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This study assesses environmental impacts of reverse osmosis and algae-based biodesalination in four scenarios using a life cycle assessment (LCA) approach. These scenarios encompass (1) a multistage conventional pre-treatment desalination system, (2) immobilized algae-based hybrid desalination system, (3) suspended algae pre-treatment hybrid system, and (4) an attached growth algae-based hybrid system with a low-pressure reverse osmosis (LPRO) system. The assessment integrates the ReCiPe and USEtox 2.0 methods, examining diverse phases such as construction, operation, waste treatment, and chemicals. The impact analysis unveils waste treatment as a significant contributor in Scenario 1. In Scenarios 2 and 3, the operational phase, driven by chemical consumption, emerges as a major factor by 60–70 %, causing environmental damage. Scenario 4 showcases superior environmental performance, notably in global warming potential, freshwater eutrophication, marine eutrophication, ozone layer depletion, and fossil resource scarcity. Results highlight that Scenario 2 and Scenario 3, utilizing immobilized and suspended growth biodesalination, do not align with favorable LCA outcomes. Overall, Scenario 4 displays the least environmental impact and a favorable carbon footprint. The study advocates pipeline brine disposal due to its greater convenience and lesser environmental damage. A sensitivity analysis emphasizes the advantages of shorter transportation distances for optimal brine disposal from the desalination plant to the sea. • Assessed environmental impacts using LCA for algae-based seawater desalination • By consuming CO 2 during photosynthesis, algae help reduce GHG emissions. • Biodesalination presents three energy-efficient scenarios for seawater treatment. • Algal biomass is hydrothermally liquefied, generate electricity in last 3 scenarios. • Decreasing brine disposal distance reduced terrestrial ecosystem impact by 20 %. [ABSTRACT FROM AUTHOR]

This study presents a novel data-driven optimal control method to minimize the cost of Convection-Enhanced Evaporation (CEE) systems under time-varying weather conditions. CEE is the approach of evaporating water from saline films (brine) on packed evaporation surfaces by air convection. Here, operating variables (brine injection rate, brine temperature, and air speed) are actively controlled as a function of current ambient conditions and daily weather forecast. The controller optimizes the process operation variables based on a dataset consisting of Pareto fronts, obtained in advance by solving a set of optimization problems. Three optimal operation strategies are presented: (1) real-time selection of operating variables, (2) predictive scheduled operation, and (3) hybrid wind-fan operation. The effectiveness of the proposed strategies was assessed through two case studies with distinct geographical locations and weather conditions: Alamogordo, New Mexico, and Minneapolis, Minnesota. The results show significant cost-saving potential relative to static operation. Predictive scheduled operation resulted in an annual average operating costs of $0.91/m3 and $6.63/m3 in Alamogordo and Minneapolis, respectively, with the higher costs in Minneapolis a result of the added thermal energy required to prevent freezing in winter. [Display omitted] • Data-driven optimal control methods are presented. • Controller predicts optimal operation schedule based on weather forecast. • Hybrid wind-fan operation reduces electric energy use. • Operation in extreme cold weather • Predictive, time-varying operation gave highest cost reduction. [ABSTRACT FROM AUTHOR]

Freeze desalination (FD) is a method in which saline water is cooled below its freezing point and freshwater is separated from the brine in the form of ice crystals. FD is relatively insensitive to the salinity of the feed solution, making it suitable for desalination of high concentration brines such as the brine rejected from the seawater desalination plants. The design of the FD system and the thermochemical behavior of the brine upon freezing are critical factors in the energy performance of this method. To date, thermochemical properties of the concentrated seawater during cooling, such as the threshold of formation of ice and salt-hydrates and their corresponding cooling load of formation, are not well known. Likewise, the optimal configuration of the FD system to achieve the maximum energy efficiency has not been investigated. This work provides comprehensive data about the cooling load of freezing of concentrated brine rejected from seawater desalination plants along with the threshold of formation of ice and salt-hydrates backed-up by validation. Furthermore, the optimal configuration of the FD system is identified and the effects of the compressor isentropic efficiency and effectiveness of the system's heat exchangers on the work consumption of the FD system were investigated. • A new freeze desalination system configuration is proposed adopting extensive cooling energy recovery strategy. • A co-simulation framework has been developed and validated to simulate the freeze desalination system. • The energy performance is thoroughly investigated and compared with the corresponding published benchmark values. • The thermochemical behavior is presented for the treated brine considering a range of brine feed concentrations. • Comprehensive data about the energy performance is presented through analysis considering the key sources of irreversibility. [ABSTRACT FROM AUTHOR]

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]

