Immobilization of Fusarium verticillioides fungus on nano-silica (NSi-Fus): A novel and efficient biosorbent for water treatment and solid phase extraction of Mg(II) and Ca(II)

► Novel biosorbents were used for water treatment of Mg(II) and Ca(II). ► A combined nano-SiO2 and Fusarium verticillioides fungus (Fus). ► The metal sorption processes were optimized. ► Sorption equlibria were described by various models. ► Successful applications for real sea water softening and treatment.