Electrokinetic enhanced bioremediation of organic 

contaminants in groundwatercontaminants in groundwater

Ri h d GillRichard Gill(richard.gill@sheffield.ac.uk)

Dr Steve ThorntonDr Mike Harbottle (Cardiff University)Dr Mike Harbottle (Cardiff University)

What is electrokinetic remediation?The application of a direct current to remove organic or inorganic  H O

Cathode‐ve

Anode+ve

e o e o ga c o o ga ccontaminants from the subsurface.

OH‐

H2 O2

H+

H+

H+

OH

OH H+

H+OH‐

OH‐OH‐

Electroosmosis Surface Charge

Electromigration Voltage

Electrophoresis Particle Charge

How can EK enhance bioremediation?Cathode

‐veAnode+veTransformation of contaminants by 

microorganisms into less harmful c oo ga s s to ess a fusubstances 

Enhanced Growth 

EK‐BIO function

AvailabilityFactors

What effect does EK have on microorganisms?

High Intensities

Low Intensities

H+ OH‐

Low Intensities

?H+

H+H+OH‐

OH

OH‐OHHH OH‐

How can EK be applied?How can EK be applied?Cathode Anode

AmendmentBiological +h lChemical Tank

Energy Example3 month field trial

1500 kWh14.5 p kWh‐1

Suni, S., Malinen, E., & Kosonen, J. (2007). Journal of Environmental Science and Health Part A, 42, 257–267. 

Example of field applicationExample of field applicationEK Bio‐fence 

PCE PCERemediation of VOCs

Groundwater Flow

Treatment Wells

Cathode Anode+ e‐ve +ve

Godschalk and Lageman, 2005Engineering Geology, 77, 3‐4, 225‐231

Conceptual Model and Project PremiseConceptual Model and Project Premise

Amendment 

Effective Ionic 

MobilitySolute 

ConcentrationElectric Field Enhanced

ElectroosmoticFlow

Electrical Conductivity

Electromigrationy Concentration Enhanced 

Biodegradation

Conceptual Model to Experimental Design

Cathode Anode

NO3‐

TolueneToluene

Experimental SetupExperimental SetupCathode Anode

Reservoir T k

Power Supply Cathode AnodeTankSupply

Experiment Aim:Experiment Aim:• Test setup• Migrate NO3‐ across system through glass beadssystem through glass beads• Compare against calculated values

Preliminary ResultsPreliminary ResultsCalculated  Observed

900 100%900

80%

100%

700

800

80%

90%

700

800

(%)

ass (mg)

60%

80%

500

60060%

70%

500

600

Total 

Nitrate Ma

40%300

400

500

40%

50%

300

400

500

N

20%

100

200

300

20%

30%

100

200

300

0%0

100

0 20 40 60 800%

10%

0

100

0 20 40 60 80

Time (hours) Time (hours)

Preliminary ResultsPreliminary ResultsNO3

‐ movement NO3‐ movement

Calculated  Observed

100

120

100

120NO3 movement

Cathod

e

Anod

e

Cathod

e

Anod

e

80 80

100C C

mg L‐1)

60 60

Nitrate (m

20

40

20

40

N

0

20

0 0 0 2 0 4 0 6 0 8 1 00

20

0 0 0 2 0 4 0 6 0 8 1 00.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0Normalised Distance from Cathode Normalised Distance from Cathode

Preliminary resultsPreliminary results70

Electricalhode

node

Observed

60

Electrical Conductivity

As NO3‐ is added

Cath An

40

50

V)

ElectromigrationAs NO3 is added Voltage gradient drops

30

40

Volta

ge (V

Voltage Gradient

20 Implications• NO ‐ successfully moved across

10

NO3 successfully moved across system• Multiple factors influencing migration0

0 0.2 0.4 0.6 0.8 1

4 h 28 h 45 h 69 h

migration• Better understanding of lab setup  

Conclusions and Future WorkConclusions and Future WorkEK t ti l t h bi di ti• EK potential to enhance bioremediation

• Application in physically heterogeneous settings require further investigation:g

Details• Influence of physical heterogeneity represented by1 Influence of physical heterogeneity represented by spatially variable K on NO3

‐migration• V gradient and NO3

‐ concentration on penetration

1

• Influence of physical heterogeneity on EK‐biostimulation

2

• V gradient and NO3‐ concentration on penetration 

and degradationl• Processes in two‐dimensional system

• Couple with modelling3