Produced Water Treatment Research Articles

Niger Delta Oilfields Produced Water Characteristics and Treatment Technologies: Challenges and Solutions

The Nigerian Niger Delta oilfields have high water-to-oil ratio ranging from 50% to 95% water content, due to its secondary and tertiary production phases. Oil and gas producers could shut-in such wells, or develop cost effective approach for Produced Water, PW handling to meet reinjection or environmental permissibility. Thus, the study investigated the compositions and treatment techniques of Niger Delta oil and gas fields PW, and proffered solutions for actualizing minimal hazardous contaminants in PW. Characterization of PW from a Flow Station, an Oil processing and a Gas processing facilities showed biogeochemical homogeneity in the PW compositions with high organic and inorganic constituents, which are above injection and disposal specifications. The results of treated PW from the extant PW treatment (PWT) techniques showed that the total dissolved solids (TDS) concentration (6105.9 mg/l) from the Flow Station PW treatment facility did not meet the required specifications for injection into depleted wells or disposal into the environment (2,000.00 mg/l for inland, and 5,000.00 mg/l for nearshore). The salinity contents in the treated PW from the three PWT configurations were 2411.0 mg/l, 2218.6 mg/l, and 2165.4 mg/l, respectively, which were slightly above Nigerian Upstream Petroleum Regulatory Commission (NUPRC) specification (2000.0 mg/l) for nearshore disposal. The chemical oxygen demand (COD) concentration in the treated PW from the three PWT configurations were 153.0 mg/l, 148.1 mg/l, and 141.2 mg/l, respectively, which were above the NUPRC standard (125.0 mg/l). The oil and grease (O&G) concentration in the treated PW were 84.7 mg/l, 51.5 mg/l, and 58.0 mg/l, respectively, which also were above regulatory stipulation (30.0 mg/l) for nearshore disposal. The modular Bio-Unit + Ultra/Nanofiltration achieved more than 95% removal of both organic and inorganic constituents in the PW. Therefore, this study suggests that reconfiguring the extant PW treatment equipment with this cost-effective innovation would be the solution to PW treatment challenges in the Niger Delta oil and gas operations.

Manufacture and performance assessment of PVDF-La@TiO2 Photocatalyst implanted membrane for efficient produced water treatment via ozonation-adsorption process under visible-light exposure

This research aims to develop a visible light-activated photocatalytic membranes for produced water treatment system by employing the phase inversion technique for implantation of La@TiO2 photocatalytic nanoparticles into PVDF membrane at concentrations varying from 0 % to 2 % wt. The results demonstrated significant amplification of COD and NH3-N removal efficiency. Implantation of the photocatalyst into PVDF membranes via bulk mixing, coupled with elemental doping and combination with La@TiO2 appreciably reduces band gap energy and increases visible light absorption thereby improves membrane's optical properties. SEM-EDX analysis confirms uniform distribution of La@TiO2 nanoparticles on the membrane surface, which leads to amplify membrane's hydrophilicity and water absorption. The modified membrane facilitated concurrent photocatalytic degradation and filtration processes that lead to remarkable reductions in TDS, COD, and NH3-N pollutants, with the highest flux was achieved when 1.5 % wt. La@TiO2 was incorporated into the membrane matrix. Obviously, adsorption and ozonation processes promote synergistic effect and amplify pollutant flux and efficiency to a greater extent. Furthermore, the modified membrane exhibited extraordinary antifouling properties and stability, providing excellent reusability with a 96.22 % fouling reduction rate after five consecutive cycle tests.

