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Evaluating the constituent leaching from flue gas desulfurization gypsum (FGDG) under different leaching conditions, its geochemical interactions with main soil constituents and identifying potential beneficial applications

Koralegedara, Nadeesha H
http://orcid.org/0000-0002-3269-0355
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470757622

Abstract Details

2016, PhD, University of Cincinnati, Engineering and Applied Science: Environmental Engineering.
The feasibility of the use of flue gas desulfurization gypsum (FGDG) in beneficial applications was evaluated in this study. Release of toxic elements, which is the main environmental concern of the use of FGDG was evaluated under different environmental conditions. Modern and traditional EPA leaching protocols were used to evaluate the release of constituent of concern (COCs) at different pH and liquid-solid ratios. The leaching of COCs from FGDG and FGDG amended soil was tested using the aforementioned leaching protocols. The leaching of COCs was negligible from the FGDG and FGDG-amended soil, signifying its land application would not be an environmental concern. Natural gypsum (MG) is being used for agricultural purposes as a fertilizer and a structural amendment. As both MG and FGDG are chemically and physically similar, the MG is being replaced by FGDG in many applications. Despite the main similarities in chemistry, there could be some differences between the natural and synthetic gypsums in their mineralogy, trace element content and chemical speciation. The present study compared the chemistry, mineralogy and chemical association of elements in MG and FGDG. The effect of the two types of gypsums on soil chemistry when they used as soil amendments was also evaluated. Two batch leaching protocols were used to measure the release of COCs at different pH and LS ratios. The data revealed no significant difference in element leaching from the two types of gypsums and amended soils. The likelihood of FGDG to remove Pb in aqueous phase was studied using Pb spiked water. The effect of sorbent loading, sorbate concentration and system pH on Pb removal by FGDG was evaluated. The solid residues at each pH were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The presence of SO42-, CO32- and OH- in FGDG enables the formation of different Pb precipitates such as anglesite, larnakite (pH 2), leadhillite, cerussite (pH 5.5-8), hydrocerussite (pH 11). The release of COCs from FGDG at the aforementioned conditions was negligible designating its potential use in treating Pb contaminated water. The feasibility of FGDG to reduce Pb leaching in contaminated soil was evaluated using two different Pb contaminated soils. The soils were amended with 5% FGDG, and subjected to four different leaching conditions. The alterations in Pb speciation in FGDG amended soils after each leaching tests was analyzed by X-ray absorption spectrometry (XAS). FGDG effectively reduced the Pb leaching from smelter Pb contaminated soil under all the studied conditions, mainly by forming anglesite and leadhillite. Further, it was confirmed the formation of Fe-Pb-SO4 ternary complexes on ferrihydrite by FTIR analysis. These ternary complexes reduce the leaching of Pb sorbed to ferrihydrite. However, the FGDG amendment did not effectively reduced Pb leaching in organic matter rich soil under toxicity characteristic leaching conditions. The increased leaching of Pb, bound to humic acid in the presence of FGDG is suggested as the most likely reason for this. Therefore, the FGDG is recommended to stabilize ferrihydrite rich contaminated soil but not organic matter rich soil.
Dionysios Dionysiou, Ph.D. (Committee Chair)
Souhail R. Al-Abed, Ph.D. (Committee Member)
Sivaraman Balachandran, Ph.D. (Committee Member)
Margaret Kupferle, Ph.D. P.E. (Committee Member)
179 p.
Environmental Engineering
Flue gas desulfurization gypsum; Metal leaching; Lead stabilization; EPA-leaching Methods; Anglesite; Leadhillite

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Citations

  • Koralegedara, N. H. (2016). Evaluating the constituent leaching from flue gas desulfurization gypsum (FGDG) under different leaching conditions, its geochemical interactions with main soil constituents and identifying potential beneficial applications [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470757622

    APA Style (7th edition)

  • Koralegedara, Nadeesha. Evaluating the constituent leaching from flue gas desulfurization gypsum (FGDG) under different leaching conditions, its geochemical interactions with main soil constituents and identifying potential beneficial applications. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470757622.

    MLA Style (8th edition)

  • Koralegedara, Nadeesha. "Evaluating the constituent leaching from flue gas desulfurization gypsum (FGDG) under different leaching conditions, its geochemical interactions with main soil constituents and identifying potential beneficial applications." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470757622

    Chicago Manual of Style (17th edition)

ucin1470757622
300
© 2016, some rights reserved.Creative Commons License Evaluating the constituent leaching from flue gas desulfurization gypsum (FGDG) under different leaching conditions, its geochemical interactions with main soil constituents and identifying potential beneficial applications by Nadeesha H Koralegedara is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.