In the preliminary analysis of alternatives for stabilizing a mixture of primary and WAS sludge from Knight Falls' activated sludge plant, your boss has asked you to design an aerobic digester. The...

In the preliminary analysis of alternatives for stabilizing a mixture of primary and WAS sludge from Knight Falls' activated sludge plant, your boss has asked you to design an aerobic digester. The sludge flow rate is 404 m /d. The solids concentration 2.8% and the specific gravity of the sludge is 1.01. Use the following data for the design:

Winter conditions govern

Temperature of digester contents = 15°C

VSS = 0.7 TSS

VSS reduction goal = 40%

Influent BOD = 1,700 mg/L

Fraction of influent BOD consisting of primary solids = 0.28

Sludge concentration is 70% of the incoming thickened sludge concentration

Diffused air mixing is to be used