Comparison of interannual removal variation of various constructed wetland types

Department of Biodiversity and Environmental Management, Faculty of Biologic and Environmental Sciences, University of León, Campus de Vegazana s/n, E-24071 León, Spain.
Science of The Total Environment (Impact Factor: 4.1). 05/2012; 430:174-83. DOI: 10.1016/j.scitotenv.2012.04.072
Source: PubMed


Seven mesocosm-scale (1m(2)) constructed wetlands (CWs) of different configurations were operated outdoors for thirty-nine months under the same conditions to assess their ability to remove organic matter and nutrients from urban wastewaters. CWs differed in some design parameters, namely the presence of plants, the species chosen (i.e., Typha angustifolia or Phragmites australis), the flow configuration (i.e., surface flow or subsurface flow) and the presence/absence of a gravel bed. It was observed that, in general, removal efficiencies decreased with the aging of the system and that seasonality had a great influence on CWs. A comparison was made in order to figure out which kind of CW was more efficient for the removal of every pollutant in the long term. Planted systems were clearly better than unplanted systems even in winter. Efficiency differences among CWs were not extremely great, especially after a few years. However, some types of CWs were more adequate for the removal of certain pollutants. The effect of the aging on the main parameters involved in pollutant removal in CWs (temperature, pH, conductivity, dissolved oxygen concentration and redox potential) was assessed. The efficiency of CWs should not be evaluated based on short monitoring periods (1-2 years) after the start-up of the systems, but on longer periods.

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    • "Wetlands can be used as a secondary or tertiary treatment step, following chemical and/or biological treatments, and rely upon natural processes in shallow water or temporarily flooded land that is able to support aquatic life [18]. These systems tend to be less resource-intensive than conventional wastewater treatment plants [5,18], and have been used successfully for treatment of municipal sewage in small communities, as well as for some industrial wastewaters [19]. While most research has focused on the use of wetlands for reduction of nutrients and biochemical oxygen demand (BOD) in water bodies receiving runoff from agricultural or urban sources [6,20], recent studies have shown that these systems might remove PPCPs as well [1,6,18,21]. "
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