Silica scale inhibition and colloidal silica dispersion for reverse osmosis systems

Problems associated with water containing high levels of dissolved and/or colloidal silica have been observed in many reverse osmosis (RO) systems. This study examines a new silica inhibitor that inhibits silica scale formation and disperses colloidal silica in RO systems. Mechanisms of the silica scale inhibition and colloidal silica dispersion are proposed. Pilot studies were conducted to determine silica scale inhibition and colloidal silica dispersion in various RO systems and water compositions. The silica inhibitor was used in pilot studies with concentrate water silica levels up to 370 ppm. Analysis of the normalized permeate flow, salt passage data, membrane autopsies and foulant analyses from the pilot systems show the silica inhibitor to be effective at inhibiting silica scale. Guidelines for its use are presented. Implications for the RO industry are discussed.