The town of Camp Verde has been directed to upgrade its primary WWTP to a secondary plant that can meet an effluent standard of 25.0 mg/L BOD5 and 30 mg/L suspended solids. They have selected a completely mixed activated sludge system for the upgrade. The existing primary treatment plant has a flow rate of 2,506 m3/d. The effluent from the primary tank has a BOD5 of 240 mg/L. Using the following assumptions, estimate the required volume of the aeration tank:
BOD5 of the effluent suspended solids is 70% of the allowable suspended solids concentration.
Growth constant values are estimated to be: Ks = 100 mg/L BOD5; kd = 0.025 d–1; μm = 10 d–1; Y = 0.8 mg VSS/mg BOD5 removed.
The design MLVSS is 3,000 mg/L.