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Effects of Ethanol on Benzene Degradation Under Denitrifying Conditions


As a popular fuel oxygenate, ethanol frequently co-occurs with petroleum hydrocarbons, including benzene, in groundwater that is contaminated by gasoline. Anaerobic pathways have been identified in benzene biodegradation. Limited reports focus on denitrifying degradation of benzene; however, the role of ethanol in this pathway is unknown. This study investigated the effects of ethanol on benzene degradation under denitrifying condition by using groundwater and sediment samples collected from locations with known history of benzene contamination. Results indicate that benzene can be biodegraded under denitrifying conditions. When concentrations of nitrate were in the range of 480–920 mg/L, there is a critical value in ethanol concentration:Ethanol at concentration less than the critical value enhanced the denitrifying degradation of benzene over a period of time; in contrast, ethanol at concentration higher than the critical value, which was degraded before benzene, demonstrated an inhibitory effect. And the critical value varied with nitrate concentration. It appears that the role of ethanol may be closely associated with its own and nitrate concentrations. Two mathematical equations were established based on the data and may be used to determine if ethanol presents an enhancing or inhibitory effect on denitrification of benzene. The roles of ethanol in COD/NO3 –N and the subsequent denitrification of benzene were also studied. An optimal COD/NO3 –N ratio of 1.32 was obtained for this testing system, in which the highest rate of benzene degradation can be achieved under denitrifying conditions.

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  1. Baker KH, Herson DS (eds) (1994) Bioremediation. McGraw Hill, New York, pp 30–50

  2. Corseuil HX (1992) Enhanced degradation of monoaromatic hydrocarbons in sandy aquifer materials by microbial inoculation using biologically activated carbon. PhD thesis, The University of Michigan

  3. Corseuil HX, Hunt CS, Ferreira dos Santos RC, Alvarez PJJ (1998) The influence of the gasoline oxygenate ethanol on aerobic and anaerobic BTX biodegradation. Water Res 33(7):2065–2072. doi:10.1016/S0043-1354(97)00438-7

    Article  Google Scholar 

  4. Gineste P, Audic JM, Urbin V, Block J-C (1998) Estimate of nitrifying bacterial activities by measuring oxygen uptake in the presence of metabolic inhibitors allythioures and azide. Appl Environ Microbiol 64(6):2266–2268

    Google Scholar 

  5. Harrison I, Williams GM, Carlick CA (2003) Enantioselective biodegradation of mecoprop in aerobic and anaerobic microcosms. Chemosphere 53:539–549. doi:10.1016/S0045-6535(03)00456-9

    Article  CAS  Google Scholar 

  6. Hunt CS, dos Santos Ferreira R, Corseuil HX, Alvarez PJJ (1997) Effect of ethanol on aerobic BTX degradation. In: Leeson AL, Alleman BC (eds) In situ and on-site bioremediation, vol 4(1). Battelle Press, Columbus, p 49

    Google Scholar 

  7. Jirka A, Carter M (1975) Micro semi-automated analysis of surface and wastewaters for chemical oxygen demand. Anal Chem 47:1397–1402. doi:10.1021/ac60358a004

    Article  CAS  Google Scholar 

  8. Kao CM, Borden RC (1997) Site-specific variability in BTEX biodegradation under denitrifying conditions. Ground Water 35:305–311. doi:10.1111/j.1745-6584.1997.tb00087.x

    Article  CAS  Google Scholar 

  9. Laurino CN, Siñeriz F (1991) Denitrification by thermophilic soil bacteria with ethanol as substrate in a USB reactor. Biotechnol Lett 13(4):299–304. doi:10.1007/BF01041489

    Article  CAS  Google Scholar 

  10. Lovanh N (2004) The effect of ethanol on aerobic BTEX biodegradation. PhD thesis, University of Iowa

  11. Lovanh N, Hunt CS, Alvarez PJJ (2002) Effect of ethanol on BTEX biodegradation kinetics: aerobic continuous culture experiments. Water Res 36:3739–3746. doi:10.1016/S0043-1354(02)00090-8

