Please wait a minute...
Frontiers of Environmental Science & Engineering

ISSN 2095-2201

ISSN 2095-221X(Online)

CN 10-1013/X

Postal Subscription Code 80-973

2018 Impact Factor: 3.883

Front Envir Sci Eng Chin    2011, Vol. 5 Issue (4) : 633-638
Micro-analysis of nitrogen transport and conversion inside activated sludge flocs using microelectrodes
Lei WANG, Yongtao LV(), Xudong WANG, Yongzhe YANG, Xiaorong BAI
School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China
 Download: PDF(404 KB)   HTML
 Export: BibTeX | EndNote | Reference Manager | ProCite | RefWorks

To investigate the nitrogen transport and conversion inside activated sludge flocs, micro-profiles of O2, NH4+, NO2, NO3, and pH were measured under different operating conditions. The flocs were obtained from a laboratory-scale sequencing batch reactor. Nitrification, as observed from interfacial ammonium and nitrate fluxes, was higher at pH 8.5, than at pH 6.5 and 7.5. At pH 8.5, heterotrophic bacteria used less oxygen than nitrifying bacteria, whereas at lower pH heterotrophic activity dominated. When the ratio of C to N was decreased from 20 to 10, the ammonium uptake increased. When dissolved oxygen (DO) concentration in the bulk liquid was decreased from 4 to 2 mg·L-1, nitrification decreased, and only 25% of the DO influx into the flocs was used for nitrification. This study indicated that nitrifying bacteria became more competitive at a higher DO concentration, a higher pH value (approximately 8.5) and a lower C/N.

