Throughout history, man has disposed of ‘municipal solid waste’ via incineration and landfilling. As the population and waste generated per capita increased, and concomitantly the available landfill space diminished, the favored and sometimes only waste disposal option was incineration. Air pollution is one of the costs society bears for incineration. Municipal waste combustion liberates acid gas emissions such as SO x , HCl, and NO x . Flue gas scrubbing and alkaline sorbent injection technologies are typically used to neutralize acidic, SO x and HCl emissions. Staged combustion and more frequently add-on, ‘post-combustion’ control technologies are used to reduce nitrogen oxide emissions. This section of the journal will cover the use of ‘add-on control technologies’ for reducing nitrogen oxide emissions from municipal waste incinerators. A detailed technology description along with process benefits and limitations are discussed. Finally, a generic economic analysis and a list of post-combustion NO x control applications are enclosed.