Membrane Distillation-Crystallization for inland desalination brine treatment

Abstract

Membrane distillation crystallization (MDC) is a promising technique for treatment of inland desalination brines due to its ability to recover clean water and solid salts. The MDC system developed in this study used a six-tray cascading crystallizer with extended mesh surfaces to provide nucleation sites and support for crystal growth. Sodium chloride (NaCl), potassium chloride (KCl), and sodium nitrate (NaNO3) brines were used to investigate clean water and solid salt recovery using MDC, as well as brine volume reduction. When compared to MD alone, MDC achieved higher water and solid salt recovery under the same operating conditions, resulting in greater reductions in brine volume, while retaining > 99.8% rejection for all three salt species. Solid salts were recovered from all three feed solutions, with NaNO3 feed solution, which has the strongest temperature-solubility relationship, having the highest yield (126.55 ± 6.65 g).