Environmental Science and Pollution Research

, Volume 24, Issue 30, pp 23714–23724 | Cite as

Effect of influent C/N ratio on N2O emissions from anaerobic/anoxic/oxic biological nitrogen removal processes

  • Xu Yan
  • Jiaxi Zheng
  • Yunping Han
  • Jianwei Liu
  • Jianhui Sun
Research Article


The problem of producing strong greenhouse gas of nitrous oxide (N2O) from biological nitrogen removal (BNR) process in wastewater treatment plants (WWTP) has elicited great concern from various sectors. In this study, three laboratory-scale wastewater treatment systems, with influent C/N ratios of 3.4, 5.4, and 7.5, were set up to study the effect of influent C/N ratio on N2O generation in anaerobic/anoxic/oxic (A2O) process. Results showed, with the increased influent C/N ratio, N2O generation from both nitrification and denitrification process was decreased, and the N2O-N conversion ratio of the process was obviously reduced from 2.23 to 0.05%. Nitrification rate in oxic section was reduced, while denitrification rate in anaerobic and anoxic section was elevated and the removal efficiency of COD, NH4 +-N, TN, and TP was enhanced in different extent. As the C/N ratio increased from 3.4 to 7.5, activities of three key denitrifying enzymes of nitrate reductase, nitrite reductase, and nitrous oxide reductase were increased. Moreover, microorganism analysis indicated that the relative abundance of ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were positively correlated with N2O generation, which was reduced from (8.42 ± 3.65) to (3.61 ± 1.66)% and (10.38 ± 4.12) to (4.67 ± 1.62)%, respectively. NosZ gene copy numbers of the A2O system were increased from (1.19 ± 0.49) × 107 to (2.84 ± 0.54) × 108 copies/g MLSS with the influent C/N ratio elevated from 3.4 to 7.5. Hence, appropriate influent C/N condition of A2O process could optimize the microbial community structure that simultaneously improve treatment efficiency and decrease the N2O generation.


Biological nitrogen removal Greenhouse gas Nitrous oxide C/N ratio Anaerobic/anoxic/oxic process NosZ gene 



This work was supported by the National Natural Science Foundation of China (NSFC China) (51408199) and the Key Science and Technology Program of Henan Province, People’s Republic of China (162102310096).


