Synergistic Effect of Ca²⁺ and SO₄^2- Ions and Gypsum Scaling in Feed Solution on Forward Osmosis Boron Removal

Abstract

This paper investigates the synergistic effect of Ca2+ and SO42- ions in feed solution on the forward osmosis (FO) removal of boron by a thin-film, composite membrane with embedded supports of polyester screens (TFC-ES). Specifically, water flux, reverse solute flux, boron flux and boron rejection rate were examined respectively to explore the influence of gypsum scaling on boron removal. The results indicate that gypsum scaling in the FO suppresses water flux and boron flux. After the surface of the polluted TFC-ES membrane was cleaned by deionized water, the membrane performance was recovered efficiently, as evidenced by the water flux recovery rate of 95.05%, and the boron rejection recovery rate of 94.21%. This research demonstrated the potential of the FO membrane in boron removal.