The continuous rise in carbon dioxide emissions as a major driver of climate change, along with the generation of large volumes of saline effluents from desalination processes, has intensified the need for sustainable an‎d integrated solutions to mitigate both gaseous an‎d liquid pollutants. In this context, microalgae an‎d particularly Dunaliella salina have attracted significant attention due to their inherent tolerance to high salinity, adaptability to a wide range of environmental conditions, an‎d strong potential for biological carbon dioxide fixation. This study aimed to eva‎luate the performance of Dunaliella salina in carbon dioxide fixation, biomass production, an‎d improvement of reverse osmosis brine quality under different aeration rates an‎d carbon dioxide concentrations.Experiments were conducted at laboratory an‎d semi-pilot scales using reverse osmosis concentrate as the cultivation medium. Dunaliella salina was cultivated under varying carbon dioxide concentrations (0.1–1% v/v) an‎d aeration rates of 0.5 an‎d 2 vvm over a 14-day cultivation period. The results demonstrated that Dunaliella salina exhibited high growth performance an‎d effective carbon dioxide fixation even at low CO₂ concentrations. The highest biomass production (1.8 ± 0.15 g.L⁻¹) was achieved at 0.1% CO₂ an‎d an aeration rate of 0.5 vvm. The specific growth rate ranged from 0.11 to 0.21 d⁻¹, while the maximum carbon dioxide fixation rate varied between 0.07 an‎d 0.12 gCO₂.L⁻¹.d⁻¹. Analysis of the treated effluent indicated that cultivation of Dunaliella salina in reverse osmosis brine not only sustained algal growth but also led to a notable reduction in organic compounds an‎d a relative improvement in wastewater quality, thereby enhancing its potential for reuse. Elemental analysis of the final biomass revealed a favorable composition comparable to values reported in previous studies. Overall, the findings of this research suggest that cultivating Dunaliella salina under low carbon dioxide concentrations an‎d moderate aeration rates represents an efficient, cost-effective, an‎d sustainable approach for biological carbon fixation an‎d the reuse of saline effluents, with promising potential for integration into circular economy frameworks an‎d environmentally integrated systems.

محمد هادي جزيني

حميد زيلوئي , محمدامين بوجاري