A municipal wastewater treatment plant discharges 20,000 m3/d of treated wastewater to a stream. The wastewater...

A municipal wastewater treatment plant discharges 20,000 m3/d of treated wastewater to a stream. The wastewater has a BOD5 of 30 mg/L with a k1 of 0.23 d-1. The temperature of the wastewater is 20 oC, and the dissolved oxygen is 2.0 mg/L. The stream just above the point of wastewater discharge flows at 0.65 m3/s, has a BOD5 of 5.0 mg/L, and is 90% saturated with oxygen. The temperature of the stream is also 20 oC. After mixing, the combined stream and wastewater flows at a velocity of 0.5 m/s and the reaeration constant, k2, is 0.45 d-1. (a) What is the oxygen level of the stream when it reaches a point 2 days downstream? (b) What is the critical oxygen level in the stream and how far downstream will it occur?

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Ally Wells answered 1 year ago

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