In situ bioremediation of monoaromatic pollutants in groundwater : A review

In oil and gas industry, produced water is considered as the largest waste stream, which contains relatively higher concentration of hydrocarbons, heavy metals and other pollutants. Due to the increase in industrial activities, the generation of produced water has increased all over the world and its treatment for reuse is now important from environmental perspective. Treatment of produced water can be done through various methods including physical (membrane filtration, adsorption etc.), chemical (precipitation, oxidation), and biological (activated sludge, biological aerated filters and others) methods. This paper aims to highlight characteristics of produced water in detail and physical, chemical, and biological techniques used for its treatment. In addition, reuse of produced water for different purposes has been discussed. At the end, few case studies from different countries, related to the treatment and reuse of their produced waters have been included.

Produced water characteristics, treatment and reuse: A review

This review provides insight into the implementation of membrane technology in the petroleum industry for treating produced water that is generated from conventional oilfields in upstream and downstream processes. The ever-evolving and increasingly stringent regulatory standards for discharging produced water pose colossal environmental and economic implications because the bulk of this produced water is disposed into the environment. Thus, a review of the implementation of membrane technology for produced water treatment could contribute to the knowledge required for the increased introduction of scaled-up membrane technology in the petroleum industry. This review encompasses the capabilities and performance optimization possibilities of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes. The level of applications that these membrane technologies might attain within the petroleum industry were determined, and these implementations were correlated with the purpose, performance efficiency, treatment system configurations, necessary pretreatment procedures, quality of treated produced water, fouling occurrence and control, foulants, cleaning procedures, raw produced water content, potential challenges with corresponding applied solutions, and economic factors. This review also maps current and future trends and provides a perspective on the outlook for advances in novel membrane applications for produced water treatment.

Challenges and trends in membrane technology implementation for produced water treatment: A review

Produced water (formation and injected water containing production chemicals) represents the largest volume waste stream in oil and gas production operations on most offshore platforms. In 2003, an estimated 667 million metric tons (about 800 million m3) of produced water were discharged to the ocean from offshore facilities throughout the world. There is considerable concern about the ocean disposal of produced water, because of the potential danger of chronic ecological harm. Produced water is a complex mixture of dissolved and particulate organic and inorganic chemicals in water that ranges from essentially freshwater to concentrated saline brine. The most abundant organic chemicals in most produced waters are water-soluble low molecular weight organic acids and monocyclic aromatic hydrocarbons. Concentrations of total PAH and higher molecular weight alkyl phenols, the main toxicants in produced water, typically range from about 0.040 to about 3 mg/L. The metals most frequently present in produced water at elevated concentrations, relative to those in seawater, include barium, iron, manganese, mercury, and zinc. Upon discharge to the ocean, produced water dilutes rapidly, often by 100-fold or more within 100 m of the discharge. The chemicals of greatest environmental concern in produced water, because their concentrations may be high enough to cause bioaccumulation and toxicity, include aromatic hydrocarbons, some alkylphenols, and a few metals. Marine animals near a produced water discharge may bioaccumulate metals, phenols, and hydrocarbons from the ambient water, their food, or bottom sediments. The general consensus of the International Produced Water Conference was that any effects of produced water on individual offshore production sites are likely to be minor. However, unresolved questions regarding aspects of produced water composition and its fate and potential effects on the ecosystem remain. Multidisciplinary scientific studies are needed under an ecosystem-based management (EBM) approach to provide information on the environmental fates (dispersion, precipitation, biological and abiotic transformation) and effects of chronic, low-level exposures to the different chemicals in produced water.

Produced Water: Overview of Composition, Fates, and Effects

Hydrophobic deep eutectic solvents as "green" extraction media for polycyclic aromatic hydrocarbons in aqueous samples.

Analysis of BTEX, PAHs and metals in the oilfield produced water in the State of Sergipe, Brazil

The concentrations of Cd, Cu, Pb, Mn and Ni were determined in liver and kidney samples of adult and juvenile Puffinus gravis by Flame Atomic Absorption Spectrophotometry. The average Cd concentration in adult livers were significantly different from juveniles. Cu concentra - tion averages were significantly different between liver and kidney, as well as in between the liver of adults and juveniles. Average Mn concentrations in liver and kidney did not differ between adults and juveniles, whereas Ni concentrations in liver and kidney of adults were significantly higher than in juveniles. For Pb concentrations in liver were significantly higher in adults than in juveniles. The concentrations of essential trace elements in P. gravis were generally comparable to values reported in other studies. With non-essential metals (Cd, Pb and Ni), P. gravis had smaller values than those reported for their northern Atlantic counterparts.

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Kennedy Alexandre Souza Aragão

Papers

Analysis of BTEX, PAHs and metals in the oilfield produced water in the State of Sergipe, Brazil

Heavy metal concentration in tissues of Puffinus gravis sampled on the Brazilian coast