Therefore, it is necessary to separate the weathered oil particles/conglomerates from
the contaminated soil prior to bioremediation.
To solve this problem, DEKONTA has developed an innovative separation
method utilizing the difference in specific gravity of weathered oil particles/conglomerates (typically 1.1–1.5 g/cm
3 ) and sand/stone (typically 2.2–2.7 g/cm
3 ).
Dense media separation process is commonly used for processing of coal and
some minerals. Nevertheless, it has not been applied to remediation purposes so far.
The principal of the process is that if a mixture of particles differing in their
specific gravity is submersed in heavy liquid of suitable density, lighter density
particles naturally float, while those denser than the liquid sink. Mixture of fine
media material, such as magnetite or ferrosilicon, suspended in water is used to
produce media (slurry) of appropriate specific gravity.
Prescreened input material is fed to the heavy media vessel that has the required
media specific gravity. The light density material floats and is discharged from the
float section of the vessel, while the higher specific gravity material sinks and is
discharged from the sink section of the vessel. The material is discharged on drain
and rinse screens in order to separate the material that drains through from the
remainder on the screen. The washed medium needs to be re-concentrated and is sent
back to the magnetic separator circuit for recovery. From the magnetic separator, the
medium reports to the densifier or the media thickener, where it is pumped back to
the heavy media separator to maintain the proper specific gravity of the vessel and
replace the medium continuously lost with the discharge of the float and sink
material.
The sink product from the DMS process (contaminated soil/sand) is subsequently
treated by bioremediation. The float product (weathered oil particles/conglomerates)
with the average concentration of petroleum hydrocarbons 30% as minimum is used
as an alternative fuel.
Technological scheme of the DMS process is provided below (Fig. 26.10).
26.6 Conclusion
Decontamination of large volumes of soils polluted by petroleum hydrocarbons is
most often carried out by excavation and subsequent ex situ bioremediation. In case
that the soil contains macroscopic particles of weathered oil or conglomerates
formed by mixture of weathered oil and soil admixtures, efficiency of bioremediation of such material has its limitations. In that case the new technology of dense
media separation can be used as the first step to separate a highly contaminated
material and make the material suitable for biodegradation.
26 Field Study X: Oil Waste Processing Using Combination of. . .
543
the contaminated soil prior to bioremediation.
To solve this problem, DEKONTA has developed an innovative separation
method utilizing the difference in specific gravity of weathered oil particles/conglomerates (typically 1.1–1.5 g/cm
3 ) and sand/stone (typically 2.2–2.7 g/cm
3 ).
Dense media separation process is commonly used for processing of coal and
some minerals. Nevertheless, it has not been applied to remediation purposes so far.
The principal of the process is that if a mixture of particles differing in their
specific gravity is submersed in heavy liquid of suitable density, lighter density
particles naturally float, while those denser than the liquid sink. Mixture of fine
media material, such as magnetite or ferrosilicon, suspended in water is used to
produce media (slurry) of appropriate specific gravity.
Prescreened input material is fed to the heavy media vessel that has the required
media specific gravity. The light density material floats and is discharged from the
float section of the vessel, while the higher specific gravity material sinks and is
discharged from the sink section of the vessel. The material is discharged on drain
and rinse screens in order to separate the material that drains through from the
remainder on the screen. The washed medium needs to be re-concentrated and is sent
back to the magnetic separator circuit for recovery. From the magnetic separator, the
medium reports to the densifier or the media thickener, where it is pumped back to
the heavy media separator to maintain the proper specific gravity of the vessel and
replace the medium continuously lost with the discharge of the float and sink
material.
The sink product from the DMS process (contaminated soil/sand) is subsequently
treated by bioremediation. The float product (weathered oil particles/conglomerates)
with the average concentration of petroleum hydrocarbons 30% as minimum is used
as an alternative fuel.
Technological scheme of the DMS process is provided below (Fig. 26.10).
26.6 Conclusion
Decontamination of large volumes of soils polluted by petroleum hydrocarbons is
most often carried out by excavation and subsequent ex situ bioremediation. In case
that the soil contains macroscopic particles of weathered oil or conglomerates
formed by mixture of weathered oil and soil admixtures, efficiency of bioremediation of such material has its limitations. In that case the new technology of dense
media separation can be used as the first step to separate a highly contaminated
material and make the material suitable for biodegradation.
26 Field Study X: Oil Waste Processing Using Combination of. . .
543