Pilot-scale evaluation of anammox-based mainstream nitrogen removal from municipal wastewater

Autotrophic nitrogen removal in the mainstream wastewater treatment process is suggested to be a prerequisite of energy autarkic wastewater treatment plants (WWTP). Whilst the application of anammox-related technologies in the side-stream is at present state of the art, the feasibility of this energy-efficient process at mainstream conditions is still under development. Lower operating temperature and ammonium concentration, together with required high nitrogen removal efficiency, represent the main challenges to face in order to reach this appealing new frontier of the wastewater treatment field. In this study, we report the evaluation of the process in a plug-flow granular sludge-based pilot-scale reactor (4 m3) continuously fed with the actual effluent of the A-stage of the WWTP of Dokhaven, Rotterdam. The one-stage partial nitritation–anammox system was operated for more than 10 months at 19 ± 1°C. Observed average N-removal and ammonium conversion rates were comparable or higher than those of convent...