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Preliminary Biodegradation Correlation for Bioventing

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					Preliminary Biodegradation
 Correlation for Bioventing

Maryam Jedari Eyvazi and Richard G. Zytner

          School of Engineering

             October 26, 2007
         INTRODUCTION
Soil contamination with total petroleum
hydrocarbons (TPH) is a problem




        http://apps.colliergov.net/pud/d/pollcntrl/images/TDI09.10.02B.JPG
   SOURCES of CONTAMINATION




             http://www.brinkenv.com/gsa/asmills.jpg




                                                       http://www.epa.gov/reg5rcra/wptdiv/r5lust/Leaking%20Tank.jpg
http://www.lawrenceroadfire.org/news%20stories%20html/images_news
       BIOREMEDIATON
Effective technique for cleaning petroleum
contaminated soil
    Natural attenuation
    Phytoremediation
    Landfarming
    Biopiles
    Bioaugmentation
    Bioventing
   BIOVENTING
             Nutrient and
Monitoring   Air Injection
  Wells                      Blower




                             Contaminated
                                 Soil
BIODEGRADATION KINETICS

       dC
     −    = k ⋅C
       dt

                               C
       ⎛C ⎞
     ln⎜ ⎟ = −k ⋅ t
       ⎜C ⎟
       ⎝ o⎠                        Time

C: TPH concentration
Co: initial concentration of TPH
t : time
k: degradation rate constant
   FACTORS AFFECTING
      BIOVENTING


Environmental condition       Controllable


Soil properties
                              Non-controllable
Contaminant characteristics
  BENEFITS OF A MODEL
Biodegradation kinetics are required for
prediction purposes

Field experiments are time consuming and
expensive

Biodegradation rate kinetics are not
transferable from one site to another
           OBJECTIVES
Identifying the factors affecting
biodegradation rate, including
  soil properties
  Contaminant concentration


Correlating these factors with biodegradation
rate constant
METHODOLOGY OVERVIEW
Simulate field conditions
Use a respirometer
Test variety of soils
Synthetic gasoline
Optimal environmental conditions
Develop a model
RESPIROMETER
                SOIL PROPERTIES

Soil Characteristics   Delhi   Elora   Brookston   Simcoe   Soil B



      % Sand           86.5     34        21        61.9    25.9

       % Silt           9       50       35.1       30.2    14.1

      %Clay             4.5    15.9      43.9       7.9      60

 %Organic Matter        1.2     3.1       1.5       1.5      2.1

  CEC (cmol/kg)        8.27    18.9      28.5       5.5     16.2
EXPERIMENTAL CONDITIONS

Contaminant type           Synthetic gasoline

Initial concentration   200-8000 (mg/kg dry soil)

Nitrogen source                  NH4Cl

C:N ratio                         10:1

Water content                   18% (wt)

Temperature                       25oC
   DEGRADATION OF TPH
Measured in three ways:

  TPH consumption (TPH extraction followed by gas
  chromatography (GC-FID))

  Oxygen consumption (measuring the pressure
  reduction in the system)

  CO2 production (trapped in KOH solution followed by
  titration by 0.1N HCl)
                                 RESULTS
k vs. TPH initial concentration

                   0.18

                   0.16

                   0.14

                   0.12
       k (1/day)




                    0.1

                   0.08

                   0.06

                   0.04

                   0.02


                          1000    2000   3000   4000   5000    6000   7000   8000
                                 Gasoilne initial concentration (mg/kg)
                                         RESULTS – cont.
k vs. soil type                                                                                  0.15



(clay, sand, and silt)                                                                            0.1




                                                                                   k (1/day)
                                                                                                 0.05



                                                                                                    0


               0.2
                                                                                                 -0.05


              0.15                                                                                       5   10   15   20        25          30    35   40
                                                                                                                            Clay (% )
  k (1/day)




               0.1

                                                                                                  0.2

              0.05

                                                                                                 0.15

                0                                                                    k (1/day)

                                                                                                  0.1

                     10   15   20   25   30      35       40   45   50   55   60
                                              Silt (% )
                                                                                                 0.05



                                                                                                    0




                                                                                                             30   40        50          60        70    80
                                                                                                                            Sand (% )
                    RESULTS – cont.
k vs soil organic matter

                  0.2


                 0.15

                  0.1
     k (1/day)




                 0.05

                    0


                 -0.05

                  -0.1

                         1.5              2            2.5        3
                               Soil Organic Matter Content (% )
                  RESULTS – cont.
k vs soil CEC
                   0.2



                  0.15



                   0.1
      k (1/day)




                  0.05



                     0



                  -0.05

                          10         15          20            25
                          Cation Exchange Capacity (cmol/kg)
                RESULTS – cont.
  Preliminary correlation using SYSTAT
ln(k ) = 0.794 ⋅ OM + 0.040 ⋅ Sand + 0.017 ⋅ Clay − 0.263 ⋅ ln(CEC ) − 5.891


                               r 2 = 0.87

   k: biodegradation rate constant (1/day)
   OM: organic matter content of soil (%)
   Sand: soil sand content (%)
   Clay: soil clay content (%)
   CEC: cation exchange capacity of soil (cmol/kg)
                                RESULTS – cont.
Predictions vs. measurements

                           -5    -4        -3       -2         -1   0
                                                                        0
 ln(k) predicted (1/day)




                                                                        -1


                                                                        -2


                                                                        -3


                                                                        -4


                                                                        -5
                                      ln(k) measured (1/day)
         FURHER WORK
Evaluate effect of other parameters
affecting the k value, including:
  soil microorganism population
  spill age


More experiments to improve the reliability
of the model
    ACKNOWLEDGMENT
NSERC Discovery Grant
Summer student April Yochim