Environmental Engineering Reference
In-Depth Information
15.5.2.6.
Vaporization - aspiration using shafts
This technique combines the aspiration of air in ground water circulation within
a well. The air of the ground and water of the nappe pass through a stripping engine
installed in the shaft, and the pollutants extracted are recovered with the flow of
outgoing air on the surface (see Figure 5.13). This process makes it possible to treat
the volatile and semi-volatile pollutants.
Figure 15.13.
Diagram of the vaporization process - aspiration using shafts [GER 96]
15.5.2.7.
Washing ground in situ (flushing)
This process uses
in situ
fluid movement to cleanse the unsaturated zone in the
contaminated ground (see Figure 15.14). The fluid pumped into the ground is pure
water or water mixed with normal or synthetic surface-active agents (acids, bases,
surface-active ones, solvents, co-solvents, oxidants or chelating agents to support
damping, solubilization or emulsification of the various contaminants that the
system must recover). At the time of its passage, the fluid takes care of the
contaminants. Once flushed, the solution is extracted, treated and can, in certain
cases, be reinjected. Profitability is improved if biodegradable surface-active agents
