EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Microbiological requirements for safe drinking water production at a large river impacted by human wastewater: a scenario analysis

Katalin Demeter1,2,10, Julia Derx10,3, Jürgen Komma3, Juraj Parajka3, Jack Schijven4,5, Regina Sommer10,6, Silvia Cervero-Aragó10,6, Gerhard Lindner10,6, Christa M. Zoufal-Hruza7, Rita Linke1,10, Domenico Savio10,8, Simone K. Ixenmaier1,10, Alexander K.T. Kirschner10,6, Harald Kromp9, Alfred P. Blaschke10,3, and Andreas H. Farnleitner1,10,8
Katalin Demeter et al.
  • 1TU Wien, Institute of Chemical, Environmental and Bioscience Engineering , Austria (
  • 2Center for Water Resource Systems E222, TU Wien, Vienna, Austria
  • 3Institute of Hydraulic Engineering and Water Resources Management E222/2, TU Wien, Vienna, Austria
  • 4Department of Statistics, Informatics and Modelling, National Institute for Public Health and the Environment (RIVM), Bilthoven,The Netherlands
  • 5Faculty of Geosciences, Department of Earth Sciences, Utrecht University, The Netherlands
  • 6Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
  • 7Division of Hygiene, Municipal Department 39, City Administration Vienna, Vienna, Austria
  • 8Division Water Quality and Health, Department of Pharmacology, Physiology, and Microbiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
  • 9Vienna Water, City Administration Vienna, Vienna, Austria
  • 10Interuniversity Cooperation Centre Water & Health (

Background: Rivers are important sources for drinking water supply, however, they are often impacted by wastewater discharges from wastewater treatment plants (WWTP) and combined sewer overflows (CSO). Reduction of the faecal pollution burden is possible through enhanced wastewater treatment or prevention of CSOs. Few methodological efforts have been made so far to investigate how these measures would affect the long-term treatment requirements for microbiologically safe drinking water supply under future changes.

Objectives: This study aimed to apply a new integrative approach to decipher the interplay between the effects of future changes and wastewater management measures on the required treatment of river water to produce safe drinking water. We investigated scenarios of climate change and population growth, in combination with different wastewater management scenarios (i.e., no upgrades and upgrades at WWTPs, CSOs, and both). To the best of our knowledge, this is the first study to investigate this interplay. We focussed on the viral index pathogens norovirus and enterovirus and made a cross-comparison with a bacterial and a protozoan reference pathogen (Campylobacter and Cryptosporidium).

Methods: We significantly extended QMRAcatch (v1.0 Python), a probabilistic-deterministic model that combines virus fate and transport modelling in the river with quantitative microbial risk assessment (QMRA). To investigate the impact of climatic changes, we used a conceptual semi-distributed hydrological model and regional climate model outputs to simulate river discharges for the period 2035 – 2049. We assumed that population growth leads to a corresponding increase in WWTP discharges. QMRAcatch was successfully calibrated and validated based on a four-year dataset of a human-associated genetic MST marker and enterovirus. The study site was the Danube in Vienna, Austria.

Results: In the reference scenario, approx. 98% of the enterovirus and norovirus loads at the study site (median: 1010 and 1013 N/d) originated from WWTP effluent, while the remainder was via CSO events. The required log reduction value (LRV) to produce safe drinking water was 6.3 and 8.4 log10 for enterovirus and norovirus. Future changes in population size, river flows and CSO events did not affect these treatment requirements, and neither did the prevention of CSOs. In contrast, in the scenario of enhanced wastewater treatment, which showed lower LRVs by 2.0 and 1.3 log10, climate-change-driven increases in CSO events had a considerable impact on the treatment requirements, as they affected the main pollution source. Preventing CSOs and installing enhanced treatment at the WWTPs together had the most significant positive effect with a reduction of LRVs by 3.9 and 3.8 log10 compared to the reference scenario.

Conclusions: The integrative modelling approach was successfully realised. The simultaneous consideration of source apportionment and concentrations of the reference pathogens were found crucial to understand the interplay among the effects of climate change, population growth and pollution control measures. The approach was demonstrated for a study site representing a large river impacted by WWTP and CSO discharges, but is applicable at other sites to support long term water safety planning.

How to cite: Demeter, K., Derx, J., Komma, J., Parajka, J., Schijven, J., Sommer, R., Cervero-Aragó, S., Lindner, G., Zoufal-Hruza, C. M., Linke, R., Savio, D., Ixenmaier, S. K., Kirschner, A. K. T., Kromp, H., Blaschke, A. P., and Farnleitner, A. H.: Microbiological requirements for safe drinking water production at a large river impacted by human wastewater: a scenario analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14863,, 2021.


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