Electrokinetic remediation

2. SOIL
POLLUTANTS
PESTICIDES
NUCLEAR WASTE
INDUSTRIAL WASTE
OIL SPILLS

3. According to USEPA there are 23 methods, some are
1. Air Sparging
2. Bioreactor Landfills
3. Electro kinetics: Electric Current Technologies
4. Bioremediation
5. In Situ chemical reduction
6. Natural attenuation
7. Phytotechnologies
8. Multi-Phase extraction
9. Nanotechnology: Applications for Environmental Remediation
10.Solvent extraction
REMEDIATION:
Remediation deals with the removal of pollutants or
contaminants from environmental media such as soil,
groundwater, sediment, or surface water for the general
protection of human health and the environment.

4. ELECTROKINETIC REMEDIATION OF
ORGANIC POLLUTANTS
DIVISION OF AGRICULTURAL CHEMICALS
IARI, NEW DELHI
ANUP KUMAR
ROLL NO. 20367

5. ELECTROKINETIC REMEDIATION:
Electro kinetic remediation, is a technique of using
direct electric current (DC) to remove organic, inorganic
and heavy metal particles from the soil.
SYSTEM COMPONENTS:
• DC source
• Two electrodes
• Electrolytic solutions
• Connecting pipes and wires
• Miscellaneous

6. TRANSPORT MECHANISM

7.  Electro migration: Transportation of ionic pollutants towards
opposite electrodes. Applicable to ionic pollutants
 Electro-osmosis: The net flux of water or interstitial fluid induced
by the electric field
Most commonly occurred
 Electrophoresis: transportation of organic pollutants (OPs) along
with the movement of H+ and OH- ion
 Diffusion: The mass transport due to a concentration gradient, not to
a voltage gradient

8. TYPES OF ELECTROKINETIC
REMEDIATION

9. I. Direct EK technique
II. EK combined with Fenton technique
III. EK combined with surfactants / co-solvents technique
IV. EK combined with biological techniques
V. The method of Lasagna
VI. EK combined with Ultrasonic technique
Huang et al., 2012

10. DIRECT ELECTROKINETIC
TECHNIQUE
DC current
Electric field
generated
Bonds of soil with
OPs broken and
pollutants solubilize
in solvent
Electro-osmotic
flow of electrolyte
towards cathode
removed
 Used for extraction of
phenols, nitrobenzene, and
pesticides

11. EK combined with Fenton
technique DC current
Decomposition of H2O2
and production of OH-
and OH free radical
Oxidising degradation of
OPs by OH free radical
OPs migrated towards
cathode with electro-
osmotic flow
Removed
H202+ Fe2+ OH. +OH- + Fe3+
H2O2 +S OH. +OH- +S+
• Used in the extraction of Phenols,
halogenated hydrocarbons

12. EK combined with surfactants/ co-solvent technique
• Applying surfactants or co-
extractives
• Permeate deep into soil
• Interact with OPs
• Form migratory compounds
through its physicochemical action
of desorption, chelation,
dissolution
• Migration occurs through electro-
osmotic flow and electrophoresis
• Removed
Surfactant used are
• Anionic- Sodium dodecyl sulfate (SDS)
• Cationic-Cetyltrimethylammonium chloride(CTAC)
• Non ionic- Tween-80
• Biological-β-cyclodextrin

13. EK combined with biological techniques:
 Use of micro organism in
reactor cell to degrade into less
toxic products and oxidize to
carbon dioxide & water
 EK increases mobility of the
pollutants and settled at the
place where micro-organism
present
 Degradation occurs by microbes
 Commonly used microbes are
Spigomonas sp., Mycobacterium
sp., Pseudomonas sp.,
Thiobacillus ferrooxidans

14. Bioremediation process
and limitations
 Bioattenuation:
transformation of pollutants by
natural means, limited by
hydrodynamic dispersion in situ
 Biostimulation: Increased
biodegradation by addition to
optimize the N:P:K ratio,
improve redox conditions and
increase bioavailability. Limited
by hydraulic delivery and access
to low permeability zone
 EK-bioattenuation: Increases
bioavailability of contaminants,
naturally occurring nutrients
and electron acceptors
 EK-biostimulation: EK
transport processes allow
addition and delivery of
nutrients, electron acceptors
and surfactants into
contaminated zones regardless
of permeability to increase
bioavailability of limited
substances
Electro kinetic influence
Gill et. al., 2014

15. Contd…
• Bio augmentation:
Introduction of cultured
microbial species adapted to
the biodegradation of a
particular contaminant,
limited by Hydraulic delivery
and access to low
permeability zones.
• Phytoremediation: use of
plants and/or microbes in
root zones to effect
remediation. Limited by
access of contaminants.
• EK-Bioaugmentation- EK
transport of bacterial
population to specific zones
regardless of permeability
where indigenous
community is not adopted.
• EK-Phytoremediation- EK
transport processes
increases the bioavailability
of contaminant.
Gill et. al., 2014

