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Oil and gas production wells generate large volumes of water mixed with hydrocarbons (dispersed and dissolved), salts (ions), and solids. This 'produced water' (PW) is a waste stream that must be disposed of appropriately. The presence of toxic hydrocarbons and ions in PW makes it unsuitable for surface discharge or disposal in groundwater resources. Thus, PW is often injected into deep geological formations as a disposal method. However, the supply of global water sources is diminishing, and the demand for water in industrial, domestic, and agricultural use in water-stressed regions makes PW a potentially attractive resource. PW also contains valuable elements like lithium and rare earth elements, which are increasing in global demand. This review article provides an overview of constituents present in PW, current technologies available to remove and recover valuable elements, and a case study highlighting the costs and economic benefits of recovering these valuable elements. PW contains a promising source of valuable elements. Developing technologies, such as ceramic membranes with selective sorption chemistry could make elemental recovery economically feasible and turn PW from a waste stream into a multi-faceted resource. [ABSTRACT FROM AUTHOR]

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

The demand for freshwater continuously increases with hydraulic fracturing operations, mainly due to unconventional reservoirs. For instance, approximately 7000–18,000m3 of water is required per well for hydraulic fracturing. Meanwhile, almost 100bbl of produced water is produced annually worldwide in oil and gas. This study aims to develop a robust hydraulic fracturing fluid with untreated produced water and to study the feasibility of the produced water as a freshwater substitute for fracking fluid. Produced water from the Angsi field was used as the main produced water with high Total Dissolved Solids. The water was then mixed with guar gum, and crosslinker and polymer degradation after mixing was examined accordingly. The new fracturing fluid has a viscosity of 520cP and 1.015 g/cm3 density. A static adsorption test was carried out, and the fluid-rock interaction was checked. The changes of rock were also investigated using Scanning Electron Microscopy, X-Ray Fluorescence, and Energy-Dispersive X-ray. Apart from that, the rock-fluid interaction was examined through a wettability test, and the properties of fracturing fluid were investigated through interfacial tension and rheometer. The SEM and Poroperm tests revealed that there was no significant physical damage to the sandstone surface. According to the wettability analysis, the contact angles for sandstone surface-produced water–gas and sandstone surface-hydraulic fracturing-gas were 56.2° and 62.8°, respectively. The static adsorption was discovered to be 5.529 g/g. Hence, it is recommended to use the produced water for fracking fluid synthesis, reducing freshwater usage. [ABSTRACT FROM AUTHOR]

This paper studied the adsorption of chemical oxygen demand (COD), oil and turbidity of the produced water (PW) which accompanies the production and reconnaissance of oil after treating utilizing powdered activated carbon (PAC), clinoptilolite natural zeolite (CNZ) and synthetic zeolite type X (XSZ). Moreover, the paper deals with the comparison of pollutant removal over different adsorbents. Adsorption was executed in a batch adsorption system. The effects of adsorbent dosage, time, pH, oil concentration and temperature were studied in order to find the best operating conditions. The adsorption isotherm models of Langmuir, Freundlich and Temkin were investigated. Using pseudo-first-order and pseudo-second-order kinetic models, the kinetics of oil sorption and the shift in COD content on PAC and CNZ were investigated. At a PAC adsorbent dose of 0.25 g/100 mL, maximum oil removal efficiencies (99.57, 95.87 and 99.84 percent), COD and total petroleum hydrocarbon (TPH) were identified. Moreover, when zeolite X was used at a concentration of 0.25 g/100 mL, the highest turbidity removal efficiency (99.97%) was achieved. It is not dissimilar to what you would get with PAC (99.65 percent). In comparison with zeolites, the findings showed that adsorption over PAC is the most powerful method for removing organic contaminants from PW. In addition, recycling of the consumed adsorbents was carried out in this study to see whether the adsorbents could be reused. Chemical and thermal treatment will effectively regenerate and reuse powdered activated carbon and zeolites that have been eaten. [ABSTRACT FROM AUTHOR]

In addition to being used as an energy source, coal also has significant potential for other, more sustainable uses including water treatment. In this study, we present a simple approach to treat water that was produced during oil production and contained a total dissolved solids (TDS) content of over 150 g/L using Powder River Basin (PRB) coal. PRB coal used as packing material in a flow-through column effectively removed 60%–80% of the cations and anions simultaneously. Additionally, 71%–92% of the total organic carbon in the produced water was removed as was all of the total suspended solids. The removal mechanisms of both cations and anions were investigated. Cations were removed by ion exchange with protons from oxygen-containing functional groups such as carboxylic and phenolic hydroxyl groups. Anions, mainly Cl−1, appeared to be removed through either the formation of resonance structures as a result of delocalization of electrons within coal molecules or through ion–π interactions. We propose that coal is a "pseudo-amphoteric" exchange material that can remove cations and anions simultaneously by exchanging ions with both ionized and non-ionized acids that are ubiquitous in coal structure or resonance effect. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) produced from waste coconut shells in Trinidad and Tobago was investigated as a sustainable method for adsorption of the pollutant phenol from produced water. Activation of produced char was optimized at 900°C for 10 min using a N2 flowrate of 96 ml/min and CO2 gas at a flowrate of 96 ml/min, and the associated kinetic and thermodynamic parameters of the phenol‐AC interaction was experimentally obtained. The maximum adsorption capacity was 0.027 mg phenol/g adsorbent (equilibration time of 2 h and initial phenol concentration of 2 mg/L) and the data satisfied a pseudo‐second order kinetic model fitted indicating the chemically rate controlled mechanism. The Freundlich isotherm modeled the adsorption data best with a maximum equilibrium constant, KF of 0.138 occurring at 85°C. The standard enthalpy change and standard entropy change were 155.48 kJ/mol and 0.44 kJ/mol K respectively and the Gibbs free energy change ranged from 5.89–46.3 kJ/mol for the temperature range studied. The results obtained provide key parameters for the design of an adsorption column containing the locally produced AC adsorbent for the sustainable treatment of produced water. [ABSTRACT FROM AUTHOR]

