Removal of Mercury from Stack Gases by Activated Carbon

On combustion, the trace elements in the incinerator feed stream are partitioned between the bottom ash (slag) stream, and a flue gas stream containing suspended fly ash and vapors of volatile elements or compounds. A further partitioning of the flue gas stream takes place in the particulate emission control devices that efficiently remove larger fly ash particles but are less efficient for vapors and finer particles. Ash from the bottom of the combustion chamber and ash removed by the particulate control devices are flushed with water to ash ponds, where elements may be leached from the ash and enter the aquatic environment in runoff. Small particles and vapors are discharged to atmosphere through exhaust stacks and enter the terrestrial and aquatic environments by wet or dry deposition.