4. Conclusion
Nitritation and denitrifying P removal via nitrite pathway could be achieved by controlling DO concentration, hydraulic retention time and wastewater temperature. Real-time quantitative PCR method using ppk1 as a genetic marker could reveal the relevance of clade-level population dynamics of “Candidatus Accumulibacter” to the performance of EBPR. Clade IID using nitrite as an electron acceptor was always the dominant denitrifying P bacteria in the system, ensuring the stable performance of denitrifying P removal via nitrite pathway. Very few clade I (below 5%) using nitrate as electron acceptor were present in the reactor under complete nitrification, and then gradually disappeared during nitritation.