Bio-regeneration of different rich CO₂ absorption solvent via microalgae cultivation

As one of the most mature carbon capture technologies, thermal regeneration of rich CO₂ absorption solvent is a crucial challenge due to its high energy consumption (typically in the range of 3-6 MJ/kg CO₂). In this work, a concept of bio-regeneration was proposed using microalgae to convert bicarbonate (which is one of the dominant components in rich solution) into value-added biomass. To evaluate the performance of bio-regeneration, different rich solution (including NH₄HCO₃, KHCO₃ and NaHCO₃) were investigated. Experimental results indicated that NH₄HCO₃ could be a promising bicarbonate carrier for the proposed absorption-microalgae hybrid process, which had a higher biomass productivity (55.36 mg·L^-1·d^-1) compared to KHCO₃ and NaHCO₃ and carbon sequestration capacity could be up to 158.3 mg·L^-1·d^-1. Meanwhile, pH adjustment was an effective approach to further intensify the performance of hybrid process. As a result, bio-regeneration of solvents could be a promising alternative to the conventional thermal regeneration.