Estimate the required air flow rate for the new activated sludge plant at Perryville (Pr...

Estimate the required air flow rate for the new activated sludge plant at Perryville (Problems 16-1 , 16-6 , 16-9 , and 16-12 ). Use the following assumptions in preparing the estimate:

Problems 16-12

Estimate the mass of oxygen to be supplied (kg/d) for the new activated sludge plant at Perryville ( Problems 16-1 , 16-6 , and 16-9 ). Assume that BOD₅ = rbsCOD and that it is 68% of the bCOD.

Problems 16-9

Estimate the mass of sludge to be wasted each day from the new activated sludge plant at Perryville ( Problems 16-1 and 16-6 ).

Problems 16-6

Determine the return sludge concentration ( X '_r ) that results in the maximum return sludge flow rate for Perryville’s proposed activated sludge plant described in Problem 16-1 . Also estimate the mass flow rate of sludge wasting. Use the following assumption:

MLVSS fraction of MLSS = 0.70

Problem 16-1

Using the assumptions given in Example 16-1 , the rule-of-thumb values for growth constants in the example, and the further assumption that the influent BOD₅ was reduced by 32% in the primary tank, estimate the liquid volume of a completely mixed activated sludge aeration tank for Perryville. The design flow rate is 34,560 m³/d and the design influent BOD₅ is 188 mg/L. Assume an MLVSS of 2,000 mg/L.

Example 16-1

The town of Lawrence has been directed to upgrade its primary WWTP to a secondary plant that can meet an effluent standard of 30.0 mg/L BOD₅ and 30.0 mg/L total suspended solids (TSS). They have selected a completely mixed activated sludge system. Assuming that the BOD₅ of the TSS may be estimated as equal to 63% of the TSS concentration, estimate the required volume of the aeration tank. The following data are available from the existing primary plant.