It is widely acknowledged that the remaining
NO3− -N brought by the RAS changes the anaerobic
zone into an anoxic zone, which in turn damages the
anaerobic process of EBPR system [1-4]. Nitrate in the
anaerobic zone leads to the competition for available
carbon source between denitrifiers and PAOs and inhibits
the anaerobic phosphorus release severely, especially
when the system is under the “initial substrate limited” condition [5]. Peng et al. [6] showed that a
remaining NO3− -N content below 6 mg·L−1 was the
necessary condition to achieve 80% total phosphorus
(TP) removal efficiency.