Biomining using microalgae to recover rare earth elements (REEs) from bauxite.

[Display omitted] • The optimal pulp ratio ranges from 0.2 % to 0.6 %. • Pigments and Ca-Mg ATPase enzyme increased up to 10 % in the culture with bauxite. • Chlorella vulgaris was the most promising one than other microalgae species. • The optimal aeration rate ranged from 0.4 vvm to 1.2 vvm. • HRT 4d recovered REEs two times higher than HRT 3d. Biomining using microalgae has emerged as a sustainable option to extract rare earth elements (REEs). This study aims to (i) explore the capability of REEs recovery from bauxite by microalgae, (ii) assess the change of biochemical function affected by bauxite, and (iii) investigate the effects of operating conditions (i.e., aeration rate, pH, hydraulic retention time) to REEs recovery. The results showed that increasing bauxite in microalgae culture increases REEs recovery in biomass and production of biochemical compounds (e.g., pigments and Ca-Mg ATPase enzyme) up to 10 %. The optimum pulp ratio of bauxite in the microalgae culture ranges from 0.2 % to 0.6 %. Chlorella vulgaris was the most promising, with two times higher in REEs recovery in biomass than the other species. REEs accumulated in microalgae biomass decreased with increasing pH in the culture. This study establishes a platform to make the scaling up of REEs biomining by microalgae plausible. [ABSTRACT FROM AUTHOR]