Leaching study of trace elements from coal ashes: A case study of Bokaro Thermal Power Station "B"

Electricity generation has been increasing at a rapid rate due to rapid industrialization and changing life styles. In our Country coal is the major source of energy since India has vast reserves of thermal power grade coal. Nearly every naturally occurring element is likely to be present in coal and these get entertained in the resultant coal ash. Indian coals contain high ash coupled with low calorific value and consequently resulting huge amount of coal ashes. This ash accumulates in on site piles and ponds thereby resulting in serious environmental problems particularly trace elements contamination of ground and surface waters. This study envisages the environmental assessment of coal ashes from Bokaro Thermal Power Station- Leaching study of coal ashes was made through analysis of leachates from open percolation leaching column experiments over a period of 300 days. Trace elements were observed within the regulatory limits. Many of the trace elements evaluated viz. Ni., Co, Se, Al, As, B, Ba, Sb, Hg, were observed at below detection limits of AAS. Na, K, Ca, Fe, Pb, Cd and other dissolved ions leached at significant concentration levels. This study suggests low cost high volume utilisation of bottom ash as fill material for reclaiming surrounding abandoned mined out areas in an environmentally acceptable manner.