Environmental Engineering Reference
In-Depth Information
without the need for energy contribution to be effective. Active treatment systems
require an energy contribution in order to reach the level required for cleaning.
Active treatment systems are more expensive than passive treatment systems.
Each technique suggested can have recourse to four different processes:
biological, physicochemical, thermal, and the electrokinetic processes, which seem
to be more innovative.
In what follows, we present the objectives (destruction, extraction or
encapsulation) of treatment as well as the principal types of pollutants treated, with a
brief explanation of how the principal existing techniques work. It is important to
stress that this chapter does not contain a complete inventory of current
environmental remediation techniques. A summary of the available techniques and
their applications is given in Tables 15.1 and 15.2.
Soil
excavation?
Technique/
category
Technique/
process
Example(s)
Note(s)
Yes
(off-site)
Confinement
Landfill
landfill center, cell breakdown
Treatment
Chemical
neutralization, extraction using
solvents
Treated soil can be
stored in a drain or
can be returned to site
Physical
soil flushing,
stabilization/solidification,
vitrification
Biological
“biopiles”, biomounds,
bioreactors
Thermal
incineration, vitrification
No (
in-situ
) Confinement Pump and
treat
vertical shafts, horizontal shafts
Passive and active
confinements are
possible; in the case
of “pump and treat”
pumping is used to
control the hydraulic
gradient and to tap
off the polluted
water; treatment is
carried out off-site
Covering
system
traditional covers, geochemical
covers
Vertical
barriers
watertight molded walls, sheet
piling, biobarriers, chemical
barriers,
cement-grouted curtains
Horizontal
barriers
watertightness with injection of
cement grout
Treatment
Chemical
oxidation, chemical reduction
The technologies
followed by an
asterisk (*) require
the removal of gas or
liquids and off-site
treatment; passive
and active treatments
are possible
Physical
soil flushing*, stabilization/
solidification, vitrification, air
sparging*, vacuum extraction,
electro-chemical rehabilitation
Biological
natural attenuation, bioventing,
bioslurping, biosparging
Thermal
vapor injection*, radio
frequency heating*,
vitrification*
Table 15.2.
Classification of techniques for the rehabilitation of polluted soil [SHA 00]
