Evaluation of Eutectic Freeze Crystallization (EFC) Performance of Reverse Osmosis Brine

Eutectic freeze crystallization (EFC) is a sustainable and cost-effective method for the water treatment process that can produce both water and salts.Applying EFC on a multicomponent high-concentration brine solution results in a lower freezing point and eutectic temperature where pure water as ice can be separated from pure salts that precipitate at their eutectic crystallization points.This work presents a theoretical design of a Zero-liquid discharge (ZLD) crystallizer system using EFC technology.The development of an EFC process flowsheet (OLI ESP flowsheet) based on thermodynamic modeling is illustrated for a case study of reverse osmosis (RO) retentate from an industrial plant.The model enables the prediction of eutectic temperatures, the production rate of both ice and salts and their recoveries using mass balance calculations, and the evaluation of the major energy requirements.Based on the thermodynamic modeling results, two major salt hydrates form with ice.These sequentially, the Na₂SO₄.10H₂O salt hydrate can be crystallized out at about -8 °C followed by the NaCl.2H₂O hydrate forming at -24 °C.