Comparative evaluation of Chlorella vulgaris and Salvinia natans for the treatment of Mining Wastewaters

The treatment of mining wastewaters and recovery of critical elements are serious component of a sustainable water management and resource recovery. However, the efficiency of wastewater treatment strongly depends on the physicochemical characteristics of the effluent, particularly its elemental composition and pH. A laboratory-scale bioremediation method using living Chlorella vulgaris and Salvinia natans species as secondary treatment step for mining wastewater was studied. The removal performance of Chlorella vulgaris and Salvinia natans was tested separately using synthetic multielement solutions containing regulated and unregulated elements at an initial concentration of 500 µg/L. Both biological systems showed high removal efficiency especially for Al, V, Cr, Ag, Pb, and U, as well as for rare earth elements such as Y, La, Ce, Pr, Nd, Sm, Eu, and Gd. The obtained results indicated element-specific uptake behavior and highlighted the potential of both microalgal and macrophyte-based systems for the simultaneous removal of toxic and critical elements from complex aqueous matrices. The environmental stress induced by multielement exposure was further evaluated through total protein quantification and the analysis, providing insight into the physiological response and tolerance of the studied species during the treatment process. The obtained results recommend the applicability of Chlorella vulgaris and Salvinia natans as nature-based bioremediation systems, sustainable and low-cost alternatives for the treatment of mining wastewaters and recovery of valuable elements.

Acknowledgement: This work is supported by the European Union's Horizon Europe Research and Innovation Program through the REESOURCE Project under Grant Agreement number 101138460