The short- and long-term effects of Mn on biogranule-based anaerobic ammonium oxidation (anammox).

The short- and long-term effects of Mn on the performance of anaerobic ammonium oxidation (anammox) granules were investigated in the present study. Anammox activity was determined at various Mn concentrations in batch assays, and the 50% inhibition concentration value was determined to be 7.33mgL. However, no obvious deterioration of reactor performance was observed during the 150-day continuous-flow operation, and the nitrogen removal efficiency of the test reactor (R) fluctuated between 91% and 92% as the Mn concentration was increased from 1 to 200mgL. Additionally, the specific anammox activity, heme c content and the amounts of extracellular polymeric substances in the anammox biomass increased and then subsequently decreased. The results demonstrated that short-term exposure to Mn has a negative effect on anammox biomass, but the biomass could tolerate Mn stress after acclimation to a high concentration of 200mgL at the end of the continuous-flow experiment.