Nitrogen and phosphorus removal performance and bacterial communities in a multi-stage surface flow constructed wetland treating rural domestic sewage

Amulti-stage surface flow constructedwetland (SFCW) is used to treat decentralized rural domestic sewage. The performance of a multi-stage SFCWlocated in Hunan, China, and the associated microbial community structures were investigated. The average removal rates of the multi-stage SFCW planted with Myriophyllum elatinoides were 1.0 g m(-2) d(-1), 0.84 g m(-2) d(-1), 61.3 mgm(-2) d(-1), and 85.3 mgm(-2) d(-1) for total nitrogen (TN), ammonia (NH4+), nitrate (NO3-), and total phosphorus (TP), respectively. Furthermore, the sediment and presence of plants were found to be important for the removal N and P. The average removal rates by sediment and plants were 196.6 mg N m(-2) d(-1) and 49.9 mg P m(-2) d(-1), 17.6 mg Nm(-2) d(-1) and 8.1 mg P m(-2) d(-1), respectively. The microbial community profiles demonstrated that Proteobacteria, Chloroflexi, Bacteroidetes, Firmicutes and Euryarchaeota were the predominant phyla in each stage and at different sampling times. The concentrations of NO3-, TP, TN, and NH4+, and the pH of the sediment and water had a significant effect on the presence of denitrifying bacteria in the anaerobic environment. Whereas, dissolved oxygen (DO) and redox potential (Eh) had a significant effect on the presence of nitrifying bacteria in the aerobic environment. This research strongly supports that the use of the multi-stage SFCW promotes bacterial diversity and changes bacterial community in the sediment. (C) 2019 Elsevier B.V. All rights reserved.