Microbial Resources of Alkaline Bauxite Residue and Their Possible Exploitation in Remediation and Rehabilitation

Abstract

Bauxite residue is the by-product produced by Bayer’s process, the main industrial extraction process of aluminum. The currently estimated deposit of bauxite residue is about 3 Gigaton which is increasing every year by 120 Megaton. It is characterized by high pH, salinity along with the presence of many heavy metals and radioactive elements and is the main source of environmental pollution. Due to the absence of any prominent reuse option rehabilitation of bauxite residue disposal site is of primary concern. However, management and remediation by physico-chemical methods are neither economically viable nor environment friendly. This bauxite residue harbors functionally and genetically diverse indigenous microbial communities which have been studied by both culture-dependent and metagenomic approaches. These extremophilic microbiota has not only adapted to hostile environment but also play a critical role in the biogeochemical processes. Attempts have been initiated to assess the potential of these microbial resources for possible application in bioamelioration, bioremediation, and bioleaching of metal values from bauxite residue. Implementation of these technologies however demands success in both pilot-scale and field-level experimentations. This review will provide updated information on microbial resources of bauxite residues and their potential role in the bio-management of this unique environment.