A novel analytical approach for the estimation of shear in the oscillatory membrane microfiltration

Abstract

A novel analytical approach for estimating the shear rate over the membrane surface and away from the membrane surface as a result of the membrane oscillation has been presented. The model was developed and modified according to our system using the Stokes boundary layer equation. Generation of the shear over the membrane surface is an important phenomenon that not only mitigates the fouling but also enhances the separation efficiency. It is investigated that membrane oscillating frequency, amplitude and viscosity of the souring fluid are important parameters that influence the intensity of the shear on the membrane surface and away from the surface. The model presented was tested with various set of frequencies, amplitudes and viscosities. While, keeping the amplitude constant and changing the frequencies, ahigherintensity of shear over the membrane surface was noticed. On the other hand, keeping the frequency constant and changing the amplitude, a lower shear on the membrane surface was observed. Similarly, as expected, a lower shear over the membrane surface was noticed when the viscosity of the surrounding fluid was increased. The model was supported with the experimental results where separation of oil drops from produced water was the focus of the experiments conducted. It was clear from the experimental results that membrane oscillation enhanced the separation efficiency of the membrane used and therefore, concentration of oil drops in the permeate decreased. Further, the application of the shear was greatly influenced by the pore blocking; higher the shear rate; lower was the pore blocking and vice versa.