The pollution of water with chemicals is a global environmental problem that is addressed in different Sustainable Development Goals. Even though concrete environmental policy measures and guidelines to improve water quality have been in place at European and national levels for many years, there is still a high level of action needed.
Emission sources and pathways
Trace substances, which are also referred to microcontaminants or micropollutants, can have negative effects on aquatic ecosystems and on the production of drinking water even at very low concentrations. The accumulation of substances with low biodegradability, the formation of possible degradation products or the effects of the resulting complex mixture of substances in the environment are additional causes for concern. Trace substances originate from different sources and are discharged into the environment via a variety of emission pathways. Correspondingly, different starting-points and combinations of measures to reduce trace substances are conceivable and necessary. There should be a comprehensive strategy at national and/or, if required, regional level to address and push their implementation. In principle, technical and non-technical options are available for all emission sources, so that it is possible to begin implementing measures at the different starting-points.
Integrated measures are needed
Fraunhofer ISI has been working on both research-oriented and application-oriented projects in this field for many years. These include analyzing substance flows and modeling emissions to improve the identification and quantification of the discharged quantities and emission pathways as well as developing and evaluating mitigation strategies and individual measures. Comprehensive studies by Fraunhofer ISI for selected micropollutants have shown that source-based, application-based and end-of-pipe measures must be combined to achieve sufficient emission reductions.
This approach enables burden sharing and consideration of the polluter-pays and precautionary principle at the same time. The results formed the main foundation for the subsequent stakeholder dialogue on a national trace substance strategy launched by the German Federal Ministry for the Environment and the Federal Environment Agency in 2016, with the aim of developing comprehensive solutions involving all the relevant stakeholders. This process, which was organized and accompanied scientifically by Fraunhofer ISI, revealed, among other things, that new instruments involving the relevant stakeholders are needed when assessing the relevance of substances as well as when developing comprehensive emission reduction concepts. The results led, for example, to establishing the Trace Substances Centre at the Federal Environment Agency in 2021. Since then, a comparable dialogue process has been launched to implement the Trace Substance Strategy in the Hessian Ried (part of the Upper Rhine plain), also led by Fraunhofer ISI.