Simultaneous brine and CO2 utilization in construction material production: A life cycle assessment

Abstract. Economic development has led to a significant increase in CO2 emissions, resource depletion, and freshwater demand. In arid regions, seawater desalination has been employed as a reliable source of freshwater. However, the environmental challenges associated with reject brine management have been increasingly scrutinized for their adverse effects on adjacent ecosystems. Recent research efforts have explored the potential for simultaneous treatment of CO2 emissions and reject brine, by recovering valuable minerals and converting waste into a resource. This study presents a life cycle assessment (LCA) of construction material produced using industrial byproducts locally sourced in the Gulf region. The production process involves two main stages: CO2 absorption from flue gas in an alkaline solution and subsequent ex-situ mineralization. Desalination reject brine is used as a steady source of dissolved Ca²⁺ and Mg²⁺, contributing to a circular. The developed construction product exhibits superior mechanical performance compared to industrial standards. The presented LCA examines environmental impacts, including climate change, resource depletion, and water use. The new material contains approximately 30 wt.% sequestered CO₂. The total quantified environmental impacts include 0.391 kg CO₂ eq. for climate change, 0.23 kg oil eq. for fossil depletion, and 0.021 m³ for freshwater consumption per kilogram of plasterboard. These findings underscore the potential of this innovative process to provide sustainable construction alternatives while mitigating the impacts of CO₂ emissions and waste from desalination.