Trace Element Sampling and Partitioning Modeling to Estimate Wastewater Composition and Treatment Efficacy at Coal Generators

Coal-fired power plants (CFPPs) have and will continue to adapt to tightening environmental regulations and changing environmental conditions by implementing additional air pollution control systems and wastewater treatment technologies. Proposed work develops a Trace Element Emissions Model (TEEM) to predict coal contaminant partitioning in conventional air pollution control devices (APCDs) and water pollution control devices (WPCDs) to understand the fate of trace elements in CFPPs. The first objective is to quantify trace elements in the coal combusted at U.S. CFPPs by integrating USGS county-level coal sampling data with plant-level reporting of coal purchases to US EIA with the goal of understanding: Significant variability in trace element concentration within coal ranks, Spatially-resolved approaches that will allow for a more accurate inventory of the amounts of trace element entering power plants. The second objective is to develop a model to predict trace element partitioning in air pollution control devices (APCDs) for a variety of trace elements of environmental significance and importance to the FGD wastewater treatment train (e.g. Hg, Se, As, Cl, Pb, Br, B, NO3-/NO2-) using a combination of literature studies and observations collected at three plants in collaboration with Louisville Gas & Electric and Kentucky Utilites (LGE-KU), with the assumptions that: Trace elements have different boiling/condensation temperatures and so they condense out of the gas stream at different points in the flue gas treatment train, Modeling trace elements partitioning in APCDs is critical to understanding the ultimate environmental fate of trace elements. The third objective is to develop predictive models for trace element removal in FGD wastewater treatment systems that are likely to be adopted for compliance with the Effluent Limitation Guidelines (ELGs): chemical precipitation, biological treatment, and mechanical vapor compression using data collected by the EPA and with LGE-KU with the goal of: Understanding how trace elements are partitioned to solid and liquid phases during FGD wastewater treatment and so contribute to the ultimate fate of trace elements, Informing power plant decision making around ELG compliance by developing a set of typical FGD wastewater stream compositions and speciation, removal in treatment processes, and cost models.