AWWA MTC57610

Membrane fouling due to scale formation of inorganic salts is a serious problem limiting the application of Reverse Osmosis (RO) technology. In this study, a rotating RO system taking advantage of Taylor-Couette flow instabilities was investigated to control CaSO4 scale formation. Permeate flux and the particle concentration in bulk phase were measured under various conditions to determine the degree to which rotation of the RO membrane improves flux. In rotating RO, flux decline due to scale formation is much slower than in non-rotating RO. This is because the precipitate formation in rotating RO is mostly bulk crystallization, rather than surface scale formation. Vortices in rotating RO induce bulk crystal formation and minimize scale particle deposition on the membrane surface, thereby enhancing the permeate flux. Vortices also lower the concentration polarization that is related to surface crystal formation. The anti-fouling effect in rotating RO increases with the rotational speed because of increased shear and vortices. Includes 28 references, figures.