The Wilson Wastewater Treatment Plant currently provides primarytreatment for a flow rate of 2500 m³/day. The effluentfrom the primary tank has a soluble BOD₅= 240 mg/L. Youneed to design an activated sludge treatment to update the plant.The secondary effluent standards to meet are 25.0 mg/LBOD₅ total (suspended and soluble BOD) and 30 mg/Lsuspended solids. Use the following assumptions:

• Target soluble BOD₅ in the effluent of the secondarytreatment is 2.5 mg/L.
• Growth constants can be estimated as K_s=145 mg/LBOD₅; k_d=0.025 d^-1;m_m=8 d^-1; Y=0.8 mg VSS/mg BOD₅removed.
• The designed MLVSS is 3,000 mg/L.
• The settler is designed to achieve 12,000 mg SS/L in thesettled sludge.
• The MLVSS fraction of MLSS is expected to be 0.7

1. (4 pts) Estimate the sludge age (q_c) to achieve thetarget effluent criteri
2. (6 pts) Estimate the hydraulic retention time and volume of theaeration tank (in m³).
3. (4 pts) Compute the F/M ratio.
4. (4 pts) Estimate the observed yield in the system (mg VSS/mgBOD₅ removed)
5. (4 pts) Calculate the net waste activated sludge produced (kgVSS/day).
6. (4 pts) Calculate the cell solids (VSS) in the effluent in mg/Lbased on the designed suspended solids target for theeffluent.
7. (4 pts) Calculate the cell solids (VSS) in the settled sludgein mg/L based on the designed SS concentration in the secondarysettler.
8. (4 pts) Determine the sludge waste flow rate(m³/day) using sludge age. Do not ignore biomass in theeffluent.
9. (4 pts) Determine the sludge return flow rate(m³/day). Do not ignore biomass in the effluent.