Biomedical Engineering Reference
In-Depth Information
TABLE P12.11
D, h
L
1
Pesticides
S
, mg/L
X
, mg/L
0.05
15
162
0.11
25
210
0.24
50
250
0.39
100
235
0.52
140
220
0.7
180
205
0.82
240
170
Assuming the pesticide concentration in the feedwastewater streamas
S
0
¼
500 mg/L,
m
max
, and
K
S
.
12.12. The maximum growth yield factor for
B. subtilis
growing on methanol is 0.4 g-X
/
g-S.
The heat of combustion of cells is 21 kJ/g-cells and for substrate it is 30.5 kJ/g.
Determine the metabolic heat generated by the cells per unit mass of methanol
consumption.
12.13. Calculate the productivity (i.e. D
P
) of a chemostat under the following conditions:
(1) Assume Monod kinetics apply. Assume that negligible amounts of biomass must
be converted to product (
determine YF
X/S
,
k
d
,
1%).
(2) Assume the Luedeking
e
Piret equation for product formation applies, i.e.
<
r
P
¼ ar
X
þ bX ¼ðam
G
þ bÞX
(3) Assume steady state:
S
0
¼
1.0 h
1
;
K
S
¼
1000 mg/L; D
¼
0.8
m
max
;
m
max
¼
10 mg/L; YF
X/S
¼
0.5 g-X/g-S;
0.5 h
1
mg-P/g-X
12.14. Consider a chemostat. You wish to know the
number
of cells in the reactor and the
fraction
of the cells that are viable (i.e. alive as determined by ability to divide).
(a) Write an equation for viable cell number (
n
v
). Assume that
m
net
¼
m
max
S
a ¼
0.4 mg-P/g-X;
b ¼
K
S
þ S
k
d
where
m
net
¼
net specific replication rate,
m
max
¼
maximum specific replication rate,
death rate.
K
S
is the saturation parameter.
(b) Derive an expression for the value of
S
at steady state.
(c) Write the number balance in the chemostat on dead cells (
n
d
).
(d) Derive an expression for the fraction of the total population which are dead cells.
12.15.
Escherichia coli
is cultivated in continuous culture under aerobic conditions with a
glucose limitation. When the system is operated at D
and
k
d
¼
0.2/h, determine the effluent
glucose and biomass concentrations by using the following equations (
S
0
¼
¼
5 g/L):
m
G
¼
m
max
S
0.25 h
1
,
K
S
¼
m
max
¼
(a) Monod equation:
, with
100 mg/L.
K
S
þ S
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