Fundamentals of electrokinetics - In-Situ Remediation of Arsenic-Contaminated Sites - page 107

5.5 PROSPECTS FOR ELECTROKINETIC REMEDIATION

The soil remediation technologies developed so far can be classified into two groups depending
on the stage of development. The first generation (1G) technologies include ex-situ ones, such
as soil washing, land farming, incineration, and compositing. These technologies are considered
to be economically ineffective, even though they have shown a relatively higher performance.
The next generation (2G) technologies comprise in-situ ones, such as soil flushing, soil vapor
extraction, and electrokinetics. The 2G technologies are known to be effective for the removal of
contaminants and are economically viable. However, their major drawback is that their overall
performance is totally dependent on the type and concentration of contaminant. Especially, the
sole (individual) in-situ technology cannot be effectively operated in removing multiple (mixed)
contaminants, such as multiple heavy metals, multiple organics, or multiple metals and organ-
ics. To overcome the drawbacks of 2G technologies and to create new synergetic effects, third
generation (3G) technologies have recently been developed and investigated through integra-
tion and/or coupling of different individual technologies, for example, bioremediation/SS, soil
flushing/phytoremediation, and so on. The major advantage of 3G technologies is that they are
independent of the type and concentration of contaminant, and therefore, can be used effectively to
remove mixed contaminants in various levels of concentration in soil. Integrated 3G technologies
are expected to be more developed in the future, and they may be the key solution for remediation
of contaminated soils. From this point of view, the electrokientic remediation should be coupled
with other technologies to improve its performance and overcome its main defects. For example,
electrokinetics incorporated with bioremediation can effectively remediate soils contaminated
with multiple contaminants such as inorganics and organics. When determining the sequence of
integration of different technologies, one must consider the properties of soils and contaminants.
The 3G technologies related to electrokinetics, which are currently ongoing and also expected to
come into spotlight in the future, are exemplified as follows:

• Electroheated extraction.

• Electrokinetic biobarrier.

• Electrokinetic chemical oxidation/reduction.

• Electrokinetic permeable reactive barrier (PRB).

• Electrokinetic fence.

• Electrokinetic stabilization.

• Electrokinetic chemical oxidation/reduction.

• Electrokinetic phytoremediation.

• Electrokinetic bioremediation (or bioelectric remediation).

Through integration and/or coupling, the efficacy of electrokinetics could be extended to
remediate various contaminated media including sediment and groundwater as well.

ACKNOWLEDGEMENTS

The authors thank Professor Ouhadi and two anonymous reviewers for their valuable and con-
structive comments. This work was supported by Dr. S.-O. Kim's 2012 sabbatical program funded
by Gyeongsang National University.

REFERENCES

Acar, Y.B. & Alshawabkeh, A.N.: Principles of electrokinetic remediation. Environ. Sci. Technol . 27 (1993),
pp. 2638-2647.
Al-Hamdan, A.Z. & Reddy, K.R.: Geochemical reconnaissance of heavy metals in kaolin after electrokinetic
remediation. J. Environ. Sci. Health A41 (2006), pp. 17-33.