Leaching Study of Trace Elements from Ash Ponds of Coal based Thermal Power Plants and its Impact on Quality of Surface and Ground Water in the Flood Plain Area of River Yamuna Delhi

Abstract

In the present study, laboratory leaching tests have been conducted using extraction apparatus fabricated in the laboratory to determine the potential mobility of trace elements like Fe, Cu, Cr, Pb, Ni and Cd from fly ash samples. Batch leaching experiments have been carried out to determine the leaching characteristics of trace elements from coal fly ash obtained from Rajghat Power Station, Indraprastha Power Station and Badarpur Thermal Power Station located in Delhi. The shake tests were performed as per the American Society of Testing Materials (ASTM) method using a agitation device designed to rotate about a central axis at the rate of 100 rpm with an L/S ratio of 20:1, using 12.50 gm dried fly ash in 250ml of extraction solutions over varying periods of leaching. The leachates obtained analyzed for selected trace elements. The results for leachates indicate that there is no regular pattern of leaching of trace elements. Among the trace metal originally present in fly ash, Pb and Cd occur, at very minor concentrations in the leachates obtained over the different intervals. The other elements such as Fe, Ni, Cu and Cr which were detectable in the leachates show their presence. The agitation time influenced the pH and the concentration of different elements leached into the solution, since different phases are dissolved at different rate. newline newlineThe objectives of this study were achieved through an experimental phase. The experimental phase consisted of a series of laboratory batch tests on fly ash samples collected from Rajghat Power House, Indraprastha Power Station and Badarpur Thermal Power Station located in Delhi using number of controlled test conditions.