Use of Reverse Electrodialysis to Harvest Salinity Gradient Energy from Oilfield Produced Water

Nitrate addition to oil field waters stops the biogenic formation of sulfide because the activities of nitrate-reducing bacteria (NRB) suppress the activities of sulfate-reducing bacteria (SRB). In general, there are two types of NRB - the heterotrophic NRB and the chemolithotrophic NRB. Within the latter group are the nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB). To date, no study has specifically addressed the roles of these different NRB in controlling sulfide concentrations in oil field produced waters. This study used different culture media to selectively enumerate heterotrophic NRB and NR-SOB by most probable number (MPN) methods. Produced waters from three sulfide-containing western Canadian oil fields were amended with nitrate as an electron acceptor, but no exogenous electron donor was added to the serum bottle microcosms. Changes in the chemical and microbiological characteristics of the produced waters were monitored during incubation at 21 degrees C. In less than 4 days, the sulfide was removed from the waters from two of the oil fields (designated P and C), whereas nearly 27 days were required for sulfide removal from the water from the third oil field (designated N). Nitrate addition stimulated large increases in the number of the heterotrophic NRB and NR-SOB in the waters from oil fields P and C, but only the NR-SOB were stimulated in the water from oil field N. These data suggest that stimulation of the heterotrophic NRB is required for rapid removal of sulfide from oil field-produced waters.

The selection of an apt technology for the treatment of Oilfield Produced Water (OFPW) depends mainly on the quality of OFPW and methods of pre-and post-treatment processes. The most challenging part of the OFPW treatment process is the removal of Suspended Solid (SS), Oil & Grease (O&G) and dissolved organics. SS and O&G pose an acute problem to the membrane filtration system by fouling the membrane surface which increases operation & maintenance costs and decreases the life of the membrane. Fouling of the membrane surface is mainly attributed to the presence of low molecular weight aromatic compounds and naphthenic acids in the suspended and dissolved organic compounds. Thus, the removal of these suspended and dissolved organic compounds before membrane filtration proffers a challenge to the researchers. In this research, bioremediation process has been applied to remove the organic compounds and the performance and fouling behaviour of hollow fibre Microfiltration (MF), Ultrafiltration (UF) and Nanofiltration (NF) membranes after the bioremediation process has been analyzed in detail. The level of toxicity was determined by comparing the pollutants with the safe discharge limit for disposal into the environment set by Central Pollution Control Board (CPCB), India. The research presents its novelty by using a hydrocarbon-degrading bacteria, Pseudomonas aeruginosa for the Reduction of Organic Loads (ROL) from OFPW of Moran oil field of Upper Assam as a pre-treatment to membrane filtration. The Total Sum Corrected Area (TSCA) method through chromatographic analyses was used for this. The organic loads removal from OFPW by the TSCA method was found to be 67–100%, 100% and 100% after 7, 14 and 21 days of bioremediation respectively. The major parameters in feed OFPW of Moran oil field were found to be pH (7.5–9.3), Total Dissolved Solid (TDS) (1.79–4.75) ppt, O&G (1.78–2.8) ppt, Salinity (2.94–6.98) ppt, Chloride (Cl−) (1.6–3.86) ppt, Bicarbonate (HCO3−) (2.89–4.03) ppt. It was observed that the ranges of pollutants removal by NF was highest such as TDS (26–86%), salinity (81–86%), turbidity (78–94%), hardness (67–75%), O&G (96–99%), Cl− (80–89%) and HCO3− (95–97%).

