Evaluating the Effects of Biochar and Biosolid Amendments on the Mobility and Toxicity of Metals in Fly Ash Contaminated Soils.

As the world’s energy needs have increased, so has the dependence on fossil fuel consumption. Though there has been a push towards renewable energy in the United States, there is still a great reliance on fossil fuels where coal is used as a primary energy source. The byproducts of coal consumption were historically dumped in unlined and unmanaged ponds leaving contaminants such as arsenic, mercury, and lead vulnerable to leaching into the groundwater. And though these byproducts are now more carefully regulated, many retired coal disposal ponds have residual contamination that remains untreated. Prior research has demonstrated that biochar can be used as a treatment method to inhibit mobilization of trace elements at contaminated sites and mining sites; however, the effect of biosolids, wastewater treatment byproducts, have not been examined for their effectiveness in remediating coal byproduct contaminants. In this study, we explore the use of biochar in combination with biosolids to effectively reduce contaminant mobility and subsequent toxicity of fly ash contaminated land. To do this, we quantified the amount of trace element leaching attenuated from fly ash contaminated sandy loam soil similar to that of a coal ash disposal site in Oregon containing amendments of either biochar, biosolids, or both using aqueous phases and solid phases analyses (e.g., ICP-MS, XRD, SEM, and chemical extractions). The results of this study demonstrate the first use of biosolids to remediate fly-ash disposal land and can be used to optimize current methods used to remediate coal ash contaminated land.