Emerging contaminants in wastewater treatment: the effect of microplastics in an Integrated Fixed-film Activated Sludge (IFAS) Membrane BioReactor (MBR)

Microplastic (MP) pollution is increasingly recognized as one of the most urgent global environmental challenges. Despite the exponential growth in plastic production, only 9 % of plastic waste is currently recycled, contributing significantly to environmental pollution. Wastewater treatment technologies need to be evaluated for their effectiveness, also for emerging contaminants such as MP. This study features a pilot Integrated Fixed Film Activated Sludge (IFAS) reactor followed by two parallel lines: Line I, incorporating a membrane bioreactor (MBR), and Line II, consisting of secondary sedimentation and tertiary ultrafiltration. The main objectives were to assess the IFAS-MBR system's performance in terms of carbon and nutrient removal, greenhouse gas emissions and MP removal. The results demonstrated excellent removal efficiencies for carbon (97 % and 98 % in Line I and II, respectively), nitrogen (76 % and 82 % in Line I and II, respectively), and a comparable N 2 O emission factor (0.19 % of the influent total nitrogen in both lines). In terms of MPs, starting from an influent concentration of 10 mg L −1 polyethylene, effluent MPs concentrations were reduced to approximately 0.02 mg L −1 , achieving a 99.8 % removal rate in both lines. These findings highlight the potential of integrated IFAS-MBR systems in addressing multiple wastewater treatment targets, including emerging contaminants. • IFAS membrane systems were tested for microplastic removal from wastewater. • The membrane bioreactor and ultrafiltration retained more than 99 % of microplastics. • Carbon and nutrient removal exceeded regulatory targets (COD >97 %; TN >82 %). • The IFAS system achieved low nitrous oxide emissions, around 0.2 % of influent TN. • Membrane-based IFAS systems support sustainable wastewater treatment.