A new study presents the first Nordic-wide comparison of wastewater treatment systems under the revised EU Urban Wastewater Treatment Directive (UWWTD), providing key insights into the region’s readiness for expanded wastewater-based surveillance (WWS) and enhanced treatment requirements set for 2025. Researchers from the University of Helsinki, Finnish Institute for Health and Welfare (THL), NORCE (Norway), and Aalto University concluded that 85–90% of Nordic residents are connected to centralized wastewater treatment plants (WWTPs), offering a strong foundation for widescale wastewater-based monitoring of antimicrobial resistance (AMR), pathogens, and other emerging contaminants.
The study combined a Webropol survey of environmental authorities, wastewater experts, and policymakers with a systematic review of scientific and government literature. Responses were received from Finland, Sweden, Norway, Iceland, and the Faroe Islands, and were complemented by EU and national data. This work provides the first region-wide overview of community wastewater treatment coverage, processes, regulations, and challenges ahead of UWWTD implementation.
Despite high coverage, wastewater treatment levels vary significantly across the Nordic region. Secondary treatment is nearly universal in Finland and Sweden, while only about 4% of Icelandic plants apply it. Denmark, Finland, and Sweden enforce strict effluent standards to protect the sensitive Baltic Sea. In contrast, Norway and Iceland face unique geographical and climatic hurdles—mountainous terrain, sparse populations, cold climates, and reliance on marine discharges. These factors affect the feasibility of advanced treatment technologies such as nutrient removal, quaternary processes, and micropollutant reduction.
The recast EU UWWTD introduces new requirements: routine antimicrobial resistance (AMR) monitoring, expanded pollutant tracking, and enhanced nutrient removal. Nordic countries have strong infrastructure and regulatory frameworks, but challenges persist. Cold climates and permafrost complicate nitrogen removal. Remote terrain in Norway, Iceland, and Greenland limits centralized systems. Smaller municipalities struggle with financial and staffing constraints, while legacy coastal discharges demand costly upgrades.
“One-size-fits-all solutions will not work across the Nordic region, differences between densely populated Baltic coastal cities and remote Arctic communities are substantial. Tailored strategies and resilient systems are essential for equitable, sustainable sanitation”, says Dr. Ananda Tiwari, Postdoctoral researcher.
The work was conducted as a TRUSTME project funded by NordForsk:
Reference:
Tiwari, A., Valkama, K., Krolicka, A., Miettinen I.T., Pitkänen T. Coverage and treatment practices in Nordic wastewater treatment plants under the recast EU urban wastewater treatment directive. Discov Water 5, 105 (2025).