Long term effect of MnO2 powder addition on nitrogen removal by anammox process

► Nitrogen removal performance of anammox process increased with MnO2 powder addition. ► The crude enzyme activity of anammox biomass with MnO2 powder addition increased 78.2%. ► The T-Mn content of anammox biomass with MnO2 powder increased 50-fold. ► The filament-like structure and larger particles in anammox cell of the reactor with MnO2 powder were observed.