Question $2$

In a certain chemical treatment process, a mixed flow reactor and plug flow

reactor is used in sequence. The flow rate entering the mixed flow reactor and

plug flow reactor is $9\frac{m^3}{s}$ and the pollutant enters the mixed flow reactor in

a separate inlet stream with a flow rate of $2\frac{m^3}{s}$ and a pollutant concentration

of $50m\frac{g}{L}.$

$($i$)$ What could be the advantage of such a setup?

$($ii$)$ Determine the pollutant concentration entering the plug flow

reactor assuming that the chemical treatment occurs in this reactor.

$($iii$)$ If the plug flow reactor has a cross sectional area of $0\mathrm{.}5m^2$ and is

$50m$ long, evaluate the pollutant concentration exiting the reactor.

$($Assume that the pollutant is removed with a first order decay $(-$

$k(V)$ rate constant, $k,$ of $\frac{0\mathrm{.}20}{s}).$