Hazardous Substances Challenging the Semi-Closed Water Cycle for Drinking Water Supply

Along the Danube River, there are multiple locations where water is abstracted for potable use, via riverbank filtration (RBF) systems. However, the chemical water quality of the Danube River is influenced by various discharges from wastewater treatment plants (WWTPs) and stormwater from an area with more than 80 million inhabitants throughout 14 countries. Important contributors to river pollution are the discharges from WWTPs, which introduce a range of persistent, mobile, and toxic (PMT) substances like PFAS into the water, some of which are hardly removed via the RBF systems. Therefore, there is a concern that ensuring future drinking water production through RBFs may not be guaranteed without costly additional treatment, particularly if drinking water standards become more stringent. Currently, the EU Urban Wastewater Treatment Directive is being updated. While the removal of pharmaceuticals is likely to be included, it is not clear for which other emerging PMT compounds, such as PFAS, this will be the case.

It is essential to consider not only treating PMT substances during drinking water production but also exploring upstream solutions. This includes examining emission points into the river such as WWTPs and industrial sources, and even further upstream. Specifically, the necessity of using certain chemicals should be assessed, including whether alternatives are available, and if these substitutes have better PMT characteristics. Another important consideration is the legacy contamination within the system. Legacy contamination can have lasting effects on PMT concentrations within the Danube, even if emissions from WWTPs and industries along the river are greatly reduced or eliminated. It remains unclear whether the impact of this legacy contamination on the river is significant compared to the load of PMT substances discharged into the river.

Providing Improved Knowledge to Secure the Safety of Drinking Water

One of the seven case studies within the EU-funded research project PROMISCES is focusing on the large-scale river catchment that runs from the mouth of the Danube Basin to Budapest, Hungary, including the bank filtration areas. The partners, the Institute for Water Quality and Resource Management at TU Wien, the Institute of Hydraulic Engineering and Water Resources Management at TU Wien, Deltares and the Budapest Waterworks Ltd. are collaboratively developing methods to:

-- Identify and quantify the origin of selected chemicals discharged into the Danube River

-- Assess the behavior or these chemicals during filtration in the riverbanks and during drinking water abstraction

-- Identify effective measures to control pollution levels in rivers and in drinking water impacted by rivers

Read more about the case study

It is within this context that we want to bring national, transboundary and international stakeholders together to gather various perspectives and identify needs for dealing with PMT substances within the Danube and the associated RBF systems.

The stakeholder workshop for the Danube River Basin has the following objectives:

• Discuss the above problem statement with local stakeholders to better frame the current situation
• Identify barriers and other factors that need to be addressed to ensure the safe and cost-effective use of Danube water for drinking water via RBF systems
• Co-create an interdisciplinary, system-wide strategy to create a toxic-free environment and protect water resources

Why should stakeholders participate?

• Play an active role in the development of a local water reclamation strategy
• Receive the latest developments from the research partners at TU Wien, Deltares and Budapest Waterworks
• Discuss current barriers and enablers related to PFAS contamination and RBF systems
• Network with other local and international stakeholders

Date & Time