PS7_Sp10 - first-order decay model for biochemical oxygen...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
CEE 320 Assignment #7 Environmental Engineering Complete before Wednesday 17 March Lake Q r + Q w Q r Q w O 2 PROBLEMS: 1. Textbook Chapter 5 Review Question 14 (page 216) 2. Textbook Chapter 5 Review Question 17 (page 216) 3. Textbook Chapter 5 Review Question 23 (page 216) 4. Textbook Chapter 5 Problem 5-18 (page 218) 5. Analyzing the effects of sewage discharge to a lake A small city (population 10,000) discharges its untreated sewage into a nearby shallow freshwater lake. A river flows into the lake and another flows out such that the water volume remains constant. The winds are strong enough to keep the lake water well mixed. Determine the dissolved oxygen content of the lake under steady-state conditions (mg L -1 ). Represent the lake as a CMFR. Use the
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: first-order decay model for biochemical oxygen demand (BOD) and the model we derived in class for oxygen transfer from the atmosphere. Ignore any effect of aquatic life on the dissolved oxygen balance. DATA: Lake: Volume: V = 2 x 10 7 m 3 Average depth: d = 10 m Temperature: T = 20 o C River (incoming): Flow rate: Q r = 0.5 m 3 s-1 Dissolved oxygen: DO r = 9.0 mg L-1 Oxygen transfer from the atmosphere to the lake: Transfer coefficient: K = 5 x 10-5 cm s-1 Saturation concentration, dissolved oxygen: DO sat = 9.1 mg L-1 Waste: Flow rate: Q w = 0.075 m 3 s-1 BOD content: BOD w = 150 mg L-1 BOD decay rate: k = 0.2 d-1 Dissolved oxygen: DO w = 8 mg L-1 READING: Chapter 9, pp. 332-374 Interfacial mass transfer example posted on website...
View Full Document

Ask a homework question - tutors are online