Produced water is a complex mixture of organic and inorganic compounds and it is mainly salty water. It represents the largest volume of by-products generated during oil and gas recovery operations. As a result, water to oil ratio is around 3:1 that is water cut is 70%. Increasing volume of wastewater over the world has become a big issue of concern, and treatment of this wastewater can generate additional sources of potable water. Therefore, research efforts are devoted to developing a cost-effective technique to reduce high salinity of produced water to a lower value. A new approach is investigated, to remove/reduce salts from moderate to high concentration brine. This method is based on liquid-liquid extraction, and uses an organic phase containing ethanol, cyclohexane and sunflower oil. Experiments were successful to reduce the salinity of brine to approximately 27%–64%, in a single stage, with different concentrations of brine from 40,000 ppm up to 140,000 ppm. This method, is considered to be simple, efficient, environmentally-friendly and uses a sustainable system. [ABSTRACT FROM AUTHOR]

The federal research project, PAkmem, deals with the recycling of industrial wastewater. The aim of the project is to develop and pilot an innovative integrative process for produced water treatment in the oil and gas industry utilizing flotation and ceramic micro-nano-membrane filtrations (MF-NF membranes) as well as the wastewater treatment of the ceramic industry with ceramic NF-membranes and electrodialysis (ED). The process utilized should remove fine particles, organic matter and divalent ions in order to make the water dischargeable or reusable (direct disposal or reuse as process water in the ceramic industry and the enhanced oil recovery reinjection in the oil and gas industry in which the water is conditioned in order to increase the oil production yield). Three pilot plants were designed and built according to strict safety standards and were operated on industrial manufacturing sites in Germany in 2019. Two innovative optical fine particle measuring techniques (inline and online) have been specially adapted for the project and integrated into the pilot plants. The results show promising technical potential for the use of ceramic membranes in the above-mentioned applications. HIGHLIGHTS Produced water treatment using ceramic membranes shows promising results in removing both oils and solids.; Economics of flotation in combination with ceramic membrane filtration prove more advantageous than external disposal.; MF, ED and RO remove COD, suspended solids and conductivity from industrial ceramic wastewaters.;

Abstract Crude oil and produced water samples obtained from ten wells in an offshore field, Niger Delta, were analyzed, in order to determine the occurrence of naphthenates deposition in the field. Total acid number (TAN) and °API of the crude oil samples, pH and metal ions concentrations of the produced water samples were determined. The results revealed that TAN values ranged from 0.47 to 1.01 mgKOH/g with pH of 6.9–8.9, which were above established threshold. The metal ions concentrations especially for Ca++ and Na+ were relatively high. These imply a high possibility of metal-naphthenate precipitation in the oil production facilities in this field.

The water produced from the coalbed methane (CBM) wells contains abundant geochemical information, which is of great significance in evaluating the productivity of these wells. Based on the data of water produced from five CBM wells, geochemical characteristics of the produced water and its influence on the productivity of the wells are analyzed in Laochang Block. The results show that with the increase in the produced water of the five wells, δD and δ18O show a downward trend in general, reflecting that the influence of coal seams and surrounding rock on the produced water is weak, while the water–rock interaction of the Y-3 and Y-5 wells is more stable than that of the Y-1, Y-2, and Y-4 wells. Combining the water production characteristics of the Y-3 and Y-5 wells with better drainage and recovery effects, it is proposed that 0 ≤ σM < 0.3 and 0 ≤ σY < 600 or 0.7 < σM < 0.8 and 1,200 < σY < 1,300, and the fluctuation ranges of Ca2+, Mg2+, HCO3− and SO42− can provide a basis for quantitative characterization and evaluation of CBM well production.

Abstract Produced water (PW) from petroleum reservoirs often contains heavy metals and other contaminants that are harmful to the environment. Most of the commonly used treatment techniques have been reported to be ineffective in reducing some of the contaminants’ concentrations to recommended disposal levels. This study evaluated the effectiveness of four selected bio-adsorbents combined for treating PW from Niger Delta oil fields. In this study, orange peels (I), banana peels (II), sponge gourd (Luffa cylindrica) (III) and palm kernel fibers (IV) were washed with distilled water, sun-dried (24 h) and dried in the oven at 105 ± 5 °C (3 h, I and II), 150 °C (30 min, III) and 80 °C (3 h, IV). They were ground into powder, sieved (150 μ, Group A) and (300 μ, Group B), washed with 0.4 mol/L HNO3, filtered and rinsed with distilled water. Samples of PW were obtained from fields R, X, and Y in the Niger Delta and analysed for heavy metals using an atomic absorption spectrophotometer (AAS). Samples were treated in adsorption column over 6 h using the adsorbents simultaneously. Treated samples were analysed with AAS and characterised. Adsorption of heavy metals were assessed using Langmuir and Freundlich models. Data were analysed using regression and other statistical methods. For the 150 μ size of sample R, the percentage reductions for the metal concentrations (Pb, Ni, Cd, Cu, Fe, Mg, Cr, Zn, Mn, Ca, Ar, B, Sn and Ba) were found to be 100%, 52.7%, 100%, 100%, 85.87%, 19.48%, 100%, 92.8%, 17.74%, 98.86%, 22.32%, 29.56%, 78.06% and 44.74%, respectively, while the reduction in 300 μ size were 1.52%, 97.2%, 71.4%, 17.1%, 43.8%, 45.6%, 7.04%, 89.6%, 35.4%, 99.6%, 0.0001%, 1.19%, 14.19% and 0.002%, respectively. The finer adsorbents were more effective. Similar results were obtained for PW samples from the other fields. Produced water from Niger Delta oil fields was effectively treated of contaminants using four selected bio-adsorbents mixed simultaneously.

The removal of Iron from produced water using adsorbent materials is taking a space of attention from the perspective of researchers. In this work, the characterization of chemically modified silica used as Iron ions adsorbent using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), laser granularity instrument was performed. The point of zero charge (PZC) of modified silica was determined using titration method. Different parameters were used to better approach Iron removal. These parameters are 0.2 and 0.4 mg/l modified silica adsorbent dose, 30-180 min adsorption time and pH values of 4-10. The results showed that modified silica exhibited higher removal efficiency of Iron due to its surface characteristics. The results also showed that at 60 min adsorption time and pH 7, the maximum Iron removal efficiency with 99.99% and 99.98% was obtained using modified silica dose of 0.4 mg/l and 0.2 mg/l, respectively.

