Civil Engineering - Waste Water Engineering - Discussion


For sewer mains of 0.5 to 1 m diameter, the ratio of maximum daily sewage flow to the average daily sewage flow is assumed

[A]. 1.5
[B]. 2.0
[C]. 2.5
[D]. 3.0

Answer: Option B


No answer description available for this question.

Raajeev Yadav said: (Jul 19, 2015)  
If diameter is more then sewage flow is also more.

So V/v=D/d=1/0.5=2.

Har said: (Aug 18, 2017)  
(a)maximum to the average flow of sewage is between 1.5 to 1.0 and average to the minimum is between 1.2 to 1.0.

(b)For estimating design discharge following relation can be considered: Maximum daily flow = Two times the annual average daily flow (representing seasonal variations) Maximum hourly flow = 1.5 times the maximum daily flow (accounting hourly variations) = Three times the annual average daily flow As the tributary area increases, peak hourly flow will decrease. For smaller population served (less than 50000) the peak factor can be 2.5, and as the population served increases its value reduces. For large cities, it can be considered about 1.5 to 2.0. Therefore, for outfall sewer the Page 6.

The peak flow can be considered as 1.5 times the annual average daily flow. Even for a design of the treatment facility, the peak factor is considered as 1.5 times the annual average daily flow. The minimum flow passing through sewers is also important to develop self-cleansing velocity to avoid silting in sewers. This flow will generate in the sewers during late night hours. The effect of this flow is more pronounced on lateral sewers than the main sewers. Sewers must be checked for minimum velocity as follows: Minimum daily flow = 2/3 Annual average daily flow Minimum hourly flow = 1/2 minimum daily flow = 1/3 Annual average daily flow.

(c) THE QUESTION IS SIMPLE THE MAXIMUM DAILY sewage flow to the average daily sewage flow=2, BECAUSE AT TIME OF NO USE(NOON, NIGHT) IT MINIMUM AS ZERO(0) & MAXIMUM IS 2, SO THAT average daily sewage flow=(0+2)/2=1 & MAXIMUM DAILY sewage flow=2, SO THAT RATIO=2/1=2.

Prince said: (Aug 6, 2021)  
Small sewers/ lateral 0.25 m in diameter: 4.0.
Branch sewers 0.5 m in diameter: 3.0.
Main sewers 0.5 to 1m diameter : 2.0.
Trunk sewers 1.25 m diameter and above : 1.5.

Shana said: (Aug 13, 2021)  
The average annual daily sewage flow of a city is 60 MLD. The maximum hourly flow of the city, assuming daily and hourly peak factors as 2 and 1.5, respectively.

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