A Critical Review of Advanced and Emerging Technologies for the Treatment of Industrial Oily Wastewater

Industrial oily wastewater, produced by petroleum refineries, petrochemical plants, automotive manufacturing, metal processing, and food industries, poses significant environmental and public health challenges due to its complex composition, which includes free, dispersed, emulsified, and dissolved oil fractions, as well as suspended solids and dissolved organics. Conventional treatment methods, such as gravity separation, skimming, coagulation–flocculation, and biological processes, are often limited in effectively removing stable emulsions and recalcitrant organic pollutants. This review critically evaluates the efficiency, advantages, limitations, and operational considerations of advanced and emerging treatment technologies, including membrane filtration, advanced oxidation processes, electrochemical methods, nanomaterial-based approaches, and hybrid systems. Comparative analyses of conventional, advanced, and hybrid systems are presented to inform technology selection for different industrial applications. The review also identifies key research gaps, highlighting the need for pilot-scale studies, cost optimization, and sustainable design strategies. Overall, this study provides a comprehensive overview to guide the development of effective, scalable, and environmentally sustainable solutions for industrial oily wastewater management