title: Impact of COD/N ratio on nitrous oxide emission from microcosm wetlands and their performance in removing nitrogen from wastewater.
abstract: Constructed wetlands (CWs) are considered to be important sources of nitrous oxide (N(2)O). In order to investigate the effect of influent COD/N ratio on N(2)O emission and control excess emission from nitrogen removal, free water surface microcosm wetlands were used and fed with different influent. In addition, the transformation of nitrogen was examined for better understanding of the mechanism of N(2)O production under different operating COD/N ratios. It was found that N(2)O emission and the performance of microcosm wetlands were significantly affected by COD/N ratio of wastewater influent. Strong relationships exist between N(2)O production rate and nitrite (r=0.421, p<0.01). During denitrification process, DO concentration crucially influences N(2)O production rate. An optimal influent COD/N ratio was obtained by adjusting external carbon sources for most effective N(2)O emission control and best performance of the CWs in nitrogen removal from wastewater. It is concluded that under the operating condition of COD/N ratio=5, total N(2)O emission is minimum and the microcosm wetland is most effective in wastewater nitrogen removal.
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China. wujuan410@yahoo.com.cn
authors.forename: Juan
authors.initials: J
authors.lastname: Wu
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Wenlin
authors.initials: W
authors.lastname: Jia
authors.forename: Huijun
authors.initials: H
authors.lastname: Xie
authors.forename: Roy R
authors.initials: RR
authors.lastname: Gu
authors.forename: Cong
authors.initials: C
authors.lastname: Li
authors.forename: Baoyu
authors.initials: B
authors.lastname: Gao
mesh_terms: D003198:Computer Simulation; D007220:Industrial Waste / Q000032:analysis / Q000517:prevention & control*; D008956:Models, Chemical; D009584:Nitrogen / Q000737:chemistry* / Q000302:isolation & purification*; D009609:Nitrous Oxide / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D009609:Nitrous Oxide; D009584:Nitrogen; D010100:Oxygen