1. No category

Why we need upscaling to describe
microbiological processes in groundwater:
Examples from fractured porous media and
bioaugmentation technologies
P.J. Binning
Two problems where upscaling is needed
Bioaugmentation
Enhanced biodegradation
in clays
Non detect
% Water supply wells with pesticides
Pesticide contamination of groundwater
100 %
0%
GEUS, 2006, 2009
Bioaugmentation
“the technique for improvement of the capacity of a
contaminated matrix (...) to remove pollution by the introduction
of specific competent strains or consortia of microorganisms”
Shimidzu et al. 2002
(El Fantroussi and Agathos, Curr. Opin. Microbiol. 2005)
Boldt et al. 2004
liquid microbial activated soil
culture
immobilized
microbes
microbes with
mobile genes
rhizosphere
biaogumentation
phyto-augmentation
Immobilized microbes
Simazine (mg kg-1)
• simazine, agricultural soil
• 50% water saturation
• 2-mm alginate beads
• Pseudomonas sp. MHP41
120
100
80
Data
60
Model
40
20
0
Morgante et al. (2010) FEMS Microbiol. Ecol. 71:114-126
0
5
10 15 20 25 30
Time (day)
Linuron
Herbicide used since 1965, now banned in 7 of 27 EU countries
Suspected developmental or reproductive toxin
First-order mineralization rate
C = C0 exp(− kt )
Variovorax sp. SRS16
k=0.216 day-1
80
60
40
20
14
CO2 (% of initial 14C)
100
0
0
96 192 288 384 480
Time (h)
Reaction time scales about 5 days
Diffusive transport
∂ (θ w + K H θ a )Cw
− ∇ • (θ w Dw + K H θ a Da )∇Cw + θ w kCw = 0
∂t
Expected diffusive time scales
17 days for 20mm bead separation
Mineralization time scale
10
105
Time (day)
20 years
1 year
90% removal, 2mm beads
6
104
saturation
100%
35%
10%
103
102
5
10
15
20
25
Bead spacing (mm)
30
A simple mixing model
mθ w,bVb
mθ w,sVs
dm
= − kb
− ks
= −keff m
dt
Vb + Vs
Vb + Vs
keff =
θ w,b kbVb + θ w,s k sVs
Vb + Vs
m = m0 exp(− keff t )
For Vb/(Vs+Vb)=1%
reaction rate reduced by a factor of 100
Vs
Vb
Simple mixing model
2mm beads, 100% saturation
100
-1
106
-2
105
keff (day-1)
10
keff
10
t90
10-3
104
10-4
103
10-5
102
10-6
101
Degradation rate for soil
100
10-7
0
20
40
60
80
Bead spacing (mm)
100
t90% (day)
Degradation rate in beads
Application of technology
Require ~24 tons 2mm beads for 1 ha to remove 90% linuron in 100 days
www.geograph.org.uk/photo/39325
(spaced at <10 mm in a layer of 100 mm)
Effect of water infiltration
∂ (θ w + K H θ a )Cw
∂C
− ∇ • (θ w Dw + K H θ a Da )∇Cw + qw w + θ w kCw = 0
∂t
∂z
Effect of water infiltration
Reduction in outlet concentration
1,0
C/C0
0,8
column
18.5 cm
Increasing column
length, decreasing
bead density
0,6
0,4
100%
Saturation
35%
100%
35%
10%
0,2
10%
0,0
5
10
15
20
25
Bead spacing (mm)
30
Effect of cell dispersal
experimental mineralization rate
(% of benzoate mineralized per day)
70
7%
27%
68%
60
50
full colonization
=bugs everywhere
40
30
20
10
minor colonization
=bugs in beads
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
mineralization rate predicted by the model
(% of benzoate mineralized per day)
Dechesne et al. (2010) Env. Sci. Technol. 44:2386-2392
Conclusions
Bioaugmentation has poorer performance in field
than expected from lab results
Models developed to predict field performance
• Simple Mixing Models: Can upscaling help here?
