Effect of operating conditions on microfiltration of an oil–water emulsion by a kaolin membrane

The main problem in treating oil in water emulsions by membrane technologies is fouling caused by oil adsorption on the membrane surface. Among these technologies, microfiltration has been used in many fields of oil–water emulsions. The effect of operating conditions on a microfilter (home made) with a maximum pore size of 10 µm was investigated. The results show that by increasing temperature and pressure, the flux factor increases. Also, by increasing oil content, the membrane is fouled rapidly but not significantly and the flux factor decreases. Increasing volumetric flow rate causes an increasing flux factor. While most polymeric membranes are susceptible to fouling, this membrane is not.

The kaolin membrane previously prepared was not significantly susceptible to fouling (as are most polymeric membranes) because of its very hydrophilic behavior. After 4.5 h it showed efficiencies higher than 50%; therefore, this membrane can be recommended for oily wastewater treatment. This membrane is very inexpensive because it can be prepared by extruding and calcining washed kaolin, which comes from Zenooz mines [6,7]. It showed good performance for oily wastewaters with concentrations of lower than 2000 ppm. It is recommended for operation at temperatures lower than 40°C because higher temperatures increased operational costs. A pressure of 2 bar is recommended for MF of oily wastewaters. Also high flow rates are suitable in order to remove the oil layer from the membrane surface.