Novel wastewater recovery process for sustainable sodium carbonate production with CO2and SOxutilization

Ammonia-soda process, which produce soda ash, emits flue gas containing a large amount of CO2and SOx. The wastewater discharged from the ammonia-soda process contains cations, such as Na+and Ca2+, which can be recovered and reacted with a CO2and SOx. In this study, we designed a CO2and SOxutilization process for the sustainable production of sodium carbonate using wastewater recovery system, extracting Na+and Ca2+. The proposed process involved the following steps: (1) metal-ion separation, which produces NaOH and Ca(OH)2; (2) capture and utilization of SOxusing Ca(OH)2; and (3) capture and utilization of CO2using NaOH and Ca(OH)2, respectively. The economic feasibility of the proposed process was verified by comparing its total annualized cost (TAC) with those of conventional processes. Approximately 99% of SOxwas captured to produce high-purity desulfurized gypsum, and 99% of CO2was captured to be transformed into CaCO3. To confirm the CO2reduction of the process, the carbon dioxide equivalent (CO2e) was calculated by evaluating the amount of greenhouse gases. The CO2e decreased to 71.4% compared with that of the conventional process. The TAC of the proposed process decreased by 10.67% and 19.63% compared with that of the ammonia-soda and Hou processes, respectively. Thus, this study proposes an industrially potential process design for sustainable sodium carbonate production by utilizing CO2and SOxwith wastewater recycling, without additional reactants, making it more economically viable.