The problem of disposal of brine due to increased MD/RO desalination plant has recently become a big social issue. The chlor-alkali process through electrolysis of brine has been studied as a method to overcome this problem. In order to increase the electrolysis efficiency, a pretreatment process for removal of hard substances must be preceded. In this study, we investigated the mechanism of removal of hardness through chemical precipitation. As a result, Ca was greatly influenced by addition of Na2CO3, and Mg was strongly influenced by pH. Also, the addition of NaOH and Na2CO3 enabled simultaneous removal of Ca and Mg, and showed a removal efficiency of 99.9% or more. Finally, the residual concentrations of Ca and Mg in the brine after the reaction were 0.14 and 0.13 mg/L, respectively. Saturation index was calculated using Visual MINTEQ 3.1, and solid phase analysis of the precipitate was performed by FE-SEM and PXRD analysis. It was confirmed that precipitate formed by the formation of calcite and brucite.

• 심재호(한양대학교 건설환경공학과) | Jae-Ho Shim (Department of Civil and Environmental Engineering, Hanyang University)
• 박재철(한양대학교 건설환경공학과) | Jae-Chul Park (Department of Civil and Environmental Engineering, Hanyang University)
• 임대환(한양대학교 건설환경공학과) | Dae-Hwan Lim (Department of Civil and Environmental Engineering, Hanyang University)
• 박주양(한양대학교 건설환경공학과) | Joo-Yang Park (Department of Civil and Environmental Engineering, Hanyang University) Corresponding author