Environmental Engineering Reference
In-Depth Information
The choice of a technique used to remove particular contamination requires
comprehension of the principle of its operation and application constraints. This is
closely related to environmental considerations (pedology, pollutants present,
biological breakdown, biotransformation, toxicity, risks incurred while using such or
such treatment, etc.).
This chapter will examine various environmental remediation techniques and
will try to help with the choice of a suitable technique able to function in an optimal
way under the conditions of the medium considered. It will be noted that it is
possible to combine certain methods according to pollutants to be dealt with.
15.2. Pollution control techniques
Pollution control techniques are varied. They can be classified according to their
procedure, that is to say:
−
in situ
techniques;
− excavation techniques;
− insulation and containment techniques.
The
in situ
techniques are those whose environmental remediation takes place
without excavation. Generally, these techniques are less expensive than those that
involve excavation. Indeed, the saving is due to the fact that we should not have
recourse to excavation. There is therefore no issue with management of the grounds
(handling, transport, storage) nor of setting up the site. On the other hand, these
techniques are slower and cumbersome in the case when sites are used for clean
activities.
The treatment with excavation techniques seems more expensive but is more
effective. We distinguish between treatment with excavation
in situ
and treatment
with excavation outside the site. These last techniques require the polluted grounds
to be excavated and taken to processing centers.
Insulation and containment techniques isolate pollution and do not treat it. The
traditional process consists of the construction of an artificial barrier between the
pollution and the vicinity (argillaceous barrier, tight slurry trench walls, sheet piled
walls, etc). This aspect will be discussed in Chapter 8.
Another distinction needs to be made between active and passive techniques.
The terms “liability” and “credit” have a different significance according to whether
reference is made to containment or treatment. These terms can have a different
significance in various parts of the world. In North America, for example, passive
