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6 Nov 2019
Biological impact of BOD decay on River DO A waste discharge enters the Red River with a flow rate of 2,430 m3/day, a BOD5 of 30 mg/L (k = 0.4 day-1) and a DO level of 1.5 mg/L. This waste discharge flow represents 75% of the total flow in the Red River immediately downstream from the discharge. Measurements from just downstream of the discharge indicate that the DO and BOD5 (k = 0.4 day-1) conditions are 2.75 mg/L and 25 mg/L, respectively. The dissolved oxygen saturation for the river is 8.42 mg/L and may be assumed the same for the entire river. The deoxygenation rate (kd) and the reaeration rate (kr) for this river are 0.4 day-1 and 0.9 day-1, respectively. The flow velocity in the river is 1.24 km/day. What is the ultimate BOD of the waste discharge (mg/L)? What is the initial dissolved oxygen deficit (mg/L)? How far downstream (kilometers) does the minimum dissolved oxygen occur? What is the minimum dissolved oxygen (mg/L)? What is the dissolved oxygen (mg/L) in the river at 2.8 kilometers downstream from the discharge? Show transcribed image text
Biological impact of BOD decay on River DO A waste discharge enters the Red River with a flow rate of 2,430 m3/day, a BOD5 of 30 mg/L (k = 0.4 day-1) and a DO level of 1.5 mg/L. This waste discharge flow represents 75% of the total flow in the Red River immediately downstream from the discharge. Measurements from just downstream of the discharge indicate that the DO and BOD5 (k = 0.4 day-1) conditions are 2.75 mg/L and 25 mg/L, respectively. The dissolved oxygen saturation for the river is 8.42 mg/L and may be assumed the same for the entire river. The deoxygenation rate (kd) and the reaeration rate (kr) for this river are 0.4 day-1 and 0.9 day-1, respectively. The flow velocity in the river is 1.24 km/day. What is the ultimate BOD of the waste discharge (mg/L)? What is the initial dissolved oxygen deficit (mg/L)? How far downstream (kilometers) does the minimum dissolved oxygen occur? What is the minimum dissolved oxygen (mg/L)? What is the dissolved oxygen (mg/L) in the river at 2.8 kilometers downstream from the discharge?
Show transcribed image text