Desalination Of Produced Water Research Articles

Effect of Chloride Salts on TBAC Semiclathrate Hydrates: Application to Produced Water Desalination

Effect of Chloride Salts on TBAC Semiclathrate Hydrates: Application to Produced Water Desalination

Room-temperature ionic liquids as candidate materials for produced water desalination: Experiments and molecular dynamic analysis

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][Tf2N] 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.

Optimization-based technoeconomic comparison of multi-stage membrane distillation configurations for hypersaline produced water desalination

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 $/m3feed treatment cost, followed by VMD, CGMD, DCMD, and PGMD with 3.8, 4.2, 5.4, and 9.06 $/m3feed treatment costs corresponding to twelve, eight, eight, and sixteen stages, respectively.

Optimization of mobile oil and gas produced water treatment unit deployment logistics to achieve economic feasibility

• Techno-economic assessment of on-site produced water desalination . • The concept of capacity factor is applied to desalination where demand is variable. • Systems level optimization of mobile desalination module deployment. • Multi-objective optimization considering economics and water reclamation . Development of unconventional oil and gas wells has resulted in large volumes of wastewater that require careful handling to minimize environmental risks. Common practice is to truck the wastewater from well sites to Environmental Protection Agency Class II underground injection control wells. Recently, on-site wastewater treatment followed by surface water discharge for downstream reuse has emerged as being viable. This work applies the concept of capacity factor to on-site oil and gas wastewater treatment. By accounting for intermittent wastewater treatment demands at individual well sites, the attributes of optimal on-site packaged treatment unit deployment logistics for oil and gas wastewater management are determined. The attributes considered are packaged unit capacity, deployment length, and the number of units deployed. This work explores different deployment logistics in Weld County, Colorado, United States to determine a set of Pareto optimal logistics from a techno-economic and environmental perspective. Ultimately, there exists a Pareto frontier because the marginal cost of water treatment increases as reuse increases beyond a critical threshold, in Weld County where the cost of business as usual operation (injection) is constant at $7.68 per m 3 produced. Generally, optimal deployment logistics, when accounting for capacity factor, utilize packaged wastewater treatment units sized at 100 m 3 per day capacity with deployment location reevaluated monthly. This article focuses on the importance of capacity factors at on-site treatment units and presents limitations of the study and the opportunity for the application of the presented methods to other case studies through utilization of the open-source model produced in this work.

Immobilized Algae for Produced Water Treatment and Desalination

Produced water (PW) is the effluent generated during oil mining and extraction. On average, for every barrel of oil, 4-5 barrels of PW are generated worldwide. The presence of various contaminants in PW makes it toxic. Disposal of untreated PW into oceans and water bodies can cause adverse effects on human health and the environment. Taking into account the large volumes of it being generated, and its effects on the environment, proper treatment is required before reuse or disposal. Microalgal treatment is an effective method for the bioremediation and biodesalination of produced water when acclimatized algal biomass is used for the treatment. However, harvesting this acclimatized high-value algal biomass for reuse and recycling, and the reuse or disposal of produced water is challenging. Thus, the immobilization of microalgae into polymer matrices will be beneficial in solving both problems. Different polymers, both natural and synthetic are used as matrices for immobilizing cells. In this study, experiments were done with alginate and chitosan matrices to immobilize algae. Microalgae enriched and grown in wastewater were acclimatized to three different produced water samples by progressive adaptation in a steadily increasing ratio of produced water. The algae which could adapt and grow in the highest ratio in minimum time were immobilized and used for bioremediation of produced water. The study also evaluated the stability of the matrix in produced water and the treatment efficiency. The results of the study led to the conclusion that produced water is highly toxic for the stability of alginate and chitosan matrices. A more stable matrix has to be determined and experimented with for immobilizing algae and treatment of produced water.

Forward osmosis performance in extracting water from produced water

Produced water (PW) is a prominent brine waste in the petroleum industry, which can be reused after desalination. In this work, the influence of PW salinity variation and its composition on PW desalination through the forward osmosis process, using cellulose triacetate membrane, was investigated. In the absence of oil, increasing feed salinity from 10 to 20 g/L causes water flux to decrease from 9.43 to 7.33 LM.H. By adding 750 mg/L oil to the feed solutions with different compositions, the resulted water fluxes were almost the same and were around 7.5 LMH. The membrane fouling investigation in long-period operation (5000 min) showed a decrease of 37% in water flux. It was observed that osmotic backwashing, conducted by using 0.5 and 2 M NaCl, and chemical cleaning, treated by sodium dodecyl sulfate solution, recovered the water flux to 75% and 85% of the initial fluxes, respectively.

