A Study of the Effect of Red Mud Amendments on the Growth of Cyanobacterial Species

Abstract

ABSTRACT Red mud is a bauxite residue, a by-product of the Bayer process for extraction of alumina from bauxite ore. It is highly alkaline in nature and contains heavy metal oxides and a variety of minor trace elements. Its disposal is the paramount environmental issue in alumina refining. Establishment of vegetation on red mud dumping sites is difficult because of alkaline pH and high concentrations of soluble ions and toxic compounds. The bioremediation of red mud seems to be a realistically convenient way for environmentally safe disposal of this industrial residue. The present study specifically deals with the utilization of cyanobacteria to bioremediate red mud. Being predominantly a nitrogen-fixing photosynthetic microorganism, it has considerable potential for bioremediation of bauxite residue. As a prelude step, four cyanobacterial species, viz. Oscillatoria sp., Lyngbya sp., Phormidium sp., and Microcystis sp. were selected to study their capability to grow on red mud–amended medium. The results indicate that Oscillatoria and Phormidium performed well on red mud–amended medium, followed by Lyngbya. Growth of Microcystis was inhibited significantly even at lower concentrations of red mud amendments. These findings point out the potential of these microorganisms, to be utilized as active biological agents for bioremediation of red mud.