$($a$)$ Population equivalent is a measurement to estimate the amount of

wastewater entering a sewage treatment plant. Explain why population

equivalent is employed as a mode of estimation.

$($b$)$ Total suspended solid is one of the important parameters in the

characterization of any wastewater. Using diagram$/$equation$,$ show the

correlation of different types of solid. Then, state briefly the procedures

to determine the two commonly measured solids.

$(6$ marks$)$

$($c$)$ Daily, an average of $22,500m^3$ of domestic sewage enters a primary

clarifier. The maximum overflow rate during peak flow is $45\frac{m^3}{m^2}.$day.

Compute the area of the clarifier when $Q_{\text{p}\text{e}\text{a}\text{k}}=1\mathrm{.}5Q_{\text{a}\text{v}\text{e}\text{r}\text{a}\text{g}\text{e}\text{.}\text{T}\text{h}\text{e}\text{n}\text{,}\text{f}\text{i}\text{n}\text{d}\text{t}\text{h}\text{e}}$

HRT$,$ dimension and weir loading of the clarifier during both design and

peak flow. Does the weir loading fall within the minimum and maximum

value? Assume that the depth of the clarifier is $6$ m $.$