This work evaluated the performance of real rare earth elements (REEs) wastewater purification and carbon dioxide (CO2) fixation by Chlamydomonas sp. YC with pilot-scale airlift-photobioreactors (AL-PBRs), tubular photobioreactors (TB-PBRs) and raceway ponds (ORWPs) under high-temperature outdoor conditions in summer. The obtained results showed that Chlamydomonas sp. YC at 1 g/L oyster shell piece (OSP) and 3 % CO2 had the highest biomass (1.9 g/L) and NH4+-N removal efficiency (34.0 %) during the REEs wastewater treatment. Among the selected photobioreactors, Chlamydomonas sp. YC to treat real REEs wastewater at 3 % CO2 under high-temperature outdoor conditions attained the highest biomass (2.3 g/L) in the TB-PBRs with the best NH4+-N removal efficiency (43.0 %). Furthermore, the input cost and CO2 net sequestration evaluation revealed that TB-PBRs was more economical photobioreactors to treat REEs wastewater and fix CO2 by Chlamydomonas sp. YC, providing some vital scientific details for REEs wastewater and CO2 fixation by microalgal biotechnology.