An activated sludge plug flow reactor $($PFR$)$ is designed to treat domestic wastewater for

organic matter removal only. The following design parameters are given:

$Y=0\mathrm{.}35\frac{mgMLVSS}{mgBO{D}_5},K_s=105$mgBO$\frac{D_5}{L},k_d=0\mathrm{.}10d^{-1},S_0=295$mgBO$\frac{D_5}{L},$

${}_m=0\mathrm{.}50d^{-1,}{}_c=8\mathrm{.}5$ days, $x=2800mgMLVS\frac{S}{L},Q_o=45000\frac{m^3}{d},xr=7150mg$

$MLVS\frac{S}{L},$

A$.$ What is the concentration of the soluble $BO{D}_5$ coming out of this PFR after

treatment?

B$.$ What is the volume of the PFR and what is the value of $Q_R?$

C$.$ What is the weight of sludge to be wasted daily $"$ Px $"$ in $K\frac{g}{d}?$

Hint: use this equation to calculate $"$Px$"$: $P_x=\frac{Vx}{{}_c}$

D$.$ What is the sludge wasting rate $(Q_w)$ in $\frac{m^3}{d}$ needed to have an effluent suspended

solids concentration $(x_e)$ of $30m\frac{g}{l}$ in the treated wastewater coming out of the final

sedimentation tank?