A Mini Review on the Opportunities for Membrane Pervaporation Technology for Energy-efficient Removal of Dispersed Oil and Dissolved Hydrocarbons from Produced Water

Produced water is reported to have the largest volume of waste stream associated with hydrocarbon recovery. It was estimated to increase from 250 million B/D in 2007 to more than 300 million B/D between 2010 and 2012. Market research conducted by Adroit put the globally produced water treatment market at a value of USD 5.10 billion in 2022. This value is anticipated to be USD 9.80 billion in 2032 at a compound annual growth rate (CAGR) of 5.80% over the prediction period. Oil and gas companies have been mandated to comply with the newly enacted environmental regulations that require extensive treatment of this water before discharge or reuse. The limited quantity of freshwater resources coupled with the increasing oil and gas production activities has made it necessary for all stakeholders to look for sustainable management of this water. Presently, a certain percentage of produced water is reused while the rest is discharged into the ocean. In both cases, the water needs to be thoroughly treated. The choice of technologies for produced water treatment depends on numerous factors, such as the chemical composition of the water and the level of purity that must be attained before disposal, recycling, or re-use. Some of the technologies used for produced water treatment include physical separation methods such as gravity, adsorption, filtration, coalescence, cyclones, flotation, centrifuges, membranes, and oxidation. There are also chemical and biological separation methods. Contaminants such as small droplets of dispersed oil and dissolved hydrocarbons (DODHs) are very challenging to remove using the above-listed water treatment technologies. Moreover, the use of membrane technology has been limited only to the use of reverse osmosis and membrane filtration for removing salinity, metals, and other inorganics. This article highlights the opportunities for the use of membrane vapor permeation and pervaporation for the removal of the small droplets of DODHs, which have been reported to be very challenging contaminants to remove. The use of 3D printing technology for the fabrication of membrane materials was reviewed. The 3D membrane development method can be used to fabricate almost any shape of the material in a highly customized manner using computer-aided design. The information presented in this article will serve as a useful reference for the technologies used for a sustainable water treatment strategy in the oil and gas industry.

Fertilizer-driven FO and MD integrated process for shale gas produced water treatment: Draw solution evaluation and PAC enhancement

It is a great challenge for effective treatment of shale gas produced water (SGPW), a typical industrial wastewater with complex composition. Single forward osmosis (FO) or membrane distillation (MD) process has been widely used for desalination of SGPW, with membrane fouling not well addressed. Fertilizer draw solution (DS) with high osmotic pressure is less likely to cause FO fouling and can be used for irrigation. An integrated process using fertilizer-driven FO (FDFO) and MD process was proposed for the first time for SGPW treatment, and characteristics of fertilizer DS and powdered activated carbon (PAC) enhancement were assessed. The DS using KCl and (NH4)2SO4 had high MD fluxes (36.8–38.8 L/(m2·h)) and low permeate conductivity (below 50 μS/cm), increasing the contact angle of the MD membrane by 113 % than that without FO, while the DS using MgCl2 and NH4H2PO4 produced a lower reverse salt flux (0.9–3.2 g/(m2·h)). When diluted DS was treated using PAC, the MD permeate conductivity was further reduced to 35 μS/cm without ammonia, and the membrane hydrophobicity was maintained to 71–83 % of the original. The mechanism of the FDFO-MD integrated process for mitigating MD fouling and improving permeate quality was analyzed, providing guidance for efficient SGPW treatment.

Comments: Celebrating a Legacy: 100 Years of Innovation and 75 Years of JPT at the 2024 ATCE