This paper presents three variable step size P&O algorithms for optimizing the separation efficiency of a coalescing pump/deoiling hydrocyclone produced water treatment system. By continuously adjusting the pumping pressure, and subsequently the coalescing effect, the algorithms are used to minimize the oil concentration downstream the hydrocyclone. Due to the variable step size, the algorithms react rapidly to changes in the upstream produced water characteristics, at the same time as they reduce (or eliminate) steady-state oscillations. Based on both simulation and experimental testing, the study discusses advantages and disadvantages of the algorithms.

The current work investigates the performance of a single-stage, bench-scale system using a spray dryer to treat produced water. The produced water is generated in three large reservoirs of Ahvaz, Maroon, and Mansouri fields, which have different compositions but the same high total dissolved solids (TDS) and total organic carbon (TOC). The results of this study indicate that the newly developed bench scale rig is able to reduce the amount of TDS in the water produced in Ahvaz, Maroon, and Mansouri reservoirs to 98.78, 98.65, and 98.90, and TOC decreases the three types of the produced water to zero. Investigating the effect of independent parameters on the performance of this system using response surface methodology shows that the most effective parameters affecting the efficiency of the produced water treatment system are the entering carrier gas temperature (TGIT), the flow rate of the produced water (QL), the carrier gas flow rate entering the spray dryer (QG), and the atomizer pore size (d). Additionally, the optimal conditions are obtained as follows: TGIT = 113.7 °C, QL = 20.8 cc/min, QG = 59.9 m3/hr., and d = 0.03 mm.

Treatment of oily wastewater such as the produced water (PW) generated by oil and gas industries remains a pressing challenge. To mitigate this problem, a new ceramic membrane was fabricated for the efficient separation of an oil-in-water emulsion. The key component in this membrane is the titanium carbide (TiC) selective layer which was affixed onto an alumina ceramic support through interfacial polymerization (IP). The merits of the fabricated TiC@Alumina membrane were thoroughly characterized by different techniques and tested for the separation of oil/water (O/W) emulsion. A permeate flux of 591 LMH was achieved at a pressure of 8 bar. The membrane achieved a separation efficiency of > 99 % for all of the tested O/W emulsions (125 ppm, 250 ppm, and 500 ppm). The long-term stability test revealed that the composite membrane maintained excellent separation efficiency (>99 %) for 360 min.

Microbiologically influenced corrosion (MIC) or biocorrosion is a complex biological and physicochemical process, Strategies for monitoring MIC are frequently based on microbial cultivation methods, while microbiological molecular methods (MMM) are not well-established in the oil industry in Brazil. Thus, there is a high demand for the development of effective protocols for monitoring biocorrosion with MMM. The main aim of our study was to analyze the physico-chemi- cal features of microbial communities occurring in produced water (PW) and in enrichment cultures in oil pipelines of the petroleum industry. In order to obtain strictly comparable results, the same samples were used for both culturing and metabarcoding. PW samples displayed higher phylogenetic diversity of bacteria and archaea whereas PW enrichments cultures showed higher dominance of bacterial MIC-associated genera. All samples had a core community composed of 19 distinct genera, with MIC-associated Desulfovibrio as the dominant genus. We observed significant associations between the PW and cultured PW samples, with a greater number of associations found between the cultured sulfate-reducing bacteria (SRB) samples and the uncultured PW samples. When evaluating the correlation between the physicochemical characteristics of the environment and the microbiota of the uncultivated samples, we suggest that the occurrence of anaerobic digestion metabolism can be characterized by well-defined phases. Therefore, the detection of microorganisms in uncultured PW by metabarcoding, along with physi-cochemical characterization, can be a more efficient method compared to the culturing method, as it is a less laborious and cost-effective method for monitoring MIC microbial agents in oil industry facilities.

Improving the produced fluid yield is an effective measure for realizing the crude oil production capacity of offshore platforms. However, for offshore platforms employed in production, using the narrow space of the platform to expand the produced water treatment system is a significant problem. In this study, a highly efficient pre-treatment core tube was coupled with the main cavity and secondary cavities (MCSCs) based on a vane-type tubular separator and a cub-mother cyclone. The optimal inlet Reynolds number and processing capacity were determined according to the structure size of the MCSC, and the MCSC was applied to achieve highly efficient pre-treatment of produced water in a heavy oilfield in the Bohai Sea. The comprehensive evaluation indicators FA and FV were better than those used by current technology. When the influent oil content fluctuated around 2000 mg/L (average of 1772.81 mg/L), the oil content in the effluent was stable and below 200 mg/L (average of 106.44 mg/L), and the separation efficiency was nearly 94%. Compared to those of the current corrugated plate interceptor on the platform, the floor space was reduced by more than 60% and the separation efficiency increased by up to 65%.

This article describes the design of photo catalyst reactor for oil removing from produced water. Real produced water containing a combination of organic compounds was treated with zinc oxide nanoparticles. In this study, ultraviolet radiations were used to find the efficiency of removing the oil content from the water produced that brought from the Al-Ahdab oilfield in kut/Iraq by advanced oxidation process (AOP) using (ZnO/UV) in batch system and continuous system. In batch system were studied the effect of zinc oxide concentration (nanoparticles), time of irradiation, and pH. The highest removal rate of oil from the produced water (100%) was obtained during the following optimal conditions: ZnO NPs as catalyst = 55 mg/L, pH =3, at the time of irradiation of 90 minutes in batch experiments. In the continuous system, the effects of flowrate, number of UV-A lamp and time of reaction were studied, the results obtained were the efficiency of decomposition decreases with increasing the flow rate of solution in reactor, the maximum removal efficiency of the process (ZnO/UV) was 80% at 20 mL/min and irradiation time 120 min. In general, zinc oxide is beneficial through its high oil adsorption capacity in addition, It lowers the amount of oil in the produced water. [ABSTRACT FROM AUTHOR]

