A step feed biological nitrogen removal process divided into four equal passes with equal

volume used for anoxic and aerobic zones. The flow splits to each pass are $0\mathrm{.}1,0\mathrm{.}4,0\mathrm{.}3$ and $0\mathrm{.}2$ of the influent flow, for passes $1$ through $4$ respectively. Total tank volume is $9870$ m$3,$ and anoxic tank volume is $20\%$ of aerobic tank volume. $($Assume ww characteristics and all other design conditions similar to Q$2($Q$2$has been attached for your reference$)$

$($a$)$ determine aerobic and anoxic tank in each pass

$($b$)$ Determine the RAS concentration $($Xr$)$

$($c$)$ Determine the MLSS in each pass