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Produced water is the interstitial reservoir water that flows to the surface with the crude oil into the production separators. This study addressed the effects of some chemicals on produced water and the challenges of finding the optimal concentrations of these chemicals for treating produced water. In this study, produced water treatment was carried out in an oil production platform located in the Niger Delta so as to determine the effect of a particular scale inhibitor, biocide, demulsifier and water clarifier, also to obtain the optimum concentrations of these chemicals in the treatment of produced water. The physico-chemical properties and microbial content of the produced water were determined. The results showed that the conductivity, hardness, pH and alkalinity reduced with increasing concentration of the scale inhibitor. The total heterotrophic bacteria count (THBC), heterotrophic fungi count (THFC) and the Sulphate reducing bacteria count (SRBC) were found to reduce with increasing concentration of biocide and exposure time. The increase in biocide concentration from 64 PPM to 100 PPM resulted in the reduction of THBC by 99.78%, THFC by 81.32% and SRBC 99.85%. The water clarifier gave the optimum concentration for oil and grease in the produced water at 7.3 PPM.

Water from gas and oil fields has a high grade of toxicity. This article shows a list of the contaminants associated with the production water from gas fields and the possible environmental impacts caused by their discarding into the ocean. Also, the different international regulations governing the discarding of production water to the sea and the technologies that have been developed for the removal of pollutants are mentioned. The results of the study show some advanced water treatment systems applied to gas fields that could reduce the environmental impact on the marine ecosystems of the Colombian Caribbean.

High-strength low-alloy steel is used in pipelines, which transport oil/gas and also produced water in the process of the secondary recovery of oil. This paper investigates the corrosion of X80 steel after immersion in static systems (biotic and abiotic). The corrosion rate, the corrosion morphology and the hardness of the coupons were investigated. The corrosion products were determined by SEM/EDS and XRD. The corrosion rates of the coupons in the biotic system were moderate and had an agressive pit morphology, while those of the coupons in the abiotic system were low with less aggressive pit. The hardness of the coupons after exposure to the systems of produced water was not changed compared with that of the control coupons. The corrosion products formed in the biotic system were Fe(OH)3, Fe(OH)2, FeOOH, Fe3O4, FeS2, FeCl3, and in the abiotic system, NaCl, CaCl2 and SrSO4. BaSO4 and CaCO3 were identified in both systems.

The main aim of this study is to investigate the technical and economic feasibility of the pulse electrocoagulation (PE) process on the treatment of oilfield alkali/surfactant/polymer flooding produced water. By using an Fe electrode, the performance of the PE process was analyzed in terms of operating parameters such as pulse duty cycle, current density, pulse frequency, electrode distance, and reaction time with removal efficiencies, some of which are presented in figures and others are given in tables due to the numbers of parameters. Under the optimal conditions of a pulse duty cycle of 0.3, current density of 35 mA/cm2, pulse frequency of 3.0 kHz, electrode distance of 1.0 cm, and reaction time of 40 min, the removal efficiencies of chemical oxygen demand (COD), oils and greases, turbidity, total suspended solids, and polyacrylamide reach 98.3, 99.0, 98.8, 98.1 and 94.3%, respectively, with an energy consumption of 0.19 kWh/kg CODremoved and an electrode consumption of 3.1 kg Fe/kg CODremoved. The quality of the final effluent could satisfy the requirement of the national discharge standard. Compared with the traditional direct current method, the PE process could save 76% of the energy. Moreover, the treatment performance of PE is much better than traditional chemical coagulation treatment using polymeric ferric sulfate.

Abstract Background Oil field produced water (OFPW) is widely produced in large volumes around the world. Transforming the organic matter in OFPW into bioenergy, such as biomethane, is one promising way to sustainability. However, OFPW is difficult to biologically degrade because it contains complex compounds such as naphthenic acids (NAs), or polycyclic aromatic hydrocarbons (PAHs). Although active microbial communities have been found in many oil reservoirs, little is known about how an exotic microbiome, e.g. the one which originates from municipal wastewater treatment plants, would evolve when incubated with OFPW. Results In this study, we harvested methanogenic biomass from two sources: a full-scale anaerobic digester (AD) treating oil and gas processing wastewater (named O&G sludge), and from a full-scale AD reactor treating multiple fractions of municipal solid wastes (named MS, short for mixed sludge). Both were incubated in replicate microcosms fed with PAHs, NAs, or OFPW. The results showed that the PAHs, NAs, and OFPW feeds could rapidly alter the methanogenic microbiomes, even after 14 days, while the O&G sludge adapted faster than the mixed sludge in all the incubations. Two rarely reported microorganisms, a hydrogenotrophic methanogen Candidatus methanoregula and a saccharolytic fermenter Kosmotoga, were found to be prevalent in the PAHs and OFPW microcosms, and are likely to play an important role in the syntrophic degradation of PAHs and OFPW, cooperating with methanogens such as Methanoregula, Methanosarcina, or Methanobacterium. Conclusions The dominant phyla varied in certain patterns during the incubations, depending on the biomass source, feed type, and variation in nutrients. The sludge that originated from the oil and gas processing wastewater treatment (O&G) reactor adapted faster than the one from municipal solid waste reactors, almost certainly because the O&G biomass had been “pre-selected” by the environment. This study reveals the importance of biomass selection for other crude oil-waste-related bioengineering studies, such as bioaugmentation and bioremediation.

This study was conducted to determine the concentrations of oil and grease in produced water from Sadqal oil and gas field in Fateh Jang, Punjab, Pakistan and their impact on surrounding soil. Produced water samples were collected from various locationsincluding inlet of pond A, pond A, inlet of pond B, pond B, outlet of pond B and external stream. Concentration of oil and grease from various locations showed that all values were higher than the permissible limit of Pakistan Environmental Protection Agency (Pak-EPA). Soil samples were collected from the same location points of the produced water. In soil samples oil and grease were found in high amounts due to continuous discharge of produced water in that area. Therefore, produced water should be treated properly before being released into the surrounding environment and Pak-EPA should have regular monitoring programs.

DNA and RNA-based sequencing of the 16S rRNA gene and transcripts were used to assess the phylogenetic diversity of microbial communities at assets experiencing corrosion in an oil production facility. The complementary methodological approach, coupled with extensive bioinformatics analysis, allowed to visualize differences between the total and potentially active communities present in several locations of the production facility. According to the results, taxa indicative for thermophiles and oil-degrading microorganisms decreased their relative abundances in the active communities, whereas sulfate reducing bacteria and methanogens had the opposite pattern. The differences in the diversity profile between total and active communities had an effect on the microbial functional capability predicted from the 16S rRNA sequences. Primarily, genes involved in methane metabolism were enriched in the RNA-based sequencing approach. Comparative analysis of microbial communities in the produced water, injection water and deposits in the pipelines showed that deposits host more individual species than other sample sources in the facility. Similarities in the number of cells and microbial profiles of active communities in biocide treated and untreated sampling locations suggested that the treatment was ineffective at controlling the growth of microbial populations with a known corrosive metabolism. Differences in the results between DNA and RNA-based profiling demonstrated that DNA results alone can lead to the underestimation of active members in the community, highlighting the importance of using a complementary approach to obtain a broad general overview not only of total and active members but also in the predicted functionality.

