Civil Engineering - GATE Exam Questions - Discussion


Use of coagulants such as alum

[A]. results in reduction of pH of the treated water.
[B]. results in increase of pH of the treated water.
[C]. results in no chnage in pH of the treated water.
[D]. may cause an increase in decrease of decrease of pH of the treated water.

Answer: Option A


No answer description available for this question.

Sheela said: (Sep 17, 2018)  
Please explain it.

Ibrahim said: (Jan 11, 2019)  
Alum is acidic in water. Thus the reduction in Ph.

Surya said: (Feb 22, 2019)  
Alum reacts only when water has alkalinity.

By adding alum, alkalinity of water is reduced and infact alkalinity reduces, ph reduces.

Kavery said: (Nov 11, 2019)  
Alum works when water is alkaline(6.5 - 8.5)pH.

When alum added to water, then pH decrease i.e., the alkalinity of water increase.

Md Shayan Sabri said: (Oct 11, 2020)  
Alum does not work in acidic medium by increasing pH value we add caco3 to increase ph. So we can say if we use alum in water it reduces ph value of water.

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