Bio-mining of Lanthanides from Red Mud by Green Microalgae

Area of Science:

• Environmental Science
• Biotechnology
• Materials Science

Background:

• Red mud, a byproduct of alumina production, contains valuable lanthanides.
• Lanthanide scarcity poses challenges for high-tech industries.
• Microalgae offer a potential biological solution for metal recovery.

Purpose of the Study:

• To investigate the potential of green microalgae for lanthanide accumulation from red mud.
• To identify the most effective microalgal species for lanthanide bio-mining.
• To evaluate the impact of red mud concentration on microalgal growth and lanthanide uptake.

Main Methods:

• Cultivation of three green microalgal species (Desmodesmus quadricauda, Chlamydomonas reinhardtii, Parachlorella kessleri) in media with varying red mud concentrations.
• Measurement of cell number doublings per day to assess growth rates.
• Quantification of intracellular lanthanide accumulation in microalgal biomass.

Main Results:

• Desmodesmus quadricauda exhibited the highest growth rate (2.71 doublings/day) and lanthanide accumulation (27.3 mg/kg/day).
• Increasing red mud concentration decreased microalgal growth due to light shadowing but increased lanthanide accumulation.
• Lanthanide content in Desmodesmus quadricauda increased significantly with red mud concentration, reaching 54.5 mg/kg at 0.1% red mud.
• Red mud supplementation alleviated metal starvation in incomplete nutrient media.

Conclusions:

• Green microalgae, particularly Desmodesmus quadricauda, are effective in accumulating lanthanides from red mud.
• This study demonstrates the potential of microalgae for bio-mining or bio-leaching of lanthanides from industrial byproducts.
• Further research can optimize conditions for large-scale lanthanide recovery using algal biotechnology.