Biomedical Engineering Reference
In-Depth Information
3.11. The growth of baker's yeast (Saccharomyces cerevisiae) on glucose may be simply
described by the following equation:
C
H
O
6
þ 3
O
2
þ 0:48
NH
3
/ 0:48
C
H
NO
3
ð
yeast
Þþ4:32
H
O
þ 3:12
CO
2
In a batch reactor of volume 10
5
L, the final desired yeast concentration is 50 g/L. Using
the above reaction stoichiometry:
(a)
Determine the concentration and total amount of glucose and (NH
4
)
2
SO
4
in the
medium.
(b)
Determine the yield factors YF
X/S
(biomass/glucose) and YF
X/O2
(biomass/
oxygen).
(c)
Determine the total amount of oxygen required.
(d)
If the rate of growth at exponential phase is r
X
¼
6
12
6
10
2
0.7 g/(L
$
h), determine the rate of
oxygen consumption, g-O
2
/(L
$
h).
(e)
Calculate the heat-removal requirements for the reactor.
3.12. The growth of S. cerevisiae on glucose under anaerobic conditions can be described by
the following overall reaction:
6
v
N
NH
3
/ 0:59
0:45
ð
Þþ0:43
3
þ 1:54
C
H
O
CH
N
O
biomass
C
H
O
CO
6
12
1:74
0:2
3
8
2
þ
v
EtOH
C
H
OH
þ
v
W
H
O
2
5
2
(a)
Determine the biomass yield factor: YF
X/S
.
(b)
Determine the product yield factor: YF
EtOH/S
,
YF
CO
2
=S
, and
YF
C
3
H
8
O
3
=S
.
(c)
Determine the coefficient v
N
.
3.13. Aerobic growth of S. cerevisiae on ethanol is simply described by the following overall
reaction:
C
2
H
OH
v
O
2
O
2
v
NH
3
NH
3
/
v
X
CH
N
O
0:408
þ
v
CO
2
CO
2
þ
v
W
H
O
5
1:704
0:149
2
(a)
Determine the coefficients v
O
2
, v
NH
3
, v
X
, and v
CO
2
, where the respiratory quotient
RQ
0.66.
(b)
Determine the biomass yield factor, YF
X/S
, and oxygen yield factor, YF
X/O
2
(g-X/
g-O
2
).
3.14. Aerobic degradation of benzoic acid by a mixed culture of microorganisms can be
represented by the following reaction.
¼
v
CO
2
/(
v
O
2
)
¼
C
H
COOH
ð
substrate
Þ
v
O
2
O
2
v
NH
3
NH
3
/
v
X
C
H
NO
2
ð
biomass
Þ
6
5
5
7
þ
v
W
H
O
þ
v
CO
2
CO
2
2
(a)
Determine v
O2
, v
NH3
, v
X
, v
W
, and v
CO2
if the respiratory quotient RQ
¼
v
CO
2
/
0.9.
(b)
Determine the yield factors, YF
X/S
and YF
X/O
2
.
(c)
Determine degree of reduction for the substrate and bacteria.
3.15. Aerobic degradation of an organic compound by a mixed culture of organisms in
wastewater can be represented by the following reaction.
C
(
v
O
2
)
¼
H
O
3
v
O
2
O
2
v
NH
3
NH
3
/
v
X
C
H
NO
2
þ
v
W
H
O
þ
v
CO
2
CO
3
6
5
7
2
2
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