Occurrence, Transport, and Fate of Pharmaceuticals and Other Emerging Contaminants Present in Wastewater
To determine which chemicals are present in wastewater effluent, and quantify their persistence downstream from wastewater treatment.
At ten locations, samples were collected upstream and at two sites downstream from the WWTP discharge, as well as from the effluent pipe. The stream samples were depth and width integrated composites, while the effluent was a grab sample. To quantify the persistence of these chemicals, a Lagrangian dye tracer study was conducted at two locations prior to sampling to determine the stream's travel time to the pre-selected sampling locations. This ensured the same parcel of water was sampled at all stations, and enabled the calculation of pseudo first-order rate constants. The samples were analyzed for 110 chemicals using three different analytical methods: (1) continuous liquid/liquid extraction followed by gas chromatography/ mass spectrometry (GC/MS) analysis for 66 common wastewater chemicals; (2) solid phase extraction (SPE) followed by liquid chromatography/mass spectrometry positive-ion electrospray (LC/MS-ESI(+)) analysis for 21 pharmaceuticals; and (3) SPE followed by LC/MS-ESI(+) analysis for 23 antibiotics. The samples were also analyzed for two microbial indicators, E. coli and enterococci, using U.S. EPA Methods 1103.1 and 1600, both traditional methods utilizing filtration and incubation.
Of the 110 compounds investigated in effluents and surrounding surface waters, 78 were detected at least once. Different chemicals exhibited diverse environmental persistence. Some (e.g., galaxolide and tonalide) were short-lived, and exhibited statistically significant differences in concentration between the upstream and effluent, between the effluent and first downstream sample, as well as between the effluent and the second downstream sample. Others (e.g., caffeine) were ubiquitous and exhibited no statistically significant difference in concentration between any of the sampling sites within a given location.
The preliminary results for the initial Lagrangian sampling indicated that there was agreement in the general classifications of compound persistence, but the absolute value for the rate constant for a given compound could vary by an order of magnitude between the two streams.
This project supplied information on the occurrence and fate of pharmaceuticals and other wastewater derived compounds. This information is being applied in other projects that are (1) evaluating the compounds for use as indicators of human fecal contamination; and (2) ascertaining which chemicals are present in finished drinking water.
Susan Glassmeyer at email@example.com