Perfluorooctanoic acid and perfluorooctane sulfonate released from a waste water treatment plant in Bavaria, Germany

Perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and precursors and derivatives thereof have been employed as surfactants and anti-adhesives. PFOA and PFOS are environmentally persistent and the discharge of municipal waste waters is one of the principal routes of these compounds into the aquatic environment. In a previous study, the concentrations of PFOA and PFOS in grab samples collected from the waste water treatment plant (WWTP) of Bayreuth, a city of 72,000 inhabitants in Bavaria, Germany, during two periods showed considerable variability. For a better estimate of average mass flows, the surfactants were monitored (five samplings) from 16 March to 18 May 2007. In a second campaign, river water receiving the WWTP effluent was sampled twice a day for five consecutive days. Quantitative analysis was done by stable-isotope dilution, pre-cleaning, and pre-concentration by solid-phase extraction, and liquid chromatography followed by electrospray ionization/tandem mass spectrometry. The mass flows of PFOA and PFOS through the WWTP were determined. PFOA is fully discharged into the river, while about half of PFOS is retained in the sewage sludge. The average daily mass load of the river Roter Main by the WWTP of Bayreuth is about 1.2 +/- 0.5 g PFOA and 5 +/- 2 g PFOS, with variations of up to 140% within one day. Overall, the total annual release to the rivers of Germany may be in the range of several hundred kilograms of PFOA and several tons of PFOS.