_ Are you ready to join us for SPE’s Annual Technical Conference and Exhibition (ATCE) in New Orleans, 23–25 September? As SPE celebrates a century of innovation at the 2024 ATCE, we also mark the 75th anniversary of the Journal of Petroleum Technology (JPT). These twin milestones stand as a testament to the achievements that have driven our field forward—innovation, pushing boundaries, setting new standards, and fueling the energy that powers the world. Through the highs of technological breakthroughs and the lows of economic challenges, the oil and gas industry—and ATCE and JPT—have continually evolved, proving their resilience and adaptability. When considering the innovations in our industry, key advancements that often stand out include hydraulic fracturing, horizontal drilling, deepwater exploration, enhanced oil recovery, digitalization and automation, LNG technology, FPSOs, subsea systems, and decarbonization and emissions mitigation. However, the incremental steps that collectively contributed to the broadly defined “wow” factors above are equally notable. To mention only a sampling: enhanced drill-bit designs, advancements in onshore and offshore drilling rigs, real-time data collection, development of 4D seismic technology, integration of multiple data types (e.g., seismic, well logs, production data) for more-comprehensive reservoir characterization, materials-science advancements (polymers, nanocoatings), development of blowout preventers, improved leak-detection systems, and advancements in produced-water treatment and recycling technologies. Less often recognized are the failures that were essential prerequisites for eventual success. The "fail fast, fail often" approach allowed for rapid feedback and necessary adjustments, though it also contributed to the downfall of some startups over the years. As individuals, embracing failure and viewing it as a stepping stone to success is not always our natural response. Presentations at industry events on "lessons learned" vary in transparency, often influenced by differing definitions of failure, stakeholder sensitivities, and legal considerations. As a result, many of the hard knocks that paved the way for the industry's "wow" factors remain largely unknown. ATCE’s theme, “Powering the Future of Energy with a Century of Innovation,” honors the legacy of past breakthroughs while celebrating their ongoing role in shaping a resilient and sustainable future. Olivier Houzé will be named 2025 SPE President with the official passing of the baton from 2024 President Terry Palisch at ATCE. In this issue of JPT, Houzé shares his insights on the challenges facing our Society and its members in his inaugural vodcast and column, “A Roadmap for a Very Busy Year.” Visit the SPE Pavilion (Booth 1449) in the exhibition hall for a variety of SPE Pavilion Talks, including the JPT editors on Tuesday, 24 September, at 1:30 p.m. We’ll highlight the milestones of JPT’s coverage over 75 years and their significance for the future. Visit JPT to learn more about our commemorative features written to date about topics ranging from the Kurdistan Region of Iraq, Azerbaijan, the HSE journey, data science, artificial lift, and a closer look at the past 25 years of innovations in fracturing, drilling, and reservoir engineering. New This Year at ATCE - Strategic Panels will offer a platform for panelists to discuss the current and future challenges and opportunities facing the energy industry. - As an SPE member, you get a complimentary pass to the exhibition hall. If you are not a member yet, you can join now. This pass does not include access to the technical program or conference proceedings. Learn more about the free access pass here. - Non-members registered at the full conference rate will receive a post-show email with a complimentary 1-year SPE membership offer. This offer is valid for new members only, and individuals must meet membership qualifications to join. Whether you’re a seasoned professional or new to the field, ATCE offers an opportunity to connect, learn, and share. Here's to a century of ingenuity and three-quarters of a century of chronicling the journey!

Gravity-driven membrane integrated with membrane distillation for efficient shale gas produced water treatment

Substantial volumes of hazardous shale gas produced water (SGPW) generated in unconventional natural gas exploration. Membrane distillation (MD) is a promising approach for SGPW desalination, while membrane fouling, wetting, and permeate deterioration restrict MD application. The integration of gravity-driven membrane (GDM) with MD process was proposed to improve MD performance, and different pretreatment methods (i.e., oxidation, coagulation, and granular filtration) were systematically investigated. Results showed that pretreatment released GDM fouling and improved permeate quality by enrich certain microbes’ community (e.g., Proteobacteria and Nitrosomonadaceae), greatly ensured the efficient desalination of MD. Pretreatment greatly influences GDM fouling layer morphology, leading to different flux performance. Thick/rough/hydrophilic fouling layer formed after coagulation, and thin/loose fouling layer formed after silica sand filtration improved GDM flux by 2.92 and 1.9 times, respectively. Moreover, the beneficial utilization of adsorption-biodegradation effects significantly enhanced GDM permeate quality. 100 % of ammonia and 53.99 % of UV254 were efficiently removed after zeolite filtration-GDM and granular activated carbon filtration-GDM, respectively. Compared to the surged conductivity (41.29 μS/cm) and severe flux decline (>82 %) under water recovery rate of 75 % observed in single MD for SGPW treatment, GDM economically controlled permeate conductivity (1.39-19.9 μS/cm) and MD fouling (flux decline=8.3 %-27.5 %). Exploring the mechanisms, the GDM-MD process has similarity with Janus MD membrane in SGPW treatment, significantly reduced MD fouling and wetting.