This study reports a novel approach of resource recovery from co-managing two geographically co-located and chemically complementary wastewaters using a pilot-scale treatment process. Designed to treat flue gas desulfurized (FGD) effluent from combustion powerplants and produced water (PW) from energy industries, the process consists of soda-ash softening, nanofiltration (NF), and reverse osmosis (RO). Recovered products are barite, calcite, and low-salinity water. Using field-collected waters, the results show that softening at pH ≈ 8.5 produces calcite (yield: ~ 30 kg/m3 treated water), a chemical used as SO₂ (g) scrubbers. NF treatment under an applied pressure of ~ 3.5 MPa yields a permeate stream laden with monovalent ions (water recovery ~ 60 %) and a concentrate stream with a sulfate concentration ~ 1.8 times of the feedwater concentration. Mixing the NF concentrate and PW at a volumetric ratio of 1.0 precipitates a high-density barite material (4.1 g/cm3, yield: ~ 7.5 kg/m3 mixture) – a critical mineral commonly used as a weighting agent in drilling. The RO treatment recovers >64 % water as the permeate, which can be readily used as cooling make-up water at the powerplants. The RO concentrate stream can be further processed in a thermal evaporative system for additional water recovery and brine production. [Display omitted] • FGD effluent and PW have complimentary chemistries for critical mineral recovery. • FGD and PW co-treatment recovered barite, calcite, and low-salinity water. • Successful pilot-scale operation demonstrated feasibility of the co-treatment approach. [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]

Cooling tower blowdown from thermoelectric power plants and produced water from hydraulic fracturing may soften when mixed due to the complimentary chemistry of the two wastewaters. The potential benefit of low effort softening warrants the investigation of a cotreatment process concerning these industrial wastewaters. The synergy is expected to lessen chemical demand for softening and further enable sustainable practices such as designing for a zero-liquid discharge (ZLD) process. The treatment process may then provide a treated effluent suitable for use as blowdown makeup. In this study, the feasibility and effectiveness of a cotreatment train is explored through simulation of chemical softening, filtration, reverse osmosis (RO), multi-effect distillation (MED), and electrolysis unit operations within a comprehensive process model. Innovative modeling strategies are necessary to result in a meaningful process model when considering the significant complexity of the water chemistry for this treatment train. Through the methodology described in this work, a feasible process design is presented as a base case for treatment of experimentally characterized blowdown and produced water samples obtained in the northern Appalachian region. Thereafter, the base case also establishes a platform for more detailed process analyses of different scenarios in future work. Detailed descriptions of modeling methodologies, process design decisions, and simulation results are provided as a perspective on comprehensive modeling of multi-technology treatment trains for complex feedwaters. With the results of the cotreatment simulation, it is determined that the total water recovery of the process may serve to completely makeup the blowdown rate and partially make up the evaporative losses of a theoretical thermoelectric plant's water demand. This complete recovery is evaluated to require 18,343.531 kW of a chemical energy equivalent, 1184.971 kW of electricity, and 68,126.291MJh − 1 of power plant steam to result in 408.532m 3 h − 1 of treated water effluent at a quality of approximately 0.135gL − 1 total dissolved solids for the base case design. • Blowdown and produced water cotreatment is explored through simulation. • A unique framework is demonstrated for a high-fidelity, multi-technology model. • A base case process model is established for future cotreatment analyses. • The 0.135 g/ L TDS effluent may completely makeup power plant blowdown. • Energy demands are 18,300 kW chemical, 1180 kW electricity and 68,100 MJ h−1 steam. [ABSTRACT FROM AUTHOR]

Humidification-dehumidification (HDH) desalination systems are popular among researchers due to their simple structure, ability to operate with low-grade and renewable energy sources, and the capacity to work with high-concentration water. This paper presents a thermodynamic and thermoeconomic analysis of an HDH system with a multi-stage bubble column dehumidifier. There was a lack of economic studies on bubble column dehumidifier systems in previous literature; also, no research had examined the impact of different geometric and temperature parameters on the entire system's performance. The fixed surface method was used to model the humidifier and dehumidifier, and the effect of mass flow rate ratio, top and bottom temperature, pipe length within each dehumidification stage, and the number of dehumidifier stages on the system's performance was studied. System performance was compared under various conditions, including gain output ratio (GOR), water production, and cost of produced freshwater. The highest GOR is obtained in the highest pipe length and the highest number of dehumidifier stages. Increasing the length of the pipe and the number of dehumidification stages increases the cost, so achieving the lowest cost of produced water is a compromise between higher cost and higher efficiency. The system achieved a GOR of 3.03, the lowest cost price of produced water is 18.29 $ m 3 , and the highest acheived exergy efficiency is 22.4 %. • An HDH system with multi-stage bubble column dehumidifier is proposed. • A thermoeconomic model has been developed to analyze this system. • A novel approach is introduced for the purchase cost of a bubble column dehumidifier. • Effects of physical and geometric parameters on system performance are investigated. • The unit cost of water production in different conditions is presented. [ABSTRACT FROM AUTHOR]

