Characteristics and Mechanism of Nitrite Accumulation in the Denitrification and Phosphorus Removal Process
Sequencing batch reactor(SBR)was constructed in this study.Anaerobic/aerobic and anaerobic/anoxic/short aerobic operation mode was used to enrich denitrifying glycogen-accumulating organisms,DGAOs)and denitrifying phosphorus-accumulating bacteria(DPAOs)to compare the difference in the efficiency of NO2--N accumulation with influent TP concentration of 0.43 mg/L and 4.72 mg/L,respectively.The changes of microbial community structure and key nitrogen removal genes were analyzed to explore the accumulation mechanism of NO2--N under low influent phosphorus concentration.The results shows that the NO3-N removal efficiency exceeded 95%at both low and high influent phosphorus concentrations,but the average accumulation rate of NO2--N reached 62.15%at low influent phosphorus concentrations,and NO2--N accumulation was basically absent at high influent phosphorus concentrations.The microbial community structure analysis showed that the abundance of DGAOs at low influent phosphorus concentration was significantly higher than that at high influent phosphorus concentration.The abundance of DPAOs was close to that of DPAOs under both conditions.The abundance of genes related to nitrogen removal showed that the abundance of genes related to nitrogen removal in this study had no direct effect on NO2--N accumulation.
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