Engineering Board Exam Reviewer · Environmental Engineering · hard
A well-mixed lake (volume 100,000 m3, outflow 10,000 m3/day) receives 1000 kg/day of a pollutant that decays with k = 0.1/ day. What is the steady-state concentration in the lake?
- 50 mg/L
- 100 mg/L
- 9.1 mg/L
- 10 mg/L
Answer
A. 50 mg/L
Solution
At steady state: C = W/(Q + kV) = (1,000,000 g/d)/(10,000 + 0.1 × 100,000) m3/d = 50 g/m3 = 50 mg/L.
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