Membrane technology is widely used as an effective water treatment or pretreatment technology, especially in the filtration of oil-in-water (O/W) emulsions. Ceramic membranes have shown excellent performance in this regard. However, due to the complex composition of real wastewater, laboratory studies are limited to the filtration of simulated O/W emulsions, and there is little research on the favorable conditions for filtering real wastewater. Additionally, since actual devices operate as constant flux units, previous studies have been conducted under constant pressure conditions, thus further understanding of the effect of membrane pore size on constant flow membrane filtration is required to better understand the situation in real plant applications.