There exist numerous counts of research works on produced water. We got to know about them because they made it to publishing probably by indicating a positive or promising result. Contrarily, there exist a hundred times unpublished, unreported works on produced water; works rejected based on not yielding desirable results or not being innovative enough. We might have encountered undesirable results but to what depths and time have we committed to mining out intricate details. The world is thinking and demanding sustainability. Is it sustainable for the future of water treatment, the ease and pace at which we transition to the next chemical or treatment option? In this data-centred approach, three common chemicals, aluminium sulphate, ferrous ammonium sulphate and calcium chloride, were used to treat produced water. The collected data (both initial and final analysis) were inferentially analysed. The first statistical analysis was the testing of 2 hypotheses using the Analysis of Variance test. This was done to reveal to compare the dependence of produced water properties on two categorical variables (sample type and treatment chemicals). The second was the test for relevance: correlation and regression analyses. The laboratory experimental analysis revealed that aluminium sulphate was most suitable for the alteration of physical effluent characteristics; ferrous ammonium sulphate for salinity concerns and calcium chloride for a particular heavy metal's stability. The overall effluent characteristics indicated a greater dependency on 'sample type' than 'treatment chemicals'. Certain produced water properties relationships were highlighted and quantified for instance iron(II) and chloride ion concentrations were dependent on total solids and indicated a significance F of 0.01. [ABSTRACT FROM AUTHOR]

Understanding the geochemistry of waters produced during petroleum extraction is essential to informing the best treatment and reuse options, which can potentially be optimized for a given geologic basin. Here, we used the US Geological Survey's National Produced Waters Geochemical Database (PWGD) to determine if major ion chemistry could be used to classify accurately a produced water sample to a given geologic basin based on similarities to a given training dataset. Two datasets were derived from the PWGD: one with seven features but more samples (PWGD7), and another with nine features but fewer samples (PWGD9). The seven-feature dataset, prior to randomly generating a training and testing (i.e., validation) dataset, had 58,541 samples, 20 basins, and was classified based on total dissolved solids (TDS), bicarbonate (HCO3), Ca, Na, Cl, Mg, and sulfate (SO4). The nine-feature dataset, prior to randomly splitting into a training and testing (i.e., validation) dataset, contained 33,271 samples, 19 basins, and was classified based on TDS, HCO3, Ca, Na, Cl, Mg, SO4, pH, and specific gravity. Three supervised machine learning algorithms—Random Forest, k-Nearest Neighbors, and Naïve Bayes—were used to develop multi-class classification models to predict a basin of origin for produced waters using major ion chemistry. After training, the models were tested on three different datasets: Validation7, Validation9, and one based on data absent from the PWGD. Prediction accuracies across the models ranged from 23.5 to 73.5% when tested on the two PWGD-based datasets. A model using the Random Forest algorithm predicted most accurately compared to all other models tested. The models generally predicted basin of origin more accurately on the PWGD7-based dataset than on the PWGD9-based dataset. An additional dataset, which contained data not in the PWGD, was used to test the most accurate model; results suggest that some basins may lack geochemical diversity or may not be well described, while others may be geochemically diverse or are well described. A compelling result of this work is that a produced water basin of origin can be determined using major ions alone and, therefore, deep basinal fluid compositions may not be as variable within a given basin as previously thought. Applications include predicting the geochemistry of produced fluid prior to drilling at different intervals and assigning historical produced water data to a producing basin. [ABSTRACT FROM AUTHOR]

The cost of treatment of produced water prior to disposal forms a significant percentage of the total economic impact of pollutants in crude oil production. The treatment of produced water involves the removal of toxic compounds contained in the fluid to a level where it is considered safe before the water can be disposed, discharged or reused in the environment. Production chemicals have been identified as one of the sources through which these toxic compounds enter the produced water and therefore the need to evaluate the influence of these chemicals at their various injection rates on the quality of the produced water from the production process. This research study is a part of an on-going project on the application of environmental process engineering for pollutant reduction and energy savings in crude oil production. The study has found that the introduction of scale inhibitor, paraffin inhibitor, demulsifier, biocides and corrosion inhibitor at the rates of 10 ppm, 200 ppm, 15 ppm, 500 ppm and 10 ppm, respectively, yields a corresponding increase in the concentrations of ammonia, hydrocarbons, salinity, phosphates and nitrates in the produced water by 242%, 53%, 12.5%, 300% and -4.8%, respectively. The knowledge provided by this project will educate the oil and gas sector across the globe, aid engineers and operators understanding of produced water pollution mechanism during oil and gas production processes. The results of this research will also be useful in the design of crude oil production and produced water treatment processes in avoiding negative environmental impacts from the final effluent composition of produced water. [ABSTRACT FROM AUTHOR]

The water produced (PW) by the petroleum industry is a potential contaminant to aquatic biota, due to its complex mixture that may contain polycyclic aromatic hydrocarbons (PAHs), organic chemical compounds, including benzene, toluene, ethylbenzene and xylene (BTEX), metals and other components that are known to be toxic. The aim of this investigation was to examine the acute toxicity produced by a PW sample in aquatic organisms Vibrio fischeri and Daphnia similis prior to and after 4 treatments using advanced oxidative processes such as photocatalysis, photoelectrocatalysis, ozonation and photoelectrocatalytic ozonation. Data demonstrated that exposure to PW was toxic to both organisms, as evidenced by reduced luminescence in bacterium Vibrio fischeri and induced immobility in Daphnia similis. After treatment of PW with 4 different techniques, the PW remained toxic for both tested organisms. However, photoelectrocatalysis was more efficient in decreasing toxicity attributed to PW sample. Therefore, data demonstrate the importance of treating PW for later disposal in the environment in order to mitigate ecotoxicological impacts. Further photoelectrocatalysis appeared to be a promising tool for treating PW samples prior to disposal and exposure of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Activities and/or processes in different segments of the petroleum industry, including upstream and downstream, generate aqueous waste streams containing oil and various contaminants that require treatment/purification before release/reuse. Nanofiltration (NF) technology has been approved as an efficient technology for treating wastewater streams from the petroleum industry. The primary critical issues in an NF treatment process can be listed as mitigation of membrane fouling; selection of appropriate pre-treatment process; and selection of a suitable, cost-effective, non-hazardous cleaning strategy. In this study, NF separation mechanisms, membrane fabrication/modification, effective factors on NF performance, and fouling are briefly reviewed. Then, a summary of recent NF treatment studies on various petroleum wastewaters and performance evaluation is presented. Finally, based on the gaps identified in the field, the conclusions and future perspectives are discussed. [ABSTRACT FROM AUTHOR]

