The Continuous Induced Air Flotation of Highly Stabilized Oil in Water Emulsions

Abstract

Abstract The performance of a 12 L induced air flotation (IAF) cell has been evaluated for the continuous separation of highly stabilized oil in water (o/w) emulsions. Emulsions created for test purposes had stability rate constants (Ks) less than 0.06 h-1 and narrow droplet size distributions with mean diameters less than 20 um. Removal efficiences were expressed in terms of both total organic carbon (TOC) and oil removed. In addition, a solvent extraction/spectrophometric analysis enabled residual surfactant concentrations in the cell effluent to be determined. The main variables that affected the flotation cell operation were the following: air superficial velocity (O.5-4.O cm/s), liquid residence time (3-15 min), de-emulsifier concentration (0-160 mg solution/L), and gas distributor design. Under the best continuous operating conditions, the flotation cell removed oil droplets above 2.0 um giving oil removal rates greater than 95 percent. On the other hand, improper control of the independent variables resulted in poor cell performance with separations as low as 20 percent.