A Study on the Efficient Separation of Oily Water Using Mullite Whiskers Membrane through Combined Filtration and Electrofiltration

Oily wastewaters pose significant environmental challenges, requiring effective treatment methods for sustainable development. This study investigates the potential of combining filtration, electrofiltration, and backwashing using a ceramic membrane for the treatment of oily water. A secondary mullite membrane is synthesized, demonstrating favorable characteristics such as high permeate flux (534 LMH), biaxial flexural strength (75.21 MPa), and cost-effectiveness. Experimental investigations were performed for operational parameters, resulting in the selection of a pressure of 2 bar and a cross-flow velocity of 0.727 m/s to achieve desirable permeate flux and oil removal rates. The critical electric field intensity (Ecrit) is determined experimentally and theoretically, ranging from 50 to 55 V, guiding the selection of optimal voltages for electrofiltration. Electrokinetic phenomena, including electrophoresis, electroosmosis, and bubble formation, are harnessed to mitigate fouling. The influence of feed solution conductivity is examined, revealing that higher salt concentrations increase fouling and diminish electric field effectiveness. Energy consumption analysis indicates significant potential for energy savings, with a decrease from 3.88 kWh/m³ in the no-voltage condition to 2.71 kWh/m³ at 65 V for salt-free solutions. However, at higher salt concentrations, increased fouling and reduced electric field effectiveness result in higher energy consumption. The findings underscore the suitability of low-cost ceramic membranes for oily water treatment, emphasizing the importance of optimizing operating parameters for enhanced performance and energy efficiency.