Water management in oil and gas production industries is one of the important issues due to the requirement of huge amount of freshwater in process and generation of large amount of waste stream called produced water (PW), which is 70 % of total wastewater. Due to the PW is the largest waste stream generated from oil and gas production process, the recycle of produces water can reduce the supply of freshwater from other sources of water such as river and lake, and negative influence on environment caused by water intake and disposal of the PW. In order to recycle/reuse the PW, it is commonly treated by physical, chemical and biological methods such as adsorption, flotation, sand filter, evaporation, electrodialysis and membrane-based processes. This review focuses on the research state of conventional and emerging technologies for water management in oil sands field for treatment of PW. It also addresses the real water management strategies in oil sands plant in Canada. The new strategies for water management are discussed through the comparative analysis on the current state of technologies and strategies. • The status of water management and produced water treatment in oil sands plant was reviewed. • Produced water treatment is inevitable to mitigate problems on freshwater supply and environment. • Membrane shows good performance to remove the contaminants in produced water with high water quality. • Control of the negative effects of scalants is essential for proper water management with high water recovery. [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]

Membrane distillation (MD) is a promising technique for desalinating hypersaline brine, such as produced water (PW). To date, fouling and scaling have remained as major challenges for MD implementation. In this study, chlorine dioxide combined with induced air floatation (ClO 2 -IAF) was systematically investigated as a pretreatment prior to MD. First, the ClO 2 generation based on sodium chlorite and hydrochloric acid was optimized to maximize the on-demand ClO 2 production. The maximum production yield of 18.4% was obtained with 4 wt.% NaClO 2 and 20 wt.% HCl solutions, with a molar ratio of 1:1.25. Then, two real PW samples were pretreated, and removal efficiencies for total suspended solids (TSS), turbidity, iron, and total organic carbon (TOC) were comprehensively studied by varying the ClO 2 dosage between 6 and 91 mg/L. The ClO 2 -IAF pretreatment displayed TSS and turbidity removals above 90% and TOC removal close to 55%. The PW constituents such as benzene, toluene, ethylbenzene, xylene (BTEX), and total petroleum hydrocarbons (TPH) were analyzed and quantified throughout the cascade of the treatments. The volatiles like BTEX were mainly removed by air floatation, while saturated hydrocarbons such as TPH were retained by the hydrophobic membrane. The MD long-term stability without any in-place cleaning was evaluated, and the membrane withstood for twenty two days without wetting, suggesting that optimizing oxidation pretreatment is critical for mitigating the fouling in MD. Results suggest that organic fouling in PW could be effectively reduced by the pretreatment, but further treatment is required to mitigate the scaling, which resulted in MD wetting. • Evaluated chlorine dioxide pretreatment for the treatment of real produced water • Pretreated produced water was desalinated using membrane distillation. • With optimal oxidant dosage, long-term MD continued for extended period. • Studied organics removal efficiency through the cascade of treatments [ABSTRACT FROM AUTHOR]

Proper management and treatment of produced water has emerged as a big challenge for oil and gas industry. Increasingly stringent environmental regulations and economic constraints are compelling the use of more advanced treatment methods. Membrane operations are gaining significant interest for this application due to their broad range of separation capabilities, high efficiency and low operational cost. Commercially less-adopted membrane operations, such as membrane distillation (MD) and membrane crystallization (MCr) are gaining significant interest for produced water treatment due to their almost concentration-independent performance and less fouling potential. The current study analyzes the performance of an integrated microfiltration (MF) and direct contact membrane distillation (DCMD)/membrane crystallization (MCr) system for freshwater and minerals recovery from produced water. Based on the experimental data, thermodynamic/exergetic/quantitative analyses have been performed. Performance of the integrated processes has been compared with the conventional multi-stage flash (MSF) in terms of process intensification metrics . [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]

Forward osmosis (FO) has recently been considered as a means of treating or concentrating produced water because of its low fouling propensity at high recoveries. However, while numerous studies have been published on produced water treatment with FO, many benchtop studies use “coupon” type membrane systems that can only operate at limited recovery because of large holdup volumes and small membrane areas. Newly available commercial elements could be used, but working with such dirty waters would be costly as elements would need regular replacement. In this work, we propose a new method for testing the efficacy of forward osmosis that enables high water recovery using coupon based testing systems. Our hybrid dead-end/cross-flow filtration cell operates in a dead-end mode on the feed side and a cross-flow mode on the draw side, maximizing the recovery of the feed while minimizing dilution of the draw. We demonstrate the value of this type of testing apparatus using an unprocessed produced water provided by Chevron Corporation. This water, which contains small quantities of oil and approximately 7500 ppm total dissolved solids (TDS), could be concentrated by up to 20 fold using this approach. [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 waters (PWs) are oilfield waste streams rich in minerals and hydrocarbons whose production rate is largely increased in last decades following the corresponding increase of energy demand. The high salinity level of PWs inhibits the adoption of cheap biological treatments. Also, desalination techniques based on osmotic membranes would require severe pre-treatments. As an alternative, Reverse ElectroDialysis (RED) and Assisted Reverse ElectroDialysis (ARED) are here proposed for the first time to reduce the salinity level of PWs. RED may also guarantee an operation cost reduction thanks to its energy generation. An ad-hoc model for RED and ARED is here developed in order to deal suitably with PWs. This is done by a calibration and validation with experimental data purposely collected via RED and ARED units fed by real PWs. The model is integrated with economical equations and a techno-economic analysis is carried out in order to identify the best configuration for the desalination purposes. Results suggest that ARED operation mode is the best option guaranteeing a minimum in the controlled dilution cost corresponding to a 1.32 € per m3 of PWs treated, thus leaving room for an affordable future implementation of more sophisticated treatment chains based on bioremediation. [Display omitted] • RED and ARED are proposed for the first time to reduce the salinity level of PWs. • An ad-hoc model is developed and validated against purposely performed experiments. • An extensive techno-economic analysis is carried out to identify optimal conditions. • ARED operation mode is found to be the best option for the desalination purposes. • Optimized conditions lead to a minimum cost of 1.32 € per m3 of PW treated. [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]

