DABTU Wastewater Treatment T E (CIVIL)

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?

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

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

20. • Q3.

21. Q4.

22. Assignment 4
Q5.
22
River Sewage
Flow (m3/sec) 8 1.25
BOD5 2 250
DO 8 0
Temp 0C 15 20
Determine Properties of mix for above parameters