PHYTOREMEDIATION OF METAL MINE WASTE

Phytoremediation is a group of technologies that use plants to reduce, degrade, or immobilize environmental toxins, primarily those of anthropogenic origin, with the aim to clean-up contaminated areas. In this review paper, different types of phytoremediation processes, typical plants used and their application for clean-up of metal contaminated sites were reviewed. Plant responses to heavy metals and mechanisms of metal uptake and transport were also discussed. Phytoremediation of Pb, Zn, Cu and Fe tailings and mine spoils were carried out by grasses, herbs and shrubs, which could be categorised as As accumulator (Paspalum, Eriochloa, Holcus, Pennisetum Juncus, Scirpus and Thymus), Pb accumulator (Brassica juncea, Vetiveria, Sesbania, Minuartia, Juncus, Scirpus and Thymus), Cu accumulator (Ammania baccifera, Scleranthus) Zn and Cd accumulator (Vetiveria, Sesbania, Viola, Sedum, Rumex). The research work showed that, bioavailability and metal uptake by plants could be accomplished by ameliorating pH, addition of organic amendment, fertiliser and chelating agents. Further research is required to develop fast growing high biomass plants with improved metal uptake ability, increased translocation and tolerance of metals through genetic engineering for effective phytoremediation of metal mine wastes.