Filtration results indicate that the ED diluate can be treated with high-recovery RO without scaling. The permeate flux was initially relatively constant during 72 h of filtration for both the constant-recovery (Figure ) and increased-recovery (Figure ) experiments, indicating no significant scaling. Ion rejection was stable, as indicated by minor changes in permeate EC (Figure ) and ion composition (Figure ), further indicating absence of mineral fouling, which may affect ion rejection by increasing concentration polarization , with constant rejection further indicating the absence of mineral fouling.