Carola Graf

TZW Technologiezentrum Wasser, Carlsruhe, Baden-Württemberg, Germany

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Publications (2)4.19 Total impact

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    ABSTRACT: Six trace contaminants (acesulfame (ACE), sucralose (SUC), carbamazepine (CBZ), diatrizoic acid (DTA), 1H-benzotriazole (BTZ) and its 4-methyl analogue (4-TTri)) were traced from wastewater treatment plants (WWTPs) to receiving waters and further to riverbank filtration (RBF) wells to evaluate their prediction power as potential wastewater markers. Furthermore, the persistence of some compounds was investigated in advanced wastewater treatment by soil aquifer treatment (SAT). During wastewater treatment in four conventional activated sludge WWTPs ACE, SUC, and CBZ showed a pronounced stability expressed by stable concentration ratios in influent (in) and effluent (out) (ACE/CBZ: in45, out40; SUC/CBZ: in1.8, out1.7; and ACE/SUC: in24, out24). In a fifth WWTP, additional treatment with powdered activated carbon led to a strong elimination of CBZ, BTZ, and 4-TTri of about 80% and consequently to a distinctive shift of their ratios with unaffected compounds. Data from a seven month monitoring program at seven sampling locations at the rivers Rhine and Main in Germany revealed the best concentration correlation for ACE and CBZ (r(2) = 0.94) and also a good correlation of ACE and CBZ concentrations to BTZ and 4-TTri levels (r(2) = 0.66 to 0.82). The comparison of ratios at different sampling sites allowed for the identification of a CBZ point source. Furthermore, in Switzerland a higher consumption of SUC compared to Germany can be assumed, as a steadily increasing ACE/SUC ratio along the river Rhine was observed. In RBF wells a good correlation (r(2) = 0.85) was again observed for ACE and CBZ. Both also showed the highest stability at a prolonged residence time in the subsurface of a SAT field. In the most peripheral wells ACE and CBZ were still detected with mean values higher than 36 µg L(-1) and 1.3 µg L(-1), respectively. Although SUC concentrations in wastewater used for SAT decreased by more than 80% from about 18 µg L(-1) to 2.1 µg L(-1) and 3.5 µg L(-1) in these outlying wells, the compound was still adequate to indicate a wastewater impact in a qualitative way.
    Journal of Environmental Monitoring 02/2011; 13(4):966-73. · 2.09 Impact Factor
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    ABSTRACT: In this paper, results of an extensive monitoring programme for pharmaceutical residues in the river Rhine are presented. For one decade (1997 until 2006), the occurrence of widely used human pharmaceuticals like analgesics, lipid regulators, antiepileptics and others has been studied at four locations along the river Rhine. The results of more than 500 analyses clearly prove that compounds such as carbamazepine or diclofenac are regularly found in the river Rhine in concentrations up to several hundred ng per litre. Combining concentration levels with data on water flow enables the calculation of transports, which e.g. for carbamazepine or diclofenac were in the range of several tons per year. The evaluation of the long-term monitoring data shows that only a slight decrease in concentration levels as well as in annual transports can be observed and thus the contamination of the river Rhine by pharmaceutical residues during the last decade has to be regarded as almost constant. Seasonal variations can be detected for bezafibrate, diclofenac and ibuprofen, for which the concentrations are much lower in the summer months. A more effective removal during wastewater treatment in the warmer periods of the year seems to be the major reason for those variations. For carbamazepine, no comparable seasonal effect can be found.
    Journal of Environmental Monitoring 06/2008; 10(5):664-70. · 2.11 Impact Factor