(3) Introduction of Denitrifying Equipment

3.progress in Technology-Based Controls

Ambient NOx standards were provided by the notification issued by the Environment Agency in 1973 that the daily average of hourly values should not exceed 0.02ppm (Amended in 1978 into “within or below the range of 0.04ppm to 0.06ppm). Since these standards were the most stringent, private enterprises were confronted with a formidable task -the development of air denitrification processes.
Around 1975, the national government and private enterprises had opposite opinions on the evaluation of the stage of development of denitrification techniques. While the national government considered them as feasible on a technical basis, private enterprises insisted that some difficulties remained in their realization, Denitrification processes such as the dry ammonia-catalytic-reduction system have been put into practical use since 1978 and had been installed at 7 plants in Yokkaichi since 1990.