Solar water desalination is still one of the most efficient techniques in water and wastewater treatment. In the present study, an evacuated tube collector (ETC) was used as the basin of the solar still. A cube-shaped glass condenser was attached on top of the ETC for vapor condensation. The main purpose was to investigate the effect of condenser geometry, including volume, surface, and wall thickness on distilled water production. The optimal conditions to produce a maximum volume of distilled water were determined using response surface methodology (RSM), based on the Box-Behnken design (BBD) model. All selected operating factors significantly affect the volume of water produced by solar desalination. The maximum volume of produced water was 7.231 kg.m−2.day−1, which was obtained at the condenser volume of 2940 cm3, the condenser wall thickness of 4 mm, and the condenser surface of 3360 cm2. R 2 and R adj 2 values in the selected model were 0.9934 and 0.9815, respectively. The validation experiment confirmed the high accuracy of the BBD model for predicting the optimal conditions to achieve the maximum amount of produced water. [Display omitted] • The modified ETC, on which embedded a cube-shaped glass condenser, was fabricated. • The effect of volume and surface of the condenser on V.W separately was evaluated. • The operational parameters affecting V.W were optimized based on the BBD model. • The influence of the condenser surface was more evident than other operating factors. • In modified ETC, the specific surface area of the condenser was increased. [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]

In the past decade, thanks to their ultrafast water transport and excellent molecule sieving properties, researches on graphene oxide (GO) based membranes have developed rapidly. However, the researches were mainly conducted in laboratory scale, and so far, there is no real on-site wastewater treatment experiments using GO-based membranes in pilot-scale reported. Herein, we report an on-site pilot trial study using the ultrathin GO membrane to treat a dyehouse effluent. The performance of the GO membrane was studied to provide insight for the large-scale applications. A long-term pilot trial of 45 days was conducted to investigate the long-term stability of the GO membrane. The rejection of mixed salts in the dyehouse effluent can be maintained at about 77.0%. And most typical organic pollutants in the effluent can be effectively removed. The quality of the produced water fully meets the requirements of the Chinese Industry Standard FZ/T 01107-2011. The results showed that the GO membrane has excellent purification efficiency for the real dyehouse effluent and excellent stability during the long-term trial run. The pilot scale study suggests that the GO membrane is highly feasible to treat the dyehouse effluent in a large industrial scale. • Successful pilot trial of GO-based membrane for high salinity dyehouse effluent. • GO-based membrane showed high separation efficiency on the inorganic/organic solutes. • GO-based membrane has excellent long-term stability and anti-fouling property. [ABSTRACT FROM AUTHOR]

Substantial quantities of produced water generated during the extraction of oil and gas from unconventional reservoirs present significant environmental concern and increase the operating cost for this industry. Membrane Distillation (MD) can serve as a potential solution for beneficial reuse of produced water by generating high-quality permeate and reducing the volume of produced water requiring disposal. This study investigated treatment of produced water from Permian Basin in both laboratory and pilot-scale studies. Laboratory tests revealed the potential to successfully recover 50% of produced water although some increase in permeate conductivity was observed due to the passage of ammonia from the feed side. Initial pilot-scale test with filtration of raw produced water as the only pre-treatment step led to precipitation of SrSO 4 , NaCl, and Fe in the system once the solubility limits for these salts were exceeded. However, chemical pretreatment that included pH adjustment, aeration, and barite precipitation, allowed successful steady-state operation of the AGMD pilot system for 5 days where the produced water was concentrated from 127 g/L to 255 g/L (~50% water recovery) while recovering high quality permeate. Overall, greater than 99.7 % salt rejection was achieved with the average permeate flux of 1.86 LMH. Mass balance analysis suggested potential Ba and Ca precipitation in the system but there was no impact on AGMD performance and permeate quality during 5 days of continuous operation in the field. • Laboratory-scale DCMD studies confirmed feasibility of produced water treatment\ • Demonstrated steady-state AGMD 0.8 gpm pilot-scale operation for 120 h • Achieved 50% water recovery with 99.7% ion rejection with real produced water • Pretreatment of produced water to remove iron and sulfate may be required. • Precipitation of Ba and Ca in the system did not affect AGMD performance. [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]

