Caffeine, an Anthropogenic Marker for Wastewater Contamination of

Environ. Sci. Technol. 2003, 37, 691-700

Caffeine, an Anthropogenic Marker for Wastewater Contamination of Surface Waters IGNAZ J. BUERGE,* THOMAS POIGER, ¨ LLER, A N D M A R K U S D . MU HANS-RUDOLF BUSER Plant Protection Chemistry, Swiss Federal Research Station, CH-8820 Wa¨denswil, Switzerland

The suitability of caffeine as a chemical marker for surface water pollution by domestic wastewaters was assessed in this study. Caffeine concentrations in influents and effluents of Swiss wastewater treatment plants (WWTPs, 7-73 and 0.03-9.5 µg/L, respectively) indicated an efficient elimination of 81-99.9%. Corresponding loads in untreated wastewater showed small variations when normalized for the population discharging to the WWTPs (15.8 ( 3.8 mg person-1 d-1), reflecting a rather constant consumption. WWTP effluent loads were considerably lower (0.06 ( 0.03 mg person-1 d-1), apart from installations with low sludge age (e5 d, loads up to 4.4 mg person-1 d-1). Despite the efficient removal in most WWTPs, caffeine was ubiquitously found in Swiss lakes and rivers (6-250 ng/ L), except for remote mountain lakes (99%); 13C3-labeled caffeine, used as internal standard, was from Cambridge Isotope Laboratories, Cambridge, MA (courtesy of C. Schaffner, EAWAG, Switzerland). Water Samples. Wastewater samples were obtained from municipal WWTPs located in the region of Greifensee and Zu ¨richsee, Switzerland. These installations operate with three or four stages, a mechanical, biological (activated sludge, mostly with nitrification and partially with denitrification), VOL. 37, NO. 4, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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TABLE 1. Literature Data of Caffeine Concentrations in WWTPs and Natural Waters sample

caffeine concentration

WWTPs, influent water

20-300 µg/L (Canada) 20 µg/L (USA) 147 ( 76 µg/L (Germany) 0.06-0.08 µg/L (USA) 6.7 µg/L (USA) 0.19 ( 0.09 µg/L, up to 1.9 µg/L (Germany) 2 µg/L (Sweden) 10-100 ng/L (USA) 3-1440 ng/L, median 160 ng/L (USA) 13 ( 28 ng/L, up to 115 ng/L (USA) 10-47 ng/L (USA) median 81 ng/L, up to 6 µg/L (USA) 130-370 ng/L (USA) median 530 ng/L, up to 880 ng/L (Germany)