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Solar interfacial water evaporation is an environmentally friendly and potential approach to producing fresh water. Herein, a PAN/CNTs-foam (PCF) evaporator with high porosity, hierarchical pore structure, and excellent solar absorption was successfully prepared by the vacuum casting method. The PCF prepared with a CNTs content of 17 % and NaCl particle size of 150–300 μm possessed an evaporation rate of 2.04 kg m−2 h−1 for pure water under 1 sun illumination. The PCF-2 showed a maximum evaporation rate of 5.60 kg m−2 h−1 for real seawater in outdoor experiments, and the quality of the produced clean water was also demonstrated. The purification ability of PCF for organic dyes further confirmed the potential usage in wastewater treatment. Particularly, the PCF-2 exhibited efficient and stable desalination performance for hypersaline water even in 25 wt% simulated brine due to the hierarchical interconnected channels. Our work offers a robust method for the construction of a 3D foam evaporator with hierarchical interconnected channels for efficient and sustainable hypersaline water desalination. [Display omitted] • A 3D PCF evaporator with hierarchical pore structure and controllable pore size was successfully prepared by the vacuum casting method. • The prepared PCF-2 evaporator showed a high evaporation rate and evaporation efficiency. • The PCF-2 evaporator possesses excellent salt resistance and can be for the treatment of hypersaline water. [ABSTRACT FROM AUTHOR]

The treatment and disposal of hypersaline produced water remains a challenge, particularly for oil and gas producers in the Permian basin where production wells generate significant amounts of wastewater, and the traditional method of injecting wastewater into disposal wells is coming under increasing scrutiny. Here we investigate the viability of using solar energy to power a multi-stage, surface heated, vacuum membrane distillation (SHVMD) with energy recovery to treat hypersaline produced wastewater from Midland, Texas. Membrane distillation is a process that can desalinate waters with high total dissolved solids concentration, and when incorporated into a system with surface heating and energy recovery can achieve high water recovery rates. Model results show that a 6-stage SHVMD system with a 54.4 % water recovery rate and a gained output ratio (GOR) of 3.28 has the potential to be economically viable when used to treat hypersaline produced water in the Permian basin. Assuming energy costs of $0.03/kWh thermal and $0.12kWh electric , we estimate a project net present value (NPV) of $225,525 and an internal rate of return (IRR) of 13.5 % when an air cooled condensor is used to cool the distillate and a NPV of $570,791 and IRR of 24.52 % when a liquid coooling source is available. This work presents a comprehensive economic assessment of utilizing a surface-heated membrane distillation system with heat recovery to treat hypersaline produced well water. • An economic analysis of surface-heated membrane distillation process for the treatment of hypersaline brine was performed • Under certain conditions, the process is economically viable compared to deep-well injection • Process economics are sensitive to the availability of liquid cooling, sunlight, and the cost of solar-thermal energy [ABSTRACT FROM AUTHOR]

Freezing desalination has gained interest due to its potential to reduce energy use. The freezing process faces challenges that limit its wide use. Washing product ice causes a large mass loss. Most freezing processes involve crushing to generate the appropriate ice form, limiting large-scale production. A vacuum pump and pressing piston are experimentally utilized to collect brine during melting to avoid washing and crushing ice. Five brine separation processes are needed to produce 2 %-salinity water. The studies used salinity-varying feed water. From the results, utilizing a vacuum pump and piston for brine separation during melting and a relatively small number of separation steps has considerably enhanced the quality of the produced water without causing significant mass loss. It is observed that 1000 ml of 15,000 ppm feed water produces freshwater with salinity and volume equal to 114 ppm and 185 ml, respectively. Results indicate that when the COP varied from 4 to 6, the system performance ratio increased from 31.74 to 47.62 and 7.94 to 11.90, with a recovery ratio equal to 0.9 and 0.6, respectively. Compared to previously described freeze desalination, MSF, MED, and MD desalination systems, the specific energy consumption increases by 71.5 %, 66.4 %, 54.5 %, and 36.1 %. • Crushing and washing free, freezing desalination technology • A technique that involves brine extraction by vacuum • Experimental investigation at different feed salinities • System performance ratio ranged from 31.74 to 47.62. [ABSTRACT FROM AUTHOR]