A superomniphobic polyvinylidene fluoride (PVDF-F) membrane was fabricated through electronspinning to obtain an excellent antiwetting and antifouling property for the effective and efficient treatment of real produced water. Compared with pristine PVDF and hydroxyl functionalized PVDF (PVDF-O) membrane, PVDF-F membrane had a larger pore diameter, while its pure water flux was found to be lower than both. Neither liquids with high surface tension (water, ethanol) or low surface tension (sodium dodecyl sulfate (SDS) as surfactant, mineral oil) could wet the PVDF-F surface even up to 3 min of contact. During membrane distillation (MD) of 3.5 wt% of aquoues NaCl solution, PVDF-F could withstand 0.4 mM SDS solution without any wetting as seen from the conductivity of the permeate, which was not the case for the PVDF and PVDF-O membranes. After 18 h of MD operation using produced water, a significantly thick fouling layer was found on the PVDF and PVDF-O membranes containing Ca 3 (PO4) 2 , Sr 3 (PO 4) 2 and Mg 3 (PO 4) 2. However, PVDF-F had a very thin and reversible organic fouled layer, causing only 40% reduction in permeate flux and with a low permeate conductivity of 20 μS cm−1. This layer was easily removed by cleaning using distilled water and 80% of the flux was recovered. On the 2nd and 3rd MD cycle, the reduction in permeate flux was within 10%. The superomniphobic PVDF-F nanofibrous membrane was run for three successful consecutive MD cycles during produced water processing without any significant fouling as well as wetting. • Modified nanofibrous membrane was fabricated through chemical vapor deposition. • Superhydrophobic and superoleophobic surface was developed for MD. • The modified membrane had an excellent antiwetting and antifouling property. • High salinity produced water from hydraulic fracturing process was treated. • The modified membrane exhibited high separation efficiency with good regeneration. [ABSTRACT FROM AUTHOR]

The presence of fine solids and dissolved organics in produced water from Steam-Assisted Gravity Drainage (SAGD) process can potentially block pressure vessels and cause fouling and corrosion in steam boilers. Ceramic membranes in tubular configurations with pore sizes of 20 kDa, 50 nm and 100 nm were investigated for the removal of solids and dissolved organics from boiler feed water (BFW). The original BFW sample contained 125, 1300 and 20 mg/L of oil and grease (O&G), naphthenic acids (NAs) and total suspended solids (TSS), respectively. It was found that lowering the pH of the BFW to 4 prior to membrane treatment increased the permeate flux and also eliminated operating drawbacks such as foam formation. Among all the investigated membranes, the Al 2 O 3 membrane with 100 nm pore size showed the best performance in terms of flux and removal efficiencies as no detection of total suspended solids was observed in the permeate streams while achieving a high removal efficiency of 80% and 95% for O&G and NA, respectively. [ABSTRACT FROM AUTHOR]

The internal reuse of shale gas flowback and produced water (SGFPW) can ease the pressure on treatment and management costs and freshwater supply. Internal reuse of SGFPW based on membrane treatments is faced with major challenges of the divalent ion and organic pollutant removal as well as membrane fouling control. To solve these problems, a green and efficient adsorbent of porous biochar aerogel (PBA) was combined with ultrafiltration (UF)-nanofiltration (NF) for SGFPW internal reuse in this study. The removal performance of dissolved organic carbon (DOC, >85.9%) and divalent ions (>70.6%) for three SGFPW showed feasibility of PBA-UF-NF process for internal reuse. Three-dimensional excitation-emission matrix (3D EEM) fluorescence spectrum, organic fractionation and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory were used to identify the organic composition of SGFPW and analyze membrane fouling. PBA tended to adsorb hydrophobic fraction and alleviated UF membrane fouling caused by attractive hydrophobicity. NF membrane fouling was mitigated due to the increased polar repulsion as well as the decreased synergistic fouling between organics and divalent cations through the reduction of DOC by PBA. PBA-UF-NF process had good performance on organic pollutant and divalent ion removal with decreasing membrane fouling, presenting potential to treat SGFPW onsite for internal reuse. [Display omitted] • Porous biochar aerogel (PBA) adsorption-UF-NF was suitable for varied SGFPW. • >85.9% of DOC and >70.6% of divalent ions were removed. • PBA pretreatment effectively mitigated membrane fouling. • XDLVO theory indicated polar repulsion alleviated UF and NF membrane fouling. • DOC reduction could alleviate the hybrid fouling of NF membrane. [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]

