Demonstration Test of Iron Addition to an FGD Absorber to Enhance Flue Gas Mercury Removal

摘要

This paper documents results of a full-scale demonstration test of iron addition to a forced oxidation flue gas desulfurization (FGD) scrubber. Three potential beneficial effects of adding iron to the FGD reaction tank were evaluated: lowering mercury air emissions; lowering the concentrations of soluble or sub-micron-sized mercury particles in the FGD chloride purge water; and reducing selenate formation in FGD purge water. This technology may improve mercury removal by FGD systems, and could lower concentrations of mercury and selenium in FGD purge water more cost effectively than post-FGD water treating technologies currently available or being developed. Mercury and selenium removal from FGD wastewater is becoming more important as wastewater discharge regulations tighten.Results for selenium from the demonstration were promising, showing an apparent reduction of both total soluble selenium and of the selenate species in the FGD water. Results for mercury were mixed and difficult to draw conclusions from.