The combination of ET Ventures' ET #1 and granular activated carbon consistently and effectively removed hydrocarbons from Tensleep formation produced water in a 24-hour test at Teapot Dome oil field. Specific findings are that ET #1:–Reduced Total Petroleum Hydrocarbon (EPA Method 418.1) to non-detectable levels.–Reduced Oil and Grease (EPA Method 413.2) to non-detectable levels.–Reduced soluble hydrocarbons: Benzene, Ethylbenzene Toluene, and Xylene (BTEX-EPA method 8020) to barely detectable levels. BTEX was below detectable limits after the combination of ET #1 and granular activated carbon. Introduction This report describes the results of a test conducted at the Rocky Mountain Oilfield Testing Center (RMOTC) of a product manufactured and marketed by ET Ventures, L.L.C. This product, ET #1, is designed to adsorb hydrocarbons from wastewater. The test conducted at RMOTC was intended to document the ability of ET #1 to:–Adsorb a relatively large quantity of hydrocarbons from oilfield produced waters carrying a free oil sheen.–Tolerate the wide variations in hydrocarbon concentrations typical of oilfield operations.–Adsorb soluble hydrocarbons in the BTEX family under these same circumstances. A 24-hour test was designed in which produced water from the Tensleep formation was flowed through a three-stage treatment system composed of two stages containing ET #1 and a final polishing stage containing granular activated carbon (GAC). Product Description ET #1 is a product generally referred to as a polymer modified bentonite or an organoclay. This group of materials is manufactured by binding an amine polymer onto bentonite clay and drying it in a granular form. The polymer binds to the bentonite's ionic surfaces and converts the clay from a hydratable form to an oil-wet, hydrocarbon adsorbent material. Other clays are also used for the manufacture of organoclay, depending on the application and location of mineral deposits. Organoclay is commonly used in the upstream sector of the petroleum industry for removing hydrocarbons from refinery process water, but it has seen little use in petroleum production. Many other industries also use it, including shipping and dockside servicing, carwashes, and others dealing with an oily wastewater stream. Organoclays have also been tested for treating ground and surface water for other organic chemicals such as PCBs and pesticides. Present and Future Constraints on Oilfield Produced Water. Oilfield produced water is an important source of surface water in the arid western U.S. The discharge of produced water is permitted under the National Pollutant Discharge Elimination System (NPDES), which may be administered by the U.S. E.P.A. or by a state program. In addition, other state and federal programs come into play to generally prohibit the presence of a free oil sheen or staining of the shoreline of surface impoundments. Netting may also be required over surface impoundments in order to protect migratory birds from hydrocarbon contamination. P. 137^

This study investigated the application of the crystallization process for oilfield produced water from the East Baghdad oilfield affiliated to the Midland Oil Company (Iraq). Zero liquid discharge system (ZLD) consists of several parts such as oil skimming, coagulation/flocculation, forward osmosis, and crystallization, the crystallization process is a final part of a zero liquid discharge system. The laboratory-scale simple evaporation system was used to evaluate the performance of the crystallization process. In this work, sodium chloride solution and East Baghdad oilfield produced water were used as a feed solution with a concentration of 177 and 220 g/l. The impact of temperature (70, 80, and 90 °C), mixing speed (300, 400, and 500 rpm), feed concentration (177 and 220 g/l), and time (0.5-9.5 h) on the crystallization performance for oilfield produced water treatment were investigated on evaporation rate and recovery. The recovery increased with increasing temperature and mixing speed while decreasing with an increase in feed concentration. Pure water and salts were recovered from the concentrated produced water, the recovery of pure water at 80 °C, 400 rpm, and 220 g/l feed concentration was 82.22 and 81.35% after 5.5 h for NaCl solution (i.e., simulated oilfield produced water) and oilfield produced water, respectively.

Comparison of two electrodialysis stacks having different ion exchange and bipolar membranes for simultaneous separation of boron and lithium from aqueous solution

Oilfield produced water assessment from onshore treatment facilities in Niger Delta: Water quality susceptibility and suitability for soil irrigation

ICP-AES method can be used to determine multiple metallic elements simultaneously, and has the advantages of high sensitivity, good repeatability and high accuracy. In the paper, the detection limit of iron content was determined by stepwise dilution method. The influence of the cationic concentration on the determination of iron element was studied, and the matrix matching method was proposed to eliminate the influence. The results show that, the determination limit of Iron element is 0.01 mg·L-1. Because the other cationic content is several times or even tens of times as much as iron ions, it has a great influence on the determination results of Iron element. The effects of cationic concentration can be effectively eliminated by establishing a standard curve using matrix matching. After digestion pretreatment on the oil and gas field produce water, The standard adding recovery rate was between 95% and 105%, and the RSD is less than 4%. Compare this method with o-phenanthroline spectrophotometry, its relative error is within 5%. Therefore, ICP-AES method can fully meet the requirements of determination of iron content in oil field produce water, and greatly improves the efficiency and accuracy of the laboratory analysis of oil and as field wastewater.

