Question $2.(50$ points$)$

An industrial waste is to be treated with a trickling filter $($TF$)$ followed by an activated sludge $($AS$)$

process. The wastewater flowrate is $20,000\frac{m^3}{d}$ and is equalized. Primary settling is not used

because the wastewater contains mainly soluble organic substances without suspended solids. The

trickling filter $($depth$,D=6\mathrm{.}1m)$ contains conventional plastic packing with a specific surface

area of $100\frac{m^2}{m^3}$ and the operational SRT for the activated sludge process is to be $15d$ at $5C$

during winter. Ignore denitrification in the TF$/$AS process and recycling from the secondary

clarifier. $**SRT=HRT($i$.$e$.,$ no internal recycling$).$

The characteristics of the industrial waste, data derived from pilot plant studies, and related

design data are presented below. Using these data, determine concentration of VSS $(\frac{g}{m^3})$ of $(1)$

the TF and $(2)$ the AS processes to be maintained during winter operation $(5C).$ For a short

SRT value, cell debris from the TF to the AS process is negligible.

$*$Trickling filter process:

SRT $=1d$

Influent BOD $=1200m\frac{g}{L}$ and effluent BOD $=284m\frac{g}{L}$

Solids synthesis yield, $Y_H=0\mathrm{.}6g$ VSS$/$g BOD removal

k at $20C=0\mathrm{.}175\frac{(\frac{L}{s}{)}^{0\mathrm{.}5}}{m^2}$

Temperature correction value for $k,=1\mathrm{.}06$

Endogenous decay, $b_H=0\mathrm{.}12gVS\frac{S}{g}$ VSS $\frac{?}{d}$ at $20C$

$=1\mathrm{.}035$ for $b_H$

Trickling filter hydraulic application rate, $q=0\mathrm{.}015\frac{m^3}{m^2}\frac{?}{\text{m}\text{i}\text{n}}$

Activated sludge process:

Solids synthesis yield, $Y_H=0\mathrm{.}6g$ VSS $\frac{?}{g}$ BOD removal

Endogenous decay, $b_H=0\mathrm{.}12gVS\frac{S}{g}$ VSS $\frac{?}{d}$ at $20C$

$k=6\mathrm{.}0$gBO$\frac{D}{g}VS\frac{S}{d}$ at $20C$

$Ks=90$mgBO$\frac{D}{L}$

$=1\mathrm{.}035$ for $b_H$ and $k$