$($c$)$ A $5800m^3$ aeration tank is used in a step$-$aeration activated sludge secondary

wastewater treatment. The influent wastewater flow is $24500m^3$ per day and the

mixed liquor suspended solids $($MLSS$)$ concentration is $2200mg{L}^{-1}.$ If the

average influent biological oxygen demand $($BOD$)$ is $124mg{L}^{-1},$ determine the

food$-$to$-$microorganism $($F$/$M$)$ ratio.

$[3$ MARKS$]$