Goal: Industry 4.0 enables the design of new models for process monitoring in which sensors, analyzers, and controls are positioned at different points in the process. The goal of this work is to present the modeling and control of a three-phase production separator with hydrocyclones to treat produced water on an oil platform of mature fields. Design / Methodology / Approach: The Methodology or approach used was to develop a model for the primary separator that allows its operation by means of a controller (fuzzy and PI) to manipulate the flow of discarded water, acting indirectly in the oil-in-water measure. Results: The results showed the consistency of the model for open loop simulations and the effectiveness of the controllers to comply with the discarding requirements for the closed-loop simulations. Limitations of the investigation: The limitation of the model and developed controllers is that they are only applied to platforms where water production exceeds the separators discharge capacity and the exceeding water can be offloaded to another equipment or to another platform. Practical implications: The main practical implications of this study are to maximize the flow of discarded water on mature field platforms, which produces elevated amounts of water, to conform the total oil and grease to the local law regulations. Additionally, it also increases oil production, with a higher limit of water production. Originality / Value: Compared to the previous authors, where the models of discarded flow is a function of the water-oil interface, this work developed a model that allowed the flow of the discarded water to be a function of its quality.

The main purpose of this work is to investigate the pitting corrosion behavior of sigmatized duplex stainless steel (DSS) exposed to two different chloride environments: simulated seawater solution and produced water solution. Specimens taken from a commercial DSS (UNS 31803) have been subjected to aging treatments at 850°C for different holding times to achieve different amounts of sigma phase. Metallographic examinations combined with X-ray diffraction technique were employed to follow the microstructure evolution. The pitting potential of the aged samples were determined in simulated seawater solution and produced water solution. It was established that solution treated DSS shows a high pitting corrosion resistance in both test solutions, while serious deterioration of corrosion properties occurs in presence of sigma phase. It was concluded that both sigma phase amount and chloride concentration worsen the pitting potential, the higher sigma content, the lower pitting potential and the higher chloride concentration, the lower pitting potential. SEM observation showed that pitting nucleation occurs preferentially at sigma phase interfaces due to the development of Cr- and Mo-depleted regions around sigma phase. It was also confirmed that the hardness behavior is only affected for long term aged samples.

The Permian Basin, underlying southeast New Mexico and west Texas, is one of the most productive oil and gas (OG) provinces in the United States. Oil and gas production yields large volumes of wastewater with complex chemistries, and the environmental health risks posed by these OG wastewaters on sensitive desert ecosystems are poorly understood. Starting in November 2017, 39 illegal dumps, as defined by federal and state regulations, of OG wastewater were identified in southeastern New Mexico, releasing ~600,000 L of fluid onto dryland soils. To evaluate the impacts of these releases, we analyzed changes in soil geochemistry and microbial community composition by comparing soils from within OG wastewater dump-affected samples to unaffected zones. We observed significant changes in soil geochemistry for all dump-affected compared with control samples, reflecting the residual salts and hydrocarbons from the OG-wastewater release (e.g., enriched in sodium, chloride, and bromide). Microbial community structure significantly ( P < 0.01) differed between dump and control zones, with soils from dump areas having significantly ( P < 0.01) lower alpha diversity and differences in phylogenetic composition. Dump-affected soil samples showed an increase in halophilic and halotolerant taxa, including members of the Marinobacteraceae, Halomonadaceae, and Halobacteroidaceae, suggesting that the high salinity of the dumped OG wastewater was exerting a strong selective pressure on microbial community structure. Taxa with high similarity to known hydrocarbon-degrading organisms were also detected in the dump-affected soil samples. Overall, this study demonstrates the potential for OG wastewater exposure to change the geochemistry and microbial community dynamics of arid soils.IMPORTANCEThe long-term environmental health impacts resulting from releases of oil and gas (OG) wastewater, typically brines with varying compositions of ions, hydrocarbons, and other constituents, are understudied. This is especially true for sensitive desert ecosystems, where soil microbes are key primary producers and drivers of nutrient cycling. We found that releases of OG wastewater can lead to shifts in microbial community composition and function toward salt- and hydrocarbon-tolerant taxa that are not typically found in desert soils, thus altering the impacted dryland soil ecosystem. Loss of key microbial taxa, such as those that catalyze organic carbon cycling, increase arid soil fertility, promote plant health, and affect soil moisture retention, could result in cascading effects across the sensitive desert ecosystem. By characterizing environmental changes due to releases of OG wastewater to soils overlying the Permian Basin, we gain further insights into how OG wastewater may alter dryland soil microbial functions and ecosystems., Competing Interests: The authors declare no conflict of interest.

Oil and gas industries produce a huge amount of wastewater known as produced water which contains diverse contaminants including salts, dissolved organics, dispersed oils, and solids making separation and purification challenging. The chemical and thermal stability of graphene oxide (GO) membranes make them promising for use in membrane pervaporation, which may provide a more economical route to purifying this water for disposal or re-use compared to other membrane-based separation techniques. In this study, we investigate the performance and stability of GO membranes cast onto polyethersulfone (PES) supports in the separation of simulated produced water containing high salinity brackish water (30 g/L NaCl) contaminated with phenol, cresol, naphthenic acid, and an oil-in-water emulsion. The GO/PES membranes achieve water flux as high as 47.8 L m−2 h−1 for NaCl solutions for membranes operated at 60 °C, while being able to reject 99.9% of the salt and upwards of 56% of the soluble organic components. The flux for membranes tested in pure water, salt, and simulated produced water was found to decrease over 72 h of testing but only to 50–60% of the initial flux in the worst-case scenario. This drop was concurrent with an increase in contact angle and C/O ratio indicating that the GO may become partially reduced during the separation process. Additionally, a closer look at the membrane crosslinker (Zn2+) was investigated and found to hydrolyze over time to Zn(OH)2 with much of it being washed away during the long-term pervaporation.

Accurate online water quality measurements have gained attention during the last decades in the oil and gas industry for improving operational performance and protecting the surrounding environment. One potential solution to extend the reservoirs’ economic life and put less strain on the environment is by re-injecting the produced water, but the injected water quality must be high and consistent to prevent injectivity reduction. This paper evaluates two different online microscopy analyzers that utilize a high-resolution video camera for capturing images of the particles passing their view cell. The calibration procedure for both online microscopy analyzers has been thoroughly validated for steady-state and real-time measurements. The real-time measurements were achieved by post-processing the data captured by the microscopes and applying a trailing moving average window. The performance of measuring the oil-in-water concentration was compared with an online fluorescence-based monitor. The paper addresses the statistical considerations when defining the level of accuracy of the predicted particle size distribution within a defined confidence interval. Both microscopes showed promising results for measuring known particle sizes and oil-in-water concentrations, both in steady-state and real-time.

