Biodegradation of MTBE and TBA by three distinct by rvk12222

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									Biodegradation of
MTBE and TBA
by three distinct anaerobic
microbial cultures



    Patricia G. Shin Na Wei and Dr. Kevin T. Finneran
   Department of Civil and Environmental Engineering
             University of Illinois at Urbana-Champaign
Outline

 Introduction

 Background & Objectives

 Material and Method

 Result & Discussion

 Conclusion
Introduction


     Methyl tert butyl ether (MTBE)
    Major fuel oxygenate compound
•     MTBE -> Highly water soluble                           MTBE

             (~50,000mg/l @ 25°C)
                         Plume migration
             -> Rarely adsorbed to solids
     Tert-butyl ether (TBA)
•    TBA    -> Metabolic by product of MTBE
•    Chemical structure resistant to microbial degradation
                                                     TBA
 Background

     Why anaerobic condition?


                                                       How can we remove the
                                                       contaminant in the aspect of
          Anaerobic
                                                       cost effectiveness?
          zone
                                                       -> In situ remediation
                                                       applicable in subsurface
                                                       environment

Distribution of dominant terminal electron accepting
processes (TEAPs) within the anaerobic source area
Objectives


  Mechanism of MTBE & TBA biodegradation
  in anaerobic condition to provide stronger
  strategy for encompassing diverse source area
   Investigate the effect of shifting
  biogeochemical condition in MTBE & TBA
  degradation
   Analyze the change of microbial community
  as electron acceptor shifts in the system
Research overview

  Sample collected from contaminated aquifer
  Find appropriate electron acceptor

    Mimic in situ conditions
 to assess MTBE/TBA                     Select and enrich
 biodegradation under                 anaerobic MTBE/TBA
 different redox conditions           degradations to investigate
 • 14C MTBE/TBA amended for           • Kinetics& pathway of anaerobic
 tracking mineralization percentage   MTBE/TBA biodegradation under
                                      different TEAPs
                                      • Factors affecting the degradation
                                      process
   Microbial community                • Biochemistry aspects: related
 study with various                   genes, proteins, etc
 biogeochemical conditions
 • via molecular biology tool
Culture development
Electron acceptor in each culture


  Anthraquinone-2,6-disulfonate [AQDS]
  Fe(III) reducing microorganism use this.

  Sulfate [SO42- ]
  Widely reported as a significant electron acceptor for in
  situ, anaerobic MTBE and TBA transformation.

  Fumarate [C4H2O42- ]
  Fumarate reduced to succinate. Key carbon compound
  in central metabolism. Relatively non toxic and soluble.
MTBE degrading cultures
                              3.5


                              3.0   MTBE
                                    TBA

                              2.5
         Concentration [mM]
                              2.0


                              1.5


                              1.0


                              0.5


                              0.0


                                    0      20   40          60   80   100   120

                                                     Days

                                                                              10% transfer
NW 1 – Liquid anaerobic culture with
       5 mM AQDS as terminal electron acceptor.
       Initial concentration of MTBE amended was 1mM.
MTBE degrading cultures
                              5
                                      MTBE
                              4       TBA


         Concentration (mM)   3


                              2


                              1


                              0



                                  0   20     40   60   80   100   120   140   160
                                                   Days
                                                                              10% transfer
NW 2 – Liquid anaerobic culture with
       10 mM sulfate as terminal electron acceptor.
       Initial concentration of MTBE amended was 1mM.
MTBE degrading cultures
                                     MTBE
                             6       TBA


        Concentration (mM)
                             4



                             2



                             0

                                 0    20    40   60     80   100   120   140
                                                 Days
                                                                         10% transfer
NW 3 – Liquid anaerobic culture with
       10 mM fumarate as terminal electron acceptor.
       Initial concentration of MTBE amended was 2mM.
Microcosm Study
Material and Method


•   Native sediment
        - Collected from petroleum-contaminated aquifer in California
•   Mineralization analysis
        - 14-C radiolabeled MTBE/TBA
        - GC-GPC (Gas chromatography – Gas proportional counting)
           14CO measured with Gas Chromatography equipped with
                2
            a Gas Proportional Counter
•   Sampling technique (aqueous MTBE/TBA analysis)
        - GC-FID
       (Gas chromatography – Flame ionization detector)
        - GC-MS
       (Gas chromatography – Mass spectrometry)
Microcosm study
                             16

                             14       MTBE
                                      TBA
                             12

          % Mineralization   10

                             8

                             6

                             4

                             2

                             0


                                  0    20    40   60      80    100   120   140   160   180

                                                       Time [Day]



Percent of mineralization of
[14C]-MTBE/TBA to 14CO2 in sulfate amended sediment
Microcosm study
                             8




                             6




          % Mineralization
                             4




                             2




                             0




                                 0   20     40    60      80    100   120   140   160   180

                                                       Time [Day]

                                 MTBE+500mM AC
                                 MTBE+500mM AC + H2 gas
                                 TBA+500mM AC
                                 TBA+500mM AC + H2 gas



Acetate amended as alternate carbon
                        Microcosm study
                                         MTBE                                        TBA


                   12                                        10

                             pH 5                                        pH 5
                             pH 6                                        pH 6
                   10        pH 7                                        pH 7
                                                              8
                             pH 8                                        pH 8
                             pH 9                                        pH 9
% Mineralization




                   8
                                                              6

                   6

                                                              4
                   4


                                                              2
                   2



                   0                                          0
                         0          50      100   150                0          50         100   150


                                                        Time [Day]



                    pH variation
Conclusion


  Anaerobic MTBE degradation is feasible
  when appropriate electron accepter is
  provided.
  Stable anaerobic MTBE degrading
  cultures are developed
  In these cultures, TBA builds up as MTBE
  degrades in stoichiometric level
Acknowledgements

 Dr. Kevin T. Finneran
 Finneran Lab Group
 British Petroleum (BP)
Thank you !
   Q&A
  Session

								
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