The lithium extraction from emerging unconventional oil and gas (UOG) field brine by β -diketone synergic system was established and systematically studied for the first time. A synergistic system consisting of dibenzoylmethane (DBM) and trioctylphosphine oxide (TOPO) was screened for lithium extraction through high-precise DFT calculation, and the synergistic effects were revealed by FT-IR analysis. A state-of-the-art Li+-Mg2+-Ca2+ co-extraction and Li+ selective stripping (CESS) process was proposed to achieve high lithium recovery efficiency. The effects of saponification, phase ratio, extractant composition and stripping acidity on extraction efficiency were systemically studied using real UOG field brine. After three-stage countercurrent extraction, the lithium extraction efficiency reached 98.1 % with the DBM concentration of 0.25 mol/L, TOPO concentration of 0.25 mol/L, and saponification of 70 %. After selective stripping and scrubbing with gradient HCl concentrations, Li+ was further separated from Na+, Mg2+ and Ca2+. The mass ratio of Mg2+/Li+ was reduced by 49.7 times, Na+/Li+ was reduced by 102.4 times. This work bridged the gap in the solvent extraction of lithium resources from UOG field brines and provided ideas for UOG field resource exploit and comprehensive utilization. [Display omitted] • Solvent extraction of lithium from actual unconventional oil and gas field brine was studied for the first time. • A state-of-the-art Li+-Mg2+-Ca2+ co-extraction and Li+ selective stripping process was established. • A synergistic system consisting of DBM and TOPO was selected for lithium extraction through DFT calculation. • 98.1 % of lithium was extracted after three-stage countercurrent extraction. [ABSTRACT FROM AUTHOR]

Increasing disposal costs and environmental concerns have encouraged desalination projects in the Permian basin to cut down produced water (PW) volumes and improve the handling. This study aims to demonstrate performance of membrane-distillation (MD) for desalinating high-salinity PW. Prior to MD, electrocoagulation (EC) and microfiltration (MF) are used as primary and secondary pretreatments, respectively. These pretreatment steps are necessary to remove constituents such as suspended solids, oil, and grease. The integrated EC-MF process was followed by vacuum MD (VMD) to recover water and concentrate the brine stream. To improve latent heat recovery, vapor compression is integrated into the vacuum membrane distillation (VMD). Our EC-MF-VMD PW treatment process can treat 1000 L of PW per day, with water recoveries in the range of 30–70 %. Suspended solids and turbidity removal of 90 % and total organic carbon (TOC) removal of 60 % were achieved with EC-MF pretreatments, which effectively mitigated PW fouling potential. A custom-designed plate-and-frame VMD module was established which enabled unparalleled service flexibility to change membrane replacement and active area. Results from our systematic evaluation revealed that the flux of the commercial membranes in our VMD module varied from 5 to 66 Lm−2 h−1. The intensified VMD performance achieved by vapor compression led to remarkable improvement in energy efficiency in terms of gained output ratio (GOR = 2.7) and energy consumption per unit of water production (248 kWh m−3). This study demonstrates the capability of the MD process for PW treatment, revealing the reasonable potential for PW reuse and recycling. Although this process might be of interest for unique applications that justifies the cost, further improvements in energy consumption are required to make this technology feasible for commercialized desalination of oilfield produced waters. • MD prototype demonstrated for treating hypersaline produced water. • Hybridizing EC and MF resulted in superior pretreatment performance. • Custom-designed plate-and-frame MD module exhibited fluxes up to 66 Lm−2 h−1. • Long-term operation demonstrated excellent water recovery and GOR > 2.7. [ABSTRACT FROM AUTHOR]

A novel multipurpose seawater desalination process is presented that integrates a Lithium Bromide (LiBr) absorption chiller, humidification-dehumidification (HDH), multi-effect evaporator, and mechanical vapor recompression (MVR) to improve the energy effectiveness of conventional desalination processes. The proposed process uses the LiBr absorption chiller cycle to preheat the seawater prior to the steam generation in the multi-effect evaporators while the MVR system activates the LiBr cycle. The integration of HDH further allows to recover the excess water in the process stream and concentrates the brine effluent for zero liquid discharge processing. A stand-alone HDH desalination is comparatively studied with the integrated system to quantify their respective performances over several metrics. Technoeconomic analysis is also performed to assess the economic feasibility and a sensitivity analysis is carried out to observe the effects of changing process variables on the overall performance of these systems. The results show that the proposed process design achieves several times higher gain-output ratio compared to a conventional HDH system of equal capacity, with a levelized water production cost of $ 8.4 / m 3 and 6 kW of cooling capacity that can be used for air conditioning. [Display omitted] • A multipurpose desalination plant is designed and analyzed. • The LiBr absorption cycle is activated by mechanical vapor recompression. • The levelized cost of produced water is $8.4/m3 with a cooling capacity of 6 kW. • NaCl composition in the brine effluent is 21 wt%. • A recovery ratio of 81 % is achieved in the proposed process. [ABSTRACT FROM AUTHOR]

