Exam Study Guide: Hardness Removal

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When faced with a licensing exam, don't struggle with test anxiety! Use the question below and others from our Exam Study Guide series to study and prepare for exam questions. Take a look at this sample water treatment licensing question along with an explanation of the correct answer.

Sample question:

What method of hardness removal is capable of producing zero hardness?

A) Ion exchange
B) Lime – soda ash
C) Sequestration
D) Chelation

Answer: Ion exchange softening is capable of producing a water of zero hardness. Zero hardness is usually not recommended because the water then becomes corrosive. To avoid zero hardness, a public water supply should blend softened water from the ion exchange softener with treated water that bypasses the ion exchange process.

So, the correct answer is A.

Reference: Water Treatment Plant Operation. 5th Edition, Volume ll, California State University, Sacramento. Page 78

About the author
Drew Hoelscher is program director of drinking water operations at the Environmental Resources Training Center (ERTC) in Edwardsville, Illinois.


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