    Article  CAS  Google Scholar 

  12. Lovley DR (1997) Potential for anaerobic bioremediation of BTEX in petroleum-contaminated aquifers. J Ind Microbiol Biotechnol 18:75–81. doi:10.1038/sj.jim.2900246

    Article  CAS  Google Scholar 

  13. Maier RM, Pepper IL, Gerba CP (2000) Environmental microbiology. Academic Press, San Diego

    Google Scholar 

  14. Powers SE, Hunt CS, Heermann SE, Corseuil HX (2001a) The transport and fate of ethanol and BTEX in ground-water contaminated by gasohol. Crit Rev Environ Sci Technol 31:79–123. doi:10.1080/20016491089181

    Article  CAS  Google Scholar 

  15. Powers SE, Rice D, Dooher B, Alvarez PJJ (2001b) Will ethanol blended gasoline affect groundwater quality? Using ethanol instead of MTBE as a gasoline oxygenate could be less harmful to the environment. Environ Sci Technol 35:24A–30A

    Article  CAS  Google Scholar 

  16. Ruiz-Aguilar GML, Fernandez-Sanchez JM, Kane SR (2002) Effect of ethanol and methyl-tert-butyl ether on monoaromatic hydrocarbon biodegradation: response variability for different aquifer materials under various electron-accepting conditions. Environ Toxicol Chem 21(12):2631–2639. doi:10.1897/1551-5028(2002)021<2631:EOEAMT>2.0.CO;2

    Article  CAS  Google Scholar 

  17. Ruiz-Aguilar GML, Alvarez PJJ (2005) Enhanced anaerobic biodegradation of BTEX-ethanol mixtures in aquifer columns amended with sulfate, chelated ferric iron or nitrate. Biodegradation 16(2):105–114. doi:10.1007/s10532-004-4897-5

    Article  CAS  Google Scholar 

  18. Samantha J, William A, Graham F (2000) Role of natural organic matter in accelerating bacterial biodegradation of sodium dodecyl sulfate in rivers. Environ Sci Technol 34(11):2240–2247

    Google Scholar 

  19. Si QY, Ran XQ, Zhou XD (2000) Regional pollution control of water and ecological conservation. China Press House of Environmental Science, Beijing, p 218 (in Chinese)

    Google Scholar 

  20. Tan K (1996) Soil sampling, preparation and analysis. Marcel Dekker Inc, New York

    Google Scholar 

  21. Tinsley J (1975) A manual of experiments for students of soil science. Aberdeen University, Aberdeen, pp 75–89

    Google Scholar 

  22. Wang X, Bartha R (1990) Effects of bioremediation on residues, activity and toxicity in soil contaminated by fuel spills. Soil Biol Biochem 22:501–505. doi:10.1016/0038-0717(90)90185-3

    Article  CAS  Google Scholar 

  23. Wang LJ, Wang JY (2004) Assessment and analysis of water quality in Weihe River in Baoji section. J Baoji Univ Arts Sci (Nat Sci) 24(4):304–306

    Google Scholar 

  24. Wu YG, Hui L, Li X, Yin DZ (2007) Degradation of aniline in Weihe Riverbed sediments under denitrification conditions. J Environ Sci Health A 42(3):413–419. doi:10.1080/10934520601187302

    Article  CAS  Google Scholar 

  25. Xue D, Quan X, Zhao Y, Yang F (1994) Sequential separation of sediment and adsorption of nitrobenzene. Environ Chem 13(2):107–112

    CAS  Google Scholar 

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This work was partially funded by the National Natural Science Foundation of China (No. 40472127), Program for New Century Excellent Talents in University (NCET-07-0694), and graduate starting seed fund of Northwestern Polytechnical University (200867).

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Correspondence to Yaoguo Wu.

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Wu, Y., Li, Y., Hui, L. et al. Effects of Ethanol on Benzene Degradation Under Denitrifying Conditions. Bull Environ Contam Toxicol 82, 145 (2009).

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  • Benzene
  • Biodegradation
  • Denitrification
  • Ethanol
  • Groundwater