Modelling and predicting lift force and trans-membrane pressure using linear, KNN, ANN and response surface models during the separation of oil drops from produced water

This study aims to improve the efficiency and reliability of membrane filtration systems used to treat produced water by accurately predicting lift force, transmembrane pressure (TMP), and total resistance (TR) using ML models, namely linear, K-nearest neighbors (KNN), and artificial neural networks (ANN). The dataset was split into training, validation, and test sets, allowing for comprehensive training and evaluation of model performance. Linear, KNN and ANN models achieved high R-squared scores (R2) of 0.998, 0.996, and 0.999 and low mean squared error (MSE) values of 0.0000046, 0.0002763, and 0.000004621 for Lift force prediction, respectively. For TMP prediction, these models showed R2 values of 0.801, 0.90, and 0.72 and MSE values of 0.01236, 0.109, and 0.283, respectively. Similarly, these models predicted TR with R2 scores of 0.76, 0.78, and 0.78 and MSE values of 0.2087, 0.025, and 0.22, respectively. These results indicate that KNN is particularly efficient in accurately predicting the membrane parameters and could be a robust tool to optimize membrane filtration processes. Response surface modelling (RSM) elucidates the relationship between input and output parameters. Initially, the increase in drop size and shear has a minimal impact on the lift force. Beyond a drop size of 0.3 μm and shear rate 1200 S−1, lift force rises significantly. TMP initially increases with shear rate, peaking at a value of 1200 S−1, then decreases with higher shear rates. Optimal conditions identified are higher shear rates and drop sizes >0.3 μm to maintain lower TMP and effective filtration. Findings from the study suggest that employing predictive modelling can significantly enhance the efficiency and reliability of produced water treatment, by improving contaminant removal, reducing energy consumption and cost, potentially reducing environmental impacts, and improving sustainability in the oil and gas industry.

Benchmarking produced water treatment strategies for non-toxic effluents: Integrating thermal distillation with granular activated carbon and zeolite post-treatment

The management of produced water (PW) generated during oil and gas operations requires effective treatment and comprehensive chemical and toxicological assessment to reduce the environmental risks associated with reuse or discharge. This study evaluated a treatment train that included a low-temperature thermal distillation pilot system followed by granular activated carbon (GAC) and zeolite post-treatment for processing hypersaline Permian Basin PW. Our study provides a unique and comprehensive assessment of the treatment efficiency considering a targeted chemical scheme together with whole effluent toxicity (WET) tests across four trophic levels regarding aquatic critical receptors of concern (ROC): Raphidocelis subcapitata, Vibrio fischeri, Ceriodaphnia dubia, and Danio rerio. The distillate from the thermal distillation process met various numeric discharge standards for salinity and major ions. However, it did not meet toxicity requirements established by the United States National Pollutant Discharge Elimination System program. Subsequent post-treatment using GAC and zeolite reduced the concentration of potential stressors, including volatile organics, NH3, Cd, Cr, Zn, and Mn in the final effluent to below detection limits. This resulted in a consistent toxicity reduction across all WET tests, with no observable adverse effects for R. subcapitata, C. dubia, and D. rerio (no observed effect concentration >100%), and V. fischeri effects reduced to 19%. This study realizes the feasibility of treating PW to non-toxic levels and meeting reuse and discharge requirements. It underscores the importance of implementing integrated treatment trains to remove the contaminants of concern and provides a systematic decision framework to predict and monitor environmental risks associated with PW reuse.

Reducing oil and grease on-site in real offshore oilfield-produced water through feasible adsorption-desorption cycling

Although produced water treatment is witnessing an increasing demand worldwide, conventional treatments are limited, marginally aiming at water-soluble pollutants. Here, we develop a cycling adsorption process, targeting water-soluble compounds and mapping the conditions to yield oils and grease content in real water matrix below the legislation requirements, allowing full adsorbent reuse through a feasible offshore route. The adsorption performance was evaluated in terms of pH, adsorbent concentration, and contact time, while the desorption performance was assessed in terms of eluent type, concentration, and contact time. The polymeric resin MN 202 presents an excellent ability to remove oil and grease from the real produced water matrix, and acid pHs favored the process. The adsorption equilibrium is reached after 12 h, with an oil and grease removal of 92 % at pH 5, presenting multilayer adsorption during the process, with an influence of external diffusion governed by hydrophobic and electrostatic interactions. In the desorption process, CH3O− species, originated by NaOH's solubilization in methanol, enables complete adsorbent regeneration in 2 h. The adsorption-desorption cycling is stable, and the adsorbent microstructure assessment indicates no significant changes in the resin surface due to adsorption-desorption runs.

