Antibiotics in wastewater and removal efficiency of treatment plants: A systematic review

The environmental spreading of antibiotics, antibiotic-resistant bacteria, and antibiotic resistance genes, along with a plethora of other chemical compounds via wastewater systems, represents a critical interface between human activity and aquatic ecosystems. Wastewater treatment plants (WWTPs) have been identified by the latest EU directive 2024/3019 as points of primary control for limiting these emissions; however, conventional WWTPs, substantially designed for organic matter and nutrient removal, are often not able to remove such chemicals. As a result, treated effluents and sewage sludge may act as continuous sources of selective pressure for antimicrobial resistance in receiving environments. This systematic review critically evaluates the performance of advanced treatment technologies and monitoring strategies applied in wastewater systems for the removal of antibiotics and identifies research gaps while proposing recommendations for optimizing treatment processes and monitoring frameworks. Peer-reviewed studies published between January 2015 and March 2025 were retrieved from PubMed, Web of Science, and Scopus and screened following PRISMA 2020; 28 studies were included after eligibility assessment. Conventional biological treatment achieved only partial and variable antibiotic removal, with macrolides, fluoroquinolones, and sulfonamides frequently persisting in effluents at environmentally relevant levels. Advanced and quaternary treatments generally showed higher efficiencies, often >90%, though performance was compound- and process-dependent. The occurrence of transformation products and the presence of antibiotics in sewage sludge indicate additional exposure pathways, while heterogeneous monitoring approaches limited cross-study comparability. Overall, the evidence indicates that conventional WWTPs act as incomplete barriers to antibiotic release, supporting the need for optimized advanced treatment implementation, harmonized monitoring, and integrated management strategies.