Berlin Centre of Competence for Water

Deterioration models for sewer pipes often rely only on aggregated pipe-level data (pipe condition), without considering individual defects and their evolution. Is-it worth considering individual defects to improve deterioration models? A preliminary answer is to know if it is possible to model the evolution of individual defects. This study presents a methodology for analysing defect transitions in multi- inspected sewer pipes to gain insights into the aging and deterioration processes at the defect level. Using inspection data provided by Berliner Wasserbetriebe, covering 242,920 pipes and nearly 1.9 million observations, incl. defects encoded according to EN 13508-2, defect transitions were analysed across 24,734 inspection pairs. Defects between inspection pairs for each pipe and position are mapped, creating a transition matrix and knowledge graph to highlight defect inter-dependencies. The results reveal plausible transitions, such as gradual surface degradation from increased roughness to missing pipe wall parts, with varying durations, but also transitions that may reflect inspection uncertainties. Future work will incorporate defect severity classes and explore how these insights can enhance machine learning models through feature engineering or domain-informed approaches.

Abstract Nitrogen pollution represents one of the most significant threats to European freshwater ecosystems, with nitrite (NO 2 -N) standing out as a highly toxic compound for aquatic organisms, particularly vertebrates. Despite its recognized toxicity, little is known about its effects on invertebrates, even as riverine ecosystems experience profound species turnover. Here, we investigated the lethal and sublethal effects of nitrite on three representative amphipod species ( Gammarus fossarum , G. pulex , and G. roeselii ), which occupy distinct river sections and ecological niches. These species serve as models for assessing how nitrogen pollution may shape invertebrate communities across freshwater habitats. A series of laboratory bioassays revealed that G. fossarum , a species associated with upstream sections and pristine conditions, was the most sensitive to nitrite exposure, followed by the midstream species G. pulex and the long-established downstream species G. roeselii . To contextualize these findings, we compared the nitrite vulnerability of these amphipods with that of other freshwater invertebrates, offering a comprehensive perspective on how nitrogen pollution reshapes aquatic communities. While many invertebrate groups exhibit lower vulnerability to nitrite due to their reliance on hemocyanin—an oxygen-transport molecule mostly unaffected by nitrite oxidation—our results underscore significant interspecific differences in tolerance. For sensitive insect species, lethal effects occurred already at environmentally relevant concentrations, highlighting their exceptional vulnerability. In contrast, more tolerant groups such as amphipods survived higher concentrations, yet still displayed sublethal impairments, most notably a reduced leaf litter consumption—a key process in stream nutrient cycling—and altered behavioral responses at comparable exposure levels. Molluscs exhibit the highest tolerance, whereas insects are the most sensitive. Among crustaceans, tolerance varies widely, with a relationship to chloride content of the water mitigating the toxicity of nitrite. Chloride concentrations generally rise along the course of a river, placing upstream regions with naturally low chloride levels and their species at heightened risk. These differences highlight the potential role of nitrogen pollution as a driver of species turnover, particularly in multistressor environments. By linking species-specific sensitivity to broader ecological processes, like leaf litter consumption, this study provides critical insights into cascading effects of nitrogen pollution on freshwater biodiversity and ecosystem stability.

Chlorine dioxide (ClO2) is increasingly used as an alternative to chlorine in oxidative water treatment to mitigate the formation of halogenated disinfection byproducts. However, ClO2 can generate in situ free available chlorine (FAC) as a secondary oxidant, whose role in microbial inactivation remains poorly understood. This study investigates the impact of in situ-formed FAC during ClO2-based disinfection of Escherichia coli in the presence of natural organic matter (NOM). Bacterial inactivation was quantified using a novel approach based on lag phase extension in the growth curves. Exposure to 100 μM ClO2 extended the E. coli lag phase by approximately 40% relative to untreated controls. In contrast, the presence of 100 μM methionine, a selective FAC scavenger, markedly reduced disinfection efficacy, indicating that in situ FAC formation is a key driver of ClO2-based microbial inactivation. Additionally, disinfection efficiency decreased with increasing pH, consistent with FAC speciation (HOCl/OCl–; pKa = 7.54), as OCl– is less effective than HOCl. Moreover, pH-dependent speciation of NOM (phenol/phenolate; pKa ≈ 10) influences FAC reactivity, with phenolate exhibiting a higher scavenging capacity. These findings highlight the critical role of both FAC formation and NOM composition in determining the efficacy of ClO2-based disinfection.