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Produced water, a mixture of inorganic and organic components, comprises the largest effluent stream from oil and gas activities. The removal of contaminants from this wastewater is receiving special attention of the researchers since most of them are persistent and difficult to remove with simple techniques. Several technologies from conventional to advanced oxidation processes have been employed to treat produced water. However, the achievement of greater efficiency may be conditioned to a combination of different wastewater treatment techniques. Hereupon, the present paper discusses three important aspects regarding produced water treatment: analytical methods used for characterization, relevant aspects regarding photochemical systems used for advanced oxidation processes, and combined techniques for treating oil field wastewaters. Analytical methods employed for the quantification of the main species contained in produced water are presented for a proper characterization. Photochemical aspects of the reaction systems such as operating conditions, types of irradiation sources, and technical details of reactors are also addressed. Finally, research papers concerning combined treatment techniques are discussed focusing on the essential contributions. Thus, this manuscript aims to assist in the development of novel techniques and the improvement of produced water treatment to obtain a high-quality treated effluent and reduce environmental impacts. [ABSTRACT FROM AUTHOR]

Sarvestan and Saadatabad oilfields produce more than 140 bbl/day of wastewater due to oil processing. Due to environmental issues, the produced water is injected into a disposal well through a pipeline with a diameter of 8 inch and a length of 5 km. Formation of inorganic scale may accelerate the need for frequent reservoir acid stimulation, restrict flow path, and generally add unpredicted costs for water injection operations. This study predicts scaling tendency and examines scale precipitation at different pressures, temperature, and mixing ratios of injection wastewater with formation water in Sarvestan and Saadatabad oilfields. The experimentally measured chemical analysis of the injection water and formation water was used to estimate the amount, type, and composition of scale due to mixing and changes in thermodynamic conditions. Scaling tendency values for eight types of scale, namely CaCO3 (calcite), CaSO4 (anhydrite), CaSO4.2H2O (gypsum), FeCO3 (siderite), Fe(OH)2 (amorphous), NaCl (halite), Mg(OH)2 (pyrochroite), and KCl (sylvite), were investigated by commercial software packages OLI ScaleChem and StimCADE. The results show that the significant scales are CaCO3 and FeCO3 formed in Sarvestan and Saadatabad oilfields. The formation of these scales can lead to severe problems, such as disrupting equipment and decreasing production; thus, it is necessary to predict all types of scales before forming. It allows design and planning for chemical inhibitor treatment and prediction of injectivity problems and acid stimulation. [ABSTRACT FROM AUTHOR]

Produced water is a large amount of water wasted throughout the crude oil extraction process, it's a mixture of the well's deposition water and the water of oil wells extraction water. Produced water contains oil, suspended solids and dissolves solid. This study tested produced water collected from Alahdab oilfield/middle oil company for oil content and suspended solid contamination using chemical precipitation and coagulation-flocculation for reinjection and environmental considerations. Coagulation/flocculation is a common method used as primary purification to oily wastewater treatment due to its usability, performance, and low cost. Coagulant experimental was completed by A jar test device, additives of ferric sulfate and aluminium sulfate were in a range about (40 10) ppm, as well as polyelectrolyte-(polyacrylamide) as an additional flocculent in the range (1.5-3) ppm. The results show that ferric sulfate was more efficient at removing turbidity than aluminium sulfate under the same conditions, with the best removal of turbidity at dose concentration 30 ppm of Ferric sulfate and a flocculent dose concentration of 2.5 ppm of polyacrylamide, also with oil content decreasing from 396.71 ppm to 53.56 ppm. [ABSTRACT FROM AUTHOR]

Abstract Biocorrosion is the main process that causes pipeline damages and losses in the oil industry. The objective of this work was to investigate the influence of biofilm forming microorganisms on the biocorrosion of X80 steel exposed in produced water through microbiological characterization, film and biofilm analysis by optical microscopy and scanning electron microscopy, weight loss and surface analysis by laser confocal microscopy. Changes in produced water after 360 days were attributed to planktonic cells, temperature conditions, contact with air, photo-oxidation, biodegradation, and seasonality. The total aerobic bacteria presented sessile cell concentration of 7.39 x 104 CFU/cm2, while the other investigated groups showed lower concentrations. The micrography of the film showed salt crystals, whereas in the biofilm microorganisms, exopolysaccharides and corrosion products were observed. Weight loss after 360 days for the abiotic and biotic systems was 0.0222 g/cm2 and 0.3039 g/cm2, respectively, showing that microorganisms accentuated the corrosion of X80 steel.

Hydraulic fracturing utilizes pressurized liquid typically consisting of water, proppants, and a multitude of chemical additives, in order to fracture petroliferous strata to extract natural gas and oil. In this process, a vast amount of wastewater is produced. This water is heavily contaminated, which renders it unusable outside of direct reuse, without extensive treatment being performed. Typically, various sophisticated analytical techniques are involved in the characterization of both waste and treated waters, increasing the cost and the complexity of the management efforts. The article discusses the constituents found in oilfield wastewater, the methods used to identify and quantify these constituents, and the present management methods. Additionally, we introduce total organic carbon and conductivity analyses as surrogate measurements of overall water quality. Total organic carbon and conductivity are established bulk measurements, which can be used to facilitate rapid decisions regarding the treatment and greater utilization of flowback and produced oilfield wastes. The application of the proposed surrogates could be used to streamline the current myriad of complex and expensive measurements. This would improve operational efficiency with respect to wastewater management in the energy sector.

