Question $2$

An engineer is deciding between using a PFR or a CSTR for the oxidation of $F{e}^{2+}$ using oxygen.

The first order oxidation has a rate constant of $0\mathrm{.}168mi{n}^{-1}.$ The initial concentration of soluble

iron is $2m\frac{g}{L}($assume excess $O_2)$ and the aesthetic objective is $0\mathrm{.}3m\frac{g}{L}.($a$)$ What is the

residence time required to accomplish sufficient removal $($for both reactors$)?($b$)$ If the plant flow

rate is $100,000\frac{L}{d},$ what should the volume be for a PFR or a CSTR$?$