The　discharge　of　rare　earth　element　(REE)　tailings　wastewater　results　in　serious　ecological　deterioration　and　health　risk,　due　to　high　ammonia　nitrogen,　and　strong　acidity.　The　low　C/N　ratio　makes　it　recalcitrant　to　biodegradation.　Recently　it　has　been　shown　that　microalgal　technology　has　a　promising　potential　for　the　simultaneous　harsh　wastewater　treatment　and　resource　recovery.　However,　the　low　nitrogen　removal　rate　and　less　biomass　of　microalgae　restricted　its　development.　In　this　work,　Chlorococcum　sp.　was　successfully　isolated　from　the　rare　earth　mine　effluent.　The　microalgae　was　capable　of　enhancing　nitrogen　contaminants　removal　from　REEs　wastewater　due　to　the　carbonate　addition,　which　simulated　the　activity　increase　of　carbonic　anhydrase　(CA).　The　total　inorganic　nitrogen　(TIN)　removal　rate　reached　4.45　mg/L　h(-1),　which　compared　to　other　microalgal　species,　the　nitrogen　removal　rate　and　biomass　yield　were　7.8-and　4.9-fold　higher,　respectively.　Notably,　high　lipid　contents　(mainly　triglycerides,　43.85%　of　dry　weight)　and　a　high　biomass　yield　were　obtained.　Meanwhile,　the　microalgae　had　an　excellent　settleability　attributed　to　higher　extracellular　polymeric　substance　(EPS)　formation,　leading　to　easier　resource　harvest.　These　results　were　further　confirmed　in　a　continuous-flow　photobioreactor　with　a　stable　operation　for　more　than　30　days,　indicating　its　potential　for　application.