The geochemical characteristics of water produced from coalbed methane (CBM) wells contain rich information about the associated geology, environment, and production. This study was conducted in the Southern Qinshui Basin, where produced water samples were collected from 10 typical CBM wells and their ionic compositions and water quality parameters were tested. The differences in the chemical characteristics of the produced water between different producing coal seams and between single-seam production wells (SPWs) and multi-seam co-production wells (MCWs) were compared, and the geochemical formation process of the produced water was revealed. The following conclusions were obtained: (1) the water produced samples that were mainly Na-HCO3-type and were generally weakly alkaline and moderately mineralized. The water produced from No. 15 coal seam was more enriched in SO4, Ca, and Mg compared to that of No. 3 coal seam, and the variations were more intense, reflecting a more complex water chemistry formation. (2) The ionic data of the water produced from MCWs do not lie between the coal seams of SPWs, nor do they satisfy the linear relationship between the ionic compositions of SPWs, reflecting the differences in the water sources between MCWs and SPWs. Water from MCWs tends to communicate with active water sources outside the coal seams, and the produced water contains small amounts of Cl and total dissolved solids, thus inhibiting the pressure reduction efficiency and limiting the effect of CBM co-production. (3) Based on a principal component analysis of the ionic compositions, two characteristic components were extracted, and these represented two types of hydrochemical formation processes. The first type is pyrite oxidation and carbonate dissolution, and its opposite represents sulfate reduction. The second type reflects the groundwater retention and confinement characteristics, and its opposite represents active groundwater or stronger recharge conditions. (4) A geochemical formation model of the water produced from CBM wells in the study area was constructed. Cation exchange adsorption and sulfate reduction were found to be the main water–rock interactions in the coal measure, and they determine the overall water quality of the produced water. Recharge has a relatively significant influence on water produced from MCWs. Pyrite oxidation exists in the water produced from No. 15 coal seam of the Taiyuan Formation, and the higher sulfur content in the coal contributes to this reaction. The results of the study will assist in deepening our understanding of the geochemical formation mechanisms of water produced from CBM wells, and they provide the main reasons for the poor CBM co-production effect from the Shanxi and Taiyuan Formations.

Fiber‐reinforced polymer (FRP) composites are exposed to various corrosive media during their service life, which adversely affects their material properties. Here, a novel approach is developed to investigate the long‐term performance of glass FRP composite laminate immersed in produced water generated in oil fields. This is achieved by monitoring the internal hygroscopic strain developed over the aging time using embedded fiber Bragg grating sensor. Composite material strength reduction over the immersion time is evaluated by conducting destructive mechanical tests at regular intervals, and the mechanism of property degradation is established. It is observed that property degradation follows first‐order kinetics and absorption of produced water medium obeys dual‐sorption diffusion kinetics. Moreover, the strain developed within the composite laminate is formulated by considering the unified influence of swelling and chemical degradation. The predicted strain closely interprets the experimentally recorded strain. This work proves that the strain measurement is an effective nondestructive technique to estimate the property of FRP composite laminates on a real‐time basis. [ABSTRACT FROM AUTHOR]

In this study, the performance and efficiency of electrocoagulation (EC), electro-activation of persulfate (EC/PS), and thermal activated-EC/PS for the treatment of two real produced water (PW) samples using iron electrodes were studied. To optimize and find out the effect of operating conditions on the different responses for EC and EC/PS, response surface methodology (RSM) was implemented. The results showed that EC process had considerable performance in the removal of H 2 S (96 %), oil and grease (O&G) (98–99 %), turbidity (91–97 %), phosphate phosphors (94 %), and heavy metals (92 %). EC/PS was introduced as an effective and a compact method for the removal of soluble hydrocarbons and nitrogen-ammonium (N-NH 4 +). The results indicated that at the current density of 35 A/m2, PS of 30 mM, reaction time of 30 min, N-NH 4 + and chemical oxygen demand (COD) removal efficiency increased to 37 % and 71–94 %, respectively. To further increase the ammonia removal, EC/PS was integrated into thermal-PS activation at 65 °C, and the results showed that the ammonia removal by thermal/EC/PS reached about 69 %. According to gas chromatography/mass spectrometry (GC/MS), EC/PS was able to effectively eliminate most of the hydrocarbons. Moreover, a new kinetic model based on a novel algorithm and the main reactions occurring during EC/PS was developed to predict the COD removal efficiency, and the results indicated that it could predict COD removal efficiency with the acceptable accuracy. The estimated operating costs and energy consumption for EC/PS demonstrated that this process was more economical and efficient than other advanced oxidation processes (AOPs). [ABSTRACT FROM AUTHOR]

In the present study, high surface area boehmite nanopowder was recovered from aluminum cans waste. The sodium aluminate solution was first prepared by dissolving aluminum cans in NaOH solution and then, H2O2 solution was added to precipitate boehmite. The prepared boehmite was characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption–desorption techniques. The thermal stability of the boehmite sample was investigated using thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. The feasibility of using the prepared boehmite powder as a new low-cost adsorbent for the treatment of oilfield produced water was investigated. For comparison, commercial activated carbon was used for the treatment of the produced water under the same conditions. The efficiency of both of boehmite and activated carbon in the treatment of produced water was determined by monitoring the values of a number of pollution indicators [i.e. turbidity, sulfides, sulfates, total organic carbon (TOC), total petroleum hydrocarbon (TPH), and chemical oxygen demand (COD)] before and after the treatment. The boehmite powder showed very good efficiency in the treatment of the produced water, which is very close to that of commercial activated carbon under the same conditions. The effect of adsorbent dose, treatment time, and pH of the media on the adsorption efficiency of both of boehmite and activated carbon was examined at room temperature using chemical oxygen demand as a pollution indicator. The maximum capacity for COD reduction was 69.6% for boehmite and 83.5% for activated carbon at 40 g/l adsorbent dosage, pH7, and 24-h contact time. [ABSTRACT FROM AUTHOR]

In view of the existing problems of many treatment processes and large mud production in the cryogenic distillation station of Yuanba Gas Field, it is planned to introduce electrochemical oxidation method for mining. The effluent is pretreated to remove ammonia nitrogen and reduce organic content. Optimized the current intensity and electrolysis time in the electrochemical oxidation reaction through a small test between. The results show that after the hardness of the produced water is removed, when the electrolysis current is 1200A and the reaction time is 30min, the ammonia nitrogen removal rate can reach 100%, while effectively reducing the organic content of wastewater. At this time, the cost of water treatment per ton is 7.56 yuan. Combined with the actual situation of the cryogenic distillation station, pilot test The process of "clarification and softening + electrolysis of ammonia nitrogen + reverse osmosis + MVR evaporation" is adopted to shorten the treatment process and effectively reduce the disposal of chemicals and sludge Cost, providing theoretical and process design support for the subsequent new resource recycling station. [ABSTRACT FROM AUTHOR]