Au-TiO2 nanoparticles enabled catalytic treatment of oil and gas produced water in slurry and vacuum membrane distillation systems

Produced water (PW) treatment and reuse provide a promising alternative to address freshwater scarcity and reduce the environmental impacts associated with PW disposal. Efficient treatment of PW is challenging due to its complex matrix and hypersalinity. This study developed innovative gold-doped titania (Au-TiO2) nanoparticles to enable effective treatment of PW collected from the Permian Basin with salinity of ∼118 g/L. The mechanisms of removing organics and ammonia in PW in slurry and vacuum membrane distillation (VMD) systems were investigated via thermocatalysis, photocatalysis, and photo-thermocatalysis. Photocatalysis and photo-thermocatalysis were found more effective for organic removal than thermocatalysis. A baseline study using glucose as a representative of easily degradable organic carbon showed that thermocatalysis and photocatalysis mineralized 23.2 % and 93.1 % glucose, respectively. However, photo-thermocatalysis and thermocatalysis degraded only 17.4 % and 7.5 % dissolved organic carbon (DOC), and 56.2 % and 49.2 % NH3-N in PW, respectively. Au-TiO2 coating on ceramic membranes improved the distillate flux of photo-thermocatalytic membrane distillation (PMD) compared to no catalysts coating in VMD (7.14 versus 6.75 kg per hour per m2). Both PMD and VMD rejected >99.9 % of salts and >96 % DOC, and PMD had slightly higher DOC and salt removal rates. In contrast, normalized permeate flux using pristine membranes (hydrophobically modified without catalysts coating) decreased to zero after 29 h of operation while normalized flux with TiO2-coated membranes under UV on and UV off were 57.5 % and 53.7 % on average, which is much lower than that with Au-TiO2 coated membranes in both UV on (91.3 %) and UV off (88.1 %) cases, indicating Au-TiO2 coating significantly improved membrane anti-fouling propensity and durability during treatment of complex PW. Targeted analysis of three groups of petroleum hydrocarbons and 70 volatile organic compounds showed that only 2-butanone and acetone were detected in the distillates with removal efficiencies of 80 % for 2-butanone in both PMD and VMD, and acetone was removed by 75.4 % in PMD and 69.2 % in VMD. Au-TiO2 nanoparticles demonstrated excellent catalytic performance for PW treatment in slurry and immobilized PMD systems.

Impact of surfactants used in oil and gas extraction on produced water treatment by membrane distillation

Produced water from unconventional oil and gas reservoirs often contains non-ionic surfactants that are added to the hydraulic fracturing fluid to facilitate water release and enhance gas production. This study investigates the impact of currently used surfactants (i.e., nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs)) and proposed alternative surfactants on the performance of membrane distillation (MD) for produced water treatment. The impact of NPEOs and OPEOs on wetting of PTFE membranes was studied as a function of their concentrations and ethoxylate (EO) chain length in a lab-scale DCMD system. Additionally, alternative surfactants, including linear alcohol ethoxylates (LAEs), branched secondary alcohol ethoxylates (BAEs), and alkyl polyglycosides (APGs), were evaluated for their potential to replace NPEOs and OPEOs. Experimental results indicate that the increase in the number of EO units in NPEOs decreased their tendency to cause membrane wetting by reducing their interaction with hydrophobic surfaces. It was also observed that LAEs and APGs that are environmentally friendly alternatives did not cause membrane wetting. This study provides valuable insights into the underlying mechanisms of surfactant-membrane interactions and offers guidelines for surfactant alternatives that can potentially improve hydraulic fracturing and lower environmental concerns while facilitating the use of MD for produced water treatment and recovery.

