CHEMICAL AND ADSORPTION BEHAVIOR OF WEATHERED COAL COMBUSTION PRODUCTS

Previous studies have shown that coal combustion residuals (CCRs) can impair water quality, especially by increasing the concentration of contaminants such as As, Se, B, Sr, and SO₄ in effluent. In December 2008, an ash pond dike broke at the TVA Kingston Fossil Plant in Kingston, TN and released 1.1 billion US gallons of coal fly ash slurry into the nearby Emory and Clinch Rivers. The rivers provide drinking water for three counties, sustain local fish and wildlife, and support recreational areas. This study evaluated samples from eleven different locations in the Emory and Clinch River channels, including locations upstream and downstream. Each sample was leached with deionized water at a liquid to solid ratio of 10:1, and duplicated to leach for one hour, one day, one week, thirty days, and sixty days. The sediment and ash/sediment mixture samples were imaged using a scanning electron microscope (SEM) with backscattered electron imaging to understand morphology and surface adsorption before and after leaching, while mineralogy before and after leaching was determined with XRD methods. Concentrations of contaminants released from the sediment and ash were measured using IC and ICPMS methods. The concentrations measured of constituents released are compared to concentrations measured in the river and interstitial pore water from literature. This study reveals that despite leaching the released ash continues to pose a threat to the water quality of the Emory and Clinch Rivers in certain environments.