Biological Treatments of Oilfield Produced Water: A Comprehensive Review

Crude-oil extraction leads to the production of water, called produced water (PW). PW-flow rate increases along with the time of operation, up to more than 20 times the flow rate of crude oil. PW is often considered toxic because of its complex composition. At the moment, only dispersed hydrocarbons are targeted by water regulation. However, as regulations are becoming more stringent, they are also targeting dissolved compounds and/or the whole effluent toxicity. Consequently, PW treatments have to be more efficient, also allowing for high reliability of installations and high compactness (offshore processes). Biological treatments are often considered to offer the best compromise between removal performances and operating costs. However, their lack of compactness is unsuitable for offshore implementation. Hybrid processes, defined here as the combination of two or more processes, show promising performance and should be further studied to overcome the drawbacks noted in the case of other technologies.