Gaseous mercury re-emission from wet flue gas desulfurization wastewater aeration basins: A review

• Published in: Journal of hazardous materials Vol. 420; p. 126546
• Main Authors: Hsu, Che-Jung, Atkinson, John D., Chung, Adrienne, Hsi, Hsing-Cheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2021
• Subjects: Coal-fired power plant; Flue gas desulfurization; Mercury; Re-emission; Coal-fired power plant; Flue gas desulfurization; Mercury; Re-emission
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126546

Wet flue gas desulfurization (WFGD) simultaneously removes Hg and SO2 from coal-fired power plant flue gas streams. Hg0 re-emission occurs when the dissolved Hg(II) is converted to a volatile form (i.e., Hg0) that can be subsequently emitted into the ambient air from WFGD wastewater aeration basins. Others have shown that Hg0 re-emission depends on pH, temperature, ligands (Cl, Br, I, F, SO32-, SO42-, NO3-, SCN-, and ClO-), O2, minerals (Se and As), and metals (Fe and Cu) in WFGD wastewater. Still others have shown Hg0 re-emission restriction via inhibitor addition (adsorbents and precipitators). This is the first review that summarizes the complex and inconsistently reported Hg0 re-emission mechanisms, updates misconceptions related to Hg(II) complexation and reduction, and reviews applications of inhibitors that convert aqueous Hg(II) into stable solid forms to prevent gaseous Hg0 formation and release. [Display omitted] •Hg0 wet flue gas desulfurization (WFGD) re-emission mechanisms were summarized.•Effects of various aqueous parameters on Hg0 re-emission were reviewed.•Inhibitor applications on Hg0 re-emission restriction were compared.•Misconceptions related to Hg(II) complexation and reduction were updated.•Critical and future perspectives on Hg0 re-emission from WFGD water were presented.