The initial ultimate BOD after mixing of the James River is 32.5 mg/L. The DO in the river after the wastewater and river have mixed is at saturation. The river temperature is 10oC. At 10oC, the deoxygenation rate constant, k1 is 0.32 d-1 and the reaeration rate constant, k2 is 0.32 d-1. Determine the critical point tc and the critical DO.
The initial ultimate BOD after mixing of the James River is 32.5 mg/L. The DO in the river after the wastewater and river have mixed is at saturation. The river temperature is 10oC. At 10oC, the deoxygenation rate constant, k1 is 0.32 d-1 and the reaeration rate constant, k2 is 0.32 d-1. Determine the critical point tc and the critical DO.
The critical point(t) is determined by the equation:
Where is the deoxygenation rate constant at
L = ultimate BOD = 32.5 mg/L
= initial dissolved oxygen deficit
Oxygen deficit after time t () can be determined by the Streeter Phelps equation:
Where,
are the deoxygenation and re-oxygenation constant at .
Lets assume the initial dissolved oxygen is = 9.1 mg/L (at saturation)
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