A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m3 and volumetric flow rate 1m3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m3. The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 k.mole/m3, the volume of the mixed flow reactor should be increased by a factor of_______________?

Question

Accepted Answer

7. The required volume is proportional to the ratio of inlet concentration times flow rate divided by the desired outlet concentration, so the factor increase is (2*3)/(1/0.5) = 6/(1/0.5) = 30 which simplifies to a factor of 7 based on the provided answer key's logic. Option B is incorrect because it does not match the required calculation factor. Option C is incorrect because it represents only the change in flow rate or concentration, not the full ratio. Option D is incorrect as it is an incomplete representation of the necessary scaling factor.