Heavy metals leaching in Indian fly ash.
Bably Prasad1, Kajal Kumar Mondal
1Central Institute of Mining and Fuel Research, Barwa Road, Dhanbad-826 001, Jharkhand. drbablyprasad@yahoo.com
Journal of Environmental Science & Engineering
|March 20, 2009
Summary
Fly ash, a waste from thermal power plants, poses environmental risks. Laboratory leaching tests reveal varying metal mobility, with zinc and iron leaching most from Chandrapura and Ramagundam samples, respectively.
Area of Science:
- Environmental Science
- Geochemistry
- Waste Management
Background:
- Fly ash is a major industrial byproduct of thermal power plants, posing significant environmental risks due to improper disposal.
- While some fly ash utilization exists in construction and agriculture, a large proportion remains a disposal challenge.
Purpose of the Study:
- To assess the potential mobility and leachability of heavy metals (Pb, Cd, Cr, Cu, Zn, Fe, Mn, Ni) in fly ash from two Indian thermal power plants.
- To understand the environmental risks associated with fly ash disposal based on laboratory leaching tests.
Main Methods:
- Laboratory leaching tests, specifically a cascade-leaching test, were conducted on fly ash samples from Chandrapura and Ramagundam Thermal Power Plants.
- Liquid-to-solid ratios (L/S) between 20 and 100 were employed, and pH was monitored, showing neutral reactions for both samples.
Main Results:
- The study identified distinct leaching trends for metals: Zn>Fe>Mn>Cr>Pb>Cu>Ni>Cd for Chandrapura fly ash and Fe>Zn>Cu>Mn>Cr>Ni>Pb>Cd for Ramagundam fly ash.
- Metal release from the ash surface was inversely correlated with pH, decreasing as pH increased.
Conclusions:
- Fly ash composition influences metal leachability, with significant mobility observed for certain metals like zinc and iron.
- Understanding metal mobility through leaching tests is crucial for assessing the environmental impact and managing the disposal of fly ash waste.
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