Micropollutants in Urban Wastewater: A Review of Removal Performance and Best Available Techniques for Compliance with the Revised EU Urban Wastewater Treatment Directive

The presence of micropollutants in urban wastewater has emerged as a major environmental concern due to their persistence, biological activity, and potential adverse effects on aquatic ecosystems and human health. Conventional wastewater treatment plants (WWTPs) were primarily designed for the removal of organic matter and nutrients and are therefore often unable to achieve satisfactory removal efficiencies for many of these contaminants. In response to increasing scientific evidence and environmental concerns, the revised EU Urban Wastewater Treatment Directive (UWWTD) introduces new requirements for the monitoring and removal of selected micropollutants, promoting the implementation of advanced treatment technologies, particularly through quaternary treatment. This thesis presents a comprehensive literature review of the micropollutants addressed by the Directive (EU) 2024/3019, focusing on the removal performance of existing WWTPs. Published studies are critically analyzed to evaluate the effectiveness of conventional treatment processes in removing different classes of contaminants, mainly pharmaceuticals, PFAS and Microplastics. Particular attention is given to the variability in removal efficiencies, the influence of wastewater treatment configurations, and the physicochemical properties that govern contaminant fate during treatment. Furthermore, the thesis reviews the Best Available Techniques (BATs) and advanced treatment technologies that can be implemented to improve micropollutant removal. These include processes such as advanced oxidation processes and other emerging treatment solutions. Their removal performance, operational requirements, advantages, limitations, and applicability for upgrading existing WWTPs are discussed in relation to the objectives of the revised European regulatory framework. The outcomes of this review provide an overview of the current state of knowledge regarding micropollutant removal in wastewater treatment and identify the most promising technological options for achieving compliance with the revised UWWTD. The thesis also highlights existing knowledge gaps and future research needs, contributing to the understanding of the challenges and opportunities associated with the transition toward more sustainable and effective urban wastewater treatment systems.