The method of hydraulic fracturing used to exploit unconventional shale gas has raised public concerns over the volumes of freshwater that are extracted for injection operations as well as the volumes of wastewater generated as a by-product of gas production. Using data from the British Columbia Oil and Gas Commission, this paper examines the volumes of produced and injected water from hydraulically fractured gas wells in Northeastern British Columbia. The two major producing shale gas basins in the province are the Montney and the Horn River. In this study, these are divided into several sub-basins based on existing geological and reservoir engineering applications. For each sub-basin the average volumes of wastewater- and injected water per well are calculated and then normalized to cumulative gas production. Ratios of injected water: gas production and wastewater: gas production are then applied to estimated volumes of remaining gas reserves in each sub-basin in order to calculate a total water footprint of future exploitation. These extrapolated water footprints were further elaborated into three scenarios of wastewater recycling rates: 0, 40, and 100% re-use. This study also compares the quality and quantity of wastewater produced from hydraulically fractured wells to their conventional counterparts in the province. Based on these calculations, the total future freshwater withdrawal and wastewater production volumes for all basins range from 1.65 to 3 billion, and 0 to 1.35 billion cubic metres, respectively. Volumes of freshwater withdrawal are relatively modest compared to other industries when considering the size of Northeastern British Columbia and the time-scale of extraction. In general, hydraulically fractured wells in Northeastern British Columbia produce volumes of wastewater that are equal to or lower than those required for injection. Unconventional gas wells often produce far less wastewater than their conventional counterparts. [ABSTRACT FROM AUTHOR]

Sample preparation has remained a bottleneck in analysis of biological and environmental samples. Thus, microextraction techniques to reduce time, cost, labor, and environmental impacts as compared to traditional solid phase or liquid-liquid extractions are appealing. In this work, a high throughput extraction method coupled with a novel desorption technique has been developed for the analysis of eight regulated PAHs in water. The targeted analytes were extracted by thin film microextraction (TFME) using single-use sorbents. The enriched analytes on thin films were directly introduced into a gas chromatography with a flame ionization detector (GC-FID) through solvothermal headspace desorption (ST-HD). The desorption of analytes was accelerated by adding a small volume of solvent into the headspace vial. The parameters that influence desorption, such as type and volume of solvent, oven temperature, and desorption time, were studied. As well, the key parameters (stirring rate, extraction time, and salt content) for TFME of PAHs from water were assessed and optimized. Reusability and durability of the film and background noise due to polymer decomposition were also assessed. The method was validated using standards in 3.5% aqueous NaCl. The limits of detection (LODs) were between 0.2 and 2.0 ng mL−1, with linear ranges of 0.4–200.0 ng mL−1 with R2 > 0.99, and satisfactory accuracy and repeatability at three concentrations (low, mid, and high) within the linear range of the calibration curves. The calibration curves were also assessed for suitability as a matched matrix in the analysis of PAHs in a seawater sample. The technique was also applied for determination of PAHs in a produced water sample without the need for pretreatment and filtration of the sample. Although the complexity of produced water required the use of standard addition, we demonstrated that this approach is a useful tool for the analysis of complicated environmental samples. Image 1 • Porous polymeric films were fabricated using an in-house method for single-use sample preparation purposes. • A high throughput extraction protocol with no preconditioning step was developed for analysis of PAHs in water samples using porous films. • Solvothermal-headspace desorption was proposed for direct introduction of adsorbed analytes into GC-FID. • The desorption from extraction phase was accelerated by small volume of solvent. • The proposed methodology was used for determination of PAHs in complex matrices such as seawater and produced water. [ABSTRACT FROM AUTHOR]

Dunaliella tertiolecta was grown in an oilfield-produced water-based medium (PW) over a wide range of salinities (30–210 g total dissolved solids (TDS) L−1). Similar biomass productivity was observed from 30 to 120 g TDS L−1 with decreased growth at the higher salinities of 180 and 210 g TDS L−1. Biomass productivity in all PW conditions was higher than in the commercial f/2 algae growth medium (35 g TDS L−1), which may have been the result of higher bicarbonate concentration of the PW (20 vs. 2 mM). In the lower salinity conditions (30 and 60 g TDS L−1), the total lipid component of biomass was highest at about 35–40% coinciding with nutrient depletion (nitrogen and phosphorus). The lipid fraction then decreased in the nutrient-depleted media as the culture added biomass. Early lipid enrichment in the 30 and 60 g TDS L−1 conditions coincided with peak pH which likely represented maximum bicarbonate uptake. The higher salinities tested (120, 180, and 210 g TDS L−1) displayed a different pattern of an increasing lipid fraction of biomass in a nutrient-depleted media until stationary phase (peak total lipid fraction approximately 31–34%). Fatty acid methyl ester profiles (FAME) at all salinities tested were dominated by C16:0 with a lesser amount of unsaturated C18 carbon chains and should produce a quality biodiesel. The characteristic of the FAME did not vary considerably by salinity. Increased biomass and lipid productivity might result from utilizing hypersaline PW with high bicarbonate concentrations (often already present) for algae cultivation. [ABSTRACT FROM AUTHOR]

This work presents analysis of breakthrough curves collected from monitoring wells located around an impoundment that leaked produced water in fractured bedrock. The analysis demonstrated that fractured bedrock flow could be highly heterogeneous, with produced water impacting some monitoring well, but not others located within the same distance as impacted wells, and within the same general alignment from the leaking impoundment. Breakthrough curves that were collected before and after the impoundment leak event contained information that was used to reconstruct events that led to the leaking of the impoundment. The breakthrough curve analysis methods presented in this work could be used in similar situations where groundwater flow is dominated by unidirectional fracture porosity. [ABSTRACT FROM AUTHOR]

In semiarid regions, water scarcity is a problem that risk the sustainability of regional socioeconomic development. The present work aimed to evaluate the quality of produced water from the oil industry in northeastern Brazil in the municipality of Mossoró - RN and its potential use in irrigation. Produced water samples were evaluated for physicochemical characterization (pH, conductivity, total dissolvedsolids, salinity, alkalinity, carbonate, bicarbonate, calcium, magnesium, hardness, chloride, sodium, potassium, nitrate, sulfate, iron) andtoxicological (metals), heavy duty: cadmium, copper, lead, chrome, manganese, nickel, zinc and aluminum in addition to TOG. Regarding the physicochemical analyzes, NaHCO3, Ca2+, Mg2+, K+ and Cl- values were outside the thresholds considered by the EMBRAPA irrigation manual. For toxicological analysis all metals were compliant and only TOG exceeded the limital lowed by CONAMA n° 430/2011 which deals with the management of effluent discharge, indicating the need to incorporate processes to eliminate and or minimize the occurrence of these compounds, since the water used in this study was an effluent, without any treatment, ensuring the sanitary safety of this resource in irrigation practices. Thus, the produced water can be considered an alternative water resource for irrigation after proper treatment. [ABSTRACT FROM AUTHOR]

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DNA and RNA-based sequencing of the 16S rRNA gene and transcripts were used to assess the phylogenetic diversity of microbial communities at assets experiencing corrosion in an oil production facility. The complementary methodological approach, coupled with extensive bioinformatics analysis, allowed to visualize differences between the total and potentially active communities present in several locations of the production facility. According to the results, taxa indicative for thermophiles and oil-degrading microorganisms decreased their relative abundances in the active communities, whereas sulfate reducing bacteria and methanogens had the opposite pattern. The differences in the diversity profile between total and active communities had an effect on the microbial functional capability predicted from the 16S rRNA sequences. Primarily, genes involved in methane metabolism were enriched in the RNA-based sequencing approach. Comparative analysis of microbial communities in the produced water, injection water and deposits in the pipelines showed that deposits host more individual species than other sample sources in the facility. Similarities in the number of cells and microbial profiles of active communities in biocide treated and untreated sampling locations suggested that the treatment was ineffective at controlling the growth of microbial populations with a known corrosive metabolism. Differences in the results between DNA and RNA-based profiling demonstrated that DNA results alone can lead to the underestimation of active members in the community, highlighting the importance of using a complementary approach to obtain a broad general overview not only of total and active members but also in the predicted functionality. [ABSTRACT FROM AUTHOR]

