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A CMFR is operating at steady state with a second order decay reaction of rate constant k2=0.5 L/mg/d. It is exactly meeting its goal of 99.9% removal efficiency and the allowed maximum effluent concentration of 0.05 mg/L. The volumetric flow rate is 450 m3Id.
a. What is the influent concentration in mg/L?
b. What is the reactor volume in m3? What volume would be required if the removal efficiency goal were 99.0%? c(5). If the CMFR is replaced with a PFR, what reactor volume is needed (in m3)?
a) conversion = 99.9%
X = 0.999
C = 0.05 mg/L
Influent concentration C0 = 50 mg/L
For CSTR, performance equation is given by
v0 = 450 m3/d = 450000 L/d
For 2nd order reaction,
-r = kC2
C = C0(1-X)
For X = 0.999
.: V = 1.7982 x 1010 L = 1.7982 x 107 m3
For X = 0.99
.: V = 178200000 L = 178200 m3
For PFR, performance equation is given by
On integrating we get
For X = 0.999
.: V = 1.7982 x 107 L = 1.7982 x 104 m3