• Process models
Soil moisture, infiltration and other environmental
conditions affect performance
Cell dispersal may potentially improve the
technology (observed in sand, but limited in soil)
Enhanced biodegradation in clays
Clayey till
Sand aquifer
Chalk aquifer
•Long term secondary source of contamination!
•Remediation of chlorinated solvents?
•Stimulated Reductive Dechlorination, SRD?
DTU og Orbicon
Geological characterization
Geostatistical tools
Hydrogeological model
Modeling of
SRD in clay till
Optimization of enhancement
Spreading of reagents
Injection methods
Biogeochemical site characterization
Remediation design
Practical tools
Microbial and chemical
process understanding
What do clays look like?
Fracture mapping
Christiansen et al. (2008). ES&T, 42, 570–576.
Sand lenses
Fracture distribution – Field data
Cumulative fracture spacing
(average distance between vertical/sub-vertical fractures)
Depth m below ground surface (m)
0
0
0,5
1
2
1,5
2,5
0.5
1
1.5
2
2.5
1
3
3.5
4
4.5
5
5.5
2
6
6.5
7
7.5
8
8.5
3
3m
Location
Silstrup
Mammen
Højstrup 2
Højstrup
Gjorslev
Avedøre
Ranzausgade
Flakkebjerg
Havdrup
Vasby
Slæggerup
Haslev 2
Fårdrup
Estrup
Gedser
Grundfør
Lillebæk
Sigerslev 2
Ringe
Kamstrup
Tune
Sigerslev 1
Haslev 1
1
2
3
SprækkeJAGG, 2008
Klint, 2001, PhD Thesis
Anaerobic dechlorination
Various
microorganisms
Only
Dehalococcoides
species
Model system - simplification
Model developed in Comsol Multiphysics
ERD injection of donor and bacteria
fractures
Injection depths
Contaminant mass in matrix
Sum of chlorinated ethenes: TCE, DCE and VC
Mass in
matrix
Full scale application of enhanced reductive
dechlorination in clayey till (Sortebrovej, Denmark)
Anaerobic dechlorination associated with
sandstringers in clayey till
Clay core
Chlorinated ethenes [mg/kg]
0
1
2
3
4
5
6
Depth [m bgs.]
14,2
14,3
14,4
14,5
14,6
14,7
TCE
cis-DCE
VC
Ethen
7
8
Modeling - scenarios
Injection of donor in high
permeability conduits
Specific degraders only related
to sandstringers or fractures
Reaction zones surrrounding
sandstringers
1m
Base line – no dechlorination
RZ10 – 10 cm reaction zone
RZ30 – 30 cm reaction zone
RZ60 – 60 cm reaction zone
Best case – entire matrix
Generation of degradation
products – treatment area
Before remediation
RZ30
5 year after start of remediation
Comparison with field data
Degree of dechlorination 2 years after remediation
Mass of contaminants in treatment area
Start of remediation at day 0
Case study challenges:
How do we model geology?
How do we model hydraulics,
including injection of substrate?
Where are the bugs?
How do we model the
biogeochemistry?
Acknowledgements
Part 1
M. Owsianiak, A. Dechesne, B.F. Smets
Mikołaj Owsianiak, Arnaud Dechesne, Philip J. Binning, Julie C. Chambon, Sebastian R.
Sørensen, Barth F. Smets, Evaluation of Bioaugmentation with Entrapped Degrading Cells
as a Soil Remediation Technology, Environmental Science and Technology, 44, 19, 76227626, doi: 10.1021/es101160u, 2010.
Part 2
Julie Chambon, Gabriel Manoli, Philip Binning, Ida
Damgaard, Mette Broholm, Camilla Christiansen, Gitte
Lemming, Poul L. Bjerg
Julie C. Chambon, Mette M. Broholm, Philip J. Binning and Poul L. Bjerg, Modeling multicomponent transport and enhanced anaerobic dechlorination processes in a single fracture
– clay matrix system, Journal of Contaminant Hydrology,112, 1-4, 77-90, 2010.