Drinking water supply sustainability is one of the biggest challenge of the century, necessitating efficient and economical technologies for water purification. ZnO atomic layer deposition (ALD) modified membranes were developed for treating produced water from wells in Oklahoma, as a model of produced water, having very high salt and oil content. ZnO ALD membranes increased hydrophilicity with an oil contact angle increasing from 165° for an α-alumina support to 171° for a ZnO ALD membrane (120 cycles), which induced a dramatic rise in the pure water flux from 148 to 192 L m−2 h−1. ZnO ALD on the membranes enhanced Total Organic Carbon (TOC) rejection from 96% to 99% and decreased Total Dissolved Solids (TDS) content from 53,205 ppm to 10 ppm. It was found that the average roughness (S a) was 509 nm for the pristine α-alumina support and was reduced to 332 nm for the ZnO ALD membrane (120 cycles). Additionally, the anti-fouling property of membranes with flux recovery ratio increased from 93% to 99%. Overall, the ZnO ALD membrane showed great potential to purify produced water. • ZnO atomic layer deposition modified membranes were prepared. • ZnO ALD membranes enhanced oil and salt rejection of produced water. • ZnO ALD membranes exhibited excellent fouling-resistant property. • ZnO ALD membranes showed good reusability property. [ABSTRACT FROM AUTHOR]

The harmful effects arisen from the discharge of saline wastewater have become more evident in recent years and therefore drawn much public concerns. Saline wastewater, including produced water, tannery wastewater, textile wastewater and aquaculture wastewater, contains various organic pollutants and inorganic dissolved ions. These saline wastewaters can be treated, not only to meet the discharge standard but also to offer the opportunities for water reuse and nutrient recovery. Membrane technology is a promising technology that offers attractive solutions for effective saline wastewater treatment and resource recovery. With the tremendous development made in this realm, this review is set to provide a frame of state-of-the-art approaches for saline wastewater treatment based on membrane technology and stimulate ideas to enhance the treatment efficiency and sustainability in these related works. The unique features, strengths and limitations of pressure-driven, osmotically-driven, thermally-driven and electrically-driven membrane processes in treating saline wastewater and resource recovery are discussed. This review aims to consolidate the literature related to membrane technology as a versatile tool for saline wastewater treatment, as well as to identify the current research gaps and areas of improvement related to this field. • Various membrane-based separation processes for saline wastewater treatment and resource recovery are discussed. • Pressure-driven membrane processes are reliable and effective for saline wastewater treatment and recovery. • Forward osmosis, membrane distillation and electrodialysis are feasible alternatives. • Integrations among membrane processes or with conventional treatment processes provide more holistic solutions. • The current research gaps and the future directions are highlighted. [ABSTRACT FROM AUTHOR]

Pressure-retarded osmosis (PRO) is a promising membrane technology for harnessing the osmotic energy of saline solutions. PRO is typically considered with seawater/river water pairings however greater energy can be recovered from hypersaline solutions including produced water (PW) from the petroleum industry. One of the major challenges facing the utilization of hypersaline PW is its high fouling propensity on membranes. In this unique experimental evaluation, real PW from different sites was pretreated to varying degrees: i) minimal, ii) intermediate, and iii) extensive. The treated effluent was subsequently used for PRO testing and fouling rates were assessed for different membrane configurations over multiple cycles. Commercial grade flat sheet (FLS) coupons and novel hollow fiber (HF) modules were compared to validate the lower fouling propensity of HF membranes in PRO application. When minimally pretreated PW (10-micron cartridge filtration (CF)) was tested in FLS mode, severe membrane fouling occurred and the PRO flux decreased by 60%. In contrast, HF modules showed <1% flux decrease under both minimal and intermediate pretreatment schemes. Extensive pretreatment (1-micron CF, dissolved air flotation (DAF), powdered activated carbon, and microfiltration) reduced FLS PRO flux decline to <1%. These results confirm that PW can be treated to suitable levels for PRO application to avoid membrane fouling. Further validation of these pretreatment methods requires long term pilot testing and techno-economic assessment. [Display omitted] • PRO evaluation on hypersaline produced water (PW) from the petroleum industry • Real PW from different oil production sites was used for testing. • Several levels of pretreatment including physical and physicochemical processes • PW can be treated to suitable levels for PRO application to avoid membrane fouling. • Novel hollow-fibers are less prone to fouling compared to flatsheet membranes. [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]

Abstract: In this paper, the hydrodynamic behaviour of oil field wastewater treated by ultrafiltration process was studied. The results were obtained as: under certain operation parameters, the rejection coefficients of both oil/water and turbidity are maintained over 0.96 and 0.97, respectively; while, temperature has no obvious effect on the rejection coefficient of oil/water and turbidity. Moreover, the tangential velocity has a positive effect on maintaining a relative high permeate flux, and this effect is even more obvious at higher trans-membrane pressures; meanwhile, the rejection coefficients improved with tangential velocity increasing until 0.4m/s, once the velocity goes beyond this value, the rejection coefficient decreased. [Copyright &y& Elsevier]

