Experimental verification of a model for rotating reverse osmosis

Reverse osmosis (RO) is an efficient process for the removal of ionic and organic pollutants from contaminated water. In this study, rotating RO, which takes advantage of Taylor-Couette flow instabilities to reduce the flux decline related to concentration polarization and membrane fouling, was investigated experimentally and compared to a dynamic model based on RO membrane transport incorporating concentration polarization. The model matches the experiments quite well. Increasing the rotational speed and transmembrane pressure enhances the flux and rejection in rotating RO.

The following conclusions can be drawn from this work: 1. The measured flux and rejection from the experiments match the model results quite well. 2. Flux is greater for a higher concentrate flow because the axial flow washes solute out of the device. However, this also results in a lower recovery of permeate. 3. Flux and rejection increase with higher transmembrane pressure. 4. Increasing the rotational speed enhances flux and rejection probably due to enhanced shear and Taylor vortices in the annulus that reduce concentration polarization near the mem-brane and mix the fluid throughout the annulus.