Room-temperature ionic liquids (RTILs) have been promoted as "green" chemicals that can be used as alternatives to conventional volatile organic solvents. In addition to low volatilities, hydrophobicity for organic liquids and hydrophilicity for ions in RTILs lead to a wide spectrum of applications. ILs have recently been considered as alternative solvents to carboxylic acids and amines used for solvent extraction desalination (SED). RTILs are used in pairs of cations and anions that can significantly influence SED potentials. This study aimed to find an optimal combination of cationic and anionic RTIL as a desalination solvent through theoretical, experimental, and computational approaches. SED potentials in terms of water absorption and salt rejection were investigated for ten pairs of RTILs using different combinations of imidazolium and phosphonium cations with various anions. SED potentials were highly dependent on the anion type, with Tf2N showing the most promising SED potential. Imidazolium based RTILs exhibited better SED performances than phosphonium based RTILs in experiments. [BMIM][Tf 2 N] was recommended as a candidate SED-IL material, showing a water absorption and salt rejection of 1.73 % and 93.7 %, respectively. Molecular dynamics (MDs) simulation was implemented in parallel in order to examine and analyze intermolecular interactions that led to particular experimental observations. [Display omitted] • Cation-anion RTIL combinations for solvent extraction desalination were investigated. • Solubility parameter (HSP) of RTIL pair was related to SED potentials. • Selection of anion IL was more important for SED. • Molecular interactions between ILs and water were simulated and analyzed through MD. • Experiments and MD simulation for RTIL-SED were well matched. [ABSTRACT FROM AUTHOR]

Thermodynamic data of multicomponent brines are needed to properly treat brines from oil/gas and CO 2 sequestration operations. Joule-heating treatment of hypersaline brine is a unique methodology that allows for direct heating of brines without the need of external heating, potentially simplifying operation and reducing process footprint. The thermodynamic properties of multicomponent hypersaline brine (> 3.5 wt%) are unknown and limited to estimations based on single component brine data. Experimental data for multicomponent brines at elevated temperatures and pressures do not exist due to operating conditions above the pseudocritical point of pure water. This study combines experimental results for multicomponent brines using a Joule- heated desalinator at pressures of 230 to 280 bar and temperatures of 387 to 406 °C with thermodynamic models previously created for single component NaCl brines to identify the deviations resulting from the additional species. In addition, a comparison between an Aspen Plus® v9 simulation using the ELECTNRTL model with experimental results is provided. [ABSTRACT FROM AUTHOR]

Gravity-Driven Membrane (GDM) is considered an emerging seawater reverse osmosis desalination pretreatment. The objective of this study was to assess the GDM process performance under different operating conditions and to evaluate the impact of membrane biofilm on the produced water quantity and quality. Three lab-scale submerged GDM systems (UF 12h , UF 24h and MF 24h) were tested under different conditions of Hydraulic Retention Time (HRT) (12 h/24 h) and membrane pore size (Microfiltration/Ultrafiltration). The best water quality in terms of Assimilable Organic Carbon (AOC) was achieved with the longer HRT (24 h), where significant AOC was removed by the biofilm developed on the membrane. The next generation sequencing indicated that a longer HRT increased the abundance of Proteobacteria and Planctomycetes in the biofilm, which due to their biodegradation capability yielded to the highest AOC removal (~50–55 %). Furthermore, the use of microfiltration led to the highest water production (9.1 L/m2/h) due to larger membrane pore size, and a less dense biofilm. These findings indicate that employing a microfiltration membrane and 24 h HRT provides the best performance in terms of water quantity and AOC-removal. This study demonstrates that controlling GDM design and operation enabled manipulation of the biofilm proprieties yielding to high water production and high AOC-removal. [Display omitted] • GDM for SWRO pretreatment was tested under different HRT and membrane pore sizes. • GDM operating conditions impacted biofilm morphology and composition. • Permeate water quality improved by the GDM biofilm development. • Longer HRT led to higher Assimilable Organic Carbon (AOC) removal from the seawater. • AOC removal was enhanced by the abundance of specific bacteria in the biofilm. [ABSTRACT FROM AUTHOR]