Abstract: Large amounts of water are produced during the production of crude oil and natural gas. This water has to be analyzed to realize the correct geological formation. In this work, an extensive analysis of oil field water delivered from Gulf of Suez was carried out to determine the composition of the precipitate formed before starting waterflood operation. Cation and anions are the main interest of this analysis and are carried out using ion chromatography (IC). The data of water analysis have been used as an input data for computer software program. The scale precipitation processes in the bulk solution as well as the tendency rate and inhibitor effectiveness have been determined using jar test methods. The data arising from jar test are compared with the output of the software program to evaluate and quantify the scale precipitation. Also, the mixing waters are analyzed after precipitation to determine the consumed calcium and sulfate ions in presence and absence of inhibitor. It was found that mixing of the injection water and formation water leads to calcium carbonate and barium sulfate scaling at 60% formation water in absence of scale inhibitor. [Copyright &y& Elsevier]

Membrane distillation (MD) has shown strong promise for treating hypersaline produced water (PW) streams. Scaling and fouling on the membrane surface, however, have been identified as major challenges for commercialization and widespread application. The focus of this study was to first identify the nature of foulants and scalants on the membrane surface and then investigate the pretreatment strategies that mitigate the extent of fouling and scaling on the membrane surface. Vacuum MD (VMD) was selected for this study because of its higher flux at more moderate feed temperatures that eventually leads better assessment of fouling and scaling on the membrane surface. VMD flux tests were carried out with three different real PW samples at total dissolved solids concentrations in the range of 120–160 g/L. It was found that an efficient pretreatment prior to MD is required to mitigate the fouling potential of the organic matter, mostly suspended constituents, in PW samples. Suspended organics fouled and quickly wetted the MD membrane. Major conventional treatments, including filtration, oxidation, coagulation, air floatation, and aeration were investigated to pretreat the PW before VMD tests. A comprehensive comparative analysis is presented showing that the ultrafiltration and coagulation pretreatments displayed the best performance in mitigating the fouling and scaling, while oxidative pretreatment was found to be effective in reducing the iron concentration to less than 5 ppm. The surface of scaled membranes was carefully characterized to further evaluate the performance of each pretreatment. The components that had the highest tendency to precipitate on the membrane surface were identified as strontium sulfate, calcium carbonate, sodium chloride, iron oxide, and silica. These findings are supported by thermodynamic estimation of the saturation index. • Membrane distillation proposed for desalinating hypersaline produced water • Suspended organic matter fouls the membrane, leading to immediate membrane wetting. • Pretreatment of produced water required for long-term performance • Fouling and scaling characterized; sulfate and carbonates found as major scalants • Produced water concentrated to 290 g/L and +50% water recovery achieved [ABSTRACT FROM AUTHOR]

Abstract: Fast development of the coalbed natural gas (CBNG) industry in many parts of the western US has resulted in the co-production of potentially saline-sodic waters, hereafter referred to as CBNG water. Management of CBNG water is a major environmental challenge because of its quantity and quality. In this study, the potential utilization of three calcium (Ca2+)-rich zeolites were examined for removal of sodium (Na+) from CBNG waters. The zeolite samples examined were from the St. Cloud (ST) mine in Winston, NM, the Bear River (BR) mine in Preston, ID, and a mine in Arizona (AZ). The zeolite materials were used in adsorption and column experiments to evaluate sorption as a function of water chemistry, particle size and flow rate. Regeneration and potential reuse of the media were also examined. Surrogate CBNG waters that simulated the water chemistry of CBNG waters were used in the different studies. Although the AZ-zeolite is a Ca2+-rich chabazite, results from column studies indicate there was essentially no Na+ exchange, suggesting the Ca2+ is tightly held on chabazite adsorption sites. Results for ST-zeolite and BR-zeolite, which are clinoptilolite zeolites, indicated that a Langmuir model fit the adsorption data well. The maximum adsorption capacities from the adsorption curves for ST-zeolite and BR-zeolite were 9.6 and 12.3 (mg/g), respectively, accounting for approximately 38% and 39% of their measured CEC values. Column studies indicated that a metric tonne (1,000 kg) of ST-zeolite and BR-zeolite can be used to accumulatively treat 16,000 and 60,000 L of CBNG water, respectively, in order to lower the sodium adsorption ratio (SAR, mmol1/2L−1/2) of the simulated CBNG water from 30 to an acceptable level of 10. Based on the results of this study, Na+ removal with clinoptilolite zeolite appears to be a potential water treatment technology for maximizing the beneficial use of poor-quality CBNG water. Ongoing studies are evaluating water treatment techniques involving the direct application of zeolite to CBNG waters and development of a field scale prototype. [Copyright &y& Elsevier]

