A city of 50,000 people deposits 30.0 cfs (cubic ft per second) of sewage with a BOD of 101.0 mg/L and 1.9 mg/L of DO into a river that has a flow rate of 250 cfs and a flow speed of 1.75 tu Just upstream of (before) the release point the river has a BOD of 3.6 mg/L and a DO of 7.6 mg/L. The saturation value of DO is 8.5 mg/L. The de-oxygenation coefficient ka is 0.63/day and reaeration coefficient k, is 0.78/day. Assume complete mixing instantaneously. Show your calculations for partial credit. Part 1: Calculate the BOD immediately after mixing (assume steady state and perfect mixing conditions) Part 2: Calculate the DO immediately after mixing (assume steady state and perfect mixing conditions) Part 3: Calculate the initial deficit (Do) after mixing Part 4: Calculate the time in hours where there is a minimum DO concentration. Circle your answer from the choices below. Show your calculations for partial credit. A. 27.152 hr B. 30.094 hr C. 28.015 hr D. 21.074 hr

A city of 50,000 people deposits 30.0 cfs (cubic ft per second) of sewage with a BOD of 101.0 mg/L and 1.9 mg/L of DO into a river that has a flow rate of 250 cfs and a flow speed of 1.75 tu Just upstream of (before) the release point the river has a BOD of 3.6 mg/L and a DO of 7.6 mg/L. The saturation value of DO is 8.5 mg/L. The de-oxygenation coefficient ka is 0.63/day and reaeration coefficient k, is 0.78/day. Assume complete mixing instantaneously. Show your calculations for partial credit. Part 1: Calculate the BOD immediately after mixing (assume steady state and perfect mixing conditions) Part 2: Calculate the DO immediately after mixing (assume steady state and perfect mixing conditions) Part 3: Calculate the initial deficit (Do) after mixing Part 4: Calculate the time in hours where there is a minimum DO concentration. Circle your answer from the choices below. Show your calculations for partial credit. A. 27.152 hr B. 30.094 hr C. 28.015 hr D. 21.074 hr

Structural Analysis

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ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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Question

A city of 50,000 people deposits 30.0 cfs (cubic ft per second) of sewage with a BOD of 101.0 mg/L and 1.9 mg/L of DO into a river that has a flow rate of 250 cfs and a flow speed of 1.75 fu
Just upstream of (before) the release point the river has a BOD of 3.6 mg/L and a DO of 7.6 mg/L. The saturation value of DO is 8.5 mg/L. The de-oxygenation coefficient kd is 0.63/day and
reaeration coefficient kr is 0.78/day. Assume complete mixing instantaneously. Show your calculations for partial credit.
Part 1: Calculate the BOD immediately after mixing (assume steady state and perfect mixing conditions)
Part 2: Calculate the DO immediately after mixing (assume steady state and perfect mixing conditions)
Part 3: Calculate the initial deficit (Do) after mixing
Part 4: Calculate the time in hours where there is a minimum D0 concentration. Circle your answer from the choices below. Show your calculations for partial credit.
A. 27.152 hr
В. 30.094 hr
С. 28.015 hr
D. 21.074 hr

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