Electrochemical treatment technologies
Electrokinetic technology
Electrodialytic remediation is an innovative
technology, which aims to remove heavy metals, organics and radionuclides from
contaminated soil, sludge, wood and other, contaminated media. It involves an
application of a low level direct current (40 – 100 mA, which induces the
movement of ionic
species in the media-water solution towards the oppositely charged electrode (electro-migration),
a bulk flow of moisture present in the
contaminated media from the anode to the cathode (electro-osmosis) and a
movement of charged particles or colloids in the applied electric field (electrophoresis).
The success of electrochemical remediation depends on the specific conditions
encountered in the field, including the types and amount of contaminant present,
soil type, pH and organic content. Once the remediation process is over,
extraction and removal of heavy metal contaminants are accomplished by
electroplating at the electrode, precipitation or co-precipitation at the
electrode, pumping water near the electrode, or complexing with ion exchange
resins.
To increase the efficiency of electrokinetic
remediation, it is necessary to employ different electrode material, number and
spacing. By optimizing the selection of suitable electrode materials, coupled
with the application of the appropriate number of electrodes and electrode
spacing, it is expected that the remediation time will be drastically reduced.
In addition, the methodology being investigated in this study will reduce
inefficiencies in electrical field distribution. The effect of various electrode
materials such as silver and graphite, and the influence of changes in the
number and the layout of the electrodes on the overall remediation efficiency
and time is investigated and evaluated. Experiments with one, two and three
one-dimensional anode system have proved that remediation efficiencies as high
as 91% can be attained.
The major applications of the EK
The primary applications of the electrokinetics
is the removal of contaminants from any porous low and high permeability
polluted coarse and especially fine-grained media and the removal of water, i.e.
the compaction of soils and sludges. In addition, EK is suitable to remediate
medias with low concentrations of chemicals, i.e. adsorbed chemicals, which
should be removed from the particles surfaces.
1. Remediation of the contaminated soils and
sediment:
mainly to remove heavy metals, organic compounds and radio-nuclides from low
permeability fine-grained soils by applying electrodes directly into the soil or
into the conductive solution.
2. Remediation of the contaminated timber
waste: to remove the heavy metals from highly contaminated CCA and other
contaminated timber waste.
3. Remediation of contaminated sludge:
to purify the sludge contaminated with heavy metals and toxic organic compounds
such as pesticides. Additionally it aims to remove pathogens, viruses and other
parasitic organisms.
4. Remediation of contaminated fly ash:
to remove highly concentrated heavy metals from fly ash, which are left after
the incineration of waste containing heavy metal contaminants.
5. Treatment of gypsum contaminated soils.
6. Remediation of wastewater: the
removal of organic toxic compounds, coagulated matter, heavy metals, and
colloids from the highly contaminated wastewaters.
7. Removal of salts from water: to
separate salts from the high salinity waters.
8. Dewater the sludge or soil : to
remove the excess of water present in the sludge or soil to compact the medium
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