Civil Engineering - Waste Water Engineering - Discussion

19. 

When drainage to sewage ratio is 20, the peak dry weather flow is

[A]. 20% of the design discharge
[B]. slightly less than 5% of the design discharge
[C]. slightly more than 5% of the design discharge
[D]. none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Shreya said: (Apr 21, 2017)  
Anyone explain it please.

Souvik Kundu said: (Jan 15, 2018)  
Please explain it.

Rajeshkumar J said: (Feb 19, 2018)  
DWF = total supply of water * % of supply contributing to sewage, so when the ratio of drainage to sewage is high (20), then % of supply will be less, so DWF will be less than the design discharge.

Raj said: (Mar 1, 2018)  
Please explain it.

Er Mugundan R said: (Jul 1, 2018)  
Explain it, please.

Khushwant Rana said: (Nov 19, 2019)  
In dry weather only dry weather flow mean drainage flow will occur not the stormwater taken into account if drainage: sewage =1:20 then at dry flow only 1 unit will flow in a total of 21 unit mean % flow as compared to rainy season =1*100/21 = 4.76.

Hdhjdje said: (Dec 18, 2019)  
@Rana, Nice explanation.

Harsh Sharma said: (Dec 31, 2019)  
Qd/Qs = 20.

Qd = 20 Is ---- (1).

In rainy weather;

Q = Qd+ Qs.

from eq (1)-
Q = 21 Qs ----- (2).

In peak dry weather;

Q= Qd + Qs (here Qd = 0 since no storm water).
Hence,
Q= Is ----- (3).

From ek (2) & (3).

Dry weather condition/ Rainy weather condition = (Qs/ 21Qs)*100 = 4.76...

Therefore, the peak dry weather flow is slightly less than 5% of the design discharge.

Irfhan said: (Dec 6, 2020)  
Thanks @Harsh.

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