Evaluation of Bioassays and Wastewater Quality ... - Oekotoxzentrum

6. Main conclusions
From the results of the performance review (chapter 4) and the investigation of wastewater
quality (chapter 5) several main conclusions were drawn and approved by the international
expert group on ecotoxicology accompanying the pilot studies.
Main conclusions from the pilot studies in the project “Strategy Micropoll” are:
� Due to the advanced treatments in the pilot studies a broad range of micropollutants and
their effects were eliminated by more than 80%, as detectable in most in vitro bioassays and
with chemical analytics.
� There was no evidence for a toxicity increase due to a constant formation of stable toxic
ozonation by-products (i.e. by-products still present after sand filtration) in any test.
� Ozonation should be followed by a final filtration step with biological activity in order to
reduce the risk of potentially toxic, reactive transformation products being released in
waterbodies. The occurrence of such products and their potential to elicit effects was shown
in both pilot studies in selected in vivo bioassays (Lumbriculus reproduction assay in both
pilot studies, Fish Early Life Stage assay in Regensdorf).
� Overall, the quality of treated effluent was significantly improved, leading to improved
surface water quality.
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