Liming Characteristics of a High-Calcium, Dry Flue Gas Desulfurization By-product and its Effects on Runoff Water Quality

In 2013, only 37% of the 32 million Mg of flue gas desulfurization (FGD) by-products generated in the United States were reused beneficially. If FGD by-products could be used as a beneficial soil amendment, millions of megagrams may be diverted away from surface impoundments and landfills. The purpose of this research was to identify the liming characteristics of a high-Ca dry FGD (DFGD) by-product in comparison to a Class-C fly ash (FA) and reagent-grade CaCO3, and to evaluate the effects of land application to a managed grassland on runoff, plant, and soil quality. Liming characteristics were determined by measuring the calcium carbonate equivalence (CCE), degree of fineness (DOF) and calculating the effective neutralizing value (ENV). The DFGD by-product was land-applied to a managed grassland in May 2015 and runoff, plant, and soil samples were collected over a 12-mo period. The ENV of 79.4% for the DFGD by-product was lower (P < 0.05) than that of reagent-grade CaCO3, but similar to the ENV of commercially available liming materials. The DFGD by-product was as effective as reagent-grade CaCO3 at raising soil pH when incubated at a rate equivalent to the soil’s lime requirement and more effective than reagent-grade CaCO3 when incubated at 2x the soil’s lime requirement. Seasonal flow-weighted mean Ni concentrations and seasonal V loads were 44.5 and 86.9%, respectively, greater (P < 0.05) when amended compared to the unamended control during at least one season. One month after application, aboveground dry matter and tissue As, Se, Cr, Co, Hg, V, and U concentrations were between 53 and 471% greater in the amended treatment than in the unamended control. Trace element concentrations decreased to pre-application levels within six months. Results demonstrated that the high-Ca DFGD by-product used in this study is a viable liming material and has minimal effects on runoff and plant quality when applied at a rate of 9 Mg ha. Consequently, land application of high-Ca DFGD by-products may be a viable alternative to current disposal methods. Acknowledgements I would like to thank the members of my Advisory/Thesis Committee, Dr. David M. Miller, Dr. Kristofor R. Brye, Dr. Lisa S. Wood, and Erik D. Pollock for guiding me in my research and the preparation of this thesis. I would like to thank Dr. David M. Miller for inspiring my passion for soil science, and for providing insightful guidance throughout my academic career. Without Dr. Miller’s passion for soil science and his ability to teach, I would never have pursued soil science as a field of study. I am forever grateful for the inspiration and guidance received from Dr. Miller during my time at the University of Arkansas. I would like to thank Dr. Kristofor R. Brye for his guidance throughout my graduate career. Dr. Brye’s attention to detail and dedication to research and the editing process was instrumental to my success and the preparation of manuscripts and this thesis. I would like to thank Dr. Lisa S. Wood for acting as a mentor throughout my undergraduate and graduate career at the University of Arkansas. The advice received throughout my academic career from Dr. Wood has shaped the direction of my academic and professional