$3-3.(20$ points$)$ An industrial wastewater treatment plant uses a Plug$-$Flow Biological reactor for its

wastewater treatment. The following data are known: design flow $=5$ MGD$.$ The MLVSS is $75\%$ of the

MLSS$.$ The reaction rate constant is MLVSS$-$h$).$ The residence time is $5$ hours.

What will be the biomass concentration $($in MLSS$)$ and the recycle flow rate $(Q_R)$ needed to achieve

$90\%$ removal at the specified residence time if the Sludge Density Index is $9,000$ mg MLSS $/$ L$.$

$Q_r=2,031,250\frac{\text{g}\text{a}\text{l}}{\text{d}\text{a}\text{y}}(20$ points$)$ An industrial wastewater treatment plant uses a Plug$-$Flow Biological reactor for its wastewater treatment. The following data are known: design flow $=5$ MGD$.$ The MLVSS is $75\%$ of the MLSS$.$ The reaction rate constant is K $=0\mathrm{.}236$ L$/($g MLVSS$-$h$).$ The residence time is $5$ hours. What will be the biomass concentration $($in MLSS$)$ and the recycle flow rate $($QR$)$ needed to achieve $90\%$ removal at the specified residence time if the Sludge Density Index is $9,000$ mg MLSS $/$ L$.$