Nanofiltration membrane with substrate incorporated amine-functionalized graphene oxide for enhanced petrochemical wastewater and shale gas produced water desalination

Polyamide (PA) nanofiltration (NF) membranes were fabricated via interfacial polymerization (IP) with graphene oxide (GO)/aminated GO (NGO)-incorporated substrate and then compared for petrochemical wastewater and shale gas produced water desalination. Crosslinking degree of PA layer with GO-incorporated substrate and NGO-incorporated substrate was higher than pristine membrane. Water flux of TFCGO-0.05 (with GO addition mass of 0.05 wt%) and TFCNGO-0.075 (with NGO addition mass of 0.075 wt%) membrane substantially increased by 15.6% and 26.9% with the highest flux of 44.93 and 49.30 L m-2 h-1, respectively, while slight difference was observed for Na2SO4, MgSO4, NaCl rejection. The better performance of TFCNGO than TFCGO was attributed to much thinner PA layer due to relatively larger pore size, higher hydrophilicity, and possible reaction of amino group of NGOs with TMC, which resulted in lower PA layer thickness of TFCNGO membranes. Substantial enhancement of water flux (higher than 24.8%) and similar divalent ion rejections can be observed for petrochemical wastewater, as consistent with the single salt test. However, better performance in permeability and divalent ion rejections (approximately 6% higher than pristine membrane) was observed for shale gas produced water. These results also demonstrated that it is feasible to incorporate NGO into substrate for NF fabrication to improve performance for industrial water desalination.

Comments on Effect of Salts on TBAB Semi Clathrate Hydrate Formation: Application to Produced Water Desalination

In the paper titled “Effect of Salts on TBAB Semi Clathrate Hydrate Formation: Application to Produced Water Desalination” by Aziz Alhejaili, Ponnivalavan Babu, and Nagu Daraboina [Energy Fuels 2020, 34 (10), 12810–12821, DOI: 10.1021/acs.energyfuels.0c02091], the authors emphasized the possibility of tetra-n-butylammonium bromide (TBAB) semiclathrate hydrate desalination and concluded that TBAB hydrate formation is a favorable means of desalination in comparison to ice, suggesting the thermodynamic effectiveness of TBAB as a hydrate former. However, there is some incorrect and missing points, which led to the wrong analysis. The possible effect of other co-existing anions to form different semiclathrates was not considered.

Response to Comments on Effect of Salts on TBAB Semi Clathrate Hydrate Formation: Application to Produced Water Desalination

The focus of our original paper was mainly on the thermodynamic equilibrium of semiclathrate hydrate formation in the presence of salts that are common in produced water. We concluded that “TBAB hydrate formation is highly favorable in comparison with ice, suggesting the thermodynamic effectiveness of using TBAB as a hydrate former for hydrate based desalination”. Lee and Kang claim that the paper has “some incorrect and missing points, which led to the wrong analysis”. We disagree with the comments, because they are based on a misinterpretation of our objectives and analysis. However, we do agree that we should have provided more information on our analysis in the original paper. In our response, we focused on addressing these comments in detail.

Energy Analysis of Methane-Hydrate-Based Produced Water Desalination

Managing produced water (PW) is one of the significant environmental issues pertaining to the energy industry. The PW needs to be treated to meet environmental regulations and can be reused for irr...

Produced Water Desalination via Pervaporative Distillation

Herein, we report on the performance of a hybrid organic-ceramic hydrophilic pervaporation membrane applied in a vacuum membrane distillation operating mode to desalinate laboratory prepared saline waters and a hypersaline water modeled after a real oil and gas produced water. The rational for performing “pervaporative distillation” is that highly contaminated waters like produced water, reverse osmosis concentrates and industrial have high potential to foul and scale membranes, and for traditional porous membrane distillation membranes they can suffer pore-wetting and complete salt passage. In most of these processes, the hard to treat feed water is commonly softened and filtered prior to a desalination process. This study evaluates pervaporative distillation performance treating: (1) NaCl solutions from 10 to 240 g/L at crossflow Reynolds numbers from 300 to 4800 and feed-temperatures from 60 to 85 °C and (2) a real produced water composition chemically softened to reduce its high-scale forming mineral content. The pervaporative distillation process proved highly-effective at desalting all feed streams, consistently delivering <10 mg/L of dissolved solids in product water under all operating condition tested with reasonably high permeate fluxes (up to 23 LMH) at optimized operating conditions.

