In 2020, the European Union published ordinance EU 2020/741, establishing minimum requirements for water reuse in agriculture. The ordinance differentiates between several water quality classes. For the highest water quality class (Class A), the ordinance mandates analytical validation of the treatment performance of new water reuse treatment plants (WRTP) related to the removal of microbial indicators for viral, bacterial, and parasitic pathogens. While the ordinance clearly defines the numeric target values for the required log10-reduction values (LRV), it provides limited to no guidance on the necessary sample sizes and statistical evaluation approaches. The main requirement is that at least 90 % of the validation samples should meet the requirements. However, the interpretation of this 90 % validation target can significantly impact the required sample size, efforts necessary, and the risk of misclassifying WRTPs in practice. The present study compares different statistical evaluation approaches that might be considered applicable for LRV validation monitoring. Special emphasis is placed on the use of tolerance intervals, which combine percentile estimations with sample size-based uncertainty and confidence regions. Tolerance interval-based approaches are compared with alternative methods, including a) a binomial evaluation and b) the calculation of empirical percentiles. The latter are already used in existing European and U.S. regulations for bathing water and irrigation water quality. Our study demonstrates that using tolerance intervals allows for the reliable validation of WRTPs that achieve high LRVs relative to regulatory targets with comparatively smaller sample sizes compared to the other two approaches, while reducing the risk of misclassification. Additionally, we show that simplified approaches, such as a “9 out of 10” approach, pose a substantial risk of misclassification and should not be applied. We illustrate the behavior of these different approaches through simulation experiments and application to real data collected in 2022 and 2023 at a large WRTP in Germany.

The challenge of water reclamation using membranes in this study was the quite unique wastewater composition resulting from a high share of biotech wastewater. The high content of organic matter and high concentrations of calcium, bicarbonate, and sulphate were considered as challenging for membrane processes. Consequently, an innovative ultra-tight ultrafiltration (u-t UF) membrane was developed and tested on-site at pilot scale. In comparison, a conventional UF and an open nanofiltration (NF) were piloted. The aim was to find the best pre-treatment option for reverse osmosis (RO) to reduce fouling and scaling and produce fit-for-purpose water; for example, cooling. Overall, the quality of the currently used water source was surpassed by the pilot plant. Only a standard post-treatment of the RO permeate was necessary for stabilisation. Results indicated that denser membranes only minimally reduced fouling of RO. An assessment comparing the treatment trains in a life cycle assessment using the data collected from the pilot operation (UF/NF operating settings, RO plant performance, and the design of multi-stage industrial scale RO) revealed lower greenhouse gas emissions compared to seawater desalination. However, if the RO brine treatment becomes mandatory, the greenhouse gas emissions from water reclamation and supply will be higher than those from freshwater supply.

The use of activated sludge models (ASMs) is a common way in the field of wastewater engineering in terms of plant design, development, optimization, and testing of stand-alone treatment plants. The focus of this study was the development of a joint control system (JCS) for a municipal wastewater treatment plant (mWWTP) and an upstream industrial wastewater treatment plant (iWWTP) to create synergies for saving aeration energy. Therefore, an ASM3 + BioP model of the mWWTP was developed to test different scenarios and to find the best set-points for the novel JCS. A predictive equation for the total nitrogen load (TN) coming from the iWWTP was developed based on real-time data. The predictive TN equation together with an optimized aeration strategy, based on the modelling results, was implemented as JCS. First results of the implementation of the JCS in the real environment showed an increase in energy efficiency for TN removal.

Im EU-Projekt WaterMan drehen sich alle Aktivitäten um die Wasserwiederverwendung als ein neues Element des Wassermanagements. Erste Anwendungsbeispiele aus Schweden, Lettland, Litauen und Polen zeigen, wie Regenwasser hilft, Trinkwasserressourcen zu schonen.

Potenziale einer Substitution von Trinkwasser durch andere Wässer wurden für Frankfurt am Main in einer fachübergreifenden Studie mit Hilfe von Sekundärdaten und Szenariobetrachtungen abgeschätzt. Für das Stadtgebiet insgesamt sind sie erst langfristig und mit politischer Anstrengung umfassend realisierbar. Die Verwendung von Betriebswasser könnte ab 2050 nennenswert dazu beitragen, den Aufwand bei der Produktion von Trinkwasser zu reduzieren. Kosten- und CO2-Bilanzen verdeutlichen, dass der höhere Ressourcen- und Energieaufwand für Bau und Betrieb stark von örtlichen Voraussetzungen abhängt.

An innovative circular economy (CE) system was implemented at the wastewater treatment plant (WWTP) in Brunswick. The performance of the CE system was evaluated for 4 years: the thermal pressure hydrolysis enhanced the methane production by 18% and increased the digestate dewaterability by 14%. Refractory COD formed in thermal hydrolysis and increased the COD concentration in the WWTP effluent by 4 mg L−1 while still complying with the legal threshold. Struvite production reached high phosphorus recovery rates of >80% with a Mg:P molar ratio ≥0.8. Nitrogen was successfully recovered as ammonium sulfate with high recovery rates of 85–97%. The chemical analyses of secondary fertilizers showed a low pollutant content, posing low risks to soil and groundwater ecosystems. The total carbon footprint of the WWTP decreased due to enhanced biogas production, the recovery of renewable fertilizers and a further reduction of nitrous oxide emissions. Using green energy will be crucial to reach carbon neutrality for the entire WWTP.

Currently, there is uncertainty about emissions of pharmaceuticals into larger closed ecosystems that are at risk such as the Baltic Sea. There is an increasing need for selecting the right strategies on advanced wastewater treatment. This study analysed 35 pharmaceuticals and iodinated X-ray contrast media in effluents from 82 Wastewater Treatment Plants (WWTPs) across Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland and Sweden. Measured concentrations from Finland and Denmark were compared to predicted effluent concentrations using different levels of refinement. The concentrations predicted by the Total Residue Approach, as proposed by the European Medicines Agency, correlated with R(2) of 0.18 and 0.031 to measured ones for Denmark and Finland, respectively and the predicted data were significantly higher than the measured ones. These correlations improved substantially to R(2) of 0.72 and 0.74 after adjusting for estimated human excretion rates and further to R(2) = 0.91 and 0.78 with the inclusion of removal rates in WWTPs. Temporal analysis of compound variations in a closely monitored WWTP showed minimal fluctuation over days and weeks for most compounds but revealed weekly shifts in iodinated X-ray contrast media due to emergency-only operations at X-ray clinics during weekends and an abrupt seasonal change for gabapentin. The findings underscore the limitations of current predictive models and findings (...) demonstrate how these methodologies can be refined by incorporating human pharmaceutical excretion/metabolization as well as removal in wastewater treatment plants to more accurately forecast pharmaceutical levels in aquatic environments.

Die Partnerländer Schweden, Dänemark, Litauen, Lettland, Polen und Deutschland integrieren in WaterMan die Wasserwiederverwendung als ein neues Element des Wassermanagements, pilotieren Anwendungsbeispiele und bauen umfangreiche Kapazitäten auf lokaler Ebene auf.

Der Klimawandel stellt die Wasserwirtschaft vor immer größere Herausforderungen, insbesondere in West- und Südeuropa aufgrund lang anhaltender Dürren. Wie Abwasser im Sinne der Kreislaufwirtschaft als Ressource genutzt werden kann, zeigt ein Unternehmen aus Lleida.