Total Resource Circulation of Desalination Brine: A Review

Desalination brine is a concentrated stream that is generated during the desalination process. Brine commonly has high salinity and TDS (total dissolved ions), which contains ions such as Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, SO₄²⁻, HCO₃⁻, PO₄³⁻, and some critical elements. Currently, the brine treatment mainly applies direct disposal, like surface water discharge, sewer discharge, deep-well injection, and evaporation ponds. However, these methods can cause harm to marine ecosystems, soil, and groundwater. Therefore, brine can be regarded as a resource to be reutilized. This work then aims to highlight the novel developments of brine application. For example, Na, Ca, and Mg in brine can be employed for carbon capture and utilization with ammonia, amines, and alkaline substances. With slight adjustment, brine can also be directly used as irrigation water, aquaculture water, and the activation of biochar. Furthermore, brine holds a higher concentration of critical elements, which makes many countries and scholars start to conduct element extraction, reducing the amount of ore exploitation. At last, the major obstacles related to these advancements in sustainability, expenses, and technological aspects are outlined, and promising research trends of brine reutilization are also suggested.