Sustainable Brine Management and Carbon Dioxide Capture: Minimizing Water Footprint, Addressing Environmental Challenges, and Promoting Resource Recovery

Desalination plants play a crucial role in meeting the growing demand for potable water. While they are highly efficient in producing desalinated water, they also generate a significant amount of reject brine, a highly concentrated saline waste stream. Disposing of this brine poses a major challenge for the desalination industry, as traditional methods often involve discharging it into the sea, resulting in environmental damage and marine pollution. Furthermore, this discharge amplifies the water footprint of desalination operations, exacerbating the overall environmental impact. The discharge brine can affect nearby water sources, like rivers, lakes, or underground aquifers. It makes the water in those sources less usable for things like drinking, agriculture, or supporting aquatic life. Additionally, the reliance on desalination in some countries contributes to greenhouse gas emissions due to the energy-intensive nature of the process. 

This chapter aims to address these challenges and explore sustainable solutions for brine management in desalination. The increasing capacity of the desalination industry, driven by population growth and the depletion of other water resources, calls for urgent action. The primary concern lies in the emissions of pollutants, particularly brine, which has significant adverse effects on marine life. Furthermore, the continuous disposal of brine elevates seawater salinity, increasing energy requirements for desalination processes. Additionally, the energy-intensive nature of desalination plants, often located near power stations, results in large quantities of carbon dioxide (CO₂) emissions. 

In this chapter, we focus on highlighting brine management techniques, specifically electrodialysis using carbon dioxide. This approach enables the simultaneous removal of liquid and gaseous pollutants, while also offering the potential for creating value-added products such as carbonate/bicarbonate salts and inorganic acids. Additionally, we discuss the importance of pretreatment using selective electrodialysis to prevent scaling issues caused by the reaction of divalent ions with carbonate/bicarbonate ions. 

By exploring these innovative brine management techniques, this chapter provides insights into sustainable practices that can help mitigate the environmental impact of desalination. Furthermore, it emphasizes the need for a holistic approach that addresses both liquid and gaseous pollutants, ensuring the long-term viability of desalination as a water supply solution.