A review on oily wastewater: Impact, characterization, and treatment methods

The rapid expansion of industries leads to an increase in the nuisance to living beings and the environment, particularly through the rise in the discharge of toxic liquid residues. The management of oily wastewater constitutes an environmental problem due to its diverse constitution and low biodegradability, which affects ecosystems and human health. Accurate characterization of these effluents is fundamental to adapting treatment methods. Advanced techniques, such as membrane separation, adsorption, coagulation-flocculation, and advanced oxidation, as well as biological treatment, such as activated sludge processes, sequential biological reactor (SBR), and other biological systems, have been implemented to degrade oily wastewater pollution effectively; moreover, combined treatment is also considered a sustainable and efficient approach due to their large capacity to eliminate a variety of pollutants simultaneously and this technique of coupling between two processes such as flotation combined with coagulation-flocculation remains the most suitable for treating this type of effluent with very significant removal results. This study examines the different methods of controlling oily water, its environmental impacts, and the treatment techniques used. It analyses the research evaluated by experts between 2017 and 2024 on treating wastewater containing oils and fats.