Abstract:With the improvement of national and local sewage discharge standards, the upgrading andretrofitting of existing wastewater treatment systems become a major challenging task for wastewatertreatment plants (WWTPs). Specially, meeting the concentration limits for total nitrogen in the effluentis the important and difficult point. Thus, under the " carbon peaking and carbon neutrality" goal, thetechnological paths for improving the quality and efficiency of biological nitrogen removal (BNR) fromlow carbon to nitrogen domestic wastewater are elaborated in this review, and future study directionsare also suggested. Firstly, the traditional paradigms for enhancing BNR are systematically reviewed,primarily including deep excavation of the BNR potential of the original biological treatment process andincorporation with the denitrification biofilter advanced treatment process. Secondly, the research pro⁃gress and application prospect of low-carbon autotrophic BNR processes, such as anaerobic ammoniumoxidation, sulfur-driven autotrophic denitrification, and nitrate-dependent ferrous oxidation, are com⁃prehensively introduced, which can provide the theoretical basis and technical support for the establish⁃ment of environmentally friendly and efficient autotrophic BNR systems or synergistic heterotrophic-au⁃totrophic advanced BNR systems. Finally, future directions and trends of BNR from domestic wastewaterare proposed. The integration of biotechnology, material technology, and information technology can drivetechnological change and innovation in the wastewater BNR field. This review aims to provide guidancefor the synergistic effect of pollution and carbon reduction of BNR from domestic wastewater. Close-