Oilfield produced water treatment by liquid-liquid extraction: A review

Oilfield produced water treatment represent a global challenge due to the presence of several contaminants such as heavy metals and dissolved organic compounds. They cannot be removed by conventional equipment and may threat the environment when discarded. Hence, oil industry has the challenge of manage the produced water according to the disposal standards set by environmental agencies and, at the same time, overcome weight and space limitations in the platforms. Choosing the best technology involves the understanding of the process, construction and operational cost, along with the maintenance and management of the removed pollutants. In addition, different oilfield produced water composition and volume also lead to different options for its management. In this context, the study of technological routes such as liquid-liquid extraction is of great interest to the petroleum industry due to the variety of solvents and the different approaches available to accomplish the produced water treatment decontamination. Despite the extensive liquid-liquid extraction application for analysis and remediation of complex mixtures, there is no literature review on this topic. Thus, this paper presents a review of soluble organic compounds removal from oilfield produced water by the liquid-liquid extraction process. The novelty of each extraction method was highlighted and possible applications in the oil industry were identified.