Nitrous Oxide Emission and Control in Biological and Chemical Denitrification

Nitrous oxide (N2O) is considered as a greenhouse gas for a long time, in fact, N(2)Ois also an important propellant in the area of aeronautics and astronautics. More and more attention are attracted to the preparation of N2O in western developed countries. A large amount of N2O could be produced in the process of biological and chemical denitrification, moreover, N2O can be emitted in substantial amounts during nitrogen removal in wastewater treatment. However, limited researches on the collection and utilization of N2O as clean energy are reported in China. In this paper, the pathway of N2O emission in biological nitrogen removal, as well as the mechanisms and influence factors are introduced. In the mean time, the contribution of chemodenitrification in the emission of N2O, especially the role of Fe(II), is also discussed. The reutilization of N2O emitted in nitrogen removal process as resources are outlined in the final part of this paper. As the process of chemodenitrification can accumulate a great quantity of N2O more rapidly and more effectively in comparison with biological process, the research in the future should be focused on the mechanisms and influence factors of the production of N2O by chemodenitrificaition. Further research is urgently required in the area of utilization of N2O.