This opinion paper reflects on the current challenges facing urban drainage systems (UDS) research, along with solutions for fostering sustainable development. Over the course of a year-long project involving 92 participants aged 24–38, including PhD candidates, post-doctoral researchers, and early-career academics, we identified critical challenges and opportunities for the sustainable development of UDS. Our exploration highlights four key challenges: limited public visibility leading to resource constraints, insufficient collaboration across subfields, issues with data scarcity and data sharing, and geographical specificities. We emphasise the importance of raising public and political awareness regarding UDS's vital role in climate adaptation and urban resilience, advocating for blue-green infrastructure and open data practices. Additionally, we address systemic academic barriers that hinder innovative research. We call for a shift away from metrics that prioritise quantity over quality. We recommend establishing stable career pathways that empower early-career researchers. This paper aims to catalyse a broader community dialogue about the future of UDS research, uniting voices from various career stages. By presenting actionable recommendations, we aim to inspire fundamental changes in research conduct, evaluation, and sustainability, ensuring the field of UDS is prepared to meet pressing urban water management challenges worldwide.

This research report addresses the current uncertainties regarding the technical service life and aging behavior of the most common sewer rehabilitation method, Cured-in-Place Pipe (CIPP) lining. The goal of this study is to develop a robust data foundation for a CIPP liner survival curve for use in aging models. The methodological approach includes (i) a literature review, (ii) interviews with sewer rehabilitation experts, and (iii) an analysis of data from Berliner Wasserbetriebe to create an updated and suitable data basis for the calibration of survival curves. The literature review and expert interviews predominantly estimate the service life of CIPP liners to exceed 50 years. However, the study also reveals that this lifespan is influenced by numerous factors and that there is a lack of reliable data. Further investigations of long-used CIPP liners are therefore essential. The installation process, particularly the curing phase, has been identified as the primary factor contributing to defects and deficiencies in CIPP liners. Standardizing damage assessment and condition evaluation for liner-specific defects, as well as establishing non-destructive inspection methods, is necessary to improve the understanding of aging behavior in the future. Recommendations include improving data collection during the operation, installation, and removal of CIPP liners, enhancing quality assurance during installation, investigating the impact of damage on service life, and promoting knowledge exchange among operators.

Addressing Europe's current challenges of aging sewer networks, the presented research focuses on the uncertainties in service life and aging behavior of the most used renovation technique, Cured in Place Pipe (CIPP) lining. Examining its aging behavior, common defects and deficiencies were analyzed through literature review and expert interviews. The findings influenced the proposition of a calibration setting for a deterioration model using survival curves. Identified defects stress the need for precise installation and curing processes. The study recommends a thorough review of the initially specified 50-year service life, acknowledging uncertainties during the installation process.

Extending the AI-driven Software SEMAplus with a risk prioritization module.

Selection and analysis of risk criteria as preliminary part of decision making.

Analysis of multicriteria decision approaches and choice of ELECTRE TRI.

Highlights

• The open source model ABIMO allows for a simple calculation of the urban water balance.

• The deviation from the annual natural water balance can be used to detect hotspots for WSUD.

• Transferability of ABIMO is currently tested between the German cities of Berlin and Cologne.

Die Simulationsergebnisse mit SIMBA# zeigten, dass mit den neu entwickelten ammoniumbasierten Regelungen und dem Air-Cycling-Konzept für MBR die Belüftung bzw. den Energieverbrauch deutlich reduziert werden konnte.An der Pilotanlage wurde demonstriert, dass mit den optimierten MSR-Konzepten stabile Ablaufwerte von CSB und Stickstoff erzielt werden können, welche mit großen Energieeinsparungen verbunden sind. Getestet wurden die ammoniumbasierten Regelungen und das Air-Cycling. Aber auch angepasste alternative MSR-Konzepte zur Optimierung der Schlammrezirkulation auf Basis der Nitratkonzentration im Ablauf und der Redoxpotential-basierten Regelung für die Belüftung der Nitrifikation wurden optimiert und getestet. Auch hier konnten sehr gute Ablaufergebnisse erzielt werden in Verbindung mit Energieeinsparungen. Allerdings wurde auch festgestellt, dass die verwendete ionenselektive Elektrode für die kontinuierliche Messung von Ammonium im Ablauf im niedrigen Messbereich (1-2 mg/L NH4-N) keine zuverlässigen Daten für eine Steuerung liefern kann.Im Rahmen des Projektes wurde auch ein neues Vorhersagemodell für Membranfouling entwickelt, um das Fouling 7 bis 14 Tage im Voraus zuverlässig vorherzusagen. Das Modell wurde dabei sowohl mit den historischen Betriebsdaten validiert und auch in der Praxis an der Pilotanlage getestet und bestätigt. Zusätzlich wurde ein Entscheidungsunterstützungs-system erarbeitet, welche die Fehlersuche und Wartung deutlich erleichtert.