1. Online Lecture - 10
Self Purification of Streams and DO
Sag Curve
Problems
Wastewater Treatments
Module-II
1
2. • A wastewater treatment plant disposes of its effluent in a surface
stream. Characteristics of the stream and effluent are shown
below.
(a) What will be the dissolved oxygen conc. in the stream after 2
days? (b) What will be the lowest dissolved oxygen concentration as
a result of the waste discharge?
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13. Online Lecture - 11
Self Purification of Streams and DO
Sag Curve
Problems
Wastewater Treatments
Module-II
13
14. Using the following data, find out DO at the end of 1 and 2 days, also find Critical DO.
Take deoxygenation constant as 0.1/day, reoxygenation constant as 0.3/day
and saturation DO as 9.1mg/l
River Wastewater
Flow (m3
/s) 25 2
DO (mg/l) 9.1 0
5-day BOD (mg/l) 2 200
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19. Assignment 4
• Q1. Write Streeter Phelps equation and explain meaning of each
and every term in it
• Q2. Using the following data, find out DO at the end of 2 and 4 days, also find Critical
DO.
Take deoxygenation constant as 0.1/day, reoxygenation constant as 0.3/day
and saturation DO as 9.1mg/l
River Wastewater
Flow (m3
/s) 25 3
DO (mg/l) 9.17 1
5-day BOD (mg/l) 0 250
