Unraveling the active microbial populations involved in nitrogen utilization in a vertical subsurface flow constructed wetland treating urban wastewater.
The dynamics of the active microbial populations involved in nitrogen transformation in a vertical subsurface flow constructed wetland (VF) treating urban wastewater was assessed. The wetland (1.5m2) operated under average loads of 130gCODm-2d-1and 17gTNm-2d-1in Period I, and 80gCODm-2d-1and 19gTNm-2d-1in Period II. The hydraulic loading rate (HLR) was 375mmd-1and C/N ratio was 2 in both periods. Samples for microbial characterization were collected from the filter medium (top and bottom layers) of the wetland, water influent and effluent at the end of Periods I (Jun-Oct) and II (Nov-Jan). The combination of qPCR and high-throughput sequencing (NGS, MiSeq) assessment at DNA and RNA level of 16S rRNA genes and nitrogen-based functional genes (amoA and nosZ-clade I) revealed that nitrification was associated both with ammonia-oxidizing bacteria (AOB) (Nitrosospira) and ammonia-oxidizing archaea (AOA) (Nitrososphaeraceae), and nitrite-oxidizing bacteria (NOB) such as Nitrobacter. Considering the active abundance (based in amoA transcripts), the AOA population revealed to be more stable than AOB in both periods and depths of the wetland, being less affected by the organic loading rate (OLR). Although denitrifying bacteria (nosZ copies and transcripts) were actively detected in all depths, the denitrification process was low (removal of 2gTNm-2d-1for both periods) concomitant with NOx-N accumulation in the effluent. Overall, AOA, AOB and denitrifying bacteria (nosZ) were observed to be more active in bottom than in top layer at lower OLR (Period II). A proper design of OLR and HLR seems to be crucial to control the activity of microbial biofilms in VF wetlands on the basis of oxygen, organic-carbon and NOx-N forms, to improve their capacity for total nitrogen removal.
GESAD - Decentralized Sanitation Research Group, Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, Trindade, Florianópolis, Santa Catarina 88040-900, Brazil.
Catiane
C
Pelissari
GIRO Joint Research Unit IRTA-UPC, Research and Technology, Food and Agriculture (IRTA), Torre Marimon, E-08140, Caldes de Montbui, Barcelona, Catalonia, Spain.
Miriam
M
Guivernau
GIRO Joint Research Unit IRTA-UPC, Research and Technology, Food and Agriculture (IRTA), Torre Marimon, E-08140, Caldes de Montbui, Barcelona, Catalonia, Spain.
Marc
M
Viñas
INTELAB - Integrated Technologies Laboratory, Chemical and Food Engineering Department, Federal University of Santa Catarina, Trindade, Florianópolis, Santa Catarina 88040-900, Brazil.
Samara Silva
SS
de Souza
GEMMA - Environmental Engineering and Microbiology Research Group, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya-BarcelonaTech, c/ Jordi Girona, 1-3, Building D1, E-08034 Barcelona, Spain.
Joan
J
García
GESAD - Decentralized Sanitation Research Group, Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, Trindade, Florianópolis, Santa Catarina 88040-900, Brazil.
Pablo Heleno
PH
Sezerino
GEMMA - Environmental Engineering and Microbiology Research Group, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya-BarcelonaTech, c/ Jordi Girona, 1-3, Building D1, E-08034 Barcelona, Spain; ICRA, Catalan Institute for Water Research, Scientific and Technological Park of the University of Girona, Emili Grahit, 101, E-17003 Girona, Spain. Electronic address: cavila@icra.cat.
Cristina
C
Ávila
D000641:Ammonia; D001105:Archaea / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism; D019766:Genes, Archaeal; D005798:Genes, Bacterial; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D062065:Wastewater; D014871:Water Microbiology; D018508:Water Purification; D053833:Wetlands
D000641:Ammonia; D009584:Nitrogen; D012336:RNA, Ribosomal, 16S; D062065:Wastewater
Ammonia oxidizing archaea; Ammonia oxidizing bacteria; High organic load; High-throughput sequencing; Metabolically-active populations; Treatment wetland