Vegetated treatment wetlands have been built around the world for the removal of nutrients, organic matter and metals, but only recently have engineers considered their use for the treatment of trace organic contaminants. Most attempts to understand the transformation of trace organic compounds in vegetated treatment wetlands have relied upon monitoring of inlet and outlet concentrations of target compounds as a means of estimating removal rates. To provide insight into mechanisms of contaminant removal, a pilot-scale vegetated treatment wetland and laboratory microcosms were used in conjunction with characterization of microbial communities via next-generation phylogenetic sequencing to assess processes controlling the biotransformation of ten wastewater-derived pharmaceutical compounds in vegetated wetlands. Vegetation collected from the litter accumulated in the pilot-scale wetland was used as a source of carbon and as a means of inoculating laboratory microcosms. Analysis of 16S rRNA gene profiles of the vegetation-associated biofilms allowed for tracking of microbial community evolution from the time of collection to the end of the seven-day microcosm studies. Microbial communities in all samples were dominated by Bacteroidetes, Firmicutes, and a, �, and ? Proteobacteria. Microcosms established with different terminal electron acceptors were used to assess the rates of biotransformation and products of biotransformation reactions under different conditions. Differences observed in contaminant transformation rates and products among microcosms suggest that zones where vegetation undergoes decay in the absence of oxygen play an important role in the biotransformation process. This information may by used to optimize the removal of trace organic compounds in vegetated treatment wetlands by adjusting maintenance activities to foster conditions conducive to the highest rates of contaminant biotransformation.

Optimizing vegetated treatment wetlands for the transformation of trace organic compounds

248th National Meeting (2014)

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