Utilizing rejected brine from desalination processes for CO2 capture: Opportunities, challenges, and sustainable integration

Desalination is a process that converts seawater to fresh water for consumption and use. The number of desalination plants has greatly increased, with current desalination capacity being at 97 Mm3/day. Despite the benefits of these plants, they suffer from high energy use, carbon dioxide (CO2) emissions, and unregulated brine disposal, which pose great ecological and environmental risks. Desalinated rejected brine consists of sodium, chloride, magnesium, and calcium, with more than 90% of rejected brine being deposited into seawater. This review discusses brine valorization to utilize the properties of brine to mineralize CO2. The recovery of minerals, such as magnesium and calcium, involves sequential precipitation, pH control, and tailored reaction kinetics, which have recovery rates of more than 95%. Numerous case studies demonstrate strong uptake of carbon while having a positive economic output. Despite these promising results, this review concludes that future directions should focus on addressing the challenges of scaling up these processes, mitigating membrane fouling and other losses, and promoting the widespread adoption of regulatory measures to limit brine discharge.