Mercury Removal from Waste Incineration Flue Gas: Heterogeneous Oxidation and Capture by Waste-Derived Fly Ashes.

During waste incineration, all Hg-content is released primarily as elemental mercury (Hg0) which passes into the flue gas and is gradually oxidized. Mainly HgCl2 is formed, by both homogeneous and heterogeneous reactions. Some degree of Hg removal is achieved by existing conventional air pollution control devices (APCDs), normally used to control NOx, SO2, and dust emissions. In this study, three samples of fly ashes from boiler and ESP (characterized by composition, surface area and carbon content) derived from MSW incineration were assessed for mercury removal under MSW incineration conditions in a laboratory scale, using a fixed-bed reactor packed with fly ash. The results obtained showed that unburnt carbon content, composition of flue gas (e.g. mainly HCl and SO2 content) and operating temperature are important variables controlling capture of mercury by fly ash