Constructed wetlands (CWs) are low-energy, low-cost and easy to operate artificial systems, widely used in the treatment of domestic wastewater, eutrophic river water, and livestock and poultry breeding wastewater. Microorganisms are highly abundant in these wetlands, and they play a dominant role in the wetland nitrogen (N) cycle. Microbial activities in the CWs mainly comprise nitrification and denitrification, which are the dominant pathways of N removal in CWs.

Researchers in the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) employ quantitative PCR (qPCR), chlorate inhibition method and acetylene (C₂ H₂) inhibition method to the analysis, including the nitrification and denitrification rates and their association with the appropriate functional gene abundances ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), nirK, nirS and bacterial 16S rRNA, and functional gene response to environmental factors in CWs.

The team found AOB outnumber AOA, and nirK outnumber nirS throughout the year in SFCWs plant with Myriophyllum elatinoides. PNR was higher in the summer, while PDR gradually increased seasonal progression.

The abundances of AOB and nirK were strongly correlated with PNR and PDR, respectively, further indicating that they play a vital role in N cycling in M. elatinoides SFCWs.

Besides, these results expand our understanding of the relative changes in nitrification and denitrification processes underpinning the high rate of N removal in M. elatinoides SFCWs. As this study suggests, M. elatinoides SFCWs can be used to treat N-rich wastewater.

This research was supported by funding from the the National Natural Science Foundation of China (41601268), the National Science and Technology Supporting Project (2014BAD14B00), and the Ministry of Water Resources Public Service Industry, a Special Fund (201501055). Public Service Technology Center, Institute of Subtropical Agriculture, and the Chinese Academy of Sciences provided our team for experimental platform.

The study entitled “Seasonality distribution of the abundance and activity of nitrification and denitrification microorganisms in sediments of surface flow constructed wetlands planted with Myriophyllum elatinoides during swine wastewater treatment” has been published in the January 2018 issue of Bioresource Technology, details could be found at https://www.sciencedirect.com/science/article/pii/S0960852417310064.

Contact: LI Xi

E-mail: lixi@isa.ac.cn 

Institute of Subtropical Agriculture, Chinese Academy of Sciences