Intensified partial nitrification and microbiome response in a membrane pulsing-aerated biofilm reactor

Membrane aerated biofilm reactor (MABR) has been developed as an energy-saving process for nitrogen removal in municipal sewage treatment, even in high ammonia wastewater. However, the impact of aeration pattern on biofilm microbiome assemblage and nitrification is not well understood. In this study, MABR and membrane pulsing-aerated biofilm reactor (MpABR) were established for partial nitrification under high ammonium loadings. The MABR and MpABR exhibited a 95 % nitrite accumulation rate (NAR), with over 60 % ammonium removal and nitrite conversion achieved after the start-up phase. The MABR and MpABR gradually adapted to the substantial increase in ammonium loading (350 mg NH4+-N<middle dot>L-1), resulting in stable and high NAR (96 %), ammonium removal efficiency (70 %), and nitrite conversion efficiency (67 %). Orthogonal experiments revealed that ammonium loading rate (ALR) was the primary factor regulating nitrite conversion and oxygen levels. A moderate ALR was preferable to achieve ideal partial nitrification and energy saving. Furthermore, the integrated MpABR-anaerobic ammonium oxidation (Anammox) maintained high total nitrogen (TN) removal (> 90 %) under high ALR conditions. Microbiome analysis revealed that nitrifiers (Nitrosomonas) and denitrifiers (Stenotrophomonas and Arenimonas) alternately dominated the biofilms at different stages. These findings highlight the potential for achieving efficient partial nitrification effects using a MpABR. The excellent TN removal performance of the MpABR-Anammox suggests its wide applicability in energy-efficient wastewater treatment.