Environmental Engineering Reference
In-Depth Information
potassium phosphate buffer (pH 7) into each vial. The six vials were vortexed
horizontally at one time for 10 min at the maximum speed and allowed to
stand for 3 min to permit sedimentation of soil particles from the water
column. Serial dilutions were prepared and spread onto Luria agar plates
containing rifampicin. Immediately following cell extraction, the microcosms
were frozen at -20˚C. PCBs were then extracted from these same vials and
analyzed using a GC.
Survival of
Rhodococcus
sp. strain RHA1(pRHD34::
fcb
) and
Burkholderia
xenovorans
strain LB400(pRO41::
ohb
) was greatly improved when vermiculite
was used as an inoculum carrier. Growth did occur in the presence of chlo-
robiphenyl with and without vermiculite. However, the growth was an order
of magnitude greater when vermiculite was used as a carrier.
6.4.1.11 Recommendations for inoculum delivery during pilot test
Recommendations for inoculum delivery during pilot test:
1.
Inoculation density
a.
Organisms will be inoculated at 10
6
cells/g.
2.
Vermiculite
a.
Use 3 g vermiculite/100 g of soil (for slurry, use weight of soil +
water) (3% w/w).
b.
Use a medium- to fine-grade vermiculite for greater sur-
face-to-volume (mass) ratio.
3.
Vermiculite impregnation
a.
Cell inoculum is diluted to bring the total water content of the
vermiculite to a ratio of 1 ml to 1 g.
b.
Diluted cells are mixed into vermiculite immediately after they
are harvested until homogenous.
4.
Addition of impregnated vermiculite to soil
a.
Impregnated vermiculite is added to soil immediately following
addition of cells to vermiculite.
b.
Homogeneity of vermiculite and soil in high solids (land farming)
and medium solids treatments must be reached.
6.4.1.12 Compatibility of anaerobic and aerobic phases in
remediation process
In the anaerobic-aerobic bioremediation system to be employed, FeSO
4
will
be added to the soil to enhance anaerobic reductive dechlorination. To find
out if residual FeSO
4
or the resulting FeS from this process will have a
negative influence on the efficiency of aerobic metabolism, we grew LB400
and RHA1 in the presence of these Fe(II) compounds (Figure 6.20).
