Environmental Engineering Reference
In-Depth Information
15.5.2.3.
Biosparging
This process makes it possible to locally treat the saturated zone (dissolved,
adsorbed). The technique involves injecting air through vertical or horizontal wells
into the formation below the sheet of water (see Figure 15.11).
The air injected is propagated in the saturated zone by creating favored channels
of circulation. In parallel, the dissolution of oxygen in air in the aqueous phase
makes it possible to increase the aerobic biodegradation of certain contaminants
(biosparging). Furthermore, by installing interfaces between the air and the phases
present in the ground (air/water, air/ground, air/product), air injection favors the
evaporation of volatile chemical substances present in the saturated zone, whereas
those presented in a pure state are below the aqueous capillary fringe. The vapor
recuperation network installed in the unsaturated zone enables the possible
retreatment of surface pollutants. As previously, the pollutants that are potentially
treatable using the biosparging technique are biodegradable pollutants and those
treatable using air injection are volatile pollutants.
Figure 15.11.
Diagram of the biosparging process (coupled with bioventing) [GER 96]
As with any technology, there are limitations with its use and limitations. These
limitations are given in Table 15.8.
