Civil Engineering - Waste Water Engineering - Discussion


The coagulant widely used for sewage treatment, is

[A]. alum
[B]. ferric chloride
[C]. ferric sulphate
[D]. chlorinated copperas.

Answer: Option B


No answer description available for this question.

Shilpa said: (Jun 29, 2016)  
Why ferric chloride is used?

Ritwsh said: (Oct 20, 2016)  
The answer should be alum. Alum is widely used.

Souvik said: (Oct 20, 2016)  
The correct answer is A. alum.

Vasu Namdev said: (Nov 15, 2016)  
Alum is widely used for drinking water and ferric chloride is widely use for sewage.

Sreejith Tk said: (Dec 1, 2016)  
Alum is the right answer.

Adhi said: (Dec 23, 2016)  
Alum is used in the treatment of drinking water NT in sewage treatment.

Shawshank said: (Feb 27, 2017)  
Though ferric salts work over a wide range of pH and are cheaper than alum but still alum should be the right answer because ferric salts attract iron bacteria and lead to incrustation in sewer pipes.

Manoj Kumar said: (Mar 24, 2017)  
I think the answer is A.

Sagar said: (Mar 25, 2017)  
Alum is used in drinking water not in sewage treatment plant.

Debasish said: (Jun 29, 2017)  
I think the correct answer is A.

Satyam Shukla said: (Jul 12, 2017)  
Feric chloride is correct answer, alum is widely used in drinking water as a coagulant.

Msr said: (Sep 27, 2017)  
Alum is widely used.

Reference SK Garg Environmental book vol II.

Tapash said: (Feb 10, 2018)  
Alum is not widely used as it form spongy floc which settle slowly. BOD removal 80 to 90 % where as alum has 60%. Feric chloride is right answer.

Sandeep said: (Feb 18, 2018)  
Good explanation @Vasu Namdev.

Mona said: (Mar 24, 2018)  
Ferric chloride is the coagulant of choice for many industrial and sanitary wastewater treatment applications, due to its high efficiency, effectiveness in clarification, and utility as a sludge dewatering agent. The chemical leaves slight residual color, and offers very good turbidity removal.

Vbyu said: (Apr 11, 2018)  
Alum in drinking water.

Rajkumar said: (May 2, 2018)  
Alum used drinking water.
Ferric chloride is for Sewage treatment.

Ningu said: (Jul 17, 2018)  
B is the correct Answer for sewage treatment. For water treatment Alum is used.

Narendra said: (Aug 18, 2018)  
Yes, alum is used for drinking water. By here it is for sewage treatment. Then ferric salts are used.

Achiba said: (Oct 23, 2018)  
Alum (aluminium) sulphate is coagulant.

Vishal said: (Feb 19, 2019)  
Ferric chloride is the right answer.

Alum is widely used for water treatment for supply however it is not that much efficient as ferric chloride but ferric chloride cause corrosion problem in supply pipes that's why it is not prefered for water supply.

In sewage treatment, the pipes are RCC pipes hence no problem of corrosion arise and it is preferred for sewage treatment.

Dhananjay said: (Feb 22, 2019)  
Thanks @Vishal.

Masoom said: (Mar 12, 2019)  
Alum only for drinking water not to sewage, in sewage we should use chlorinated compound so fecl2 is the best coagulant.

Ashutosh said: (Apr 17, 2019)  
Both B & C are correct. Ferric Alum is generally used for treating Sewage whereas Alum is used for treating water.

Mithunkumar said: (May 27, 2019)  
Thanks @Vishal.

Vasu Namdev said: (May 27, 2020)  
Thank you @Sandeep.

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