Simultaneous CO₂ and biogas slurry treatment using a newly isolated microalga with high CO₂ tolerance

The fixation of carbon dioxide (CO₂) using microalgae is a promising CO₂ capture and utilization technology. Microalgae have also been suggested as a potential treatment for biogas slurry (BS). This study screened microalgae capable of tolerating both high CO₂ concentrations and BS, assessed their CO₂ fixation and pollutant removal capabilities, and evaluated the potential use of the resulting algal biomass. Chlamydopodium sp. HS01, which showed the highest tolerance to 15% CO₂ and BS, was selected due to its strong growth, CO₂ fixation, and ammonia nitrogen removal abilities. The generated biomass also demonstrated significant potential for bioenergy production. Metabolomics analysis revealed that the lipid composition of HS01 underwent substantial changes under 15% CO₂ alone and in combination with BS, likely as a stress adaptation strategy. Overall, HS01 presents high potential for resource utilization of CO₂ coupled with actual BS.