The Southern Junggar Basin (SJB) in China is an emerging coalbed methane (CBM) development area with abundant low-rank CBM resources. CBM development is accomplished by pumping significant volumes of water from the aquifer, and this water is commonly termed as produced water, which has great utilization values for the water-deficient areas like SJB. Geochemistry signatures are prerequisites in the management of the produced water. Meanwhile, geochemistry surveys of this produced water could also help study the basin hydrogeology and then serve the CBM development. In this study, geochemical compositions of the produced waters, including major ions, stable isotopic compositions, trace elements, and rare earth elements, were analyzed. Results show that produced waters from CBM wells in the SJB are of Na-HCO3 type and have wide total dissolved solid (TDS) ranges from 963 to 11,916 mg/L (avg. 7417 mg/L). Cl−, Na+, and HCO3− are the principal determinates of the TDS contents of the produced waters, and their concentrations all increase with greater depth of the produced waters. Overall, the net results of groundwater−aquifer mineral−bacteria interactions with groundwater flowing along the flow path are to deplete Ca2+, Mg2+, and SO42− and increase Na+, Cl−, HCO3−, and TDS. Stable isotopic values of the CBM produced waters (δDH2O and δ18OH2O) cluster along or below the local meteoric water line (LMWL), and the shift of stable isotopic values to the right side of LMWL was affected by a joint effect of evaporation and mixing with near-surface water. Trace elements that exceed the regulated concentrations for drinking water of China include As, Fe, Mn, Ba, and Ni, among which Ba and Fe need to be most concerned because over 50% of the CBM produced waters exceed the regulated values. Through principal component analysis, the trace element associations in the CBM produced waters and their potential origins were analyzed. The ∑REY concentrations of the CBM produced waters increase exponentially with the increase of pH and present a certain correlation with TDS. The relationship between ∑REY concentrations and TDS reflects different water–rock reaction degrees and hydrogeological backgrounds. [ABSTRACT FROM AUTHOR]

BACKGROUND: Greywater and produced water are undoubtedly valuable resources for reclaimed water, which can lessen the burden on use of freshwater. However, most often the membrane technology used for treatment of greywater and produced water suffers massively from fouling‐related issues. In the present study, a novel and facile method is successfully developed for modification of polypropylene (PP) microfiltration (MF) membrane via surface coating with sericin for imparting better antifouling properties. RESULT: The membrane hydrophilicity significantly improved after sericin coating and exhibited high water content (64.87%) and low water contact angle (38°). In a comparative study with synthetic greywater, the sericin‐coated membrane removed <90% turbidity and produced a greater volume of purified water with 15% less fouling compared to the uncoated membrane. The fouling experiment concludes that the sericin‐coated membrane can reduce reversible and irreversible fouling by ≈30% and ≈83.00%, respectively, relative to the uncoated membrane using pure water backwash operation. In the second case, the sericin‐coated membrane was able to provide consistent permeate quality with produced water: chemical oxygen demand <43 ppm, biological oxygen demand <6.8 ppm, suspended solids completely removed, total dissolved solids <112 ppm, turbidity <5 NTU and oil content <0.044 ppm, together with 10.5% less fouling than uncoated membrane. CONCLUSION: This study reveals that sericin coating enhanced membrane hydrophilicity and hence exhibited better antifouling properties. The sericin‐coated MF membrane effectively treated greywater as well as produced water with less fouling and within limits of national standards for reusability. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes and their magnetite derivatives were employed as adsorbents for emulsified oil removal from produced water. The experimental parameters for maximum emulsified oil removal efficiency and effective regeneration of these adsorbents were determined. The optimum parameters in terms of adsorbent dosage, contact time, salinity, pH and temperature were 3.0 g/L, 20.0 min, 0 ppm, 7.0 and 25°C for both adsorbents. Due to their low density, multiwalledcarbon nanotubes could not be successfully employed in packed bed columns. The magnetite derivative has a larger density and hence, for the removal of emulsified oil from produced water packed bed column studies were performed utilizing multiwalled carbon magnetite nanotubes. The packed bed column efficiency and behaviour were evaluated using Thomas, Clark, Yan et al. and Bohart and Adams models. The Yan model was found to best describe the column experimental data. The adsorbents were regenerated using n-hexane and reused several times for oil removal from produced water without any significant decrease in their initial adsorption capacities. [ABSTRACT FROM AUTHOR]

In this study, the application of four synthetic resins for the removal of emulsified oil from produced water was investigated. Key experimental parameters such as adsorbent dosage, contact time, initial oil concentration and pH were evaluated for Optipore L493, Amberlite IRA 958, Amberlite XAD 7 and Lewatit AF 5. Oil removal rates upwards of 98% were achieved using AF 5, XAD 7 and L493. IRA 958 recorded very modest removal rates of less than 25%. Isotherm data were further investigated and fitted using Langmuir, Freundlich, Toth, Flory Huggins and Dubinin-Radushkevich models. The results show that the adsorption onto XAD 7 and L 493 is a multilayer adsorption process over a heterogeneous surface that is best illustrated by the Freundlich and Toth models respectively. The Dubinin-Radushkevich best described the removal using AF 5 resin that assumes that the adsorption process occurs on a heterogenous surface with a gaussian energy distribution. Kinetic studies assessing the rate of removal for each resin were conducted. Experimental results were best fitted using pseudo second order kinetics. It is concluded that XAD 7 had the highest kinetics among all tested resins. Also, AF 5 exhibited the highest adsorption capacity. Overall, the study confirmed the applicability of the resins for the removal of oil from produced water. • Polymeric adsorbents (Optipore L493, Amberlite XAD 7 and Lewatit AF 5) achieved oil removal rates of more than 98%. • Kinetic studies assessing the rate of removal for each resin were best fitted using pseudo second order. • Langmuir model fitted best adsorption isotherms obtained using resins XAD 7 and L 493 while D-R best described AF 5 resin. • No change in oil removal efficiency while varying pH. [ABSTRACT FROM AUTHOR]

Wastewater in petrochemical processes and produced water from oil and gas production remain a challenge for the industry to minimize their impact on the environment. Recent research and development of treatment technologies for petrochemical wastewater and produced water from oil and gas industries published in 2018 were summarized in this annual review. Great efforts and progresses were made in various treatment options, including membrane processes, advanced oxidation, biological systems, adsorption, coagulation, and combined processes. Practitioner points: Treatment technologies for petrochemical wastewater are reviewed.Research development in produced water from oil and gas industries is summarized.Reviewed technologies include traditional, advanced, and innovative processes. [ABSTRACT FROM AUTHOR]

The remaining challenging issue during oil production from reservoir is reduction of water production using a conformance control technique. As a new method, the feasibility of an electrorheological (ER) suspension for forming a solid-like structure to obstruct the pore throat in porous media was investigated. Suitable conducting nanoparticles for injection into an oil reservoir with regard to size, morphological shape, and field scale capability were synthesized and characterized, then dispersed in two types of oil: heavy and light crude oil. A series of ER experiments, including steady shear and dynamic tests were performed to determine the ability of the proposed conformance control fluid to produce a solid-like form with the electric field. The fluid was then modeled using both the Bingham and Herschel-Bulkley equations. The large ER behaviors proved feasibility of the proposed conformance controlling fluid for reducing water production, which can make the oil production operation more economical and environmentally friendly. [ABSTRACT FROM AUTHOR]

