Restoration of fly ash dump through biological interventions

Abstract

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.

Revegetation of Fly Ash ‒ A Review With Emphasis on Grass-Legume Plantation and Bioaccumulation of Metals

“…Despite of the fact, that these microbes are gradually brought into the site from neighboring soils, predominantly in the form of air-borne inoculums, FA makes it a tough medium for their survival and colonization . Notwithstanding all this, different species of mycorrhiza as well as Rhizobium have been found to possess varying range of survival potentials on FA medium (Juwarkar and Jambhulkar, 2008). The tolerant fungi and bacteria get the advantage of being selected during progressive vegetation establishment, forming symbiotic associations with existing and invading plant species leading to beneficial outputs.…”

“…Furthermore, there exists specificity in symbiotic association of legumes and strains of Rhizobium and accordingly leguminous seeds or plants are often inoculated with appropriate Rhizobium strain. In some studies, rhizobial and mycorrhizal inoculums had been isolated from an already revegetated site in view of their tolerance to the FA medium (Juwarkar and Jambhulkar, 2008). Some non leguminous trees have also been found to be symbiotically associated with N 2 -fixing organisms (e.g.…”

Fly Ash Pollutants, Treatment and Recycling

“…2005). The toxicity of heavy metals from FA, such as Pb, Ni, Cr, Zn, Cu, and Cd, were reduced with the increase of organic matter content in the FA dump by building complexes with the heavy metals (Juwarkar and Jambhulkar 2008). Other beneficial effects for combining FA with organic matter on soil are e.g.…”

Dual Inoculation of Arbuscular Mycorrhizal and Phosphate Solubilizing Fungi Contributes in Sustainable Maintenance of Plant Health in Fly Ash Ponds

“…In this study, pH of the fly ash decreased in all treatments from slight alkaline to moderate acidic range. The pH reduction in fly ash may be due to presence of high content of sulfur in fly ash while leaching of base ions (Juwarkar and Jambhulkar 2008). Since C and N in the fly ash are likely to be oxidized to gaseous constituents during combustion, they usually are present in trace amounts and P in fly ash is relatively unavailable to plants (Bradshaw and Chadwick 1980).…”