Offshore produced water treatment by a biofilm reactor on the seabed: The effect of temperature and matrix characteristics

In many industrial processes a large amount of water with high salinity is co-produced whose treatment poses considerable challenges to the available technologies. The produced water (PW) from offshore operations is currently being discharged to sea without treatment for dissolved pollutants due to space limitations. A biofilter on the seabed adjacent to a production platform would negate all size restrictions, thus reducing the environmental impact of oil and gas production offshore. The moving bed biofilm reactor (MBBR) was investigated for PW treatment from different oilfields in the North Sea at 10 °C and 40 °C, corresponding to the sea and PW temperature, respectively. The six PW samples in study were characterized by high salinity and chemical oxygen demand with ecotoxic effects on marine algae S. pseudocostatum (0.4%<EC50<2.7%). In continuous operation over a year, MBBR achieved a stable COD removal of 64 ± 5% at 10 °C and 68 ± 8% at 40 °C. Batch experiments revealed that most dissolved compounds were removed (up to 63%) within 3 h of treatment. High temperature (40 °C) was a key parameter to achieve a faster kinetics with degradation constant rate (k) up to eight-fold faster compared to 10 °C. Alongside contaminants removal, PW toxicity was also reduced (64–89%) during MBBR at both temperatures, hot and cold. The toxicity reduction was most likely related to the elimination of dissolved organic compounds, such as phenols, naphthalenes and BTEX. The biofilm was able to handle PW with high oil in water content from unstable production, as well as high salinity. Thus, MBBR seems to be a realistic solution to treat PW with complex and variable composition by removing harmful components towards the zero harmful discharge goal.

Nickel augmented biochar for sustaining produced water treatment to decarbonize oil and gas industrial waste using anaerobic-aerobic granular cylindrical periodic discontinuous batch reactors

This study assessed the efficacy of granular cylindrical periodic discontinuous batch reactors (GC-PDBRs) for produced water (PW) treatment by employing eggshell and waste activated sludge (WAS) derived Nickel (Ni) augmented biochar. The synthesized biochar was magnetized to further enhance its contribution towards achieving carbon neutrality due to carbon negative nature, Carbon dioxide (CO2) sorption, and negative priming effects. The GC-PDBR1 and GC-PDBR2 process variables were optimized by the application of central composite design (CCD). This is to maximize the decarbonization rate. Results showed that the systems could reduce total phosphorus (TP) and chemical oxygen demand (COD) by 76–80% and 92–99%, respectively. Optimal organic matter and nutrient removals were achieved at 80% volumetric exchange ratio (VER), 5 min settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration with desirability values of 0.811 and 0.954 for GC-PDBR1 and GC-PDBR2, respectively. Employing four distinct models, the biokinetic coefficients of the GC-PDBRs treating PW were calculated. The findings indicated that First order (0.0758–0.5365) and Monod models (0.8652–0.9925) have relatively low R2 values. However, the Grau Second-order model and Modified Stover-Kincannon model have high R2 values. This shows that, the Grau Second Order and Modified Stover-Kincannon models under various VER, settling time, and MLSS circumstances, are more suited to explain the removal of pollutants in the GC-PDBRs. Microbiological evaluation demonstrated that a high VER caused notable rises in the quantity of several microorganisms. Under high biological selective pressure, GC-PDBR2 demonstrated a greater percentage of nitrogen removal via autotrophic denitrification and a greater number of nitrifying bacteria. The overgrowth of bacteria such as Actinobacteriota spp. Bacteroidota spp, Gammaproteobacteria, Desulfuromonas Mesotoga in the phylum, class, and genus, has positively impacted on granule formation and stability. Taken together, our study through the introduction of intermittent aeration GC-PDBR systems with added magnetized waste derived biochar, is an innovative approach for simultaneous aerobic sludge granulation and PW treatment, thereby providing valuable contributions in the journey toward achieving decarbonization, carbon neutrality and sustainable development goals (SDGs).