One way to conserve fresh water resources is by reusing water from wastewater. For instance, water can be removed from wastewater through formation of ice crystal layers by progressive freeze concentration (PFC). The application of PFC to remove water from produced water and biodiesel wastewater was assessed through the final concentration of concentrated wastewater and purity of melted ice crystals. No PFC study has been done on these applications. In order to evaluate the efficiency of PFC, the effective partition constant (K) and separation efficiency (SE) were calculated for the effect of stirring rate and coolant temperature. The results demonstrate that PFC is a more practical method for produced water, as compared to biodiesel wastewater which is based on the value of low K and high SE. [ABSTRACT FROM AUTHOR]

• PEC precipitates were formed between PAA and scale—forming divalent cations (Ba, Sr, Ca, and Mg). • PSS precipitated Ba and small amounts of Sr from mixed solutions, but not Ca or Mg. • Regeneration of PAA was achieved by adding HCl to release complexed cations. • 73% of scale-forming cations were removed from oil produced water by repeated addition of PAA. Divalent cations such as Ba2+, Sr2+, Ca2+, and Mg2+, commonly found in oil/gas produced water at high concentrations, adversely affect oil and gas production by forming scales in pipes, tanks, process equipment such as oil-water separators, and treatment equipment such as filters and reverse osmosis membranes. If the water is reinjected, e.g., for water flooding, scales may also form on the well screens and in the producing formation. Water soluble polyelectrolytes have been used to inhibit scale formation in oil and gas production and to eliminate cationic metals from water via membrane separation. However, the underlying interactions between scale-forming cations and various polyelectrolytes are not well understood. To this end, two commercially available anionic polyelectrolytes with different repeating functional groups, poly(acrylic acid) (PAA) and poly(sodium 4-styrenesulfonate) (PSS), were used to evaluate complexation and precipitation of Ba2+, Sr2+, Ca2+, and Mg2+ in binary systems, multi-ion mixtures, and produced water. The apparent dissociation constant (pKa) of PAA was determined by titration to be 6.7, indicating a high affinity of PAA for H+. The strength of the complexes formed between PAA and scale-forming cations (binding strength) decreased in the order Ba2+ > Ca2+ > Sr2+ > Mg2+ at pH 5. Higher pH values led to a higher affinity of PAA for divalent cations, which is attributable to the increase in binding sites for cations as the PAA more completely ionizes. By contrast, the affinity of PSS decreases in the order Ba2+ > Sr2+ > Ca2+ > Mg2+, with no significant pH effect. The formation and precipitation behavior of polyelectrolyte complexes (PECs) was investigated by reacting cations with the sodium salt of PAA (sodium polyacrylate) or with PSS. Only Ba2+ formed precipitates with PSS in single-cation solutions, although small amounts of Sr2+ were also removed by PSS from a mixed cation solution. However, all of the scale-forming cations formed PEC precipitates with PAA in both binary and mixed-ion solutions, depending on the cation concentration and molar ratio of PAA to divalent cations. The maximum amount of precipitation occurred at a molar ratio of PAA to M2+ of 1.5–1.7, while overdosing of PAA caused dispersion of the precipitates. High concentrations of monovalent cations inhibited precipitation of divalent cations with PAA. Up to 73% of scale-forming cations were removed from field-collected produced water samples through repeated (4 times) addition of PAA at a molar concentration ratio of 1. The release of scale-forming cations from PAA-M2+ precipitates, thereby regenerating PAA, was achieved by adding HCl. [ABSTRACT FROM AUTHOR]

In this article, one of Iran's southwest oil fields that produces 3200 barrels per day (bbl/d) of wastewater from oil and gas processing was investigated. Experimental analysis of oil reservoir water and desalting wastewater disposal of crude oil desalting unit was performed. First, water was treated with a reverse osmosis membrane. As a result, the purified water, with lower total dissolved solids (TDS) and pH, was a suitable candidate for injection into the adjacent wells of the crude oil desalting unit. The effectiveness and compatibility of this wastewater to the formation water of the oil field wells were simulated. Finally, we studied and identified the formation, the amount, and the type of mineral scale deposits. These are the most important problems during water injection into the wells. The analysis shows that the refined water from the reverse osmosis (RO) process was a suitable and low-cost economical option for injection in onshore and offshore fields, due to the low amount of salts, the concentration of susceptible ions in scaling formation, and the appropriate pH. This oil field, which is in the second half of life, requires enhanced oil recovery methods (EOR) for the maintenance of pressure and an increase in oil recovery. [ABSTRACT FROM AUTHOR]

Produced water is the largest waste stream associated with oil and gas exploration and production operations. Most produced water generated onshore is managed by permitted injection in deep underground wells, but alternative disposal options including reuse are increasingly being considered. However, insufficient understanding of the composition and toxicity of produced water imposes significant constraints on effective management of potential short‐term and long‐term risks associated with such alternative uses. As interest builds for management options, such as surface discharge, livestock watering, irrigation, and other industrial uses, research is needed to assess produced‐water hazards and exposures to both humans and the environment. This challenge affords an opportunity to capitalize on emerging risk assessment tools. Innovative and comprehensive approaches to filling data gaps and assessing produced water risks will be imperative. A group of experts from industry, academia, and government were assembled to define research needs to support objective decision making on the acceptability, or lack thereof, of produced water disposal alternatives. Presented here are key outcomes from that workshop and recommendations for a research framework to assess toxicity of produced water and associated risks from above ground discharge and reuse options. Integr Environ Assess Manag 2019;15:677–682. © 2019 SETAC. Key Points: In parts of the United States, permitted release of oil and gas wastewater (called produced water), either to surface waters or to land to supplement water requirements for livestock, agriculture, municipalities, or other industries is being actively implemented or investigated.Critical information gaps regarding the chemical characteristics and toxicity of produced water constituents limit efforts to comprehensively identify or mitigate potential hazards, leaving decision‐makers ill‐equipped to make informed choices with respect to produced water management.Monitoring strategies such as those for chemicals of emerging concern (CECs) for municipal wastewater recycling, and predictive chemical testing approaches (e.g., high‐throughput screening) often used to evaluate data‐poor chemicals can inform, and be integrated into, a produced water research strategy.The need to understand hazards and risks of produced water, provides a real‐world opportunity to explore how predictive chemical testing approaches may be integrated with other types of information for use by policy makers, regulators, operators, and end‐users. [ABSTRACT FROM AUTHOR]

Produced water (PW) from oil and gas operations is considered a potential resource for food crop irrigation because of increasing water scarcity in dryland agriculture. However, efforts to employ PW for agriculture have been met with limited success. A greenhouse study was performed to evaluate the effects of PW on physiological and morphological traits of spring wheat (Triticum aestivum). Plants were irrigated with water treatments containing 10 and 50% PW (PW10 and PW50, respectively) and compared to a matching 50% salinity (NaCl50) and 100% tap water controls. Compared to controls, plants watered with PW10 and PW50 exhibited developmental arrest and reductions in aboveground and belowground biomass, photosynthetic efficiency, and reproductive growth. Decreases in grain yield ranged from 70 to 100% in plants irrigated with PW compared to the tap water control. Importantly, the PW10 and NaCl50 treatments were comparable for morphophysiological effects, even though NaCl50 contained 5 times the total dissolved solids, suggesting that constituents other than NaCl in PW contributed to plant stress. These findings indicate that despite discharge and reuse requirements focused on total dissolved solids, salinity stress may not be the primary factor affecting crop health. The results of the present study are informative for developing guidelines for the use of PW in agriculture to ensure minimal effects on crop morphology and physiology. Environ Toxicol Chem 2019;38:1756–1769. © 2019 SETAC [ABSTRACT FROM AUTHOR]