16. The method of Lasagna
Integrative method of many techniques
Loading the polluted soil to the area, extraction done with the
function of adsorption, reduction
OPs migrated to the treatment area mainly by electro-osmotic flow
Removed by solidification & adsorption
EK combined with Ultrasonic technique
The main principle is by use of
Acoustic horn, create unstablity
between the OPs and the interface
Causing breakage of the bond
between OPs and soil, OPs come in
the liquid phase
Removed

17. CASE STUDIES

18. CASE STUDY –I: EK removal of atrazine using direct
technique:
Ribeiro et al., 2005
 SORBATE USED: Atrazine in diethyl ether
 SORBANT USED : Acidic soil having 94% sand
 SOLVENT IN THE ELECTRODE COMPARTMENT: 0.01M NaNO3
 ELECTRIC CURRENT: 0.01 A
 ANODE AND CATHODE: Platinized titanium bars
SET UP:

19. Steps:
 Spiked soil is placed between non spiked soil
 Electric current passed,
 After 48 h current disconnected,
 H2O added in ratio of 1:2.5,
 Extraction done by sonication.
Contd….
Ribeiro et al., 2005

20. Sample Atrazine
present after
spiking (μg)
Atrazine
remained in
soil(μg)
Observations Schematic
representation
1. 19.03 0.050 Close to cathode
2. 19.03 0.080 Middle vertical
section
3. 19.03 0.070 Middle horizontal
section
4. 19.03 0.080 Middle in cross
5. 19.03 0.040 Close to anode
Results:
 Main mechanism of movement :Electro- osmotic flow
 % removed from soil is nearly 98%
Ribeiro et al.,2005
Contd…..

21. CASE STUDY –II: EK removal of 2,4-Dinitrotoluene using co-
extractive technique:
SET UP:
 SORBATE : 2,4- Dinitrotoluene
 SORBENT: kaolinite soil
 SOLVENT : 1% HPCD, Deionized
water
 ELECTRIC POTENTIAL: 1V
DC CURRENT
 ANODE AND CATHODE :
platinum coated iron rod
Khodadoust et al., 2012

22. STEPS:
 Soil taken
 Spiked with 2,4-DNT(480mg/kg soil)
 Mixed homogenously and left for 24 hr.
 Water added so that moisture becomes 35%
 Moist soil placed into the reactor cell
 Cathode compartment was filled with deionized water
 Another setup run with cathode electrolyte 1% HPCD
 Set up kept on at constant 1 V DC/cm for 45 days.
Results:
 Graph shows that less amount of
residue is present when we use 1%
HPCD.
 About 23.3% (water) and 5.8 %
(HPCD) of 2,4 –DNT where present
in soil after completion of
experiment.
 Main mechanism of movement –
Electro-osmotic flow
Khodadoust et al., 2012

23. CASE STUDY –III: EK removal of Diuron from soil
SET UP:
 SORBATE USED: Diuron
 SORBENT: Kaolinite clay
 SOLVENT IN THE ELECTRODE COMPARTMENT: 0.001M Na2SO4
 ELECTRIC CURRENT: DC current of 3 V and 5 mA
 ANODE : Titanium sheet covered with RuO2
 CATHODE: Stainless Steel
Polcaro et al., 2007

24. Contd…
Steps:
 Soil fortified with Diuron taken into
cell
 System was set up according to figure.
 Run for 50 hours
 At the time of 20, 35, 50 hours soil
sample taken and analyzed
Clay
type
Pollutant Treatment
time(h)
Initial
contaminant
(mg)
Contaminant
present in
soil (mg)
% contaminant
removed
Kaolinite Diuron 20 2.19 1.49 31.3
Kaolinite Diuron 35 2.19 0.79 61.4
Kaolinite Diuron 50 2.19 0.29 86.7
Polcaro et al., 2007

25. Contd……….
Results:
Approximately 90% of the diuron removed.
Main method of flow is electro-osmotic flow
Accumulation occurs in catholyte.
Polcaro et al., 2007

26. CASE STUDY –IV: EK removal of 2,4-Dichlorophenol from soil
using Lasagna technique
SET UP:
 SORBATE USED: 2,4-dichlorophenol
 SORBENT: Sandy loam soil
 SOLVENT IN THE ELECTRODE COMPARTMENT: 0.01 M KNO3
 ADSORBANT USED: Activated bamboo charcoal
 ELECTRIC POTENTIAL: DC current of 1V
 ANODE AND CATHODE: Graphite