Produced water is the largest volume byproduct stream in oil and gas production, and has an adverse environmental impact due to its complex composition and high disposal costs. Membrane fouling due to hydrocarbons limits purification of produced water by reverse osmosis (RO). A novel hybrid adsorption/ion exchange (IEX)/RO process is developed in which the adsorber removes dissolved hydrocarbons, IEX removes scale causing precursors, and RO desalinates the water. A part of the hydrocarbon free liquid from the adsorber is pressurized to 6.2 bar, heated to 160 °C and used to regenerate the adsorber, which resulted in an improvement in water recovery (to 86%), and translated into a predicted 22.8% decrease in costs amounting to US$ 27 million annual savings. The new high water recovery processes delineated in this work provide an array of novel options for removing hydrocarbons and desalination under different conditions. Experimental studies are needed to verify the assumptions made in this analysis. [ABSTRACT FROM AUTHOR]

Unconventional oil and gas production raises concerns regarding sustainable management of high salinity wastewaters generated in this process. Membrane distillation (MD) is a thermal desalination process capable of treating hypersaline brines such as produced water. The low single pass recovery in MD systems operated in a single stage requires a large recycle stream to achieve the desired recovery, resulting in high energy consumption and operating cost. Multistage configurations in continuous recirculation operation mode offer the potential to reduce the energy intensity of MD systems. However, rigorous analysis is needed to assess the performance of MD configurations when operating in multi-stage mode. We present an optimization-based comparison of economic and energetic performance for five configurations of MD (including DCMD, AGMD, PGMD, CGMD, and VMD) operating in multi-stage continuous recirculation mode. Our findings demonstrate that multistage operation reduces the treatment cost and energy intensity of all MD configurations compared to single stage MD, with the greatest benefit for VMD and PGMD. AGMD with five stages outperforms other configurations with 3.58 $/m3 feed treatment cost, followed by VMD, CGMD, DCMD, and PGMD with 3.8, 4.2, 5.4, and 9.06 $/m3 feed treatment costs corresponding to twelve, eight, eight, and sixteen stages, respectively. • Developed an optimization framework for comparing five multistage MD configurations. • Continuous recirculation mode is analyzed for produced water treatment. • Treatment cost and energy intensity are compared for the five MD configurations. • Multistage MD offers energy and economic benefits over single stage MD. • AGMD outperforms all other configurations with lowest treatment cost. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) is suitable for brackish water desalination due to its unique electro-demineralizing mechanism. However, the role of typical factors in pilot-scale ED desalination performance has not been illustrated systematically. In this study, a pilot-scale energy-efficient ED system was manufactured for the desalination of seawater nanofiltration permeate which could be considered as a typical brackish water, and its influencing mechanisms of typical factors were investigated in detail. The factors included ion exchange membrane (IEM) type, water recovery (WR), temperature, and feed concentration. The results show that the permselectivity of IEMs, which is related to the leakage of co-ions, played an important role in ED desalination performance. Furthermore, the salinity of produced water increased 3-fold times with the WR increasing from 53 % to 67 % due to the intensification of ionic back diffusion. Besides, the SEC increased 37.7 % with similar salt removal ratio when temperature increased from 7 to 29 °C, which is attributed to the changes of IEM structures and solution chemical properties. Finally, the fluctuation in the feed concentration had significant influence on produced water quality and SEC due to continuous operation mode. This study provides insights into, and guidance for, the large-scale BWED desalination process. [Display omitted] • Membrane permselectivity affected co-ion leakage and caused energy consumption increase. • Water recovery had a great impact on concentration polarization and produced water quality. • Temperature greatly influenced the reverse ion diffusion and made energy consumption increase. • BWED performance was closely related to feed concentration fluctuation. [ABSTRACT FROM AUTHOR]

Produced water management is one of the key challenges faced by the oil and gas industry globally. Specifically, the gas industry in Qatar is challenged to minimize the produced/process water (PPW) volumes injected into disposal wells to ensure long term sustainability of the reservoirs. This research evaluated a novel application of forward osmosis (FO) to reduce the volumes of PPW disposed of by deep well injection using brine from thermal desalination plants or seawater as draw solutions. In the case of brines, this process also provides some environmentally beneficial dilution before discharge. In order to verify the PPW volume reduction concept, bench-scale FO experiments were carried out using commercial flat sheet membranes. FO performance was evaluated using PPW with and without pretreatment and results confirm that pretreatment is key to the successful implementation of FO for the treatment of PPW. Experimental results indicate that FO is effective in achieving 50% volume reduction of pretreated PPW with stable flux of 12 LMH. Lab analyses show that the TOC in the diluted draw solution was below the detection limit indicating that the TOC from the feed did not appear in the draw solution and hence would not be discharged to the environment. [ABSTRACT FROM AUTHOR]