Numerical optimization of duration time for the gravitational sedimentation process of produced water in oilfield

Following water flooding, polymer flooding and alkali/surfactant/polymer (ASP) flooding have become the main measures to enhance oil recovery in mature oilfields. However, it is the fact that the development of mature oilfields has continuously entered the ultra-high water cut stage, the amount of produced water has increased year by year. The characteristics of water quality have become increasingly complex, posing challenges for green and efficient separation. Taking China's mature oilfield, Daqing Oilfield, as an example, gravitational sedimentation is a basic process for produced water treatment before filtration. The duration time has always been determined based on standardized design parameters, and the adjustment of duration time depends on experience. This paper distinguishes the characteristics of produced water, and the relationship between treatment performance and production conditions is comprehensively considered. The numerical simulation method is employed to optimize the duration time for gravitational sedimentation of produced water. For produced water with different characteristics of water flooding, polymer flooding and ASP flooding, the reasonable duration time for primary sedimentation is 5 h, 12 h and 14 h respectively, and the reasonable duration time for secondary sedimentation is 3 h, 8 h and 10 h respectively. This recommendation has been validated by experiments.

Produced water treatment by semi-continuous sequential bioreactor and microalgae photobioreactor

Produced water (PW) from oil and gas exploration adversely affects aquatic life and living organisms, necessitating treatment before discharge to meet effluent permissible limits. This study first used activated sludge to pretreat PW in a sequential batch reactor (SBR). The pretreated PW then entered a 13 L photobioreactor (PBR) containing Scenedesmus obliquus microalgae culture. Initially, 10% of the PW mixed with 90% microalgae culture in the PBR. After the exponential growth of the microalgae, an additional 25% of PW was added to the PBR without extra nutrients. This study reported the growth performance of microalgae in the PBR as well as the reduction in effluent’s total organic carbon (TOC), total dissolved solids (TDS), electrical conductivity (EC), and heavy metals content. The results demonstrated removal efficiencies of 64% for TOC, 49.8% for TDS, and 49.1% for EC. The results also showed reductions in barium, iron, and manganese in the effluent by 95, 76, and 52%, respectively.

Research on Ternary Composite Flooding Produced Water Treatment Process

This paper introduces the ternary composite drive technology and the characteristics of the technology. The characteristics of ternary composite flooding produced water were sorted out, and the characteristics of complex organic composition, poor biochemical treatment, high oil content, high suspended solids content, high viscosity and high emulsification degree were sorted out. Three ternary composite flooding produced water treatment processes were introduced. Under the condition of ensuring that the effluent meets the requirements of reinjection water, the advantages and disadvantages of the three processes are compared, and finally the third process flow is determined to be the optimal option. The process can not only effectively improve the treatment effect of ternary composite flooding produced water, but also overcome the shortcomings in the conventional process, improve the feasibility of the process and reduce the cost.

Optimization and predictive modeling of membrane based produced water treatment using machine learning models

Membrane technology has become a crucial solution for treating produced water, playing a vital role in resource recovery and environmental preservation. The use of advanced Artificial Intelligence (AI) technique such as Machine Learning (ML) has introduced an innovative approach to define and model these treatment procedures such as trans-membrane pressure (TMP) and total membrane resistance. The research focuses specifically on the utilization of Artificial Neural Network (ANN) and Extreme Gradient Boosting (XGBoost) model to improve the precision and effectiveness of produced water treatment using membrane technology. Also, the study presented explores how the Artificial Neural Network (ANN) framework excels in predictive insights and process modeling, optimizing operational parameters in membrane-based treatment setups. Furthermore, integrating the Extreme Gradient Boosting (XGBoost) model highlights its ability to enhance system performance, providing accurate predictions and better control in complex treatment processes. It presents comprehensive research of combining Artificial Neural Network (ANN) and Extreme Gradient Boosting (XGBoost) model with membrane technology for produced water treatment, emphasizing their potential to improve optimization techniques and modeling approaches, ultimately enhancing water treatment efficiency and sustainability. Both the Artificial Neural Network (ANN) and Extreme Gradient Boosting (XGBoost) models achieved an impressive R-squared (R2) scores of 0.754, and 0.97 for Transmembrane Pressure (TMP), and 0.95 and 0.81 for Total Resistance prediction respectively.

