Abstract
Reject brine discharge and high CO2 emissions from desalination plants are major contributors to environmental pollution. Managing reject brine involves significant costs, mainly due to the energy-intensive processes required for brine dilution and disposal. In this context, Solvay process represents a mitigation scheme that can effectively reduce reject brine salinity and sequestering CO2 while producing sodium bicarbonates simultaneously. The Solvay process represents a combined approach that can effectively manage reject brine and CO2 in a single reaction while producing an economically feasible product. Therefore, this study reports a systematic techno-economics assessment of conventional and modified Solvay processes, while incorporating brine and carbon tax. The model evaluates the significance of implementing a brine and CO2 tax on the economics of conventional and Ca(OH)2 modified Solvay compared to industries expenditures on brine dilution and treatment before discharge to the sea. The results show that the conventional Solvay process becomes profitable after applying a brine tax of 1 dollar per meter cube of brine and a CO2 tax of 42 dollars per tonne CO2 —both figures lower than the current costs associated with brine treatment and existing carbon taxes. Moreover, the profitability of the Ca(OH)2-modified Solvay process increases even further with minimal brine and CO2 taxes. The findings highlight the significance of adopting modified Solvay process as an integrated solution for sustainable brine management and carbon capture.