Green approach of chemical immobilization of lead inmetal-contaminated soils of NCT of Delhi using rock phosphate and coal fly ash

Author(s): Mamta Chhabra Sharma, Reena Saxena, Sandeep K.Sharma, Suniti Singh

Contaminated sites are the legacy of a long period of industrialization involving unconsidered production and handling of hazardous substances and unregulated dumping of wastes. Metal contamination need to be characterized on varying temporal and spatial scales. Keeping this object in mind, soil used for this study was collected from a Pb contaminated site in an industrial area ofNaraina andMayapuri in theNCT ofDelhi. EPAMethod 3051 is commonly regarded as a regulatory alternative toMethod 3050. It is a rapid and accurate dissolution technique for soil metal ions. This technique is time saving and energy efficient. No acid fumes are generated. For all these reasons the above technique can be considered a green technique. Remedial measures required to clean up metal contaminated sites are often complex and economically unsustainable. Immobilization of the metal ions e.g., Pb, Zn and Cd by green amendments like rock phosphate and coal fly ash is promising and economically feasible technique. In this connection a bench scale investigation has been carried out to access the potential use of these amendments for immobilizing these metal ions in severely contaminated sites in Delhi. Parallel experiments have been carried out in columns with unamended and amended soil samples. Results have indicated that metal content in percolating waters are drastically diminished when amendments are admixed with soils.

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