Ultrafiltration Separation of Crude Oil and Waste Oil

Approximately 90 million barrels of crude oil are processed daily worldwide, with separation processes such as distillation accounting for 10–15% of global energy consumption. In this regard, the scientific community is faced with the ambitious task of finding alternative fractionation technologies that are not based on the volatility of individual components of complex liquid mixtures. The driving force of ultrafiltration is the pressure difference across the membrane. Therefore, separation occurs without phase transitions and with significantly lower energy consumption compared to distillation. In recent years, there has been a growing interest in the development of membrane technologies for the purification and reuse of used lubricating oil. One of the key challenges in membrane filtration of oil and lubricants is their high viscosity. This review examines two approaches to reducing the viscosity of such systems: filtration at elevated temperatures and pre-dilution of the feedstock followed by filtration. A literature analysis revealed that in most cases, ultrafiltration with ceramic membranes is employed in the former approach, while the latter uses more cost-effective polymer membranes. Special attention in the review is given to the issues of membrane fouling and regeneration.