Civil Engineering - GATE Exam Questions - Discussion

Discussion Forum : GATE Exam Questions - Section 7 (Q.No. 3)
Use of coagulants such as alum
results in reduction of pH of the treated water.
results in increase of pH of the treated water.
results in no chnage in pH of the treated water.
may cause an increase in decrease of decrease of pH of the treated water.
Answer: Option
No answer description is available. Let's discuss.
6 comments Page 1 of 1.

Zub Baloch said:   1 year ago
@Md Shayan Sabri.

Alum is acidic in water and can reduce total alkalinity and pH by neutralizing carbonate and bicarbonate compounds with a greater decline in pH when applied to water with low initial total alkalinity. Its 1 doze reacts with 5.55 mg/l of alkalinity Expressed as CaCO3 and increases the CO2 content.

MD SHAYAN SABRI said:   2 years ago
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.

Kavery said:   3 years ago
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.

Surya said:   4 years ago
Alum reacts only when water has alkalinity.

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

Ibrahim said:   4 years ago
Alum is acidic in water. Thus the reduction in Ph.

Sheela said:   5 years ago
Please explain it.

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