title: Changes in the planktonic microbial community during residence in a surface flow constructed wetland used for tertiary wastewater treatment.
abstract: Suspended particles are a major constituent of municipal wastewater and generally contain high levels of bacteria, including human pathogens. Discharge of these particles of anthropogenic nature can have profound effects on receiving aquatic ecosystems and mitigation of these effects requires additional polishing of treated municipal wastewater. Previously it was shown that surface flow constructed wetlands are effective in improving water quality by reducing the numbers of fecal indicator organisms. However, fecal indicator organisms represent only a minor fraction of the total planktonic bacterial community and knowledge on the effects of these constructed wetlands on the composition and functioning of the entire planktonic bacterial community is limited. The aim of this descriptive study was therefore to identify changes in the planktonic bacterial community during residence of secondary treated municipal wastewater in a full-scale surface flow constructed wetland. To this purpose water samples were taken in which the bacterial community composition and functioning were analyzed using FISH, DGGE and BIOLOG. Surprisingly, the bacterial abundance at the inflow of the constructed wetland was relatively low compared with more natural surface waters. However, the inflowing bacterial community showed high metabolic activity and functional diversity. During residence in the surface flow constructed wetland the bacterial abundance doubled, but decreased in metabolic activity and functional diversity. Shifts in the community composition indicate that these changes are related to turn-over of the bacterial community. The planktonic bacterial community in the effluent of the constructed wetland closely resembled natural bacterial communities in urban and agricultural ditches. Based on these observations we conclude that constructed wetlands are capable to mitigate possible impacts of the particle load in treated wastewaters by transforming the anthropological bacterial community to a bacterial community resembling more "natural" surface waters.
authors: University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Department of Aquatic Ecology and Ecotoxicology, Science Park 904, 1098 XH Amsterdam, The Netherlands; Stichting Waternet, Korte Ouderkerkerdijk 7, 1096 AC Amsterdam, The Netherlands. Electronic address: bram.mulling@gmail.com.
authors: Bram T M
authors: BT
authors: Mulling
authors: A Marieke
authors: AM
authors: Soeter
authors: Harm G
authors: HG
authors: van der Geest
authors: Wim
authors: W
authors: Admiraal
mesh_terms: D018407:Bacterial Physiological Phenomena; D064307:Microbiota; D009426:Netherlands; D010933:Plankton / Q000502:physiology*; D006109:Poaceae; D016133:Polymerase Chain Reaction; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology*; D053833:Wetlands
chemical_list: D062065:Wastewater
keywords: BIOLOG; Constructed wetland; DGGE; FISH; Planktonic bacteria; Suspended particles