Biomedical Engineering Reference
In-Depth Information
Fermentors
Base nutrients
Equilibration
tank
Static mixer
Extraction
wells
Injection
lines
15 m
Delivery well gallery
D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15
Figure 9.12. Delivery well gallery and aboveground system used to create a biocurtain in the
demonstration-scale experiment conducted at Schoolcraft, Michigan.
transported from an injection well to a monitoring well located 1 m away. Both findings
impacted the design and operation of the demonstration-scale experiment.
The primary focus of the demonstration-scale experiment was to improve chemical and
organism delivery to achieve uniform and reliable CT removal to levels below the MCL. As
shown in Figures
9.12
and
9.13
, this was accomplished using a “picket fence” of extraction/
injection wells located orthogonal to the direction of groundwater flow (transect C in Fig-
ure
9.13
), spaced 1 m apart, and coupled to an aboveground system for chemical and organism
delivery (Dybas et al.,
2002
). Weekly operation of this system made it possible to colonize a
large region of the subsurface with
P. stutzeri
KC and to sustain long-term CT degradation to
levels below the MCL.
For the pH adjustment phase, groundwater was extracted from the aquifer, adjusted to pH
8 using sodium hydroxide and injected back into the aquifer. This process was repeated until the
pH at monitoring wells located 1-m downgradient from the delivery well gallery was deemed
high enough for inoculation with
P. stutzeri
KC.
Three inoculations were evaluated in the two field studies conducted to date, all using
aerobically-grown
P. stutzeri
KC. The inoculation strategies included: (1) a single inoculation
without recirculation in the pilot-scale experiment; (2) a single inoculation with recirculation in
the demonstration-scale experiment; and (3) a reinoculation in the demonstration-scale
Search WWH ::
Custom Search