Chapter 10 Biological recovery of rare earth elements from mine drainage using the sulfidogenic process Elis W. Nogueira, Roseanne B. Holanda, Gunther Brucha and Márcia H. R. Z. Damianovic 10.1 INTRODUCTION The rare earth elements (REE) include 15 elements of the lanthanide family, scandium (Sc) and yttrium (Y). They are generally classified as light-REE (La, Ce, Pr and Nd), middle-REE (Sm, Eu, Gd, Tb and Dy) and heavy-REE (Ho, Er, Tm, Yb, Lu and Y) (Cao et al., 2019; Lefticariu et al., 2020). Despite what the name suggests, rare earth elements are not rare or earth. They are found in the earth’s crust in abundance. However, the term ‘rare’ is more related to the difficulty in exploiting the deposits, because of the low concentrations of the elements which often make the area economically non-viable for exploration (Edahbi et al., 2018a). These elements have gained importance due to their excellent catalytic, optical, electronic and magnetic properties, in addition to having high economic value. REE are mainly used in the electronic, catalyst, ceramic and glass, metallurgical, polishing and other industries. In hi-tech industries, these elements are applied for the production of hybrid and electric vehicles, automotive sensors, permanent magnets used in wind turbines, fuel cells, rechargeable batteries, cell phones, fluorescent lamps, computers, catalytic converters, driver discs, plates and screens (Lefticariu et al., 2020; Salo et al., 2020). They are also used in medicinal © 2022 The Editor. This is an Open Access book chapter distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for noncommercial purposes with no derivatives, provided the original work is properly cited (https://creativecommons. org/licenses/by-nc-nd/4.0/). This does not affect the rights licensed or assigned from any third party in this book. The chapter is from the book Environmental Technologies to Treat Rare Earth Elements Pollution: Principles and Engineering by Arindam Sinharoy and Piet N. L. Lens (Eds.). doi: 10.2166/9781789062236_0227 Downloaded from http://iwaponline.com/ebooks/book/chapter-pdf/980571/9781789062236_0227.pdf by guest on 24 December 2021