The significant development of oil and gas from the Marcellus Shale and other geological formations in Pennsylvania over the last decade has generated large volumes of liquid and solid waste. In this paper we use data reported to the Pennsylvania Department of Environmental Protection (PADEP) to examine temporal and spatial trends in generation and management of liquid and solid waste from both conventional and unconventional oil and gas activities in Pennsylvania between 1991 and 2017. While previous assessments have examined this waste inventory in part, no complete assessment of waste quantity, waste types, waste handling practices, and spatial waste tracking has been undertaken using all currently available years of Pennsylvania oil and gas waste data. In 2017 more than half of oil and gas wastewater by volume was reused at well pads to facilitate more hydrocarbon production while the majority of solid waste by volume was disposed of at in-state landfills. The spatial resolution of wastewater generation and handling from unconventional operations has improved substantially with recent regulations and reporting requirements; however, conventional oil and gas development was not held to more stringent reporting requirements and thus spatially-explicit data on wastewater generation and handling from conventional oil and gas development is still lacking. In addition, a third of the liquid waste across all years in the inventory lack a reported final destination. Spatially explicit cradle-to-grave reporting of waste generation and waste handling from both conventional and unconventional oil and gas development is critical to assess potential environmental and human health hazards and risks associated with oil and gas development. Unlabelled Image • Majority of Pennsylvania oil & gas (O&G) wastewater is disposed of in-state. • Final disposal endpoints are often not reported in the PADEP waste inventory. • 30% of O&G wastewater generated since 1991 is from conventional development. • The majority of wastewater is currently handled by in-field reuse (52% in 2017). • Spatial data available for 99% of UOG and 45% of COG wastewater in 2017. [ABSTRACT FROM AUTHOR]

Management of coalbed methane (CBM)-produced water is a crucial part of the water–energy nexus, especially as CBM is projected to play a key role as a bridge fuel in major economies. In this paper, we consider one management technique, i.e., desalination of CBM-produced water to generate potable water. We discuss a confluence of geographic, sociotechnical, regulatory, and other circumstances that could make this concept viable for select coal-bearing regions. Having said that, for maximizing benefits, it is prudent to take a synergistic view targeting multiple objectives (water access, health, environmental impacts, and ease of waste management). Thus, we make design recommendations and suggest a system-evaluation framework for making sustainable decisions related to produced-to-potable water systems. For instance, a key question is whether such systems should be centralized or decentralized—and this paper highlights crucial tradeoffs that are present in both the cases. [ABSTRACT FROM AUTHOR]

• Consortia enriched from evaporation pond soil (EVPS) showed higher growth. • Supplementing produced water with yeast extract yielded 62% COD removal with EVPS. • Microbial analysis of EVPS showed bacterial genera have more richness and diversity. • Identification of EVPS genera indicated it is potentially suitable for PW treatment. The idea at the core of the research reported in the present paper is the use of indigenous halophilic consortia of an oilfield for treatment of the produced water (PW) generated in the same oilfield. To test this idea water and soil-based microbial sources obtained from desalination units of two oilfields were enriched in PW obtained from the same oilfield and supplemented with either yeast extract (YE) or Mueller-Hinton medium containing crude oil. Enriched soil-based microbial consortia (termed EVPS) gave a meaningfully higher maximum achievable biomass concentration, and amount of COD removed when grown on PW supplemented with YE compared to enriched water based ones. The supplementation of PW with inorganic nitrogen and phosphorous sources resulted in around 35% COD removal whereas supplementation with YE increased the PW COD removal to 62%. Microbial analysis of EVPS with Illumina HiSeq/MiSeq showed that bacteria had higher richness and diversity than archaea. The dominant bacteria genera were Chromohalobacter , Idiomarina, and Marinobacter , whereas Haloterrigena , Haloferax , and Methanohalophilus were the dominant genera amongst the archaea. Based on previous reports, the identified genera in EVPS have a wide salt tolerance range and are collectively capable of biodegrading most of the organic compounds prevalent in PW. [ABSTRACT FROM AUTHOR]

Induced air flotation (IAF) was used to recover the total polycyclic aromatic hydrocarbons (PAHtot) from produced water (PW), a real oilfield effluent sampled from the hydrocarbon storage tanks at SONATRACH of Bejaia. Tween 80 was used as a collector at a test concentration of 0.5% (V/V%) and ethanol was used as a frother at a test dosage of 0.5 mL/1000 mL of PW. The natural presence of NaCl at greater concentrations may improve the removal efficiency of PAHtot from PW by IAF. We found that the conditioning step before initiating the flotation process is important for PAHtot recovery. A PAHtot recovery of 93.67% was achieved at 30 min of conditioning and 20 min of flotation. We also found that in the presence of Tween 80 during the conditioning step, PAHtot have a tendency to reach the water-air surface. It was disclosed that the addition of ethanol in PW during the conditioning has reduced both the conditioning time from 30 min to 10 min and the flotation time from 20 min to 12 min, which is beneficial from an economic standpoint. The effect of ethanol on the flotation kinetics of PAHtot was explained well by the Higuchi model. [ABSTRACT FROM AUTHOR]

Oil exploration waste, also called produced water, contains hazardous pollutants, such as benzene; benzene, toluene, and xylene (BTX); naphthalene, phenanthrene, and dibenzothiophene (NDP); polyaromatic hydrocarbons (PAHs); and phenol. Produced water is characterized by high chemical oxygen demand (COD) and oil content, which exceed the standard limits of regulation. In this study, the combination of ultrafiltration (UF) and ozone pre-treatment and post-treatment were applied for treatment of produced water to minimize its environmental impact. Produced water and membrane were characterized, and their ultrafiltration performance for removal of oil content, benzene, toluene, xylene, and COD. Two commercial Polyethersulfone membranes, with molecular-weight cutoff values of 10 and 20 kDa, were used. The membrane flux profile illustrated that ozone pre-treatment had higher normalized flux than UF only. Separation performance was evaluated based on flux profile and removal of COD, oil and grease content, toluene, and xylene. Significant finding was found where the combination of UF with ozone pre-treatment and post-treatment could significantly eliminate COD, oil content, toluene, and xylene. The rejection of these components was found higher than conventional process, which was in the range of 80% to 99%. In addition, almost oil and grease can be removed by using this combined system. Permeate quality of this system confirmed the acceptable level as water discharge. [ABSTRACT FROM AUTHOR]

The petroleum industry has an increasing interest in understanding the microbial communities driving biofouling and biocorrosion in reservoirs, wells, and infrastructure. However, sampling of the relevant produced fluids from subsurface environments for microbiological analyses is often challenged by high liquid pressures, workplace regulations, operator liability concerns, and remote sampling locations. These challenges result in infrequent sampling opportunities and the need to store and preserve the collected samples for several days or weeks. Maintaining a representative microbial community structure from produced fluid samples throughout storage and handling is essential for accurate results of downstream microbial analyses. Currently, no sample handling or storage recommendations exist for microbiological analyses of produced fluid samples. We used 16S rRNA gene sequencing to monitor the changes in microbial communities in hypersaline produced water stored at room temperature or at 4 °C for up to 7 days. We also analyzed storage at −80 °C across a 3-week period. The results suggest ideal handling methods would include placing the collected sample on ice as soon as possible, but at least within 24 h, followed by shipping the samples on ice over 2–3 days, and finally, long-term storage in the −20 °C or −80 °C freezer. [ABSTRACT FROM AUTHOR]

