Environmental Engineering Reference
In-Depth Information
To determine the effectiveness of bioaugmentation with vermiculite-car-
ried
P. aeruginosa
strain 64 and strain EPA505, PAH-contaminated soil was
spiked with 2% (by weight) vermiculite treated in two different ways. In one
case, the vermiculite was spiked with Luria-Bertani (LB) broth, a common
growth medium for bacteria (control). In the second case, vermiculite was
treated with LB broth and a mixture of
P. aeruginosa
strain 64 and strain EPA
505 (approximately 1 × 10
6
cells/ml for each strain). Total bacterial numbers
present in the soil over time were compared.
The ability of the vermiculite-carried bacteria to survive in the highly
contaminated soil from the POPILE site was validated using microcosms
incubated at room temperature for 110 days.
7.3.5.5 Biostimulation
Biostimulation was tested using a variety of carbon and nitrogen sources. These
are listed in Table 7.10. Commercially available dried-blood fertilizer performed
well, is readily available, and is cost effective. The dried blood is a pelleted,
slow-release nitrogen fertilizer, normally used in garden applications.
In microcosm tests, contaminated soils were amended with 2%
dried-blood fertilizer and 2% vermiculite containing approximately 10
10
P.
aeruginosa
strain 64 cells/g vermiculite. The presence of dried blood provided
an excellent source of degradable carbon and nitrogen for
P. aeruginosa
strain
64, which resulted in production of rhamnolipid biosurfactant in liquid
cultures. Soil incubated with
P. aeruginosa
strain 64 and dried blood for 5 to
15 days produced a similar surfactant production. To determine the optimal
concentration of dried blood to add to the soil, varying concentrations of
dried blood were added to SMWT soil inoculated with
P. aeruginosa
strain
64. These were plated on LB agar with 0.3% glycerol to promote pyocyanin
pigment production from the
P. aeruginosa
.
The flask studies indicated that cultures immobilized on vermiculite:
•
Maintain a high degree of viability when stored at room temperature
•
Survive well in the presence of the chemical contaminants (i.e., PAHs
and PCP) when introduced into soil
Table 7.10
Fertilizers Investigated as Sources
of Carbon and Nitrogen Supplementation for
PAH Degradation through Biostimulation
Formulation
(% nutrient, N:P:K)
Fertilizer
Miracle Gro plant food
15:30:15
Acid plant food
30:10:10
Bone meal
4:12:0
Dried-blood meal
12:0:0