  1. Ahn JH, Kim S, Park H, Rahm B, Pagilla K, Chandran K (2010) N2O emissions from activated sludge processes, 2008-2009: results of a national monitoring survey in the United States. Environ Sci Technol 44:4505–4511CrossRefGoogle Scholar
  2. CEPB (2004) Standard methods for examination of water and wastewater (2002), 4th edn. Chinese Environmental Science Press, BeijingGoogle Scholar
  3. Chon K, Chang JS, Lee E, Lee J, Ryu J, Cho J (2011) Abundance of denitrifying genes coding for nitrate (narG), nitrite (nirS), and nitrous oxide (nosZ) reductases in estuarine versus wastewater effluent-fed constructed wetlands. Ecol Eng 37:64–69Google Scholar
  4. Chung YC, Chung MS (2000) BNP test to evaluate the influence of C/N ratio on N2O production in biological denitrification. Water Sci Technol 42:23–27Google Scholar
  5. Colliver BB, Stephenson T (2000) Production of nitrogen oxide and dinitrogen oxide by autotrophic nitrifiers. Biotechnol Adv 18:219–232CrossRefGoogle Scholar
  6. Czepiel P, Crill P, Harriss R (1995) Nitrous oxide emissions from municipal wastewater treatment. Environ Sci Technol 29:2352–2356CrossRefGoogle Scholar
  7. Foley J, de Haas D, Yuan ZG, Lant P (2010) Nitrous oxide generation in full-scale biological nutrient removal wastewater treatment plants. Water Res 44:831–844CrossRefGoogle Scholar
  8. Han Y, Liu J, Guo X, Li L (2012) Micro-environment characteristics and microbial communities in activated sludge flocs of different particle size. Bioresour Technol 124:252–258CrossRefGoogle Scholar
  9. Hanaki K, Hong Z, Matsuo T (1992) Production of nitrous oxide gas during denitrification of wastewater. Water Sci Technol 26:1027–1036Google Scholar
  10. He Q, Zhu YY, Fan LL, Ai HN, Huangfu XL, Chen M (2016) Effects of C/N ratio on nitrous oxide production from nitrification in a lab-scale biological aerated filter reactor. Water Sci Technol.
  11. Hu Z, Zhang J, Xie H, Liang S, Li S (2013) Minimization of nitrous oxide emission from anoxic-oxic biological nitrogen removal process: effect of influent COD/NH4 + ratio and feeding strategy. J Biosci Bioeng 115:272–278CrossRefGoogle Scholar
  12. Hynes, Knowles R (1984) Production of nitrous-oxide by Nitrosomonas europaea—effects of acetylene, pH, and oxygen. Can J Microbiol 30:1397–1404Google Scholar
  13. Itokawa H, Hanaki K, Matsuo T (2001) Nitrous oxide production in high-loading biological nitrogen removal process under low COD/N ratio condition. Water Res 35:657–664CrossRefGoogle Scholar
  14. Kampschreur MJ, van der Star WRL, Wielders HA, Mulder JW, Jetten MSM, van Loosdrecht MCM (2008) Dynamics of nitric oxide and nitrous oxide emission during full-scale reject water treatment. Water Res 42:812–826CrossRefGoogle Scholar
  15. Kampschreur MJ, Temmink H, Kleerebezem R, Jetten MSM, van Loosdrecht MCM (2009) Nitrous oxide emission during wastewater treatment. Water Res 43:4093–4103CrossRefGoogle Scholar
  16. Kimochi Y, Inamori Y, Mizuochi M, Xu KQ, Matsumura M (1998) Nitrogen removal and N2O emission in a full-scale domestic wastewater treatment plant with intermittent aeration. J Ferment Bioeng 86:202–206CrossRefGoogle Scholar
  17. Kishida N, Kim JH, Kimochi Y, Nishimura O, Sasaki H, Sudo R (2004) Effect of C/N ratio on nitrous oxide emission from swine wastewater treatment process. Water Sci Technol 49:359–365Google Scholar
  18. Kool DM, Wrage N, Zechmeister-Boltenstern S, Pfeffer M, Brus D, Oenema O, Van Groenigen JW (2010) Nitrifier denitrification can be a source of N2O from soil: a revised approach to the dual-isotope labelling method. Eur J Soil Sci 61:759–772CrossRefGoogle Scholar
  19. Kristjansson JK, Hollocher TC (1980) First practical assay for soluble nitrous oxide reductase of denitrifying bacteria and a partial kinetic characterization. J Biol Chem 255:704–707Google Scholar
  20. Lee DS, Jeon CO, Park JM (2011) Biological nitrogen removal with enhanced phosphate uptake in a sequencing batch reactor using single sludge system. Water Res 35:3968–3976CrossRefGoogle Scholar
  21. Li P, Wang Y, Zuo J, Wang R, Zhao J, Du Y (2017) Nitrogen removal and N2O accumulation during hydrogenotrophic denitrification: influence of environmental factors and microbial community characteristics. Environ Sci Technol 51:870–879CrossRefGoogle Scholar
  22. Lu HJ, Chandran K, Stensel D (2014) Microbial ecology of denitrification in biological wastewater treatment. Water Res 64:237–254CrossRefGoogle Scholar
  23. Lv Y, Ju K, Sun T, Wang L, Miao R, Liu T, Wang X (2016) Effect of the dissolved oxygen concentration on the N2O emission from an autotrophic partial nitritation reactor treating high-ammonium wastewater. Int Biodeter Biodegr 114:209–215CrossRefGoogle Scholar
