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| Candidatus Accumulibacter metabolic activity and population structure in MUCT process treating domestic wastewater with nitritation and denitrifying phosphorus removal |
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Abstract Nitritation and denitrifying phosphorus (P) removal was achieved in Modified University of Cape Town (MUCT) process treating domestic wastewater with a low C/N ratio. The effect of nitrite accumulation on performance of phosphorus removal and population structure of “Candidatus Accumulibacter” was investigated during nitritation establishment and destruction. Results indicated that P removal was mainly completed by denitrifying P removal of about 88%. The P removal efficiency had a clear correlation with the nitrite accumulation rate. Under nitritation, the P removal was 30% higher than that under complete nitrification, suggesting that nitrite was appropriate to be used as electron acceptor for denitrifying P removal when treating low C/N wastewater. Real time quantitative PCR assays were carried out using poly-P kinase 1 (ppk1) as phylogenetic marker to characterize the abundance of total Accumulibacter and the relative distributions and abundances of the Accumulibacter clades. Under complete nitrification, a very few Acc-I clade below 5% in total Accumulibacter was present using nitrate as electron acceptor. When the reactor transformed into nitritation, Acc-I clade gradually disappeared. The Acc-IID clade using nitrite as electron acceptor for denitrifying P removal was always the dominant Accumulibacter throughout the operational period, with above 92% on average in total Accumulibacter, even up to nearly 100%, which led to stable performance of denitrifying P removal using nitrite as electron acceptor. The nitrite concentrations significantly affected the abundances of Acc-IID clade.
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Received: 08 December 2012
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