Integrating membrane aerated biofilm reactors with biological nitrogen removal processes: A new paradigm for achieving sustainable wastewater treatment plants

Membrane aerated biofilm reactors (MABRs) represent energy-efficient technology for biological nitrogen removal (BNR) that brings wastewater treatment plants (WWTPs) closer to carbon neutrality. In a MABR, gas-permeable hydrophobic membranes supply oxygen and serve as carriers for biofilm attachment. Given the importance of sustainable nitrogen removal from wastewater, MABR technology has attracted significant attention in recent years, leading to advances in theoretical understanding and practical applications, particularly in coupling with novel BNR processes (e.g., simultaneous nitrification/denitrification [SND] and partial nitritation/anaerobic ammonium oxidation [PN/A]). This review summarizes the intrinsic characteristics of MABRs (e.g., bubbleless aeration, counter diffusion) and their technical advantages (e.g., energy efficiency, low greenhouse gas and volatile organic compound emissions, compatibility with novel BNR processes). We also describe the robust SND performance of MABRs and the implications for upgrading existing WWTPs. Additionally, we systematically present the technological breakthroughs in the integration of the PN/A process into MABRs. Finally, we provide insights into the applicability of novel BNR-based MABRs in efficient WWTP construction and discuss future research directions of MABR technology based on the interdisciplinary integration of materials science, information technology, and biotechnology. This review contributes to a deeper understanding of MABR applications in wastewater nitrogen removal and provides guidance for further developments of this cost-efficient technology to achieve sustainable energy performance in future WWTPs.