Separation of Oil and Grease From Wastewater: A Multidisciplinary Review of Treatment Technologies

ABSTRACT Oil and grease (O&G) wastewater generated from different sources possesses a varying complex chemical nature, physical states, and persistent in aquatic systems, resulting in significant environmental and operational challenges. This multidisciplinary review critically examines conventional, advanced, and emerging technologies for the separation and treatment of O&G‐laden wastewater. It explores the environmental implications and health risks associated with O&G‐contamination, including aquatic toxicosis, bioaccumulation, and infrastructure degradation. Uses of traditional approaches are acceptable due to their simplicity and cost‐effectiveness; but for emulsified and dissolved fractions require an integration of advanced techniques. Membrane filtration (UF, NF, RO), electrocoagulation, adsorption using novel materials, advanced oxidation processes (AOPs), and magnetic separation offer enhanced removal performance and adaptability. Applications of biological methods like microbial degradation, enzymatic treatment, constructed wetlands, etc., represent eco‐friendly alternatives. This review emphasizes hybrid and integrated systems such as membrane bioreactors (MBRs), physico‐biological combinations, and electrochemical‐adsorptive setups, which leverage synergistic mechanisms to improve removal efficiency and operational robustness. Here, some key designs are considered, such as pH, temperature, O&G concentration, sludge management, energy demands, etc. It emphasizes the potentiality of O&G recovery and reuse, notably in biodiesel production and energy recovery. Surfactants and natural organic matter mainly stabilized oil and water emulsion, reduce droplet coalescence, and intensify membrane fouling and coagulant demand, and difficult to operate. Elevated salinity and divalent cations modify interfacial charge, and alter electrocoagulation efficiency, adsorption equilibria, and microbial activity. High suspended solids and colloidal loads further exacerbate pore blocking, sludge production, and hydraulic instability, thereby limiting flux, increasing energy consumption, and complicating scale‐up. Despite significant progress, it faces some challenges. Future research may establish predictive design models and standardized performance benchmarks. Present review is strongly connected to current research gaps and future directions towards low carbon & energy and resource‐recovery‐oriented treatment systems to address monitoring of O&G pollution in wastewater.