Selective precipitation of calcium ion from seawater desalination reverse osmosis brine

The near zero liquid discharge (NZLD) approach, by recovering water and dissolved valuable salts, is the most attractive clean solution for valorisation of brines from seawater desalination reverse osmosis (SWD-RO) plants. In this perspective, a key aspect calcium removal/recovery, to avoid scaling problems in successive advanced separation units other salts. work sodium citrate (Na 3 C 6 H 5 O 7 ), carbonate 2 CO ) hydrogencarbonate (NaHCO were tested as precipitation reagents. Different pH, temperature, ionic strength reagent molar ratio maximize Ca 2+ minimize Mg loss. Aqueous solutions containing ions with/without all major electrolytes used. chemical basis processes discussed based on effective ion surface density (e.g. Slater rule), hydration Eigen association process precipitate formation complex multicomponent brine. PhreeqC Medusa equilibrium numerical codes applied some experimental data providing good agreement between calculated values. removal efficiency higher than 90% coupled with an loss below 7% was obtained at 60 °C controlled using NaHCO . These results are very promising view designing valorisation, thus mitigating environmental related SWD-RO disposal. • more efficient Nacitrate Na gave selective Ca(II) compared Mg(II) PhreeqC- llnl able model >90% aragonite <7% Recovery salts RO mitigates their disposal