where $E_{}=$BOD renoval efficiency at temperature $T$ in $C,$ percent

$E_{20}=$BOD remoral efficiency at $20C,$ percent

EXAMPLE $9-3$ Trickling filter Sizing Using NRC Equations A municipal wastewater having a

BOD of $250\frac{g}{m^3}$ is to be treated by a two$-$slage trickling filtcr. The desired effluent

quality is $25\frac{g}{m^3}$ of BOD. If both of the filter depths are to be $1\mathrm{.}83m$ and the recircu$-$

lation ratio is $2$:$1,$ find the required filter diameters. Assume the following design

assumptions apply. $($Note: $\frac{g}{m^3}=m\frac{g}{L}.)$

$914$ Chapter $9$ Attached Growth and Combined Biological Treahment Processes