Achieving advanced nitrogen removal from low-carbon municipal wastewater using partial-nitrification/anammox and endogenous partial-denitrification/anammox

•Advanced nitrogen removal was achieved through PN/A-EPDA.•The effluent TN was 3.29 mg/L when the influent COD/TN ratio was 2.86.•This was achieved through the integration of four strategies.•Anammox bacteria coexist with AOB, NOB, DGAOs and DPAOs in the biofilm.•More anammox bacteria in the inner layer, more DGAOs and DPAOs in the outer layer.