Light-Enhanced Blue Energy Generation Using MoS2 Nanopores

Salinity gradient energy conversion by custom-made interpolymer ion exchange membranes utilized in reverse electrodialysis system

Problem Statement. Today, humanity is in search of new sources of energy to make the economy more sustainable, as well as the need for a transition to energy that works on the principles of Carbon-Free Technology. For the Black Sea, this is expressed in the desire for successful implementation of the program Blue Growth Accelerator, which is aimed at the introduction of innovative technologies and alternative energy sources in the energy sector of the Black Sea countries, for the development of the "Blue Economy" and the achievement of its healthy, productive and sustainable state. Salinity gradient power (SGP) is one of the new renewable energy sources. The most studied methods for obtaining SGP energy are technologies based on: Reverse Electrodialysis and Pressure Retarded Osmosis. The interaction of fresh and salt water can provide, in fact, unlimited, free and clean energy. The basis for the generation of such energy is the so-called salinity gradient that occurs when two types of water are mixed. After decades of work and numerous experiments, scientists have developed a way to use the energy of the salinity gradient to generate electricity. This type of electricity is also called "Blue Energy" by association with the color of mixing freshwater and salt water when rivers flow into the ocean. Places (estuaries or deltas), where rivers flow into the oceans and seas, have a truly enormous energy potential. The aim of this study is to identify sites in the northwestern Black Sea region with the necessary conditions for the development of Salinity Gradient Power energy, as well as to assess their potential using the example of estimating the maximum theoretical power of the Pressure Retarded Osmosis process. Research Methodology. In a PRO system, the less concentrated solution flows towards the more concentrated solution due to the positive osmotic pressure difference as long as this difference remains greater than the hydrostatic pressure difference. It is by this principle that osmotic power is produced. Theoretically available amount of energy released when mixing 1 m3 of saturated brine (5 mol/l NaCl solution) and 1 m3 of sea water (0.5 mol/l NaCl) at 293 K is 10 MJ. In the northwestern Black Sea region, along the coast between the Danube and Dnieper rivers, there are 21 limans (lagoons) of which some can be used to generate of Salinity Gradient Power. Results. The results of calculating the maximum net power showed that highest values obtained in the summer months, when the salinity in limans reaches its maximum and, consequently, its difference with the salinity of sea (river) water increases. Proceeding from maximum net power, obtained for the Western Sivash, where the salinity is maintained artificially at certain values, it can be seen that the annual amplitude has a smaller value, which provides more stable conditions. There are objects in the northwestern Black Sea region, in the waters of which, as soon as technologies become available, it will be possible to implement SGP projects. The Kuialnyk Liman, Sasyk- Sivash lake and Western Sivash have the most favorable conditions, where the highest power indicators are shown when using the sea water – hypersaline solution scheme, in which freshwater is not consumed.

