|Chapter 7 FE EXAM FORMATTED PROBLEMS
7-1. If the BOD5 and ultimate BOD of a municipal wastewater are 200 mg/L and 457 mg/L respectively, what is the reaction rate constant?
From Eq. 7-4
7-2. Twenty six million gallons per day of wastewater with a DO of 1.00 mg/L is discharged into a river with a DO of 6.00 mg/L. If the flowrate of the river is 165 x 106 gal/d and saturation value of dissolved oxygen is 9.17 mg/L, what is the oxygen deficit after compete mixing of the two flows?
From Eq. 7-25
7-3. What is the mass loading (in lbm/d) of a 33 MGD wastewater discharge with an ultimate BOD of 30.0 mg/L?
7-4. A stream survey revealed that the reaeration constant is 0.05 d-1 and the deoxygenation constant is 0.03 d-1. If the initial deficit is 5.00 mg/L and the ultimate BOD after mixing is 12.0 mg/L, how long will it take to reach the critical point in the DO sag?
From Eq. 7-46