Abstract: A cyclic process for the removal of NOx from a NOx containing feed gas, and optionally removal mercury vapour and/or sulfur dioxide is provided. A process is also provided by which an iron chelate absorbent may be thermally regenerated.

Abstract: A process for removing contaminants from a waste gas stream comprises treating the waste gas stream to remove at least one of SO2 and NOx and to obtain a lean stream having a reduced level of at least one of SO2 and NOx and, contacting the lean gas stream with a mercury absorbent solution comprising permanganate to remove mercury vapour and to obtain a mercury lean stream and a mercury rich absorbent solution. The mercury rich absorbent solution may be subsequently treated on a batch basis to remove precipitated manganese dioxide and obtain a solution containing mercury ions.

Abstract: A cyclic process for the removal of NOx from a NOx containing feed gas, and optionally removal mercury vapour and/or sulfur dioxide is provided. A process is also provided by which an iron chelate absorbent may be thermally regenerated.

Abstract: Sulphur dioxide is removed from gas streams by contacting the gas stream with an absorbing medium containing an amine capable of forming an amine salt, heat stable salt and sulfite. The level of heat stable salt is selected such that during the regeneration process of the sulphur dioxide rich amine, the pH of the absorbing medium is at a selected level or below when the level of sulfite in the absorbing medium has been reduced to a specified value. The amine that absorbs the sulphur dioxide has a pKa less than that of sulfite. If the absorbent includes a diamine, then the spent absorbing medium is regenerated under conditions such that at least one amine group remains in salt form.