Roles of MnO on performance, sludge characteristics and microbial community in anammox system.

The long-term impacts of MnO on performance, sludge characteristics and microbial community of biogranule-based anaerobic ammonium oxidation (anammox) process were evaluated in an up-flow anaerobic sludge blanket reactor. It was found that the total nitrogen removal efficiency of reactor was fluctuated between 90%-93% at 1-200mgL MnO. Notably, the specific anammox activity was increased to maximum value of 657.3±10.6mgTNgVSSd at 50mgL MnO and then slightly decreased, but still higher than that achieved at 0-15mgL MnO, which had similar variation trends to the content of heme c and extracellular polymeric substances in anammox granules. High throughput sequencing indicated that MnO could improve the microbial richness and diversity of anammox granules and Candidatus Kuenenia was always the dominant species, and its abundance continued to increase to 21.3% at the end of operational experiment. Therefore, MnO could be applied to enhance the anammox process and the optimal influent MnO concentration was lower than 50mgL in view of the reactor performance and cost issues.