Plant based removal and recovery of rare earth elements

Abstract

The impact of urbanization and industrialization has accelerated the degradation of environmental components. Industrial wastewater and ore mining act as a hotspot for entry of metals, metalloids and rare earth elements (REE) to freshwater ecosystems. They are found in the form of cations, inorganic or organic complexes of humic and fulvic acid as a part of the dissolved organic matter (DOC) and also bound to the suspended solids. This necessitates the use of technologies that assist in the removal of these heavy metals, metalloids and REE. Active (such as precipitation or ion exchange) (Babel & Kurniawan, 2003) or passive (wetlands or by granulate substances) (Kropfelova et al., 2009) water filtration systems have been used successfully. Considering wetland ecosystems, which act as a sink for metals, metalloids or REE, both natural and constructed wetlands (CWs) can be employed for the above purpose. CWs mimic natural wetlands and are considered as innovative technology that can treat a wide range of pollutants, including nutrients, organic pollutants, bacteria, antibiotic resistant genes, heavy metals, metalloids and REE (Stefanakis, 2019). Wetlands have the potential to remove pollutants by complex reactions involving the plants, microbes and substrates/media along with the process of sedimentation (Davranche et al., 2016). The main benefits of nature based solutions to be employed on fields are the low construction and operational cost and low maintenance requirement. Moreover, the energy requirement is almost negligible which shows their suitability in both rural