Chemical and biochemical processes for NOx control from combustion off-gases

Nitrogen oxides (NOx) are major air pollutants as they have adverse effects on health and the environment. Various types of combustion equipment, including biosolids incinerators, are the sources of NO, emissions in the atmosphere. Various source control measures in the form of the use of low NOx burners and burner staging techniques, for example, are commonly practiced by the generators. Treatment processes such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are also widely used, especially by power plants. Newer processes involving chemical scrubbing of the flue gas have been under development for the past two decades and are being gradually introduced in full-scale commercial operation. This article provides a comprehensive review of recently developed chemical and biochemical processes for NOx control. Equations for the reaction rates, scrubber sizes, and chemical requirements are also presented.