Effect of Salts on TBAB Semi Clathrate Hydrate Formation: Application to Produced Water Desalination

Produced water (PW) is the water associated with crude oil production. It presents a huge environmental and economic problem in the oil and gas industry. Currently, the landfill is the primary disp...

Integrated membrane system without adding chemicals for produced water desalination towards zero liquid discharge

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.

Techno-Economic Analysis of RO Desalination of Produced Water for Beneficial Reuse in California

There is approximately 508.7 million cubic meters (3.2 million barrels) of oilfield-produced water generated per year across the oil fields of California. While less than 2% of this produced water receives advanced treatment for beneficial reuse, changing regulations and increasing scarcity of freshwater resources is expected to increase the demand for beneficial reuse. This paper reviews onshore-produced water quality across California, relevant standards and treatment objectives for beneficial reuse, identifies contaminants of concern, and treatment process design considerations. Lastly, we evaluate the capital and operating costs of an integrated membrane system for treating produced water based on data from a field pilot conducted in the coastal region of California.

Performance evaluation of the different nano-enhanced polysulfone membranes via membrane distillation for produced water desalination in Sert Basin-Libya

A Polysulfone-Polyethylene glycol (PS/PEG) flat sheet membrane was prepared by phase inversion technique. Dimethyl Formamide (DMF) was utilized as a solvent and deionized water was utilized as the coagulant. Polyethylene glycol (PEG) of a various dose of PEG 2000 was utilized as the polymeric improvers and as a pore-forming agent in the casting mixture. The single-walled carbon nanotube (SWCNTs), multi-walled carbon nanotube (MWCNTs), aluminum oxide (Al2O3) and copper oxide (CuO) nanoparticles (NPs) were utilized to improve the PS/PEG membrane performances. The characterizations of the neat PS, PS/PEG, PS/PEG/Al2O3 (M1) PS-PEG/CuO (M2), PS-PEG/SWCNTs (M3) and PS/PEG/MWCNTs (M14) nanocomposite (NC) modified membranes were acquired via Fourier-transform infrared analysis (FTIR), water contact angle estimation (WCA), scanning electron microscope (SEM), dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA). Enhanced Direct contact membrane distillation (EDCMD) unit was used for estimating the efficiency of the performance of the synthesized NC membranes via 60 °C feed synthetic water and/or saline oil field produced water samples containing salinities 123,14 mg/L. Adjusting the operational procedures and water characteristics confirmed a high salt rejection of 99.99% by the synthesized NC membranes. The maximum permeate flux achieved in the order of SWCNTs (20.91) > Al2O3 (19.92) > CuO (18.92) > MWCNT (18.20) (L/m2.h) with adjusted concentration of 0.5, 0.75, 0.75, 0.1 wt% compared with PS weight, i.e. 16%. The optimum operational circumstances comprised feed and permeate temperatures 60 °C and 20 °C, respectively. The achieved flux was 5.97 L/m2.h, using brine oil field produced water, via PS/PEG/SWCNTs membrane with 0.5 wt% of SWCNTs. Moreover, the membrane indicated sustaining performance stability in the 480 min continuous desalination testing, showing that the synthesized PS/PEG/SWCNTs NC modified membrane may be of magnificent potential to be activated in EDCMD procedure for water desalination.

Novel Janus composite hollow fiber membrane-based direct contact membrane distillation (DCMD) process for produced water desalination

In this study, an innovative Janus composite hollow fiber membrane-based direct contact membrane distillation (DCMD) process was boosted for desalination of actual produced water with elevated total dissolved solids (TDS) of 154,220 mg/L. The Janus composite hollow fiber membrane (Janus-HFM) was characterized with a thin and hydrophobic polyvinylidene difluoride (PVDF) and superhydrophobic silica nanoparticles (Si-R) outer layer, and a thick porous and hydrophilic PVDF and polyethylene glycol (PEG) inner layer. Compared to the neat PVDF hollow fiber membrane, the Janus-HFM showed both increased permeate water flux and improved energy efficiency with more than 99.99% salt rejection. The long-term desalination performance of the Janus-HFM was investigated via 200 h of continuous DCMD experiment. The results showed that the permeate water flux declined from 25.41 kg/m2h to 15.21 kg/m2h, and the salt rejection was 98.4% at the end of the operation. It was found that both scales and dissolved organic matters induced foulants accumulated at the feed side of the membrane due to the complex composition of the produced water. Nonetheless, the desalination performance decline can be effectively inhibited from 40% to 9.7% with a simple physical cleaning process by using the permeate water that recovered in the DCMD process.

