You are asked to design two secondary rectangular clarifiers following a conventional activated sludge system $.$ The average flowrate to the activated sludge system is $15142$ m$/$d $(4$ mgd$)$ with a $50\%$ RAS return flow. The MLSS in the activated sludge system is $2500$ mg$/$L$.$

a$.$ Select a surface overflow rate and determine the required area for the clarifiers based on clarification.

b$.$ Select an appropriate solids loading rate and determine the area required for thickening.

C$.$ Using the results from the previous parts, determine the length and width for each darifier using a length$-$to$-$width ratio of $8$:$1.$

d$.$ Choose and justify a depth and calculate the HRT for the clarifier. The HRT should be between $2$

solids concentration of

and $4$ hours.

e$.$ Design a weir system so that the weir loading rate is at or below standard values. Assume a peak

factor of $2\mathrm{.}0$