Membrane oscillation and oil drop rejection during produced water purification

Removal of crude oil droplets from produced water has been evaluated using a Nickel membrane with a slotted pore width of 4 gm and length of 400 mu m. The membrane was oscillated at different frequencies that resulted in variable intensity shears at the membrane surface. The influence of membrane oscillations on oil droplet rejection was investigated and reported in this work. Membrane oscillations generated a lift for the surrounding particles which led the drops to move away from the membrane surface. Measurements have shown that the intensity of the droplet lift was linearly proportional to the intensity of the applied shear. Inertial lift velocity model reported in literature was used as a starting point which was coupled with the fluid's convection velocity. The model predicted 100% cut-off points through the membrane at various oscillation frequencies. Without the applied shear rate, the static and drag forces balanced each other, which was assumed to be the 100% cut-off point. With the applied shear rate, the inertial lift and convection velocities become equal and this point was referred to as 100% cut-off point. Overall mass of crude oil droplets in permeate flow was calculated knowing the 100% cut-off point and interfacial tension between the dispersed and continuous phases. (C) 2015 Elsevier B.V. All rights reserved.