Salinity Gradient Power (SGP), also known as Blue Energy, is gaining attention in the recent years due to its global availability and renewable nature [1,2]. SGP is based on the physico-chemical potential existing when two water streams of different salinity are mixed. The most important and well-known technology to harvest the SGP energy is the Reverse Electrodialysis (RED), which converts the blue energy into electricity through ion exchange membranes (IEMs). Usually, seawater has been targeted as high concentrated solution and river water as low concentrated solution. Nevertheless, other water bodies are possible, for example, industrial brine solutions, groundwater or treated urban wastewater streams. The presence of the non-single charge ions presents in common water streams can affect power performance due to an increase in the internal resistance of the system [3,4], and thus their effects need to be thoroughly studied.This work aims to model the RED performance providing a robust and comprehensive mathematical tool to predict power output under real conditions. The model takes into account different variables (flowrate and temperature), the RED system characteristics (effective area, thickness of both membranes and spacers and number of cell pair) as well as different scenarios in term of streams composition. In this sense, the concentration of the main compounds presents in the typical water sources was studied achieving different correlations as function of the cationic or anionic type of membrane.For this purpose, electrochemical impedance spectroscopy (EIS) technique was employed to measure the resistance of IEMs in contact with NaCl solution including mixtures of non-single charge ions (Ca2+, Mg2+, SO4 2-) in order to find suitable mathematical correlations to be integrated into the mathematical model [1]. EIS measurements were performed by placing the membranes in a nylon cell system previously submerged in the different solutions for seven days to ensure impregnation.The results obtained were validated with different experimental conditions in terms of water composition. Theoretical and experimental results fit well with errors below 5%, showing that the presence of divalent ions has a negative effect on power performance due to the increase in membrane resistance in comparison to pure NaCl solutions. Nevertheless, the maximum decay in power output, for a wide range of real scenarios studied, was not higher than 16%, which can still be considered acceptable. Acknowledgements: The authors want to acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the projects: CTQ2015-66078-R, and CTM2017-87850-R. This research is also being supported by the Project “HYLANTIC”-EAPA_204/2016, which is co-financed by the European Regional Development Fund in the framework of the Interreg Atlantic program.

Osmotic power with Pressure Retarded Osmosis: Theory, performance and trends – A review

Effect of pH in the oil field produced water on iron removal and effluent turbidity was explored by chemical precipitation and a filtration process using sodium hydroxide and porous ceramic filtration media. Mechanisms of iron removal and inhibition of electrochemical corrosion on the treatment device were discussed. The present investigation showed that influent pH had a remarkable influence on iron removal, effluent turbidity and anti- corrosion of treatment devices. Iron removal effectiveness was poor, and corrosion of the treatment device could not be inhibited atpH<7. Optimal pH was about 8.3, at which good efficiency of iron removal and anti-corrosion of treatment devices was achieved. Effluent quality met the Al quality standards of recommended indexes in SY/T5329-94. Its turbidity remained constant after 2.5 h. However, effluent turbidity at other pH readings rose gradually because of ferrous oxidation. Major removal methods for iron included gravity settling and filtration.

While oilfield produced water (PW) is one of the largest, unclaimed wastewater streams of the oil industry, it could potentially be used as a cultivation medium for microalgae. Microalgae could help with the remediation of this water while also delivering biomass that can be transformed into valuable byproducts such as biofuels. The coupling of these two purposes is expected to cut production costs of biofuels while aiding environmental protection. In this study, we compared the cultivation capacity of the marine model diatom Phaeodactylum tricornutum in media at varying salinities and in media composed of PW from two oilfields in the Central Valley of California that differed drastically in the concentration of inorganic and organic constituents. Specifically, we measured the carrying capacity of these media, the maximum growth rates of P. tricornutum, its cellular lipid accumulation capacity, and its capacity to remediate the most polluted PW source. Our study shows that P. tricornutum can successfully adjust to the tested cultivation media through processes of short-term acclimation and long-term adaptation. Furthermore, the cultivation of P. tricornutum in the most heavily polluted PW source led to significant increases in cell yield and improved photosynthetic capacity during the stationary phase, which could be attributed chiefly to the higher levels of nitrate present in this PW source. Chemical water analyses also demonstrated the capability of P. tricornutum to remediate major nutrient content and potentially harmful elements like fluorine and copper. Because P. tricornutum is amenable to advanced genetic engineering, which could be taken advantage of to improve its cultivation resilience and productivity in an economic setting, we propose this study as a step towards essential follow-up studies that will identify the genetic regulation behind its growth in oilfield PW media and its remediation of the PW constituents.

Adsorption and photocatalytic degradation of oilfield produced water by visible-light driven superhydrophobic composite of MIL-101(Cr)/Fe3O4-SiO2: Synthesis, characterization and optimization