Engineering Board Exam Reviewer · Environmental Engineering · hard
A river (5 m3/s, DO = 7.5 mg/L) receives wastewater (0.5 m3/s, DO = 1.0 mg/L). The saturation DO is 8.2 mg/L. What is the initial oxygen deficit after mixing?
- 6.91 mg/L
- 0.70 mg/L
- 3.95 mg/L
- 1.29 mg/L
Answer
D. 1.29 mg/L
Solution
Mixed DO = (5 × 7.5 + 0.5 × 1.0)/5.5 = 6.91 mg/L. Deficit D0 = DOsat - DO = 8.2 - 6.91 = 1.29 mg/L.
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