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Carbon source effects on nitrogen transformation processes and the quantitative molecular mechanism in long-term flooded constructed wetlands.

Authors :
Luo, Zhongxin
Li, Shengjie
Zhu, Xianfang
Ji, Guodong
Source :
Ecological Engineering. Nov2018, Vol. 123, p19-29. 11p.
Publication Year :
2018

Abstract

Graphical abstract Highlights • Adding an external source under low C/N can significantly improve nitrogen removal efficiency. • N transformation processes were coupled at the functional genes level. • The vertical distribution of the microbial community in CWs was a remarkable discrepancy. • Adding rice husk as a carbon source could be conducive to the complete nitrification process. Abstract The effect of adding rice husk as an electron donor on the genetic and metabolic diversity of denitrifying communities in a long-term flooded constructed wetland (D1) was compared with the control group without external carbon source addition (D2). The underlying molecular mechanisms responsible for nitrate removal were quantified under different nitrate loading rates. The results showed that D1 achieved higher and more stable removal efficiencies for NO 3 −-N (90–97%) and total nitrogen (73–87%) under different nitrate loading rates, which were approximately 10 times higher than those of D2. This corresponded with much higher absolute abundances of bacterial and nitrogen functional genes in D1 than D2. Additionally, the vertical distribution of microbial communities in D1 and D2 showed significant differences. This pattern suggested that adding rice husk in flooded CWs had beneficial effects on the denitrifying community. Quantitative response relationships and network analysis indicated that denitrification was the dominant nitrogen removal pathway. Moreover, the present study indicated that using rice husk as an external carbon source could be conducive to completing the nitrification process, which was first confirmed at the molecular level. The present study indicated that using rice husk as an external carbon source can significantly enhance denitrification rates and thus improve nitrogen removal in CWs for wastewater treatment process. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09258574
Volume :
123
Database :
Academic Search Index
Journal :
Ecological Engineering
Publication Type :
Academic Journal
Accession number :
131971033
Full Text :
https://doi.org/10.1016/j.ecoleng.2018.08.011