Improvement in microfiltration process of oily wastewater: A comprehensive review over two decades

Microfiltration (MF) technology has become an emerging and promising separation process for oily wastewater (OW) pre-treatment owing to its high oil separation efficiency and ease of operation. Membrane fouling by oil droplets is the most critical problem in utilizing the MF process, which finding new procedures to eliminate or at least postpone its formation is an important issue at present. In the current review, various perspectives are presented to introduce comprehensive development in the MF process over the past twenty years. First, the researches on the simple MF process are compared for commercial and modified ceramic and polymer-based membranes. Second, hybrid technologies containing the MF process are surveyed to examine their effects on water content and quality. Third, the applied enhancement methods on the MF process like turbulence promoter and external forces, including electric field, ultrasonic field, and UV irradiation, are summarized. Finally, future outlooks are briefly discussed for further advancement in the MF process of OW treatment for eventual implementation in industrial scales, especially by incorporating nanoparticles with excellent photocatalytic and hydrophilic characteristics in MF membranes.