Thermodynamic modeling of eutectic freezing for enhanced seawater desalination and reverse osmosis brine treatment

The escalating discharge of hypersaline brine streams necessitates sustainable wastewater treatment solutions. Eutectic freeze crystallization (EFC) emerges as a promising approach, offering a near zero liquid discharge (ZLD) solution with reduced energy consumption. This work explores thermodynamic modeling of EFC for seawater desalination and reverse osmosis (RO) brine treatment. Through a comprehensive analysis of brine composition and thermodynamic modeling, the behavior of salt and ice formation during the freezing process is investigated. Brine composition analysis reveals the prevalence of chloride, sodium, sulfate and magnesium in all streams. Thermodynamic modeling predicts the crystallization behavior of different salt hydrates, including their eutectic temperatures and yields. Notable formation of Na2SO4 & sdot;10H2O and NaCl & sdot;2H2O is reported. Accordingly, various scenarios to achieve a near ZLD were proposed, with a highest ice recovery of 93 % obtained for seawater compared to the diluted RO brine (91 %) and the undiluted RO brine (88.8 %), respectively. The energy consumption during the EFC process of undiluted RO brine stream is evaluated, indicating a total energy consumption of 54 kWh/m3. This work offers deeper understanding of salt crystallization behavior in complex multicomponent brine streams and aims to demonstrate the potential of EFC in achieving near ZLD as a sustainable brine management solution for the desalination industry.