Nitrogen and phosphorus budgets were compiled for the littoral (29 km2) and pelagic (329 km2) of ancient, deep, clear, and hard water Lake Ohrid (Albania and North Macedonia), to assess the importance of the littoral in nutrient retention. P originates mainly from domestic point sources (73%), for N this is karst seepage (50%). Total littoral loads are estimated at 1700 kg P and 23,200 kg N km-2 (area of littoral) yr-1; net littoral retention is 31% ± 13% for P and 40% ± 16% for N, largely in the dense charophyte belt. P retention is mainly due to detritus burial, but also due to coprecipitation; N retention is due to both detritus burial and denitrification. A Monte Carlo plausibility analysis balanced the budget by increasing nonconnected domestic household inputs (from 20% to 27% of external load), and decreasing pelagic sediment P burial by 27% and littoral denitrification by 25%. Scenario projections for 2100 corresponding to SRES A2 and B1 were linked to an AQUASIM lake ecosystem model. Under B1, the changes were small compared to the present. A2, however, led to a major reduction in precipitation, an increase in evapotranspiration, a reduction in river outflow (to ~20%), a doubling in P-loading, a drop in lake level of ~1.5 m, and a decline in the extent of the charophyte belt. Areal loading of the littoral would increase accordingly, but water transparency would not decline much. Also, the littoral vegetation will witness a shift in species composition, and an increase in filamentous Cladophora cover.

Combined sewer overflows (CSOs) are of major environmental concern for impacted surface waterbodies. In the last decades, major storm events have become increasingly regular in some areas, and meteorological scenarios predict a further rise in their frequency. Consequently, control and treatment of CSOs with respect to best practice examples, innovative treatment solutions, and management of sewer systems are an inevitable necessity. As a result, the number of publications concerning quality, quantity, and type of treatments has recently increased. This review therefore aims to provide a critical overview on the effects, control, and treatment of CSOs in terms of impact on the environment and public health, strict measures addressed by regulations, and the various treatment alternatives including natural and compact treatments. Drawing together the previous studies, an innovative treatment and control guideline are also proposed for the better management practices.

Die energetischen Potenziale in kommunalen Kläranlagen werden nur unzureichend ausgeschöpft und bleiben in Klimaschutzmaßnahmen häufig unberücksichtigt. Kläranlagen gehören jedoch zu den größten kommunalen Stromverbrauchern und haben dadurch einen signifikanten CO2-Fußabdruck. Im Vorhaben REEF 2W, das von der EU im Rahmen des Programms INTERREG 2 gefördert wird, wird mit Blick auf öffentliche Infrastrukturen von Städten und Gemeinden ein Entscheidungstool zur strategischen Planung entwickelt. In diesem Tool können neue Technologien in die bestehende Anlagensituation integriert werden, um eine höhere Energieeffizienz und eine Verbesserung der Nutzung von nachwachsenden Rohstoffen zu erzielen. Dies soll durch Kombination und Integration der Sektoren Abfall- und Abwasserbehandlung erreicht werden. Das Projekt untersucht im Rahmen der Toolentwicklung die Ressourcenströme und notwendigen technischen Infrastrukturen. Ein Kernstück bildet dabei die Co-Fermentation von Klärschlamm und Bioabfall während deFaulungsprozesses, wodurch sich die Wärme- und Energieerträge (Strom oder Gas) beträchtlich steigern lassen können. Daneben werden neue Wege zur Nutzung des anfallenden Faulgases aufgezeigt, z. B. Gasaufbereitung und Einspeisung ins Gasnetz sowie Power-to-Gas Technologie. Ziel des Excel-basierten Entscheidungstools ist es letztlich, verschiedene innovative Technologiekombinationen energetisch, wirtschaftlich und ökologisch mit dem aktuellen Status zu vergleichen.

