Environmental Engineering Reference
In-Depth Information
25
Phenanthrene
Fluoranthene
Fluorene
Acenaphthene
Pyrene
Anthracene
Chrysene
Benz[a]anthracene
20
15
10
5
0
0.0
0.5
1.0
1.5
2.0
2.5
Crude Surfactant Concentration (CMC)
Figure 7.19
Concentrations of PAHs in aqueous extracts of POPILE wood treatment
site soil at two concentrations of crude biosurfactant produced by
P. aeruginosa
strain
64.
may be required to increase the solubility of these compounds in the aqueous
phase of the system. Soils are complex habitats, and a wide variety of phys-
ical and chemical factors affect the bioavailability of hydrophobic com-
pounds. Results from aqueous extracts of the soil indicate that the surfactant
compounds produced by
P. aeruginosa
strain 64 can increase the concentra-
tion of at least some of the components of creosote in the aqueous phase of
the system. Increases in aqueous concentrations were generally in direct
proportion to the amount of surfactant present. These results suggest that
inclusion of
P. aeruginosa
strain 64 surfactant in the land-farm operation could
dramatically increase the accessibility of PAHs to soil bacteria.
7.4.1.3 Nutrient amendment
The response of the added bacteria to the presence of the dried-blood nutri-
ents was both subjectively and objectively apparent.
P. aeruginosa
strain 64
“blooms,” coloring the soil a dull greenish color (presumably because of the
production of pyocyanin, which is a fluorescent pigment), producing a char-
acteristic odor, and, in essence, emulsifying the soil (soil suspensions in water
remain in suspension without mixing). This is illustrated in Figure 7.17,
where the left tube is the control, the middle tube is the soil treated with
dried-blood fertilizer and vermiculite, and the right-hand tube is the sample
treated with dried-blood fertilizer and
P. aeruginosa
strain 64 on a vermiculite
carrier. Soil suspensions following treatment with
P. aeruginosa
strain 64 and
the dried blood have reduced surface tension. To determine the effect of
biosurfactant production
in situ
, we extracted subsamples of the soil with
water and measured the PAHs that could be washed from the soil in the
