Selective recovery of magnesium and calcium from RO brine reject

Title : Selective recovery of magnesium and calcium from RO brine reject

Abstract:

The sustainable management of high salinity brine resulting from seawater desalination has been and remains one of the most pressing environmental issues. It proposes a sequential integrated precipitation process for total valorisation of real Reverse Osmosis (RO) brine using basic solution and carbon dioxide (CO₂), whereby magnesium (Mg⁺²) and calcium (Ca⁺²) will be selectively recovered as industrial minerals with very high added value. The process exploits solubility differences that the target ions manifest as a function of pH to accomplish stepwise fractionation. First, Mg⁺² was quantitatively recovered (>95 %) as brucite, Mg(OH)₂, with >95 % purity at pH>10, thereby eliminating essentially all scaling potential from the brine. Subsequently, Ca⁺² was selectively precipitated as thermodynamically stable calcite (CaCO₃) via controlled carbonation at pH >8.5, with >95.0% recovery efficiency and virtually no contamination by Mg⁺². The recovered phases were verified by mineralogical characterization to be of distinctly crystalline morphology and high elemental purity by XRD, XRF, and SEM studies, therefore lowering the environmental brine disposal burden while targeting a practical approach towards the circular economy desalination cycle.

Keywords: Crystallization; SWRO brine valorization; Mg(OH)₂; Calcite; Desalination

Biography:

Qazi Iqra Shafi, is a PhD candidate at KFUPM, Saudi Arabia. She is working as a research student in the field of Membrane science and water treatment technologies. Her research focuses on desalination setups using crystallization. She have achieved a milestone in her research area and am currently excelling in the fundamentals of the second part of her research. On the other hand, she is serving as a lab instructor in her department.