Dimension effect of anammox granule: Potential vs performance.

Anammox granule is the key support of anammox sludge bed reactor. In this study, the anammox granules from a steady-state reactor were divided into 6 groups to investigate their dimension effects. The results of batch cultivation showed that the anammox granules with VMD (volume surface mean diameter) of 2.17 mm had the maximum SAA (specific anammox activity) of 399.6 ± 37.6 mg-N/(g-VSS·d). The bacterial community analysis demonstrated that Candidatus Kuenenia was the main detectable AnAOB genus in the anammox granules. Q-PCR together with flow cytometry indicated that the total number of viable AnAOB cells ascended with the increasing anammox granular size, suggesting the enhancement of nitrogen removal potential. On the contrary, the mass transfer efficiency descended with the increasing granular size, indicating the restriction of nitrogen removal performance. The maximum SAA was ascribed to the optimal match between nitrogen removal potential and mass transfer efficiency. The results of this study are helpful to comprehend the nitrogen removal capacity of anammox granules and to promote the optimization of anammox process.