Sorption and desorption of 226Ra from produced water with oil production on walnut shell media were investigated using batch-type and column-type techniques. The results showed that 226Ra is completely adsorbed onto the walnut shell media with equilibrium time of approximately 15 min provided that the concentration of competing ions are low. Removal efficiency of 226Ra from produced water by walnut shell media depends mainly on pH and concentration of associated ions such as Na+, Ca+2, Ba+2 and Sr+2; removal efficiency decreased when concentrations increase. Adsorbed 226Ra on walnut shell filters can be easily desorbed from walnut shell media using NaCl solution (0.5 mol L−1 provided that adsorbed oil by shells is first removed; oil can be easily removed by washing the walnuts shell filters using FeSO4 and H2O2 solution. The method was applied to several walnut shell filters collected from the oilfield water treatment plants and the results proved the effectiveness of the applied method. [ABSTRACT FROM AUTHOR]

Currently, the treatment of organic pollution in oilfield-produced water has been increasingly considered. In this work, a catalyst of sodium citrate-Cu(II) complex supported on bentonite (B) (B@Cu(II)L) was prepared to appraise its capacity of catalytic degrading for hydroxypropyl guar gum (HPGG), polyacrylamide (PAM), and carboxymethyl cellulose (CMC) in oilfield wastewater. Significant effect parameters considered of diverse temperature, H2O2 concentration, B@Cu(II)L dosage, and pH value in heterogeneous Fenton-like course were investigated, respectively. The results show that B@Cu(II)L exhibits high catalytic performance for the degradation of HPGG in a wide pH range of 7.0–13.0. The viscosity of HPGG can be reduced effectively with the 20.0% H2O2 (mass ratio to HPGG) and 10.0% B@Cu(II)L (mass ratio to H2O2). The removal rate for chemical oxygen demand (COD) of HPGG, PAM, and CMC reaches to 96.1%, 94.1%, and 95.0%, respectively, within 240 min under the optimized conditions, and the COD of an oilfield wastewater sample can be removed by 93.0% under the same condition. [ABSTRACT FROM AUTHOR]

[Display omitted] Large volumes of water become contaminated with hydrocarbons, surfactants, salts and other chemical agents during Oil & Gas exploration activities, resulting in a complex wastewater stream known as produced water (PW). Nanofiltration (NF) membranes are a promising alternative for the treatment of PW to facilitate its re-use. Unfortunately, membrane fouling still represents a major obstacle. In the present work, we investigate the effect of surface chemistry on fouling of NF membranes based on polyelectrolyte multilayers (PEM), during the treatment of artificial produced water. To this end, oil-in-water (O/W) emulsions stabilized with four different surfactants (anionic, cationic, zwitterionic and non-ionic) were treated with PEM-based NF membranes having the same multilayer, but different top layer polymer chemistry: crosslinked poly(allylamine hydrochloride) (PAH, nearly uncharged), poly(sodium 4-styrene sulfonate) (PSS, strongly negative), poly(sulfobetaine methacrylate-co-acrylic acid) (PSBMA-co-AA, zwitterionic) and Nafion (negative and hydrophobic). First, we study the adsorption of the four surfactants for the four different surfaces on model interfaces. Second, we study fouling by artificial produced water stabilized by the same surfactants on PEM-based hollow fiber NF membranes characterized by the same multilayer of our model surfaces. Third, we study fouling of the same surfactants solution but without oil. Very high oil retention (>99%) was observed when filtering all the O/W emulsions, while the physicochemical interactions between the multilayer and the surfactants determined the extent of fouling as well as the surfactant retention. Unexpectedly, our results show that fouling of PEM-based NF membranes, during PW treatment, is mainly due to membrane active layer fouling caused by surfactant uptake inside of the PEM coating, rather than due to cake layer formation. Indeed, it is not the surface chemistry of the membrane that determines the extent of fouling, but the surfactant interaction with the bulk of the PEM. A denser multilayer, that would stop these molecules, would benefit PW treatment by decreasing fouling issues, as would the use of slightly more bulky surfactants that cannot penetrate the PEM. [ABSTRACT FROM AUTHOR]

Shale gas-produced water (PW), the waste fluid generated during gas production, contains a large number of organic contaminants and high salinity matrix. Previous studies generally focused on the end-of-pipe treatment of the PW and ignored the early collection process. In this study, the transformation of the molecular composition and microbial community structure of the PW in the transportation and storage process (i.e., from the gas–liquid separator to the storage tank) were investigated. As the PW was transported from the gas–liquid separator to the portable storage tank, the dissolved organic matter (DOM) showed greater saturation, less oxidation, and lower polarity. DOMs with high O/C and low H/C ratios (numbers of oxygen and hydrogen divided by numbers of carbon) were eliminated, which may be due to precipitation or adsorption by the solids suspended in the PW. The values of double-bond equivalent (DBE), DBE/C (DBE divided by the number of carbon), and aromatic index (AI) decreased, likely because of the microbial degradation of aromatic compounds. The PW in the gas–liquid separator presented a lower biodiversity than that in the storage tank. The microbial community in the storage tank showed the coexistence of anaerobes and aerobes. Genera related to biocorrosion and souring were detected in the two facilities, thus indicating the necessity of more efficient anticorrosion strategies. This study helps to enhance the understanding of the environmental behavior of PW during shale gas collection and provides a scientific reference for the design and formulation of efficient transportation and storage strategies to prevent and control the environmental risk of shale gas-derived PW. [ABSTRACT FROM AUTHOR]

The growing global concern with water resources management has driven the search for more effective treatments for industrial effluents. The produced water is inserted in this scenario as one of the largest effluents generated by the oil industry. Besides, it cannot be discarded or reused without proper treatment due to its complex and toxic chemical composition. A bibliometric study was performed on the Scopus database from inception to 2020 in order to map the evolution of scientific publications related to the advanced oxidation processes based on reactions with ozone and Fenton's reagent. The results reinforced the efficiency of such processes for treating the produced water and the increasing of publications in the last few years, although the first document appeared only in 1995. China was the leading country in this research area, followed by Brazil and the USA. The most relevant journals were the Environmental Science & Technology and the Journal of Hazardous Materials. The research trends pointed out that the use of Fenton, photo-Fenton, and ozonation processes has been associated with other treatment methods to enhance the removal of contaminants in the produced water samples. However, the documents selected revealed the limitation on these processes due to the high costs with energy consumption. The present study can help other researchers mainly due to the few studies in this area, which demonstrates the importance of this prospection to support the development and application of advanced oxidation processes on produced water treatments. [ABSTRACT FROM AUTHOR]

