Sulfate ion removal from reverse osmosis concentrate using electrodialysis and nano-filtration in combination with ettringite precipitation

Abstract

NF membranes reject divalent ions ($$ {{\text{SO}}_{4}}^{2 - } $$ ) at much higher rate than monovalent ions (Cl−); Electrodialysis showed higher removal efficiency of $$ {{\text{SO}}_{4}}^{2 - } $$ and Cl−; Sulfate coexists with calcium- and aluminum-enhanced ettringite precipitation. © Springer Nature Switzerland AG 2020.