Towards the removal of soluble organic compounds present in oilfield produced water by advanced oxidation processes: Critical review and future directions

Even with the development of alternative fuels and energy sources, the world is still highly dependent to the petroleum production and extraction. Align to this, the treatment of oilfield produced water (OPW) is a global challenge, since for each barrel of extracted oil it is produced 3 barrels of OPW in average. OPW contains numerous organic compounds, including naphthenic acids (NAs), which are considered recalcitrant compounds and are not efficiently removed by conventional OPW treatment. Advanced oxidation processes (AOPs) produce highly reactive hydroxyl radicals (•OH) and are considered a promising alternative for the degradation of resistant organic compounds. This review focuses on the treatment of OPW and degradation of pollutants present in its composition through different AOPs (ozonation, photocatalysis, photochemical oxidation and Fenton-based processes). The factors affecting the processes and strategies to improve AOPs efficiency for OPW treatment are discussed. The background information regarding each process, their main operational parameters and recent publications were addressed aiming to present viable technologies for the complete treatment of OPW. The main finds indicate that individual processes may present some limitations, and much of the emerging research in this field is directed towards the use of combined processes.