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Unformatted text preview: DO and Streeter Phelps ¡ Lecture#47 ¡ Introduction to Oxygen Sag Curve ¡ Streeter Phelp’s Equation ¡ ICP#39 ¡ Reading V: Ch. 7 (pg. 145-153); Streeter Phelps Equation Handout (Resource Folder) What you should know ¡ 1. What is an oxygen deficit (D)? ¡ 2. What impact does biodegradation have on dissolved oxygen concentration (DO) and D? ¡ 3. What impact does re-aeration have on dissolved oxygen concentration (DO) and D? ¡ 4. What is the oxygen sag curve and how to we estimate the critical deficit (D c ) and critical distance (x c ) downstream from a discharge? Oxygen Deficit and Streeter-Phelps ¡ question: What happens to oxygen in a river when wastewater with high organic content is discharged into a river? ¡ answer: It produces an oxygen deficit ¡ Streeter-Phelps equation allows a prediction of impact of waste on river oxygen as a function of distance from discharge Oxygen Deficit and Streeter-Phelps D = DO sat- DO t Biodegradation of organics removes oxygen and increases deficit Reaeration generates oxygen and reduced deficit ν Streeter-Phelps and Oxygen Sag Curve Wastewater discharge point: assume to be instantaneously and well-mixed across river Oxygen Deficit and Streeter-Phelps ¡ D = DO sat – DO t (DO ≡ dissolved oxygen) ¡ Do mass flow balance on D (deficit) ¡ rate of mass in – rate of mass out + rate of generation – rate of decay = rate of mass accumulation ¡ rate of “generation” of deficit = biodegradation (deoxygenation generates deficit) ¡ rate of “decay” of deficit = reaeration (reoxygenation reduces deficit) Oxygen Deficit and Streeter-Phelps Deficit, D (increases deficit) (decreases deficit) Oxygen Reaeration Constants ¡ k T = k 20 θ T-20 ° (k value increases with temperature; θ∼ 1.024) ¡ k r = 3.9= 3....
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This note was uploaded on 04/17/2008 for the course CEE 260 taught by Professor Kimf.hayes during the Fall '06 term at University of Michigan.
- Fall '06