ABSTRACT Climate change and industrialization necessitate a reassessment of water management strategies, particularly in agriculture, where reclaimed water supply often fails to meet irrigation needs. Storage can bridge supply gaps but raises concerns about water quality deterioration due to microbial changes and pathogen regrowth. This study examined microbial dynamics and regrowth during reclaimed water storage from a municipal wastewater treatment plant in Germany. The treatment train included ozonation, filtration and UV disinfection, and samples were analyzed using traditional culture methods for indicator organisms (e.g., Escherichia coli, Clostridium perfringens spores, and somatic coliphages) and 16S rRNA gene amplicon sequencing. Samples were collected throughout the treatment train and stored at 22 °C in the dark for up to 15 days. Results showed effective microbial reduction by treatment, with storage alone achieving similar declines in many cases. While treatment reduced bacterial diversity, storage gradually restored it, forming distinct microbial profiles from the original water quality. Bacterial communities converged during storage, suggesting a succession-like stabilization process. The findings highlight the dynamic nature of reclaimed water microbiomes and the importance of stimulating stable microbial communities to preserve water quality during storage. Advanced treatment should remove contaminants while supporting microbiomes that protect public health and the environment.

In the North German Basin, highly mineralised saline groundwaters are common below the Lower Oligocene Rupelian clay. The Rupelian Clay separates the Quaternary and Tertiary freshwater aquifer complex from the underlying saline aquifer complex and is of great importance for groundwater management. However, brackish groundwater influenced by deep saline water is found in the freshwater aquifer complex where the Rupelian Clay has been eroded. This is often the case above salt structures and along Pleistocene channels deeply cut into the underlying strata. As a result of this groundwater salinisation, various water utilities in the Berlin-Brandenburg region, including the Berlin water utility (Berliner Wasserbetriebe), were forced to reduce groundwater extraction volumes at certain locations or to abandon drinking water wells.This study analyses the spatial and temporal variations of environmental isotopes (δ¹⁸O, δ²H, 14C and δ13C) and hydrochemistry (Cl-, Br-, HCO3- and DOC) in combination with a 3D geological model of stratigraphic units in the freshwater aquifer complex focusing on a waterworks with elevated saltwater intrusion risk in Berlin (Germany). Issues on the genesis and temporal dynamics of geogenic groundwater salinisation were addressed in the study.A graphical method was employed to identify dominant geochemical processes and to produce a qualitative estimate of radiocarbon age using measured 14C and δ 13C and dissolved inorganic carbon (as hydrogen carbonate). The analyses indicate additional carbon input from ancient organic matter, which is more depleted in 13C than recent soil CO2. Radiocarbon dating revealed time scales of thousands to tens of thousands of years, depending on depth and geological conditions. The local meteoric water line (LMWL) and isotopic signatures (δ¹⁸O, δ²H) of hydrological half-years (winter/summer) were calculated using volume-weighted least squares from the local Global Network of Isotopes in Precipitation (GNIP) data station. The calculation of the hydrological half-year signatures proved to be particularly useful for the interpretation of regional flow and mixing processes. The half-year signatures allowed differentiation between samples influenced by bank filtrate and natural groundwater recharge. Stable isotopes in deep groundwater (>50 m below surface) samples showed light isotopic signatures indicating cold recharge conditions, e.g. during the Weichselian glacial period. Analysis of Cl/Br and DOC content revealed the geological units in which saltwater migration is dominant and where DOC dissolution occurs along the flow path. Together with isotopic measurements, literature research, numerical modelling and hydrochemical monitoring, an improved understanding of deep groundwater circulation and its implications for groundwater management in the freshwater aquifer complex has been developed. Although the spatial variability of elevated Cl concentrations due to saline upwelling in a well field is high, recommendations for the sustainable operation of saltwater-influenced well galleries were developed.

This article presents a practical case of a co-creation process within the framework of the European project Digital Water City (DWC). DWC sought to address the context and challenges of water in Europe with a participatory approach of co-creation as an integral part of Communities of Practice. To situate the concepts within their theoretical framework, the different approximations of co-creation and Communities of Practice (CoPs) are examined. The article analyzes the ways in which they have been used and applied in DWC as well as the ways in which the project has managed to articulate them at different levels. It discusses what has been done so far, whether the objectives related to co-creation have been achieved, what its added value to the project was, and the possible obstacles and successes. In order to gather this information, five case studies are presented and illustrated with a questionnaire that was carried out with the cities, researchers and key innovators. Results show that DWC´s co-creation process succeeded in incorporating end-users’ needs into the development of the digital solutions created, giving them a constructive role in the value-creation process, and bringing together different stakeholders from public and private sectors as well as researchers. It was also highlighted that the process and its format need to be adapted to each specific context and a culture of co-creation needs first to be established. The co-creation process and the DWC CoPs also raise governance questions and create new partnerships.

