Simultaneous nitrification and denitrification via nitrite in a pilot-scale modified anaerobic-anoxic-oxic reactor

Abstract

The performance of simultaneous nitrification and denitrification (SND) via nitrite including partial nitrification and SND was investigated in a pilot-scale-modified anaerobic–anoxic–oxic reactor. Since partial nitrification and SND need a similar requirement on dissolved oxygen (DO) level, a low DO was kept in the operation for achieving SND via nitrite. Results showed that SND via nitrite succeeded between 0.4 and 1.6 mg/L DO concentration. The average total nitrogen (TN) removal efficiency was 67.5%. Four forms of biodenitrification were quantified via the estimation of material balance and calculation of SND. SND via nitrite compared with the other three forms made 32.3% contribution to biodenitrification. The operation of a wastewater treatment plant was continuously studied as a comparison with the pilot reactor. With the same raw water, SND not only saved 82.6% of oxygen consumption as well as 30.4% of carbon source, but also owned a higher effluent quality on TN at 11.2 mg/L. Denaturing gradient gel electrophoresis results showed that after long-term hypoxia acclimation, the dominant denitrifier community changed and the abundance ratio of ammonia-oxidizing bacteria/nitrite-oxidizing bacteria was increased.

Keywords:

• Partial nitrification
• Simultaneous nitrification and denitrification via nitrite
• Denitrification pathway
• Dissolved oxygen
• Denaturing gradient gel electrophoresis

Acknowledgements

This research was financially supported by the Key Special Program for the Pollution Control (No. 2012ZX07101-003), the central university of Hohai University (No. 2013/B13020024) and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. We also wish to thank the staff of Lucun WWTP, for their support.