In this work, activated carbon, zeolite, silica gel, and mixed adsorbents (activated carbon and silica gel) were used for adsorption of oil and chemical oxygen demand (COD) from produced water by experiments of adsorption (continuous fixed-bed column). Two types of activated carbon (powdered and granular) were utilized. The effects of operational parameters, such as flow rate (1.25–3.15 mL/min), oil concentration (40–1,000 ppm), and COD concentration (1,350–28,500 ppm), on the performance of the column were studied. Also, two kinetics models (Thomas and Yoon– Nelson models) were applied to predict the breakthrough curve and calculate the distinguishing parameters of the column that are beneficial for a process design. The results reveal that Thomas kinetic model was suitable for the adsorption of oil and COD on all types of adsorbents. Also, the removal of pollutants increased with a decrease in flow rate and concentration. The highest removal of oil and COD were obtained (83.62% and 78.81%) by mixed adsorbents, (72.98% and 69.5%) by powdered activated carbon, (67.8% and 64.74%) by silica gel, (64.87% and 60.94%) by granular activated carbon, (58.58% and 52.49%) by zeolite at a flow rate (1.25 mL/min), adsorbent dose (0.5 g) oil concentration (40 ppm), and COD (1,350 ppm) bed height (2 cm); the highest adsorption capacity was 108.38 mg/g for oil and 96.74 mg/g for COD by mixed adsorbents. As well, the results illustrate that the highest removal of pollutants by mixed adsorbents, and least removal of pollutants by zeolite. Therefore, the results suggest that mixed adsorbents (activated carbon and silica gel) can be an effective adsorbent for the removal of pollutants from produced water. [ABSTRACT FROM AUTHOR]

Large amounts of produced water are extracted by the Oil and Gas energy sector since the industrial revolution. This available water, often salty, can be used to dilute liquid digestate from the anaerobic digestion process, a promising source of nutrients for microalgae cultivation. The study investigates the growth of halotolerant microalgae and their associated bacteria in column photobioreactors (PBRs) and open raceway pond (RWP), to treat industrial wastewaters while producing biomass for energy valorisation. Microalgae were cultured in mixtures of saline artificial produced water (7–44 %v/v), liquid digestate (5 %v/v using PBRs, 29–63 %v/v using RWP) and seawater. Nannochloropsis oceanica and Tetraselmis suecica strains were firstly cultivated in 70 L PBRs in indoor conditions for 3 months and later in 1.1 m3 RWP operated in outdoor conditions for 5 months in spring-summer period. In PBRs, average productivity was 9.0 ± 4.2 gVSS·m−2·d−1 (102–153 mgVSS·L−1·d−1), with daily removal efficiencies for chemical oxygen demand, nitrogen and phosphorous up to 61.8, 31.6 and 97.2 %, respectively. In RWP, strong changes in the microalgae populations were observed. Productivity was 6.7 ± 5.2 gVSS·m−2·d−1 (30 ± 23 mgVSS·L−1·d−1), with daily removal efficiencies for chemical oxygen demand, nitrogen and phosphorous up to 48.4, 44.4 and 88.1 %, respectively. In parallel with the production of microalgae, a nitrifying microbial population grew in the RWP despite the high salinity (70 g L−1). Over these periods of several months, microalgae production was maintained using a culture medium containing high salt concentration, metals and harmful aromatic compounds. [Display omitted] • Halotolerant microalgae were cultivated in column photobioreactors and raceway pond. • Similar areal productivities (7-9 gVSS·m−2·d−1) were obtained using both systems. • Up to 62% COD, 32% nitrogen and 98% phosphorous removed using column photobioreactors. • Up to 48% COD, 44% nitrogen and 88% phosphorous removed using raceway pond. • High nitrification was observed despite the high salinity of the culture medium. [ABSTRACT FROM AUTHOR]

Green chemistry has brought to the spotlight new sets of principles for reducing or eliminating hazardous substances in the synthesis and application of processes and products. Despite its noteworthy growth, this area still lacks studies that compare the potential of greener materials with those conventionally synthesized. Herein, novel materials based on chitosan and reduced graphene oxide were developed via the green (G-Fe/CS/rGO) and conventional routes (C–Fe/CS/rGO). Eucalyptus leaves extract and proanthocyanidin were used in the green approach as reducing/capping and crosslinking agents, respectively, replacing hydrazine and glutaraldehyde, commonly used in conventional synthesis. In addition, carbon nanotubes were also modified with plant extracts. The effect of different rGO contents was evaluated through adsorptive assays. Furthermore, the adsorption potential of C–Fe/CS/rGO, G-Fe/CS/rGO and green CNTs. Priority "Produced Water" contaminants of such as anthracene (ANT), fluoranthene (FLT), phenol (PE), and cyclohexane carboxylic acid (CHA) were used as target contaminants. The best materials were characterized by XRD, FTIR, SEM-EDS and Zeta potential analyses. C–Fe/CS/rGO-3% removed 86.6%, 89.3%, 13.4%, and 33.6%, G-Fe/CS/rGO-7% removed 83.2%, 83.9%, 6.7% and 30.3 % and CNT-E 82.9%, 97.6%, 10.7% and 12.4% of ANT, FLT, PE, and CHA, respectively. Green and conventional beads showed similar performance, indicating the promising use of green synthesis. CNT-E, which demonstrated the best adsorption capacity, was used in reuse assays to assess its feasibility. The material kept FLT removal above 85% after four consecutive adsorption-desorption cycles. Molecular modelling analysis indicated that CHA has greater stability, followed by PE, FLT and ANT, agreeing with the experimental results. [Display omitted] • Synthesis of carbon-based materials through conventional and green methods. • Characterization analyses indicated the feasibility of green methodologies. • Comparison between adsorption capacities of green and conventional materials. • Molecular modelling indicated that ANT and FLT are the most reactive contaminants. • C–Fe/CS/rGO-3%, G-Fe/CS/rGO-7% and CNT-E removed > 86%; > 83%; > 83% of ANT and FLT, respectively. [ABSTRACT FROM AUTHOR]