The effect of hydraulic retention time on ammonia and nitrate bio-removal over nitrite process.

Ammonia and Nitrate Bio-removal Over Nitrite (ANBON) is a new biological process, which couples denitratation with Anaerobic Ammonium Oxidation (ANAMMOX) to carry out simultaneous removal of nitrate nitrogen and ammonia nitrogen. The effect of hydraulic retention time (HRT) on the performance of ANBON process was investigated. The results showed that the optimal HRT was about 0.7 h and the nitrogen removal rate was 26.2 ± 0.7 g N·L-1·d-1, which was at top level reported in previous literatures. The change of HRT was found to trigger the change of microbial community in the reactor, which exerted a great effect on the performance of ANBON process. The community analysis based on 16S rRNA gene indicated that Halomonas and Candidatus Kuenenia were the dominant functional bacteria in the denitratation unit and the ANAMMOX unit respectively. These results are helpful for the development and application of ANBON process.