Produced water generated from oil and gas operations contains significant quantities of environmentally hazardous hydrocarbons, organic chemicals, and inorganic salts. Environmental regulations with impaired water disposal mandates produced water treatment and desalination. Industry standard desalination technologies are energy-intensive and mandate extensive produced water pre-treatment including removal of hydrocarbons constituents for efficient operations. This study investigates a novel process intensification approach integrating supercritical water oxidation (SCWO) unit operation with a supercritical water desalination (SCWD) process for energy efficient produced water treatment and desalination. The coupled SCWD-SCWO process is found to be very energy-efficient and cost effective than existing industry standard desalination technologies. For energy efficient operation, the heat generated from the SCWO of hydrocarbons present in the produced water is used for power generation using a high efficiency and low-cost re-heat Rankine cycle process. The cost of treating produced water with proposed SCWO-SCWD process is independent of the salt concentration. The proposed process has the potential to offer step-change improvements over conventional processes in both the efficiency and cost of produced water treatment: for example, a cost and energy saving of 70% and 100% is calculated for the treatment of produced water containing 250 g/l salt and 10.6 g/l hydrocarbon. [Display omitted] • Novel approach to produced water treatment • Net zero energy consumption, with 70% lower cost • Treatment cost independent of produced water salt concentration • Using organics energy to generate power and desalinate the feed [ABSTRACT FROM AUTHOR]

Indigenous microalgae consortia present in domestic wastewater, were acclimatized to three real produced water (PW) samples collected from different oil fields. PW, a byproduct of oil mining and extraction, is hypersaline and toxic. Therefore, progressive adaptation mechanism was applied for acclimatization in a steadily decreasing dilutions of PW. After acclimatization, algae consortia were used for biodesalination and treatment of PW. The acclimatization lag phase was longer when the dilutions were reduced. The predominant species present in the consortia were Chlorella. One PW sample (onshore with largest initial salinity) showed the earliest adaptation (13 days) at lowest dilution. Chloride and salinity removal efficiencies of 25% and 22% were achieved, respectively, along with significant decrease in total dissolved solids (TDS) and conductivity in the different samples. The same PW sample showed highest removal of chloride (25%, from initial 53 g/L to final 40 g/L) and COD (44%). Another PW sample showed highest removal of salinity (22%), electrical conductivity (9%), TDS (20%) and total organic carbon (26%), as well as highest increase in alkalinity (86%). Removal efficiencies were minimum in the last PW sample which also showed less adaptability to the same dilution ratio of other two PW samples. [Display omitted] • Acclimatized algae consortia used for desalination and treatment of three different produced water samples. • Progressive adaptation mechanism adopted for acclimatization in steadily decreasing dilutions of PW. • Raw hypersaline PW without pretreatment used with very minimal inputs of nutrients supplements • Significant removal efficiencies of chloride (25%) and salinity (22%) along with 44% COD removal were achieved. [ABSTRACT FROM AUTHOR]

In the existing nuclear power plants, almost 60 to 70% of produced heat in the reactor is released to the ambient through the condenser, which can be used as the feedwater of reverse osmosis (RO) desalination plants. Although increasing the temperature of RO feedwater improves the overall performance, the quality of produced water decreases. This difficulty can be solved by blending the high-quality water produced by thermal desalination plants (DPs) with RO products. However, supplying the required energy for driving the thermal DP needs to consume a huge amount of fossil fuel, which is contrary to net zero-emission goals. In this study, three different scenarios, based on the solar plant (SP) (scenario 1), small modular reactor (SMR) (scenario 2), and the hybrid SMR-SP (scenario 3) for supplying the required energy of DP have been suggested. According to the techno-economic evaluation conducted in this study, using the SMR as the auxiliary heat source of the SP in the third scenario can be considered as a promising technology, which is associated with several benefits. However, the average water cost in scenario 2 is 66 cent m 3 , which almost 8.5 and 5% is less than scenarios 1 and 3, respectively. • The effects of using the rejected water of NPP's condenser as the feedwater of the desalination plan • Developing three different schemes based on SMR-Solar cogeneration plant equipped with modular PCM storage system • Developing a new program based on the Fortran language to simulate various components of the schemes • A general techno-economic comparison of SMR-Solar cogeneration schemes for desalination [ABSTRACT FROM AUTHOR]

