Nutrients removal and nitrous oxide emission during simultaneous nitrification, denitrification, and phosphorus removal process: impact of temperature

Abstract

Simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) process was achieved in a SBR system operated in anaerobic–aerobic (low dissolved oxygen (DO)) mode. The contaminant removal and nitrous oxide (N₂O) emission characteristics in the reactor at two different temperatures (25 and 10°C) were investigated to evaluate the impacts of low temperature on SNDPR process. The results showed that TP and TN removal efficiencies of the reactor were 95.6 and 77%, respectively at 25°C indicating that simultaneous nitrogen and phosphorus removal were successfully achieved in the reactor. However, the removal of TN and ammonium was weakened significantly by the low temperature. The low temperature has little impact on phosphorus removal, mainly due to the enrichment of PAOs at low temperature. The N₂O emission mainly occurred during the low DO aerobic period. N₂O emission amount at 10°C was calculated as 648.8 μg N/g MLSS, which was about 43.3% higher than that at 25°C, and 10.11% of nitrogen removed was converted to N₂O at low temperature, showing that low temperature stimulated the emission of N₂O during SNDPR process.

Keywords:

• Nitrous oxide emission
• Nutrients removal
• SNDPR
• Temperature
• PHA

Acknowledgements

This work was supported by Natural Science Foundation of Jiangsu Normal University (No. 13XLR023), and Natural Science Foundation for Colleges of Jiangsu Province (No. 15KJB610005).