Removal of NOX Emitted from Nitric Acid Production with Biological Packing Tower

The nitric acid industry in the China is a major industrial source of NOx, an important contributor to the air pollution. This project aims at developing a technique for the removal of NOx by biological method. The use biological packing tower to remove NOx tail gas after alkali adsorption from nitric acid production was investigated by a field experiment. The biological packing tower, using slag as padding, in which inoculate sludge is the activated sludge from the aeration tank for wastewater treatment of the chemical fiber factory, after static and dynamic cultivating, and the forming of biological membrane, the denitrification bacteria can be observed by SEM. The study probed into the evaluation of bacteria immobilization methods, optimum operation parameters. The field experiment results shown that under the conditions of inlet gas NOx concentration 0.1~0.39%, a space velocity of 100 hr-1, controlling 7.0~8.2 pH of circulating liquid and liquid/gas ratio of lL/m3, obtained a reduction of NOx emission rate by 85%. Overall, the research showed new possibilities for using biological packing tower for the treatment NOx tail gas after chemical adsorption from nitric acid production.