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.

Assessment of bioaccumulation of heavy metals by different plant species grown on fly ash dump.

A field experiment was conducted on a 10-hectare area on fly ash dump at Khaperkheda Thermal Power Plant, Nagpur, India, where different ecologically and economically important plant species were planted using bioremediation technology. The technology involves the use of organic amendment and selection of suitable plant species along with site-specific nitrogen-fixing strains of biofertilizers. The study was conducted to find out the metal accumulation potential of different plant species. The total heavy metal contents in fly ash were determined and their relative abundance was found in the order of Fe>Mn>Zn>Cu>Ni>Cr>Pb>Cd. Fly ash samples had acidic pH, low electrical conductivity, low level of organic carbon and trace amounts of N and P. Plantation of divergent species was done on fly ash dump using the bioremediation technique. After 3 years of plantation, luxuriant growth of these species was found covering almost the entire fly ash dump. The results of the metal analysis of these species indicated that iron accumulated to the greatest extent in vegetation followed by Mn, Ni, Zn, Cu, Cr and Pb. Cassia siamea was found to accumulate all metals at higher concentrations compared to other species. The experimental study revealed that C. siamea could be used as a hyper-accumulator plant for bioremediation of fly ash dump.

Phytoremediation of coal mine spoil dump through integrated biotechnological approach.

Field experiment was conducted on mine spoil dump on an area of 10 ha, to restore the fertility and productivity of the coal mine spoil dump using integrated biotechnological approach. The approach involves use of effluent treatment plant sludge (ETP sludge), as an organic amendment, biofertilizers and mycorrihzal fungi along with suitable plant species. The results of the study indicated that amendment with effluent treatment plant sludge (ETP sludge), @ 50 ton/ha improved the physico-chemical properties of coal mine spoil. Due to biofertilizer inoculation different microbial groups such as Rhizobium, Azotobacter and VAM spores, which were practically absent in mine spoil improved greatly. Inoculation of biofertilizer and application of ETP sludge helped in reducing the toxicity of heavy metals such as chromium, zinc, copper, iron, manganese lead, nickel and cadmium, which were significantly reduced to 41%, 43%, 37%, 37%, 34%, 39%, 37% and 40%, respectively, due to the increased organic matter content in the ETP sludge and its alkaline pH (8.10-8.28), at which the metals gets immobilized and translocation of metals is arrested. Thus, amendment and biofertilizer application provided better supportive material for anchorage and growth of the plant on coal mine spoil dump.

Fly ash toxicity, emerging issues and possible implications for its exploitation in agriculture; Indian scenario: A review.

Fly ash is considered as an environmental hazard worldwide, since it generally contain organic pollutants, probable toxic metals like Se, As, B, V, Al, Pb, Hg, Cr and radionuclide's Uranium, Thorium. Although fly ash contains toxic substances, it also contains most of the oxides and trace elements. Presence of oxides contributes to its alkaline pH while trace elements provides nutrients for plant growth hence, it is suggested that it can be used in low concentration in agriculture sector as well as a soil conditioner as fly ash improves the physico-chemical and biological properties of contaminated soils. This article presents a review on causes of fly ash toxicities due to organic pollutants, heavy metals, radioactive elements and environmental issues related to its utilization and possibilities of fly ash exploitation in agriculture sector such as phytoremediation, bioremediation, reclamation of wasteland and forestry.

Restoration of fly ash dump through biological interventions.

Field experiment on 10 ha area of fly ash dump was conducted to restore and revegetate it using biological interventions, which involves use of organic amendment, selection of suitable plant species along with specialized nitrogen fixing strains of biofertilizer. The results of the study indicated that amendment with farm yard manure at 50 t/ha improved the physical properties of fly ash such as maximum water holding capacity from 40.0 to 62.42% while porosity improved from 56.78 to 58.45%. The nitrogen content was increased by 4.5 times due to addition of nitrogen fixing strains of Bradyrhizobium and Azotobacter species, while phosphate content was increased by 10.0 times due to addition of VAM, which helps in phosphate immobilization. Due to biofertilizer inoculation different microbial groups such as Rhizobium, Azotobacter and VAM spores, which were practically absent in fly ash improved to 7.1 x 10(7), 9.2 x 10(7) CFU/g and 35 VAM spores/10 g of fly ash, respectively. Inoculation of biofertilizer and application of FYM helped in reducing the toxicity of heavy metals such as cadmium, copper, nickel and lead which were reduced by 25, 46, 48 and 47%, respectively, due to the increased organic matter content in the fly ash which complexes the heavy metals thereby decreasing the toxicity of metals. Amendment of fly ash with FYM and biofertilizer helped in profuse root development showing 15 times higher growth in Dendrocalamus strictus plant as compared to the control. Thus amendment and biofertilizer application provided better supportive material for anchorage and growth of the plant.