[Start-up and Process Characteristics of Simultaneous ANAMMOX and Denitrification (SAD) in a Pilot-scale Anaerobic Sequencing Batch Reactor (ASBR)]

A pilot scale anaerobic sequencing batch reactor (ASBR, working volume 530 L), inoculated by anaerobic sludge from an A²O process, was developed to investigate the start-up of anaerobic ammonia oxidation (ANAMMOX) and its combination with denitrification for deep-level nitrogen removal from saline wastewater. Simultaneously, the flora structure was analyzed. Results showed that under the conditions of temperature 35℃±1℃ and reaction time 14 h, ANAMMOX was successfully started-up after 160 days of operation. During the stabilized operation stage, ANAMMOX coupled with denitrification (SAD) led to a total nitrogen (TN) removal efficiency and removal rate of 91.1% and 0.45 kg·(m³·d)^-1, respectively. The successful cultivated sludge formed granules and presented as a light red color, with the main bacteria genus being Candidatus Brocadia (10.6%). Additionally, high efficiency nitrogen and organic carbon removal (COD and TN removal efficiency of 93.2% and 90.0%, respectively) from wastewater simulating desulfurization and denitrification tailings with high salinity (Cl^- concentration of 8000 mg·L^-1) was achieved in the SAD system by gradually increasing the salinity gradient. Moreover, the denitrification in SAD was mostly NO₃^--N→N₂, with partial denitrification (NO₃^--N→NO₂^--N) accounting for only 30.3%.