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Organic micropollutants in the aquatic environment - interdisciplinary concepts for assessment and removal

Final Activity Report Summary - AQUABASE (Organic micropollutants in the aquatic environment - interdisciplinary concepts for assessment and removal)

The project focussed on the concerted effort of an international, multidisciplinary group of researchers upon the topic of organic micropollutants in the aqueous environment. Our goal was to provide improved understanding regarding the fate of civilisation-related chemicals in the aquatic environment and ways to control it. To this end, the project utilised the expertise of different disciplines in order to:

1. develop and improve analytical methods
2. detect and identify organic micropollutants
3. investigate their fate and behaviour in different systems
4. evaluate their effects on mitigation technologies and
5. test mitigation technologies.

The programme focussed on endocrine disrupters, however a broader group of micropollutants, including antibiotics, other pharmaceuticals and pesticides was also considered. Chemical analytical methods for cytostatic compounds and their metabolites were successfully developed. They involved two mass spectrometry methods, whose limits of detection were established in the low ng/L range. The proposed methodology was applied to hospital wastewater, wastewater treatment plant effluent and water samples from ecotoxicity tests.

Analytical procedures were also established for very polar active constituents in pain killers, i.e. the phenanzone like compounds. Based on this tool, a variety of oxidation products formed through ozonation could be identified. Interestingly, some of these intermediates were also generated through biodegradation, as was proven through adequate experimentation and wastewater treatment plant sampling.

Nonylphenol (NP) was investigated in different fate studies assessing its behaviour in a membrane bioreactor (MBR), sludge amended soils and soil-plant systems. The use of radio-labelled substances was a key technique during these investigations. In the MBR fate study with 14C-NP the highest amount of radioactivity, namely 42.2 %, was recovered as metabolites of NP in the effluent, followed by the sorption to the component parts, which represented 33.7 % and the excess sludge, equal to 21.3%. Volatilisation and mineralisation were insignificant. In these studies degradation products of NP were identified as alkyl chain oxidation compounds.

In addition, the influence of sludge treatment on the fate of NP in sludge amended soils was studied. The shares of extractable or bound residues, either parent compound or metabolites, and leaching potential were correlated to the sludge treatment method. In comparison to non-conditioned sludge, freeze-thawing and liming increased the fraction of extractable residues. The use of cationic polymer decreased the NP leaching potential while liming increased it. Metabolisation of NP was mainly accomplished by soil endogenous microbial species.

With respect to groundwater protection the behaviour of various pharmaceuticals during soil passage was investigated. This included the determination of the sorption behaviour on different types of soil, as well as soil column experiments. The results showed that the selected substances possessed low sorption coefficients and little retention in the unsaturated zone. This rendered them prone to percolate through the groundwater.

In terms of ecotoxicity and environmental effects, the partitioning of compounds in multi-phase systems such as water, sediment, food and organisms, is recognised as an important factor influencing the bioavailability for and uptake by organisms. A comprehensive investigation was carried out for the hormone 17alpha-ethinylestradiol (EE2). The experiments referred to different trophic levels and quantified bioconcentration and bioaccumulation of the compound in different organisms. It was shown that EE2 concentrated to a great extent in algae, on which water fleas were feeding. The fewer algae available, the higher was the bioaccumulation efficiency of EE2 in d.magna. On the other hand, for the sediment dwelling midge c. riparius dietary uptake was low and depended on the nutritional quality of the sediment.