BackgroundWater bodies are affected by chemical contamination, including micropollutants, which is not fully captured by conventional chemical monitoring methods. The inclusion of integrative, effect-based in vivo and in vitro methods in standardized assessment procedures offers the possibility of bridging discrepancies between chemical and biological assessments and has already been proposed in several studies. However, there is a need to develop a comparable ecotoxicological assessment system for surface waters as for chemical and ecological status. This study aims to contribute to this discourse by investigating the temporal and spatial variation of ecotoxicological effects by assessing water grab samples of 15 different sites in central Germany over the course of 1 year using different in vitro assays.ResultsThe level of measured estrogenicity and anti-estrogenicity varied between the four measurement campaigns, while baseline toxicity, dioxin-like effects and mutagenicity showed relatively constant detectable effects over the study period. The impact of conventionally treated wastewater appeared to be one of the strongest influencing stressors, as direct comparisons of ecotoxicity upstream and downstream of wastewater treatment plant dischargers showed a significant increase for most of the conducted bioassays. Comparison of the measured estrogenicity with proposed threshold values showed effects within ecotoxicologically relevant ranges.ConclusionsBioassays record ecotoxicological effects on the basis of specific modes of action, allowing whole groups of substances to be identified as pollutants. Recording ecotoxicological status in this way is a useful complement to water assessment tools and can contribute to successful water management. Although most of the assays in this study were very consistent in detecting strong anthropogenic influences, possible temporal variations of individual assays should be taken into account when planning sampling strategies to improve the comparability of results.

Cryptic species are rarely considered in ecotoxicology, resulting in misleading outcomes when using a single morphospecies that encompasses multiple cryptic species. This oversight contributes to the lack of reproducibility in ecotoxicological experiments and promotes unreliable extrapolations. The important question of ecological differentiation and the sensitivity of cryptic species is rarely tackled, leaving a substantial knowledge gap regarding the vulnerability of individual cryptic species within species complexes. In times of agricultural intensification and the frequent use of pesticides, there is an urgent need for a better understanding of the vulnerability of species complexes and possible differences in adaptive processes. We used the cryptic species complex of the aquatic amphipod Gammarus roeselii, which comprises at least 13 genetic mtDNA lineages and spans from small-scale endemic lineages in Greece to a large-scale widely distributed lineage in central Europe. We exposed eleven populations belonging to four lineages to the neonicotinoid thiacloprid in an acute toxicity assay. We recorded various environmental variables in each habitat to assess the potential pre-exposure of the populations to contaminants. Our results showed that the populations differed up to 4-fold in their tolerances. The lineage identity had a rather minor influence, suggesting that the cryptic species complex G. roeselii does not differ significantly in tolerance to the neonicotinoid thiacloprid. However, the observed population differentiation implies that recent pre-exposure to thiacloprid (or similar substances) or general habitat contamination has triggered adaptive processes. Though, the extent to which these mechanisms are equally triggered in all lineages needs to be addressed in the future. Our study provides two key findings: Firstly, it shows that observed phylogenetic differences within the G. roeselii species complex did not reveal differences in thiacloprid tolerance. Second, it confirms that differentiation occurs at the population level, highlighting that susceptibility to toxicants is population-dependent. The population-specific differences were within the range of accepted intraspecific variability from a regulatory standpoint. From an evolutionary-ecological perspective, it remains intriguing to observe how persistent stresses will continue to influence tolerance and whether different populations are on distinct pathways of adaptation. Given that the potential selection process has only lasted a relatively short number of generations, it is crucial to monitor these populations in the future, as even brief exposure periods significantly impact evolutionary responses.

<p>This report describes the baseline conditions of each of the demo cases involved in NextGen before the start of the project and all pre-existing infrastructures and systems – prior to NextGen interventions across water, energy and material cycles. The baseline of the 10 sites (Altenrhein, Athens, Braunschweig, Bucharest, Costa Brava, Filton Airfield, Gotland, La Trappe, Spernal and Westland region) will be used to demonstrate the benefits and improvements achieved within the NextGen project, through the implementation of new CE solutions by the project, at each demo case.</p>