Integrating Water Footprint and Life Cycle Assessment for Early-Stage Evaluation of Circular Brine Treatment Systems

Brine generated from seawater desalination presents significant environmental challenges due to its high salinity and pollutant content, particularly when discharged without adequate treatment. While advanced brine treatment systems offer opportunities for resource recovery and pollution reduction, they often involve increased energy and material demands, creating trade-offs between environmental benefits and resource consumption. This study integrates Water Footprint Assessment (WFA) and Life Cycle Assessment (LCA) to evaluate the freshwater sustainability of circular brine treatment systems under different process configurations. The framework is applied to four treatment scenarios, including variations in precipitation agents (NaOH and Ca(OH)2) and the inclusion of calcination processes, and compared with a reference scenario representing direct brine discharge. The results show that the blue water footprint is primarily driven by indirect water use associated with energy consumption, while pollutant loads influence the grey water footprint. Although advanced scenarios increase gross water demand, significant reductions are achieved through avoided water contributions from resource recovery and internal water reuse. Among the evaluated configurations, Scenario 2 exhibits the highest total water footprint due to elevated energy and pollutant-related impacts, whereas Scenarios 3 and 4 demonstrate improved performance through enhanced recovery efficiency. The water–carbon trade-off analysis highlights that minimizing carbon emissions does not necessarily reduce water consumption, emphasizing the importance of integrated assessment. Overall, the findings demonstrate that sustainable brine treatment design requires balancing water use, pollution control, energy demand, and resource recovery. The proposed WFA–LCA framework provides a robust decision-support tool for optimizing circular brine management systems.