In 2012, the Oslo–Paris (OSPAR) Commission adopted Recommendation 2012/5 for a risk‐based approach (RBA) to the management of produced water discharges from offshore installations. As part of this recommendation, OSPAR requires that the environmental risk of the discharge of produced water is characterized based on whole effluent toxicity (WET) studies and/or on a substance‐based assessment. In this paper we describe an assessment of the likelihood that the environmental risk of produced water discharges is adequately controlled based on WET data for 19 oil‐ and gas‐producing platforms and their discharge volumes. Our analysis shows that, with the selected risk criterion of predicted exposure concentration (PEC)/predicted no‐effect concentration (PNEC) should not exceed 1 at 500 m, there is a mean likelihood of 99.5% (or more) that the environmental risk from the produced water discharges is adequately controlled for installations that discharge 30 × 103 m3/y (or less). The method presented in this paper can be used for screening purposes to ensure that efforts are directed toward installations with a high likelihood that risk is not adequately controlled. Integr Environ Assess Manag 2019;15:584–595. © 2019 SETAC Key Points: Whole effluent toxicity (WET) studies on produced water discharges from offshore installations can be used to assess the likelihood of produced water to be adequately controlled.Our analysis shows that, with the selected risk criterion PEC/PNEC should not exceed 1 at 500 m, installations that discharge 30 000 m3/y (or less) have a likelihood of 99.5% (or more) that the environmental risk from the produced water discharge is adequately controlled.The analysis presented in this paper can be used for screening purposes to ensure that efforts are focused on the installations with a high likelihood of having a risk that is not adequately controlled. [ABSTRACT FROM AUTHOR]

Nowadays, petroleum is the most used energy source in the world, however it also produces a great volume of a residue denominated produced water (PW). This water has no commercial value and requires treatment, due to potential contaminants in its composition, in order to be destined for disposal or reinjection during recovery methods. In this way, the produced water management needs specific process support it, becoming costly. Therefore, the present work proposes a continuous monitoring methodology of the water-oil ratio, aiming to subsidize the field viability analyses. Once that the wateroil ratio data are auto-correlated, some adjustments are needed before the application of the control charts. Therefore, ARIMA models were adjusted to the data, evaluating the accuracy of the models, then, the control charts were built based on the residues. In this paper, the type of control charts considered was a Shewhart for the averages. The performance of the chart was evaluated through simulations and it was determined that it is efficient to detect big deviations, but slow to small deviations. [ABSTRACT FROM AUTHOR]

Goal: Industry 4.0 enables the design of new models for process monitoring in which sensors, analyzers, and controls are positioned at different points in the process. The goal of this work is to present the modeling and control of a three-phase production separator with hydrocyclones to treat produced water on an oil platform of mature fields. Design / Methodology / Approach: The Methodology or approach used was to develop a model for the primary separator that allows its operation by means of a controller (fuzzy and PI) to manipulate the flow of discarded water, acting indirectly in the oil-in-water measure. Results: The results showed the consistency of the model for open loop simulations and the effectiveness of the controllers to comply with the discarding requirements for the closed-loop simulations. Limitations of the investigation: The limitation of the model and developed controllers is that they are only applied to platforms where water production exceeds the separators discharge capacity and the exceeding water can be offloaded to another equipment or to another platform. Practical implications: The main practical implications of this study are to maximize the flow of discarded water on mature field platforms, which produces elevated amounts of water, to conform the total oil and grease to the local law regulations. Additionally, it also increases oil production, with a higher limit of water production. Originality / Value: Compared to the previous authors, where the models of discarded flow is a function of the water-oil interface, this work developed a model that allowed the flow of the discarded water to be a function of its quality. [ABSTRACT FROM AUTHOR]

Co-treatment of hydraulic fracturing produced water (PW) with municipal wastewater is a cost-effective shale gas PW management option. However, little attention has been paid to the impact of PW on the reliability of bioprocess in municipal wastewater treatment plants, in this study, a mature chemical pretreatment method was used to remove a large proportion of organic matters in real PW. Then a laboratory-scale moving bed biofilm reactor (MBBR) was established for the co-treatment of pretreated PW and synthetic domestic wastewater. Results showed that CODcr removal rate reached above 90% and acute toxicity was lowered by 20% in the pretreatment of PW using consecutive Fenton-NaCIO oxidation. After 68 days of slowly increasing the mixing ratio, complete nitrification-denitrification was established with a maximum mixing ratio of 50%. The mean total nitrogen (TN) removal rate reached above 60% when the MBBR operated under maximum mixing ratio for the following 38 days. Shotgun metagenomic analysis revealed high taxonomic structure similarity between suspended and attached growth biomass in the MBBR when the mixing ratio was maintained at 50%. The functional diversity of nitrite-oxidizing bacteria may be present in the saline biological nitrogen removal system and may strengthen nitrogen and other typical element cycles. [ABSTRACT FROM AUTHOR]

• Demonstrated transport and biodegradation of hydraulic fracturing wastewater components. • Characterized a microbial consortium capable of degrading all target compounds. • Extractive membrane bioreactor achieved successful remediation of organic contaminants. • Performance comparison revealed advantages of Hytrel™ over PDMS membranes. The biodegradation of selected organic constituents present in hydraulic fracturing wastewater were examined in an extractive membrane bioreactor (EMB) operating with Hytrel™ 3548 tubing. Synthetic hydraulic fracturing wastewater was generated via an extensive literature review and contained high concentrations (1000 mg L−1) of contaminant compounds of varied hydrophobicity, viz. methyl ethyl ketone, benzene, phenol and acetic acid, as well as 30–120 g L−1 of Cl− at low pH. This hostile wastewater was circulated through the polymeric tubing, selectively transporting the organic compounds through the membrane for biological degradation by an enriched bacterial consortium. 16S rDNA analysis revealed the presence of five dominant microbial strains within the consortium, including: Pseudomonas sp., Comamonas sp., Achromobacter sp., Lysinibacillus sp., and Oxalobacter sp. EMBs in batch operation achieved 99% removal of methyl ethyl ketone, benzene, and phenol after 72 h and effectively removed acetic acid up to its ionization point. Continuous EMB operation provided 99% removal of benzene and phenol, 96% removal of methyl ethyl ketone, and 53% of acetic acid. The treatment of synthetic hydraulic fracturing fluid demonstrated the effectiveness of carefully selected amphiphilic polymers in EMBs for treating the hydrophilic and hydrophobic organic profile found in hydraulic fracturing wastewaters. [ABSTRACT FROM AUTHOR]

