Microfiltration of deforming oil droplets on a slotted pore membrane and sustainable flux rates

► A 4 μm slotted pore membrane used for separation of 1–15 μm oil droplets from water using oscillatory microfiltration. ► Shear rates of various intensities (6–21 Hz) were applied to minimise membrane blocking. ► A simple blocking model adequately described the membrane blocking that either shear or deforming droplets led to sustainable flux. ► The blocking model helped that membrane/particle interaction coefficient varied in a logical manner with respect to shear. Oil droplets from an emulsion were filtered using a slotted pore membrane with a 4 μm slot width and 400 μm slot length. Droplets up to 15 μm in diameter were filtered at various flux rates (200–1200 l m −2 h −1) using oscillatory membrane microfiltration. Surface shear rates at the membrane of various intensities (0, 1200, 3200 and 8100 s −1) were applied and the effect on permeate flux rate and trans-membrane pressure were investigated. Near constant filtration flux was obtained for all the tests. Without shear the trans-membrane pressure increased quickly, but at the highest shear rate (8100 s −1) nearly constant trans-membrane pressure and flux rate were observed and may be described as sustainable, or weak form of critical flux. A filtration membrane blocking model was used to investigate the filtration and identify when sustainable, or critical, flux was achieved.