Anaerobic membrane bioreactor and Anammox in municipal wastewater treatment: Mainstream versus side-stream, challenges, and prospects

Reducing the energy input and greenhouse gas emissions from the municipal wastewater (MWW) depends significantly on the application of innovative treatment technologies and processes. Anaerobic membrane bioreactor (AnMBR) and Anammox are emerging processes for MWW treatment, recognized for their energy efficiency and low carbon footprint. Extensive studies have demonstrated the feasibility of using independent AnMBR and Anammox systems for MWW treatment, and there is growing interest in integrating these two technologies into a complete treatment process. At this juncture, a comprehensive review from the perspective of the two technologies’ integration is needed to guide for the future practical applications of AnMBR-Anammox. Therefore, this review focuses on the state-of-the-art development of AnMBR-Anammox for MWW treatment, with particular attention to the application modes: mainstream mode (directly feeding MWW) and side-stream mode (feeding preconcentrated MWW). This review introduces the fundamentals and mechanisms underlying the integration of AnMBR and Anammox, summarizes the challenges and potential countermeasures, and proposes the strategy for selecting and combining AnMBR and Anammox to meet various requirements in different scenarios. Additionally, this work highlights that the expanded use of membranes for solid-liquid separation and the onsite utilization of waste sludge will facilitate an improved treatment performance and sustainability of AnMBR-Anammox plants. This review serves as a reference and guidance for the scientific community and industry in developing AnMBR-Anammox for MWW treatment, ultimately contributing to the achievement of net-zero emissions and sustainable development.