Please join us at the MEGA Symposium 20-23 August 2012 in Baltimore where Jonathan Allen will present “Dissolved Metals Concentrations in FGD Wastewater Correlate with FGD Oxidation State” (Paper #99)
Dissolved Metals Concentrations in FGD Wastewater Correlate with FGD Oxidation State
by Jonathan O. Allen, Allen Analytics LLC, and Corey A. Tyree, Southern Company
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 SO2 and HAPs, but may generate wastewater containing Hg, Se, and other metals.
We report on 6-month field sampling campaigns to monitor trace metal chemistry in 15 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.