Page 258 - Materials Chemistry, Second Edition
P. 258
Groundwater Remediation 241
Q , C in Q , C out
w
a
Q , C out Q , G in
w
a
FIGURE 6.6
Schematic diagram of a packed-column air stripper.
An air-stripping system creates air and water interfaces to enhance mass
transfer between the air and liquid phases. Although there are several sys-
tem configurations commercially available, including tray columns, spray
systems, diffused aeration, and packed columns (or often called packed tow-
ers), use of packed towers is the most popular alternative for groundwater
remediation applications (Figure 6.6).
6.4.2 Design of an Air-Stripping System
In a packed-column air-stripping tower, the air and the impacted groundwa-
ter streams flow countercurrently through a packing column. The packing
provides a large surface area for VOCs to migrate from the liquid stream
to the air stream. A mass-balance equation can be derived by letting the
amount of COCs removed from the liquid be equal to the amount of the
COCs that enter the air:
QC( ) = Q G( −G ) (6.16)
w in − C out a out in