27. Steps:
 Soil with proper moisture taken in
reactor cell
 Treatment zone filled with bamboo
charcoal
 Cathode and anode compartments
filled with electrolyte and
electrodes inserted
 System connected to DC source
 Set up kept on for 11 days
Results:
 About 54.92 % in 24 h and at
last of experiment 93.6% of 2,4-
dichlorophenol removed.
 Main method of flow is electro-
osmotic flow
Ma et al., 2010

28. CASE STUDY –V: In-situ removal of creosote by the use of EK
enhanced bioremediation:
SET UP:
 SORBATE USED: Creosote
 SORBENT USED: Contaminated soil
 ANODE: Stainless steel of length 4m
 CATHODE: Zn plated steel of length 5m
 ELECTRIC POTENTIAL: 0.46 V /cm
Suni et al. 2007

29. Steps:
Cathode installed in middle of contaminated area,
6 anodes installed forming a circle around cathode with radius
2.5 m,
Vertical pipes with perforation from 0.5-4 m installed beside
anode,
Extraction pipe down to 5 m besides cathode is inserted,
Anode connected in series and then connected to source of
current,
 Water pumped from the groundwater well to supply to nearby
treatment equipment,
 water first run through an oil separator to separate pure
creosote and then treated in a biological aerated carrier matrix
reactor with added nutrients,
The water was run through an activated carbon filter before
circulating back to the soil. Suni et al. 2007

30. Results:
Distance
from
cathode
Left side of cathode Right side of anode
Initial conc.
(mg/kg dry wt.)
Final conc.
(mg/kg dry wt.)
Initial conc.
(mg/kg dry wt.)
Final conc.
(mg/kg dry wt.)
1.25 m 4.3 1.04 7.26 0.39
2.5 m 5.2 3.51 20.16 6.64
 About 78% of creosote were degraded by microbes,
 Main method of flow : Electro-osmotic flow
Suni et al. 2007

31. The other case studies are:
1. Removing OPs from soils by direct EK technique
Enhanced
method
Contamination Soil type Removal
efficiency
references
Direct EK 2,4-
dichlorophenol
Sandy loam 73.4% Fan et al.,
(2007)
Direct EK Trichloroethylene Clay soil 97% Jin et al.,
(2005)
2. Removal of OPs from soils by EK combined with Fenton technique
Enhanced
method
Contamination Soil type Removal
efficiency
references
EK-Fenton
process
Trichloroethylene Loamy sand 75% Yang et al.,
(2001)
EK-Fenton
process
Petroleum
hydrocarbon diesel
Kaolinite 97% Tsai et al.,
(2010)

32. Contd….
3.Removal of OPs in soil with surfactants
Surfactant
used
Contamination Soil type Removal
efficiency
references
Triton X-
100
Hexachlorobenzene Sandy soil 94% Wan et al.,
(2010)
HPCD* 2,4-DNT Silty soil 83% Jiradecha et al.,
(2006)
Enhanced
method
Contamination Soil type Removal
efficiency
references
Bioremediation Vinyl chloride Clayey soil 90% Tiehm et al.,
(2009)
Biostimulation Diesel fuel Loamy sand
soil
64% Pazos et al.,
(2012)
4.Removal of OPs in soil with biological techniques
*HPCD: Hydroxypropyl-β-cyclodextrin

33. Contd…
5.The lasagna technology
6.Removal of OPs in soil with ultrasonic technique
Enhanced
method
Contamination Soil type Removal
efficency
references
Lasagna
technology
Trichloroethylene Sandy clay
loam
>99% Ho et al.,
(1999)
Lasagna
technology
2,4-Dichlorophenol Sandy loam
soil
84% Jian et al.,
(2010)
Enhanced
method
Contamination Soil type Removal
efficency
references
Ultrasonic
technique
Hexachlorobenzene Kaolinitic
soil
70-83% Pham et al.,
(2009)
Ultrasonic
technique
phenanthrene Natural clay 90% Chung et al.,
(2005)

35. A green remediation technology developed in recent
years, used for treatment of soil contaminated by heavy
metals and OPs
In direct EK technique neutralization of soil can be
easily realised, immobilization near the electrodes can
be prevented
 EK-Fenton method can degrade different kinds of OPs
with a high efficiency and a low cost

36. Surfactants, co-extractives enhanced EK technique can be
used to remove many kinds of OPs, easy to operate, highly
permeable and at a reasonable cost
EK with biological techniques, a green remediation
technology, potentially capable of treating multiple
contaminants in low permeability soil
 Ultrasonic combined with EK technique particularly
suitable for the degradation of both ionic as well as non
ionic pollutants

37.  More research should have be done on in-situ
extraction of organic pollutants
Exploring new remediation methods after
optimizing parameters and combination of
current soil remediation techniques
Developing new types of pollution free
surfactants and identifying new types of bacteria
with high degradation efficiency

38. Investigating the impact of geochemistry
reaction such as adsorption, dissolution and
sedimentation on remediation process
Combination of multidiscipline EK
remediation technique will continuously be
developed