Keywords nitrogen transport      activated sludge flocs      heterotrophic bacteria      nitrifying bacteria      microelectrodes     
Corresponding Authors: LV Yongtao,   
Issue Date: 05 December 2011
 Cite this article:   
Lei WANG,Yongtao LV,Xudong WANG, et al. Micro-analysis of nitrogen transport and conversion inside activated sludge flocs using microelectrodes[J]. Front Envir Sci Eng Chin, 2011, 5(4): 633-638.
operating conditionsitemsinfluent conc./(mg·L-1)effluent conc./(mg·L-1)
DO /(mg·L-1)4COD130±118±8
Tab.1  Parameter settings and performance of the SBR
Fig.1  Micro-profiles inside activated sludge flocs at different pH values, (a) pH= 6.5; (b) pH= 7.5; (c) pH= 8.5
flux/(μmol·L-1·cm-2·h-1)pH= 6.5pH= 7.5pH= 8.5
ammonia flux0.011±0.0010.013±0.0010.032±0.003
nitrate flux-0.006±0.001-0.018±0.001-0.035±0.005
oxygen flux0.131±0.0010.115±0.0010.142±0.001
Tab.2  Fluxes inside activated sludge flocs at different pH values
Fig.2  Micro-profiles inside activated sludge flocs at different C/N, (a) C/N= 20; (b) C/N= 10
fluxes/(μmol·L-1·cm-2·h-1)C/N= 20C/N= 10
ammonia flux 0.019±0.0010.035±0.005
nitrate flux -0.025±0.001-0.026±0.002
oxygen flux 0.105±0.0060.160±0.002
Tab.3  Fluxes inside activated sludge flocs at different C/N
Fig.3  Micro-profiles inside activated sludge flocs at different DO concentrations, (a) 4 mg·L; (b) 2 mg·L
flux/(μmol·L-1·cm-2·h-1)DO= 4 mg·L-1DO= 2 mg·L-1
ammonia flux0.018±0.0010.011±0.001
nitrate flux -0.014±0.001-0.007±0.004
oxygen flux0.072±0.0020.054±0.002
Tab.4  Fluxes inside activated sludge flocs at different DO concentrations
1 Okabe S, Satoh H, Watanabe Y. In situ analysis of nitrifying biofilms as determined by in situ hybridization and the use of microelectrodes. Applied and Environmental Microbiology , 1999, 65(7): 3182–3191
2 Satoh H, Ono H, Rulin B, Kamo J, Okabe S, Fukushi K I. Macroscale and microscale analyses of nitrification and denitrification in biofilms attached on membrane aerated biofilm reactors. Water Research , 2004, 38(6): 1633–1641
doi: 10.1016/j.watres.2003.12.020 pmid:15016541
3 Satoh H, Sasaki Y, Nakamura Y, Okabe S, Suzuki T. Use of microelectrodes to investigate the effects of 2-chlorophenol on microbial activities in biofilms. Biotechnology and Bioengineering , 2005, 91(2): 133–138
doi: 10.1002/bit.20506 pmid:15892057
4 Chae K J, Rameshwar T, Jang A, Kim S H, Kim I S. Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes. Journal of Environmental Management , 2008, 88(4): 1426–1435
doi: 10.1016/j.jenvman.2007.07.016 pmid:17765389
5 Revsbech N P, Jorgensen B B. Microelectrodes: their use in microbial ecology. Advances in Microbial Ecology , 1986, 9: 293–352
6 Jensen K, Revsbech N P, Nielsen L P. Microscale distribution of nitrification activity in sediment determined with a shielded microsensor for nitrate. Applied and Environmental Microbiology , 1993, 59(10): 3287–3296
7 de Beer D, Glud A, Epping E, Kühl M. A fast-responding CO2 microelectrode for profiling sediments, microbial mats, and biofilms. Limnology and Oceanography , 1997a, 42(7): 1590–1600
doi: 10.4319/lo.1997.42.7.1590
8 Ploug H, Jorgensen B B. A net-jet flow system for mass transfer and microsensor studies of sinking aggregates. Marine Ecology Progress Series , 1999, 176: 279–290
doi: 10.3354/meps176279
9 Satoh H, Nakamura Y, Ono H, Okabe S. Effect of oxygen concentration on nitrification and denitrification in single activated sludge flocs. Biotechnology and Bioengineering , 2003, 83(5): 604–607
doi: 10.1002/bit.10717 pmid:12827702
10 Li B, Bishop P L. Micro-profiles of activated sludge floc determined using microelectrodes. Water Research , 2004, 38(5): 1248–1258
doi: 10.1016/j.watres.2003.11.019 pmid:14975658
11 de Beer D, van den Heuvel J C, Ottengraf S P P. Microelectrode measurements of the activity distribution in nitrifying bacterial aggregates. Applied and Environmental Microbiology , 1993, 59(2): 573–579
12 Schramm A, de Beer D, van den Heuvel J C, Ottengraf S, Amann R. Microscale distribution of populations and activities of Nitrosospira and Nitrospira spp. along a macroscale gradient in a nitrifying bioreactor: quantification by in situ hybridization and the use of microsensors. Applied and Environmental Microbiology , 1999a, 65(8): 3690–3696
13 Schramm A, De Beer D, Wagner M, Amann R. Identificationn and activities in situ of Nitrosospira and Nitrospira spp. as dominant population in a nitrifying fluidized bed reactor. Applied and Environmental Microbiology , 1999b, 64(9): 3480–3485
14 Satoh H, Okabe S, Norimatsu N, Watanabe Y. Significance of substrate C/N ratio on structure and activity of nitrifying biofilms determined by in situ hybridization and the use of microelectrodes. Water Science and Technology , 2000, 41(4-5): 317–321
15 APHA, AWWA, WEF . Standard Methods for the Examination of Water and Wastewater. 20th ed. Washington DC: American Public Health Association, 1999
16 Revsbech N P. An oxygen microelectrode with a guard cathode. Limnology and Oceanography , 1989, 34(2): 474–478
doi: 10.4319/lo.1989.34.2.0474
17 De Beer D, Schramm A, Santegoeds C M, Kühl M. A nitrite microsensor for profiling environmental biofilms. Applied and Environmental Microbiology , 1997b, 63(3): 973–977
18 Grady C P L Jr, Daigger G T, Lim H C. Biological Wastewater Treatment. 2nd ed. Boca Raton: CRC Press 1998
[1] Yongtao LV,Xuan CHEN,Lei WANG,Kai JU,Xiaoqiang CHEN,Rui MIAO,Xudong WANG. Microprofiles of activated sludge aggregates using microelectrodes in completely autotrophic nitrogen removal over nitrite (CANON) reactor[J]. Front. Environ. Sci. Eng., 2016, 10(2): 390-398.
[2] Yongji ZHANG, Lingling ZHOU, Guo ZENG, Huiping DENG, Guibai LI. Impact of total organic carbon and chlorine to ammonia ratio on nitrification in a bench-scale drinking water distribution system[J]. Front Envir Sci Eng Chin, 2010, 4(4): 430-437.
Full text