Integrated Ejector‐Based Flare Gas Recovery and On‐Site Desalination of Produced Water in Shale Gas Production

AbstractFlaring is a major concern in the oil and gas industry as it wastes valuable raw materials/energy and emits a substantial amount of air pollutants. The produced water treatment during oil and gas production is very troublesome due to its large processing volume, high salinity, and expensive disposal cost. Thus, the on‐site integration of the flaring gas recovery (FGR) and desalination processes for handling the produced water could not only monetize flare emission sources but could also generate freshwater for versatile usages. Here, a novel process was developed integrating the ejector‐based FGR (EFGR) process with the thermal vapor compression (TVC)‐based desalination process. The newly developed EFGR‐TVC process is shown to be technically viable and cost‐effective under normal operating conditions.

Effect of gas type and salinity on performance of produced water desalination using gas hydrates

Abstract In recent years, formation of gas hydrate has been considered as a suitable method for brine water desalination. In this study, for saline produced water treatment, design of experiment with two factors, the type of gas and electrical conductivity of initial brine solution (EC0) as a measure of salinity, were applied and removal efficiencies were analyzed. For this purpose, two different hydrate formers, CO2 and natural gas (NG) were separately mixed with different produced water samples. The hydrate formation reactions were carried out at 274.2 K in 35 and 95 bar, respectively, and removal efficiencies of produced water samples were tested. It has been found that with a three-stage hydrate process, 86% of dissolved minerals can be removed by the desalination process using CO2 hydrate formation gas while this amount will be 82% when NG is applied as hydrate former. Analysis of experiments indicated that the desalting efficiency depends on the hydrate-forming gas (CO2 > NG) as well as the amount of EC0 (high EC0 > low EC0).

Agro-environmental sustainability and financial cost of reusing gasfield-produced water for agricultural irrigation

Produced water (PW) is the largest by-product generated from oil and gas extraction. Currently, half of the total PW volume is managed through environmentally-controverted and costly disposal practices. In dry regions, PW could be beneficially reused to irrigate crops reducing the overexploitation of freshwater resources. However, PW quality, and particularly its high salinity, sodicity and alkalinity, create uncertainties regarding the agro-environmental sustainability and the cost of this practice. The aim of this paper was to identify potential agro-environmentally sustainable irrigation schemes with gasfield-PW in hyper-arid Qatar and to estimate their operating costs. A soil-water model was used to simulate the irrigation of sugar beet with gasfield-PW under the climatic and soil conditions occurring in northern Qatar. Different irrigation strategies combining over-irrigation, PW blending with treated sewage effluent (TSE) and PW desalination were tested in order to protect the soil and the aquifer from salinisation and sodification. The operating costs of identified agro-environmentally sustainable scenarios were estimated through a cost analysis. In the case study, the simulations indicated that using an irrigation volume up to ∼300% of the crop water needs with a blend of two-thirds PW and one-third TSE (or desalinated PW) could preserve the soil stability, crop yield and groundwater quality. The least-cost option was to reduce the irrigation amount at a little over the crop water needs and mix PW with an equivalent volume of TSE or four equivalent volumes of desalinated PW which would cost $0.26/m3 and $0.46/m3 respectively. As traditional PW disposal practices cost between $0.06–$16.67/m3, reusing PW in irrigation is thus potentially a competitive PW management strategy for O&G firms.

Saline produced water treatment using gas hydrates

Formation of gas hydrate can be considered as a suitable method of produced water desalination. In this study, CO2 hydrate formation experiments with different produced water samples were conducted at approximately 3.5MPa and 274.2K. After hydrate formation, the concentrated salty water was extracted from the reactor and the formed hydrate was washed with a suitable amount of fresh water to improve salt removal effectively and finally hydrate was dissociated to produce fresh water. Removal efficiency for dissolved mineral components in the produced water samples was also examined. It was concluded that with a three-stage hydrate process, 82–89.2% of dissolved minerals will be excluded. This study illustrated that the CO2 hydrate −based desalination can be used for produced waters with total dissolved solids less than 160,000mg/L.