Enhancement of Heavy Metals Retention in Sandy Soil by Amendment with Fly Ash

Improving heavy metals retention by amending soil with fly ash was investigated. Batch sorption experiments with Cu, Pb, and Zn were conducted on three soils, fly ash, and Dougherty sand with 2.5% and 5% by weight fly ash. Column leaching experiments were performed to obtain the break-through curves (BTCs), and the column cores were sectioned to determine the spatial distribution of any non-eluted heavy metals. Dougherty sand improved its heavy metals retention greatly, and in the case for Zn, the distribution coefficient was increased by a factor of 40 when 5% fly ash was added. This increase was due to the elevated pH and content of Al, Fe, and Ca oxides. Column leaching experiments with transport modeling of the results showed that adding fly ash to Dougherty sand increased its heavy metals retardation dramatically.