Environmental Engineering Reference
In-Depth Information
Table 6.7
Rome, GA, Soil Chemical Characterization
Concentration
(mg/g)
Concentration
a
(μg/g)
Nutrients
Metals
TKN
TP
TOC
0.51
0.58
6.27
B
As
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Zn
K
Na
Mg
Ca
Fe
Al
21.27
26.99
6.17
90.25
15.97
20.70
47.77
427.67
6.87
70.44
457.47
287.37
281.65
8.16
30.82
261.84
1.79
1057.46
a
Metal concentration is on a dry basis.
6.5.3 Pilot-scale demonstration
The reactor setup consists of three reactors (treatments) for each solids load-
ing under three bioremediation options. The reactors used for three different
solids loadings are illustrated in Figures 6.27 through 6.29. The low solids
reactor (Figure 6.27) consisted of a stainless steel 430-gallon tank with dimen-
sions of 56 in. high and 47∫ in. internal diameter. The reactor has a
cone-shaped bottom for convenient unloading. The reactor was equipped
with a variable-speed agitator fitted with two propellers for mixing and
aerating the slurry. The reactor was similar to the traditional bioslurry reactor
commonly used for the
ex situ
treatment of contaminated soils and sedi-
ments. This reactor uses excessive water (90 to 95%) to create anaerobic
conditions, to maximize the distribution of microbial amendments, and to
enhance the mass transfer. Inherently, the treatment times are considerably
shorter in such types of systems; however, the postremediation handling of
excessive water generated from dewatering the treated material is a major
disadvantage of these systems.
The medium solids reactor shown in Figure 6.28 is a state-of-the-art
shaftless screw reactor capable of mixing soil slurries with solids content up
to 70% w/w. The 140-gallon medium solids reactor has a footprint of 16.5
ft
2
. The reactor was fitted with three shaftless screws to mix and convey the
high solids slurries. The medium solids reactor is a novel idea in bulk
material mixing and conveying. The shaftless screws are 1.93 m in length
