Comparative study of elemental transport and distribution in soils amended with fly ash and sewage sludge ash

摘要

Disposal of various coal combustion and municipal by-products is a serious and challenging problem due to strict environmental regulations. This is due to the threat of accumulation of certain heavy metals in soils, plants and groundwater when these products are used as soil amendments or disposed of in landfills. This chapter describes a study that was undertaken on a coarse and medium textured soils amended with single rate of (74.1 Mg ha 1) fly ash (FA), sewage sludge (SS) and sewage sludge ash (SSA) to compare the transport and leaching potential of various elements and their distribution within 30-cm soil columns. Transport and leaching potential of macro nutrient elements were highest in SSA amended soils followed by SS and FA. Leaching potential of Cr, Cd and Ni were the lowest in SSA followed by SS and FA. In addition, the total quantity of metals in the leachate (total of 2640 mL) were generally greater when the amendments were applied to coarse textured soil compared to medium textured soil with the exception of Pb. The results also suggest that binding sites created by the interaction between soil and amendments may modify metal adsorption-desorption and solubility, with a consequential effect on leaching and downward transport of various elements.