Produced water is the largest source of wastewater in the oil and gas industry. One of the approaches to manage excess produced water is to increase its reuse opportunities using desalination technologies such as reverse osmosis. This article presents an experimental study using high temperature reverse osmosis membranes to treat produced water in a relatively high temperature range. Synthetic water was prepared using the produced water formula containing 10,600 mg/L of Total Dissolved Solids (TDS) and 83 mg/L of boron. Different pH and temperature conditions were evaluated to simulate the field operation conditions. The selected membrane module demonstrated high boron rejection at the test condition of pH 11 in the temperature range of 25 °C–60 °C. More than 98% of boron rejection was achieved at the maximum testing temperature of 60 °C. The membrane software was calibrated with the lab test data. Further lab studies using field produced water at 55 °C showed consistent results for boron and TDS rejections. Calibrated membrane software was used to perform system-level design at various recovery rates; the projected water quality and pressures had good alignment with the lab test results. The consistent membrane performance in this study provides an opportunity to undertake future field study using the RO membranes to treat high temperature produced water. • Produced water desalination was evaluated using lab facilities on high temperature RO membrane. • Boron rejection data at combined high temperature and high pH conditions was reported for the first time. • Membrane software was calibrated using lab testing results and full system scale projection was performed. • Field produced water sample was collected and tested at raised system recovery rates of 40%–75%. [ABSTRACT FROM AUTHOR]

Thermal desalination technologies are required for minimal and zero liquid discharge (MLD/ZLD). However, conventional and emerging thermal desalination technologies, such as mechanical vapor compression (MVC) and membrane distillation (MD), are usually highly expensive to implement or/and energy intensive to operate. In this study, we develop a novel desalination technology by using a vapor-compression pump to assist membrane distillation (MD). Comparing the energy efficiencies of the novel heat-pump assisted MD (HPMD), MVC, and conventional MD under similar operating conditions, demonstrates that HPMD is an energy-efficient thermal desalination technology. Furthermore, through process modeling, we provide guidelines for HPMD system design and show that the HPMD can theoretically obtain low energy consumption (~10 kWh of electrical energy per cubic meter of produced fresh water or gain output ratio, GOR, of ~60) and high water vapor flux (i.e., >60 L m−2 h−1). We conclude by highlighting promising applications of HPMD for MLD/ZLD, enabled by its high energy efficiency, low capital cost, and modularity. • We develop a novel heat-pump assisted membrane distillation (HPMD) technology. • Energy efficiency of HPMD is comparable to MVC and significantly greater than conventional MD. • HPMD can simultaneously achieve superior energetic and kinetic efficiencies. • HPMD has the potential to be widely applied in minimal/zero liquid discharge processes. [ABSTRACT FROM AUTHOR]

Treatment and management of produced water are of great significance but critical challenges remain due to the huge quantity and complexity of the liquid waste. Here we propose and demonstrate an integrated membrane based system combining electrodialysis, nanofiltration and membrane distillation (ED-NF-MD) for highly efficient treatment of oilfield produced water. Our new system enables zero liquid discharge (ZLD) by concentrating the produced water to an extremely high concentration (up to 373,000 mg/L) at a high water recovery of 99.8% without chemical (e.g. soda or anti-scalants) adding. To the best of our knowledge, such performance is the highest in terms of the final concentration and water recovery among various ZLD technologies. ZLD of our membrane system mainly comes from the metathesis by ED that separates the scaling ions into different streams, thereby creating a scaling-free environment. Basic economic evaluation shows that the total specific energy consumption for ZLD in the whole ED-NF-MD system includes a minimal electrical energy requirement (33 kW·h/m3) and a large thermal energy requirement for MD (154 kW·h/m3). The novel membrane based system shows great potential in realizing real ZLD in produced water treatment by minimizing scaling and thus highly concentrating the feed solution. Unlabelled Image • We demonstrate a new integrated membrane system for produced water treatment. • Our membrane system enables zero liquid discharge without adding chemicals. • High final concentration and high water recovery are achieved. • A scaling-free environment is achieved by electrodialysis metathesis. [ABSTRACT FROM AUTHOR]

Desalination is known to have considerable energy, economic, and environmental impacts. Treatment trains are receiving increased interest for their potential to meet produced water standards while both minimizing impacts and increasing the range of eligible input salinities. However, determining which technologies to combine and predicting their performance is both difficult and case specific. This research will present a unique hybrid-modelling framework (DESALT) for evaluating and comparing desalination treatment trains based on the same customizable inputs. This comprehensive discrete-based approach generates treatment trains and then systematically evaluates them using physics-based evaluation methods that are reflective of changes in operating conditions. DESALT also accounts for technology limitations, product water requirements, and user preferences. The modelling outputs are filtered using a combination of a Pareto front analyses and DEA decision support. The result is a list of eligible and preferred treatment trains with their corresponding operating conditions. The framework's performance was tested by applying two different technologies (electrodialysis and brackish water reverse osmosis) to a brackish water case study. While the methodology was able to capture the trade-offs between treatment trains and individual technologies, the results are highly reliant on the accuracy of the evaluation methods used. • Comparison of treatment trains using the same input criteria under varied operating conditions. • Model includes superstructure design, technology specific evaluations, multiple criteria points, and decision-support tool. • Combines physical equation based modelling of desalination technologies with generalized input criteria. • Decision support includes filtering, reducing, and sorting viable treatment trains to present those that perform best. • Decision support expands outside of general functionality to include environmental and sustainability indicators. [ABSTRACT FROM AUTHOR]

