Biomedical Engineering Reference
In-Depth Information
(a)
Determine v
O
2
, v
NH
3
, v
X
, v
W
, and v
CO
2
,ifYF
X/S
¼
0.4 g-X/g-S.
(b)
Determine the yield factors YF
X/O
2
and YF
X/NH
3
.
(c)
Determine the degree of reductions for the substrate, bacteria, and the respiratory
quotient RQ
v
O
2
) for the organisms.
3.16. Biological denitrification of nitrate-containing wastewaters can be described by the
following overall reaction.
¼
v
CO
2
/(
NO
3
H
þ
/
v
MeOH
CH
OH
þ
v
X
C
H
NO
2
þ
v
N
2
N
2
þ
v
W
H
O
þ
v
CO
2
CO
3
5
7
2
2
0.5 mol-X/mol-N-Substrate.
3.17. Polyhydroxyalkanoates (PHAs) are a family of polyesters synthesized by numerous
bacteria as an intracellular carbon and energy storage compound, especially when one
of the essential nutrients is lacking preventing the cells from multiplication. One
important class of PHA: PHBV, is produced from sugars. PHBV synthesis reaction
during anaerobic fermentation is given by:
Determine v
MeoH
, v
X
, v
N
2
, v
W
, and v
CO
2
,ifYF
X/S
¼
v
PHA
Þ
þ
v
S
CH
O
/
OCH
ð
CH
3
Þ
CH
C
ð
O
CO
2
þ 3
H
2
O
2
2
(a)
Determine the stoichiometrical coefficients: v
S
and v
PHA
.
(b)
Determine the PHA yield factor Y
PHA/S
.
3.18. It has been reported that when bacteria K. fragilis is used in the aerobic fermentation
of glucose using dissolved ammonia as a nitrogen source produces a biomass of
atomic composition CH
1.75
O
0.52
N
0.15
and ethanol C
2
H
5
OH. The following yield
factors have been reported: YF
X/S
¼
0.407 C-mol/
C-mol. Determine the other yield factors for this fermentation. What fraction of the
carbon atoms present in glucose is converted to ethanol?
3.19. When the bacterium Zymomonas mobilis is used to produce ethanol from glucose in an
anaerobic process with ammonia as the nitrogen source, it is found that bacteria
biomass is produced to the extent of 0.06 C-mol per C-mole of glucose. The biomass has
an elemental composition of CH
1.8
O
0.5
N
0.2
. What are the fractional yield of ethanol, the
amount of ammonia used, and the amount of carbon dioxide produced per C-mole of
glucose consumed?
3.20. A considerable amount of methane is produced in Norway from its North Sea oil and
gas wells. Some of this methane is converted to methanol by partial oxidation and then
biochemically converted to biomass that is used as animal feed. The reported
stoichiometry for the biochemical reaction is
CH
0.569 C-mol/C-mol and YF
CO
2
/S
¼
OH
þ 0:731
O
2
þ 0:146
NH
3
/ 0:269
CO
2
þ 0:731
X
3
What is the atomic composition of the biomass produced?
3.21. Ethane costs $0.05/lb and ethylene sells for $0.18/lb. A typical ethylene plant produces
1 billion pounds/year.
(a)
What are the annual sales?
(b)
If we had a perfect process, what must be the cost of producing ethylene if we want
a profit of 10% of sales?
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