Abstract: Desalination of brines produced from oil and gas fields is a potential resource for potable water in the southwestern U.S. and other semi-arid areas. Oilfield brines typically contain high concentrations of Na+ and Cl−, as well as other multivalent cations and anions that can reduce efficacy of reverse osmosis (RO). RO separation of NaCl solutions at existence of other co-ions or at increased ion concentration and operating pressure was experimentally tested on a pure silicalite zeolite membrane. Water fluxes increase linearly with increase of net driving force (ΔP−Σr i RTC c,f ). Ion flux is essentially independent of the operating pressure but increases exponentially by a power factor of 1.13 as feed concentration increases from 0.001 M to 0.3 M. Inorganic cations (K+, Ca2+, and Al3+) and anions (Br−, and SO4 2−), when present in a 0.01 M NaCl solution, play an important role on separation performance of the NaCl solutions. A notable variation of water flux and ion rejection in the presence of counter cations was observed, while the permeation behavior of 0.01 M NaCl solution was hardly affected by counter anions. This study is part of a broader project seeking to make desalination of oilfield-produced waters economically viable. [Copyright &y& Elsevier]

Feasibility of the multi-effect distillation (MED) process was investigated experimentally and theoretically in present work to deal with the high-salinity organic reverse osmosis concentrates (ROCs) generated by the double membrane process for the treatment of wastewater from the refining and chemical enterprises. Two key problems involving the behaviors of organic and inorganic impurities in the ROCs during evaporation and process optimization of MED thermally and economically were highlighted. The experimental results indicated that about 6% and 8% of organic impurities volatilized during evaporation and entered into the produced water and the tail gas, respectively. The produced water and the tail gas which met the related China National standards could be reused or vented directly without further treatment. However, scaling of calcium sulfate was drastically occurred in the evaporator when about 30% water was recovered, indicating the necessity of removal of the hardness in ROCs before evaporation. A forward flow MED model established on Aspen Plus platform was employed to perform the thermal and economic analysis for the ROCs treatment. Performance analysis including the Gained Output Ratio (GOR), fresh steam flow and specific heat transfer area as functions of the effect number and the heating steam temperature were conducted. The results showed that the performance of the MED system was significantly influenced by effect number over the heating steam temperature. An increase in the effect number would improve the thermodynamic performance of MED system but increased the capital costs. The model established in this work could provide a theoretical guidance for the development of MED process dealing with ROCs. • The main valuable components and impurities in the high-salinity organic RO concentrates were analyzed and defined. • The product water and the tail gas generated by the MED process could be reused or vented directly. • Related parameters have been determined to optimize the MED process. [ABSTRACT FROM AUTHOR]

In this study, a hybrid desalination process based on carbon dioxide gas hydrate and capacitive deionization (CDI) is proposed to improve desalination performance. In this method, the formed gas hydrate crystals are dissociated and the produced water is conducted to the CDI process. To overcome the separation problem of the residual brine between hydrate crystals, a reactor that can be capable of compressing crystals was designed. Also, to improve the efficiency of the CDI process, electrodes were synthesized based on the activated carbon and their chemical properties modified using nitric acid. The performance of the gas hydrate, CDI, and hybrid desalination method examined for single and multi-salt aqueous solutions containing sodium, potassium, calcium, and magnesium with different concentrations. Also, the effects of the hydrate formation temperature, applied voltage, ion type and concentration on the ions removal efficiency have been investigated. The results showed that the compression of hydrate crystals in the hydrate desalination process, and using the modified activated carbon electrode in the CDI process could significantly improve the ions removal efficiency. The results showed that the proposed method could remove around 82% of Na+ and 100% of K+, Ca2+ and Mg2+ from saltwater with similar concentrations to seawater, respectively. • A new hybrid desalination method based on gas hydrate and CDI process has been proposed. • Compression of hydrate crystals has a significant effect on ion removal efficiency. • Ion removal efficiency in CDI process is in the following order K+ > Na+ > Ca2+ > Mg2+. • The proposed hybrid desalination method can remove 100% of K+, Ca2+, and Mg2+. [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]

Direct contact membrane distillation (DCMD) was investigated for the treatment of oil-field produced water using a hydrophobic polypropylene (PP) membrane with 0.2 μm pore size. The DCMD performance was studied under different feed temperatures ranged from 40 °C to 80 °C while the cooling temperature was maintained at 23 °C. Increasing the feed water temperature resulted in a higher permeate water flux. Stable and reliable DCMD membrane performance was observed for all used membranes. The obtained results indicated the great potential of DCMD to treat hypersaline oil-field produced water with an overall rejection of salts higher than 99.9% and that of total organic carbon (TOC) greater than 93.3%. This was due to the presence of volatile organic compounds in oil-field water. Pre-treatment of produced water using 0.45 μm filter did not show much effect on the DCMD performance. A slight gradual reduction of the permeate flux was observed due to fouling phenomenon. A simple washing the membrane with de-ionized water was found to be an effective method for cleaning the membrane and restoring the permeate flux indicating the absence of irreversible fouling. • Direct contact membrane distillation (DCMD) was investigated for the treatment of oil-field produced water. • Rejection of DCMD of hypersaline was >99.9% and 93.3% for TDS and TOC, respectively. • Feed temperature increased DCMD flux without affecting its rejection. • MCMD fouling was minimal and reversible when treating hypersaline oil-field produced water. [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]