Performance evaluation of a pilot-scale membrane filtration system for oily wastewater treatment: CFD modeling and scale-up design

The discharge of oily wastewater into the environment adversely impacts the ecosystem and human health due to the existence of toxic and carcinogenic compounds in oil. To decrease the destructive environmental impacts, membrane filtration technology has been used because it can remove emulsified oil with droplet sizes ranging from 1 to 10 mu m which is a challenging issue for other types of treatment methods. In this research, a comprehensive 3D CFD model was developed to investigate the oily wastewater treatment process in a pilot-scale membrane filtration system. The model was validated using available data in experimental runs such as oil removal efficiency and average transmembrane pressure (TMP) for two types of oily wastewater containing heavy and light crude oils. Following that, the hydrodynamic condition of the pilot-scale unit was analyzed which is difficult to be investigated in a real condition. The impacts of inlet oil concentration, permeate, and aeration flow rates on permeate oil concentration and TMP were also evaluated. Results revealed when the inlet oil concentration was at the threshold of 270 and 330 mg/L containing heavy and light crude oil, respectively, the system met the International Convention for the Prevention of Pollution from Ships (MARPOL) 73/78 regulation. Additionally, the model was capable of predicting TMP changes under constant flux. Finally, the validated model was used to upscale the pilot-scale system to achieve a permeate production rate of 10,000 L/h for larger capacities. Based on the results, the oil removal efficiency was above 88 % in pilot and upscaled systems.