$(10)$ Assume that a primary sedimentation unit removes $60\%$ of the suspended solids and $40\%$ of the $BO{D}_5$ of the raw sewage from a flow rate of $4,000\frac{m^3}{?}$ day containing an average of $230m\frac{g}{L}BO{D}_5$ and $260m\frac{g}{L}$ of suspended solids.

a$.$ Draw and label a sketch of this system, and determine the $SS$ and $BO{D}_5$ concentrations in the primary sedimentation effluent flow.

b$.$ Also determine the mass of primary sludge produced per day at average flow conditions, as dry solids.