Prediction of supersaturation and monitoring of scaling in reverse osmosis and nanofiltration membrane systems

Long-term performance and fouling analysis of full-scale direct nanofiltration (NF) installations treating anoxic groundwater

“…The NPD increased by 10% and the K w decreased by 5.1%. After 2 years the recovery was optimized with the use of a ScaleGuard s [20]. The ScaleGuard s tests indicated that the recovery could be increased to 83%.…”

“…The normalizations described are generally used by the Dutch drinking water companies. The normalized specific water permeability of the membranes (K w ) represents the actual membrane flux corrected for surface area, the net driving pressure (subtraction of osmotic pressure differences between feed and permeate from transmembrane pressure) and temperature (reference temperature 10 1C) [20].…”

“…The risk of inorganic precipitation can be calculated based on the saturation index of minerals from the feed water [20]. For the described installations, this was calculated with Troi, a software program supplied by Trisep.…”

Removal of fluoride and uranium by nanofiltration and reverse osmosis: A review

“…Despite the contribution of diffusion, the increase in water flux surpasses the increase in convective transport of the solute, and therefore the retention increases. However, as the pressure increases, concentration polarization in the boundary layer increases and hence solute diffusion increases (Van de Lisdonk et al, 2001). Concentration polarization leads to increased osmotic pressure and thus decreased flux.…”

Overview of Membrane-Assisted Crystallization Operations

“…2,6 Accordingly, initial interest in crystallization and membranes was principally motivated by the necessity to adopt strategies to avoid solid formation and precipitation on the membrane surface. 7 A further application of a membrane unit as a crystallizer dates back to 1986, when RO hollow fibers were used to simulate the early stages of stone formation in the renal tubules due to precipitation of calcium oxalate. [8][9][10] In 1989, the possibility to crystallize a solute by using MD at sufficiently high concentration was roughly envisaged.…”