$[20$ points$]$ E$-$B Problem $3\mathrm{.}23$

You wish to design a biological treatment system for iron contained in drainage water from mine tailings.

The water contains no particulate material. You wish to consider aerobic oxidation of the soluble $Fe(II)$

contained in the wastewater to $Fe(III),$ which you will then precipitate in a subsequent reactor by adjustment

of $pH.$ For Fe$($II$)$ oxidation, $[{}_x^{\text{m}\text{i}\text{n}}{]}_{lim}=2\mathrm{.}2d,f_s^0-0\mathrm{.}072,$ and $b=\frac{0\mathrm{.}1}{d}.$

a$)$ Estimate the detention time for a CSFTR reactor with an $SF$ of $10,$ and $x_v$ of $1,000m\frac{g}{l}.$

b$)$ Estimate the efficiency of $Fe(II)$ oxidation if $S^0=10m\frac{g}{l}$ and $K=10m\frac{g}{l}.$

c$)$ Write a stoichiometric equation for the reaction occurring.

d$)$ Estimate the grams of oxygen required per gram $Fe(II)$ oxidized. The molecular weight of $Fe$ is $55\mathrm{.}8.$

e$)$ Estimate the grams of ammonia$-$N per gram $Fe(II)$ oxidized that should be added to satisfy bacterial

needs.