Attenuation of Wastewater-Derived Contaminants in an Effluent-Dominated River

Although wastewater-derived chemical contaminants undergo transformation through a variety of mechanisms, the relative importance of processes such as biotransformation and photolysis is poorly understood under conditions representative of large rivers. To assess attenuation rates under conditions e...

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Bibliographic Details
Published in:Environmental science & technology 2006-12, Vol.40 (23), p.7257-7262
Main Authors: Fono, Lorien J, Kolodziej, Edward P, Sedlak, David L
Format: Article
Language:English
Subjects:
Biotransformation
Chemical contaminants
Drug Residues - analysis
Effluents
Environmental Monitoring - statistics & numerical data
Gas Chromatography-Mass Spectrometry
Rivers
Rivers - chemistry
Sewage - analysis
Texas
Water Movements
Water Pollutants, Chemical - analysis
Water pollution
Water treatment
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Summary:Although wastewater-derived chemical contaminants undergo transformation through a variety of mechanisms, the relative importance of processes such as biotransformation and photolysis is poorly understood under conditions representative of large rivers. To assess attenuation rates under conditions encountered in such systems, samples from the Trinity River were analyzed for a suite of wastewater-derived contaminants during a period when wastewater effluent accounted for nearly the entire flow of the river over a travel time of approximately 2 weeks. While the concentration of total adsorbable organic iodide, a surrogate for recalcitrant X-ray phase contrast media in wastewater, was approximately constant throughout the river, concentrations of ethylenediamine tetraacetate, gemfibrozil, ibuprofen, metoprolol, and naproxen all decreased between 60% and 90% as the water flowed downstream. Comparison of attenuation rates estimated in the river with rates measured in laboratory-scale microcosms suggests that biotransformation was more important than photolysis for most of the compounds. Further evidence for biotransformation in the river was provided by measurements of the enantiomeric fraction of metoprolol, which showed a gradual decrease as the water moved downstream. Results of this study indicate that natural attenuation can result in significant decreases in concentrations of wastewater-derived contaminants in large rivers.
ISSN:0013-936X
1520-5851
DOI:10.1021/es061308e