Metal cation crosslinked, partially reduced graphene oxide membranes with enhanced stability for high salinity, produced water treatment by pervaporative separation

Graphene oxide (GO)-based membranes hold significant promise for applications ranging from energy storage to protective coatings, to saline water and produced water treatment, owing to their chemical stability and unique barrier properties achieving a high selectivity for water permeation. However, unmodified GO membranes are not stable when submerged in liquid water, creating challenges with their commercial utilization in aqueous filtration and pervaporation applications. To mitigate this, we develop an approach to modify GO membranes through a combination of low temperature thermal reduction and metal cation crosslinking. We demonstrate that Zn2+–rGO and Fe3+–rGO membranes had the highest permeation flux of 8.3 ± 1.5 l m−2 h−1 and 7.0 ± 0.4 l m−2 h−1, for saline water separation, respectively, when thermally reduced after metal cross-linking; These membranes maintained a high flux of 7.5 ± 0.7 l m−2 h−1, and 5.5 ± 0.3 l m−2 h−1 for produced water separation, respectively. All the membranes had a salt rejection higher than 99%. Fe3+ crosslinked membranes presented the highest organic solute rejections for produced water of 69%. Moreover, long term pervaporation testing was done for the Zn2+–rGO membrane for 12 h, and only a minor drop of 6% in permeation flux was observed, while Zn2+–GO had a drop of 24%. Both modifiers significantly enhanced the stability with Fe3+–rGO membranes displaying the highest mechanical abrasion resistance of 95% compared to non-reduced and non-crosslinked GO. Improved stability for all samples also led to higher selectivity to water over organic contaminants and only slightly reduced water flux across the membrane.

Treatment of Produced Water from Niger Delta Oil Fields Using Selected Bio-Adsorbents

Produced water (PW) is the vast amount of water produced from subsurface during the extraction of oil and gas. PW contains heavy metals which are detrimental to the environment. The majority of PW treatment technologies, which have been in use for many years, have reportedly failed to bring some impurity and metal concentrations down to permissible disposal levels. This study was done to determine how well three locally available materials which are eggshells, groundnut shells, and sugarcane bagasse used in the treatment of PW obtained from Niger Delta oil fields. The adsorbents were ground, and sieved into sizes of 425 and 1180 microns. They were treated individually with diluted nitric acid (400mL of 0.4mol/ LHNO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;) for 24 hours to remove pigments. They were filtered, dried, and rinsed with distilled water until the pH became neutral. PW samples were analysed for heavy metals using an Atomic Absorption Spectrophotometer (AAS). The PW samples were treated with the bio-adsorbents in a batch technique. The metals analysed were As, Cu, Pb and Fe. The bioadsorbents were able to reduce the concentration of the metals to 87%, 91%, 100% and 88% respectively. Langmuir and Freundlich isotherm models were used to analyse the adsorption system. It was observed that the finer the adsorbents the better the adsorption result. 425 microns was able to produce a better result compared with 1180 microns.

Non-targeted analysis and toxicity prediction for evaluation of photocatalytic membrane distillation removing organic contaminants from hypersaline oil and gas field-produced water

Membrane distillation (MD) has received ample recognition for treating complex wastewater, including hypersaline oil and gas (O&G) produced water (PW). Rigorous water quality assessment is critical in evaluating PW treatment because PW consists of numerous contaminants beyond the targets listed in general discharge and reuse standards. This study evaluated a novel photocatalytic membrane distillation (PMD) process, with and without a UV light source, against a standard vacuum membrane distillation (VMD) process for treating PW, utilizing targeted analyses and a non-targeted chemical identification workflow coupled with toxicity predictions. PMD with UV light resulted in better removals of dissolved organic carbon, ammoniacal nitrogen, and conductivity. Targeted organic analyses identified only trace amounts of acetone and 2-butanone in distillates. According to non-targeted analysis, the number of suspects reduced from 65 in feed to 25–30 across all distillate samples. Certain physicochemical properties of compounds influenced contaminant rejection in different MD configurations. According to preliminary toxicity predictions, VMD, PMD with and without UV distillate samples, respectively contained 21, 22, and 23 suspects associated with critical toxicity concerns. Overall, non-targeted analysis together with toxicity prediction provides a competent supportive tool to assess treatment efficiency and potential impacts on public health and the environment during PW reuse.