Eco-restoration approach for mine spoil overburden dump through biotechnological route

The overburden dumps which are created during the process of mining are devoid of supportive and nutritive capacity for biomass development. Restoration of these overburden dumps requires the establishment of a self-sustaining soil–plant system, for which a restoration strategy is needed to accelerate the natural processes of ecosystem development. For eco-restoration of a coal mine spoil dump, National Environmental Engineering Research Institute developed an ecofriendly multidisciplinary approach to restore the fertility of the mine spoil overburden dump. In this regard, an experiment was conducted to restore the fertility of the overburden dump in an area of 20 ha at Durgapur in India. To reclaim the dump, the IBA (integrated biotechnological approach) was used. The integrated biotechnological approach involves the utilization of industrial waste ETP sludge (effluent treatment plant sludge) to support the nutritive capacity for vegetation establishment, inoculation, and isolation of Azotobacter, Bradyrhizobium, and VAM (vesicular arbuscular mycorrhiza) spores of Gigaspora and Glomus species along with suitable indigenous trees of ecological and economic importance. The findings of the experimental study revealed that amendment of the mine spoil with organic amendment at 50 t/ha improved the nutrient, microbiological, and physicochemical properties of the coal mine spoil and reduced the toxicity of heavy metals due to increased organic carbon content of the organic amendment effluent treatment plant sludge. Thus, amendment of the effluent treatment plant sludge and biofertilizer application provided better supportive material for the growth of different plant species which resulted into momentous biomass (aboveground biomass and belowground biomass) production thereby improving the productivity and fertility of the mine spoil dump in a short span. Thus, using IBA, the ecology and biodiversity of the area was conserved. It also helped to maintain the aesthetic environment surrounding the mine site.