Regular discharges of produced water from the oil and gas industry represents the largest direct discharge of effluent into the marine environment worldwide. Organic compound classes typically reported in produced water include saturated hydrocarbons, monoaromatic and polyaromatic hydrocarbons (MAHs, PAHs) as well as oxygenated compounds, such as phenols, acids and ketones. This forms a cocktail of known and suspect toxicants, but limited knowledge is yet available on the sub-lethal toxicity of produced water to cold-water marine fish species. In the present work, we conducted a 4-day exposure of embryos of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to produced water extracts equivalent to 1:50, 1:500 and 1:5000 times dilutions of raw effluent. No significant reduction in survival or hatching success was observed, however, for cod, hatching was initiated earlier for exposed embryos in a concentration-dependent manner. During recovery, significantly reduced embryonic heart rate was observed for both species. After hatch, larvae subjected to embryonic exposure to produced water extracts were smaller, and displayed signs of cardiotoxicity, jaw and craniofacial deformations. In order to improve risk assessment and regulation of produced water discharges, it is important to identify which produced water components contribute to these effects. • Atlantic cod and haddock embryos were exposed to produced water extracts mimicking 50–5000 times dilution of produced water. • Exposure to produced water caused no significant effects on acute mortality and hatching success. • Delayed effects were observed in larvae displaying symptoms of cardiotoxicity and developmental deformations. [ABSTRACT FROM AUTHOR]

• Co-treatment of hydraulic fracturing produced water with sewage at a mixing ratio of 50%. • Fenton–NaClO pretreatment of produced water could substantially reduce COD Cr and acute toxicity. • EEM–PARAFAC identified the degradation situation of the produced water in pretreatment process. • 60% total nitrogen was removed in the biological co-treatment reactor under a mixing ratio of 50%. • Metagenomic analysis revealed the potential functional diversity of nitrite–oxidizing bacteria. Co-treatment of hydraulic fracturing produced water (PW) with municipal wastewater is a cost-effective shale gas PW management option. However, little attention has been paid to the impact of PW on the reliability of bioprocess in municipal wastewater treatment plants. In this study, a mature chemical pretreatment method was used to remove a large proportion of organic matters in real PW. Then a laboratory-scale moving bed biofilm reactor (MBBR) was established for the co-treatment of pretreated PW and synthetic domestic wastewater. Results showed that COD Cr removal rate reached above 90% and acute toxicity was lowered by 20% in the pretreatment of PW using consecutive Fenton–NaClO oxidation. After 68 days of slowly increasing the mixing ratio, complete nitrification–denitrification was established with a maximum mixing ratio of 50%. The mean total nitrogen (TN) removal rate reached above 60% when the MBBR operated under maximum mixing ratio for the following 38 days. Shotgun metagenomic analysis revealed high taxonomic structure similarity between suspended and attached growth biomass in the MBBR when the mixing ratio was maintained at 50%. The functional diversity of nitrite-oxidizing bacteria may be present in the saline biological nitrogen removal system and may strengthen nitrogen and other typical element cycles. [ABSTRACT FROM AUTHOR]

Abstract Massive volume of produced water laden with surfactants is generated from enhanced oil recovery (EOR) platform. Besides surfactants, this produced water also holds various organic and inorganic pollutants which requires intensive treatment before being discharged offshore. Current research focused on a radical solution for actual application in which the PVDF-TiO 2 hollow fiber photocatalytic membranes were fabricated to simultaneously separate and degrade the surfactants laden in produced water. The characterization study portrayed the membranes with increasing TiO 2 nanoparticles exhibited an improvement in surface hydrophilicity, porosity and tensile strength; besides, having an appropriate surface morphology and topology to remove the surfactants from produced water. Nevertheless, an excessive loading of TiO 2 nanoparticles beyond 2 wt% had deteriorated the membrane performances in terms of flux and surfactant rejection measured as COD removal. These deteriorations were justified by the agglomeration of excessive TiO 2 nanoparticles as observed occluding the pores on membrane surface. In predicting the membrane flux and rejection amidst the simultaneous separation and degradation of surfactants from produced water, two statistical models were subsequently derived by manipulating the produced water pH and air bubble flow rate (ABFR) of reactor operating conditions. The models permitted the fundamental comprehension of the correlations between the membrane flux and rejection parameters against the reactor operating conditions. Considering these correlations, the optimization of reactor operating conditions was finally evaluated and determined to achieve at the pH of 6.00 and ABFR of 0.41 L/min, giving rise to the membrane flux and rejection of 47.95 ± 1.34 L/m2h and 66.73 ± 0.76%, respectively. Graphical abstract Image 1 Highlights • Characterization of various titanium dioxide hollow fiber photocatalytic membranes. • Simultaneous separation and degradation of surfactants laden in produced water. • Modeling of membrane performances described by reactor operating conditions. • Optimization of operating conditions using response surface methodology software. [ABSTRACT FROM AUTHOR]

Abstract Water generated by hydraulic fracturing for the production of oil and gas, commonly termed 'produced water', may contain residual organic compounds from the fracturing process or the subsurface formation. Biological treatment is a potential technology to remove residual organic compounds in produced water. Biocides are often added to both fracturing fluids and produced water to limit undesirable microbiological activity, and glutaraldehyde is the most commonly used biocide in hydraulic fracturing. Residual biocides in produced water can limit biological treatment efficiency. We evaluated the effect of glutaraldehyde on the biodegradation of five of the most commonly reported organic compounds in hydraulic fracturing fluids in an engineered biofilm treatment. Our results demonstrated that glutaraldehyde delays biological organic compound removal by introducing a biodegradation lag phase. In addition, the effects of glutaraldehyde were more pronounced for more rapidly degraded compounds. Finally, the presence of glutaraldehyde did not decrease microbial abundance nor drive microbial community structure, suggesting that observed effects were due to altered microbial activity. These results highlight the necessity to consider co-contaminant interactions during treatment of complex waste streams where residual biocide may be present. Graphical abstract Unlabelled Image Highlights • Evaluated the effect of glutaraldehyde on hydraulic fracturing compound biodegradation • Glutaraldehyde delays biological organic compound removal. • Glutaraldehyde effects were more pronounced for more rapidly degraded compounds. • Glutaraldehyde did not decrease microbial abundance or alter community structure. [ABSTRACT FROM AUTHOR]

Abstract Produced water (PW) is a wastewater generated in large quantities from the extraction of oil and gas. PW found to have high amounts of dissolved solids (TDS) and residual petroleum hydrocarbons causing considerable damage to the environment. PW also contains sulfates in significant amounts, due to which treating this wastewater is essential prior to discharge. The present study was aimed for bioelectrochemical treatment of PW and simultaneous bioelectrogenesis in the two most studied configurations viz., single and dual chamber microbial fuel cells (MFCs). The study evidenced treatment of recalcitrant pollutants of PW. Both MFCs were operated by keeping similar operating conditions such as anode chamber volume, hydraulic retention time (HRT) for batch mode of operation, electrode materials, inlet characteristics of PW and ambient temperature. Among both configurations, dual chamber MFC showed higher efficiency with respect to bioelectrogenesis (single chamber - 789 mW/m2; dual chamber – 1089 mW/m2), sulfates removal (single chamber – 79.6%; dual chamber – 93.9%), total petroleum hydrocarbons removal (TPH, single chamber – 47.6%; dual chamber – 53.1%) and chemical oxygen demand degradation (COD, single chamber – 0.30 kg COD/m3-day (COD removal efficiency, 54.7%); dual chamber – 0.33 kg COD/m3-day (COD removal efficiency, 60.2%)). Evaluated polarization behavior of both MFCs were also evidenced the effective response of the electroactive anodic biofilm. Graphical abstract Unlabelled Image Highlights • Produced water (PW) evaluated for bioelectrogenesis in two configurations of MFCs • Dual chamber MFC showed better performance for produced water treatment and electrogenesis than single chamber. • Petroleum hydrocarbons degradation present in PW resulted in efficient power generation • Sulfates and chemical oxygen demand removal were evidenced from both MFCs. [ABSTRACT FROM AUTHOR]