Assessing the solubility of inorganic compounds from size-segregated coal fly ash aerosol impactor samples

An important issue for the coal-fired utility industry is the release of heavy metals contained in fly ash. Before companies can plan emission minimization strategies for these compounds, they must have an accurate means of predicting the forms of occurrence in the waste stream and the solubility of these forms into the surrounding environment. The EPAʹs Toxicity Characterization Leaching Protocol (TCLP) Method 1310 was modified to allow the testing of inorganic compounds contained on greased impactor membranes. The modified method was used to explore the solubility of four trace elements from five different types of coal fly ash. For most coals, selenium has limited solubility at pH 5.0 and is not expected to significantly impact groundwater sources. Arsenic, antimony, and cobalt are typically partially soluble at pH 5.0 and a portion of these metals may migrate out of the ash particles. Further, these metals show increased solubility at pH 2.9.