Abstract
Many technologies by wet method have been unrer the develop-ment with much efforts to respond to governmental regulation which has been officia-lized in 1973 with environmental standard of 0.02ppm effective in 1978.
Since it has been made clear that the catalitic reduction with NH3 should have limitations, reliable performances of wet method have been becomming more attractive.
Basic principle of wet method can be divided into five groups applying either direct removal of NO or NOx, or combinations fo gas phase oxidation of NO to higher oxides and liquid phase chemical reactions.
The most serious point of interests at present are liquid waste treatment and simultaneous removal of SOx. There are more than 30 companies engaged in extensive development, some of them with sponsorships from electric power companies and or subsidy from goverment, depending on one of those or combination of two or three principles, however, because of flexibilities and freedom of wet method, it is still difficult to evaluate the suitabiltty or adoptabiliity of each process to each of stational NOx sources which also have wide range of variation.
In this report, basic principles and efficiencies of NOx removal are compared to some extents, major activities of development are introduced, and the characteristic points important for air pollution control processes and plants are discussed.
