Nitrogen and phosphorus removal performance and bacterial communities in a multi-stage surface flow constructed wetland treating rural domestic sewage
2020
Li, Xi | Li, Yuyuan | Lv, Dianqing | Li, Yong | Wu, Jinshui
A multi-stage surface flow constructed wetland (SFCW) is used to treat decentralized rural domestic sewage. The performance of a multi-stage SFCW located 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 mg m⁻² d⁻¹, and 85.3 mg m⁻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 N m⁻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.
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