In response to the widespread installation of wet flue gas desulfurization (wFGD) systems, EPA is expected to revise wastewater effluent guidelines for the Steam Electric Power Generating industry. Wet FGD units effectively control atmospheric emissions of SO_2 and HAPs, but may generate wastewater containing Hg, Se, and other metals. We report on 5-month field sampling campaigns to monitor trace metal chemistry in 14 wFGD systems. Partitioning of trace metals resulted in order of magnitude changes in the concentrations of dissolved Hg and Se; these were in the ranges 0-100 ppb and 80 - 15,000 ppb, respectively. Dissolved phase concentrations of Hg and Se correlated with the overall oxidation state of the FGD system, as indicated by the oxidation-reduction potential (ORP). These results suggest that wastewater treatment system load may be reduced by operating wFGD units to minimize dissolved metal concentrations.
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