Fractionation and transport of nutrients among coal ash residues and in soil covered with fly ash-amended organic compost

Abstract

Coal-fired power plants generate different types of ash residues and discharge small particles and vapors to the atmosphere. The ash residues which account for the major part of the byproducts are collected and stored as bottom ash, boiler ash, and fly ash, weathered ash and ash in lagoon. Analysis of water extracts of these residues will reveal how the nutrients are distributed in these residues and transported to aquatic systems. Equally interesting is the study of the downward movement of nutrients in soil treated with fly ash-amended organic compost when used as a manure for agricultural crops. In this work water extracts of different types of ash residues and eluates from descending ports of an experimental column of soil at different depths were also analyzed. Our results showed that there is considerable difference in the efficiency of removal and deposition of nutrients on different residues collected from the power plant and stored outside. Bottom ash was found to accumulate K, N, and S while Ca is enriched in ash from lagoon. Transition metals such as Zn, Mn, and Cu are concentrated in weathered ash. The concentration of most of the nutrients was found to decrease, in column experiments, as a function of depth and level to a depth of 80 cm.