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Evaluations of biofilm thickness and dissolved oxygen on single stage anammox process in an up-flow biological aerated filter
- Liu, Tao, Quan, Xie, Li, Dong
- Biochemical engineering journal 2017 v.119 pp. 20-26
- Nitrosomonas, anaerobic ammonium oxidation, biodiversity, biofilm, biofilters, dissolved oxygen, nitrifying bacteria, nitrogen, species identification
- The overall influence of dissolved oxygen (DO) concentrations and biofilm thicknesses on single stage anammox process performance has been evaluated in this study. Results indicated the biofilm displayed a rapid initial increase and followed by a relatively slower formation rate during the operational period. The optimal DO concentration could be determined from a variety of biofilm thicknesses and as well the best biofilm thickness was required among different DO levels. In our lab-scale single stage anammox reactor with a constant hydraulic retention time of 1.0h and influent ammonium of 400mgL⁻¹, an optimal nitrogen removal capacity was acquired (TN removal loading of 2.18kg-Nm⁻³d⁻¹) at the DO level of 0.6mgL⁻¹ and biofilm thickness of 700μm. Species identification showed that Nitrosomonas related aerobic ammonium-oxidizing bacteria (AerAOB) and Candidatus Brocadia fulgida-like anaerobic ammonium-oxidizing bacteria (AnAOB) were the predominant functional bacteria mixed together with each other and exhibited no distinct niche. However, AerAOB exhibited higher biodiversity at the thinner biofilm while AnAOB showed a stable but lower biodiversity. Moreover, the population of AnAOB was smaller along with more scattered cells at the thinner biofilm while they trended to form specific irregular cauliflower-like zooglea as biofilm thickness increased.