  24. Mannina G, Cosenza A, Di Trapani D, Laudicina VA, Morici C, Odegaard H (2016) Nitrous oxide emissions in a membrane bioreactor treating saline wastewater contaminated by hydrocarbons. Bioresour Technol 219:289–297CrossRefGoogle Scholar
  25. Marques R, Rodriguez-Caballero A, Oehmen A, Pijuan M (2016) Assessment of online monitoring strategies for measuring N2O emissions from full-scale wastewater treatment systems. Water Res 99:171–179CrossRefGoogle Scholar
  26. Park KY, Inamori Y, Mizuochi M, Ahn KH (2000) Emission and control of nitrous oxide from a biological wastewater treatment system with intermittent aeration. J Biosci Bioeng 90:247–252CrossRefGoogle Scholar
  27. Ren YG, Wang JH, Xu L, Liu C, Zong RQ, Yu JL, Liang S (2015) Direct emissions of N2O, CO2, and CH4 from A/A/O bioreactor systems: impact of influent C/N ratio. Environ Sci Pollut R 22:8163–8173CrossRefGoogle Scholar
  28. Ribera-Guardia A, Marques R, Arangio C, Carvalheira M, Oehmen A, Pijuan M (2016) Distinctive denitrifying capabilities lead to differences in N2O production by denitrifying polyphosphate accumulating organisms and denitrifying glycogen accumulating organisms. Bioresour Technol 219:106–113CrossRefGoogle Scholar
  29. Rodriguez-Caballero A, Aymerich I, Marques R, Poch M, Pijuan M (2015) Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor. Water Res 2015(71):1–10CrossRefGoogle Scholar
  30. Sun FQ, Wu SW, Liu JJ, Li B, Chen YX, Wu WX (2012) Denitrification capacity of a landfilled refuse in response to the variations of COD/NO3 -N in the injected leachate. Bioresour Technol 103:109–115CrossRefGoogle Scholar
  31. Wang JH, Zhang J, Wang J, Qi PY, Ren YG, Hu Z (2011a) Nitrous oxide emissions from a typical northern Chinese municipal wastewater treatment plant. Desalin Water Treat 32:145–152CrossRefGoogle Scholar
  32. Wang YY, Geng JJ, Guo G, Wang C, Liu SH (2011b) N2O production in anaerobic/anoxic denitrifying phosphorus removal process: the effects of carbon sources shock. Chem Eng J 172:999–1007CrossRefGoogle Scholar
  33. Wang YY, Lin XM, Zhou D, Ye L, Han HC, Song CK (2016) Nitric oxide and nitrous oxide emissions from a full-scale activated sludge anaerobic/anoxic/oxic process. Chem Eng J 289:330–340CrossRefGoogle Scholar
  34. Wei D, Zhang K, Ngo HH, Guo W, Wang S, Li J, Han F, Du B, Wei Q (2017) Nitrogen removal via nitrite in a partial nitrification sequencing batch biofilm reactor treating high strength ammonia wastewater and its greenhouse gas emission. Bioresour Technol 230:49–55CrossRefGoogle Scholar
  35. Wunderlin P, Mohn J, Joss A, Emmenegger L, Siegrist H (2012) Mechanisms of N2O production in biological wastewater treatment under nitrifying and denitrifying conditions. Water Res 46:1027–1037CrossRefGoogle Scholar
  36. Xie T, Wang C (2011) Impact of different factors on greenhouse gas generation by wastewater treatment plants in China. Water Res Environ Protection 2:1448–1451Google Scholar
  37. Yan X, Li L, Liu J (2014) Characteristics of greenhouse gas emission in three full-scale wastewater treatment processes. J Environ Sci China 26:256–263CrossRefGoogle Scholar
  38. Yan X, Hang Y, Li Q, Sun J, Su X (2016) Impact of internal recycle ratio on nitrous oxide generation from an aerobic/anoxic/oxic biological nitrogen removal process. Biochem Eng J 106:11–18CrossRefGoogle Scholar
  39. Zhang QH, Yang WN, Ngo HH, Guo WS, Jin PK, Dzakpasu M, Yang SJ, Wang Q, Wang XC, Ao D (2016a) Current status of urban wastewater treatment plants in China. Environ Int 92-93:11–22CrossRefGoogle Scholar
  40. Zhang X, Wang X, Zhang J, Huang X, Wei D, Lan W, Hu Z (2016b) Reduction of nitrous oxide emissions from partial nitrification process by using innovative carbon source (mannitol). Bioresour Technol 218:789–795CrossRefGoogle Scholar
  41. Zhu XY, Chen YG (2011) Reduction of N2O and NO generation in anaerobic-aerobic (low dissolved oxygen) biological wastewater treatment process by using sludge alkaline fermentation liquid. Environ Sci Technol 45:2137–2143Google Scholar

Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • Xu Yan
    • 1
  • Jiaxi Zheng
    • 2
  • Yunping Han
    • 2
  • Jianwei Liu
    • 3
  • Jianhui Sun
    • 1
  1. 1.School of Environment, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution ControlHenan Normal UniversityXinxiangChina
  2. 2.Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijingChina
  3. 3.Beijing Engineering Research Center of Sustainable Urban Sewage System Construction and Risk ControlBeijing University of Civil Engineering and ArchitectureBeijingChina

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