The Wilson Wastewater Treatment Plant currently provides primary treatment for a flow rate of 2500 m3/day....

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

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

(4 pts) Estimate the sludge age (q_c) to achieve the target effluent criteri
(6 pts) Estimate the hydraulic retention time and volume of the aeration tank (in m³).
(4 pts) Compute the F/M ratio.
(4 pts) Estimate the observed yield in the system (mg VSS/mg BOD₅ removed)
(4 pts) Calculate the net waste activated sludge produced (kg VSS/day).
(4 pts) Calculate the cell solids (VSS) in the effluent in mg/L based on the designed suspended solids target for the effluent.
(4 pts) Calculate the cell solids (VSS) in the settled sludge in mg/L based on the designed SS concentration in the secondary settler.
(4 pts) Determine the sludge waste flow rate (m³/day) using sludge age. Do not ignore biomass in the effluent.
(4 pts) Determine the sludge return flow rate (m³/day). Do not ignore biomass in the effluent.

Expert Solution

Ally Wells answered 8 months ago

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