Scaling of RO membranes from silica supersaturated solutions

The paper describes results of experiments performed with supersaturated silica feed solutions, aiming to elucidate basic silica scaling phenomena with and without the presence of antiscalants. The experimental program covered a wide range of silica feed concentrations. Most experiments were performed at relatively low silica supersaturation levels in the range of practical applications (supersaturation ratio, s/s, up to about 2). Silica scaling under such conditions was characterized by a deposition mechanism of monomeric silica. The experiments carried out at high silica supersaturation levels (around s/s = 4) displayed a strikingly different mechanism involving colloidal particles deposition followed by some monomeric deposition. Concomitantly, permeate flux decline was also significantly different at low and high silica supersaturation levels, respectively.