[Effect of Ferric Iron on Nitrogen Immigration and Transformation and Nitrous Oxide Emission During Simultaneous Nitrification Denitrification Process].

Effect of Fe(III) concentration on nitrogen immigration and transformation and nitrous oxide emission during the simultaneous nitrification denitrification (SND) process was investigated. Higher nitrogen removal efficiency was obtained when the Fe(III) concentration was 20 mg x L(-1), while lower nitrogen removal efficiency was observed when the Fe (III) concentration turned to 60 mg x L(-1). In addition, higher Fe(III) concentration significantly enhanced the N2O emission, as well as the N2O conversion ratio. This was mainly attributed to (1) the high concentration of nitrite accumulation during the oxic stage, which was caused by lower dehydrogenase activity at high Fe(III) concentration; (2) less PHB production during the anoxic stage, which would led to shortage of carbon source for denitrification in the following oxic stage. The results also showed that Fe(III) addition could improve the TP removal efficiency. TP removal efficiency increased with increasing Fe(III) concentration, mainly because of extra chemical reaction.