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 N2O 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.