Effects of Colloidal Fouling and Concentration Polarization on RO Membrane Performance

Concentration of rejected salt at the membrane surface when colloidal particles were deposited on the membrane was determined experimentally based on measured salt permeate. This approach allowed for a clear identification of individual contributions of concentration polarization and colloidal fouling to the permeate flux decline. The observed transient behavior of permeate flux, salt rejection, mass of deposited colloids and effective porosity of the deposited layer pointed to the influence of the coupled membrane fouling on membrane performance and formation process. The result showed that the high solution ionic strength would reduce porosity of the deposit and increase its resistance, which strongly effect on the permeate flux. On the other hand, deposition of colloidal particles on the membrane surface caused the RO membrane rejection performance deteriorating and the trend became strong with colloidal concentration increase.