Desalination of produced water in the gulf petrochemical industry is a continuing challenge to major research groups in the field. With a focus on produced water from desalination plants, it has become crucial to define and follow specific protocol in wastewater purification technologies. In this work, an optimized guideline for direct contact membrane distillation (DCMD) was developed and implemented. A bench-scale DCMD unit was performed under optimum process parameters of feed and distillation inlet temperatures of T Feed = 60 °C and T Dist = 20 °C, respectively. A low flow rate of 0.03 L/min was used to avoid wetting of the fabricated membrane. A hydrophobic polystyrene flat sheet was prepared in the labs using a custom-made electrospinning apparatus. The effect of varying concentrations on the hydrophobic polystyrene membrane was studied using a high concentration brine feed (C1 ≈ 75,500 ppm) and another feed of lower concentration (C2 ≈ 25,200 ppm). A high salt rejection rate of 99% was achieved. The morphological structure, pore size and fiber length was analyzed using SEM. Conductivity measurements have confirmed an improved permeate quality of 99%. Thus, as per the DCMD performance of the polystyrene membrane, the generated permeate indicates that the membrane performance may have scalable potential contribution to industrial wastewater purification. • Electrospun hydrophobic membranes in direct contact membrane distillation. • Membrane performance with synthetic brine mimics Qatari desalination plants. • Improved permeate quality of 99% and salt rejection up to 99% from thermal brine. [ABSTRACT FROM AUTHOR]

The limited clean water resource has urged the need to extract fresh water from non-conventional sources. Produced water (PW) is a potential source of fresh water, particularly for oil-producing countries experiencing water stress issue. The engagement of membrane-based desalination technology in the field of PW treatment brings about new possibility of water reclamation. This review highlights the state-of-the-art membrane-based technologies including both stand-alone and their hybrid system, for PW treatment and reclamation. While reverse osmosis continues as a reliable option for PW treatment, emerging technologies like forward osmosis and membrane distillation have attained increasing attentions from the desalination community. To pave a way for practical applications of membrane technologies for PW desalination, the recent advances in term of membrane properties improvement, operating condition optimization, and membrane cleaning protocols are reviewed. Finally, the challenges and future outlooks of current PW desalination technologies are also highlighted. • State-of-the-art PW desalination technologies are reviewed. • Merits and limitation of RO, FO and MD PW desalinations are discussed. • Strategies of improving membrane-based PW desalination are reviewed. • Challenges are identified and the future perspectives are proposed. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) has shown promise for desalination of produced water (PW), but there are very few studies reported on the performance of MD with real PW and the characteristics of the fouling and scaling in MD. Among different MD configurations, sweeping gas MD (SGMD) is the least studied configuration. Here we report the application of SGMD for treating high-salinity PW (123 g L−1). The SGMD operating conditions were first carefully optimized through pure water MD experiments by varying operating conditions. The flux evaluation was accompanied by a detailed Aspen Custom Modeler simulation based on the electrolyte-NRTL thermodynamic model to better understand the heat and mass transfer in the feed and permeate channel. Supported by experiments, modeling results confirmed the partial condensation of the vapor in the permeate channel. Additionally, it was concluded that the saturation of the sweeping gas is controlling the overall mass transfer through the membrane. Selected membranes and optimized conditions were then used to conduct short-term and long-term performance tests with PW. In long-term MD test, the concentration of the PW increased by a factor of two (50% water recovery), while the membrane exhibited small flux decline. Elemental analysis showed that strontium and sodium were the major scalant compounds. • Aspen Custom Modeler (ACM) with e-NRTL thermodynamic model was used to predict the SGMD flux. • Modeling and experiments suggest that the sweep gas in the permeate side controls and limits the SGMD flux. • Produced water was concentrated to 250,000 mg L-1, and no membrane wetting was observed in long-term SGMD tests. • Characterization of the fouled and scaled membranes showed that organic matter can increase the possibility of membrane wetting. • Although at low concentration, strontium and iron were found to be the major scalants on the scaled membranes. [ABSTRACT FROM AUTHOR]

