In a gasoline-contaminated site in Düsseldorf, Germany a two-year monitoring program was carried out to determine the presence, behavior, and fate of 12 gasoline additives in a total of 96 samples from 14 groundwater wells. The origin of contamination was suspected to be a gasoline spill at a gas station. Target compounds were methyl-tert-butyl ether (MTBE), its main degradation products, tert-butyl alcohol (TBA) and tert-butyl formate (TBF); other gasoline additives, oxygenate dialkyl ethers: Ethyl-tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE); aromatics: Benzene, toluene, ethylbenzene and xylenes (BTEX), and other compounds causing odor problems: Dicyclopentadiene and trichloroethylene. Purge and trap coupled with gas chromatography-mass spectrometry permitted detection of ng/L concentrations. Ninety of the 96 samples analyzed contained MTBE at levels varying between 0.01 to 645 microg/L. Five contaminated hot spots were identified with levels up to U.S. Environmental Protection Agency (U.S. EPA) drinking water advisory values (20-40 microg/L) and one of them doubling Danish suggested toxicity level of 350 microg/L at a depth of 11 m. No significant natural attenuation was found in MTBE degradation, although samples with high levels of MTBE contained 0.1 to 440 microg/L of TBA. These levels were attributed to its presence in the contamination source more than MTBE degradation. tert-Butyl alcohol was found to be recalcitrant in groundwater. In all cases, BTEX were at low concentrations or not detected, showing less persistence than MTBE. The monitoring of the contamination plume showed that the distribution of the MTBE and TBA in the aquifer formed a similar vertical concentration profile that was influenced by the groundwater flow direction.

In many drinking water treatment facilities with an activated carbon (AC) purification step, polar and hydrophilic molecules are substances of concern. Many of the current test methods for AC do not really reflect AC's adsorption capacity for these substances. To develop a fast and economically reasonable parameter that characterizes AC's ability to remove these compounds, three substances, namely diclofenac, nitrobenzene, and diatrizoate were investigated as test substances. A test set of different AC samples was created by reactivating an exhausted AC in three different ways. Additional AC samples were obtained by sampling different depths of a full-scale AC filter at regular intervals during the operation time of the filter. Several adsorption tests were performed with the three test substances, including adsorption isotherms in the concentration range mg/L, single-point adsorption tests in the concentration range μg/L, and pilot-scale fixed bed filter experiments. The results suggest that diatrizoate allows for a sensitive comparison of different AC samples. A characteristic figure, the 'diatrizoate number' was developed. This diatrizoate number allows for a sensitive, cheap, and quick comparison of different ACs. A similar survey with special focus on problematic substances present on site is recommended for other water treatment facilities.

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