Chapter 7 fe exam formatted problems 7 If the bod

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 lb_m/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?