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Cleaner water, new challenges: What does the revised Urban Wastewater Treatment Directive bring?

In September, our research group Mechanistic Environmental Toxicology, led by Prof. Luděk Bláha, attended the Biennial Conference VODA 2025 organized by the CzWA association in Litomyšl. This conference served as an important meeting point for experts – scientists, technologists, and regulators – focused on water management and protection. The central theme of this year’s conference was the newly revised Urban Wastewater Treatment Directive. 

18 Nov 2025 Event Science-policy interface

Presentation by Dr. Michal Bittner on the topic “Seasonal occurrence and environmental risk of pharmaceuticals in wastewater treated in semi-operational quaternary treatment units” (an article on the same topic is currently in the process of publication).

Researchers and technologists across Europe are now working on implementing the new requirements of Directive 2024/3019 of the European Parliament and Council (EU) of 27 November 2024 (Urban Wastewater Treatment Directive, UWWTP; hereinafter “the Directive”), particularly in terms of adapting treatment technologies to stricter limits. These changes aim to ensure higher quality of discharged water. More efficient monitoring methods are also being developed. Discussions cover not only technical solutions that will impact wastewater treatment plant operations and environmental protection but also legislative and economic implications of the revised Directive. 

New rules, new challenges: Where is urban water treatment heading? 

The original Urban Wastewater Treatment Directive (91/271/EEC) was adopted by the European Union in 1991 as a legal instrument to protect water quality, the environment, and human health. This Directive sets obligations for EU Member States regarding the collection, treatment, and monitoring of urban wastewater quality. 

These rules, addressing contamination of discharged water by viruses, bacteria, hazardous chemicals, or excessive nutrient loads, are regularly updated, and new provisions are introduced to respond to modern environmental challenges. Major changes in the cirrent Directive is the requirement for the removal of micropollutants – organic substances of human origin that occur in the environment at low concentrations but still impact ecosystems. The list of twelve indicator micropollutants, for which at least 80% removal must be ensured, includes active ingredients of medicines for pain, high blood pressure, and psychiatric disorders. 

Existing wastewater treatment technologies (WWTP) – from primary to tertiary treatment – are not specifically designed to remove organic micropollutants, and current WWTPs therefore do not meet the requirements of the new legislation. The revised Directive emphasizes the introduction of an additional quaternary treatment stage, which uses advanced methods for effective removal of micropollutants based on sorption, biodegradation, advanced oxidation processes, or membrane filtration. Implementing this additional (quaternary) stage represents a major technological and financial challenge. WWTPs will need to invest in entirely new technologies that are not currently in operation in the Czech Republic. Compliance currently applies to WWTPs with a capacity exceeding 150,000 population equivalents (PE), meaning the largest plants – in the Czech Republic, these are a handful of facilities serving regional capitals. The first plants must be upgraded by the end of 2033, and the remaining facilities by 2045. 

Who will pay for cleaner water? 

The Directive introduces a new system of Extended Producer Responsibility (EPR). Under this principle, those who are primarily responsible for the pollution – namely the pharmaceutical and cosmetics industries – should bear 80% of the financial costs for quaternary wastewater treatment and pollutant monitoring. Manufacturers of active substances that are rapidly biodegradable or produced in quantities below 1 tonne per year will be exempt. There are concerns that incurred costs will ultimately be passedon end consumers (or health insurance systems) through potential price increases for medicines (especially generics) and cosmetic products, or possibly through higher water and wastewater tariffs. 

Ongoing research into potential wastewater treatment technologies 

In connection with the Directive, active research is underway on quaternary water treatment technologies and micropollutant removal. Other research areas include digitalization for monitoring and plant management, and improving sustainability, efficiency, and energy neutrality of treatment processes. Newly introduced technologies must ensure reliable removal of a wide range of micropollutants, pathogenic organisms, antibiotic-resistant bacteria, hormonally active substances, and more. They must also be technically feasible and applicable under real-world conditions. It is essential to assess whether changing conditions (temperature, pH) affect process efficiency. Additional factors to consider before implementing new methods include energy consumption, operational and maintenance demands, carbon footprint, ecotoxicity of effluent, and more. 

Key Takeaways from VODA 2025 conferenceThis year’s VODA 2025 conference in Litomyšl featured numerous topics related to Directive implementation. Presentations covered research on various innovative wastewater treatment technologies and comparative studies evaluating the effectiveness of multiple established technologies for micropollutant removal. Advanced oxidation processes using ozone or UV radiation combined with granular activated carbon appear particularly promising. 

Our research group presented results of studies on new technologies for wastewater treatment and removal of organic micropollutants. Dr. Lucie Bláhová’s contribution focused on an innovative UV LED technology for wastewater treatment, which demonstrated excellent antibacterial efficiency and partially addressed the complexity of micropollutant removal. Dr. Michal Bittner presented a study comparing various quaternary treatment technologies (ultrafiltration, nanofiltration, granular activated carbon, UV and ozone, including combinations of these technologies). Seasonal variability in concentrations of selected micropollutants was monitored and the effectiveness of technologies in their removal during warmer and colder periods was evaluated . Doctoral student Nina Mokráčková’s poster illustrated the effectiveness of oxidation-reduction processes initiated by reactive iron forms in removing selected micropollutants. 

Why is the Directive an important and beneficial step? 

The revision of the Directive is not only aimed at improving water quality and purity but is also closely linked to Regulation (EU) 2020/741 on water reuse, which promotes safe and sustainable water recycling – for example, for agricultural irrigation. Reuse of treated wastewater is becoming increasingly important in the European context, as it helps reduce withdrawals from natural sources, increases regional water self-sufficiency, and strengthens agriculture’s resilience to climate variability. While southern and western Europe are moving forward in this area, water recycling for agricultural purposes is still not possible in the Czech Republic, as the European law has not yet been incorporated into national legislation. 

The Directive, with stricter requirements for wastewater treatment, is not just an unnecessary bureaucratic burden, as it is sometimes criticized. Rather, it represents an effort to address a scientifically grounded issue of organic pollution. Reducing concentrations of micropollutants in treated wastewater will help protect aquatic ecosystems and enable safe water reuse. 

References 

Diagram of the wastewater treatment process.
Poster by Nina Mokráčková on the topic “Evaluation of the effectiveness of reactive iron species in removing organic micropollutants from wastewater.”

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