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346 4. Adsorption and Ion Exchange

while the degree of utilization of the bed is (eq. (4.202))

q
br 0.351
q o

or 35.1%. These relationships provide us with the ability to plot the utilization (%) v ersus
Q rel (BV/h) (Figure 4.39).
Low utilization means that at the breakpoint, i.e. when the operation of the bed is
stopped, the portion of the solid material in the bed used during the service time is lo , w
generated,
which is undesirable. Especially if the material cannot be re low utilization
,
means that the unused material is lost.
Finally, as has been noted, although the e the mean concen- xit concentration is 10 ppm,
wer
tration of the collected waste is considerably loThe total mass of the solute passed
.
through the bed is V br C , where V br is the exit solution volume until the breakpoint. F or
o
e flo v operation under a relatiw rate of 5 BV/h (eq. (4.200)):
M out V C br o q V 4598 mg
br o b
Then, the mean exit concentration is (eq. (4.201))
M out
C r avr,b 0.03 ppm
V
br
The mean e xit concentration C avr,br xit concen- is alays much lower than the breakpoint e w
xample, tration; in our e it is almost 0.3% of the breakpoint concentration.

100

80

60

(%)
η
40
20

0
0 1 2 3 4 5 6 7
Q rel (BV/h)
Figure 4.39 Utilization (%) v ersus Q rel (BV/h).