Comparative analysis of upward and downward vertical flow constructed wetlands on the nitrogen removal and functional microbes treating wastewater containing Ag nanoparticles. (15th January 2021)

• Record Type: Journal Article
• Authors: Cao, Chong; Huang, Juan; Yan, Chun-ni; Ma, Yi-xuan; Xiao, Jun; Zhang, Xin-xin
• Is Part Of: Journal of environmental management. Volume 278:Part 2(2021)
• Publication Date: 2021-01-15
• Subjects: Silver nanoparticles -- Nitrogen removal -- Functional genes -- Flow directions -- Constructed wetlands; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2020.111573
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: This study investigated impacts of silver nanoparticles (AgNPs) on nitrogen removal within constructed wetlands (CWs) with different flow directions. The obtained results showed that addition of AgNPs at 0.5 and 2 mg/L significantly inhibited NH4 + -N removal, resulting from lower abundances of functional genes ( amoA and nxrA ) within CWs. And higher abundances of amoA and nxrA genes at 0.5 mg/L were observed in downward flow CW, leading to better NH4 + -N removal, compared to upward flow CW. Besides, nitrifying genes amoA and nxrA in upward flow CW at 2.0 mg/L exhibited higher than downward flow CW, explaining better NH4 + -N removal in upward flow CW. 0.5 mg/L AgNPs significantly declined NO3 − -N and TN removal, resulted from decreasing abundances of nirK, nirS and nosZ . In contrast, abundances of nirK, nirS and nosZ genes had slightly lower or higher than before adding AgNPs in upward flow CW, leading to lower NO3 − -N and TN effluent concentrations. High throughput sequencing also indicated the changes of functional bacterial community after exposing to AgNPs. Graphical abstract: Image 1 Highlights: AgNPs evidently reduced nitrogen removal, relating with AgNPs concentrations. Flow directions significantly affected AgNPs impacts. Inhibition on the functional genes caused the lower nitrogen performance. Upflowed CW had better resistance ability to AgNPs exposure than Downflow CW.