Cities worldwide are facing several challenges connected to urbanization and climate change. Several cities have identified the implementation of nature-based solutions (NBS) as an option to mitigate several challenges at once. However, can two different aims be reached with NBS in the same location? This question has not yet been addressed. This paper discusses the spatial compatibility of NBS implementation strategies to tackle (1) urban heat island (UHI) effects and (2) water pollution at the same location. The evaluation is based on a spatial analysis of Berlin. We found a positive correlation of high UHI and median high stormwater pollution loads for zinc, total suspended solids, Polycyclic Aromatic Hydrocarbons and Terbutryn. Out of more than 14,000 building/street sections analyzed, 2270 showed spatial matching of high UHI and high stormwater pollution loads. In the majority of building/street sections, stormwater pollution was high for three out of the four parameters. We conclude that the compatibility of NBS implementation for both challenges depends both on the implementation strategies for NBS and on the specific NBS measures. Our spatial analysis can be used for further planning processes for NBS implementation.

Wie können unsere Kommunen die Möglichkeiten, die Regenwasserbewirtschaftung und neuartige Wasserinfrastrukturen als auch blau-grüne Infrastrukturen bieten, gut in ihre Planungsprozesse integrieren? Wie können die Leistungen der einzelnen Maßnahmen schnell, einfach und gut im Rahmen von Planungsworkshops mit Fachakteuren und Laien kommuniziert und genutzt werden? Hierzu wurden im Forschungsprojekt netWORKS 4 sogenannte Infokarten zu 20 Infrastrukturbausteinen als partizipatives Planungstool entwickelt und in verschiedenen Workshops erprobt. Sie sind nun als frei verfügbares Tool kostenlos zugänglich.

Probabilistic quantitative microbial risk assessment (QMRA) studies define model inputs as random variables and use Monte-Carlo simulation to generate distributions of potential risk outcomes. If local information on important QMRA model inputs is missing, it is widely accepted to justify assumptions about these model inputs by using external literature information. A question, which remains unexplored, is the extent to which previously published external information should influence local estimates in cases of nonexistent, scarce, and moderate local data. This question can be addressed by employing Bayesian hierarchical modeling (BHM). Thus, we study the effects and potential benefits of BHM on risk and performance target calculations at three wastewater treatment plants (WWTP) in comparison to alternative statistical modeling approaches (separate modeling, no-pooling, complete pooling). The treated wastewater from the WWTPs is used for restricted irrigation, potable reuse, or influences recreational waters, respectively. We quantify the extent to which external data affects local risk estimations in each case depending on the statistical modeling approach applied. Modeling approaches are compared by calculating the pointwise expected log-predictive density for each model. As reference pathogens and example data, we use locally collected Norovirus genogroup II data with varying sample sizes (n = 4, n = 7, n = 27), and complement local information with external information from 44 other WWTPs (n = 307). Results indicate that BHM shows the highest predictive accuracy and improves estimates by reducing parameter uncertainty when data are scarce. In such situations, it may affect risk and performance target calculations by orders of magnitude in comparison to using local data alone. Furthermore, it allows making generalizable inferences about new WWTPs, while providing the necessary flexibility to adjust for different levels of information contained in the local data. Applying this flexible technique more widely may contribute to improving methods and the evidence base for decision-making in future QMRA studies.

Sustainable urban drainage systems (SUDS) can significantly reduce runoff from urban areas. However, their potential to mitigate acute river impacts of combined sewer overflows (CSO) is largely unknown. To close this gap, a novel coupled model approach was deployed that simulates the effect of realistic SUDS strategies, developed for an established city quarter, on acute oxygen depressions in the receiving river. Results show that for an average rainfall year the SUDS strategies reduce total runoff by 28% - 39% and peak runoff by 31% - 48%. Resulting relative reduction in total CSO volume ranges from 45% - 58%, exceeding annual runoff reduction from SUDS by a factor of 1.5. Negative impacts in the form of fish-critical dissolved oxygen (DO) conditions in the receiving river (<2 mg DO/L) can be completely prevented with the SUDS strategies for an average rainfall year. The realistic SUDS strategies were compared with a simpler simulation approach which consists in globally downscaling runoff from all impervious areas. It indicates that such a simple approach does not completely account for the positive effect of SUDS, underestimating CSO volumes for specific rain events by up to 13%. Accordingly, global downscaling is only recommended for preliminary planning purposes.