Harnessing methane for improved nitrogen removal in membrane aerated biofilm reactors: towards sustainable wastewater...

This review examines the role of methane as an electron donor in Membrane Aerated Biofilm Reactor (MABR) systems, which conventionally use gas-permeable membranes to deliver oxygen directly to stratified biofilms for wastewater treatment. The integration of methane provides a sustainable carbon source for denitrification while also mitigating methane emissions. Methanotrophic denitrification enables methanotrophs to couple methane oxidation with nitrate or nitrite reduction, linking nitrogen removal with greenhouse gas mitigation. This dual function improves treatment efficiency, reduces energy use and operational costs, and addresses drawbacks of conventional MABRs, such as limited denitrification in low-carbon wastewater, by supplying a cost-effective carbon source. Methane-based MABRs, however, introduce challenges including methane-oxygen balance, microbial dynamics, and safety. Recent solutions include Layer-Structured Membranes (LSMs) and artificial intelligence-driven control, which improve biofilm stability, optimize gas transfer, and ensure long-term performance. Collectively, these advances underscore methane-based MABRs as a promising technology for sustainable and low-carbon wastewater treatment.