Flue gas denitrification refers to the reduction of generated NOX to N2, so as to remove NOX from the flue gas. According to the treatment process, it can be divided into wet denitrification and dry denitrification. Mainly include: acid absorption method, alkali absorption method, selective catalytic reduction method, selective non-catalytic reduction method, adsorption method, ion activation method. Some scientific researchers at home and abroad have also developed methods for treating NOX emissions with microorganisms.

Since NOx in the flue gas emitted from the combustion system is more than 90% NO, and NO is hardly soluble in water, the wet treatment of NOx cannot be performed by a simple washing method. The principle of flue gas denitrification is to use oxidant to oxidize NO to NO2, and the generated NO2 is then absorbed by water or alkaline solution to achieve denitrification. The O3 oxidation absorption method oxidizes NO with NO3 to NO2 and then absorbs with water. The product HNO3 liquid of this method needs to be concentrated, and O3 needs high voltage preparation, and the initial investment and operating costs are high. The ClO2 redox process ClO2 oxidizes NO to NO2 and then reduces the NO2 to N2 with aqueous Na2SO3 solution. The method can be combined with the wet desulfurization technology using NaOH as a desulfurizer. The desulfurization reaction product Na2SO3 can be used as a reducing agent for NO2. The denitration rate of ClO2 method can reach 95, and can desulfurize at the same time, but the price of ClO2 and NaOH is higher, the operating cost increases.