Concentration polarization and fouling hamper the desalination of polymer-flooding produced water (PFPW) via electrodialysis (ED). This water is an abundant by-product from the oil and gas industry. A common technique to mitigate both problems is the application of pulsed electric field (PEF), which consists in supplying a constant current during a short time (pulse) followed by a time without current (pause). Accordingly, this work evaluated the application of PEF during the ED of PFPW to improve the process performance and to reduce fouling incidences. The experimental work consisted in performing ED batch runs in a laboratory-scale stack containing commercial ion exchange membranes. Synthetic PFPW was desalinated under different operating regimes until a fixed number of charges were passed. After each experiment, a membrane pair was recovered from the stack and analyzed through diverse techniques. The application of PEF improved the ED performance in terms of demineralization percentage and energy consumption, the latter having reductions of 36% compared to the continuous mode. In general, the shorter the pulses, the higher the demineralization rate and the lower the energy consumption. Regarding the application of different pause lengths, longer pauses yielded lower energy consumptions, but also lower demineralization. Amorphous precipitates composed of polymer and calcium fouled most on the anion and cation exchange membranes, independently of the applied current regime, but in a moderate amount. Finally, the present study relates the observed effects of PEF application to the electrophoresis and diffusion of HPAM, and shows that PEF is a sound option to enhance the desalination of PFPW. Unlabelled Image • Polymer-flooding produced water desalination enhanced by pulsed electric field. • Performance improved in terms of degree of desalination and energy consumption. • Transport numbers of Ca2+ and Na+ affected under certain pulsed regimes. • Fouling was not severe, even when the feed solution contained crude oil. • Best results obtained for the regime t on / t off = 1 s/1 s. [ABSTRACT FROM AUTHOR]

In this study at a full-scale desalination installation seven types of commercially available cartridge filter (CF) elements were evaluated in terms of: (i) water production volume (m3), (ii) produced water quality, and (iii) operational cost (€cent/m3). The cost of optimal CF replacement time relative to increased CF pressure drop was determined for three electricity tariffs (0.05, 0.15, and 0.25 €/kWh) to assess further cost reduction. CF 1 was able to achieve the highest water production rate, the lowest produced water SDI, and the lowest cost of operation. The total costs of cartridge filtration varied between 1.22 and 1.70 €cents/m3 produced water, depending on the CF type. Replacing the worst-performing CF type by the best-performing CF type would reduce operational CF costs by about 39.3%, enabling a cost saving of 0.48 €cents/m3 produced water, emphasizing that selection of the right CF enables a large reduction of cartridge filtration costs. Moreover, depending on the electricity tariff an additional 2–16% cost reduction can be achieved by replacing CFs at an optimal time. At high energy cost, it may be more economical to replace cartridge elements more often to reduce the increased cost associated with the required higher pressure. Unlabelled Image • Seven types of high flow cartridge filters evaluated for product quantity and quality. • The best CF resulted in 34% higher water quantity with better water quality. • Differential pressure increase across the CF results in higher energy consumption. • Selecting the right CF type can reduce up to 39% of CF water production cost. • CF replacement frequency is optimized depending on energy cost. [ABSTRACT FROM AUTHOR]

This paper focuses on a novel heat pump powered desalination system, in which the heat pump is coupled into the humidification dehumidification desalination subsystem with open-air, open-water configurations. Based on the conservation equations in accordance with the flow streams within the system, thermodynamic investigations, at the energetic and entropic viewpoints, are conducted. Thereinto, parametric analysis of the HPPDS is first achieved to assess the influence extents from the critical conditions, and then the thermodynamic optimization based on the algorithm of particle swarm optimization is also completed. The research results indicate the best system performance reaches 89.27 kgh−1 for the water production and 4.17 for the gained-output-ratio. The performance of the heat pump powered desalination system is very sensitive to the alternation of the prescribed parameters, except the dehumidification effectiveness. Finally, the maximum water production and gained-output-ratio can be optimized to 150.75 kgh−1 and 8.12, respectively, and a fully coupled heat pump powered desalination system is acquired without an auxiliary heater. With respect to the economic performance, the cost of the fresh water is gained as 0.016$L−1 at the optimized conditions. • A novel desalination system with HD desalination and heat pump unit coupled is proposed. • An evaporator is laid to recover the latent heat of the discharged air and produced water. • Energetic and entropic analysis of the desalination system is achieved. • Influences from the effectiveness, inlet humidity, PR, PTD con and TTD e on the desalination performance are revealed. • Particle swarm optimization is conducted into the HD desalination field. [ABSTRACT FROM AUTHOR]