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

Abstract

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.