Mineral precipitation was not detected on membrane surfaces after either experiment. SEM images of the membrane surface (Figure ) revealed no distinct mineral crystals in either experiment. Elemental analysis of the membrane surface by SEM-EDS and XRD also revealed no crystals. Overall, the theoretical and empirical results thus establish the practicability of a high-recovery (up to 92%) RO step with no antiscalant addition, enabled by sulfate removal in the ED step.