Removal and recovery of Critical Rare Elements from contaminated waters by living Gracilaria gracilis

The experiments performed in this work proved the ability of Gracilaria gracilis to concentrate and recover Critical Rare Elements (CRE) from contaminated waters. The importance of recycling these elements is related to their very limited sources in Nature and progressive use in technologies. Moreover, their mining exploitation has negative environmental impact, and recent studies point them as new emerging pollutants. To the best of our knowledge, this is the first report on the application of living macroalgae for the removal and recovery of CRE. G. gracilis (2.5 gL(-1) fresh weight) was exposed to mono- and multi-element saline solutions of 500 mu g L-1 of Y, Ce, Nd, Eu and La. Removal was up to 70% in 48 h, with bioaccumuladon following Elovich kinetic model. In multi-element solutions, selectivity was not observed although removal of lanthanides improved comparatively to single-element solutions. No mortality or adverse effect on growth was registered. The subsequent macroalgae digestion allowed collecting virtually 100% of all elements in a 300-fold more concentrated solution. The overall results suggest the application of living macroalgae as a simple and effective alternative technology for removing and recovering CRE from wastewaters, contributing to an improvement of water quality and CRE recycling. (C) 2017 Elsevier B.V. All rights reserved.