economic analysis is used to evaluate the economic feasibility of ion concentration polarization (ICP) desalination for seawater desalination and brine management. An empirical optimization model based on a limited set of experimental data, which was obtained from a lab-scale ICP desalination prototype, was established to calculate the required energy and membrane area for a given set of operating parameters. By calculating operating and capital expenses in various feed and product cases, the optimal levelized cost of water is determined over a range of feed salinities, mostly above seawater salinity (35 g/kg). Through these analyses, we study the economic feasibility of three applications: 1) partial desalination of brine discharge by ICP (feed varied from 35 to 75 g/kg) to common seawater RO feed level (35 g/kg) in a hybrid ICP-RO system; 2) the concentration of seawater desalination brine for salt production, and 3) partial desalination of oilfield wastewater. The economic feasibility of ICP desalination processes has been evaluated and the rough cost of treatment has been generated for several relevant applications. The approach taken in this work could be employed for other new and existing desalination processes, where a priori process modeling and optimization is scientifically and/or numerically challenging.

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges.

The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high-salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

AbstractThe rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high‐salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.

Effects of desalination brine and seawater with the same elevated salinity on growth, physiology and seedling development of the seagrass Posidonia australis

Desalination has the potential to provide an important source of potable water to growing coastal populations but it also produces highly saline brines with chemical additives, posing a possible threat to benthic marine communities. The effects of brine (0%, 50%, 100%) were compared to seawater treatments with the same salinity (37, 46, 54 psu) for seagrass (Posidonia australis) in mesocosms over 2 weeks. There were significant differences between brine and salinity treatments for photosynthesis, water relations and growth. Germinating seedlings of P. australis were also tested in brine treatments (0%, 25%, 50%, 100%) over 7 weeks followed by 2.5 weeks recovery in seawater. Growth was severely inhibited only in 100% brine. These experiments demonstrated that brine increased the speed and symptoms of stress in adult plants compared to treatments with the same salinity, whereas seedlings tolerated far longer brine exposure, and so could potentially contribute to seagrass recovery through recruitment.

Hydration, Strength, and Shrinkage of Cementitious Materials Mixed with Simulated Desalination Brine

Abstract The process of desalination results in the production of a hypersaline waste by-product known as reject brine. In some locations, this reject brine is dumped back into the ocean, which has potentially detrimental effects on water quality and marine life. This study was carried out to investigate whether this brine could potentially be used to manufacture cementitious materials. The effects of different concentrations of simulated reject brine on hydration kinetics, compressive strength, and drying shrinkage of cement paste and mortar were investigated. Cement paste and mortars were prepared using a water-to-cement ratio of 0.45 and were mixed with simulated reject brine, tap water, and diluted reject brine (an equal mass mixture of reject brine and tap water). The results show that the reject brine causes an acceleration of early cement hydration; however, this effect is negligible at later ages. Mixtures containing reject brine have higher compressive strength at early ages, although this difference is reduced at 91 d. The reject brine causes a drastic increase in the drying shrinkage. The difference between the results obtained using reject brine and diluted reject brine were generally insignificant, which suggests that the effects of solution composition on the observed properties were not strong when solution concentrations were greater than a threshold value. Although these results are preliminary and further feasibility studies, including research on concrete durability, are required, the results suggest that reject brine may be used to make unreinforced concrete or concrete reinforced with noncorrosive materials.